Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco Americas Headquarters

Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco Americas Headquarters
Wide-Area Networking Configuration
Guide: SMDS and X.25 and LAPB Cisco
IOS Release 12.4T
Americas Headquarters
Cisco Systems, Inc.
170 West Tasman Drive
San Jose, CA 95134-1706
USA
http://www.cisco.com
Tel: 408 526-4000
800 553-NETS (6387)
Fax: 408 527-0883
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CONTENTS
Wide-Area Networking Overview 1
Finding Feature Information 1
Frame Relay 1
Frame Relay-ATM Internetworking 3
Switched Multimegabit Data Service 4
Link Access Procedure - Balanced and X.25 5
Layer 2 Virtual Private Network 6
Layer 2 Tunneling Protocol Version 3 6
L2VPN Pseudowire Redundancy 6
Layer 2 Virtual Private Network Interworking 7
Layer 2 Local Switching 7
Wide Area Application Services 7
Configuring X.25 and LAPB 9
Finding Feature Information 9
Information about LAPB and X.25 10
LAPB Overview 10
LAPB Data Compression 10
Modifying LAPB Protocol Parameters 11
Configuring Priority and Custom Queueing for LAPB 12
X.25 Interfaces 13
X.25 Encapsulation 13
Virtual Circuit Ranges 13
Packet-Numbering Modulo 14
X.121 Address 14
X.25 Switch Local Acknowledgment 15
Flow Control Parameter Negotiation 15
Default Flow Control Values 16
Asymmetrical Flow Control 16
X.25 Interface Parameters 17
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X.25 Failover 17
X.25 Level 3 Timers 17
X.25 Addresses 17
Interface Alias Address 18
Suppressing or Replacing the Calling Address 18
Suppressing the Called Address 18
Default VC Protocol 19
Disabling PLP Restarts 19
X.25 Datagram Transport 19
Overview 19
Point-to-Point and Multipoint Subinterfaces 20
Mapping Protocol Addresses to X.121 Addresses 20
Understanding Protocol Encapsulation for Single-Protocol and Multiprotocol VCs 21
Understanding Protocol Identification 21
Mapping Datagram Addresses to X.25 Hosts 22
PAD Access 23
Encapsulation PVC 24
X.25 TCP IP Header Compression 24
X.25 Bridging 24
Additional X.25 Datagram Transport Features 24
X.25 Payload Compression 24
Establishing the Packet Acknowledgment Policy 25
X.25 User Facilities 25
X.25 Routing 26
X.25 Route 26
Additional X.25 Routing Features 27
X.25 Load Balancing 27
XOT to Use Interface Default Flow Control Values 28
Calling Address Interface-Based Insertion and Removal 28
DNS-Based X.25 Routing 28
Overview 29
Address Resolution 30
Mnemonic Resolution 31
X.25 over Frame Relay (Annex G) 32
CMNS Routing 32
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Priority Queueing or Custom Queueing for X.25 32
X.25 Closed User Groups 33
Closed User Group 33
Understanding CUG Configuration 35
Point of Presence 36
CUG Membership Selection 36
CUG Service Access and Properties 37
POP with No CUG Access 37
POP with Access Restricted to One CUG 38
POP with Multiple CUGs and No Public Access 38
POP with Multiple CUGs and Public Access 38
CUG Selection Facility Suppression 38
DDN or BFE X.25 39
DDN 39
Understanding DDN X.25 Dynamic Mapping 39
IP Precedence Handling 40
Blacker Front End X.25 40
X.25 Remote Failure Detection 40
X.29 Access Lists 42
How to Configure LAPB 42
Configuring a LAPB Datagram Transport 43
Selecting an Encapsulation and Protocol 43
Configuring Compression over LAPB 43
Configuring Compression over Multi-LAPB 44
Configuring Transparent Bridging over Multiprotocol LAPB 44
How to Configure X.25 45
Configuring an X.25 Interface 46
Configuring X.25 Encapsulation 46
Setting the Virtual Circuit Ranges 46
Setting the Packet-Numbering Modulo 47
Setting the X.121 Address 47
Configuring X.25 Switch Local Acknowledgment 47
Verifying Local Acknowledgement 47
Enabling Flow Control Parameter Negotiation 48
Verifying Flow Control Parameter Negotiation 48
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Setting Default Flow Control Values 48
Setting Default Window Sizes 48
Setting Default Packet Sizes 49
Enabling Asymmetrical Flow Control 49
Configuring Additional X.25 Interface Parameters 49
Configuring X.25 Failover 50
Configuring X.25 Failover on an Interface 50
Configuring X.25 Failover on an X.25 Profile 50
Verifying X.25 Failover 51
Configuring the X.25 Level 3 Timers 51
Configuring X.25 Addresses 51
Configuring an Interface Alias Address 52
Suppressing or Replacing the Calling Address 52
Suppressing the Called Address 52
Establishing a Default VC Protocol 52
Disabling PLP Restarts 52
Configuring an X.25 Datagram Transport 53
Configuring Point-to-Point and Multipoint Subinterfaces 53
Mapping Protocol Addresses to X.121 Addresses 53
Mapping Datagram Addresses to X.25 Hosts 53
Configuring PAD Access 54
Establishing an Encapsulation PVC 54
Setting X.25 TCP IP Header Compression 54
Configuring X.25 Bridging 54
Configuring Additional X.25 Datagram Transport Features 55
Configuring X.25 Payload Compression 55
Configuring the Encapsulation VC Idle Time 55
Increasing the Number of VCs Allowed 56
Configuring the Ignore Destination Time 56
Establishing the Packet Acknowledgment Policy 56
Configuring X.25 User Facilities 56
Defining the VC Packet Hold Queue Size 58
Restricting Map Usage 59
Configuring X.25 Routing 59
Enabling X.25 Routing 59
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Configuring an X.25 Route 59
Configuring a PVC Switched Between X.25 Interfaces 61
Configuring a Locally Switched PVC 61
Ensuring the TCP sessions are Connected 61
Configuring X.25 Switching Between PVCs and SVCs 62
Displaying the Switched Information 62
Configuring Additional X.25 Routing Features 62
Configuring X.25 Load Balancing 62
Verifying X.25 Load Balancing 63
Configuring XOT to Use Interface Default Flow Control Values 63
Configuring Calling Address Interface-Based Insertion and Removal 63
Verifying Interface-Based Calling Address Insertion 64
Substituting Addresses in an X.25 Route 64
Configuring XOT Alternate Destinations 65
Configuring DNS-Based X.25 Routing 65
Verifying DNS-Based X.25 Routing 66
Verifying DNS-Based X.25 Mnemonic Resolution 66
Configuring X.25 over Frame Relay (Annex G) 67
Configuring CMNS Routing 67
Enabling CMNS on an Interface 68
Configuring a Route to a CMNS Host 68
Configuring Priority Queueing or Custom Queueing for X.25 68
Configuring X.25 Closed User Groups 69
Configuring X.25 CUG Service Access and Properties 69
Configuring a POP with No CUG Access 69
Configuring a POP with Access Restricted to One CUG 70
Configuring a POP with Multiple CUGs and No Public Access 70
Configuring a POP with Multiple CUGs and Public Access 71
Configuring CUG Selection Facility Suppression 72
Configuring CUG Selection Facility Suppression on an Interface 72
Configuring CUG Selection Facility Suppression on an X.25 Profile 72
Verifying X.25 CUG Service 73
Troubleshooting Tips for X.25 CUG Service 73
Configuring DDN or BFE X.25 73
Enabling DDN X.25 74
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Defining IP Precedence Handling 74
Configuring Blacker Front End X.25 74
Configuring X.25 Remote Failure Detection 74
X.25 Remote Failure Detection with IP Static Routes 74
X.25 Remote Failure Detection and the Backup Interface 75
Verifying X.25 Remote Failure Detection 77
Creating X.29 Access Lists 77
Creating an X.29 Access List 77
Applying an Access List to a Virtual Terminal Line 78
Creating an X.29 Profile Script 78
Monitoring and Maintaining LAPB and X.25 78
X.25 and LAPB Configuration Examples 79
Typical LAPB Configuration Example 80
Transparent Bridging for Multiprotocol LAPB Encapsulation Example 80
Typical X.25 Configuration Example 80
VC Ranges Example 82
X.25 Failover Example 82
PVC Switching on the Same Router Example 82
X.25 Route Address Pattern Matching Example 82
X.25 Routing Examples 83
PVC Used to Exchange IP Traffic Example 84
Point-to-Point Subinterface Configuration Example 84
Simple Switching of a PVC over XOT Example 85
PVC Switching over XOT Example 85
X.25 Load Balancing Examples 86
X.25 Load Balancing Using VC-Count Distribution Method Example 86
X.25 Load Balancing with Multiple Hunt Groups Example 86
X.25 Switching Between PVCs and SVCs Example 87
Inserting and Removing X.121 Addresses As Calls Are Routed Example 88
Forwarding Calls Using the continue Keyword Example 88
X.25 Routing Statements Before continue Keyword 89
Same X.25 Network Configuration with continue Keyword 89
DNS-Based X.25 Routing Example 90
X.25overFrameRelayAnnexGExample 90
CMNS Switching Example 91
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CMNS Switching over a PDN Example 92
CMNS Switched over Leased Lines Example 93
Configuring Local Acknowledgment Example 94
Setting Asymmetrical Window and Packet Sizes Flow Control Never Example 94
Configuring Flow Control Always Example 95
X.25 CUGs Examples 96
X.25 CUG Service and Access with CUG Properties Example 96
POP with No CUG Access Example 96
POP with Access Restricted to One CUG Example 97
POPwithMultipleCUGsandNoPublicAccessExample 97
POP with Multiple CUGs and Public Access Example 97
CUG Selection Facility Suppression for the Preferential CUG Example 98
CUG Selection Facility Suppression for All CUGs Example 98
DDN X.25 Configuration Example 98
Blacker Front End Example 99
X.25 Ping Support over Multiple Lines Example 99
Booting from a Network Server over X.25 Example 100
X.25 Remote Failure Detection Examples 100
X.25 Remote Failure Detection with IP Static Routes Example 100
X.25 Remote Failure Detection and the Backup Interface Example 101
X.29 Access List Example 101
X.29 Profile Script Example 102
Terminal Line Security for PAD Connections 103
Finding Feature Information 103
Prerequisites for Terminal Line Security for PAD Connections 103
Restrictions for Terminal Line Security for PAD Connections 103
Information About Terminal Line Security for PAD Connections 104
Security Considerations 104
PAD Call Behavior When a Line Is Configured for CUG Subscription 104
PAD Call Behavior When Only the Line is Configured for CUG Service 105
PAD Call Behavior When Both a Line and an Interface Are Configured for CUG Service 106
Benefits 107
How to Configure Terminal Line Security for PAD Connections 107
Configuring X.25 CUG Support on Terminal Lines 107
Verifying X.25 CUG Support on Terminal Lines 108
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Monitoring and Maintaining X.25 CUG Support on Terminal Lines 109
Configuration Examples for Terminal Line Security for PAD Connections 110
Configuring X.25 CUG Support on Terminal Lines Example 110
Additional References 110
Feature Information for Terminal Line Security for PAD Connections 111
Glossary 112
X.25 Annex G Session Status Change Reporting 115
Finding Feature Information 115
Feature Overview 115
Benefits 116
Restrictions 116
Related Documents 116
Supported Platforms 116
Supported Standards and MIBs and RFCs 116
Prerequisites 117
Configuration Tasks 117
Enabling X.25 Annex G Session Status Change Reporting 117
Verifying X.25 Annex G Session Status Change Reporting 117
Configuration Examples 117
X.25 Annex G Session Status Change Reporting Configuration Example 118
X.25 Dual Serial Line Management 119
Finding Feature Information 119
Feature Overview 119
Benefits 121
Restrictions 121
Related Documents 121
Supported Standards and MIBs and RFCs 121
Configuration Tasks 122
Configuring X.25 Dual Serial Line Management 122
Verifying X.25 Dual Serial Line Management 123
Troubleshooting Tips 124
Monitoring and Maintaining X.25 Dual Serial Line Management 124
X.25 Dual Serial Line Management Configuration Example 124
Glossary 125
X.25 over TCP Profiles 127
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Finding Feature Information 127
Feature Overview 127
X.25 over TCP Profiles Functional Description 128
XOT Access Groups 128
X.25 Profiles for XOT 129
Application of X.25 Profiles on XOT Switched Virtual Circuits 129
Application of X.25 Profiles on Remote Switched XOT Permanent Virtual Circuits 129
Benefits 129
Restrictions 130
Related Documents 130
Supported Platforms 130
Supported Standards and MIBs and RFCs 131
Prerequisites 131
Configuration Tasks 132
Configuring an XOT Access Group 132
Verifying XOT Access Groups 132
Troubleshooting Tips 133
Configuration Examples 133
Unrestricted XOT Access with Defined X.25 Parameters for All XOT Connections Example 134
Restricted XOT Access with Default X.25 Parameters for All XOT Connections Example 134
Restricted XOT Access with Multiple X.25 Parameter Configurations Example 134
Glossary 135
X.25 Record Boundary Preservation for Data Communications Networks 137
Finding Feature Information 137
Feature Overview 137
When to Use Record Boundary Preservation 138
How Record Boundary Preservation Works 138
Benefits 140
Restrictions 140
Related Documents 140
Supported Standards and MIBs and RFCs 140
Prerequisites 141
Configuration Tasks 141
Configuring a PVC to Use RBP for Incoming X.25 Connections 141
Configuring SVCs to Use RBP for Incoming X.25 Connections 141
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Configuring a PVC to Use RBP for Incoming TCP Connections 142
Configuring SVCs to Use RBP for Incoming TCP Connections 143
Verifying Record Boundary Preservation 143
Monitoring and Maintaining RBP 145
Configuration Examples 145
PVC Configured to Use RBP for Incoming X.25 Connections Example 145
SVCs Configured to Use RBP for Incoming X.25 Connections Example 146
PVC Configured to Use RBP for Incoming TCP Connections Example 146
SVCs Configured to Use RBP for Incoming TCP Connections Example 146
Glossary 146
X.25 Suppression of Security Signaling Facilities 149
Finding Feature Information 150
Information About the X.25 Suppression of Security Signaling Facilities Feature 150
X.25 Security Facilities Suppression Scenarios 150
When Suppressing the Security Signaling Facilities Is Necessary 151
How to Suppress the X.25 Security Signaling Facilities 152
Disabling the X.25 Security Signaling Facilities 152
Troubleshooting Tips 154
Configuration Example for Suppressing X.25 Security Signaling Facilities 154
Additional References 154
X.25 Call Confirm Packet Address Control 157
Finding Feature Information 157
Information About X.25 Call Confirm Packet Address Control 157
Address Encoding in X.25 Call Confirm Packets 158
X.25 Call Confirm Packet Address Control 158
Benefits of X.25 Call Confirm Packet Address Control 159
How to Configure X.25 Call Confirm Packet Address Control 159
Configuring X.25 Call Confirm Packet Address Control on an Interface 159
Troubleshooting Tips 160
Configuring X.25 Call Confirm Packet Address Control in an X.25 Profile 160
Troubleshooting Tips 161
Configuration Examples for X.25 Call Confirm Packet Address Control 162
Suppressing Addresses in Call Confirm Packets Example 162
Using Addresses from Original Call Packets in the Call Confirm Packets Example 162
Additional References 162
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Feature Information for X.25 Call Confirm Packet Address Control 163
X.25 Data Display Trace 165
Finding Feature Information 165
Displaying the Contents of X.25 Packets 165
Additional References 167
Feature Information for X.25 Data Display Trace 167
X.25 Version Configuration 169
Finding Feature Information 169
Information About X.25 Version Configuration 170
X.25 Version Configuration 170
Typical Uses of the x25 version Command 170
Description of Cisco IOS X.25 Behavior Sets 171
Cisco IOS Implementation of the 1980 X.25 Behavior Set 171
Cisco IOS Implementation of the 1984 X.25 Behavior Set 172
Cisco IOS Implementation of the 1988 X.25 Behavior Set 172
Cisco IOS Implementation of the 1993 X.25 Behavior Set 173
X.25 Facility Support 173
How to Specify the X.25 Version 178
Specifying the X.25 Behavior Set to Be Used by an Interface or X.25 Profile 178
Verifying the X.25 Behavior Set for an Interface or X.25 Profile 179
Configuration Examples for X.25 Version Configuration 180
Specifying the X.25 Version to Be Used by an Interface in a Hunt Group Example 181
Specifying the X.25 Version to Be Used by Both Interfaces in a Hunt Group Example 181
Verifying the X.25 Version for an Interface or X.25 Profile 182
Additional References 183
X.25 Station Type for ISDN D-channel Interface 185
Finding Feature Information 186
Prerequisites for X.25 Station Type for ISDN D-channel Interface 186
Information About X.25 Station Type for ISDN D-channel Interface 186
Configuring X.25 on ISDN D-channel Interface 186
X.25 Closed User Groups 187
How to Configure X.25 Encapsulation on ISDN BRI D-channel Interface 187
Configuring X.25 Encapsulation on ISDN BRI D-channel Interface 187
Configuration Examples for X.25 Encapsulation on ISDN BRI D-channel Interface 189
X.25 Encapsulation on an ISDN BRI D-channel Interface Example 189
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Additional References 190
X.25 Throughput Negotiation 193
Finding Feature Information 193
Restrictions for X.25 Throughput Negotiation 193
Information about X.25 Throughput Negotiation 194
How to Configure X.25 Throughput Negotiation 198
Configuring X.25 Throughput Negotiation 198
Configuration Examples for X.25 Throughput Negotiation 200
Basic example 200
Never example 200
Additional References 201
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Wide-Area Networking Overview
Cisco IOS software provides a range of wide-area networking capabilities to fit almost every network
environment need. Cisco offers cell relay via the Switched Multimegabit Data Service (SMDS), circuit
switching via ISDN, packet switching via Frame Relay, and the benefits of both circuit and packet
switching via Asynchronous Transfer Mode (ATM). LAN emulation (LANE) provides connectivity
between ATM and other LAN types. The Cisco IOS Wide-Area Networking Configuration Guide presents
a set of general guidelines for configuring the following software components:
This module gives a high-level description of each technology. For specific configuration information, see
the appropriate module.
•
•
•
•
•
•
Finding Feature Information, page 1
Frame Relay, page 1
Switched Multimegabit Data Service, page 4
Link Access Procedure - Balanced and X.25, page 5
Layer 2 Virtual Private Network, page 6
Wide Area Application Services, page 7
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest feature
information and caveats, see the release notes for your platform and software release. To find information
about the features documented in this module, and to see a list of the releases in which each feature is
supported, see the Feature Information Table at the end of this document.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support.
To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Frame Relay
The Cisco Frame Relay implementation currently supports routing on IP, DECnet, AppleTalk, XNS,
Novell IPX, CLNS, Banyan VINES, and transparent bridging.
Although Frame Relay access was originally restricted to leased lines, dialup access is now supported. For
more information, for dialer profiles or for legacy dial-on-demand routing (DDR) see the see the module
Dial-on-Demand Routing Configuration.
To install software on a new router or access server by downloading software from a central server over an
interface that supports Frame Relay, see the module Loading and Maintaining System Images.
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Frame Relay
To configure access between Systems Network Architecture (SNA) devices over a Frame Relay network,
see the module Configuring SNA Frame Relay Access Support.
The Frame Relay software provides the following capabilities:
•
Support for the three generally implemented specifications of Frame Relay Local Management
Interfaces (LMIs):
◦
•
•
•
The Frame Relay Interface joint specification produced by Northern Telecom, Digital Equipment
Corporation, StrataCom, and Cisco Systems
◦ The ANSI-adopted Frame Relay signal specification, T1.617 Annex D
◦ The ITU-T-adopted Frame Relay signal specification, Q.933 Annex A
Conformity to ITU-T I-series (ISDN) recommendation as I122, "Framework for Additional Packet
Mode Bearer Services":
◦ The ANSI-adopted Frame Relay encapsulation specification, T1.618
◦ The ITU-T-adopted Frame Relay encapsulation specification, Q.922 Annex A
Conformity to Internet Engineering Task Force (IETF) encapsulation in accordance with RFC 2427,
except bridging.
Support for a keepalive mechanism, a multicast group, and a status message, as follows:
◦
•
The keepalive mechanism provides an exchange of information between the network server and
the switch to verify that data is flowing.
◦ The multicast mechanism provides the network server with a local data-link connection identifier
(DLCI) and a multicast DLCI. This feature is specific to our implementation of the Frame Relay
joint specification.
◦ The status mechanism provides an ongoing status report on the DLCIs known by the switch.
Support for both PVCs and SVCs in the same sites and routers.
SVCs allow access through a Frame Relay network by setting up a path to the destination endpoints only
when the need arises and tearing down the path when it is no longer needed.
•
Support for Frame Relay Traffic Shaping beginning with Cisco IOS Release 11.2. Traffic shaping
provides the following:
◦
•
•
•
Rate enforcement for individual circuits--The peak rate for outbound traffic can be set to the
committed information rate (CIR) or some other user-configurable rate.
◦ Dynamic traffic throttling on a per-virtual-circuit basis--When backward explicit congestion
notification (BECN) packets indicate congestion on the network, the outbound traffic rate is
automatically stepped down; when congestion eases, the outbound traffic rate is stepped up again.
◦ Enhanced queueing support on a per-virtual circuit basis--Custom queueing, priority queueing,
and weighted fair queueing can be configured for individual virtual circuits.
Transmission of congestion information from Frame Relay to DECnet Phase IV and CLNS. This
mechanism promotes forward explicit congestion notification (FECN) bits from the Frame Relay layer
to upper-layer protocols after checking for the FECN bit on the incoming DLCI. Use this Frame Relay
congestion information to adjust the sending rates of end hosts. FECN-bit promotion is enabled by
default on any interface using Frame Relay encapsulation. No configuration is required.
Support for Frame Relay Inverse ARP as described in RFC 1293 for the AppleTalk, Banyan VINES,
DECnet, IP, and IPX protocols, and for native hello packets for DECnet, CLNP, and Banyan VINES.
It allows a router running Frame Relay to discover the protocol address of a device associated with the
virtual circuit.
Support for Frame Relay switching, whereby packets are switched based on the DLCI--a Frame Relay
equivalent of a Media Access Control (MAC)-level address. Routers are configured as a hybrid DTE
switch or pure Frame Relay DCE access node in the Frame Relay network.
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Frame Relay-ATM Internetworking
Frame Relay
Frame Relay switching is used when all traffic arriving on one DLCI can be sent out on another DLCI to
the same next-hop address. In such cases, the Cisco IOS software need not examine the frames individually
to discover the destination address, and, as a result, the processing load on the router decreases.
The Cisco implementation of Frame Relay switching provides the following functionality:
•
•
•
•
•
◦ Switching over an IP tunnel
◦ Switching over Network-to-Network Interfaces (NNI) to other Frame Relay switches
◦ Local serial-to-serial switching
◦ Switching over ISDN B channels
◦ Traffic shaping on switched PVCs
◦ Congestion management on switched PVCs
◦ Traffic policing on User-Network Interface (UNI) DCE
◦ FRF.12 fragmentation on switched PVCs
Support for subinterfaces associated with a physical interface. The software groups one or more PVCs
under separate subinterfaces, which in turn are located under a single physical interface. See the
Configuring Frame Relay module.
Support for fast-path transparent bridging, as described in RFC 1490, for Frame Relay encapsulated
serial and High-Speed Serial Interfaces (HSSIs) on all platforms.
Support of the Frame Relay DTE MIB specified in RFC 1315. However, the error table is not
implemented. To use the Frame Relay MIB, refer to your MIB publications.
Support for Frame Relay fragmentation. Cisco has developed the following three types of Frame Relay
fragmentation:
◦
End-to-End FRF.12 Fragmentation
FRF.12 fragmentation is defined by the FRF.12 Implementation Agreement. This standard was developed
to allow long data frames to be fragmented into smaller pieces (fragments) and interleaved with real-time
frames. End-to-end FRF.12 fragmentation is recommended for use on PVCs that share links with other
PVCs that are transporting voice and on PVCs transporting Voice over IP (VoIP).
•
◦
Frame Relay Fragmentation Using FRF.11 Annex C
When VoFR (FRF.11) and fragmentation are both configured on a PVC, the Frame Relay fragments are
sent in the FRF.11 Annex C format. This fragmentation is used when FRF.11 voice traffic is sent on the
PVC, and it uses the FRF.11 Annex C format for data.
See the module Configuring Voice over Frame Relay in the Cisco IOS Voice, Video, and Fax
Configuration Guide for configuration tasks and examples for Frame Relay fragmentation using FRF.11
Annex C.
•
◦
Cisco Proprietary Fragmentation
Cisco proprietary fragmentation is used on data packets on a PVC that is also used for voice traffic.
See the module Configuring Voice over Frame Relay in the Cisco IOS Voice, Video, and Fax
Configuration Guide for configuration tasks and examples for Cisco proprietary fragmentation.
•
Frame Relay-ATM Internetworking, page 3
Frame Relay-ATM Internetworking
Cisco IOS software supports the Frame Relay Forum implementation agreements for Frame Relay-ATM
Interworking. Frame Relay-ATM Interworking enables Frame Relay and ATM networks to exchange data,
despite differing network protocols. There are two types of Frame Relay-ATM Interworking:
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Wide-Area Networking Overview
Switched Multimegabit Data Service
FRF.5 Frame Relay-ATM Network Interworking
FRF.5 provides network interworking functionality that allows Frame Relay end users to communicate
over an intermediate ATM network that supports FRF.5. Multiprotocol encapsulation and other higherlayer procedures are transported transparently, just as they would be over leased lines.
FRF.5 describes network interworking requirements between Frame Relay Bearer Services and Broadband
ISDN (BISDN) permanent virtual circuit (PVC) services.
The FRF.5 standard is defined by the Frame Relay Forum Document Number FRF.5: Frame Relay/ATM
PVC Network Interworking Implementation Agreement. For information about which sections of this
implementation agreement are supported by Cisco IOS software, see Frame Relay-ATM Interworking
Supported Standards.
FRF.8 Frame Relay-ATM Service Interworking
FRF.8 provides service interworking functionality that allows a Frame Relay end user to communicate with
an ATM end user. Traffic is translated by a protocol converter that provides communication among
dissimilar Frame Relay and ATM equipment.
FRF.8 describes a one-to-one mapping between a Frame Relay PVC and an ATM PVC.
The FRF.8 standard is defined by the Frame Relay Forum Document Number FRF.8: Frame Relay/ATM
PVC Network Service Interworking Implementation Agreement. For information about which sections of
this implementation agreement are supported by Cisco IOS software, see Frame Relay-ATM Interworking
Supported Standards.
Switched Multimegabit Data Service
The Cisco implementation of the SMDS protocol is based on cell relay technology as defined in the
Bellcore Technical advisories, which are based on the IEEE 802.6 standard. We provide an interface to an
SMDS network using DS1 or DS3 high-speed transmission facilities. Connection to the network is made
through a device called an SDSU--an SMDS digital service unit (DSU). The SDSU attaches to a router or
access server through a serial port. On the other side, the SDSU terminates the line.
The implementation of SMDS supports the IP, DECnet, AppleTalk, XNS, Novell IPX, Banyan VINES, and
OSI internetworking protocols, and transparent bridging.
The implementation of SMDS also supports SMDS encapsulation over an ATM interface. For more
information and for configuration tasks, see Configuring ATM.
Routing of AppleTalk, DECnet, IP, IPX, and ISO CLNS is fully dynamic; that is, the routing tables are
determined and updated dynamically. Routing of the other supported protocols requires that you establish a
static routing table of SMDS neighbors in a user group. Once this table is set up, all interconnected routers
and access servers provide dynamic routing.
Note
When configuring IP routing over SMDS, you may need to make adjustments to accommodate split
horizon effects. Refer to the Configuring EIGRP module for information about how Cisco software handles
possible split horizon conflicts. By default, split horizon is disabled for SMDS networks.
The SMDS implementation includes multiple logical IP subnetworks support as defined by RFC 1209. This
RFC describes routing IP over an SMDS cloud in which each connection is considered a host on one
specific private network, and points to cases where traffic must transit from network to network.
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
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Wide-Area Networking Overview
Link Access Procedure - Balanced and X.25
The implementation of SMDS also provides the Data Exchange Interface (DXI) Version 3.2 with
heartbeat . The heartbeat mechanism periodically generates a heartbeat poll frame.
When a multicast address is not available to a destination, pseudobroadcasting can be enabled to broadcast
packets to those destinations using a unicast address.
Link Access Procedure - Balanced and X.25
X.25 is one of a group of specifications published by the ITU-T. These specifications are international
standards that are formally called Recommendations . The ITU-T Recommendation X.25 defines how
connections between DTE and DCE are maintained for remote terminal access and computer
communications. The X.25 specification defines protocols for two layers of the Open Systems
Interconnection (OSI) reference model. The data link layer protocol defined is LAPB. The network layer is
sometimes called the packet level protocol (PLP), but is commonly (although less correctly) referred to as
the X.25 protocol.
The ITU-T updates its Recommendations periodically. The specifications dated 1980 and 1984 are the most
common versions currently in use. Additionally, the International Standards Organization (ISO) has
published ISO 7776:1986 as an equivalent to the LAPB standard, and ISO 8208:1989 as an equivalent to
the ITU-T 1984 Recommendation X.25 packet layer. The Cisco X.25 software follows the ITU-T 1984
Recommendation X.25 , except for its Defense Data Network (DDN) and Blacker Front End (BFE)
operation, which follow the ITU-T 1980 Recommendation X.25 .
Note
The ITU-T carries out the functions of the former CCITT. The 1988 X.25 standard was the last published
as a CCITT Recommendation . The first ITU-T Recommendation is the 1993 revision.
In addition to providing remote terminal access, The Cisco X.25 software provides transport for LAN
protocols--IP, DECnet, XNS, ISO CLNS, AppleTalk, Novell IPX, Banyan VINES, and Apollo Domain-and bridging.
Cisco IOS X.25 software provides the following capabilities:
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LAPB datagram transport--LAPB is a protocol that operates at Level 2 (the data link layer) of the OSI
reference model. It offers a reliable connection service for exchanging data (in units called frames )
with one other host. The LAPB connection is configured to carry a single protocol or multiple
protocols. Protocol datagrams (IP, DECnet, AppleTalk, and so forth) are carried over a reliable LAPB
connection, or datagrams of several of these protocols are encapsulated in a proprietary protocol and
carried over a LAPB connection. Cisco also implements transparent bridging over multiprotocol
LAPB encapsulations on serial interfaces.
X.25 datagram transport-- X.25 can establish connections with multiple hosts; these connections are
called virtual circuits. Protocol datagrams (IP, DECnet, AppleTalk, and so forth) are encapsulated
inside packets on an X.25 virtual circuit. Mappings between the X.25 address of a host and its
datagram protocol addresses enable these datagrams to be routed through an X.25 network, thereby
permitting an X.25 PDN to transport LAN protocols.
X.25 switch--X.25 calls can be routed based on their X.25 addresses either between serial interfaces on
the same router (local switching) or across an IP network to another route r, using X.25 over TCP
(XOT). XOT encapsulates the X.25 packet level inside a TCP connection, allowing X.25 equipment to
be connected via a TCP/IP-based network. The Cisco X.25 switching features provide a convenient
way to connect X.25 equipment, but do not provide the specialized features and capabilities of an X.25
PDN.
ISDN D channel--X.25 traffic over the D channel, using up to 9.6 kbps bandwidth, can be used to
support many applications. For example, it may be required as a primary interface where low volume
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
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Layer 2 Tunneling Protocol Version 3
Layer 2 Virtual Private Network
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sporadic interactive traffic is the normal mode of operation. For information on how to configure X.25
on ISDN, refer to the modules Configuring X.25 on ISDN and Configuring X.25 on ISDN Using
AO/DI.
PAD--User sessions can be carried across an X.25 network using the packet assembler/disassembler
(PAD) protocols defined by the ITU-T Recommendations X.3 and X.29.
QLLC--The Cisco IOS software can use the Qualified Logical Link Control (QLLC) protocol to carry
SNA traffic through an X.25 network.
Connection-Mode Network Service (CMNS)--CMNS is a mechanism that uses OSI-based network
service access point (NSAP) addresses to extend local X.25 switching to nonserial media (for example,
Ethernet, FDDI, and Token Ring). This implementation provides the X.25 PLP over Logical Link
Control, type 2 (LLC2) to allow connections over nonserial interfaces. The Cisco CMNS
implementation supports services defined in ISO Standards 8208 (packet level) and 8802-2 (frame
level).
DDN and BFE X.25--The DDN-specified Standard Service is supported. The DDN X.25 Standard
Service is the required protocol for use with DDN Packet-Switched Nodes (PSNs). The Defense
Communications Agency (DCA) has certified the Cisco DDN X.25 Standard Service implementation
for attachment to the DDN. The Cisco DDN implementation also includes Blacker Front End
operation.
X.25 MIB--Subsets of the specifications in SNMP MIB Extension for X.25 LAPB (RFC 1381) and
SNMP MIB Extension for the X.25 Packet Layer (RFC 1382) are supported. The LAPB XID Table, X.
25 Cleared Circuit Table, and X.25 Call Parameter Table are not implemented. All values are readonly. To use the X.25 MIB, refer to the RFCs.
Closed User Groups (CUGs)--A CUG is a collection of DTE devices for which the network controls
access between two members and between a member and a nonmember. An X.25 network can support
up to 10,000 CUGs. CUGs allow various network subscribers (DTE devices) to be segregated into
private subnetworks that have limited incoming or outgoing access.
The Cisco X.25 implementation does not support fast switching.
Layer 2 Virtual Private Network
L2VPN services are point-to-point. They provide Layer 2 point-to-point connectivity over either an MPLS
or a pure IP (L2TPv3) core.
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Layer 2 Tunneling Protocol Version 3, page 6
L2VPN Pseudowire Redundancy, page 6
Layer 2 Virtual Private Network Interworking, page 7
Layer 2 Local Switching, page 7
Layer 2 Tunneling Protocol Version 3
The Layer 2 Tunneling Protocol Version 3 feature expands Cisco's support of Layer 2 VPNs. Layer 2
Tunneling Protocol Version 3 (L2TPv3) is an IETF l2tpext working group draft that provides several
enhancements to L2TP to tunnel any Layer 2 payload over L2TP. Specifically, L2TPv3 defines the L2TP
protocol for tunneling Layer 2 payloads over an IP core network by using Layer 2 VPNs.
L2VPN Pseudowire Redundancy
L2VPNs can provide pseudowire resiliency through their routing protocols. When connectivity between
end-to-end PE routers fails, an alternative path to the directed LDP session and the user data can take over.
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Layer 2 Virtual Private Network Interworking
Wide Area Application Services
However, there are some parts of the network where this rerouting mechanism does not protect against
interruptions in service. The L2VPN Pseudowire Redundancy feature provides the ability to ensure that the
CE2 router in can always maintain network connectivity, even if one or all the failures in the figure occur.
The L2VPN Pseudowire Redundancy feature enables you to set up backup pseudowires. You can configure
the network with redundant pseudowires (PWs) and redundant network elements.
Layer 2 Virtual Private Network Interworking
Layer 2 transport over MPLS and IP already exists for like-to-like attachment circuits, such as Ethernet-toEthernet or PPP-to-PPP. L2VPN Interworking builds on this functionality by allowing disparate attachment
circuits to be connected. An interworking function facilitates the translation between the different Layer 2
encapsulations. The L2VPN Interworking feature supports Ethernet, 802.1Q (VLAN), Frame Relay, ATM
AAL5, and PPP attachment circuits over MPLS and L2TPv3.
Layer 2 Local Switching
Local switching allows you to switch Layer 2 data between two interfaces of the same type (for example,
ATM to ATM, or Frame Relay to Frame Relay) or between interfaces of different types (for example,
Frame Relay to ATM) on the same router. The interfaces can be on the same line card or on two different
cards. During these kinds of switching, the Layer 2 address is used, not any Layer 3 address. Same-port
local switching allows you to switch Layer 2 data between two circuits on the same interface.
Wide Area Application Services
Cisco's WAAS Express software interoperates with WAN optimization headend applications from Cisco
and improves WAN access and use by optimizing applications that require high bandwidth or are bound to
a LAN, such as backup.
WAAS Express helps enterprises meet the following objectives:
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Complements the Cisco WAN optimization system by adding the capability to the branch routers.
Provide branch office employees with LAN-like access to information and applications across a
geographically distributed network.
Minimize unnecessary WAN bandwidth consumption through the use of advanced compression
algorithms.
Virtualize print and other local services to branch office users.
Improve application performance over the WAN by addressing the following common issues:
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Low data rates (constrained bandwidth)
Slow delivery of frames (high network latency)
Higher rates of packet loss (low reliability)
The Network Analysis Module (NAM) Performance Agent (PA) for WAAS Express analyzes and
measures network traffic. The PA enables baselining, monitoring, and troubleshooting of application
performance. The analysis and measurement of network traffic is done by the Measurement, Aggregation,
and Correlation Engine (MACE). MACE performs the required measurements on a subset of traffic and
exports the necessary metrics to a target.
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
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Wide-Area Networking Overview
Cisco and the Cisco Logo are trademarks of Cisco Systems, Inc. and/or its affiliates in the U.S. and other
countries. A listing of Cisco's trademarks can be found at www.cisco.com/go/trademarks. Third party
trademarks mentioned are the property of their respective owners. The use of the word partner does not
imply a partnership relationship between Cisco and any other company. (1005R)
Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be
actual addresses and phone numbers. Any examples, command display output, network topology diagrams,
and other figures included in the document are shown for illustrative purposes only. Any use of actual IP
addresses or phone numbers in illustrative content is unintentional and coincidental.
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
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Configuring X.25 and LAPB
This chapter describes how to configure connections through Link Access Procedure, Balanced (LAPB)
connections and X.25 networks. LAPB tasks are presented first for users who only want to configure a
simple, reliable serial encapsulation method. For a complete description of the commands mentioned in
this chapter, refer to the chapter "X.25 and LAPB Commands " in the Cisco IOS Wide-Area Networking
Command Reference.
For information on the following related topics, see the corresponding Cisco publications:
Resource
Configuring PAD access
"Configuring the Cisco PAD Facility for X.25
Connections" chapter in the Cisco IOS Terminal
Services Configuration Guide
Translating between an X.25 PAD connection and
another protocol
Cisco IOS Terminal Services Command
Reference (commands in alphabetical order.
Configuring X.25 traffic over an ISDN D channel
"Configuring X.25 on ISDN" and "Configuring
X.25 on ISDN using Always On/Direct ISDN
(AO/DI)" chapters in the Cisco IOS Dial
Technologies Configuration Guide
Referencing a complete list of Dial commands
Cisco IOS Dial Technologies Command
Reference (commands in alphabetical order)
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Task
Finding Feature Information, page 9
Information about LAPB and X.25, page 10
How to Configure LAPB, page 42
How to Configure X.25, page 45
X.25 and LAPB Configuration Examples, page 79
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest feature
information and caveats, see the release notes for your platform and software release. To find information
about the features documented in this module, and to see a list of the releases in which each feature is
supported, see the Feature Information Table at the end of this document.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support.
To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
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LAPB Overview
Information about LAPB and X.25
Information about LAPB and X.25
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LAPB Overview, page 10
LAPB Data Compression, page 10
Modifying LAPB Protocol Parameters, page 11
Configuring Priority and Custom Queueing for LAPB, page 12
X.25 Interfaces, page 13
Asymmetrical Flow Control, page 16
X.25 Interface Parameters, page 17
X.25 Datagram Transport, page 19
Additional X.25 Datagram Transport Features, page 24
X.25 Routing, page 26
Additional X.25 Routing Features, page 27
DNS-Based X.25 Routing, page 28
X.25 over Frame Relay (Annex G), page 32
CMNS Routing, page 32
Priority Queueing or Custom Queueing for X.25, page 32
X.25 Closed User Groups, page 33
DDN or BFE X.25, page 39
X.25 Remote Failure Detection, page 40
X.29 Access Lists, page 42
LAPB Overview
You use LAPB as a serial encapsulation method only if you have a private serial line. You must use one of
the X.25 packet-level encapsulations when attaching to an X.25 network.
LAPB standards distinguish between the following two types of hosts:
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Data terminal equipment (DTE)
Data circuit-terminating equipment (DCE)
At Level 2 (data link layer) in the OSI model, LAPB allows orderly and reliable exchange of data between
a DTE and a DCE device. A router using LAPB encapsulation can act as a DTE or DCE at the protocol
level, which is distinct from the hardware DTE or DCE identity.
Using LAPB under heavy traffic conditions can result in greater throughput than is possible using HighLevel Data Link Control (HDLC) encapsulation. When LAPB detects a missing frame, the router resends
the frame instead of waiting for the higher layers to recover the lost information. This behavior is useful
only if the host timers are relatively slow. In the case of quickly expiring host timers, however, LAPB
spends much time sending host retransmissions. If the line is not busy with data traffic, HDLC
encapsulation is more efficient than LAPB. When long-delay satellite links are used, for example, the
lockstep behavior of LAPB makes HDLC encapsulation the better choice.
LAPB Data Compression
You can configure point-to-point software compression on serial interfaces that use a LAPB or multiLAPB encapsulation. Compression reduces the size of a LAPB or multi-LAPB frame via lossless data
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Modifying LAPB Protocol Parameters
Information about LAPB and X.25
compression. Compression is performed in the software and can substantially affect system performance.
You should disable compression if the router CPU load exceeds 65 percent. To display the CPU load, use
the show process cpu command.
Predictor compression is recommended when the bottleneck is caused by the load on the router or access
server. Stacker compression is recommended when the bottleneck is the result of line bandwidth.
Compression is not recommended if the majority of your traffic is already compressed files. Compression
is also not recommended for line speeds greater than T1. The added processing time slows performance on
fast lines.
Modifying LAPB Protocol Parameters
LAPB specifies methods for exchanging data (frames), detecting out-of-sequence or missing frames,
retransmitting frames, and acknowledging frames. Several protocol parameters can be modified to change
LAPB protocol performance on a particular link. Because X.25 operates the Packet Level Protocol (PLP)
on top of the LAPB protocol, these tasks apply to both X.25 links and LAPB links. The parameters and
their default values are summarized in the table below. Detailed descriptions of each parameter are given
after the table.
Table 1
LAPB Parameters
Command
Purpose (LAPB Parameter)
Values or Ranges
Default
lapb modulo modulus
Sets the modulo.
8 or 128
8
lapb k window-size
Sets the window size (K).
1- (modulo minus 1) frames
7
lapb n1 bits
Sets the maximum bits per
frame (N1).
Bits (multiple of 8)
Based on hardware MTU and
protocol overhead
lapb n2 tries
Sets the count for sending
frames (N2).
1-255 tries
20
lapb t1 milliseconds
Sets the retransmission timer
(T1).
1-64000 milliseconds
3000
lapb interface-outage
milliseconds
Sets the hardware outage
period.
0 (disabled)
lapb t4 seconds
Sets the idle link period (T4).
0 (disabled)
The following sections provide more information about the LAPB parameters in the table above:
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LAPB modulo--The LAPB modulo determines the operating mode. Modulo 8 (basic mode) is widely
available because it is required for all standard LAPB implementations and is sufficient for most links.
Modulo 128 (extended mode) can achieve greater throughput on high-speed links that have a low error
rate (satellite links) by increasing the number of frames that can be sent before the sending device
must wait for acknowledgment (as configured by LAPB parameter K).
LAPB parameter K--LAPB K must be at most one less than the operating modulo. Modulo 8 links can
send seven frames before an acknowledgment must be received by the sending device; modulo 128
links can send as many as 127 frames. By default, LAPB links use the basic mode with a window of 7.
LAPB N1--When you configure a connection to an X.25 network, use the N1 parameter value set by
the network administrator. This value is the maximum number of bits in a LAPB frame, which
determines the maximum size of an X.25 packet. When you use LAPB over leased lines, the N1
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Configuring Priority and Custom Queueing for LAPB
Information about LAPB and X.25
parameter should be eight times the hardware MTU size plus any protocol overhead. The LAPB N1
range is dynamically calculated by the Cisco IOS software whenever an MTU change, a Layer 2/Layer
3 modulo change, or a compression change occurs on a LAPB interface.
Caution
The LAPB N1 parameter provides little benefit beyond the interface MTU, and can easily cause link
failures if misconfigured. Cisco recommends that you leave this parameter at its default value.
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LAPB N2--The transmit counter (N2) is the number of unsuccessful transmit attempts that are made
before the link is declared down.
LAPB T1--The retransmission timer (T1) determines how long a sent frame can remain
unacknowledged before the Cisco IOS software polls for an acknowledgment. For X.25 networks, the
retransmission timer setting should match that of the network.
For leased-line circuits, the T1 timer setting is critical because the design of LAPB assumes that a frame
has been lost if it is not acknowledged within period T1. The timer setting must be large enough to permit a
maximum-sized frame to complete one round trip on the link. If the timer setting is too small, the software
will poll before the acknowledgment frame can return, which may result in duplicated frames and severe
protocol problems. If the timer setting is too large, the software waits longer than necessary before
requesting an acknowledgment, slowing throughput.
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LAPB interface outage--Another LAPB timer function that allows brief hardware failures while the
protocol is up, without requiring a protocol reset. When a brief hardware outage occurs, the link
continues uninterrupted if the outage corrects before the specified outage period expires.
LAPB T4--The LAPB standards define a timer to detect unsignaled link failures (T4). The T4 timer
resets every time a frame is received from the partner on the link. If the T4 timer expires, a Receiver
Ready frame with the Poll bit set is sent to the partner, which is required to respond. If the partner does
not respond, the standard polling mechanism is used to determine whether the link is down. The period
of T4 must be greater than the period of T1.
For an example of configuring the LAPB T1 timer, see the section "Typical LAPB Configuration
Example, page 80".
Configuring Priority and Custom Queueing for LAPB
LAPB uses priority and custom queueing, which improves the responsiveness of a link to a given type of
traffic by specifying the handling of that type of traffic for transmission on the link.
Priority queueing is a mechanism that classifies packets based on certain criteria and then assigns packets
to one of four output queues, with high, medium, normal, or low priority.
Custom queueing similarly classifies packets, assigns them to one of ten output queues, and controls the
percentage of the available bandwidth of an interface that is used for a queue.
For example, you can use priority queueing to ensure that all Telnet traffic is processed promptly and that
Simple Mail Transfer Protocol (SMTP) traffic is sent only when there is no other traffic to send. Priority
queueing in this example can starve the non-Telnet traffic; custom queueing can be used instead to ensure
that some traffic of all categories is sent.
Both priority and custom queueing can be defined, but only one can be assigned to a given interface. To
configure priority and custom queueing for LAPB, perform these tasks in the following order:
1 Perform standard priority and custom queueing tasks except the task of assigning a priority or custom
group to the interface, as described in the chapters"Configuring Prioirity Queueing" and "Configuring
Custom Queueing" in the Cisco IOS Quality of Service Solutions Configuration Guide .
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X.25 Interfaces
X.25 Encapsulation
2 Perform standard LAPB encapsulation tasks, as specified in the section "Configuring a LAPB Datagram
Transport, page 43".
3 Assign either a priority group or a custom queue to the interface,as described in the chapters
"Configuring Prioirity Queueing" and "Configuring Custom Queueing" in the Cisco IOS Quality of
Service Solutions Configuration Guide .
The lapb hold-queue command is no longer supported, but the same functionality is provided by the
standard queue control command hold-queue size out.
X.25 Interfaces
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X.25 Encapsulation, page 13
Virtual Circuit Ranges, page 13
Packet-Numbering Modulo, page 14
X.121 Address, page 14
X.25 Switch Local Acknowledgment, page 15
Flow Control Parameter Negotiation, page 15
Default Flow Control Values, page 16
X.25 Encapsulation
A router using X.25 Level 3 encapsulation can act as a DTE or DCE protocol device (according to the
needs of your X.25 service supplier), can use DDN or BFE encapsulation, or can use the Internet
Engineering Task Force (IETF) standard encapsulation, as specified by RFC 1356.
Because the default serial encapsulation is HDLC, you must explicitly configure an X.25 encapsulation
method.
Note
We recommend that you use the no encapsulation x25 command to remove all X.25 configurations from
the interface before changing the encapsulation.
Typically a public data network (PDN) will require attachment as a DTE device. (This requirement is
distinct from the hardware interface DTE or DCE identity.) The default mode is DTE, and the default
encapsulation method is the Cisco pre-IETF method. If either DDN or BFE operation is needed, it must be
explicitly configured. For an example of configuring X.25 DTE operation, see the section "Typical X.25
Configuration Example, page 80" later in this chapter.
Virtual Circuit Ranges
X.25 maintains multiple connections--virtual circuits (VCs) or logical circuits (LCs)--over one physical
link between a DTE and a DCE device. X.25 can maintain up to 4095 VCs. A VC is identified by its
logical channel identifier (LCI) or virtual circuit number (VCN).
Note
Many documents use the terms virtual circuit and LC , VCN , LCN , and LCI interchangeably. Each of
these terms refers to the VC number.
An important part of X.25 operation is the range of VC numbers. These numbers are broken into the
following four ranges:
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Configuring X.25 and LAPB
Packet-Numbering Modulo
Permanent virtual circuits (PVCs)
Incoming-only circuits
Two-way circuits
Outgoing-only circuits
1
2
3
4
The incoming-only, two-way, and outgoing-only ranges define the VC numbers over which a switched
virtual circuit (SVC) can be established by the placement of an X.25 call, much as a telephone network
establishes a switched voice circuit when a call is placed.
The rules about DCE and DTE devices initiating calls are as follows:
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Note
Only the DCE can initiate a call in the incoming-only range.
Only the DTE can initiate a call in the outgoing-only range.
Both the DCE and DTE can initiate a call in the two-way range.
The International Telecommunication Union-Telecommunication Standardization Sector (ITU-T) functions
in place of the former Consultative Committee for International Telegraph and Telephone (CCITT). ITU-T
Recommendation X.25 defines "incoming" and "outgoing" in relation to the DTE or DCE interface role.
Cisco documentation uses the more intuitive sense. Unless the ITU-T sense is explicitly referenced, a call
received from the interface is an incomingcall and a call sent out to the interface is an outgoingcall .
There is no difference in the operation of SVCs in the different ranges except the restrictions on which
device can initiate a call. These ranges can be used to prevent one side from monopolizing the VCs, which
is important for X.25 interfaces with a small number of SVCs available. Six X.25 parameters define the
upper and lower limit of each of the three SVC ranges. These ranges cannot overlap. A PVC must be
assigned a number lower than those assigned to the SVC ranges.
Note
Because X.25 requires the DTE and DCE devices to have identical VC ranges, changes you make to the
VC range limits when the interface is up are held until X.25 restarts the packet service.
Packet-Numbering Modulo
The Cisco implementation of X.25 supports modulo 8 (default) and modulo 128 packet sequence
numbering.
Note
Because X.25 requires the DTE and DCE devices to have identical modulos, changes you make to the
modulo when the interface is up remain until X.25 restarts the packet service.
The X.25 modulo and the LAPB modulo are distinct and serve different purposes. LAPB modulo 128 (or
extended mode) can be used to achieve higher throughput across the DTE or DCE interface, which affects
only the local point of attachment. X.25 PLP modulo 128 can be used to achieve higher end-to-end
throughput for VCs by allowing more data packets to be in transit across the X.25 network.
X.121 Address
If your router does not originate or terminate calls but only participates in X.25 switching, this task is
optional. However, if your router is attached to a PDN, you must set the interface X.121 address assigned
by the X.25 network service provider. Interfaces that use the DDN or BFE mode will have an X.121
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
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Configuring X.25 and LAPB
X.25 Switch Local Acknowledgment
address generated from the interface IP address; for correct DDN or BFE operation, any such X.121
address must not be modified.
X.25 Switch Local Acknowledgment
X.25 switch local acknowledgment allows you the choice of configuring local or end-to-end
acknowledgment on your router. End-to-end acknowledgment can result in lower overall throughput and
restrictive performance because an endpoint can only have a limited number of its packets in transit at any
given time. End-to-end acknowledgment cannot send more packets until all have been acknowledged by
the transmission and receipt of the delivery-confirming packet containing the D-bit.
Local acknowledgment means that the Cisco router can send acknowledgments for packets that do not have
the D-bit set, before receiving an acknowledgment from the interface to which the packet was forwarded.
This results in higher throughput of packets because acknowledgment is sent between local hops much
faster and more efficiently than between end-to-end hops.
The figure below shows the Cisco router receiving packets from DTE A destined for DTE B. Without local
acknowledgment enabled, the router forwards packets to the X.25 network and then forwards
acknowledgments from the network back to DTE A. With local acknowledgment enabled, the router can
acknowledge packets received from DTE A before it has received acknowledgments from the network for
the forwarded packets. In this illustration, the X.25 network may also generate local acknowledgments.
Figure 1
Local Acknowledgment Between DTE A and DTE B
Flow Control Parameter Negotiation
Flow control is an X.25 optional user facility. When the x25 subscribe flow-controlcommand is used, it
permits flow control parameter negotiation of packet sizes and window sizes. This command can be altered
to one of three states: default behavior (no x25 subscribe flow-control), facilities always included, or
facilities never included (flow control parameter negotiation is not enabled). By default, these flow control
parameter negotiation facilities are included in call setup (outgoing) packets only when their values differ
from the default values.
When flow control parameter negotiation is enabled, the x25 subscribe windowsize and x25 subscribe
packetsize commands allow you to configure flow control restrictions by specifying window size and
packet size ranges for permitted and target values. A value that cannot be negotiated into the permitted
range is treated as illegal, causing the call to fail. The router first attempts values within the target range,
but allows values outside the target range to be considered as long as the range complies with procedures
defined in the ITU-T Recommendation X.25 . With this feature, the Cisco router allows different flow
control value configurations and acceptable window and packet size formats for both DTE devices.
The ability to disable flow control parameter negotiation provides compatibility with equipment that does
not support flow control parameter negotiation. Similarly, forcing flow control parameter negotiation
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Asymmetrical Flow Control
Default Flow Control Values
provides compatibility with devices that require the flow control parameter negotiation facilities to be
present in all calls.
To control packet transmission flow values on the interface, use one or more of the flow control
commands--x25 subscribe flow-control, x25 subscribe windowsize, or x25 subscribe packetsize--in
interface configuration mode.
The flow control subscription commands may be applied to an X.25 interface, to an X.25 profile, or to a
LAN interface on which the cmns enable command has been configured. For X.25 over TCP (XOT), the
flow control parameter negotiation facilities are always included (the equivalent of x25 subscribe flowcontrol always).
Default Flow Control Values
Setting correct default flow control parameters of window size and packet size is essential for correct
operation of the link because X.25 is a strongly flow controlled protocol. Mismatched default flow control
values will cause X.25 local procedure errors, evidenced by Clear and Reset events.
Note
Because X.25 requires the DTE and DCE devices to have identical default maximum packet sizes and
default window sizes, changes made to the window and packet sizes when the interface is up are held until
X.25 restarts the packet service.
Default Window Sizes
X.25 networks have a default input and output window size (the default is 2) that is defined by your
network administrator. You must set the Cisco IOS software default input and output window sizes to
match those of the network. These defaults are the values that an SVC takes on if it is set up without
explicitly negotiating its window sizes. Any PVC also uses these default values unless different values are
configured.
Default Packet Sizes
X.25 networks have a default maximum input and output packet size (the default is 128) that is defined by
your network administrator. You must set the Cisco IOS software default input and output maximum
packet sizes to match those of the network. These defaults are the values that an SVC takes on if it is set up
without explicit negotiatiation of its maximum packet sizes. Any PVC also uses these default values unless
different values are configured.
To send a packet larger than the agreed-on X.25 packet size over an X.25 VC, the Cisco IOS software must
break the packet into two or more X.25 packets with the M-bit ("more data" bit) set. The receiving device
collects all packets in the M-bit sequence and reassembles them into the original packet.
It is possible to define default packet sizes that cannot be supported by the lower layer (see the LAPB N1
parameter). However, the router will negotiate lower maximum packet sizes for all SVCs so the agreed-on
sizes can be carried. The Cisco IOS software will also refuse a PVC configuration if the resulting
maximum packet sizes cannot be supported by the lower layer.
Asymmetrical Flow Control
Asymmetrical flow control is supported by the permitted configuration of asymmetrical window and packet
sizes. For data flow from a channel with a smaller packet size than its outbound channel, the switch may
combine data packets, and for a channel with a larger packet size than its outbound channel, the switch will
fragment the packets.
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X.25 Interface Parameters
X.25 Failover
The figure below shows asymmetrical configuration of the Cisco router. DTE A (window size 3; packet
size 128) and DTE B (window size 5; packet size 256) are able to communicate despite differing window
and packet sizes.
Figure 2
Asymmetrical Window and Packet Sizes Between DTE A and DTE B
To use asymmetrical flow control effectively, use the x25 subscribe flow-control never command to
disable flow control parameter negotiation, and use the x25 routing acknowledge localcommand to enable
local acknowledgment.
X.25 Interface Parameters
Some X.25 applications have unusual or special needs. Several X.25 parameters are available to modify X.
25 behavior for these applications.
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X.25 Failover, page 17
X.25 Level 3 Timers, page 17
X.25 Addresses, page 17
Default VC Protocol, page 19
Disabling PLP Restarts, page 19
X.25 Failover
Multiple routes can be configured in an X.25 routing table to allow one or more secondary or backup
interfaces to be used when a preferred (primary) interface is not usable. Routes are examined in the order in
which they appear in the X.25 routing table, and the first matching route is taken. However, since X.25
traffic is circuit-oriented, once a connection is established via the secondary interface, the connection
remains active even after the primary interface returns to service. This situation is undesirable when the
path via the secondary interface is slower or more expensive than the path via the primary interface.
X.25 Failover enables you to configure the secondary or backup interface to reset once the primary
interface has come back up and remained operational for a specified amount of time, terminating any
connections that are still using the secondary interface. Subsequent calls will then be forwarded over the
preferred interface.
X.25 Failover supports Annex G (X.25 over Frame Relay), but it does not support XOT.
You can configure X.25 Failover on an X.25 interface or X.25 profile.
X.25 Level 3 Timers
The X.25 Level 3 event timers determine how long the Cisco IOS software waits for acknowledgment of
control packets. You can set these timers independently. Only those timers that apply to the interface are
configurable. (A DTE interface does not have the T1x timers, and a DCE interface does not have the T2x
timers.)
X.25 Addresses
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Configuring X.25 and LAPB
Interface Alias Address
When you establish SVCs, X.25 uses addresses in the form defined by ITU-T Recommendation X.121 (or
simply an "X.121 address"). An X.121 address has from zero to 15 digits. Because of the importance of
addressing to call setup, several interface addressing features are available for X.25.
The X.121 address of an X.25 interface is used when it is the source or destination of an X.25 call. The X.
25 call setup procedure identifies both the calling (source) and the called (destination) X.121 addresses.
When an interface is the source of a call, it encodes the interface X.121 address as the source address. An
interface determines that it is the destination of a received call if the destination address matches the
address of the interface.
Cisco IOS X.25 software can also route X.25 calls, which involves placing and accepting calls, but the
router is neither the source nor the destination for these calls. Routing X.25 does not modify the source or
destination addresses, thus preserving the addresses specified by the source host. Routed (switched) X.25
simply connects two logical X.25 channels to complete an X.25 VC. An X.25 VC, then, is a connection
between two hosts (the source host and the destination host) that is switched between zero or more routed
X.25 links.
The null X.121 address (the X.121 address that has zero digits) is a special case. The router acts as the
destination host for any call it receives that has the null destination address.
A subaddress is an X.121 address that matches the digits defined for the X.121 address of the interface, but
has one or more additional digits after the base address. X.25 acts as the destination host for an incoming
PAD call with a destination that is a subaddress of the address of the interface; the trailing digits specify
which line a PAD connection is requesting. This feature is described in the chapter "Configuring Protocol
Translation and Virtual Asynchronous Devices" in the Cisco IOS Terminal Services Configuration Guide .
Other calls that use a subaddress can be accepted if the trailing digit or digits are zeros; otherwise, the
router will not act as the destination host of the call.
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Interface Alias Address, page 18
Suppressing or Replacing the Calling Address, page 18
Suppressing the Called Address, page 18
Interface Alias Address
You can supply alias X.121 addresses for an interface. Supplying alias addresses allows the interface to act
as the destination host for calls having a destination address that is neither the address of the interface, an
allowed subaddress of the interface, nor the null address.
Local processing (for example, IP encapsulation) can be performed only for incoming calls whose
destination X.121 address matches the serial interface or alias of the interface.
Suppressing or Replacing the Calling Address
Some attachments require that no calling (source) address be presented in outgoing calls. This requirement
is called suppressingthe calling address . When attached to a PDN, X.25 may need to ensure that outgoing
calls use only the assigned X.121 address for the calling (source) address. Routed X.25 normally uses the
original source address. Although individual X.25 route configurations can modify the source address,
Cisco provides a simple command to force the use of the interface address in all calls sent; this requirement
is called replacing the calling address .
Suppressing the Called Address
Some attachments require that no called (destination) address be presented in outgoing calls; this
requirement is called suppressing the called address .
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X.25 Datagram Transport
Default VC Protocol
Default VC Protocol
The Call Request packet that sets up a VC can encode a field called the Call User Data (CUD) field.
Typically the first few bytes of the CUD field identify which high-level protocol is carried by the VC. The
router, when acting as a destination host, normally refuses a call if the CUD is absent or the protocol
identification is not recognized. The PAD protocol, however, specifies that unidentified calls be treated as
PAD connection requests. Other applications require that they be treated as IP encapsulation connection
requests, in accordance with RFC 877, A Standard for the Transmission of IP Datagrams over Public Data
Networks .
Disabling PLP Restarts
By default, a PLP restart is performed when the link level resets (for example, when LAPB reconnects).
Although PLP restarts can be disabled for those few networks that do not allow restarts, we do not
recommend disabling these restarts because doing so can cause anomalous packet layer behavior.
Caution
Very few networks require this feature. Cisco does not recommend that it be enabled except when you are
attaching to a network that requires it.
X.25 Datagram Transport
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Overview, page 19
Point-to-Point and Multipoint Subinterfaces, page 20
Mapping Protocol Addresses to X.121 Addresses, page 20
Mapping Datagram Addresses to X.25 Hosts, page 22
PAD Access, page 23
Encapsulation PVC, page 24
X.25 TCP IP Header Compression, page 24
X.25 Bridging, page 24
Overview
X.25 support is most commonly configured as a transport for datagrams across an X.25 network. Datagram
transport (or encapsulation) is a cooperative effort between two hosts communicating across an X.25
network. You configure datagram transport by establishing a mapping on the encapsulating interface
between the protocol address of the far host (for example, IP or DECnet) and its X.121 address. Because
the call identifies the protocol that the VC will carry (by encoding a Protocol Identifier, or PID, in the first
few bytes of the CUD field), the terminating host can accept the call if it is configured to exchange the
identified traffic with the source host.
The figure below illustrates two routers sending datagrams across an X.25 PDN.
Figure 3
Transporting LAN Protocols Across an X.25 PDN
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Configuring X.25 and LAPB
Point-to-Point and Multipoint Subinterfaces
Point-to-Point and Multipoint Subinterfaces
Subinterfaces are virtual interfaces that can be used to connect several networks to each other through a
single physical interface. Subinterfaces are made available on Cisco routers because routing protocols,
especially those using the split horizon principle, may need help to determine which hosts need a routing
update. The split horizon principle, which allows routing updates to be distributed to other routed interfaces
except the interface on which the routing update was received, works well in a LAN environment in which
other routers reached by the interface have already received the routing update.
However, in a WAN environment using connection-oriented interfaces (like X.25 and Frame Relay), other
routers reached by the same physical interface might not have received the routing update. Rather than
forcing you to connect routers by separate physical interfaces, Cisco provides subinterfaces that are treated
as separate interfaces. You can separate hosts into subinterfaces on a physical interface, X.25 is unaffected,
and routing processes recognize each subinterface as a separate source of routing updates, so all
subinterfaces are eligible to receive routing updates.
There are two types of subinterfaces: point-to-point and multipoint. Subinterfaces are implicitly multipoint
unless configured as point-to-point.
A point-to-point subinterface is used to encapsulate one or more protocols between two hosts. An X.25
point-to-point subinterface will accept only a single encapsulation command (such as the x25 map or x25
pvc command) for a given protocol, so there can be only one destination for the protocol. (However, you
can use multiple encapsulation commands, one for each protocol, or multiple protocols for one map or
PVC.) All protocol traffic routed to a point-to-point subinterface is forwarded to the one destination host
defined for the protocol. (Because only one destination is defined for the interface, the routing process need
not consult the destination address in the datagrams.)
A multipoint subinterface is used to connect one or more hosts for a given protocol. There is no restriction
on the number of encapsulation commands that can be configured on a multipoint subinterface. Because the
hosts appear on the same subinterface, they are not relying on the router to distribute routing updates
among them. When a routing process forwards a datagram to a multipoint subinterface, the X.25
encapsulation process must be able to map the destination address of the datagram to a configured
encapsulation command. If the routing process cannot find a map for the datagram destination address, the
encapsulation will fail.
Note
Because of the complex operations dependent on a subinterface and its type, the router will not allow a
subinterface’s type to be changed, nor can a subinterface with the same number be reestablished once it has
been deleted. After a subinterface has been deleted, you must reload the Cisco IOS software (by using the
reload command) to remove all internal references. However, you can easily reconstitute the deleted
subinterface by using a different subinterface number.
For more information about configuring subinterfaces, refer to the chapter "Configuring Serial Interfaces"
in the Cisco IOS Interface Configuration Guide .
When configuring IP routing over X.25, you might need to make adjustments to accommodate split horizon
effects. Refer to the chapter "Configuring RIP" in the Cisco IOS IP Configuration Guide for details about
possible split horizon conflicts. By default, split horizon is enabled for X.25 attachments.
Mapping Protocol Addresses to X.121 Addresses
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Understanding Protocol Encapsulation for Single-Protocol and Multiprotocol VCs, page 21
Understanding Protocol Identification, page 21
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Configuring X.25 and LAPB
Understanding Protocol Encapsulation for Single-Protocol and Multiprotocol VCs
Understanding Protocol Encapsulation for Single-Protocol and Multiprotocol VCs
Cisco has long supported encapsulation of a number of datagram protocols across X.25, using a standard
method when available or a proprietary method when necessary. These traditional methods assign a
protocol to each VC. If more than one protocol is carried between the router and a given host, each active
protocol will have at least one VC dedicated to carrying its datagrams.
Cisco also supports a newer standard, RFC 1356, Multiprotocol Interconnect on X.25 and ISDN in the
Packet Mode ,which standardizes a method for encapsulating most datagram protocols over X.25. It also
specifies how one VC can carry datagrams from more than one protocol.
The Cisco IOS software can be configured to use any of the available encapsulation methods with a
particular host.
After you establish an encapsulation VC using any method, the Cisco IOS software sends and receives a
datagram by simply fragmenting it into and reassembling it from an X.25 complete packet sequence. An X.
25 complete packet sequence is one or more X.25 data packets that have the M-bit set in all but the last
packet. A VC that can carry multiple protocols includes protocol identification data as well as the protocol
data at the start of each complete packet sequence.
Understanding Protocol Identification
This section contains background material only.
The various methods and protocols used in X.25 SVC encapsulation are identified in a specific field of the
call packet; this field is defined by X.25 to carry CUD. Only PVCs do not use CUD to identify their
encapsulation (because PVCs do not use the X.25 call setup procedures).
The primary difference between the available Cisco and IETF encapsulation methods is the specific value
used to identify a protocol. When any of the methods establishes a VC for carrying a single protocol, the
protocol is identified in the call packet by the CUD.
The table below summarizes the values used in the CUD field to identify protocols.
Table 2
Protocol Identification in the CUD Field
Protocol
Cisco Protocol Identifier
IETF RFC 1356 Protocol Identifier
Apollo Domain
0xD4
0x80 (5-byte SNAP encoding)1
AppleTalk
0xD2
0x80 (5-byte SNAP encoding)
Banyan VINES
0xC0 00 80 C42
0x80 (5-byte SNAP encoding)
Bridging
0xD5
Not implemented
ISO CLNS
0x81
0x813
Compressed TCP
0xD8
0x00 (multiprotocol)4
1 SNAP encoding is defined according to the Assigned Numbers RFC; the Cisco implementation recognizes only the IETF organizational unique identifier
(OUI) 0x00 00 00 followed by a 2-byte Ethernet protocol type.
2 The use of 0xC0 00 80 C4 for Banyan VINES is defined by Banyan.
3 The use of 0x81 for CLNS is compatible with ISO/IEC 8473-3:1994.
4 Compressed TCP traffic has two types of datagrams, so IETF encapsulation requires a multiprotocol VC.
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Configuring X.25 and LAPB
Mapping Datagram Addresses to X.25 Hosts
Protocol
Cisco Protocol Identifier
IETF RFC 1356 Protocol Identifier
DECnet
0xD0
0x80 (5-byte SNAP encoding)
IP
0xCC
0xCC5
or
0x80 (5-byte SNAP encoding)
Novell IPX
0xD3
0x80 (5-byte SNAP encoding)
PAD
0x01 00 00 006
0x01 00 00 006
QLLC
0xC3
Not available
XNS
0xD1
0x80 (5-byte SNAP encoding)
Multiprotocol
Not available
0x00
Once a multiprotocol VC has been established, datagrams on the VC have protocol identification data
before the actual protocol data; the protocol identification values are the same as those used by RFC 1356
in the CUD field for an individual protocol.
Note
IP datagrams can be identified with a 1-byte identification (0xCC) or a 6-byte identification (0x80 followed
by the 5-byte SNAP encoding). The 1-byte encoding is used by default, although the SNAP encoding can
be configured.
Mapping Datagram Addresses to X.25 Hosts
Encapsulation is a cooperative process between the router and another X.25 host. Because X.25 hosts are
reached with an X.121 address (an X.121 address has 0 to 15 decimal digits), the router must have a means
to map protocols and addresses of the host to its X.121 address.
Each encapsulating X.25 interface must be configured with the relevant datagram parameters. For example,
an interface that encapsulates IP typically will have an IP address.
A router set up for DDN or BFE service uses a dynamic mapping technique to convert between IP and X.
121 addresses. These techniques have been designed specifically for attachment to the DDN network and to
Blacker encryption equipment. Their design, restrictions, and operation make them work well for these
specific applications, but not for other networks.
You must also establish the X.121 address of an encapsulating X.25 interface using the x25 address
interface configuration command. This X.121 address is the address to which encapsulation calls are
directed, and is also the source X.121 address used for originating an encapsulation call. It is used by the
destination host to map the source host and protocol to the protocol address. An encapsulation VC must be
a mapped at both the source and destination host interfaces. A DDN or BFE interface will have an X.121
address generated from the interface IP address, which, for proper operation, should not be modified.
For each X.25 interface, you must explicitly map the protocols and addresses for each destination host to its
X.121 address. If needed and the destination host has the capability, one host map can be configured to
support several protocols; alternatively, you can define one map for each supported protocol.
5 The use of 0xCC for IP is backward-compatible with RFC 877, IP encapsulation [RFC:08] RFC 877.
6 The use of 0x01 00 00 00 for PAD is defined by ITU-T Recommendation X.29 .
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Configuring X.25 and LAPB
PAD Access
To establish an X.25 map, use the x25 map command in interface configuration mode.
For example, if you are encapsulating IP over a given X.25 interface, you must define an IP address for the
interface and, for each of the desired destination hosts, map the IP address of the host to its X.121 address.
Note
You can map an X.121 address to as many as nine protocol addresses, but each protocol can be mapped
only once in the command line.
An individual host map can use keywords to specify the following protocols:
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apollo --Apollo Domain
appletalk --AppleTalk
bridge --Bridging
clns --OSI Connectionless Network Service
compressedtcp --TCP/IP header compression
decnet --DECnet
ip --IP
ipx --Novell IPX
pad --Packet assembler/disassembler
qllc --IBM QLLC
vines --Banyan VINES
xns --XNS
Each mapped protocol, except bridging and CLNS, takes a datagram address. All bridged datagrams are
either broadcast to all bridging destinations or sent to the X.121 address of a specific destination host, and
CLNS uses the mapped X.121 address as the subnetwork point of attachment (SNPA), which is referenced
by a clns neighbor command. The configured datagram protocols and their relevant addresses are mapped
to the X.121 address of the destination host. All protocols that are supported for RFC 1356 operation can be
specified in a single map. (Bridging and QLLC are not supported for RFC 1356 encapsulation.) If IP and
TCP/IP header compression are both specified, the same IP address must be given for both protocols.
When setting up the address map, you can include options such as enabling broadcasts, specifying the
number of VCs allowed and defining various user facility settings.
Note
Multiprotocol maps, especially those configured to carry broadcast traffic, can result in significantly larger
traffic loads, requiring a larger hold queue, larger window sizes, or multiple VCs.
For specific information about how to establish a protocol to run over X.25, refer to the appropriate
protocol chapters in the Cisco IOS IP Configuration Guide , Cisco IOS AppleTalk and Novell IPX
Configuration Guide , and Cisco IOS Apollo Domain, Banyan VINES, DECnet, ISO CLNS, and XNS
Configuration Guide .
You can simplify the configuration for the Open Shortest Path First (OSPF) protocol by adding the optional
broadcast keyword. See the x25 map command description in the Cisco IOS Wide-Area Networking
Command Reference for more information.
PAD Access
By default, PAD connection attempts are processed for session creation or protocol translation (subject to
the configuration of those functions) from all hosts. You can configure outgoing PAD access using the
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Additional X.25 Datagram Transport Features
Encapsulation PVC
optional features of the x25 map pad command without restricting incoming PAD connections to the
configured hosts.
Encapsulation PVC
PVCs are the X.25 equivalent of leased lines; they are never disconnected. You need not configure an
address map before defining a PVC; an encapsulation PVC implicitly defines a map.
To establish a PVC, use the x25 pvc command. The x25 pvccommand uses the same protocol keywords as
the x25 map command. See the section "Mapping Datagram Addresses to X.25 Hosts, page 22" earlier in
this chapter for a list of protocol keywords. Encapsulation PVCs also use a subset of the options defined for
the x25 map command.
The user may establish multiple, parallel PVCs that carry the same set of encapsulation traffic by
specifying the identical mappings for each PVC. Additionally, the user can permit a mixture of SVCs and
PVCs to carry the traffic set by using the x25 map command to specify an nvc count that exceeds the
number of configured PVCs. The total number of VCs, of whatever type, can never exceed 8.
X.25 TCP IP Header Compression
Cisco supports RFC 1144 TCP/IP header compression (THC) on serial lines using HDLC and X.25
encapsulation. THC encapsulation is only slightly different from other encapsulation traffic, but the
differences are worth noting. The implementation of compressed TCP over X.25 uses one VC to pass the
compressed packets. Any IP traffic (including standard TCP) is separate from THC traffic; it is carried over
separate IP encapsulation VCs or identified separately in a multiprotocol VC.
Note
If you specify both ip and compressedtcp in the same x25 map compressedtcp command, they must both
specify the same IP address.
X.25 Bridging
Cisco IOS transparent bridging software supports bridging over X.25 VCs. Bridging is not supported for
RFC 1356 operation. Bridge maps must include the broadcast option for correct operation.
Additional X.25 Datagram Transport Features
The Cisco IOS software allows you to configure additional X.25 datagram transport features, including
various user facilities defined for X.25 call setup by using the options in the x25 map or x25 pvc
encapsulation command (or by setting an interface default).
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X.25 Payload Compression, page 24
Establishing the Packet Acknowledgment Policy, page 25
X.25 User Facilities, page 25
X.25 Payload Compression
For increased efficiency on relatively slow networks, the Cisco IOS software supports X.25 payload
compression of outgoing encapsulation traffic.
The following restrictions apply to X.25 payload compression:
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Configuring X.25 and LAPB
Establishing the Packet Acknowledgment Policy
•
The compressed VC must connect two Cisco routers, because X.25 payload compression is not
standardized.
The data packets conform to X.25 rules, so a compressed VC can be switched through standard X.25
equipment. However, only Cisco routers can compress and decompress the data.
•
Only datagram traffic can be compressed, although all the encapsulation methods supported by Cisco
routers are available (for example, an IETF multiprotocol VC can be compressed).
SVCs cannot be translated between compressed and uncompressed data, nor can PAD data be compressed.
•
X.25 payload compression must be applied carefully.
Each compressed VC requires significant memory resources (for a dictionary of learned data patterns) and
computation resources (every data packet received is decompressed and every data packet sent is
compressed). Excessive use of compression can cause unacceptable overall performance.
•
X.25 compression must be explicitly configured for a map command.
A received call that specifies compression will be rejected if the corresponding host map does not specify
the compressoption. An incoming call that does not specify compression can, however, be accepted by a
map that specifies compression.
To enable payload compression over X.25, use the x25 map command. This command specifies that X.25
compression is to be used between the two hosts. Because each VC established for compressed traffic uses
significant amounts of memory, compression should be used with careful consideration of its impact on the
performance. The compress keyword may be specified for an encapsulation PVC.
Establishing the Packet Acknowledgment Policy
You can instruct the Cisco IOS software to send an acknowledgment packet when it has received a
threshold of data packets it has not acknowledged, instead of waiting until its input window is full. A value
of 1 sends an acknowledgment for each data packet received if it cannot be acknowledged in an outgoing
data packet. This approach improves line responsiveness at the expense of bandwidth. A value of 0 restores
the default behavior of waiting until the input window is full.
X.25 User Facilities
X.25 software provides commands to support X.25 user facilities options (specified by the ITU-T
Recommendation X.25 ) that allow you to use network features such as reverse charging, user
identification, and flow control negotiation. You can choose to configure facilities on a per-map basis or on
a per-interface basis. In the following table, the x25 map commands configure facilities on a per-map
basis; the x25 facility commands specify the values set for all encapsulation calls originated by the
interface. Routed calls are not affected by the facilities specified for the outgoing interface.
The packetsize and windowsize and options are supported for PVCs, although the options have a slightly
different meaning on PVCs from what they they mean on interfaces because PVCs do not use the call setup
procedure. If the PVC does not use the interface defaults for the flow control parameters, these options
must be used to specify the values. Not all networks will allow a PVC to be defined with arbitrary flow
control values.
Additionally, the D-bit is supported, if negotiated. PVCs allow the D-bit procedure because there is no call
setup to negotiate its use. Both restricted and unrestricted fast select are also supported and are
transparently handled by the software. No configuration is required for use of the D-bit or fast select
facilities.
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X.25 Routing
X.25 Route
X.25 Routing
The X.25 software implementation allows VCs to be routed from one X.25 interface to another and from
one router to another. The routing behavior can be controlled with switching and XOT configuration
commands, based on a locally built table.
X.25 encapsulation can share an X.25 serial interface with the X.25 switching support. Switching or
forwarding of X.25 VCs can be done two ways:
•
•
Incoming calls received from a local serial interface running X.25 can be forwarded to another local
serial interface running X.25. This method is known as local X.25 switching because the router handles
the complete path. It does not matter whether the interfaces are configured as DTE or DCE devices,
because the software takes the appropriate actions.
An incoming call can also be forwarded using the XOT service (previously remote switching or
tunneling). Upon receipt of an incoming X.25 call, a TCP connection is established to the destination
XOT host (for example, another Cisco router) that will, in turn, handle the call using its own criteria.
All X.25 packets are sent and received over the reliable TCP data stream. Flow control is maintained
end-to-end. It does not matter whether the interface is configured for DTE or DCE devices, because
the software takes the appropriate actions.
Running X.25 over TCP/IP provides a number of benefits. The datagram containing the X.25 packet can be
switched by other routers using their high-speed switching abilities. X.25 connections can be sent over
networks running only the TCP/IP protocols. The TCP/IP protocol suite runs over many different
networking technologies, including Ethernet, Token Ring, T1 serial, and FDDI. Thus X.25 data can be
forwarded over these media to another router, where it can, for example, be switched to an X.25 interface.
When the connection is made locally, the switching configuration is used; when the connection is across a
LAN, the XOT configuration is used. The basic function is the same for both types of connections, but
different configuration commands are required for each type of connection.
The X.25 switching subsystem supports the following facilities and parameters:
•
•
•
D-bit negotiation (data packets with the D-bit set are passed through transparently)
Variable-length interrupt data (if not operating as a DDN or BFE interface)
Flow control parameter negotiation:
•
•
•
◦ Window size up to 7, or 127 for modulo 128 operation
◦ Packet size up to 4096 (if the LAPB layers used are capable of handling the requested size)
Basic CUG selection
Throughput class negotiation
Reverse charging and fast select
The handing of these facilities is described in the appendix "X.25 Facility Handling."
•
X.25 Route, page 26
X.25 Route
An X.25 route table enables you to control which destination is selected for several applications. When an
X.25 service receives a call that must be forwarded, the X.25 route table determines which X.25 service (X.
25, CMNS, or XOT) and destination should be used. When a PAD call is originated by the router, either
from a user request or from a protocol translation event, the route table similarly determines which X.25
service and destination should be used.
You create the X.25 route table and add route entries to it. You can optionally specify the order of the
entries in the table, the criteria to match against the VC information, and whether to modify the destination
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Additional X.25 Routing Features
X.25 Load Balancing
or source addresses. Each entry must specify the disposition of the VC (that is, what is done with the VC).
Each route can also specify XOT keepalive options.
The route table is used as follows:
•
•
•
•
VC information is matched against selection criteria specified for each route.
The table is scanned sequentially from the top.
The first matching route determines how the VC is handled.
Once a matching entry is found, the call addresses can be modified and the call disposed of (forwarded
or cleared) as instructed by the entry.
Each application can define special conditions if a route will not be used or what occurs if no route
matches. For instance, switched X.25 will skip a route if the disposition interface is down and clear a call if
no route matches. X.25 PAD and PAD-related applications, such as protocol translation using X.25, will
route the call to the default X.25 interface, which is the first X.25 interface configured.
To configure an X.25 route (thus adding the route to the X.25 routing table), use the x25 route command.
Additional X.25 Routing Features
•
•
•
X.25 Load Balancing, page 27
XOT to Use Interface Default Flow Control Values, page 28
Calling Address Interface-Based Insertion and Removal, page 28
X.25 Load Balancing
X.25 load balancing was created to solve the problem that arises when the number of users accessing the
same host causes an overload on Internet service provider (ISP) application resources.
In the past, in order to increase the number of users they could support, ISPs had to increase the number of
X.25 lines to the host. To support a large number of VCs to a particular destination, they had to configure
more than one serial interface to that destination. When a serial interface is configured to support X.25, a
fixed number of VCs is available for use. However, the X.25 allocation method for VCs across multiple
serial lines filled one serial line to its VC capacity before utilizing the second line at all. As a result, the first
serial line was frequently carrying its maximum data traffic before it ran out of VCs.
Using a facility called hunt groups, the X.25 Load Balancing feature causes a switch to view a pool of X.25
lines going to the same host as one address and assign VCs on an idle logical channel basis. With this
feature, X.25 calls can be load-balanced among all configured outgoing interfaces to fully use and balance
performance of all managed lines. X.25 load balancing allows two load-balancing distribution methods-rotary and vc-count--utilizing multiple serial lines.
The rotary method sends every call to the next available interface, regardless of line speed and the number
of available VCs on that interface.
The vc-count method sends calls to the interface that has the largest number of available logical channels.
This method ensures a good load balance when lines are of equal speed. If the line speeds are unequal, the
vc-count method will favor the line with the higher speed. To distribute calls equally among interfaces
regardless of line speed, configure each interface with the same number of VCs. In cases where interfaces
have the same line speed, the call is sent to the interface that is defined earliest in the hunt group.
With the vc-count distribution method, if a hunt group does not contain an operational interface, the call is
forwared to the next route if one has been specified. An interface is considered unoperational if that
interface is down or full. If a session is terminated on an interface within the hunt group, that interface now
has more available VCs, and it will be chosen next.
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DNS-Based X.25 Routing
XOT to Use Interface Default Flow Control Values
Note
XOT cannot be used in hunt groups configured with the vc-count distribution method. XOT does not limit
the number of calls that can be sent to a particular destination, so the method of selecting the hunt group
member with the largest number of available VCs will not work. XOT can be used in hunt groups
configured with the rotary distribution method.
Only one distribution method can be selected for each hunt group, although one interface can participate in
one or more hunt groups. Reconfiguration of hunt groups does not affect functionality, but distribution
methods are limited to rotary and vc-count only.
XOT to Use Interface Default Flow Control Values
When a connection is set up, the source and destination XOT implementations must cooperate to determine
the flow control values that apply to the SVC. The source XOT ensures cooperation by encoding the X.25
flow control facilities (the window sizes and maximum packet sizes) in the X.25 Call packet; the XOT
implementation of the far host can then correctly negotiate the flow control values at the destination
interface and, if needed, indicate the final values in the X.25 Call Confirm packet.
When XOT receives a call that leaves one or both flow control values unspecified, it supplies the values.
The values supplied are a window size of 2 packets and maximum packet size of 128 bytes; according to
the standards, any SVC can be negotiated to use these values. Thus when XOT receives a call from an older
XOT implementation, it can specify in the Call Confirm packet that these flow control values must revert to
the lowest common denominator.
The older XOT implementations required that the source and destination XOT router use the same default
flow control values on the two X.25 interfaces that connect the SVC. Consequently, connections with
mismatched flow control values were created when this assumption was not true, which resulted in
mysterious problems. In the Cisco IOS Release 12.2 XOT implementation, the practice of signalling the
values used in the Call Confirm packet avoids these problems.
Occasionally the older XOT implementation will be connected to a piece of X.25 equipment that cannot
handle modification of the flow control parameters in the Call Confirm packet. These configurations should
be upgraded to use a more recent version of XOT; when upgrade is not possible, the behavior of XOT
causes a migration problem. In this situation, you may configure the Cisco IOS software to cause XOT to
obtain unspecified flow control facility values from the default values of the destination interface.
Calling Address Interface-Based Insertion and Removal
This feature describes a modification to the x25 route command that allows interface-based insertion and
removal of the X.121 address in the X.25 routing table.
This capability allows Cisco routers running X.25 to conform to the standard that specifies that X.25 DCE
devices should not provide the X.25 calling address, but instead that it should be inserted by the X.25 DTE
based on interface. This calling address insertion and removal feature was designed for all routers
performing X.25 switching and requiring that an X.121 address be inserted or removed by the X.25 DTE
based on the interface.
This feature does not support XOT to X.25 routing using the input-interface keyword introduced by the
Calling Address Insertion and Removal feature.
DNS-Based X.25 Routing
•
Overview, page 29
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Configuring X.25 and LAPB
Overview
•
•
Address Resolution, page 30
Mnemonic Resolution, page 31
Overview
Managing a large TCP/IP network requires accurate and up-to-date maintenance of IP addresses and X.121
address mapping information on each router database in the network. Because these IP addresses are
constantly being added and removed in the network, the routing table of every router needs to be updated,
which is a time consuming and error-prone task. This process has also been a problem for mnemonics (an
easy-to-remember alias name for an X.121 address).
X.25 has long operated over an IP network using XOT. However, large networks and financial legacy
environments experienced problems with the amount of route configuration that needed to be done
manually, as each router switching calls over TCP needed every destination configured. Every destination
from the host router needed a static IP route statement, and for larger environments, these destinations
could be as many as several thousand per router. Until the release of Domain Name System (DNS)-based
X.25 routing, the only way to map X.121 addresses and IP addresses was on a one-to-one basis using the
x25 route x121address xot ipaddress command.
The solution was to centralize route configurations that routers could then access for their connectivity
needs. This centralization is the function of DNS-based X.25 routing, because the DNS server is a database
of all domains and addresses on a network.
DNS-based X.25 routing scales well with networks that have multiple XOT routers, simplifies maintenance
of routing table and creation of new routes, and reduces labor-intensive tasks and the possibility of human
error during routing table maintainance. You must have DNS activated and X.25 configured for XOT to
enable DNS-based X.25 routing.
DNS has the following three components:
•
•
•
Domain name space or resource records--Define the specifications for a tree-structured domain name
space.
Name servers--Hold information about the domain tree structure.
Resolvers--Receive a client request and return the desired information in a form compatible with a
local hosts data formats.
You need to maintain only one route statement in the host router to connect it to the DNS. When DNS is
used, the following rules apply:
•
•
•
•
•
•
•
•
•
You must use Cisco IOS name server configuration commands.
X.28 mnemonic restrictions apply (for example, not using -, ., P, or D in the mnemonic).
You cannot specify any x25 route command options on the DNS. These options must be configured
within the x25 route command itself.
Names must consist of printable characters.
No embedded white space is permitted.
Periods must separate subdomains.
Names are case sensitive.
You must append any domain configured for the router to the user-specified name format.
The total length of the name must not exceed 255 characters.
For more information on configuring the DNS, see the chapter "Configuring the DNS Service" in the Cisco
DNS/DHCP Manager Administrator’s Guide.
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Configuring X.25 and LAPB
Address Resolution
Note
This feature should not be used in the public Internet. It should be used only for private network
implementations because in the Internet world the DNS has conventions for names and addresses with
which DNS-based X.25 routing does not comply.
Address Resolution
With DNS-based X.25 routing, managing the X.121-to-IP addressing correlation and the mnemonic-to-X.
121 addressing correlation is easy. Instead of supplying the router multiple route statements to all
destinations, it may be enough to use a single wildcard route statement that covers all addresses in the
DNS.
The x25 route disposition xot command option has been modified to include the dns patternargument after
the xot keyword, where pattern is a rewrite element that works in the same way that address substitution
utilities work (see the Cisco IOS Wide-Area Networking Command Reference for further details).
The wildcard ^.* characters and \0 pattern of the modified x25 route ^.* xot dns \0 command give the
command more universality and effectiveness and make DNS-based X.25 routing simple and easy to use.
These characters and pattern already exist and are explained in detail under the x25 route command in the
Cisco IOS Wide-Area Networking Command Reference . This command functions only if the DNS route
table mapping has been configured in a method recognized and understood by X.25 and the DNS server.
The following example is a setup from a DNS route table showing which X.121 address relates to which IP
address:
222 IN
444 IN
555 IN
A
A
A
172.18.79.60
10.1.1.3
10.1.1.2 10.1.2.2 10.1.3.2 10.1.4.2 10.1.5.7 10.1.6.3
The command line x25 route 444 xot dns \0shown in the DNS-based X.25 routing configuration example
is what extracts the IP address from the DNS. The \0 pattern replaces itself with 444. The 444 is then used
as the index into the DNS route table to generate the IP address 10.1.1.3. Other characters can be combined
with the pattern; for example, A-\0. In the DNS database, the index would appear as A-444.
As the example in the figure below shows, a call sent by the router goes to the DNS. The DNS checks its
route table and identifies the X.121 address 444 and its related IP address 10.1.1.3. The DNS returns the IP
address to the host router, which then creates a route statement and forwards the data to the IP address of
the destination router (10.1.1.3).
If the DNS-based X.25 routing configuration example included the command x25 route 555 xot dns \0,
then a call to the X.121 address 555 would also go to the DNS. Since multiple IP addresses have been
configured in the domain name space records, all of the IP addresses for that domain name would be
returned to the router. Each address would be tried in sequence, just as if the X.25 routing configuration
had been x25 route 555 xot 10.1.1.2 10.1.2.2 10.1.3.2 10.1.4.2 10.1.5.7 10.1.6.3. The router will accept up
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Configuring X.25 and LAPB
Mnemonic Resolution
to 6 IP addresses from DNS for the domain name. If there are more than six, there will be an error message,
and the list will be trucated to the first six received.
Figure 4
DNS-Based X.25 Routing Using XOT over an IP Cloud
Mnemonic Resolution
DNS-based X.25 routing can be used for mnemonic resolution with or without use of XOT routing. For
more information on mnemonic addressing, refer to the chapter "Configuring the Cisco PAD Facility for X.
25 Connections" chapter in the Cisco IOS Terminal Services Configuration Guide.
When mnemonics are used with XOT, the same communication with the DNS occurs, except that the
router needs to contact the DNS twice--first to get the X.121 address using the mnemonic, and then to get
the IP address using the X.121 address. However, there is no substantial performance issue because the
process happens very quickly.
The following example is a setup from the DNS route table showing a mnemonic and its related X.121
address ("destination_host" represents 222). The X25 keyword ensures that this line will be recognized by
DNS-based X.25 routing in the DNS server.
destination_host IN
X25
222
Using X.28 to retrieve this address, you would enter the following commands:
Router# x28
*destination_host
Translating "destination_host"...domain server (10.1.1.40)
Notice the output line requesting mnemonic resolution from the DNS server with IP address 10.1.1.40.
If you were using PAD, you would need to enter only the mnemonic name, as in the following example:
Router# pad destination_host
Caution
You must remove any permanent entry for X.25 located in the host table of the router that has been
duplicated in the DNS route table (as part of the enabling process for DNS-based X.25 routing). Otherwise,
DNS-based X.25 routing will be overridden by the host table entries of the router.
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X.25 over Frame Relay (Annex G)
Mnemonic Resolution
To configure DNS-based X.25 routing, use the following command in global configuration mode. This task
assumes that you already have XOT and DNS configured and enabled and that the route table in the DNS
server has been correctly organized.
X.25 over Frame Relay (Annex G)
Annex G (X.25 over Frame Relay) facilitates the migration of traffic from an X.25 backbone to a Frame
Relay backbone by permitting encapsulation of X.25 traffic within a Frame Relay connection. With Annex
G, transporting X.25 over Frame Relay has been simplified by allowing direct and transparent X.25
encapsulation over a Frame Relay network. Annex G is supported only on Frame Relay main interfaces
(not subinterfaces) and over Frame Relay PVCs. However, X.25 PVC connections are not supported, but
only X.25 SVC connections.
X.25 profiles make Annex G easy to configure for both X.25 and LAPB because they consist of bundled X.
25 and LAPB commands. Once created and named, X.25 profiles can be simultaneously associated with
more than one DLCI connection, using just the profile name. This process means that you need not enter
the same X.25 or LAPB commands for each DLCI you are configuring. Multiple Annex G DLCIs can use
the same X.25 profile, but the DLCIs can be configured for only one Frame Relay service at a time. The
creation of X.25 profiles allows the specification of X.25 and LAPB configurations without the need to
allocate hardware interface data block (IDB) information. X.25 profiles do not support IP encapsulation.
Annex G provides multiple logical X.25 SVCs per Annex G link, and modulo 8 and 128 are supported. X.
25 Layers 2 and 3 are transparently supported over Annex G. LAPB treats the Frame Relay network like an
X.25 network link and passes all of the data and control messages over the Frame Relay network. Before
enabling Annex G connections you must establish a Frame Relay connection.
CMNS Routing
CMNS provides a mechanism through which X.25 services can be extended to nonserial media through the
use of packet-level X.25 over frame-level logical link control (LLC2). For information about configuring
LLC2 parameters, refer to the chapter "Configuring SDLC and LLC2 Parameters" in the Cisco IOS
Bridging and IBM Networking Configuration Guide .
The Cisco CMNS implementation permits most X.25 services to be extended across a LAN, although
datagram encapsulation and QLLC operations are not available. For example, a DTE host and a Sun
workstation can be interconnected via the router’s LAN interfaces and to a remote OSI-based DTE through
a WAN interface to an X.25 packet-switched network (PSN).
Priority Queueing or Custom Queueing for X.25
Two types of output queueing are available for X.25:
•
•
Priority queueing--Classifies packets on the basis of certain criteria and then assigns the packets to one
of four output queues, with high, medium, normal, or low priority.
Custom queueing--Classifies packets, assigns them to one of 16 output queues, and controls the
percentage of available bandwidth for an interface that is used for a queue.
Output queueing for X.25 interfaces differs subtly from its use with other protocols because X.25 is a
strongly flow-controlled protocol. Each X.25 VC has an authorized number of packets it can send before it
must suspend transmission to await acknowledgment of one or more of the packets that were sent.
Queue processing is also subject to a VC’s ability to send data; a high priority packet on a VC that cannot
send data will not stop other packets from being sent if they are queued for a VC that can send data. In
addition, a datagram that is being fragmented and sent may have its priority artificially promoted if higherpriority traffic is blocked by the fragmentation operation.
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X.25 Closed User Groups
Closed User Group
Both priority queueing and custom queueing can be defined, but only one method can be active on a given
interface.
Note
Connection-oriented VCs (for example, QLLC, PAD, and switched X.25) will use the default queue of the
interface. To maintain the correct order, all connection-oriented VCs use a single output queue for sending
data.
X.25 Closed User Groups
•
•
•
•
•
•
•
•
•
•
Closed User Group, page 33
Understanding CUG Configuration, page 35
Point of Presence, page 36
CUG Membership Selection, page 36
CUG Service Access and Properties, page 37
POP with No CUG Access, page 37
POP with Access Restricted to One CUG, page 38
POP with Multiple CUGs and No Public Access, page 38
POP with Multiple CUGs and Public Access, page 38
CUG Selection Facility Suppression, page 38
Closed User Group
A closed user group (CUG) is a collection of DTE devices for which the network controls access between
two members and between a member and a nonmember. An X.25 network can support up to 10,000 CUGs
(numbered from 0 to 9999), each of which can have any number of member DTE devices. An individual
DTE becomes a member of a specific network CUG by subscription. The subscription data includes the
local number the DTE will use to identify the network CUG (which may or may not be the same as the
network number, as determined by network administration and the requirements of the DTE device), and
any restriction that prohibits the DTE from placing a call within the CUG or, conversely, prohibits the
network from presenting a call within the CUG to the DTE device.
The X.25 DCE interfaces of the router can be configured to perform the standard CUG access controls
normally associated with a direct attachment to an X.25 network POP. The DCE interface of the router acts
as the boundary between the DTE and the network, and CUG use ensures that only those incoming and
outgoing SVCs consistent with the configured CUG subscriptions are permitted. X.25 CUG configuration
commands on the router are specified at every POP, and CUG security decisions are made solely from
those commands. However, CUG service is not supported on XOT connections.
CUG security depends on CUG decisions made by the two POPs used to connect an SVC through the
network, so CUG security depends on the collective configuration of all POPs that define the network
boundary. The standalone interface configuration determines if the POP will permit user access for a given
incoming or outgoing call within the authorized CUG.
CUGs are a network service designed to allow various network subscribers (DTE devices) to be segregated
into private subnetworks with limited incoming or outgoing access. This means that a DTE must obtain
membership from its network service (POP) for the set of CUGs it needs access to. A DTE may subscribe
to zero, one, or several CUGs at the same time. A DTE that does not require CUG membership for access is
considered to be in the open part of the network. Each CUG typically permits subscribing users to connect
to each other, but precludes connections with nonsubscribing DTE devices.
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Configuring X.25 and LAPB
Closed User Group
However, CUG behavior is highly configurable. For instance, a CUG configuration may subscribe a DTE
to a given CUG, but bar it from originating calls within the CUG or, conversely, bar it from receiving calls
identified as being within the CUG. CUG configuration can also selectively permit the DTE to originate
calls to a DTE on the open network, or permit the DTE to receive calls from a DTE on the open network.
CUG access control is first applied when the originating DTE places a call to the POP, and again when the
POP of the destination DTE device receives the call for presentation. Changes to the POP CUG
subscriptions will not affect any SVCs that have already been established.
When a DTE belongs to more than one CUG, it must specify its preferential CUG, unless a call is
specifically aimed at devices outside the CUG network. However, the number of CUGs to which a DTE
can belong depends on the size of the network. Unsubscribing from one CUG or the overall CUG service
will not result in the termination of the SVC connections.
CUG behavior is a cooperative process between two network devices. The DCE offers this service to the
connecting subscribers via the DTE device. There is no global database regarding CUG membership;
therefore, the Cisco router uses information configured for the various X.25 devices and the encoded CUG
information in the outgoing and incoming packets.
X.25 CUGs are used for additional X.25 access protection and security. In a setup where DTE devices are
attached to a PDN, you can derive a private subnetwork by subscribing your DTE devices to a set of CUGs,
which allows closer control of your DTE devices, such as permitting or restricting which DTE can talk to
other DTE devices and for what particular purpose. For example, a distinct CUG can be defined to handle
each of the different modes of connectivity, such as the following:
•
•
•
•
Datagram encapsulation operation among all company sites
PAD services for customers seeking public information
PAD services for system administration internal access to consoles
QLLC access restricted to the company financial centers
One site could have different CUG subscriptions, depending on connectivity requirements. These sites
could all have restrictions regarding which other company devices can be reached (within a CUG), whether
a device is permitted to call the open network for a given function, and whether a public terminal can
access the device for a given function.
By default, no CUG behavior is implemented. Therefore, in order to observe CUG restrictions, all users
attached to the network must be subscribed to CUG behavior (CUG membership) even if they are not
subscribed to a specific CUG.
The figure below shows two CUGs (CUG 1 and CUG 2). DTE devices A, B, and C are members of CUG
1. They can initiate and receive calls only from the other members of CUG 1. They are therefore members
of a private subnet with no access to other DTE devices. DTE A is also a member of CUG 2 with DTE D,
but DTE D cannot send calls to or receive calls from DTE B or DTE C. The router checks each received
call to determine if it is intended for their CUG. If not, the router rejects the call.
You can subscribe to multiple CUGs per interface, but each CUG that is permitted must be specifically
configured. All CUGs are sorted by their local identifier. The main limitation to the number of CUGs
configured is the amount of nonvolatile memory to store the configuration. Having subscribed to a CUG,
the DTE indicates which CUG is being called. If the DTE does not indicate a CUG, its DCE determines
which CUG is used and if the call should be allowed.
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Configuring X.25 and LAPB
Understanding CUG Configuration
Note
CUG service is implemented at the DCE interface, which means that it specifies a network function. For a
summary of DCE operations, refer to ITU-T 1996 Recommendation X.301 tables 7-6 and 7-8.
Figure 5
DTE Devices A, B, C, and D Connecting to CUGs 1 and 2 over a PDN
Understanding CUG Configuration
Answering the following questions will help you set up your CUG service and CUGs:
•
Do you want to permit incoming public access to the DTE device?
If so, configure the x25 subscribe cug-service incoming-accesscommand on the DCE so that the CUG
service from the open network allows incoming calls to the DTE device.
•
Do you want to permit outgoing public access for the DTE device?
If so, configure the x25 subscribe cug-service outgoing-access command on the DCE so that the CUG
service allows public outgoing calls from the DTE to the open network.
•
Will the CUG users require restricted access to the PDN?
If so, configure the x25 subscribe local-cugcommand for mapping the local CUG to the network CUG for
the same CUG entity. To obtain full access to the PDN, the CUG service will need to be subscribed to by
both incoming and outgoing access.
If you want a secure CUG with no access to the PDN, subscribe the CUG to no incoming or outgoing
access, and configure it to communicate only with other attachments within CUGs that it has defined.
After establishing that you want PDN CUG access, you must then answer the following questions:
•
◦
Can the user place calls within the CUG?
The default is set for users to be able to place calls. If you do not want this setting, use the no-outgoing
keyword.
•
◦
Can the user receive calls within the CUG?
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Configuring X.25 and LAPB
Point of Presence
The default is set for users to be able to receive calls. If you do not want this setting, use the no-incoming
keyword.
•
◦
Do you want a subscribed CUG to be assumed when a CUG member places a call without
specifying a CUG?
If so, use the preferential keyword.
Point of Presence
X.25 is not a POP by default, and POP behavior does not automatically enforce CUG security. Within
PDNs, all devices are connected by POPs, which are open entry points into a network and, as such, pose a
potential security risk.
When you enable X.25 CUG service, you are configuring your network like a PDN, and so for every POP
with attachments in the network you must configure CUG security. CUG security is particularly important
on those POPs that do not subscribe to CUGs, because they could act as a "back door" into your CUGs.
Note
If you do not configure CUG security on your network POPs, you are creating a security risk for your
network. Configuration must be done manually for every POP in your network.
CUG Membership Selection
CUG membership selection occurs from the calling DTE in an outgoing (call request) packet to specify the
CUG membership selected for the call. CUG membership selection is requested or received by a DTE only
after the DTE has subscribed to one or more of the following facilities:
•
•
•
Relevant CUG service
Outgoing access CUG, which allows the source DTE to identify the CUG within which it is placing
the call
Incoming access CUG, which allows the destination DTE to identify the CUG to which both DTE
devices belong
Preferential CUGs
A DTE that subscribes to more than one CUG (and permits neither incoming nor outgoing access from or
to the open network) must designate a preferential CUG. Its use is assumed when no CUG selection is
enabled in the outgoing call (call request) or incoming call. Using a preferential CUG achieves a higher
level of security. Preferential CUG designation is for DTE devices meant to operate without requiring a
CUG selection facility in every outgoing call, or for DTE devices not capable of encoding a CUG selection.
Preferential CUG designation options are as follows:
•
•
•
•
If no preferential CUG has been designated and a CUG member presents a call without specifying a
receiving CUG, the call will be rejected, unless incoming access from the open network is configured.
If a preferential CUG has been designated and the user presents a call without specifying a CUG, the
call will be directed to the preferential CUG.
If outgoing access is permitted on your CUG and you present an outgoing call without designating a
preferential CUG, then your CUG assumes the call is meant either for the open network or for the
preferential CUG.
A single CUG specified at a DCE interface is treated as the preferential CUG.
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Configuring X.25 and LAPB
CUG Service Access and Properties
Incoming and Outgoing Access CUGs
CUG service with incoming access allows you to receive incoming calls from the open part of the network
and from DTE devices belonging to other outgoing access CUGs. If the DTE does not subscribe to
incoming access, any incoming call without the CUG membership selection facility will not be accepted.
A CUG with outgoing access allows you to make outgoing calls to the open part of the network and to DTE
devices with incoming access capability. Subscribing to the outgoing access CUG allows a DTE to belong
to one or more CUGs and to originate calls to DTE devices in the open part of the network (DTE devices
not belonging to any CUGs) and to DTE devices belonging to incoming access CUGs. If the DTE has not
subscribed to outgoing access, the outgoing packets must contain a valid CUG membership selection
facility. If a CUG membership selection facility is not present, the local DCE defaults to the preferential
CUG, or rejects the call if a preferential CUG is not specified.
Incoming and Outgoing Calls Barred Within a CUG
When a DTE wishes to initiate only outgoing calls, it specifies "incoming calls barred." With this CUG
option subscribed to, a subscriber DTE is permitted only to originate calls and not to receive calls within
the CUG. The DCE will clear an incoming call before it reaches the DTE.
If a DTE subscribes to the "outgoing calls barred" option, it is permitted to receive calls but not to originate
calls within the CUG. An attempted outgoing call will be cleared by the DCE, which in turn will notify the
DTE of its actions.
CUG Service Access and Properties
Note
If you do not want to enable the x25 subscribe cug-servicecommand, you will be subscribed to CUG
service automatically the first time you subscribe to a CUG (using the x25 subscribe local-cug command),
with CUG service default settings of no incoming and no outgoing access.
You must establish X.25 DCE encapsulation and X.25 CUG service on the interface to enable this feature.
Within the x25 subscribe cug-service command, establish the type of CUG public access (incoming or
outgoing) you want. If you do not enter this command, the default will be enabled.
To set up the individual CUGs, use the x25 subscribe local-cug command to specify each local CUG and
map it to a network CUG, setting the access properties of the local CUG--no-incoming, no-outgoing,
preferential, all, or none--at the same time.
POP with No CUG Access
Caution
This configuration is critical to enforcing full CUG security on your network. You must conduct this
configuration on every POP in your network. If you do not configure this for all POPs in your network, you
will not have a secure network, and a security breach could occur.
With the POP configuration of no individual CUG subscriptions, the POP is a member of the open network.
Even though it does not have a CUG attached, you must configure CUG security on it to ensure that the rest
of your network remains secure. The POP has CUG incoming access and outgoing access permitted--the
least restrictive setting. The POP will allow calls that do not require CUG authorization to and from the
open network, but it will refuse any CUG-specified calls because the POP does not belong to a CUG. A call
from an intranetwork connection with no CUG selected is permitted as incoming access from the open
network, but a call that requires CUG access will be refused.
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Configuring X.25 and LAPB
POP with Access Restricted to One CUG
POP with Access Restricted to One CUG
In the POP configuration with one CUG subscribed, it is important to have no public access permitted on it.
You do this by configuring the default setting (no incoming and no outgoing access) for the x25 subscribe
cug-service command. When an outgoing call not specifying a CUG is made, the POP assumes the call to
be for its one subscribed CUG. An incoming call that does not specify that CUG is rejected. This single
CUG configuration assumes the CUG to be the preferential CUG.
POP with Multiple CUGs and No Public Access
With the POP configuration of multiple CUGs and no public access permitted, the only difference from the
POP configuration with one subscribed CUG is that one of the CUGs must be chosen as preferential. If you
do not specify a preferential CUG, no calls can be made or accepted. Notice the omission of the keywords
from the x25 subscribe cug-service command. This omission enables the default settings of no incoming
and no outgoing access.
POP with Multiple CUGs and Public Access
The least restrictive POP configuration is a POP configured to allow public access to members of several
CUG and to originate and receive calls from the open network (that is, to or from users that do not
subscribe to one of the CUGs to which this POP subscribes). Configuring the POP with multiple CUGs and
public access is achieved using the x25 subscribe cug-service command with the addition of the keywords
incoming-access and outgoing-access to allow calls to be made and received to and from outside hosts not
in the specified CUG network.
To set up the individual CUGs, use the x25 subscribe local-cug command to specify each local CUG and
map it to a network CUG, setting the access properties of the local CUG--no-incoming, no-outgoing,
preferential, all, or none--at the same time.
An outgoing call may select any of the local CUGs or not. When no CUG is selected, it is assumed that the
call is intended for the open network. The call will be refused if it specifies a local CUG different from the
one to which the POP is subscribed. An incoming call may or may not select related network CUGs. If no
CUG is selected, the call is accepted as coming from the open network. A call that requires access to a
different CUG will be refused.
CUG Selection Facility Suppression
A CUG selection facility is a specific encoding element that can be presented in a call request or an
incoming call. A CUG selection facility in a call request allows the source DTE to identify the CUG within
which it is placing the call. A CUG selection facility in an incoming call allows the destination DTE to
identify the CUG to which both DTEs belong.
You can configure an X.25 DCE interface or X.25 profile with a DCE station type to selectively remove
the CUG selection facility before presenting an incoming call packet to a subscribed DTE. The CUG
selection facility can be removed from incoming call packets destined for the preferential CUG only or for
all CUGs. You can also remove the selection facility from a CUG with outgoing access (CUG/OA). The
CUG selection facility suppression mechanism does not distinguish between CUGs and CUG/OAs.
Note
The CUG Selection Facility Suppress Option feature will not in any way compromise CUG security.
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DDN or BFE X.25
DDN
CUG selection facility supression is supported by X.25 over Frame Relay (Annex G). If Annex G is being
used, you must configure CUG selection facility supression in an X.25 profile.
DDN or BFE X.25
•
•
•
•
DDN, page 39
Understanding DDN X.25 Dynamic Mapping, page 39
IP Precedence Handling, page 40
Blacker Front End X.25, page 40
DDN
The Defense Data Network (DDN) X.25 protocol has two versions: Basic Service and Standard Service.
Cisco System’s X.25 implementation supports only the Standard Service which also includes Blacker Front
End (BFE).
DDN X.25 Standard Service requires that the X.25 data packets carry IP datagrams. The DDN packet
switching nodes (PSNs) can extract the IP datagram from within the X.25 packet and pass data to another
Standard Service host.
The DDN X.25 Standard is the required protocol for use with DDN PSNs. The Defense Communications
Agency (DCA) has certified Cisco Systems’ DDN X.25 Standard implementation for attachment to the
Defense Data Network. As part of the certification, Cisco IOS software is required to provide a scheme for
dynamically mapping Internet addresses to X.121 addresses.
Understanding DDN X.25 Dynamic Mapping
The DDN X.25 standard implementation includes a scheme for dynamically mapping all classes of IP
addresses to X.121 addresses without a table. This scheme requires that the IP and X.121 addresses
conform to the formats shown in the figures below. These formats segment the IP addresses into network
(N), host (H), logical address (L), and PSN (P) portions. For the BFE encapsulation, the IP address is
segmented into Port (P), Domain (D), and BFE ID number (B). The DDN algorithm requires that the host
value be less than 64.
Figure 6
DDN IP Address Conventions
Figure 7
BFE IP Address Conventions
The DDN conversion scheme uses the host and PSN portions of an IP address to create the corresponding
X.121 address. The DDN conversion mechanism is limited to Class A IP addresses; however, the Cisco
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X.25 Remote Failure Detection
IP Precedence Handling
IOS software can convert Class B and Class C addresses as well. As indicated, this method uses the last
two octets of a Class B address as the host and PSN identifiers, and the upper and lower four bits in the last
octet of a Class C address as the host and PSN identifiers, respectively. The BFE conversion scheme
requires a Class A IP address.
The DDN conversion scheme uses a physical address mapping if the host identifier is numerically less than
64. (This limit derives from the fact that a PSN cannot support more than 64 nodes.) If the host identifier is
numerically larger than 64, the resulting X.121 address is called a logical address . The DDN does not use
logical addresses.
The format of physical DDN X.25/X.121 addresses is ZZZZFIIIHHZZ(SS). Each character represents a
digit, described as follows:
•
•
•
•
•
•
ZZZZ represents four zeros.
F is zero to indicate a physical address.
III represents the PSN octet from the IP address padded with leading zeros.
HH is the host octet from the IP address padded with leading zeros.
ZZ represents two zeros.
(SS) represents the optional and unused subaddress.
The physical and logical mappings of the DDN conversion scheme always generate a 12-digit X.121
address. Subaddresses are optional; when added to this scheme, the result is a 14-digit X.121 address. The
DDN does not use subaddressing.
Packets using routing and other protocols that require broadcast support can successfully traverse X.25
networks, including the DDN. This traversal requires the use of network protocol-to-X.121 maps, because
the router must know explicitly where to deliver broadcast datagrams. (X.25 does not support broadcasts.)
You can mark network protocol-to-X.121 map entries to accept broadcast packets; the router then sends
broadcast packets to hosts with marked entries. For DDN or BFE operation, the router generates the
interface X.121 addresses from the interface IP address using the DDN or BFE mapping technique.
IP Precedence Handling
Using Standard Service, the DDN can be configured to provide separate service for datagrams with high
precedence values. When IP precedence handling is enabled, the router uses a separate X.25 SVC to handle
each of four precedence classes of IP traffic--routine, priority, immediate, and other. An IP datagram is
transmitted only across the SVC that is configured with the appropriate precedence.
By default, the DDN X.25 software opens one VC for all types of service values. Verify that your host does
not send nonstandard data in the TOS field. Nonstandard data can cause multiple, wasteful VCs to be
created.
Blacker Front End X.25
For environments that require a high level of security, the Cisco IOS software supports attachment to
Defense Data Network (DDN) Blacker Front End (BFE) equipment. BFE encapsulation operates to map
between Class A IP addresses and the X.121 addresses expected by the BFE encryption device.
X.25 Remote Failure Detection
X.25 remote failure detection is important because after a primary link failure, the router can establish a
secondary link and continue sending data. The router detects a call failure and uses a secondary route to
send subsequent packets to the remote destination, at the same time making periodic attempts to reconnect
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Configuring X.25 and LAPB
Blacker Front End X.25
to its primary link. The number of these attempts and the interval between such attempts is controlled using
the x25 retry command. The failed link is marked up again when any of the following occurs:
•
•
•
An attempt to reestablish the link via the retry mechanism is successful.
An incoming call is received on the subinterface.
The X.25 packet layer on the interface is restarted.
X.25 remote failure detection needs to be manually configured on each intended subinterface. However,
because it is a per-destination configuration rather than a per-user configuration, you need it enabled only
on the subinterface requiring the retry option--typically your primary interface. This feature is not
automatically enabled and only responds to failed outgoing call attempts. The feature applies only to pointto-point subinterfaces and works only on SVCs. It is not necessary if you are running IP routing, because IP
routing already implements alternate routing. This feature is targeted at environments that have static IP
routing across an X.25 network, where these static IP routes currently need to be manually added to the
route tables.
The x25 retry command is activated by a call failure notification. Retry occurs only with calls initiated on
a subinterface configured with the x25 retry command. This command works only when no VCs are up.
When reconnection occurs, traffic begins to reuse the primary interface. This resetting of the line protocol
to up is the last activity that the x25 retry command conducts. Issuing the clear x25 command on the
remote failure detection configured interface, or receiving a call during retry, will disable the x25 retry and
the subinterface will be marked "up." An incoming call can be conducted in a way similar to how the ping
command is used to check connectivity (by definition, a successful incoming call indicates that
connectivity is functioning). Also, if the router reaches its retry attempts limit, the x25 retry command will
discontinue and the subinterface will remain down.
X.25 remote failure detection is designed to work with any network layer routed protocol. However, the
feature depends on the ability of the protocol to handle more than one static route to the same destination at
the same time. Currently, only IP can accomplish this multistatic route handling.
Alternatively, X.25 remote failure detection can be used to activate a backup link should the subinterface
configured for retry be marked down via the retry mechanism. See the X.25 Remote Failure Detection and
the Backup Interface, page 75 configuration tasks for further details.
The benefits of this feature are network cost savings because IP routing updates (requiring dynamic but
costly network connectivity) are not necessary; improved responsiveness and versatility of X.25 primary
and alternate links; and more robust networking options for data transmission.
The figure below shows how X.25 remote failure detection works:
1 The data cannot reach its destination using its primary route.
2 A call failure notification is sent to the transmitting router.
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X.29 Access Lists
How to Configure LAPB
3 The x25 retry command is activated, and IP then activates the preassigned secondary route in its route
table and begins sending data. The x25 retry command also shuts down subinterface 1.1 and begins its
retry attempts on this link.
Figure 8
X.25 Remote Failure Detection in Action over an X.25 Cloud
X.29 Access Lists
Protocol translation software supports access lists, which make it possible to limit access to the access
server from X.25 hosts. Access lists take advantage of the message field defined by Recommendation X.29,
which describes procedures for exchanging data between two PADs or between a PAD and a DTE device.
When configuring protocol translation, you can specify an access list number with each translate
command. When translation sessions result from incoming PAD connections, the corresponding X.29
access list is used. Refer to the Cisco IOS Dial Technologies Command Reference for more information
about the translate command.
An access list can contain any number of lines. The lists are processed in the order in which you type the
entries. The first match causes the permit or deny condition. If an X.121 address does not match any of the
entries in the access list, access is denied.
When applying the access list to a virtual terminal line, the access list number is used for incoming TCP
access, for incoming local-area transport (LAT) access, and for incoming PAD access. For TCP access, the
protocol translator uses the defined IP access lists. For LAT access, the protocol translator uses the defined
LAT access list. For incoming PAD connections, the protocol translator uses an X.29 access list. If you
want to have access restrictions only on one of the protocols, you can create an access list that permits all
addresses for the other protocol.
How to Configure LAPB
•
•
•
•
Configuring a LAPB Datagram Transport, page 43
Selecting an Encapsulation and Protocol, page 43
Configuring Compression over LAPB, page 43
Configuring Compression over Multi-LAPB, page 44
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Configuring a LAPB Datagram Transport
How to Configure LAPB
•
Configuring Transparent Bridging over Multiprotocol LAPB, page 44
Configuring a LAPB Datagram Transport
To set the appropriate LAPB encapsulation to run datagrams over a serial interface, use the following
command in global configuration mode. One end of the link must be a DTE device, and the other must be
DCE. Because the default serial encapsulation is HDLC, you must explicitly configure a LAPB
encapsulation method. You should shut down the interface before changing the encapsulation.
Command
Purpose
Router(config)#
interface type
Specifies a serial interface.
number
Selecting an Encapsulation and Protocol
To select an encapsulation and protocol (if you are using a single protocol), or to select the multiple
protocol operation, use one or more of the following commands in interface configuration mode:
Command
Purpose
Router(config-if)#
[protocol]7
encapsulation lapb dce
Router(config-if)# encapsulation lapb dte
[protocol]Selecting an Encapsulation and Protocol,
page 43
Router(config-if)#
Enables encapsulation of a single protocol on the
line using DTE operation.
encapsulation lapb dce
Enables use of multiple protocols on the line using
DCE operation.
encapsulation lapb dte
Enable use of multiple protocols on the line using
DTE operation.
multi
Router(config-if)#
Enables encapsulation of a single protocol on the
line using DCE operation.
multi8
Configuring Compression over LAPB
To configure compression over LAPB, use the following commands in interface configuration mode:
SUMMARY STEPS
1. Router(config-if)# encapsulation lapb[protocol]
2. Router(config-if)# compress[predictor | stac]
7
Single protocol LAPB defaults to IP encapsulation.
8 Multiprotocol LAPB does not support source-route bridging or TCP/IP header compression, but does support transparent bridging. A multiprotocol LAPB
encapsulation supports all of the protocols available to a single-protocol LAPB encapsulation plus transparent bridging.
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Configuring Compression over Multi-LAPB
How to Configure LAPB
DETAILED STEPS
Command or Action
Purpose
Step 1 Router(config-if)# encapsulation lapb[protocol]
Enables encapsulation of a single protocol on the serial line.
Step 2 Router(config-if)# compress[predictor | stac]
Enables compression.
Configuring Compression over Multi-LAPB
To configure compression over multi-LAPB, use the following commands in interface configuration mode:
SUMMARY STEPS
1. Router(config-if)# encapsulation lapb multi
2. Router(config-if)# compress[predictor | stac]
DETAILED STEPS
Command or Action
Purpose
Step 1 Router(config-if)# encapsulation lapb multi
Enables encapsulation of multiple protocols on the serial line.
Step 2 Router(config-if)# compress[predictor | stac]
Enables compression.
When using compression, adjust the maximum transmission unit (MTU) for the serial interface and the
LAPB N1 parameter as in the following example, to avoid informational diagnostics regarding excessive
MTU or N1 sizes:
interface serial 0
encapsulation lapb
compress predictor
mtu 1509
lapb n1 12072
For information about configuring X.25 TCP/IP header compression and X.25 payload compression, see
the sections Setting X.25 TCP IP Header Compression, page 54 and Configuring X.25 Payload
Compression, page 55.
Configuring Transparent Bridging over Multiprotocol LAPB
To configure transparent bridging over multiprotocol LAPB, use the following commands beginning in
global configuration mode:
SUMMARY STEPS
1. Router(config)# interface serial number
2. Router(config-if)# no ip address
3. Router(config-if)# encapsulation lapb multi
4. Router(config-if)# bridge-group bridge-group
5. Router(config)# bridge bridge-group protocol {ieee | dec}
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Configuring X.25 and LAPB
How to Configure X.25
DETAILED STEPS
Command or Action
Purpose
Step 1 Router(config)# interface serial number
Enters interface configuration mode.
Step 2 Router(config-if)# no ip address
Assigns no IP address to the interface.
Step 3 Router(config-if)# encapsulation lapb multi
Configures multiprotocol LAPB encapsulation.
Note You must use the encapsulation lapb multicommand rather
than the encapsulation lapb protocol bridge command to
configure transparent bridging over multiprotocol LAPB.
Step 4 Router(config-if)# bridge-group bridge-group
Assigns the interface to a bridge group.
Step 5 Router(config)# bridge bridge-group protocol
{ieee | dec}
Defines the type of Spanning-Tree Protocol.
How to Configure X.25
LAPB frame parameters can be modified to optimize X.25 operation and these features can coexist on an
X.25 interface.
Default parameters are provided for X.25 operation. However, you can change the settings to meet the
needs of your X.25 network or as defined by your X.25 service supplier. Cisco also provides additional
configuration settings to optimize your X.25 usage.
Note
If you connect a router to an X.25 network, use the parameters set by your network administrator for the
connection. These parameters are described in the sections "Configuring an X.25 Interface, page 46" and
"Modifying LAPB Protocol Parameters, page 11". Also, note that the X.25 Level 2 parameters described in
the section "Modifying LAPB Protocol Parameters, page 11" affect X.25 Level 3 operations.
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Configuring an X.25 Interface, page 46
Configuring Additional X.25 Interface Parameters, page 49
Configuring an X.25 Datagram Transport, page 53
Configuring Additional X.25 Datagram Transport Features, page 55
Configuring X.25 Routing, page 59
Configuring Additional X.25 Routing Features, page 62
Configuring DNS-Based X.25 Routing, page 65
Configuring X.25 over Frame Relay (Annex G), page 67
Configuring CMNS Routing, page 67
Configuring Priority Queueing or Custom Queueing for X.25, page 68
Configuring X.25 Closed User Groups, page 69
Configuring DDN or BFE X.25, page 73
Configuring X.25 Remote Failure Detection, page 74
Creating X.29 Access Lists, page 77
Creating an X.29 Profile Script, page 78
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Configuring an X.25 Interface
Configuring X.25 Encapsulation
•
Monitoring and Maintaining LAPB and X.25, page 78
Configuring an X.25 Interface
•
•
•
•
•
•
•
•
Configuring X.25 Encapsulation, page 46
Setting the Virtual Circuit Ranges, page 46
Setting the Packet-Numbering Modulo, page 47
Setting the X.121 Address, page 47
Configuring X.25 Switch Local Acknowledgment, page 47
Enabling Flow Control Parameter Negotiation, page 48
Setting Default Flow Control Values, page 48
Enabling Asymmetrical Flow Control, page 49
Configuring X.25 Encapsulation
To configure the mode of operation and encapsulation type for a specified interface, use the following
command in interface configuration mode:
Command
Purpose
Router(config-if)# encapsulation
dce] [[ddn | bfe] | [ietf]]
x25 [dte
Sets the X.25 mode of operation.
|
Setting the Virtual Circuit Ranges
Note
Each of these parameters can range from 1 to 4095. The values for these parameters must be the same on
both ends of the X.25 link. For connection to a PDN, these values must be set to the values assigned by the
network. An SVC range is unused if its lower and upper limits are set to 0; other than this use for marking
unused ranges, VC 0 is not available.
To configure X.25 VC ranges, use the following commands in interface configuration mode:
Command
Purpose
Router(config-if)#
x25 lic circuit-number
Sets the lowest incoming-only circuit number. The
default is 0.
Router(config-if)#
x25 hic circuit-number
Sets the highest incoming-only circuit number. The
default is 0
Router(config-if)#
x25 ltc circuit-number
Sets the lowest two-way circuit number. The
default is 1.
Router(config-if)#
x25 htc circuit-number
Sets the highest two-way circuit number. The
default is 1024 for X.25; 4095 for CMNS.
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Configuring X.25 and LAPB
Setting the Packet-Numbering Modulo
Command
Purpose
Router(config-if)#
x25 loc circuit-number
Sets the lowest outgoing-only circuit number. The
default is 0.
Router(config-if)#
x25 hoc circuit-number
Sets the highest outgoing-only circuit number. The
default is 0.
Setting the Packet-Numbering Modulo
To set the packet-numbering modulo, use the following command in interface configuration mode:
Command
Purpose
Router(config-if)#
x25 modulo {8
|
128}
Sets the packet-numbering modulo.
Setting the X.121 Address
To set the X.121 address, use the following command in interface configuration mode:
Command
Purpose
Router(config-if)#
x25 address x121-address
Sets the X.121 address.
Configuring X.25 Switch Local Acknowledgment
To configure local acknowledgment, use the following command in global configuration mode:
Purpose
Command
Router(config)#
x25 routing acknowledge
local
•
Enables X.25 switching with local
acknowledgment.
Verifying Local Acknowledgement, page 47
Verifying Local Acknowledgement
To verify that local acknowledgment is configured on your router, use the show runningconfigurationcommand in EXEC mode. In the following example, X.25 encapsulation has been set on
serial interface 1/4 with acknowledgment set to "local":
Router# show running-configuration
x25 routing acknowledge local
You can also use the show protocol command in EXEC mode to verify local acknowledgment:
Router# show protocol
Global values:
Internet Protocol routing is enabled
X.25 routing is enabled, acknowledgements have local significance only
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Configuring X.25 and LAPB
Enabling Flow Control Parameter Negotiation
Enabling Flow Control Parameter Negotiation
To control packet transmission flow values on the interface, use one or more of the flow control commands
in interface configuration mode.
Command
Router(config-if)#
{always | never}
Purpose
Determines flow control parameter negotiation
x25 subscribe flow-control behavior.
Router(config-if)# x25 subscribe windowsize
{permit wmin wmax | target wmin wmax}
Router(config-if)# x25 subscribe
{permit pmin pmax | target pmin
•
packetsize
pmax}
Sets permitted and target ranges for window size
negotiation.
Sets permitted and target ranges for packet size
negotiation.
Verifying Flow Control Parameter Negotiation, page 48
Verifying Flow Control Parameter Negotiation
To verify flow control parameter settings, use the show running-configurationcommand in EXEC mode.
In the following example, X.25 encapsulation has been set on serial interface 1/4 with flow control
negotiation set to "always." Permitted packet sizes are set at 64 (minimum) and 1024 (maximum), with
target packet sizes set at 128 (minimum) and 1024 (maximum). Permitted window sizes are set at 1
(minimum) and 7 (maximum), with target window sizes set at 2 (minimum) and 4 (maximum).
Router# show running-configuration
x25 subscribe flow-control always
x25 subscribe packetsize permit 64 1024 target 128 1024
x25 subscribe windowsize permit 1 7 target 2 4
Setting Default Flow Control Values
•
•
Setting Default Window Sizes, page 48
Setting Default Packet Sizes, page 49
Setting Default Window Sizes
To set the default window sizes, use the following commands in interface configuration mode:
SUMMARY STEPS
1. Router(config-if)# x25 win packets
2. Router(config-if)# x25 wout packets
DETAILED STEPS
Step 1
Command or Action
Purpose
Router(config-if)# x25 win packets
Sets input maximum window size.
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Configuring Additional X.25 Interface Parameters
Setting Default Packet Sizes
Step 2
Command or Action
Purpose
Router(config-if)# x25 wout packets
Sets output maximum window size.
Setting Default Packet Sizes
To set the default input and output maximum packet sizes, use the following commands in interface
configuration mode:
SUMMARY STEPS
1. Router(config-if)# x25 ips bytes
2. Router(config-if)# x25 ops bytes
DETAILED STEPS
Command or Action
Purpose
Step 1
Router(config-if)# x25 ips bytes
Sets input maximum packet size.
Step 2
Router(config-if)# x25 ops bytes
Sets output maximum packet size.
Enabling Asymmetrical Flow Control
To use asymmetrical flow control effectively, use the x25 subscribe flow-control never command to
disable flow control parameter negotiation, and use the x25 routing acknowledge localcommand to enable
local acknowledgment.
SUMMARY STEPS
1. Router(config)# x25 routing acknowledge local
2. Router(config-if)# x25 subscribe flow-control never
DETAILED STEPS
Purpose
Command or Action
Step 1 Router(config)# x25 routing acknowledge local
Enables X.25 switching with local acknowledgment.
Step 2 Router(config-if)# x25 subscribe flow-control never
Disables flow control parameter negotiation behavior.
Configuring Additional X.25 Interface Parameters
•
•
•
•
•
Configuring X.25 Failover, page 50
Configuring the X.25 Level 3 Timers, page 51
Configuring X.25 Addresses, page 51
Establishing a Default VC Protocol, page 52
Disabling PLP Restarts, page 52
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Configuring X.25 and LAPB
Configuring X.25 Failover
Configuring X.25 Failover
You can configure X.25 Failover on an X.25 interface or X.25 profile.
•
•
•
Configuring X.25 Failover on an Interface, page 50
Configuring X.25 Failover on an X.25 Profile, page 50
Verifying X.25 Failover, page 51
Configuring X.25 Failover on an Interface
To configure X.25 failover on an interface, use the following commands beginning in global configuration
mode:
SUMMARY STEPS
1. Router(config)# interface type number
2. Router(config-if)# encapsulation x25
3. Router(config-if)# x25 fail-over seconds interface type number [dlci | MAC address
DETAILED STEPS
Command or Action
Purpose
Step 1 Router(config)# interface type number
Configures an interface type and enters interface configuration mode.
Step 2 Router(config-if)# encapsulation x25
Specifies the operation of a serial interface as an X.25 device.
Step 3 Router(config-if)# x25 fail-over seconds
interface type number [dlci | MAC address
Specifies a secondary interface and sets the number of seconds for
which the primary interface must be up before the secondary interface
resets.
Configuring X.25 Failover on an X.25 Profile
To configure X.25 failover on an X.25 profile, use the following commands beginning in global
configuration mode:
SUMMARY STEPS
1. Router(config)# x25 profile name {dce | dte | dxe}
2. Router(config-x25)# x25 fail-over seconds interface type number [dlci | MAC address
DETAILED STEPS
Command or Action
Step 1 Router(config)# x25 profile name {dce | dte | dxe}
Purpose
Configures an X.25 profile.
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Configuring X.25 and LAPB
Verifying X.25 Failover
Command or Action
Purpose
Step 2 Router(config-x25)# x25 fail-over seconds interface type
number [dlci | MAC address
Specifies a secondary interface and sets the number of
seconds for which the primary interface must be up
before the secondary interface resets.
Example:
Verifying X.25 Failover
To display information about the X.25 Failover feature, use the following EXEC command:
Command
Router#
Purpose
show x25 context
Displays information about all X.25 links.
Configuring the X.25 Level 3 Timers
To set the event timers, use any of the following commands in interface configuration mode:
Command
Purpose
Router(config-if)#
x25 t20 seconds
Router(config-if)#
x25 t10 seconds
Router(config-if)#
x25 t21 seconds
Router(config-if)#
x25 t11 seconds
Router(config-if)#
x25 t22 seconds
Router(config-if)#
x25 t12 seconds
Router(config-if)#
x25 t23 seconds
Router(config-if)#
x25 t13 seconds
Sets DTE T20 Restart Request timeout.
Sets DCE T10 Restart Indication timeout.
Sets DTE T21 Call Request timeout.
Sets DCE T11 Incoming Call timeout.
Sets DTE T22 Reset Request timeout.
Sets DCE T12 Reset Indication timeout.
Sets DTE T23 Clear Request timeout.
Sets DCE T13 Clear Indication timeout.
For an example of setting the event timers, see the section "DDN X.25 Configuration Example, page 98"
later in this chapter.
Configuring X.25 Addresses
•
•
Configuring an Interface Alias Address, page 52
Suppressing or Replacing the Calling Address, page 52
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Configuring X.25 and LAPB
Configuring an Interface Alias Address
•
Suppressing the Called Address, page 52
Configuring an Interface Alias Address
To configure an alias, use the following command in interface configuration mode:
Command
Purpose
Router(config-if)# x25
pattern [cud pattern]
alias x121-address-
Enables an alias X.121 address for the interface.
Suppressing or Replacing the Calling Address
To suppress or replace the calling address, use the appropriate command in interface configuration mode:
Command
Router(config-if)#
Purpose
x25 suppress-calling-
Suppresses the calling (source) X.121 address in
outgoing calls.
x25 use-source-address
Replaces the calling (source) X.121 address in
switched calls.
address
Router(config-if)#
Suppressing the Called Address
To suppress the called address, use the following command in interface configuration mode:
Command
Router(config-if)#
Purpose
x25 suppress-called-
address
Suppresses the called (destination) X.121 address in
outgoing calls.
Establishing a Default VC Protocol
To configure either PAD or IP encapsulation treatment of unidentified calls, use the following command in
interface configuration mode:
Purpose
Command
Router(config-if)#
x25 default {ip
|
pad}
Establishes a default VC protocol.
Disabling PLP Restarts
To disable PLP restarts, use the following command in interface configuration mode:
Command
Router(config-if)#
Purpose
no x25 linkrestart
Disables packet-level restarts.
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Configuring an X.25 Datagram Transport
Configuring Point-to-Point and Multipoint Subinterfaces
Configuring an X.25 Datagram Transport
•
•
•
•
•
Configuring Point-to-Point and Multipoint Subinterfaces, page 53
Mapping Protocol Addresses to X.121 Addresses, page 53
Establishing an Encapsulation PVC, page 54
Setting X.25 TCP IP Header Compression, page 54
Configuring X.25 Bridging, page 54
Configuring Point-to-Point and Multipoint Subinterfaces
To create and configure a subinterface, use the Step 1 command and one or both of the Step 2 commands
beginning in global configuration mode:
SUMMARY STEPS
1. Router(config)# interface serial type number . subinterface-number [point-to-point | multipoint]
2. Do one of the following:
•
•
•
•
Router(config-subif)# x25 map protocol address [protocol2 address2[... [protocol9 address9]]]
x121-address [option]
Router(config-subif)# x25 pvc circuit protocol address [protocol2 address2 [...[protocol9
address9]]] x121-address [option]
DETAILED STEPS
Command or Action
Purpose
Step 1 Router(config)# interface serial type number . subinterface-number [pointto-point | multipoint]
Creates a point-to-point or multipoint
subinterface.
Step 2 Do one of the following:
Configures an X.25 encapsulation map for
the subinterface.
•
•
•
•
Router(config-subif)# x25 map protocol address [protocol2 address2[...
[protocol9 address9]]] x121-address [option]
Establishes an encapsulation PVC for the
subinterface.
Router(config-subif)# x25 pvc circuit protocol address [protocol2
address2 [...[protocol9 address9]]] x121-address [option]
Mapping Protocol Addresses to X.121 Addresses
•
•
Mapping Datagram Addresses to X.25 Hosts, page 53
Configuring PAD Access, page 54
Mapping Datagram Addresses to X.25 Hosts
To establish an X.25 map, use the following command in interface configuration mode:
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Configuring X.25 and LAPB
Configuring PAD Access
Command
Router(config-if)# x25 map protocol
address [protocol2 address2 [...[protocol9
address9]]] x121-address [option]
Purpose
Maps one or more host protocol addresses to the X.
121 address of the host.
Configuring PAD Access
To restrict PAD connections only to statically mapped X.25 hosts, use the following commands in interface
configuration mode:
SUMMARY STEPS
1. Router(config-if)# x25 pad-access
2. Router(config-if)# x25 map pad x121-address[option]
DETAILED STEPS
Command or Action
Purpose
Step 1
Router(config-if)# x25 pad-access
Restricts PAD access.
Step 2
Router(config-if)# x25 map pad x121-address[option]
Configures a host for PAD access.
Establishing an Encapsulation PVC
To establish a PVC, use the following command in interface configuration mode:
Command
Router(config-if)# x25 pvc circuit protocol
address [protocol2 address2 [...[protocol9
address9]]] x121-address [option]
Purpose
Sets an encapsulation PVC.
Setting X.25 TCP IP Header Compression
To set up a separate VC for X.25 THC, use the following command in interface configuration mode:
Command
Router(config-if)# x25 map compressedtcp
ip-address [protocol2 address2 [...[protocol9
address9]]] x121-address [option]
Purpose
Allows a separate VC for compressed packets.
Configuring X.25 Bridging
To enable the X.25 bridging capability, use the following command in interface configuration mode:
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Configuring Additional X.25 Datagram Transport Features
Configuring X.25 Payload Compression
Command
Purpose
x25 map bridge x121address broadcast [option]
Defines bridging of X.25 frames.
Router(config-if)#
Configuring Additional X.25 Datagram Transport Features
•
•
•
•
•
•
•
•
Configuring X.25 Payload Compression, page 55
Configuring the Encapsulation VC Idle Time, page 55
Increasing the Number of VCs Allowed, page 56
Configuring the Ignore Destination Time, page 56
Establishing the Packet Acknowledgment Policy, page 56
Configuring X.25 User Facilities, page 56
Defining the VC Packet Hold Queue Size, page 58
Restricting Map Usage, page 59
Configuring X.25 Payload Compression
To enable payload compression over X.25, use the following command in interface configuration mode:
Command
Purpose
Router(config-if)# x25 map protocol
address [protocol2 address2 [...[protocol9
address9]]] x121-address compress
Enables payload compression over X.25.
Configuring the Encapsulation VC Idle Time
The Cisco IOS software can clear a datagram transport or PAD SVC after a set period of inactivity. Routed
SVCs are not timed for inactivity.
To set the time, use the following commands in interface configuration mode:
SUMMARY STEPS
1. Router(config-if)# x25 idle minutes
2. Router(config-if)# x25 map protocol address[protocol2 address2 [...[protocol9 address9]]] x121address idle minutes
DETAILED STEPS
Command or Action
Purpose
Step 1 Router(config-if)# x25 idle minutes
Sets an idle time for clearing encapsulation.
Step 2 Router(config-if)# x25 map protocol address[protocol2 address2 [...
[protocol9 address9]]] x121-address idle minutes
Specifies idle time for clearing SVCs of a map.
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Configuring X.25 and LAPB
Increasing the Number of VCs Allowed
Increasing the Number of VCs Allowed
For X.25 datagram transport, you can establish up to eight VCs to one host for each map. To increase the
number of VCs allowed, use one or both of the following commands in interface configuration mode:
Command
Router(config-if)#
Purpose
x25 nvc count
Router(config-if)# x25 map protocol
address [protocol2 address2 [...[protocol9
address9]]] x121-address nvc count
Specifies the default maximum number of SVCs
that can be open simultaneously to one host for
each map.
Specifies the maximum number of SVCs allowed
for a map.
Configuring the Ignore Destination Time
Upon receiving a Clear for an outstanding datagram transport Call Request, the X.25 encapsulation code
immediately tries another Call Request if it has more traffic to send. This action can overrun some X.25
switches. To define the number of minutes for which the Cisco IOS software will prevent calls from going
to a previously failed destination, use the following command in interface configuration mode (incoming
calls will still be accepted and cancel the timer):
Command
Router(config-if)#
Purpose
x25 hold-vc-timer minutes
Configures the ignore destination time.
Establishing the Packet Acknowledgment Policy
To establish the acknowledgment threshold, use the following command in interface configuration mode
(the packet acknowledgment threshold also applies to encapsulation PVCs):
Command
Router(config-if)#
Purpose
x25 threshold delay-count
Sets data packet acknowledgement threshold.
Configuring X.25 User Facilities
To set the supported X.25 user facilities options, use one or more of the following commands in interface
configuration mode:
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Configuring X.25 and LAPB
Configuring X.25 User Facilities
Command
Purpose
Router(config-if)#
x25 facility cug number
Selects the closed user group (CUG).
or
x25 map protocol address [protocol2 address2
[...[protocol9 address9]]] x121-address
cug group-number
Router(config-if)#
x25 facility packetsize in-
size out-size
Sets the flow control parameter negotiation values
to be requested on outgoing calls.
or
Router(config-if)# x25 map protocol address
[protocol2 address2 [...[protocol9
address9]]] x121-address packetsize in-size
out-size
or
Router(config-if)#
x25 facility windowsize in-
size out-size
or
Router(config-if)# x25 map protocol
[protocol2 address2 [...[protocol9
address9]]] x121-address windowsize
address
in-size
out-size
Router(config-if)#
Sets reverse charging.
x25 facility reverse
or
Router(config-if)# x25 map protocol
[protocol2 address2 [...[protocol9
address9]]] x121-address reverse
Router(config-if)#
address
x25 accept-reverse
Allows reverse charging acceptance.
or
Router(config-if)# x25 map protocol address
[protocol2 address2 [...[protocol9
address9]]] x121-address accept-reverse
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Configuring X.25 and LAPB
Defining the VC Packet Hold Queue Size
Command
Router(config-if)#
Purpose
x25 facility throughput
Selects throughput class negotiation.
in out
or
Router(config-if)# x25 map protocol
[protocol2 address2 [...[protocol9
address9]]] x121-address throughput
Router(config-if)#
address
in out
x25 facility transit-delay
Selects transit delay.
milliseconds
or
Router(config-if)# x25 map protocol address
[protocol2 address2 [...[protocol9
address9]]] x121-address transit-delay
milliseconds
Router(config-if)#
x25 facility roa name
Sets which Recognized Operating Agency (ROA)
to use.
or
Router(config-if)# x25 map protocol
address [protocol2 address2 [...[protocol9
address9]]] x121-address roa name
Router(config-if)# x25 map protocol
address
[protocol2 address2 [...[protocol9
address9]]] x121-address nuid username
Sets the Cisco standard network user identification.
password
Router(config-if)# x25 map protocol
address [protocol2 address2 [...[protocol9
address9]]] x121-address nudata string
Sets a user-defined network user identification,
allowing the format to be determined by your
network administrator.
Defining the VC Packet Hold Queue Size
To define the maximum number of packets that can be held while a VC is unable to send data, use the
following command in interface configuration mode. A hold queue size of an encapsulation VC is
determined when it is created; the x25 hold-queue command does not affect existing VCs. This command
also defines the hold queue size of encapsulation PVCs.
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Configuring X.25 Routing
Restricting Map Usage
Command
Purpose
Router(config-if)#
x25 hold-queue packets
Defines the VC packet hold queue size.
Restricting Map Usage
An X.25 map can be restricted so that it will not be used to place calls or so that it will not be considered
when incoming calls are mapped. To restrict X.25 map usage, use the following commands in interface
configuration mode:
Command
Purpose
Router(config-if)# x25 map protocol address
[protocol2 address2 [...[protocol9
address9]]] x121-address no-incoming
Router(config-if)# x25 map protocol
[protocol2 address2 [...[protocol9
address9]]] x121-address no-outgoing
address
Restricts incoming calls from a map.
Restricts outgoing calls from a map.
Configuring X.25 Routing
•
•
•
•
Enabling X.25 Routing, page 59
Configuring an X.25 Route, page 59
Configuring a PVC Switched Between X.25 Interfaces, page 61
Configuring X.25 Switching Between PVCs and SVCs, page 62
Enabling X.25 Routing
You must enable X.25 routing to use switch VCs. To enable X.25 routing, use the following command in
global configuration mode:
Command
Purpose
Router(config)#
x25 routing [use-tcp-if-defs]
Enables X.25 routing. The use-tcp-if-defskeyword
is used by some routers that receive remote routed
calls from older versions of XOT; it might be
needed if the originating router cannot be updated
to a new software release. This keyword is
described in the "Configuring XOT to Use Interface
Default Flow Control Values, page 63" section.
Configuring an X.25 Route
To configure an X.25 route (thus adding the route to the X.25 routing table), use the following command in
global configuration mode:
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Configuring X.25 and LAPB
Configuring an X.25 Route
Command
Router(config)# x25 route [#position]
[selection-options] [modification-options]
disposition-options [xot-keepalive-options]
Purpose
Configures an X.25 route.
•
•
•
#position --Indicate the number of the entry in
the route table. For example, #9 indicates the
ninth entry from the top. The route table is
always searched sequentially from the top, and
the first match found will be used.
selection-options --Criteria to define the VCs
to which the route will apply. You can match
against zero to four of the following optional
selection elements:
◦ destination-pattern
◦ source source-pattern
◦ dest-ext nsap-destination-pattern
◦ cud user-data-pattern
modification -options --Modifications to the
source or destination address for address
translation. You can use neither, one, or both
of the following optional modification
elements to change the source or destination
address before forwarding the call to the
destination:
◦
◦
substitute-source rewrite-source
substitute-dest rewrite-destination
Note You must include a selection option or a
modification option in an x25 route
command.
•
disposition -options --Where the VC will be
forwarded or whether it will be cleared. You
are required to use one of the following
disposition elements:
◦
◦
◦
interface serial-interface--A route to a
specific serial-interface will send the VC
to an X.25 service on a synchronous serial
interface.
interface cmns-interface mac macaddress--A route to a broadcast interface
will send the VC to a CMNS partner
reachable on a broadcast medium at a
specified MAC address. The CMNS
interface can be an Ethernet, Token Ring,
or FDDI interface.
xot ip-address[ip2-address [...[ip6address]]] [xot-source interface]
A route to an xot destination (formerly called a
remote or tunneled configuration) will send the VC
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Configuring X.25 and LAPB
Configuring a PVC Switched Between X.25 Interfaces
Command
Purpose
to the XOT service for establishment of a TCP
connection across which the XOT VC packets will
travel. An xot disposition may specify alternate
destinations to try if a TCP connection cannot be
established for all preceding destinations.
•
•
◦
clear-- A route to a clear destination will
deny further service to the VC by shutting
down the connection.
xot-keepalive -options --You can use neither,
one, or both of the following optional xotkeepalive elements:
◦
xot-keepalive-period seconds
xot-keepalive-tries count
Configuring a PVC Switched Between X.25 Interfaces
You can configure an X.25 PVC in the X.25 switching software. As a result, DTE devices that require
permanent circuits can be connected to a router acting as an X.25 switch and have a properly functioning
connection. X.25 resets will be sent to indicate when the circuit comes up or goes down. Both interfaces
must define complementary locally switched PVCs.
•
•
Configuring a Locally Switched PVC, page 61
Ensuring the TCP sessions are Connected, page 61
Configuring a Locally Switched PVC
To configure a locally switched PVC, use the following command in interface configuration mod:
Command
Purpose
x25 pvc number1
interface type number pvc number2 [option]
Configures a locally switched PVC. The command
options are packetsize in out and windowsize in
out; they allow the flow control values of a PVC to
be defined if they differ from the interface defaults.
Router(config-if)#
Ensuring the TCP sessions are Connected
To ensure that TCP sessions remain connected in the absence of XOT traffic, use the following command
in global configuration mode. TCP keepalives also inform a router when an XOT SVC session is not active,
thus freeing router resources.
Command
Purpose
Router(config)#
service tcp-keepalives-in
Enables received keepalives for TCP sessions to
ensure timely detection of a connection failure.
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Configuring Additional X.25 Routing Features
Configuring X.25 Switching Between PVCs and SVCs
Command
Router(config)#
Purpose
service tcp-keepalives-out
Enables sent keepalives for TCP sessions to ensure
timely detection of a connection failure.
Configuring X.25 Switching Between PVCs and SVCs
In order for PVC to SVC switching to be configured between two serial interfaces, both interfaces must
already be configured for X.25. In addition, X.25 switching must be enabled using the x25 routing global
configuration command. The PVC interface must be a serial interface configured with X.25 encapsulation.
(The SVC interface may use X.25, XOT, or CMNS.) To configure X.25 switching between PVCs and
SVCs, use the following command in interface configuration mode. X.25 switching must already be
configured on the interace.
Command
Purpose
Router(config-if)# x25 pvc number1 svc
x121-address [flow-control-options] [callcontrol-options]
•
Configures PVC traffic to be forwarded to an SVC.
Displaying the Switched Information, page 62
Displaying the Switched Information
To display information about the switched PVC to SVC circuit, use the following command in EXEC
mode:
Purpose
Command
Router(config)#
]
show x25 vc
[lcn
Displays information about the active SVCs and
PVCs.
Configuring Additional X.25 Routing Features
•
•
•
•
•
Configuring X.25 Load Balancing, page 62
Configuring XOT to Use Interface Default Flow Control Values, page 63
Configuring Calling Address Interface-Based Insertion and Removal, page 63
Substituting Addresses in an X.25 Route, page 64
Configuring XOT Alternate Destinations, page 65
Configuring X.25 Load Balancing
Before enabling X.25 load balancing, you must activate the X.25 routing software and configure the
interfaces participating in the hunt group for X.25 encapsulation. To configure X.25 load balancing, use the
following commands beginning in global configuration mode:
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Configuring X.25 and LAPB
Verifying X.25 Load Balancing
SUMMARY STEPS
1. Router(config)# x25 routing
2. Router(config)# encapsulation x25
3. Router(config)# x25 hunt-group name {rotary | vc-count}
4. Router(config)# x25 route [#position] [selection-options] [modification-options] disposition-options
[xot-keepalive-options]
DETAILED STEPS
Command or Action
Purpose
Step 1 Router(config)# x25 routing
Activates X.25 routing software.
Step 2 Router(config)# encapsulation x25
Specifies X.25 encapsulation on each hunt group
interface.
Step 3 Router(config)# x25 hunt-group name {rotary | vc-count}
Creates the hunt group.
Step 4 Router(config)# x25 route [#position] [selection-options]
[modification-options] disposition-options [xot-keepaliveoptions]
Adds the hunt group to the routing table.
For examples of configuring X.25 load balancing, see the section "X.25 Load Balancing Examples, page
86" later in this chapter.
•
Verifying X.25 Load Balancing, page 63
Verifying X.25 Load Balancing
To verify X.25 load balancing, use the following command in EXEC mode:
Command
Router#
Purpose
show x25 hunt-group
Displays hunt groups and detailed interface
statistics and distribution methods.
Configuring XOT to Use Interface Default Flow Control Values
To configure this behavior, use the following command when enabling X.25 routing in global configuration
mode:
Command
Purpose
Router(config)#
x25 routing [tcp-use-if-defs]
Enables X.25 routing and optionally modifies XOT
source of unencoded flow control values.
Configuring Calling Address Interface-Based Insertion and Removal
To configure an input interface-based route statement into the X.121 address routing table, use either of the
following commands beginning in global configuration command mode:
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Configuring X.25 and LAPB
Verifying Interface-Based Calling Address Insertion
Command
Purpose
x25 route input-interface
interface source source-pattern substitutesource rewrite-source [continue]
Router(config)#
Inserts simplest input interface-based statement into
the routing table.
or
Router(config)# x25 route input-interface
interface disposition
•
Inserts an input interface-based route statement into
the routing table.
continue --(Optional) Performs address substitution
without address forwarding. That is, it executes the
address substitution instructions in each statement,
but then stops short of actual call switching, thereby
postponing the actual switching process until a
matching route statement with a disposition other
than continue is reached. The continue keyword is
most useful when you switch calls among four or
more routes. If your network has three or fewer
routes, the continue keyword will not save any
steps.
Verifying Interface-Based Calling Address Insertion, page 64
Verifying Interface-Based Calling Address Insertion
SUMMARY STEPS
1. To display the routes assigned by the x25 route command, use the show x25 routecommand in EXEC
mode. A sample display follows.
DETAILED STEPS
To display the routes assigned by the x25 route command, use the show x25 routecommand in EXEC mode. A
sample display follows.
Router# show x25 route
Example:
#
1
Match
dest ^01 input-int Serial0
Substitute
Sub-dest \1
Route to
Sub-source 00\0 Serial1
Substituting Addresses in an X.25 Route
When interconnecting two separate X.25 networks, you must sometimes provide address substitution for
routes. The x25 route command supports modification of X.25 source and destination addresses.
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Configuring DNS-Based X.25 Routing
Configuring XOT Alternate Destinations
Note
Address substitution is available for all applications of X.25 routes.
To modify addresses, use either or both of the following commands in global configuration mode:
Command
Purpose
x25 route [#position]
destination-pattern {source source-pattern
substitute-source rewrite-source} interface
interface number
Modifies the X.25 source address.
Router(config)#
|
x25 route [#position]
destination-pattern {source source-pattern |
substitute-dest rewrite-dest} interface interface
number
Modifies the X.25 destination address.
Router(config)#
Configuring XOT Alternate Destinations
Routes to XOT hosts can be configured with alternate destination hosts. On routing a call, XOT will try
each XOT destination host in sequence; if the TCP connection attempt fails, the next destination will be
tried. Up to six XOT destination addresses can be entered.
Note
Because of TCP timings, it can take up to 50 seconds to try an alternate route.
To configure an XOT route with alternate destinations (thus adding it to the X.25 routing table), use the
following command in global configuration mode (the sequence of alternate destination XOT host
addresses is added to the x25 routecommand using the xot keepalive-options):
Command
Purpose
x25 route [#position]
destination-pattern xot ip-address
Router(config)#
Configures an XOT route. Optionally defines
alternate XOT destination hosts.
[ip-address2
... [ip-address6]]
Configuring DNS-Based X.25 Routing
To configure DNS-based X.25 routing, use the following command in global configuration mode. This task
assumes that you already have XOT and DNS configured and enabled and that the route table in the DNS
server has been correctly organized.
Command
Purpose
Router(config)#
dns pattern
x25 route x121address xot
Configures XOT routing to search for IP addresses
in DNS.
For an example of configuring DNS-based X.25 routing, see the section DNS-Based X.25 Routing
Example, page 90 later in this chapter.
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Configuring X.25 and LAPB
Verifying DNS-Based X.25 Routing
•
•
Verifying DNS-Based X.25 Routing, page 66
Verifying DNS-Based X.25 Mnemonic Resolution, page 66
Verifying DNS-Based X.25 Routing
SUMMARY STEPS
1. To verify that the DNS-Based X.25 Routing feature is configured, use the show x25 route command in
EXEC mode:
2. If DNS-based X.25 routing is not functioning correctly, check that your DNS is configured properly and
operating correctly as follows:
DETAILED STEPS
Step 1
To verify that the DNS-Based X.25 Routing feature is configured, use the show x25 route command in EXEC mode:
Example:
Router# show x25 route
# Match
1 dest 444
2 dest 555
Step 2
Substitute
Route to
xot dns \0
xot dns \0
If DNS-based X.25 routing is not functioning correctly, check that your DNS is configured properly and operating
correctly as follows:
•
•
Use the show hosts command to display temporary entries cached by DNS at the router.
Use debug x25 events and debug domain commands to display current data flow. See the Cisco IOS Debug
Command Reference for more information.
Verifying DNS-Based X.25 Mnemonic Resolution
SUMMARY STEPS
1. To verify DNS-based X.25 mnemonic resolution, use the show hosts command in EXEC mode. All
permanent (perm) entries of type X.121 should be removed from the route table for DNS-based X.25
routing to work.
DETAILED STEPS
To verify DNS-based X.25 mnemonic resolution, use the show hosts command in EXEC mode. All permanent (perm)
entries of type X.121 should be removed from the route table for DNS-based X.25 routing to work.
In the following example, the mnemonic "destination_host" is showing itself to be a permanent entry:
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Configuring X.25 over Frame Relay (Annex G)
Verifying DNS-Based X.25 Mnemonic Resolution
Example:
Router# show hosts
Default domain is home.com
Name/address lookup uses domain service
Name servers are 10.1.1.40
Host
destination_host
Flags
Age Type
(perm, OK) 1 X.121
Address(es)
222
Configuring X.25 over Frame Relay (Annex G)
To configure an Annex G connection (assuming you have already configured a Frame Relay connection on
your router), use the following commands beginning in global configuration mode:
SUMMARY STEPS
1.
2.
3.
4.
5.
6.
7.
Router(config)# x25 profile name
Router(config)# interface type number
Router(config-if)# encapsulation frame-relay
Router(config-if)# frame-relay interface-dlci
Router(config-fr-dlci)# x25-profile name
Router(config)# x25 routing
Router(config)# x25 route number interface serial-interface dlci number
DETAILED STEPS
Purpose
Command or Action
Step 1 Router(config)# x25 profile name
Creates the X.25 profile.
Step 2 Router(config)# interface type number
Configures an interface.
Step 3 Router(config-if)# encapsulation frame-relay
Activates Frame Relay encapsulation on each interface that will be
using Annex G connections.
Step 4 Router(config-if)# frame-relay interface-dlci
Configures the Frame Relay DLCI.
Step 5 Router(config-fr-dlci)# x25-profile name
Assigns the named X.25 profile to the DLCI.
Step 6 Router(config)# x25 routing
(Optional) Enables X.25 routing of outgoing calls.
Step 7 Router(config)# x25 route number interface
serial-interface dlci number
(Optional) Assigns an X.25 route for the DLCI on that interface.
Required if you want the router to accept switched calls, as well as
originating them.
Configuring CMNS Routing
•
•
Enabling CMNS on an Interface, page 68
Configuring a Route to a CMNS Host, page 68
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Configuring Priority Queueing or Custom Queueing for X.25
Enabling CMNS on an Interface
Enabling CMNS on an Interface
To enable CMNS on a nonserial interface, use the following command in interface configuration mode:
Command
Router(config-if)#
Purpose
cmns enable
Enables CMNS.
Configuring a Route to a CMNS Host
Once CMNS is enabled on a nonserial interface, the router can forward calls over that medium by
configuring x25 route commands that define the MAC address of each CMNS host that can be reached. To
define routes to CMNS hosts, use the following command--plus pattern and character match options for the
x25 route command--in interface configuration mode:
Command
Router(config)# x25 route patterncharacter match options interface cmns-
Purpose
Defines route to CMNS host.
interface mac mac-address
Configuring Priority Queueing or Custom Queueing for X.25
To configure priority queueing and custom queueing for X.25, perform the following steps:
SUMMARY STEPS
1. Perform the standard priority and custom queueing tasks except the task of assigning a priority or
custom group to the interface, as described in the chapters "Configuring Priority Queueing" and
"Configuring Custom Queueing" in the Cisco IOS Quality of Service Solutions Configuration Guide .
2. Perform the standard X.25 encapsulation tasks, as specified in the section "Configuring an X.25
Datagram Transport, page 53" earlier in this chapter.
3. Assign either a priority group or a custom queue to the interface, as described in the chapters
"Configuring Priority Queueing" and "Configuring Custom Queueing" in the Cisco IOS Quality of
Service Solutions Configuration Guide .
DETAILED STEPS
Step 1
Step 2
Step 3
Perform the standard priority and custom queueing tasks except the task of assigning a priority or custom group to the
interface, as described in the chapters "Configuring Priority Queueing" and "Configuring Custom Queueing" in the
Cisco IOS Quality of Service Solutions Configuration Guide .
Perform the standard X.25 encapsulation tasks, as specified in the section "Configuring an X.25 Datagram Transport,
page 53" earlier in this chapter.
Assign either a priority group or a custom queue to the interface, as described in the chapters "Configuring Priority
Queueing" and "Configuring Custom Queueing" in the Cisco IOS Quality of Service Solutions Configuration Guide .
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Configuring X.25 Closed User Groups
Configuring X.25 CUG Service Access and Properties
Configuring X.25 Closed User Groups
•
•
•
•
•
•
•
•
Configuring X.25 CUG Service Access and Properties, page 69
Configuring a POP with No CUG Access, page 69
Configuring a POP with Access Restricted to One CUG, page 70
Configuring a POP with Multiple CUGs and No Public Access, page 70
Configuring a POP with Multiple CUGs and Public Access, page 71
Configuring CUG Selection Facility Suppression, page 72
Verifying X.25 CUG Service, page 73
Troubleshooting Tips for X.25 CUG Service, page 73
Configuring X.25 CUG Service Access and Properties
To configure X.25 CUG service, access, and properties, use the following commands beginning in global
configuration mode:
SUMMARY STEPS
1. Router(config)# interface number
2. Router(config-if)# encapsulation x25 dce
3. Router(config-if)# x25 subscribe cug-service [incoming-access | outgoing-access]
4. Router(config-if)# x25 subscribe local-cug number network-cug number [no-incoming | no-outgoing
| preferential]
DETAILED STEPS
Purpose
Command or Action
Step 1 Router(config)# interface number
Selects the interface to be configured.
Step 2 Router(config-if)# encapsulation x25 dce
Enables X.25 DCE network operation.
Step 3 Router(config-if)# x25 subscribe cug-service [incomingaccess | outgoing-access]
Enables and controls standard CUG behavior on an X.25
DCE interface.
Step 4 Router(config-if)# x25 subscribe local-cug number network- Maps the desired local CUG number to its corresponding
network CUG.
cug number [no-incoming | no-outgoing | preferential]
Configuring a POP with No CUG Access
To configure a POP with no CUG access, use the following commands beginning in global configuration
mode:
SUMMARY STEPS
1. Router(config)# interface number
2. Router(config-if)# encapsulation x25 dce
3. Router(config-if)# x25 subscribe cug-service incoming-access outgoing-access
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Configuring X.25 and LAPB
Configuring a POP with Access Restricted to One CUG
DETAILED STEPS
Command or Action
Purpose
Step 1 Router(config)# interface number
Selects the interface to be configured.
Step 2 Router(config-if)# encapsulation x25 dce
Enables X.25 DCE network operation.
Step 3 Router(config-if)# x25 subscribe cug-service incoming- Permits incoming and outgoing CUG access on an X.25 DCE
interface.
access outgoing-access
Configuring a POP with Access Restricted to One CUG
To configure a POP with access restricted to one CUG, use the following commands beginning in global
configuration mode:
SUMMARY STEPS
1. Router(config)# interface number
2. Router(config-if)# encapsulation x25 dce
3. Router(config-if)# x25 subscribe cug-service
4. Router(config-if)# x25 subscribe local-cug number network-cug number [no-incoming | no-outgoing
| preferential]
DETAILED STEPS
Command or Action
Purpose
Step 1 Router(config)# interface number
Selects the interface to be configured.
Step 2 Router(config-if)# encapsulation x25 dce
Enables X.25 DCE network operation.
Step 3 Router(config-if)# x25 subscribe cug-service
Sets default behavior on an X.25 DCE interface.
Step 4 Router(config-if)# x25 subscribe local-cug number
network-cug number [no-incoming | no-outgoing |
preferential]
Maps the desired local CUG number to its corresponding
network CUG.
Configuring a POP with Multiple CUGs and No Public Access
To configure a POP with multiple CUGs and no public access, use the following commands beginning in
global configuration mode:
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Configuring X.25 and LAPB
Configuring a POP with Multiple CUGs and Public Access
SUMMARY STEPS
1. Router(config)# interface number
2. Router(config-if)# encapsulation x25 dce
3. Router(config-if)# x25 subscribe cug-service
4. Router(config-if)# x25 subscribe local-cug number network-cug number [no-incoming | no-outgoing
| preferential]
5. Router(config-if)# x25 subscribe local-cug number network-cug number [no-incoming | no-outgoing
| preferential]
DETAILED STEPS
Command or Action
Purpose
Step 1 Router(config)# interface number
Selects the interface to be configured.
Step 2 Router(config-if)# encapsulation x25 dce
Enables X.25 DCE network operation.
Step 3 Router(config-if)# x25 subscribe cug-service
Sets default CUG behavior on an X.25 DCE
interface.
Step 4 Router(config-if)# x25 subscribe local-cug number network-cug Maps the desired local CUG number to its
corresponding network CUG.
number [no-incoming | no-outgoing | preferential]
Step 5 Router(config-if)# x25 subscribe local-cug number network-cug Configures another CUG interface.
number [no-incoming | no-outgoing | preferential]
Configuring a POP with Multiple CUGs and Public Access
To configure a POP with multiple CUGs and public access, use the following commands beginning in
global configuration mode:
SUMMARY STEPS
1. Router(config)# interface number
2. Router(config-if)# encapsulation x25 dce
3. Router(config-if)# x25 subscribe cug-service incoming-access outgoing-access
4. Router(config-if)# x25 subscribe local-cug number network-cug number [no-incoming | no-outgoing
| preferential]
5. Router(config-if)# x25 subscribe local-cug number network-cug number [no-incoming | no-outgoing
| preferential]
DETAILED STEPS
Command or Action
Purpose
Step 1 Router(config)# interface number
Selects the interface to be configured.
Step 2 Router(config-if)# encapsulation x25 dce
Enables X.25 DCE network operation.
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Configuring X.25 and LAPB
Configuring CUG Selection Facility Suppression
Command or Action
Purpose
Step 3 Router(config-if)# x25 subscribe cug-service incoming-access
outgoing-access
Permits incoming and outgoing CUG access on an
X.25 DCE interface.
Step 4 Router(config-if)# x25 subscribe local-cug number network-cug
number [no-incoming | no-outgoing | preferential]
Maps the desired local CUG number to its
corresponding network CUG.
Step 5 Router(config-if)# x25 subscribe local-cug number network-cug
number [no-incoming | no-outgoing | preferential]
Configures another CUG interface.
Configuring CUG Selection Facility Suppression
•
•
Configuring CUG Selection Facility Suppression on an Interface, page 72
Configuring CUG Selection Facility Suppression on an X.25 Profile, page 72
Configuring CUG Selection Facility Suppression on an Interface
To configure X.25 CUG selection facility suppression on an interface, use the following commands
beginning in global configuration mode:
SUMMARY STEPS
1. Router(config)# interface type number
2. Router(config-if)# encapsulation x25 dce
3. Router(config-if)# x25 subscribe cug-service [incoming-access | outgoing-access] [suppress
preferential | suppress all
DETAILED STEPS
Command or Action
Purpose
Step 1 Router(config)# interface type number
Configures an interface type and enters interface configuration
mode.
Step 2 Router(config-if)# encapsulation x25 dce
Specifies that a serial interface will operate as an X.25 DCE
device.
Step 3 Router(config-if)# x25 subscribe cug-service
[incoming-access | outgoing-access] [suppress
preferential | suppress all
Enables and controls standard CUG behavior on an X.25 DCE
interface.
Configuring CUG Selection Facility Suppression on an X.25 Profile
To configure X.25 CUG selection facility suppression on an X.25 profile, use the following commands
beginning in global configuration mode:
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Configuring DDN or BFE X.25
Verifying X.25 CUG Service
SUMMARY STEPS
1. Router(config)# x25 profile name dce
2. Router(config-x25)# x25 subscribe cug-service [incoming-access | outgoing-access] [suppress
preferential | suppress all
DETAILED STEPS
Command or Action
Purpose
Step 1 Router(config)# x25 profile name dce
Configures an X.25 profile and specifies a DCE station
type.
Step 2 Router(config-x25)# x25 subscribe cug-service [incomingaccess | outgoing-access] [suppress preferential | suppress
all
Enables and controls standard CUG behavior on an X.25
DCE interface.
Verifying X.25 CUG Service
To show current settings of the X.25 CUGs feature, use the show x25 cug (either keyword local-cug or
network-cug must be designated) command in EXEC mode. In the following example local CUGs 100,
200, 300, and 5000 are shown mapped to their related network CUGs 11, 22, 33, and 55, respectively, all
with incoming and outgoing public access, and with network CUG 55 being set as the preferential:
Router# show x25 cug local-cug
X.25 Serial0, 4 CUGs subscribed with incoming and outgoing public access
local-cug 100 <-> network-cug 11
local-cug 200 <-> network-cug 22
local-cug 300 <-> network-cug 33
local-cug 5000 <-> network-cug 55, preferential
Troubleshooting Tips for X.25 CUG Service
You can use debug x25 events command to verify if and when CUG calls are being made and how the
CUGs are behaving. The following example shows messages concerning a rejection of a call by a DCE
because CUG 40 is not configured at the DCE interface, either by design or by administrative mistake:
Router# debug x25 events
00:48:33:Serial1:X.25 I R1 Call (14) 8 lci 1024
00:48:33: From (3):111 To (3):444
00:48:33: Facilities:(2)
00:48:33:
Closed User Group (basic):40
00:48:33: Call User Data (4):0x01000000 (pad)
00:48:33:X.25 Incoming Call packet, Closed User Group (CUG) protection, selected network
CUG not subscribed
00:48:33:Serial1:X.25 O R1 Clear (5) 8 lci 1024
00:48:33: Cause 11, Diag 65 (Access barred/Facility code not allowed)
Configuring DDN or BFE X.25
•
•
•
Enabling DDN X.25, page 74
Defining IP Precedence Handling, page 74
Configuring Blacker Front End X.25, page 74
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Configuring X.25 Remote Failure Detection
Enabling DDN X.25
Enabling DDN X.25
Both DCE and DTE operation causes the Cisco IOS software to specify the Standard Service facility in the
Call Request packet, which notifies the PSNs to use Standard Service. To enable DDN X.25, use one of the
following commands in interface configuration mode, as appropriate for your network:
Command
Purpose
Router(config-if)#
encapsulation x25 ddn
Router(config-if)#
encapsulation x25 dce ddn
Sets DDN X.25 DTE operation.
Sets DDN X.25 DCE operation.
Defining IP Precedence Handling
By default, the DDN X.25 software opens one VC for all types of service values. To enable the precedencesensitivity feature, use the following command in interface configuration mode:
Command
Router(config-if)#
Purpose
x25 ip-precedence
Allows a new VC based on the type of service
(TOS) field.
Configuring Blacker Front End X.25
To set BFE encapsulation on the router attached to a BFE device, use the following command in interface
configuration mode:
Purpose
Command
Router(config-if)#
encapsulation x25 bfe
Sets BFE encapsulation on the router attached to a
BFE device.
Configuring X.25 Remote Failure Detection
•
•
•
X.25 Remote Failure Detection with IP Static Routes, page 74
X.25 Remote Failure Detection and the Backup Interface, page 75
Verifying X.25 Remote Failure Detection, page 77
X.25 Remote Failure Detection with IP Static Routes
To configure X.25 remote failure detection with IP static routes, use the following commands beginning in
global configuration mode:
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Configuring X.25 and LAPB
X.25 Remote Failure Detection and the Backup Interface
SUMMARY STEPS
1. Router(config)# interface number
2. Router(config-if)# encapsulation x25
3. Router(config-if)# x25 address x121-address
4. Router(config-if)# interface subinterface number point-to-point
5. Router(config-subif)# ip address address mask
6. Router(config-subif)# x25 map ipaddress x121address
7. Router(config-subif)# x25 retry interval seconds attempts count
8. Router(config)# ip route address mask serial subinterface number weight
9. Router(config)# ip route address mask serial nextsubinterface number weight
DETAILED STEPS
Command or Action
Purpose
Step 1 Router(config)# interface number
Enters specified interface configuration mode.
Step 2 Router(config-if)# encapsulation x25
Enables X.25 encapsulation on the interface.
Step 3 Router(config-if)# x25 address x121-address
Sets X.121 address of the network interface.
Step 4 Router(config-if)# interface subinterface number
point-to-point
Enters specified subinterface and enables point-to-point for it.
Step 5 Router(config-subif)# ip address address mask
Creates IP address and mask for the subinterface.
Step 6 Router(config-subif)# x25 map ipaddress x121address Maps IP address to an X.121 address.
Step 7 Router(config-subif)# x25 retry interval seconds
attempts count
Enables the X.25 retry option on the subinterface.
Step 8 Router(config)# ip route address mask serial
subinterface number weight
Configures static route from point-to-point interface specified to
a destination.
Step 9 Router(config)# ip route address mask serial
nextsubinterface number weight
Configures static route from next point-to-point interface
specified for the same destination.
X.25 Remote Failure Detection and the Backup Interface
To configure X.25 remote failure detection and create a backup interface, use the following commands
beginning in global configuration mode. Note that IP static routes need not be configured because this
backup route is being only configured as a secondary route.
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Configuring X.25 and LAPB
X.25 Remote Failure Detection and the Backup Interface
SUMMARY STEPS
1. Router(config)# interface number
2. Router(config-if)# encapsulation x25
3. Router(config-if)# x25 address x121-address
4. Router(config)# interface subinterface number point-to-point
5. Router(config-subif)# ip address address mask
6. Router(config-subif)# x25 map ipaddress x121address
7. Router(config-subif)# x25 retry interval seconds attempts count
8. Router(config-subif)# backup interface serial number
9. Router(config)# interface number
10. Router(config-if)# encapsulation x25
11. Router(config-if)# x25 address x121-address
12. Router(config-if)# ip address address mask
13. Router(config-if)# x25 map ipaddress x121address
DETAILED STEPS
Command or Action
Purpose
Step 1 Router(config)# interface number
Enters specified interface configuration mode.
Step 2 Router(config-if)# encapsulation x25
Enables X.25 encapsulation on the interface.
Step 3 Router(config-if)# x25 address x121-address
Sets X.121 address of the network interface.
Step 4 Router(config)# interface subinterface number point- Enters specified subinterface and configures point-to-point for it.
to-point
Step 5 Router(config-subif)# ip address address mask
Creates IP address and mask for the subinterface.
Step 6 Router(config-subif)# x25 map ipaddress
x121address
Maps IP address to an X.121 address.
Step 7 Router(config-subif)# x25 retry interval seconds
attempts count
Enables the X.25 retry option on the subinterface.
Step 8 Router(config-subif)# backup interface serial
number
Configures specified interface as the backup.
Step 9 Router(config)# interface number
Enters specified interface configuration mode to configure the
backup.
Step 10 Router(config-if)# encapsulation x25
Enables X.25 encapsulation on the interface.
Step 11 Router(config-if)# x25 address x121-address
Sets X.121 address of the network interface.
Step 12 Router(config-if)# ip address address mask
Creates IP address and mask for the subinterface.
Step 13 Router(config-if)# x25 map ipaddress x121address
Maps IP address to an X.121 address.
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Creating X.29 Access Lists
Verifying X.25 Remote Failure Detection
Verifying X.25 Remote Failure Detection
SUMMARY STEPS
1. To verify X.25 remote failure detection, use the show interfaces serialcommand on the interface with
the x25 retry command configured. The last line in the following output shows the X.25 retry
mechanism currently in action on subinterface 1.1, which is currently down--as indicated by the "(retry
in progress)" statement--and which has "tried" one out of its possible 100 retry attempts.
2. To verify which route is currently in use by IP, use the show ip route command.
3. The debug x25 events command can be also activated, so that you can see a call being attempted by the
X.25 retry mechanism every configured interval.
DETAILED STEPS
Step 1
To verify X.25 remote failure detection, use the show interfaces serialcommand on the interface with the x25 retry
command configured. The last line in the following output shows the X.25 retry mechanism currently in action on
subinterface 1.1, which is currently down--as indicated by the "(retry in progress)" statement--and which has "tried"
one out of its possible 100 retry attempts.
Example:
Router# show interfaces serial1
Serial1 is up, line protocol is up
Hardware is QUICC Serial
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation X25, loopback not set
X.25 DTE, address 11111, state R1, modulo 8, timer 0
Defaults:idle VC timeout 0
cisco encapsulation
input/output window sizes 2/2, packet sizes 128/128
Timers:T20 180, T21 200, T22 180, T23 180
Channels:Incoming-only none, Two-way 1-1024, Outgoing-only none
RESTARTs 2/0 CALLs 0+0/0+0/0+0 DIAGs 0/0
Interface Serial1.1:retry-interval 5, attempts 100, tried 1 (retry in progress)
Step 2
To verify which route is currently in use by IP, use the show ip route command.
Step 3
The debug x25 events command can be also activated, so that you can see a call being attempted by the X.25 retry
mechanism every configured interval.
Creating X.29 Access Lists
•
•
Creating an X.29 Access List, page 77
Applying an Access List to a Virtual Terminal Line, page 78
Creating an X.29 Access List
To specify the access conditions, use the following command beginning in global configuration mode:
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Creating an X.29 Profile Script
Applying an Access List to a Virtual Terminal Line
Command
Router(config)#
number {deny |
Purpose
x29 access-list access-listpermit} x121-address
Restricts incoming and outgoing connections
between a particular vty (into a Cisco access server)
and the addresses in an access list.
Applying an Access List to a Virtual Terminal Line
To apply an access list to a virtual line, use the following command in line configuration mode:
Command
Router(config)#
Purpose
access-class access-list-
number in
Restricts incoming and outgoing connections
between a particular vty (into a Cisco access server)
and the addresses in an access list.
Creating an X.29 Profile Script
You can create an X.29 profile script for use by the translate command. When an X.25 connection is
established, the protocol translator then acts as if an X.29 Set Parameter packet had been sent that contained
the parameters and values set by this command.
To create an X.29 profile script, use the following command beginning in global configuration mode:
Purpose
Command
Router(config)#
name} parameter
x29 profile {default |
: value [parameter : value]
Creates an X.29 profile script.
For an example of a profile script, see the section X.29 Profile Script Example, page 102 at the end of this
chapter.
Monitoring and Maintaining LAPB and X.25
To monitor and maintain X.25 and LAPB, use any of the following commands in EXEC mode:
Command
Purpose
clear x25 {serial number | cmnsinterface mac-address} [vc-number]
Router#
clear xot remote ip-address port local
ip-address port
Clears an SVC, restarts an X.25 or CMNS service,
or resets a PVC.
Clears an XOT SVC or resets an XOT PVC.
Router#
Displays CMNS information.
Router#
]
show cmns [type
Router#
show interfaces serial number
number
Displays operation statistics for an interface.
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Configuring X.25 and LAPB
X.25 and LAPB Configuration Examples
Command
Router#
Purpose
Displays CMNS connections over LLC2.
show llc2
show x25 interface [serial number
cmns-interface mac mac-address]
Router#
|
Displays information about VCs on an X.25
interface (a serial interface) or a CMNS interface
(an Ethernet, Token Ring, or FDDI interface).
Displays the protocol-to-X.121 address map.
Router#
show x25 map
Router#
show x25 remote-red
Displays the one-to-one mapping of the IP
addresses of the host and the IP addresses of the
remote BFE device.
Router#
show x25 route
Displays routes assigned by the x25 route
command.
Router#
show x25 services
Router#
show x25 vc [lcn]
Router# show x25 xot [local ip-address
[port port]] [remote ip-address [port
port]]
Displays information about X.25 services.
Displays details of active VCs.
Displays information for all XOT VCs or,
optionally, for VCs that match a specified set of
criteria.
X.25 and LAPB Configuration Examples
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Typical LAPB Configuration Example, page 80
Transparent Bridging for Multiprotocol LAPB Encapsulation Example, page 80
Typical X.25 Configuration Example, page 80
VC Ranges Example, page 82
X.25 Failover Example, page 82
PVC Switching on the Same Router Example, page 82
X.25 Route Address Pattern Matching Example, page 82
X.25 Routing Examples, page 83
PVC Used to Exchange IP Traffic Example, page 84
Point-to-Point Subinterface Configuration Example, page 84
Simple Switching of a PVC over XOT Example, page 85
PVC Switching over XOT Example, page 85
X.25 Load Balancing Examples, page 86
X.25 Switching Between PVCs and SVCs Example, page 87
Inserting and Removing X.121 Addresses As Calls Are Routed Example, page 88
Forwarding Calls Using the continue Keyword Example, page 88
DNS-Based X.25 Routing Example, page 90
X.25overFrameRelayAnnexGExample, page 90
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Typical LAPB Configuration Example
X.25 and LAPB Configuration Examples
•
•
•
•
•
•
•
•
•
•
•
•
•
•
CMNS Switching Example, page 91
CMNS Switching over a PDN Example, page 92
CMNS Switched over Leased Lines Example, page 93
Configuring Local Acknowledgment Example, page 94
Setting Asymmetrical Window and Packet Sizes Flow Control Never Example, page 94
Configuring Flow Control Always Example, page 95
X.25 CUGs Examples, page 96
DDN X.25 Configuration Example, page 98
Blacker Front End Example, page 99
X.25 Ping Support over Multiple Lines Example, page 99
Booting from a Network Server over X.25 Example, page 100
X.25 Remote Failure Detection Examples, page 100
X.29 Access List Example, page 101
X.29 Profile Script Example, page 102
Typical LAPB Configuration Example
In the following example, the frame size (N1), window size (k), and maximum retransmission (N2)
parameters retain their default values. The encapsulation interface configuration command sets DCE
operation to carry a single protocol, IP by default. The lapb t1interface configuration command sets the
retransmission timer to 4,000 milliseconds (4 seconds) for a link with a long delay or slow connecting DTE
device.
interface serial 3
encapsulation lapb dce
lapb t1 4000
Transparent Bridging for Multiprotocol LAPB Encapsulation Example
The following example configures transparent bridging for multiprotocol LAPB encapsulation:
no ip routing
!
interface Ethernet 1
no ip address
no mop enabled
bridge-group 1
!
interface serial 0
no ip address
encapsulation lapb multi
bridge-group 1
!
bridge 1 protocol ieee
Typical X.25 Configuration Example
The following example shows the complete configuration for a serial interface connected to a commercial
X.25 PDN for routing the IP protocol. The IP subnetwork address 172.25.9.0 has been assigned for the X.
25 network.
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Configuring X.25 and LAPB
X.25 and LAPB Configuration Examples
Note
When you are routing IP over X.25, you must treat the X.25 network as a single IP network or subnetwork.
Map entries for routers that have addresses on subnetworks other than the one on which the IP address of
the interface is stored are ignored by the routing software. Additionally, all routers using the subnet number
must have map entries for all other routers. Moreover, using the broadcast option with dynamic routing can
result in significantly larger traffic loads, requiring a larger hold queue, larger window sizes, or multiple
VCs.
interface serial 2
ip address 172.25.9.1 255.255.255.0
!
encapsulation X25
!
! The "bandwidth" command is not part of the X.25
! configuration; it is especially important to understand that it does not
! have any connection with the X.25 entity of the same name.
! "bandwidth" commands are used by IP routing processes (currently only IGRP)
! to determine which lines are the best choices for traffic.
! Since the default is 1544 Kbaud, and X.25 service at that rate is not generally
! available, most X.25 interfaces that are being used with IGRP in a
! real environment will have "bandwidth" settings.
!
! This is a 9.6 Kbaud line:
!
bandwidth 10
! You must specify an X.121 address to be assigned to the X.25 interface by the PDN.
!
x25 address 31370054065
!
! The following Level 3 parameters have been set to match the network.
! You generally need to change some Level 3 parameters, most often
! those listed below. You might not need to change any Level 2
! parameters, however.
!
x25 htc 32
!
! These Level 3 parameters are default flow control values; they need to
! match the PDN defaults. The values used by an SVC are negotiable on a per-call basis:
!
x25 win 7
x25 wout 7
x25 ips 512
x25 ops 512
!
!
! The following commands configure the default behavior for our encapsulation
! SVCs
!
x25 idle 5
x25 nvc 2
!
! The following commands configure the X.25 map. If you want to exchange
! routing updates with any of the routers, they would need
! "broadcast" flags.
! If the X.25 network is the only path to the routers, static routes are
! generally used to save on packet charges. If there is a redundant
! path, it might be desirable to run a dynamic routing protocol.
!
x25 map IP 172.25.9.3 31370019134 ACCEPT-REVERSE
! ACCEPT-REVERSE allows collect calls
x25 map IP 172.25.9.2 31370053087
!
! If the PDN cannot handle fast back-to-back frames, use the
!"transmitter-delay" command to slow down the interface.
!
transmitter-delay 1000
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VC Ranges Example
X.25 and LAPB Configuration Examples
VC Ranges Example
The following example sets the VC ranges of 5 to 20 for incoming calls only (from the DCE to the DTE)
and 25 to 1024 for either incoming or outgoing calls. It also specifies that no VCs are reserved for outgoing
calls (from the DTE to the DCE). Up to four permanent VCs can be defined on VCs 1 through 4.
x25 lic 5
x25 hic 20
x25 ltc 25
X.25 Failover Example
In the following example, X.25 failover is configured on a network that is also configured for Annex G. If
data-link connection identifier (DLCI) 13 or DLCI 14 on serial interface 1/0 goes down, dialer interface 1
will serve as the secondary interface. After DLCI 13 or 14 comes back up and remains up for 20 seconds,
dialer interface 1 will reset, sending all calls back to the primary interface.
interface serial1/0
encapsulation frame-relay
frame-relay interface-dlci 13
x25-profile frame1
exit
frame-relay interface-dlci 14
x25-profile frame1
exit
!
interface dialer1
encapsulation x25
exit
x25 route ^1234 interface serial1/0 dlci 13
x25 route ^1234 interface serial1/0 dlci 14
x25 route ^1234 interface dialer1
!
x25 profile frame1 dte
x25 fail-over 20 interface dialer1
exit
!
PVC Switching on the Same Router Example
In the following example, a PVC is connected between two serial interfaces on the same router. In this type
of interconnection configuration, the destination interface must be specified along with the PVC number on
that interface. To make a working PVC connection, two commands must be specified, each pointing to the
other.
interface serial 0
encapsulation x25
x25 ltc 5
x25 pvc 1 interface serial 1 pvc 4
!
interface serial 1
encapsulation x25
x25 ltc 5
x25 pvc 4 interface serial 0 pvc 1
X.25 Route Address Pattern Matching Example
The following example shows how to route X.25 calls with addresses whose first four Data Network
Identification Code (DNIC) digits are 1111 to interface serial 3. This example also shows how to change
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X.25 Routing Examples
X.25 and LAPB Configuration Examples
the DNIC field to 2222 in the addresses presented to equipment connected to that interface. The \1 in the
rewrite pattern indicates the portion of the original address matched by the digits following the 1111 DNIC.
x25 route ^1111(.*) substitute-dest 2222\1 interface serial 3
The figure below shows a more contrived command intended to illustrate the power of the rewriting
scheme.
Figure 9
X.25 Route Address Pattern Matching Example
The command in the figure above causes all X.25 calls with 14-digit called addresses to be routed through
interface serial 0. The incoming DNIC field is moved to the end of the address. The fifth, sixth, ninth, and
tenth digits are deleted, and the thirteenth and fourteenth are moved before the eleventh and twelfth.
X.25 Routing Examples
The following examples illustrate how to enable the X.25 switch service and how to configure a router on a
Tymnet/PAD switch to accept and forward calls.
The first example shows enabling X.25 switching and entering routes in the X.25 routing table:
! Enable X.25 forwarding
x25 routing
! Enter routes into the table. Without a positional parameter, entries
! are appended to the end of the table
x25 route ^100$ interface serial 0
x25 route 100 cud ^pad$ interface serial 2
x25 route 100 interface serial 1
x25 route ^3306 interface serial 3
x25 route .* ip 10.2.0.2
The routing table forwards calls for X.121 address 100 out interface serial 0. Otherwise, calls are forwarded
onto serial 1 if the X.121 address contains 100 anywhere within it and contains no call user data (CUD), or
if the CUD is not the string "pad." If the X.121 address contains the digits 100 and the CUD is the string
"pad," the call is forwarded onto serial 2. All X.121 addresses that do not match the first three routes are
checked for a DNIC of 3306 as the first four digits. If they do match, they are forwarded over serial 3. All
other X.121 addresses will match the fifth entry, which is a match-all pattern and will have a TCP
connection established to the IP address 10.2.0.2. The router at 10.2.0.2 will then handle the call according
to its configuration.
This second example configures a router that sits on a Tymnet/PAD switch to accept calls and have them
forwarded to a DEC VAX system. This feature permits running an X.25 network over a generalized
existing IP network, thereby making another physical line for one protocol unnecessary. The router
positioned next to the DEC VAX system is configured with X.25 routes, as follows:
x25 route vax-x121-address interface serial 0
x25 route .* ip cisco-on-tymnet-ipaddress
These commands route all calls to the DEC VAX X.121 address out to serial 0, where the VAX is
connected running PSI. All other X.121 addresses are forwarded to the "cisco-on-tymnet" address through
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PVC Used to Exchange IP Traffic Example
X.25 and LAPB Configuration Examples
its IP address. As a result, all outgoing calls from the VAX are sent to "cisco-on-tymnet" for further
processing.
On the router named "cisco-on-tymnet", you enter these commands:
x25 route vax-x121-address ip cisco-on-vax
x25 route .* interface serial 0
These commands force all calls with the VAX X.121 address to be sent to the router that has the VAX
connected to it. All other calls with X.121 addresses are forwarded out to Tymnet. If Tymnet can route
them, a Call Accepted packet is returned, and everything proceeds normally. If Tymnet cannot handle the
calls, it clears each call and the Clear Request packet is forwarded back toward the VAX.
PVC Used to Exchange IP Traffic Example
The following example, illustrated in the figure below, demonstrates how to use the PVC to exchange IP
traffic between router X and router Y.
Figure 10
Establishing an IP Encapsulation PVC Through an X.25 Network
Configuration for Router X
interface serial 2
ip address 172.20.1.3 255.255.255.0
x25 pvc 4 ip 172.20.1.4
Configuration for Router Y
interface serial 3
ip address 172.20.1.4 255.255.255.0
x25 pvc 3 ip 172.20.1.3
In this example, the PDN has established a PVC through its network, connecting PVC number 3 of access
point A to PVC number 4 of access point B. On router X, a connection is established between router X and
router Y’s IP address, 172.20.1.4. On router Y, a connection is established between router Y and router X’s
IP address, 172.20.1.3.
Point-to-Point Subinterface Configuration Example
The following example creates a point-to-point subinterface, maps IP and AppleTalk to a remote host, and
creates an encapsulating PVC for DECnet to the same remote host, identified by the X.121 address in the
commands:
interface Serial0.1 point-to-point
x25 map ip 172.20.170.90 170090 broadcast
x25 map appletalk 4.50 170090 broadcast
x25 pvc 1 decnet 1.2 170090 broadcast
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Simple Switching of a PVC over XOT Example
X.25 and LAPB Configuration Examples
Simple Switching of a PVC over XOT Example
In the following simple example, a connection is established between two PVCs across a LAN. Because the
connection is remote (across the LAN), the XOT service is used. This example establishes a PVC between
router X, serial 0, PVC 1 and router Y, serial 1, PVC 2. Keepalives are enabled to maintain connection
notification. The figure below provides a visual representation of the configuration.
Figure 11
X.25 PVC Connection
Configuration for Router X
service tcp-keepalives-in
service tcp-keepalives-out
interface serial 0
x25 pvc 1 xot 172.20.1.2 interface serial 1 pvc 2
Configuration for Router Y
service tcp-keepalives-in
service tcp-keepalives-out
interface serial 1
x25 pvc 2 xot 172.20.1.1 interface serial 0 pvc 1
PVC Switching over XOT Example
In the more complex example shown in the figure below, the connection between points A and B is
switched, and the connections between point C and points A and B are made using XOT. Keepalives are
enabled to maintain connection notification.
Figure 12
PVC Switching over XOT
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X.25 Load Balancing Examples
X.25 Load Balancing Using VC-Count Distribution Method Example
Configuration for Router X
service tcp-keepalives-in
service tcp-keepalives-out
interface ethernet 0
ip address 172.20.1.1 255.255.255.0
!
interface serial 0
x25 ltc 5
x25 pvc 1 interface serial 1 pvc 1
x25 pvc 2 xot 172.20.1.2 interface serial 0 pvc 1
!
interface serial 1
x25 ltc 5
x25 pvc 1 interface serial 0 pvc 1
x25 pvc 2 xot 172.20.1.2 interface serial 0 pvc 2
Configuration for Router Y
service tcp-keepalives-in
service tcp-keepalives-out
interface ethernet 0
ip address 172.20.1.2 255.255.255.0
!
interface serial 0
x25 ltc 5
x25 pvc 1 xot 172.20.1.1 interface serial 0 pvc 2
x25 pvc 2 xot 172.20.1.1 interface serial 1 pvc 2
X.25 Load Balancing Examples
For examples of X.25 load balancing, see the following sections:
•
•
X.25 Load Balancing Using VC-Count Distribution Method Example, page 86
X.25 Load Balancing with Multiple Hunt Groups Example, page 86
X.25 Load Balancing Using VC-Count Distribution Method Example
In the following example, the vc-count distribution method is used on two serial interfaces that have
different numbers of VCs. Assuming that no sessions are being terminated at this time, the first 450 calls
will be sent to Serial1, and subsequent calls will alternate between Serial0 and Serial1 until the interfaces
are full.
!
interface serial0
description 56k link supporting 50 virtual circuits
x25 htc 50
!
interface serial1
description T1 line supporting 500 virtual circuits
x25 htc 500
!
x25 hunt-group hg-vc vc-count
interface serial0
interface serial1
!
X.25 Load Balancing with Multiple Hunt Groups Example
The following example enables X.25 encapsulation on relevant serial interfaces and configures serial
interfaces 1 and 2 to participate in X.25 hunt group "HG1," and serial interfaces 0 and 3 to participate in X.
25 hunt group "HG2." Serial interfaces 1 and 2 and XOT IP addresses 172.17.125.54 and 172.17.125.34 are
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X.25 Switching Between PVCs and SVCs Example
X.25 Load Balancing with Multiple Hunt Groups Example
then associated with hunt group "HG1" (with rotary distribution assigned); and serial interfaces 0 and 3 are
associated with hunt group "HG2" (with vc-count distribution assigned). These hunt groups are then added
to the routing table, where X.25 route 1111 will use "HG1" and X.25 route 1112 will use "HG2".
x25 routing
interface serial 0
encapsulation x25
interface serial 1
encapsulation x25
interface serial 2
encapsulation x25
interface serial 3
encapsulation x25
!
x25 hunt-group HG1 rotary
interface serial 1
interface serial 2
xot 172.17.125.54
xot 172.17.125.34
exit
!
x25 hunt-group HG2 vc-count
interface serial0
interface serial3
exit
!
x25 route 1111 hunt-group HG1
x25 route 1112 hunt-group HG2
X.25 Switching Between PVCs and SVCs Example
The following example allows X.25 switching between a PVC on the first interface and an SVC on the
second interface. X.25 traffic arriving on PVC 20 on serial interface 0 will cause a call to be placed to
000000160100, if one does not already exist.
x25 routing
interface serial0
encapsulation x25
x25 address 000000180100
x25 ltc 128
x25 pvc 20 svc 000000160100 packetsize 128 128 windowsize 2 2
interface serial2
encapsulation x25 dce
x25 route ^000000160100$ interface Serial2
x25 route ^000000180100$ interface Serial0
The x25 route command adds the two X.121 addresses to the X.25 routing table. Data traffic received on
PVC 20 on serial interface 0 will cause a call to be placed with a Called (destination) Address of
000000160100; this call will be routed to serial interface 2. Alternatively, an X.25 call received with a
Called Address of 000000180100 and a Calling Address of 000000160100 will be associated with PVC 20
on serial interface 0. In either case, subsequent X.25 traffic on either the SVC or the PVC will be forwarded
to the other circuit. Because no idle timeout has been specified for the interface or for the circuit, the router
will not clear the call.
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Inserting and Removing X.121 Addresses As Calls Are Routed Example
X.25 Load Balancing with Multiple Hunt Groups Example
Inserting and Removing X.121 Addresses As Calls Are Routed Example
The following example shows insertions and removals in the X.121address as calls from the X.25 network
get routed to X.25 devices. The figure below shows the topology for this example.
Figure 13
Typical X.25 Network Configuration
Example Configuration
x25 route ^2(.*) input-interface serial1 substitute-dest \1 interface serial2
x25 route input-interface serial2 source .* substitute-source 2\0 interface serial0
For a call coming from interface serial 1 with a called address starting with 2, the 2 is stripped off the called
address and the call forwarded to serial interface 2.
For a call coming from interface serial 2 with any calling address, a 2 will be inserted to its calling address
and the call forwarded to serial interface 0.
Forwarding Calls Using the continue Keyword Example
This section provides two examples of the same configuration. Both examples show how to forward calls
among a number of local X.25 devices; however, the second example shows how the continue keyword
reduces the number of routing statements. (Keep in mind that the continue keyword is most useful when
you will be switching calls among four or more routes.)
The figure below illustrates the network topology for both examples.
Figure 14
X.25 Network with Multiple Interfaces
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Configuring X.25 and LAPB
X.25 Routing Statements Before continue Keyword
•
•
X.25 Routing Statements Before continue Keyword, page 89
Same X.25 Network Configuration with continue Keyword, page 89
X.25 Routing Statements Before continue Keyword
The following example shows how to forward calls among a number of local X.25 devices without using
the continue keyword:
x25 route
interface
x25 route
interface
x25 route
interface
x25 route
interface
!
x25 route
interface
x25 route
interface
x25 route
interface
x25 route
interface
!
x25 route
interface
x25 route
interface
x25 route
interface
x25 route
interface
!
x25 route
interface
x25 route
interface
x25 route
interface
x25 route
interface
!
x25 route
interface
x25 route
interface
x25 route
interface
x25 route
interface
^02 input-interface
serial 2
^03 input-interface
serial 3
^04 input-interface
serial 4
^05 input-interface
serial 5
serial 1 substitute-source 01\0 substitute-dest \1
^01 input-interface
serial 1
^03 input-interface
serial 3
^04 input-interface
serial 4
^05 input-interface
serial 5
serial 2 substitute-source 02\0 substitute-dest \1
^02 input-interface
serial 2
^01 input-interface
serial 1
^04 input-interface
serial 4
^05 input-interface
serial 5
serial 3 substitute-source 03\0 substitute-dest \1
^02 input-interface
serial 2
^03 input-interface
serial 3
^01 input-interface
serial 1
^05 input-interface
serial 5
serial 4 substitute-source 04\0 substitute-dest \1
^02 input-interface
serial 2
^03 input-interface
serial 3
^04 input-interface
serial 4
^01 input-interface
serial 1
serial 5 substitute-source 05\0 substitute-dest \1
serial 1 substitute-source 01\0 substitute-dest \1
serial 1 substitute-source 01\0 substitute-dest \1
serial 1 substitute-source 01\0 substitute-dest \1
serial 2 substitute-source 02\0 substitute-dest \1
serial 2 substitute-source 02\0 substitute-dest \1
serial 2 substitute-source 02\0 substitute-dest \1
serial 3 substitute-source 03\0 substitute-dest \1
serial 3 substitute-source 03\0 substitute-dest \1
serial 3 substitute-source 03\0 substitute-dest \1
serial 4 substitute-source 04\0 substitute-dest \1
serial 4 substitute-source 04\0 substitute-dest \1
serial 4 substitute-source 04\0 substitute-dest \1
serial 5 substitute-source 05\0 substitute-dest \1
serial 5 substitute-source 05\0 substitute-dest \1
serial 5 substitute-source 05\0 substitute-dest \1
Same X.25 Network Configuration with continue Keyword
The following example shows how to forward calls among a number of local X.25 devices using the
continue keyword:
x25
x25
x25
x25
x25
x25
x25
x25
route
route
route
route
route
route
route
route
input-interface serial 1 source .* substitute-source
input-interface serial 2 source .* substitute-source
input-interface serial 3 source .* substitute-source
input-interface serial 4 source .* substitute-source
input-interface serial 5 source .* substitute-source
^01(.*) substitute-dest \1 interface serial 1
^02(.*) substitute-dest \1 interface serial 2
^03(.*) substitute-dest \1 interface serial 3
01\0
02\0
03\0
04\0
05\0
continue
continue
continue
continue
continue
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DNS-Based X.25 Routing Example
Same X.25 Network Configuration with continue Keyword
x25 route ^04(.*) substitute-dest \1 interface serial 4
x25 route ^05(.*) substitute-dest \1 interface serial 5
DNS-Based X.25 Routing Example
The following example shows XOT switch configuration for XOT switching via the DNS:
Router(config)#
ip tcp synwait-time 5
Router(config)#
ip name-server 10.1.1.40
Router(config)#
x25 routing
Router(config)#
service pad to-xot
Router(config)#
service pad from-xot
Router(config)#
ip domain-name home.com
Router(config)#
ip domain-list home.com
Router(config)#
ip domain-lookup
Router(config)#
interface Ethernet1
Router(config-if)#
ip address 10.1.1.2 255.255.255.0
Router(config-if)#
exit
Router(config)#
interface Serial0
Router(config-if)#
encapsulation x25 dce
Router(config-if)#
exit
Router(config)#
x25 route 444 xot dns \0
Router(config)#
x25 route 555 xot dns \0
X.25overFrameRelayAnnexGExample
The following example configures X.25 profile "NetworkNodeA" (using the X.25 commands x25 htc, x25
idle, x25 accept-reverse and x25 modulo) on DLCI interfaces 20 and 30; and X.25 profile
"NetworkNodeB" (using the X.25 command x25 address) on DLCI interface 40; all on serial interface 1.
The example shows the final step of assigning your X.25 profile to the DLCI interface by using the framerelay interface-dlci command, and then assigning X.25 routes to DLCIs 20, 30, and 40 using the x25
route command.
The new x25 profile command mode (config-x25) can be seen in this example. This mode is used for
configuring the parameters of your X.25 profile. For a complete description of this command and mode,
refer to the x25 profile command section in the chapter "X.25 and LAPB Commands" in the Cisco IOS
Wide-Area Networking Command Reference.
This example assumes that you already have Frame Relay enabled on your router.
R
outer(config)#
x25 routing
Router(config)#
x25 profile NetworkNodeA dce
Router(config-x25)#
x25 htc 128
Router(config-x25)#
x25 idle 5
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CMNS Switching Example
Same X.25 Network Configuration with continue Keyword
Router(config-x25)#
x25 accept-reverse
Router(config-x25)#
x25 modulo 128
Router(config-x25)#
end
Router(config)#
x25 profile NetworkNodeB dce
Router(config-x25)#
x25 address 1111
Router(config-x25)#
end
Router(config)#
interface serial1
Router(config-if)#
encapsulation frame-relay
Router(config-if)#
frame-relay interface-dlci 20
Router(config-fr-dlci)#
x25-profile NetworkNodeA
Router(config-fr-dlci)#
end
Router(config)#
interface serial1
Router(config-if)#
frame-relay interface-dlci 30
Router(config-fr-dlci)#
x25-profile NetworkNodeA
Router(config-fr-dlci)#
end
Router(config)#
interface serial1
Router(config-if)#
frame-relay interface-dlci 40
Router(config-fr-dlci)#
x25-profile NetworkNodeB
Router(config-fr-dlci)#
end
Router(config)#
x25 route 2000 interface serial1 dlci 20
Router(config)#
x25 route 3000 interface serial1 dlci 30
Router(config)#
x25 route 4000 interface serial1 dlci 40
CMNS Switching Example
The following example illustrates enabling CMNS and configuring X.25 routes to the available CMNS host
and the PDN connectivity:
interface ethernet 0
cmns enable
!
interface serial 0
encapsulation x25
!
interface serial 1
encapsulation x25
!
x25 route dest-ext ^38.8261.1000.0150.1000.17 interface Ethernet0 mac 0000.0c00.ff89
! Above maps NSAP to MAC-address on Ethernet0
!
x25 route dest-ext ^38.8261.1000.0150.1000.18 substitute-dest 3110451 interface Serial0
! Above maps NSAP to X.121-address on Serial0 assuming the link is over a PDN
!
x25 route dest-ext ^38.8261.1000.0150.1000.20 interface Serial1
! Above specifies cmns support for Serial1
! assuming that the link is over a leased line
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CMNS Switching over a PDN Example
Same X.25 Network Configuration with continue Keyword
CMNS Switching over a PDN Example
The following example depicts switching CMNS over a packet-switched PDN. The figure below illustrates
the general network topology for a CMNS switching application where calls are being made between
resources on opposite sides of a remote link to Host A (on an Ethernet) and Host B (on a Token Ring), with
a PDN providing the connection.
Figure 15
Example Network Topology for Switching CMNS over a PDN
The following configuration listing allows resources on either side of the PDN to call host A or host B.
This configuration allows traffic intended for the remote NSAP address specified in the x25 route
commands (for the serial ports) to be switched through the serial interface for which CMNS is configured.
Configuration for Router C2
interface token 0
cmns enable
!
interface serial 0
encapsulation x25
x25 address 4085551234
!
x25 route dest-ext ^38.8261.17 interface Token0 mac 0800.4e02.1f9f
!
! The line above specifies that any traffic from any other interface
! intended for any NSAP address with NSAP prefix 38.8261.17 will be
! switched to MAC address 0800.4e02.1f9f through Token Ring 0
!
x25 route dest-ext ^38.8261.18 substitute-dest 2095551000 interface Serial0
!
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CMNS Switched over Leased Lines Example
Same X.25 Network Configuration with continue Keyword
!
!
!
!
The line above specifies that traffic from any other interface
on Cisco Router C2 that is intended for any NSAP address with
NSAP-prefix 38.8261.18 will be switched to
X.121 address 2095551000 through Serial 0
Configuration for Router C1
interface ethernet 0
cmns enable
!
interface serial 1
encapsulation x25
x25 address 2095551000
!
x25 route dest-ext ^38.8261.18 interface Ethernet0 mac 0800.4e02.2abc
!
! The line above specifies that any traffic from any other
! interface intended for any NSAP address with NSAP 38.8261.18
! will be switched to MAC address 0800.4e02.2abc through Ethernet 0
!
x25 route dest-ext ^38.8261.17 substitute-dest 4085551234 interface Serial1
!
! The line above specifies that traffic from any other interface
! on Cisco Router C1 that is intended for any NSAP address with
! NSAP-prefix 38.8261.17 will be switched to X.121 address
! 4085551234 through Serial 1
CMNS Switched over Leased Lines Example
The following example illustrates switching CMNS over a leased line. The figure below illustrates the
general network topology for a CMNS switching application where calls are being made by resources on
the opposite sides of a remote link to host C (on an Ethernet) and host B (on a Token Ring), with a
dedicated leased line providing the connection.
The following configuration listing allows resources on either side of the leased line to call host C or host
B. This configuration allows traffic intended for the remote NSAP address specified in the x25 route
commands (for the serial ports) to be switched through the serial interface for which CMNS is configured.
Figure 16
Example Network Topology for Switching CMNS over a Leased Line
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Configuring Local Acknowledgment Example
Same X.25 Network Configuration with continue Keyword
A key difference for this configuration compared with the previous example is that with no PDN, the
substitution of the destination X.121 address in the x25 route command is not necessary. The specification
of an X.25 address also is not needed, but it is included for symmetry with the previous example.
Configuration for Router C4
interface token 0
cmns enable
!
interface serial 0
encapsulation x25
x25 address 4085551234
!
x25 route dest-ext ^38.8261.17 interface Token0 mac 0800.4e02.1f9f
!
! The line above specifies that any traffic from any other interface
! intended for any NSAP address with NSAP prefix 38.8261.17 will be
! switched to MAC address 0800.4e02.1f9f through Token Ring 0
!
x25 route dest-ext ^38.8261.18 interface Serial0
!
! The line above specifies that traffic from any other interface
! on Cisco Router C2 that is intended for any NSAP address with
! NSAP-prefix 38.8261.18 will be switched to
! X.121 address 2095551000 through Serial 0
Configuration for Router C3
interface ethernet 0
cmns enable
!
interface serial 1
encapsulation x25
x25 address 2095551000
!
x25 route dest-ext ^38.8261.18 interface Ethernet0 mac 0800.4e02.2abc
!
! The line above specifies that any traffic from any other
! interface intended for any NSAP address with NSAP 38.8261.18
! will be switched to MAC address 0800.4e02.2abc through Ethernet 0
!
x25 route dest-ext ^38.8261.17 interface Serial1
!
! The line above specifies that traffic from any other interface
! on Cisco Router C1 that is intended for any NSAP address with
! NSAP-prefix 38.8261.17 will be switched to X.121 address
! 4085551234 through Serial 1
Configuring Local Acknowledgment Example
The following example shows X.25 local acknowledgment being configured on the router:
Router(config)# x25 routing acknowledge local
Setting Asymmetrical Window and Packet Sizes Flow Control Never
Example
The following example shows asymmetrical window and packet sizes being set on the router on serial
interfaces 0 and 1, with local acknowledgment enabled globally, and flow control disabled on both
interfaces to allow asymmetrical flow control to occur:
Router(config)#
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Configuring Flow Control Always Example
Same X.25 Network Configuration with continue Keyword
interface serial0
Router(config-if)#
x25 win 2
Router(config-if)#
x25 wout 3
Router(config-if)#
x25 ips 256
Router(config-if)#
x25 ops 512
Router(config-if)#
x25 ops 512
Router(config-if)#
exit
Router(config)#
interface serial1
Router(config-if)#
x25 win 4
Router(config-if)#
x25 wout 5
Router(config-if)#
x25 ips 128
Router(config-if)#
x25 ops 512
Router(config-if)#
exit
Router(config)#
x25 routing acknowledge local
Router(config)#
interface serial 0
Router(config-if)#
encapsulation x25 dte
Router(config-if)#
x25 subscribe flow-control never
Router(config-if)#
exit
Router(config)#
interface serial 1
Router(config-if)#
encapsulation x25 dte
Router(config-if)#
x25 subscribe flow-control never
Configuring Flow Control Always Example
The following example shows X.25 routing with local acknowledgment being enabled globally and flow
control negotiation being enabled on serial interface 1/4. Window size ranges are set at a permitted rate of 1
(minimum) and 7 (maximum) and target rate of 2 (minimum) and 4 (maximum).
Packet size ranges are set at a permitted rate of 64 (minimum) and 1024 (maximum), and target rate of 128
(minimum) and 1024 (maximum).
R
outer(config)#
x25 routing acknowledge local
Router(config)#
interface serial 1/4
Router(config-if)#
encapsulation x25 dte
Router(config-if)#
x25 subscribe flow-control always
Router(config-if)#
x25 subscribe windowsize permit 1 7 target 2 4
Router(config-if)#
x25 subscribe packetsize permit 64 1024 target 128 1024
You do not have to configure window and packet size ranges because their default settings are appropriate
for most configurations. The following example shows X.25 routing with local acknowledgment being
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X.25 CUGs Examples
X.25 CUG Service and Access with CUG Properties Example
enabled globally and flow control negotiation being enabled on serial interface 1/4 with default window
and packet size settings:
Router(config)#
interface serial 1/4
Router(config-if)#
encapsulation x25 dte
Router(config-if)#
x25 subscribe flow-control always
X.25 CUGs Examples
•
•
•
•
•
•
•
X.25 CUG Service and Access with CUG Properties Example, page 96
POP with No CUG Access Example, page 96
POP with Access Restricted to One CUG Example, page 97
POPwithMultipleCUGsandNoPublicAccessExample, page 97
POP with Multiple CUGs and Public Access Example, page 97
CUG Selection Facility Suppression for the Preferential CUG Example, page 98
CUG Selection Facility Suppression for All CUGs Example, page 98
X.25 CUG Service and Access with CUG Properties Example
In the following example, X.25 CUG service is being subscribed to on serial 0, which then permits the
subscription to local CUGs (5000, 100, 200, and 300). Subscription to local CUGs cannot be achieved
without subscription to X.25 CUG service (although this occurs automatically--with CUG service default
settings of no incoming and no outgoing access--the first time you subscribe to a specific CUG using the
x25 subscribe local-cug command).
Local CUG 5000 has been designated as the preferential CUG, which means that it will be used when a call
with no CUG membership selection is made. These local CUGs all belong to different network identifiers
(IDs) (local 5000 = network 55; local 100 = network 11; local 200 = network 22; local 300 = network 33),
but they could also subscribe to the same network ID if desired.
Router(config)#
interface serial0
Router(config-if)#
encapsulation x25 dce
Router(config-if)#
x25 subscribe cug-service incoming-access outgoing-access
Router(config-if)#
x25 subscribe local-cug 5000 network-cug 55 preferential
Router(config-if)#
x25 subscribe local-cug 100 network-cug 11
Router(config-if)#
x25 subscribe local-cug 200 network-cug 22
Router(config-if)#
x25 subscribe local-cug 300 network-cug 33
POP with No CUG Access Example
In the following example, serial interface 0 is being configured as a POP for a user that has no access to
any of the CUGs in the network, but full public access (incoming and outgoing access)--the least restrictive
setting:
Router(config)#
interface serial0
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Configuring X.25 and LAPB
POP with Access Restricted to One CUG Example
Router(config-if)#
encapsulation x25 dce
Router(config-if)#
x25 subscribe cug-service incoming-access outgoing-access
POP with Access Restricted to One CUG Example
In the following example, serial interface 0 is configured as a POP with access only to members of its own
CUG and no public access. The POP is being configured for CUG service security using the most
restrictive settings (the default) of the x25 subscribe cug-service command--no incoming and no outgoing
access permitted. Local CUG 5000, which is associated with network 55, is being subscribed to this POP.
An outgoing call from the DTE may select local CUG 5000 or not. Because there is only one CUG
subscribed to, its use is implicit. CUG 5000 will always select its related network CUG 55. An outgoing
call that specifies a different local CUG will be refused. An incoming call must specify network CUG 55;
otherwise the call will be refused.
Router(config)#
interface serial0
Router(config-if)#
encapsulation x25 dce
Router(config-if)#
x25 subscribe cug-service
Router(config-if)#
x25 subscribe local-cug 5000 network-cug 55
POPwithMultipleCUGsandNoPublicAccessExample
In the following example, serial interface 0 is being configured as a POP with access to members of several
CUGs, using the most restrictive settings (the default) of the x25 subscribe cug-service command--no
incoming and no outgoing access permitted. Local CUGs (5000, 100, 200, and 300) are then subscribed to
this POP. Local CUG 5000 has been designated as the preferential CUG, which means that it will be used
when a call with no CUG membership selection was made.
These local CUGs all belong to different networks (local 5000 = network 55; local 100 = network 11; local
200 = network 22; local 300 = network 33), but they could also subscribe to the same network if desired.
An outgoing call from the DTE may select any of the local CUGs (5000, 100, 200, and 300) or not.
Because there is a preferential CUG (5000), its use will be implicit when no CUG is specified. The related
network CUG (55) will be selected when switched to an intranetwork connection. A call specifying a
different local CUG will be refused. An incoming call must select one of the network CUGs (55, 11, 22, or
33); otherwise the call will be refused.
Router(config)#
interface serial0
Router(config-if)#
encapsulation x25 dce
Router(config-if)#
x25 subscribe cug-service
Router(config-if)#
x25 subscribe local-cug 5000 network-cug 55 preferential
Router(config-if)#
x25 subscribe local-cug 100 network-cug 11
Router(config-if)#
x25 subscribe local-cug 200 network-cug 22
Router(config-if)#
x25 subscribe local-cug 300 network-cug 33
POP with Multiple CUGs and Public Access Example
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DDN X.25 Configuration Example
CUG Selection Facility Suppression for the Preferential CUG Example
In the following example, serial interface 0 is being configured as a POP with public access to members of
several CUGs and the means to originate and receive calls from the open network (that is, to or from users
that do not subscribe to one of the CUGs to which this POP subscribes).
An outgoing call from the DTE may select any of the local CUGs (1, 2, 3, or 4) or not. When no CUG is
selected, it is assumed that the call is intended for the open network. When a CUG is selected, the related
network CUG will be selected when the call is switched to an intranetwork connection. The call will be
refused if it specifies a different local CUG from the one to which the POP is subscribed.
An incoming call to the DTE from an intra network connection may select related network CUGs (101,
202, 303, or 404) or no CUG. If no CUG is selected, the call is accepted as coming from the open network.
A call that requires access to a different CUG will be refused.
Router(config)#
interface serial0
Router(config-if)#
encapsulation x25 dce
Router(config-if)#
x25 subscribe cug-service incoming-access outgoing-access
Router(config-if)#
x25 subscribe local-cug 1 network-cug 101
Router(config-if)#
x25 subscribe local-cug 2 network-cug 202
Router(config-if)#
x25 subscribe local-cug 3 network-cug 303
Router(config-if)#
x25 subscribe local-cug 4 network-cug 404
CUG Selection Facility Suppression for the Preferential CUG Example
In the following example, CUG selection facility suppression is configured for the preferential CUG only
on serial interface 0:
interface serial0
encapsulation x25 dce
x25 subscribe cug-service suppress preferential
x25 subscribe local-cug 0 network-cug 10 preferential
x25 subscribe local-cug 50 network-cug 500
CUG Selection Facility Suppression for All CUGs Example
In the following example, CUG selection facility suppression and incoming access are configured for all
CUGs, including the preferential CUG on the X.25 profile:
x25 profile CUG-SUPRS-ALL dce
x25 subscribe cug-service incoming-access suppress all
x25 subscribe local-cug 0 network-cug 10 preferential
x25 subscribe local-cug 20 network-cug 202
x25 subscribe local-cug 40 network-cug 40
DDN X.25 Configuration Example
The following example illustrates how to configure a router interface to run DDN X.25:
interface serial 0
ip address 192.31.7.50 255.255.255.240
encapsulation x25 ddn
x25 win 6
x25 wout 6
x25 ips 1024
x25 ops 1024
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Blacker Front End Example
CUG Selection Facility Suppression for All CUGs Example
x25
x25
x25
x25
x25
x25
t20
t21
t22
t23
nvc
map
10
10
10
10
2
IP 192.31.7.49 000000010300 BROADCAST
Blacker Front End Example
In the following example, interface serial 0 is configured to attach to the DDN X.25 network via a Blacker
Front End.
interface serial 0
ip address 21.0.0.2 255.0.0.0
encapsulation x25 bfe
X.25 Ping Support over Multiple Lines Example
For ping commands to work in an X.25 environment (when load sharing is occurring over multiple serial
lines), you must include entries for all adjacent interface IP addresses in the x25 map command for each
serial interface. The following example illustrates this point.
Consider two routers, router A and router B, communicating with each other over two serial lines via an X.
25 PDN (see the figure below) or over leased lines. In either case, all serial lines must be configured for the
same IP subnet address space. The configuration that follows allows for successful ping commands. A
similar configuration is required for the same subnet IP addresses to work across X.25.
Figure 17
Note
Parallel Serial Lines to an X.25 Network
All four serial ports configured for the two routers in the following configuration example must be assigned
to the same IP subnet address space. In this case, the subnet is 172.20.170.0.
Configuration for Router A
interface serial 1
ip 172.20.170.1 255.255.255.0
x25 address 31370054068
x25 alias ^31370054069$
x25 map ip 172.20.170.3 31370054065
x25 map ip 172.20.170.4 31370054065
!
interface serial 2
ip 172.20.170.2 255.255.255.0
x25 address 31370054069
x25 alias ^31370054068$
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Booting from a Network Server over X.25 Example
X.25 Remote Failure Detection with IP Static Routes Example
x25 map ip 172.20.170.4 31370054067
x25 map ip 171.20.170.3 31370054067
! allow either destination address
Configuration for Router B
interface serial 0
ip 172.20.170.3 255.255.255.0
x25 address 31370054065
x25 alias ^31370054067$
x25 map ip 172.20.170.1 31370054068
x25 map ip 172.20.170.2 31370054068
!
interface serial 3
ip 172.20.170.4 255.255.255.0
x25 address 31370054067
x25 alias ^31370054065$
x25 map ip 172.20.170.2 31370054069
x25 map ip 172.20.170.1 31370054069
! allow either destination address
Booting from a Network Server over X.25 Example
You cannot boot a router over an X.25 network using broadcasts. Instead, you must boot from a specific
host. Also, an x25 map command must exist for the host that you boot from. The x25 map command maps
an IP address to an X.121 address. The x25 map command must match the IP address given on the boot
system command line. The following is an example of such a configuration:
boot system gs3-k.100 172.18.126.111
interface Serial 1
ip address 172.18.126.200 255.255.255.0
encapsulation X25
x25 address 10004
x25 map IP 172.18.126.111 10002 broadcast
lapb n1 12040
clockrate 56000
In this case, 10002 is the X.121 address of the remote router that can get to host 172.18.126.111. The
remote router must have the following x25 map entry for the remote router to return a boot image from the
host to the router booting over X.25.
x25 map IP 172.18.126.200 10004 broadcast
X.25 Remote Failure Detection Examples
You must have X.25 encapsulation activated for X.25 remote failure detection to function. See the section
Configuring X.25 Encapsulation, page 46 for further details. You must also have IP static routes or a
backup link configured for X.25 encapsulation.
These examples show the x25 retry command being used only with a secondary route. However, the x25
retry command can be configured for as many subinterfaces that require an alternative route. Use either
one of the following examples to configure X.25 remote failure detection:
•
•
X.25 Remote Failure Detection with IP Static Routes Example, page 100
X.25 Remote Failure Detection and the Backup Interface Example, page 101
X.25 Remote Failure Detection with IP Static Routes Example
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X.29 Access List Example
X.25 Remote Failure Detection and the Backup Interface Example
The following is an example of X.25 remote failure detection being configured on subinterfaces 1.1 and 1.2
using the x25 retry command. Subinterface 1.1 has been set at a retry every 60 seconds up to a maximum
of 10 attempts.
Observe the weighting of 100 on subinterface 1.1 over 200 on subinterface 1.2 in the ip route command,
because subinterface 1.1 is the primary route and 1.2 is the secondary route. The latter becomes activated
only when subinterface 1.1 is unable to function. Weights make for predictable routing events and therefore
promote the concept of primary and secondary routes.
Router(config)# interface serial1
Router(config-if)# encapsulation x25
Router(config-if)# x25 address 11111
Router(config-if)# exit
Router(config)# interface serial1.1 point-to-point
Router(config-subif)# ip address 172.30.22.1 255.255.255.0
Router(config-subif)# x25 map ip 172.30.22.2 22222
Router(config-subif)# x25 retry interval 60 attempts 10
Router(config-subif)# exit
Router(config)# interface serial1.2 point-to-point
Router(config-subif)# ip address 172.30.22.1 255.255.255.0
Router(config-subif)# x25 map ip 172.30.22.4 44444
Router(config-subif)# exit
Router(config)# ip route 172.30.11.1 255.255.255.0 serial1.1 100
Router(config)# ip route 172.30.11.1 255.255.255.0 serial1.2 200
X.25 Remote Failure Detection and the Backup Interface Example
The following configuration example is an alternative to the method previously described. X.25 remote
failure detection is configured on subinterface 1.1, and interface 2 is made the backup interface. The x25
retry command has been set with an interval of 50 seconds up to a maximum of 20 attempts. In this
example, there is no need to configure any IP static routes (as is done with the above configuration)
because the backup interface is functioning as the secondary route. In other situations, there may be a need
for static IP routes, depending on how the backup interface is configured.
For more details about backup, see the backup interfacecommand in the chapter in the Cisco IOS Dial
Technologies Command Reference.
Router(config)# interface serial1
Router(config-if)# encapsulation x25
Router(config-if)# x25 address 11111
Router(config-if)# exit
Router(config)# interface serial1.1 point-to-point
Router(config-subif)# ip address 172.30.22.1 255.255.255.0
Router(config-subif)# x25 map ip 172.30.22.2 22222
Router(config-subif)# x25 retry interval 50 attempts 20
Router(config-subif)# backup interface serial2
Router(config-subif)# exit
Router(config)# interface serial2
Router(config-if)# encapsulation x25
Router(config-if)# x25 address 11111
Router(config-if)# ip address 172.30.22.1 255.255.255.0
Router(config-if)# x25 map ip 172.30.22.3 33333
Router(config-if)# exit
X.29 Access List Example
The following example illustrates an X.29 access list. Incoming permit conditions are set for all IP hosts
and LAT nodes that have specific characters in their names. All X.25 connections to a printer are denied.
Outgoing connections are list restricted.
!Permit all IP hosts and LAT nodes beginning with "VMS".
!Deny X.25 connections to the printer on line 5.
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X.29 Profile Script Example
!
access-list 1 permit 0.0.0.0 255.255.255.255
lat access-list 1 permit ^VMS.*
x29 access-list 1 deny .*
!
line vty 5
access-class 1 in
!
!Permit outgoing connections for other lines.
!
!Permit IP access with the network 172.30
access-list 2 permit 172.30.0.0 0.0.255.255
!
!Permit LAT access to the boojum/snark complexes.
lat access-list 2 permit ^boojum$
lat access-list 2 permit ^snark$
!
!Permit X.25 connections to Infonet hosts only.
x29 access-list 2 permit ^31370
!
line vty 0 16
access-class 2 out
X.29 Profile Script Example
The following profile script turns local edit mode on when the connection is made and establishes local
echo and line termination upon receipt of a Return. The name linemode is used with the translate
command to effect use of this script.
x29 profile linemode 2:1 3:2 15:1
translate tcp 172.30.1.26 x25 55551234 profile linemode
The X.3 PAD parameters set in the profile file and the translate command are described in the chapter
"Configuring Protocol Translation and Virtual Asynchronous Devices" in the Cisco IOS Terminal Services
Configuration Guide .
Cisco and the Cisco Logo are trademarks of Cisco Systems, Inc. and/or its affiliates in the U.S. and other
countries. A listing of Cisco's trademarks can be found at www.cisco.com/go/trademarks. Third party
trademarks mentioned are the property of their respective owners. The use of the word partner does not
imply a partnership relationship between Cisco and any other company. (1005R)
Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be
actual addresses and phone numbers. Any examples, command display output, network topology diagrams,
and other figures included in the document are shown for illustrative purposes only. Any use of actual IP
addresses or phone numbers in illustrative content is unintentional and coincidental.
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Terminal Line Security for PAD Connections
This document describes the Terminal Line Security for PAD Connections feature. The Terminal Line
Security for PAD Connections feature allows a CUG service to be configured on terminal lines, enabling
terminal lines to participate in X.25 CUG security for packet assembler/disassembler (PAD) connections.
•
•
•
•
•
•
•
•
•
Finding Feature Information, page 103
Prerequisites for Terminal Line Security for PAD Connections, page 103
Restrictions for Terminal Line Security for PAD Connections, page 103
Information About Terminal Line Security for PAD Connections, page 104
How to Configure Terminal Line Security for PAD Connections, page 107
Configuration Examples for Terminal Line Security for PAD Connections, page 110
Additional References, page 110
Feature Information for Terminal Line Security for PAD Connections, page 111
Glossary, page 112
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest feature
information and caveats, see the release notes for your platform and software release. To find information
about the features documented in this module, and to see a list of the releases in which each feature is
supported, see the Feature Information Table at the end of this document.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support.
To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Prerequisites for Terminal Line Security for PAD Connections
The tasks in this document assume a basic understanding of the X.25 CUG service and how it works.
Restrictions for Terminal Line Security for PAD Connections
The CUG selection facility suppression options are not available for terminal lines because incoming PAD
calls are terminated by the terminal line.
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Security Considerations
Information About Terminal Line Security for PAD Connections
Information About Terminal Line Security for PAD
Connections
X.25 closed user group (CUG) service is a network service that allows subscribers to be segregated into
private subnetworks with limited outgoing and incoming access. A data terminal equipment (DTE) device
becomes a member of a CUG by subscription; the DTE must obtain membership from its network service
for the set of CUGs to which it needs access.
The Terminal Line Security for PAD Connections feature allows a CUG service to be configured on
terminal lines, enabling terminal lines to participate in X.25 CUG security for packet assembler/
disassembler (PAD) connections. A CUG service can be applied to console lines, auxiliary lines, and tty
and vty devices. Configuring a CUG service on terminal lines allows you to specify CUG protection for
lines that are part of the point of presence (POP). Before the introduction of this feature, a CUG service
could be configured only on X.25 synchronous data communications equipment (DCE) interfaces.
A line configured for CUG service will apply CUG security to PAD, X.28 mode, and protocol translation
sessions. The Terminal Line Security for PAD Connections feature ensures that CUG protection is applied
to incoming calls destined for the terminal line and call requests specified from the line. This feature also
supports the signaling of the CUG selection facility in call requests that originated on the line and incoming
calls received on an X.25 service that are terminated by the line.
Figure 1 shows a typical topology in which CUG service would be configured on asynchronous terminal
lines.
Figure 18
•
•
•
Network Topology with Asynchronous Lines Configured for CUG Service
Security Considerations, page 104
PAD Call Behavior When a Line Is Configured for CUG Subscription, page 104
Benefits, page 107
Security Considerations
Caution
X.25 CUG security relies on the correct, complementary configuration of CUG sets at all the boundaries
between customer premises equipment (CPE) and POPs. Any POP that is connected to a CPE device that is
not configured for CUG security has compromised the X.25 network security because that CPE device will
be a considered a trusted host, even though it is not secure.
PAD Call Behavior When a Line Is Configured for CUG Subscription
This section describes the overall behavior of PAD-initiated calls when a terminal line or an X.25 interface
is configured for CUG subscription.
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Terminal Line Security for PAD Connections
PAD Call Behavior When Only the Line is Configured for CUG Service
The x25 map pad and x25 facility cug commands can be used to cause a CUG selection facility to be
encoded in calls placed within the networks. The following rules describe which CUG selection facility is
encoded in the call:
•
•
A call initiated using the pad command or in X.28 mode without a CUG subscription set encodes the
interface CUG selection facility, if one was specified.
A call initiated using the pad command with the /use-map option encodes the CUG selection facility
for the matching map entry, if one was specified.
A call initiated in X.28 mode with a specified CUG encodes the specified X.28 CUG.
•
•
PAD Call Behavior When Only the Line is Configured for CUG Service, page 105
PAD Call Behavior When Both a Line and an Interface Are Configured for CUG Service, page 106
•
PAD Call Behavior When Only the Line is Configured for CUG Service
This section describes PAD call behavior when only the line is configured for CUG service.
Configuration A
In the following example, a line is configured for CUG subscription, and the interface on which the
resulting call is to be placed is configured with the x25 facility cug and x25 map pad commands. CUG
subscription is not configured on the interface.
interface Serial1
encapsulation x25 dce
x25 facility cug 99
x25 map pad 1221 cug 10 no-outgoing
x25 map pad 1222 cug 99
x25 map pad 1234 cug 10
!
line tty 1
x25 subscribe cug-service
x25 subscribe local-cug 99 network-cug 9999 preferential
x25 subscribe local-cug 10 network-cug 100
x25 subscribe local-cug 20 network-cug 200
!
[...]
!
x25 route ^12..$ interface Serial1
[...]
When the line initiates an X.28 mode or PAD call without a CUG subscription set, the line will decode the
interface’s CUG selection facility, and the network will encode the line’s signaled CUG selection facility.
The x25 facility cug command implicitly identifies the local CUG to use for PAD-originated calls.
The table below shows the CUG value sent when a line initiates a PAD or an X.28 mode call without a
CUG subscription set.
Table 3
CUG Value Sent for Line-Initiated Calls Without a CUG Subscription
User Command
Result
pad 1234
Call 1234, CUG 9999 sent on Serial 1.
*1234
Call 1234, CUG 9999 sent on Serial 1.
Using configuration A, if a call is initiated on a line using the pad command with the /use-map option, the
line will decode the matching map entry’s CUG, and the network will encode the line’s signaled CUG
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Terminal Line Security for PAD Connections
PAD Call Behavior When Both a Line and an Interface Are Configured for CUG Service
selection facility. The map’s CUG identifies the local CUG to use for PAD-originated calls and overrides
the interface's CUG selection facility on a per-call basis.
If the pad command is used with the /use-map option, the interface on which the resulting call is to be
placed must have a matching X.25 map statement for the PAD call and must permit outgoing calls. Any
CUG specified in the map statement must identify the local CUG ID to be used for generating the call.
The table below shows the values sent when a line initiates a PAD call with the /use-map option.
Table 4
CUG Value Sent for Line-Initiated PAD Calls Initiated with the /use-mapOption
User Command
Result
pad 1234 /use-map
Call 1234, CUG 100 sent on Serial 1.
pad 1221 /use-map
Call is cleared, outgoing calls are barred.
pad 1255 /use-map
Call is cleared (no matching map found on Serial
1).
Using configuration A, if an X.28 mode call specifies a CUG, the line will decode the specified CUG, and
the network will encode the line's signaled CUG selection facility. The X.28 mode commands do not use X.
25 map statements when originating calls.
The table below shows the CUG value sent when a line initiates a call using an X.28 interface with CUG
specified.
Table 5
CUG Value Sent for Line-Initiated Calls Using an X.28 Mode with CUG Specified
User Command
Result
*g10-1234
Call 1234, CUG 100 sent on Serial 1.
PAD Call Behavior When Both a Line and an Interface Are Configured for CUG Service
This section describes PAD call behavior when a line and an interface are both configured for CUG
service.
Configuration B
In the following example a line and an interface are configured for CUG subscription:
interface Serial1
encapsulation x25 dce
x25 subscribe cug-service
x25 subscribe local-cug 5599 network-cug 9999 preferential
x25 subscribe local-cug 5510 network-cug 100
x25 subscribe local-cug 5520 network-cug 200
x25 facility cug 99
x25 map pad 1234 cug 10
x25 map pad 1221 cug 10 no-outgoing
x25 map pad 1222 cug 99
!
line tty 1
x25 subscribe cug-service
x25 subscribe local-cug 10 network-cug 100
x25 subscribe local-cug 20 network-cug 200
x25 subscribe local-cug 99 network-cug 9999 preferential
!
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Benefits
How to Configure Terminal Line Security for PAD Connections
[...]
!
x25 route ^12..$ interface Serial1
[...]
The table below shows examples of line-initiated PAD commands and the CUG values sent when the
terminal line and the X.25 interface are both configured for CUG subscription.
Table 6
CUG Values Sent for Line-Initiated Calls When the Line and Interface Are Configured for CUG
Subscription
User Command
Result
pad 1234
Call 1234, CUG 5599 sent on Serial 1.
pad 1221
Call 1221, CUG 5599 sent on Serial 1.
pad 1222
Call 1222, CUG 5599 sent on Serial 1.
pad 1234 /use-map
Call 1234, CUG 5510 send on Serial 1.
pad 1221 /use-map
Call is cleared, outgoing calls are barred
pad 1222 /use-map
Call 1222, CUG 5599 sent on Serial 1
Benefits
Before the introduction of this feature, CUG functionality required all CPE devices to be attached to the
router at an X.25 synchronous DCE interface. The Terminal Line Security for PAD Connections feature
extends the existing X.25 CUG functionality to terminal lines, allowing PAD access devices (console lines,
auxiliary lines, and tty and vty devices) to be configured for CUG security enforcement.
How to Configure Terminal Line Security for PAD
Connections
•
•
•
Configuring X.25 CUG Support on Terminal Lines, page 107
Verifying X.25 CUG Support on Terminal Lines, page 108
Monitoring and Maintaining X.25 CUG Support on Terminal Lines, page 109
Configuring X.25 CUG Support on Terminal Lines
To configure X.25 CUG support on terminal lines, use the following commands beginning in global
configuration mode:
SUMMARY STEPS
1. Router(config)# line [aux | console | tty | vty] line-number [ending-line-number]
2. Router(config-line)# x25 subscribe cug-service [incoming-access | outgoing-access]
3. Router(config-line)# x25 subscribe local-cug number network-cug number [no-incoming | nooutgoing | preferential
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Verifying X.25 CUG Support on Terminal Lines
How to Configure Terminal Line Security for PAD Connections
DETAILED STEPS
Command or Action
Step 1 Router(config)# line [aux | console | tty |
vty] line-number [ending-line-number]
Purpose
Identifies a specific line or range of lines for configuration and enters line
configuration mode.
Step 2 Router(config-line)# x25 subscribe cugEnables and controls standard CUG behavior. CUG protection will be
service [incoming-access | outgoing-access] applied to PAD calls destined for and originated on the line.
Note The CUG selection facility suppression option is not available for
terminal lines because incoming PAD calls are terminated by the
line.
Step 3 Router(config-line)# x25 subscribe localcug number network-cug number [noincoming | no-outgoing | preferential
Configures subscription to a specific CUG and maps the desired local CUG
number to its corresponding network CUG.
This command can be entered as many times as needed to configure the
access needs of a line.
Verifying X.25 CUG Support on Terminal Lines
To verify support for X.25 CUG service on terminal lines, perform the following steps:
SUMMARY STEPS
1. Enter the show running-config command to verify that the configuration is correct.
2. Enter the show line command to display the configured CUG capability in the Capabilities field:
3. Enter the show x25 cug command with the local-cug keyword to display information about all local
CUGs configured on the router:
4. Enter the show x25 cug command with the network-cug keyword to display information about all
network CUGs configured on the router. The following sample output displays the local CUGs
associated with network CUG 10:
DETAILED STEPS
Step 1
Step 2
Enter the show running-config command to verify that the configuration is correct.
Enter the show line command to display the configured CUG capability in the Capabilities field:
Example:
Router# show line vty 2
Tty Typ
Tx/Rx
A Modem Roty AccO AccI
Uses
Noise Overruns
132 VTY
0
0
0/0
Line 132, Location: "", Type: ""
Length: 24 lines, Width: 80 columns
Baud rate (TX/RX) is 9600/9600
Status: No Exit Banner
Capabilities: CUG Security Enabled
Modem state: Idle
Group codes:
0
Special Chars: Escape Hold Stop Start Disconnect Activation
^^x
none
none
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Int
-
Monitoring and Maintaining X.25 CUG Support on Terminal Lines
How to Configure Terminal Line Security for PAD Connections
Timeouts:
Idle EXEC
00:10:00
Idle Session
Modem Answer Session
never
none
Idle Session Disconnect Warning
never
Login-sequence User Response
00:00:30
Autoselect Initial Wait
not set
Dispatch
not set
Modem type is unknown.
Session limit is not set.
.
.
.
Step 3
Enter the show x25 cug command with the local-cug keyword to display information about all local CUGs configured
on the router:
Example:
Router# show x25 cug local-cug
X.25 Serial1/1, 3 CUGs subscribed with no public access
local-cug 99 <-> network-cug 9999, no-incoming, preferential
local-cug 100 <-> network-cug 1000
local-cug 101 <-> network-cug 1001
PROFILE cugs, 2 CUGs subscribed with with incoming public access
local-cug 1 <-> network-cug 10, no-outgoing
local-cug 2 <-> network-cug 20, no-incoming, preferential
Line: 129 aux 0 , 1 CUGs subscribed with outgoing public access
local-cug 1 <-> network-cug 10
Line: 130 vty 0 , 4 CUGs subscribed with incoming and outgoing public access
local-cug 1 <-> network-cug 10
local-cug 50 <-> network-cug 5, preferential
local-cug 60 <-> network-cug 6, no-incoming
local-cug 70 <-> network-cug 7, no-outgoing
Line: 131 vty 1
, 1 CUGs subscribed with no public access
local-cug 1 <-> network-cug 10
Step 4
Enter the show x25 cug command with the network-cug keyword to display information about all network CUGs
configured on the router. The following sample output displays the local CUGs associated with network CUG 10:
Example:
Router# show x25 cug network-cug 10
PROFILE cugs, 2 CUGs subscribed with no public access
network-cug 10 <-> local-cug 1 , no-outgoing
Line: 129 aux 0
, 1 CUGs subscribed with no public access
network-cug 10 <-> local-cug 1
Line: 130 vty 0
, 4 CUGs subscribed with incoming and outgoing public access
network-cug 10 <-> local-cug 1
Line: 131 vty 1
, 1 CUGs subscribed with no public access
network-cug 10 <-> local-cug 1
Monitoring and Maintaining X.25 CUG Support on Terminal Lines
To monitor and maintain X.25 CUG support on terminal lines, use the following command in privileged
EXEC mode:
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Configuring X.25 CUG Support on Terminal Lines Example
Configuration Examples for Terminal Line Security for PAD Connections
Command
Router#
debug pad
Purpose
Displays debug messages for all PAD connections.
Configuration Examples for Terminal Line Security for PAD
Connections
•
Configuring X.25 CUG Support on Terminal Lines Example, page 110
Configuring X.25 CUG Support on Terminal Lines Example
The following example shows the configuration of CUG behavior on asynchronous line 1 and virtual
terminal lines 0 to 9. The user of async line 1 has only outgoing access to CPE that is subscribed to the
corporate CUG designated for finance (CUG 1101) but can receive calls from those same CUG members or
from the open network (that is, calls from a network X.25-class service that are destined for the line and
have no CUG restriction).
The users of virtual terminal lines 0 to 9 have access only within the corporate CUGs designated for
engineering (CUGs 1102 or 1103). Any call from a network X.25-class service destined for the line will be
refused unless the inbound POP validates it as a member of one of those two CUGs.
Line 1
Location Company A. Finance Connection
x25 subscribe cug-service incoming-access
x25 subscribe local-cug 1 network-cug 1101 preferential
!
line vty 0 9
Location Company A. Engineering Access
x25 subscribe cug-service
x25 subscribe local-cug 2 network-cug 1102 preferential
x25 subscribe local-cug 3 network-cug 1103
!
Additional References
Related Documents
Related Topic
Document Title
Cisco IOS commands
Cisco IOS Master Commands List, All Releases
Wide-Area Networking commands
Cisco IOS Wide-Area Networking Command
Reference
X.25 and LAPB configuration
Configuring X.25 and LAPB
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
110
Terminal Line Security for PAD Connections
Feature Information for Terminal Line Security for PAD Connections
Related Topic
Document Title
PAD Connections
•
•
Configuring the Cisco PAD Facility for X.25
Connections
Cisco IOS Terminal Services Command
Reference
Standards
Standard
Title
None
--
MIBs
MIB
MIBs Link
None
To locate and download MIBs for selected
platforms, Cisco software releases, and feature sets,
use Cisco MIB Locator found at the following
URL:
http://www.cisco.com/go/mibs
RFCs
RFC
Title
None
--
Technical Assistance
Description
Link
The Cisco Support and Documentation website
provides online resources to download
documentation, software, and tools. Use these
resources to install and configure the software and
to troubleshoot and resolve technical issues with
Cisco products and technologies. Access to most
tools on the Cisco Support and Documentation
website requires a Cisco.com user ID and
password.
http://www.cisco.com/cisco/web/support/
index.html
Feature Information for Terminal Line Security for PAD
Connections
The following table provides release information about the feature or features described in this module.
This table lists only the software release that introduced support for a given feature in a given software
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
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Terminal Line Security for PAD Connections
Glossary
release train. Unless noted otherwise, subsequent releases of that software release train also support that
feature.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support.
To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Table 7
Feature Information for Terminal Line Security for PAD Connections
Feature Name
Releases
Feature Information
Terminal Line Security for PAD
Connections
12.2(13)T
The Terminal Line Security for
PAD Connections feature allows
a CUG service to be configured
on terminal lines, enabling
terminal lines to participate in X.
25 CUG security for packet
assembler/disassembler (PAD)
connections.
The following commands were
introduced or modified: debug
pad, show line, show x25 cug,
x25 subscribe cug-service, x25
subscribe local-cug.
Glossary
call request --An X.25 call packet sent from a DTE to a DCE that initiates a connection to a destination
DTE.
closed user group selection facility --A specific encoding element that can be presented in a call request
or incoming call. A CUG selection facility in a call request allows the source DTE to identify the CUG
within which it is placing the call. A CUG selection facility in an incoming call allows the destination DTE
to identify the CUG to which both DTEs belong.
CPE --customer premises equipment. Terminating equipment, such as terminals, telephones, and modems,
supplied by the telephone company, installed at customer sites, and connected to the telephone company
network. This equipment is available for customer modification and is considered insecure by the network.
CUG --closed user group. A collection of DTE devices for which the network controls access among
members and between members and nonmembers. A DTE may subscribe to zero, one, or more CUGs. A
DTE that does not subscribe to a CUG is referred to as being in the open part of the network.
DCE --data communications equipment. A network connection where a subscriber can be attached. A DCE
is configured with the operational details for which a given subscriber (DTE) has contracted.
DTE --data terminal equipment. A network subscriber that can be reached at a specific network attachment
point. A network identifies each DTE device by assigning an X.121 address.
incoming call --An X.25 call packet sent from a DCE to a DTE that presents a connection requested by the
source DTE.
PAD --packet assembler/disassembler. Device used to connect simple devices (like character-mode
terminals) that do not support the full functionality of a particular protocol to a network. PADs buffer data
and assemble and disassemble packets sent to such end devices.
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Terminal Line Security for PAD Connections
POP --point of presence. In the context of a public data network, a POP is the part of the network to which
CPE is attached. A POP is configured and controlled by the public network and serves as the boundary
equipment between the trusted network and insecure client attachments.
preferential closed user group --The CUG that is assumed when a CUG is not specified in call setup. A
DTE that subscribes to more than one CUG and does not have incoming or outgoing access must designate
a preferred CUG.
Cisco and the Cisco Logo are trademarks of Cisco Systems, Inc. and/or its affiliates in the U.S. and other
countries. A listing of Cisco's trademarks can be found at www.cisco.com/go/trademarks. Third party
trademarks mentioned are the property of their respective owners. The use of the word partner does not
imply a partnership relationship between Cisco and any other company. (1005R)
Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be
actual addresses and phone numbers. Any examples, command display output, network topology diagrams,
and other figures included in the document are shown for illustrative purposes only. Any use of actual IP
addresses or phone numbers in illustrative content is unintentional and coincidental.
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
113
Configuring X.25 CUG Support on Terminal Lines Example
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
114
X.25 Annex G Session Status Change Reporting
This feature module describes the X.25 Annex G Session Status Change Reporting feature and includes
the following sections:
•
•
•
•
•
•
•
Finding Feature Information, page 115
Feature Overview, page 115
Supported Platforms, page 116
Supported Standards and MIBs and RFCs, page 116
Prerequisites, page 117
Configuration Tasks, page 117
Configuration Examples, page 117
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest feature
information and caveats, see the release notes for your platform and software release. To find information
about the features documented in this module, and to see a list of the releases in which each feature is
supported, see the Feature Information Table at the end of this document.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support.
To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Feature Overview
The X.25 Annex G Session Status Change Reporting feature introduces the logging event frame-relay x25
interface configuration command, which provides console or system log notification of X.25 Annex G
session status changes when an X.25 Annex G session changes state. Before this feature was introduced,
there was no notification.
This feature detects changes in X.25 Annex G session status using an X.25 Link Access Procedure,
Balanced (LAPB) N2 counter. The LAPB N2 counter records the number of unsuccessful transmit attempts
that are made before the link is declared down. If the N2 consecutive polled commands have not been
answered, a notification is generated, indicating that the X.25 profile or context associated with the datalink connection identifier (DLCI) that is running across the failed link has gone down. A message is
generated to the console or system log when the link goes down. A message is also generated to the console
or system log when the link comes back up. The notification response time is contingent on the values
assigned to the LAPB N2 counter and the LAPB the retransmission timer in milliseconds (T1) timer.
•
•
Benefits, page 116
Restrictions, page 116
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115
Benefits
Supported Platforms
•
Related Documents, page 116
Benefits
For X.25 Annex G sessions, if Local Management Interface (LMI) keepalives are disabled, Frame Relay
(FR) DLCI status changes can be detected using the logging event frame-relay x25 interface configuration
command
Restrictions
The following restrictions apply to the X.25 Annex G Session Status Change Reporting feature:
•
•
•
Notification is displayed for the UP or DOWN event only if traffic is initiated when an X.25 Annex G
session is active.
The notification response time is contingent on the values assigned to the LAPB N2 counter and the
LAPB T1 timer.
The PVCs continue to be reported as UP unless the serial link directly connected to the router goes
down.
Related Documents
•
•
Cisco IOS Wide-Area Networking Configuration Guide, Release 12.2
Cisco IOS Wide-Area Networking Command Reference, Release 12.2
Supported Platforms
•
•
•
•
•
•
•
•
•
•
Cisco 1600 series
Cisco 2500
Cisco 2600
Cisco 3640
Cisco 3660
Cisco 4000
Cisco 4500
Cisco 7000 series
Cisco 7200 series
Cisco 7500 series
Supported Standards and MIBs and RFCs
Standards
No new or modified standards are supported by this feature.
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
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Enabling X.25 Annex G Session Status Change Reporting
Prerequisites
MIBs
No new or modified MIBs are supported by this feature.
To obtain lists of supported MIBs by platform and Cisco IOS release, and to download MIB modules, go to
the Cisco MIB website on Cisco.com at http://www.cisco.com/public/sw-center/netmgmt/cmtk/
mibs.shtml .
RFCs
No new or modified RFCs are supported by this feature.
Prerequisites
The logging event frame-relay x25 interface configuration command is available for all interfaces that
have Frame Relay ecapsulation.
Configuration Tasks
•
•
Enabling X.25 Annex G Session Status Change Reporting, page 117
Verifying X.25 Annex G Session Status Change Reporting, page 117
Enabling X.25 Annex G Session Status Change Reporting
Purpose
Command
Router(config-if)#
logging event frame-
relay x25
Enables notification of X.25 Annex G session status
changes to be displayed on a console or system log.
Verifying X.25 Annex G Session Status Change Reporting
Command
Purpose
Router(config-if)#
show run logging event
Shows whether the command is enabled.
frame-relay x25
Configuration Examples
•
X.25 Annex G Session Status Change Reporting Configuration Example, page 118
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
117
X.25 Annex G Session Status Change Reporting Configuration Example
X.25 Annex G Session Status Change Reporting Configuration Example
The following configuration example shows how to enable notification of X.25 Annex G session status
changes to be displayed on a console or system log using the logging event frame-relay x25 interface
configuration command:
router(config-if)# logging event frame-relay x25
The following is an example of the Annex G session status change notifications:
%X25-5-UPDOWN: Interface <interface> - DLCI <dlci number> X.25 packet layer changed state
to DOWN
%X25-5-UPDOWN: Interface <interface> - DLCI <dlci number> X25 packet layer changed state
to UP
Cisco and the Cisco Logo are trademarks of Cisco Systems, Inc. and/or its affiliates in the U.S. and other
countries. A listing of Cisco's trademarks can be found at www.cisco.com/go/trademarks. Third party
trademarks mentioned are the property of their respective owners. The use of the word partner does not
imply a partnership relationship between Cisco and any other company. (1005R)
Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be
actual addresses and phone numbers. Any examples, command display output, network topology diagrams,
and other figures included in the document are shown for illustrative purposes only. Any use of actual IP
addresses or phone numbers in illustrative content is unintentional and coincidental.
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
118
X.25 Dual Serial Line Management
Feature History
Release
Modification
12.2(13)T
This feature was introduced.
This document describes the X.25 Dual Serial Line Management feature in Cisco IOS Release 12.2(13)T.
It includes the following sections:
•
•
•
•
•
•
Finding Feature Information, page 119
Feature Overview, page 119
Supported Standards and MIBs and RFCs, page 121
Configuration Tasks, page 122
X.25 Dual Serial Line Management Configuration Example, page 124
Glossary, page 125
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest feature
information and caveats, see the release notes for your platform and software release. To find information
about the features documented in this module, and to see a list of the releases in which each feature is
supported, see the Feature Information Table at the end of this document.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support.
To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Feature Overview
Telco service providers use data communications networks (DCNs) to provide communications between
network management applications (also called operations support systems or OSSs) and network elements.
The telco DCNs use the X.25 protocol (or a variation of X.25) to send network management information
across the DCN.
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
119
X.25 Dual Serial Line Management
Feature Overview
The figure below shows a typical DCN that uses the BX.25 protocol developed by Bell Communications
Research (now Telcordia Technologies). The Lucent 5ESS switch in this network uses the BX.25 protocol
for monitoring, provisioning and collecting billing data.
Figure 19
Network Management Application Monitors Lucent 5ESS Switch over Datakit Network
The Datakit node provides the communications front end to a network management application and
provides two links, SCC0 and SCC1, for link redundancy. One link is active and passes data across the
network; the other remains in standby mode.
The Datakit node acts as a transport, so that to the network management application and the Lucent 5ESS
switch, the node looks like it has two individual circuits. The network management application host is
supplying leads on both interfaces but ignoring Set Asynchronous Balanced Mode (SABM) messages on
the standby interface. If communication is lost on the active interface, the network management application
host responds to the SABM messages on the standby interface and it becomes the active interface.
In the past, incumbent local exchange carriers (ILECs) have built either Lucent Datakit or X.25 networks to
carry the network management data. Large ILEC customers are currently replacing the Lucent Datakit
portion of the networks with Cisco IP core routers in their DCN. The figure below shows a typical
migration path using X.25 over TCP/IP (XOT) and the Cisco Serial Tunneling (STUN) features.
Figure 20
Network Management Application Monitors Lucent 5ESS Switch Using XOT and STUN
Although the solution shown in the figure above eliminates some of the Lucent Datakit network elements
in ILEC networks, the network still requires a Lucent Datakit node as a front end to the network
management application from the Lucent 5ESS switch.
Additionally, competitive local exchange carriers (CLECs) do not have DCNs or have very limited ones.
Furthermore, the CLECs are not interested in purchasing the legacy Lucent Datakit solution shown in the
first figure above, nor do they want to install a network management application with a Lucent Datakit
front end as shown in the second figure above.
Both the CLECs and the ILECs want the DCN based on IP intranet technologies shown in the figure below.
Figure 21
Network Management Application Monitors Lucent 5ESS Switch over IP Network
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Benefits
Supported Standards and MIBs and RFCs
As the figure above shows, Cisco offers solutions that allow telco service providers to reduce operating
costs, translate and migrate existing X.25-based DCNs to IP-based DCNs, and bridge traditional telephony
operations to newer ones. The X.25 Dual Serial Line Management feature is a part of the Cisco IOS Telco
Feature Set, a bundle of applications specific to the DCN environment. Specifically, this feature supports
X.25-to-TCP protocol translation, and provides dual serial interfaces to preserve the redundancy and
monitoring capability available from the SCC0 and SCC1 links on the Lucent 5ESS switch in the DCN
network.
•
•
•
Benefits, page 121
Restrictions, page 121
Related Documents, page 121
Benefits
The X.25 Dual Serial Line Management feature provides the following benefits:
•
•
Preserves the redundancy and monitoring capability available from the SCC0 and SCC1 links on the
Lucent 5ESS switch in the DCN network.
Allows telco service providers to reduce operating costs by migrating existing X.25-based DCNs to
IP-based DCNs.
Additionally, the Cisco IOS translate tcp command has been updated with the dynamic keyword for PVC
options. The dynamic keyword provides a backup facility for PVC applications. Dynamic PVCs can be
made part of an active backup configuration by using the dual serial line management feature.
Restrictions
The X.25 Dual Serial Line Management feature is used in DCN networks utilizing the Lucent 5ESS switch
and running the X.25 protocol.
Related Documents
The chapter " Configuring X.25 and LAPB " in the Cisco IOS Wide-Area Networking Configuration Guide
describes how to configure X.25.
The Cisco protocol translation feature is described in the Configuring Protocol Translation and Virtual
Asynchronous Devices " chapter of the Cisco IOS Terminal Services Configuration Guide.
The translate command used for protocol translation is described in the Cisco IOS Terminal Services
Command Reference.
The section "Switch Monitoring Networks: Cisco X.25 BAI OSS Connectivity Solution" in the Cisco
Network Solutions for the Telco DCN: Telephone Switch Environments white paper provides tasks and
examples for configuring a backup interface using dual serial lines in a telco DCN.
The " X.25 Record Boundary Preservation for Data Communications Networks " chapter of the Wide-Area
Networking Configuration Guide provides related information about X.25 record boundary preservation.
Supported Standards and MIBs and RFCs
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
121
Configuring X.25 Dual Serial Line Management
Configuration Tasks
Standards
None
MIBs
None
To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB
Locator found at the following URL:
http://www.cisco.com/go/mibs
RFCs
None
Configuration Tasks
•
•
•
•
Configuring X.25 Dual Serial Line Management, page 122
Verifying X.25 Dual Serial Line Management, page 123
Troubleshooting Tips, page 124
Monitoring and Maintaining X.25 Dual Serial Line Management, page 124
Configuring X.25 Dual Serial Line Management
To configure the X.25 Dual Serial Line Management feature, you must configure dual serial lines running
the X.25 protocol, and activate a backup function on one of the interfaces. To enter these configurations,
use the following commands beginning in global configuration mode:
SUMMARY STEPS
1. Router(config)# interface serial x / y
2. Router(config-if)# backup active interface serial x / y
3. Router(config-if)# encapsulation x25 dce
4. Router(config-if)# x25 address address
DETAILED STEPS
Command or Action
Purpose
Step 1 Router(config)# interface serial x / y
Begins interface configuration on a serial interface (serial1/6, for example,
which could be the primary interface).
Step 2 Router(config-if)# backup active interface
serial x / y
Assigns a serial interface (serial 1/7, for example) as backup or standby,
for the primary serial interface.
Step 3 Router(config-if)# encapsulation x25 dce
Specifies operation of a serial interface as an X.25 DCE device.
Step 4 Router(config-if)# x25 address address
(Optional) Sets the X.121 address on the interface.
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Verifying X.25 Dual Serial Line Management
Configuration Tasks
Refer to the documents listed in the Related Documents, page 121 section for additional configuration
information. The section X.25 Dual Serial Line Management Configuration Example, page 124 also lists
commands that you might enter to configure X.25 and X.25-to-TCP protocol translation.
Verifying X.25 Dual Serial Line Management
The verification process described in this section is based on the following configuration:
!
interface Serial0/0
description connects to X.25 switch
ip address 10.10.0.15 255.255.255.0
encapsulation x25 dce
backup active interface Serial0/1
x25 ltc 10
clockrate 64000
To verify correct operation of the X.25 Dual Serial Line Management feature, perform the following steps
in EXEC mode:
SUMMARY STEPS
1. Use the show backup command to display which interface is the active backup:
2. Use the show interfaces command to monitor the serial interfaces. In the following display, serial
interface 0/1 is up (active), and its backup interface is serial interface 0/0:
DETAILED STEPS
Step 1
Use the show backup command to display which interface is the active backup:
Example:
Router# show backup
Primary Interface
Secondary Interface
----------------------------------Serial0/0
Serial0/1
Step 2
Status
-----active backup
Use the show interfaces command to monitor the serial interfaces. In the following display, serial interface 0/1 is up
(active), and its backup interface is serial interface 0/0:
Example:
Router# show interfaces s0/1
Serial0/1 is up, line protocol is up
Hardware is PowerQUICC Serial
Description: connects to X.25 switch
Internet address is 10.10.0.30/24
Backup interface Serial0/0, failure delay 0 sec, secondary disable
delay 0 sec,
kickin load not set, kickout load not set
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation X25, loopback not set
X.25 DCE, address 3034, state R1, modulo 8, timer 0
Defaults: idle VC timeout 0
cisco encapsulation
input/output window sizes 2/2, packet sizes 128/128
Timers: T10 60, T11 180, T12 60, T13 60
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
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Troubleshooting Tips
X.25 Dual Serial Line Management Configuration Example
Channels: Incoming-only none, Two-way 10-1024, Outgoing-only none
RESTARTs 2/0 CALLs 4+0/2+0/0+0 DIAGs 0/0
LAPB DCE, state CONNECT, modulo 8, k 7, N1 12056, N2 20
T1 3000, T2 0, interface outage (partial T3) 0, T4 0
VS 1, VR 1, tx NR 1, Remote VR 1, Retransmissions 0
Queues: U/S frames 0, I frames 0, unack. 0, reTx 0
IFRAMEs 130/130 RNRs 0/0 REJs 0/0 SABM/Es 2/1 FRMRs 0/0 DISCs 0/0
Last input never, output 1w3d, output hang never
Last clearing of "show interface" counters 2w2d
Queueing strategy: fifo
Output queue 0/40, 0 drops; input queue 0/75, 0 drops
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
242 packets input, 4224 bytes, 0 no buffer
Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
2 input errors, 0 CRC, 2 frame, 0 overrun, 0 ignored, 0 abort
183 packets output, 1337 bytes, 0 underruns
0 output errors, 0 collisions, 131 interface resets
0 output buffer failures, 0 output buffers swapped out
5 carrier transitions
DCD=up DSR=up DTR=up RTS=up CTS=up
Troubleshooting Tips
To troubleshoot operation of the X.25 Dual Serial Line Management feature, use the debug backup
privileged EXEC command.
Monitoring and Maintaining X.25 Dual Serial Line Management
To monitor and maintain the X.25 Dual Serial Line Management feature, use the commands and steps
listed in the Verifying X.25 Dual Serial Line Management, page 123 section.
X.25 Dual Serial Line Management Configuration Example
In the following example, dual serial lines (serial 1/6 and 1/7) are configured for the X.25 protocol. Serial
interface 1/6 is configured as the primary interface, and serial interface 1/7 is configured as the backup
interface. X.25-to-TCP protocol translation is also configured.
interface Serial1/6
description SCC0
backup active interface serial 1/7
encapsulation x25 dce
x25 address 66666666
x25 ltc 8
x25 ips 256
x25 ops 256
clockrate 9600
!
interface Serial1/7
description SCC1
encapsulation x25 dce
x25 address 66666666
x25 ltc 8
x25 ips 256
x25 ops 256
clockrate 9600
!
x25 route ^66666666 interface Serial1/6
x25 route ^66666666 interface Serial1/7
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
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X.25 Dual Serial Line Management
Glossary
!
translate
translate
translate
translate
translate
translate
translate
tcp
tcp
tcp
tcp
tcp
tcp
tcp
172.20.21.188
172.20.21.188
172.20.21.188
172.20.21.188
172.20.21.188
172.20.21.188
172.20.21.188
port
port
port
port
port
port
port
1025
1026
1027
1028
1029
1030
1031
x25
x25
x25
x25
x25
x25
x25
66666666
66666666
66666666
66666666
66666666
66666666
66666666
pvc
pvc
pvc
pvc
pvc
pvc
pvc
1
2
3
4
5
6
7
dynamic
dynamic
dynamic
dynamic
dynamic
dynamic
dynamic
max-users
max-users
max-users
max-users
max-users
max-users
max-users
1
1
1
1
1
1
1
Glossary
data communications network --See DCN.
DCN --data communications network. An out-of-band network that provides connectivity between network
elements and their respective operations support system (OSS). Its primary function is enabling the
surveillance and the status of a telco network, yet it also facilitates network operations and management
functions such as provisioning, billing, planning, and service assurance.
CLEC --competitive local exchange carrier. Company that builds and operates communication networks in
metropolitan areas and provides its customers with an alternative to the local telephone company.
competitive local exchange carrier --See CLEC.
ILEC -- incumbent local exchange carrier. The local telephone company that controls the cable that makes
up the telephone network.
incumbent local exchange carrier --See ILEC.
Lucent 5ESS switch --A Class 5 local telephony switch that connects a local subscriber to a telephone
network.
network element --A single piece of telecommunications equipment used to perform a function or service
integral to the underlying network.
network management application --A application for managing elements in a service providers’ network.
For a Class 5 local telephony switch, the applications are used monitor the switch, provision the switch,
collect call detail records, and collect traffic data. Examples of these applications include an OSS such as
Lucent’s Network Fault Management (NFM) application and Telcordia Technologies’ Network Monitoring
and Assurance (NMA) System.
operations support system --See OSS.
OSS --operations support system. DCN network management and operations applications.
SABM --Set Asynchronous Balanced Mode. Link Access Procedure, Balanced (LAPB) data link layer
message that sets the operational mode of a link.
Set Asynchronous Balanced Mode --See SABM.
telco --Abbreviated form of the two words "telephone company."
X.25 protocol --ITU-T standard that defines how connections between data terminal equipment and data
communications equipment are maintained for remote terminal access and computer communications in a
network.
Cisco and the Cisco Logo are trademarks of Cisco Systems, Inc. and/or its affiliates in the U.S. and other
countries. A listing of Cisco's trademarks can be found at www.cisco.com/go/trademarks. Third party
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
125
X.25 Dual Serial Line Management
trademarks mentioned are the property of their respective owners. The use of the word partner does not
imply a partnership relationship between Cisco and any other company. (1005R)
Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be
actual addresses and phone numbers. Any examples, command display output, network topology diagrams,
and other figures included in the document are shown for illustrative purposes only. Any use of actual IP
addresses or phone numbers in illustrative content is unintentional and coincidental.
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
126
X.25 over TCP Profiles
Feature History
Release
Modification
12.2(8)T
This feature was introduced.
This document describes the X.25 over TCP Profiles feature in Cisco IOS Release 12.2(8)T. It includes
the following sections:
•
•
•
•
•
•
•
•
Finding Feature Information, page 127
Feature Overview, page 127
Supported Platforms, page 130
Supported Standards and MIBs and RFCs, page 131
Prerequisites, page 131
Configuration Tasks, page 132
Configuration Examples, page 133
Glossary, page 135
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest feature
information and caveats, see the release notes for your platform and software release. To find information
about the features documented in this module, and to see a list of the releases in which each feature is
supported, see the Feature Information Table at the end of this document.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support.
To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Feature Overview
Cisco’s X.25 over TCP (XOT) service was originally developed as an X.25 class of service that was only
designed to switch X.25 traffic across an IP network. This functionality allowed network administrators to
connect X.25 devices across the rich connectivity and media features available to IP traffic. XOT uses a set
of default parameters to make this type of network easy to design.
When XOT’s capabilities were enhanced to support packet assembler/disassembler (PAD) traffic on an
XOT session, network designers saw a need to be able to configure parameters for increased flexibility. For
instance, because XOT does not have any physical interfaces that an administrator can configure, PAD over
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X.25 over TCP Profiles Functional Description
XOT Access Groups
XOT sessions cannot be configured with interface map or facility commands to establish a PAD connection
using nondefault values.
The introduction of X.25 profiles for XOT allows the network designer the added flexibility to control the
X.25 class services of XOT for PAD and XOT switching usage.
Another important aspect of this feature is that it affords you to associate access lists with XOT
connections, enabling you to apply security on the basis of IP addresses and to have a unique X.25
configuration for specified IP addresses.
•
•
•
•
X.25 over TCP Profiles Functional Description, page 128
Benefits, page 129
Restrictions, page 130
Related Documents, page 130
X.25 over TCP Profiles Functional Description
•
•
XOT Access Groups, page 128
X.25 Profiles for XOT, page 129
XOT Access Groups
The X.25 over TCP Profiles feature introduces the xot access-group command, which allows you to create
XOT access groups by associating IP access lists with XOT. An access list provides a pass or fail indicator
of whether a particular IP address is authorized.
Only standard IP access lists are supported. Standard IP access lists use the remote address, which can be
either a source or destination address, depending on where a call originated. For outgoing XOT calls, the
destination IP address is tested against the access lists. For incoming XOT calls, the source IP address is
tested.
The XOT access groups are sorted by access-group number. When a new XOT connection is made, the IP
address is tested against the access list of the first access group. If the IP address does not match the first
list, the second list is tested, and so on.
Deleting an access list while it is still associated with XOT will cause the access list to be skipped when a
new XOT connection is evaluated. If the access list has been deleted and is being recreated, any XOT
access not yet permitted (because the commands have not been configured) will be denied.
A nonexistent access list will deny all access in the same way that an access list configured to "deny all"
will. The result is that a call fails to match that access list and moves on to the next XOT access-group
entry. If the deleted access list is the last one on the access-group list, then the call is rejected.
The xot access-group command disables the legacy XOT behavior and enables the new XOT access
behavior. If you enter the xot access-group command after the legacy XOT context has been created, the
message "Active connection(s) will terminate [confirm]" will be displayed if any XOT connections are
active. If the message is confirmed, any active XOT connections using the legacy context will be detached
and the legacy context will be deleted.
Deleting an XOT access group by entering the no xot access-group command will also cause the message
"Active connection(s) will terminate [confirm]" to be displayed if any connections are active. Confirming
the message will cause active connections using the access list to be detached and the associated XOT
context to be deleted.
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Benefits
X.25 Profiles for XOT
X.25 Profiles for XOT
XOT access groups can be associated with X.25 profiles. By this means, the IP addresses specified in the
access list can have a unique X.25 configuration. An access group can be associated with one X.25 profile.
If an access group is not associated with an X.25 profile, then the XOT connections associated with the
access group will use the default X.25 configuration.
An X.25 profile must already have been created and must specify a data exchange equipment (DXE) station
type before it can be associated with an XOT access group. An X.25 profile can be associated with multiple
access groups.
The station type of a profile cannot be changed once the profile has been created.
An X.25 profile cannot be deleted as long as it is associated with one or more XOT access groups.
•
•
Application of X.25 Profiles on XOT Switched Virtual Circuits, page 129
Application of X.25 Profiles on Remote Switched XOT Permanent Virtual Circuits, page 129
Application of X.25 Profiles on XOT Switched Virtual Circuits
The X.25 parameter settings will be applied to incoming or an outgoing XOT switched virtual circuits
(SVCs) according to the following rules:
1 If one or more access lists are applied to XOT, an XOT call will be rejected unless it matches at least
one of the access lists.
2 The first access list that permits the XOT connection defines the X.25 settings that apply to the XOT
connection. If an X.25 profile was associated with the first qualifying access list, the X.25 settings from
that profile are used. If an X.25 profile was not associated with the qualifying access list, the default X.
25 settings are used.
3 If no access lists are applied to XOT, the default X.25 settings are used.
Application of X.25 Profiles on Remote Switched XOT Permanent Virtual Circuits
The X.25 parameter settings will be applied to remote switched XOT permanent virtual circuits (PVCs)
according to the following rules:
1 If the destination of the XOT PVC does not pass any of the access lists because the access lists have not
been defined, the PVC setup will be retried every 20 seconds until the access list is defined.
2 The PVC setup retry will be canceled if the XOT PVC is deleted.
3 The first access list that includes the destination of the XOT PVC defines the X.25 settings that apply to
the XOT PVC setup. If an X.25 profile was associated with the qualifying access list, the X.25 settings
from that profile are used. If an X.25 profile was not associated with the qualifying access list, the
default X.25 settings are used.
Benefits
The X.25 over TCP Profiles feature
•
•
•
Enables you to apply X.25 profiles to XOT connections so you can configure the X.25 parameters for
use by the XOT service.
Allows a Cisco router to have multiple X.25 configurations that can be used for XOT connection.
Allows IP access lists to be associated with XOT, enabling you to apply security on the basis of IP
addresses.
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
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Restrictions
Supported Platforms
•
Allows the IP addresses specified in the access list to have a unique X.25 configuration.
•
An X.25 profile must already have been created and must specify a DXE station type before it can be
referenced by the XOT command. To create an X.25 profile with a DXE station type, use the x25
profile command with the dxe keyword in global configuration mode.
Closed user group (CUG) service cannot be configured for XOT. CUG behavior is defined to occur at
the boundary between user and network. XOT connections are defined as internetwork connections.
The CUG facility in a switched Call or Call Confirm packet can only be passed transparently over
XOT.
Named and extended access lists are not supported by XOT access groups.
LAPB parameters do not apply to XOT and are ignored if configured under an X.25 profile applied to
XOT connections. For information about why LAPB parameters do not apply to XOT, see RFC 1613,
Cisco Systems X.25 over TCP (XOT) .
The x25 subscribe flow-control command with the never keyword should not be configured in an X.
25 profile that will be used for XOT connections. The never keyword means that negotiation of flowcontrol parameters is disabled and that flow-control parameters will not be included with call setup
packets and will not be permitted on inbound packets. Because XOT always sends window and packet
size facilities in call setup packets, the application of the x25 subscribe flow-control never command
to XOT services will cause calls to fail.
Restrictions
•
•
•
•
Related Documents
For more information about configuring X.25, see the following documents:
•
•
The chapter "Configuring X.25" in the Cisco IOS Wide-Area Networking Configuration Guide ,
Release 12.2
The chapter "X.25 Commands" in the Cisco IOS Wide-Area Networking Command Reference ,
Release 12.2
For information about configuring IP access lists, see the following documents:
•
•
The chapter "Configuring IP Services" in the Cisco IOS IP Configuration Guide , Release 12.2.
The chapter "IP Services Commands" in the Cisco IOS IP Command Reference, Volume 1 of 3:
Addressing and Services , Release 12.2.
Supported Platforms
•
•
•
•
•
•
•
•
•
Cisco 805 Serial Router
Cisco 1400 series
Cisco 1600 series
Cisco 1751
Cisco 2600 series
Cisco 3600 series
Cisco 3725
Cisco 3745
Cisco 7100 series
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
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X.25 over TCP Profiles
Supported Standards and MIBs and RFCs
•
•
•
Cisco 7200 series
Cisco 7500 series
Cisco MC3810
XOT is available on any Cisco router that runs Cisco IOS software and supports X.25.
Determining Platform Support Through Feature Navigator
Cisco IOS software is packaged in feature sets that support specific platforms. To get updated information
regarding platform support for this feature, access Feature Navigator. Feature Navigator dynamically
updates the list of supported platforms as new platform support is added for the feature.
Feature Navigator is a web-based tool that enables you to quickly determine which Cisco IOS software
images support a specific set of features and which features are supported in a specific Cisco IOS image.
To access Feature Navigator, you must have an account on Cisco.com. If you have forgotten or lost your
account information, send a blank e-mail to cco-locksmith@cisco.com. An automatic check will verify that
your e-mail address is registered with Cisco.com. If the check is successful, account details with a new
random password will be e-mailed to you. Qualified users can establish an account on Cisco.com by
following the directions at http://www.cisco.com/register.
Feature Navigator is updated regularly when major Cisco IOS software releases and technology releases
occur. For the most current information, go to the Feature Navigator home page at the following URL:
http://www.cisco.com/go/fn
Supported Standards and MIBs and RFCs
Standards
No new or modified standards are supported by this feature.
MIBs
No new or modified MIBs are supported by this feature.
To obtain lists of supported MIBs by platform and Cisco IOS release, and to download MIB modules, go to
the Cisco MIB website on Cisco.com at the following URL:
http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml
RFCs
RFC 1613, Cisco Systems X.25 over TCP
Prerequisites
The configuration tasks in the following sections assume you know how to configure IP access lists and X.
25 profiles.
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Configuring an XOT Access Group
Configuration Tasks
Configuration Tasks
•
•
•
Configuring an XOT Access Group, page 132
Verifying XOT Access Groups, page 132
Troubleshooting Tips, page 133
Configuring an XOT Access Group
To configure an XOT access group and associate an X.25 profile with it, use the following command in
global configuration mode:
Command
Router(config)# xot access-group
number [profile profile-name]
Purpose
access-list-
Creates an XOT access group.
Verifying XOT Access Groups
To verify XOT access group configuration and performance, perform the tasks in the following steps. For
descriptions of the output fields, see the command pages later in this document.
SUMMARY STEPS
1. Use the show x25 xot command with the access-group keyword to find out which X.25 profiles are
associated with each XOT access group.
2. Use the show x25 profile command to view the X.25 parameter settings that apply to XOT
connections.
3. Use the show x25 context command with the xot keyword to display information about the operational
state of XOT links.
DETAILED STEPS
Step 1
Use the show x25 xot command with the access-group keyword to find out which X.25 profiles are associated with
each XOT access group.
Example:
Router# show x25 xot access-group
xot access-group 1 using built-in default configuration
xot access-group 10 using x.25 profile xot-cisco
xot access-group 55 using x.25 profile xot-sita
Step 2
Use the show x25 profile command to view the X.25 parameter settings that apply to XOT connections.
Example:
Router# show x25 profile
X.25 profile name: XOT-DEFAULT
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Troubleshooting Tips
Configuration Examples
In use by:
Access-group 2
Access-group 10
PROFILE dxe/DTE, address 12345, state R/Inactive, modulo 128, timer 0
Defaults: idle VC timeout 0
input/output window sizes 20/20, packet sizes 256/256
Timers: T20 180, T21 200, T22 180, T23 180
Channels: Incoming-only none, Two-way 1-4095, Outgoing-only none
Step 3
Use the show x25 context command with the xot keyword to display information about the operational state of XOT
links.
Example:
Router# show x25 context xot
XOT Access-group 2
PROFILE mod128 station DXE/DTE, address 2222, state R1, modulo 128, timer 0
Defaults: idle VC timeout 0
input/output window sizes 80/80, packet sizes 256/256
Timers: T20 180, T21 200, T22 180, T23 180
RESTARTs 0/0 CALLs 5+0/7+0/0+0 DIAGs 0/0
XOT Access-group 3
station DXE/DTE, address <none>, state R1, modulo 8, timer 0
Defaults: idle VC timeout 0
input/output window sizes 2/2, packet sizes 128/128
Timers: T20 180, T21 200, T22 180, T23 180
RESTARTs 0/0 CALLs 21+0/50+0/0+0 DIAGs 0/0 D
Troubleshooting Tips
To troubleshoot XOT connections, use the following commands in EXEC mode:
Purpose
Command
Router#
debug x25 events
Router#
show x25 services
Displays information about all X.25 traffic except
data and resource record packets.
Displays information pertaining to X.25 services.
Configuration Examples
• Unrestricted XOT Access with Defined X.25 Parameters for All XOT Connections Example, page
134
• Restricted XOT Access with Default X.25 Parameters for All XOT Connections Example, page 134
• Restricted XOT Access with Multiple X.25 Parameter Configurations Example, page 134
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Unrestricted XOT Access with Defined X.25 Parameters for All XOT Connections Example
Configuration Examples
Unrestricted XOT Access with Defined X.25 Parameters for All XOT
Connections Example
In the following example, an access list is defined to permit all XOT connections. All XOT connections
will use the X.25 configuration defined in the X.25 profile called "NEW-DEFAULT".
! Create a DXE station type profile with any name and configure the X.25 parameters
under ! the named profile
!
x25 profile NEW-DEFAULT dxe
x25 address 12345
x25 modulo 128
x25 win 15
x25 wout 15
x25 ips 256
x25 ops 256
!
! Define an IP standard access list to permit any XOT connection
!
access-list 10 permit any
!
! Apply the access list and X.25 profile to all XOT connections
!
xot access-group 10 profile NEW-DEFAULT
Restricted XOT Access with Default X.25 Parameters for All XOT
Connections Example
In the following example, an X.25 profile is not associated with the access group, so the default X.25
configuration will be applied to all permitted XOT connections.
! Define an IP access list by specifying an IP access list number and access condition
!
access-list 12 permit 192.89.55.0 0.0.0.255
!
! Apply the access list to XOT connections
!
xot access-group 12
Restricted XOT Access with Multiple X.25 Parameter Configurations
Example
In the following example, XOT connections permitted by access list 10 will use the default X.25
configuration. XOT connections permitted by access list 22 will use the X.25 configuration that is defined
in the X.25 profile "TRANSPAC".
! Define the IP access lists by specifying an IP access list number and access condition
!
ip access-list standard 10
permit 10.0.155.9
deny any
ip access-list standard 22
permit 171.69.0.0 0.0.255.255 log
deny any
!
! Apply the default X.25 configuration to XOT connections permitted by access list 10
!
xot access-group 10
!
! Configure an X.25 profile with station type DXE
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X.25 over TCP Profiles
Glossary
!
x25 profile TRANSPAC dxe
x25 modulo 128
x25 win 80
x25 wout 80
x25 default pad
!
! Apply the X.25 profile to XOT connections permitted by access list 22
!
xot access-group 22 profile TRANSPAC
Glossary
access list --List kept by routers to control access to or from the router for a number of services (for
example, to prevent packets with a certain IP address from leaving a particular interface on the router).
CMNS --Connection Mode Network Service. Extends local X.25 switching to a variety of media (Ethernet,
FDDI, Token Ring).
CUG --closed user group. A collection of DTE devices for which the network controls access between
members and between members and nonmembers. A DTE may subscribe to zero, one, or more CUGs. A
DTE that does not subscribe to a CUG is referred to as being in the open part of the network.
DCE --data communications equipment. Devices and connections of a communications network that make
up the network end of the user-to-network interface. The DCE provides a physical connection to the
network, forwards traffic, and provides a clocking signal used to synchronize data transmission between
DCE and DTE devices. Modems and interface cards are examples of DCE.
DTE --data terminal equipment. Device at the user end of a user-network interface that serves as a data
source, destination, or both. DTE connects to a data network through a DCE device (for example, a
modem) and typically uses clocking signals generated by the DCE. DTE includes such devices as
computers, protocol translators, and multiplexers.
HDLC-- high-level data link control. Bit-oriented synchronous data link layer protocol developed by ISO.
HDLC specifies a data encapsulation method on synchronous serial links using frame characters and
checksums.
LAPB --Link Access Procedure, Balanced. Data link layer protocol in the X.25 protocol stack. LAPB is a
bit-oriented protocol derived from high-level data link control (HDLC).
PVC --permanent virtual circuit. Virtual circuit that is permanently established.
SVC --switched virtual circuit. Virtual circuit that is dynamically established on demand and is torn down
when transmission is complete.
X.25 --ITU-T standard that defines how connections between DTE and DCE are maintained for remote
terminal access and computer communications in PDNs. X.25 specifies LAPB, a data-link-layer protocol,
and PLP, a network-layer protocol.
X.25 profile --Bundled X.25 and LAPB commands that can be applied to specific connections.
XOT --X.25 over TCP.
Cisco and the Cisco Logo are trademarks of Cisco Systems, Inc. and/or its affiliates in the U.S. and other
countries. A listing of Cisco's trademarks can be found at www.cisco.com/go/trademarks. Third party
trademarks mentioned are the property of their respective owners. The use of the word partner does not
imply a partnership relationship between Cisco and any other company. (1005R)
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X.25 over TCP Profiles
Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be
actual addresses and phone numbers. Any examples, command display output, network topology diagrams,
and other figures included in the document are shown for illustrative purposes only. Any use of actual IP
addresses or phone numbers in illustrative content is unintentional and coincidental.
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X.25 Record Boundary Preservation for Data
Communications Networks
Feature History
Release
Modification
12.2(8)T
This feature was introduced.
12.4(5th)T
Capability was added for conveying Q-bit data
packets between X.25 and TCP/IP hosts.
This document describes the X.25 Record Boundary Preservation for Data Communications Networks
feature in Cisco IOS Release 12.2(8)T. It includes the following sections:
•
•
•
•
•
•
•
•
Finding Feature Information, page 137
Feature Overview, page 137
Supported Standards and MIBs and RFCs, page 140
Prerequisites, page 141
Configuration Tasks, page 141
Monitoring and Maintaining RBP, page 145
Configuration Examples, page 145
Glossary, page 146
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest feature
information and caveats, see the release notes for your platform and software release. To find information
about the features documented in this module, and to see a list of the releases in which each feature is
supported, see the Feature Information Table at the end of this document.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support.
To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Feature Overview
The X.25 Record Boundary Preservation for Data Communications Networks feature enables hosts using
TCP/IP-based protocols to exchange data with devices that use the X.25 protocol, retaining the logical
record boundaries indicated by use of the X.25 "more data" bit (M-bit).
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When to Use Record Boundary Preservation
Feature Overview
•
•
•
•
•
When to Use Record Boundary Preservation, page 138
How Record Boundary Preservation Works, page 138
Benefits, page 140
Restrictions, page 140
Related Documents, page 140
When to Use Record Boundary Preservation
Before the introduction of the X.25 Record Boundary Preservation for Data Communications Networks
feature, Cisco IOS software provided two methods for enabling the exchange of data between X.25 hosts
and hosts using TCP/IP-based protocols: protocol translation and X.25 over TCP (XOT). Protocol
translation supports a variety of configurations, including translation of a data stream between an X.25
circuit that is using X.29 and a TCP session. The X.29 protocol is an integral part of protocol translation.
One aspect of X.29 is that it is asymmetric and allows the packaging of data into X.25 packets to be
controlled in one direction only. The TCP protocol is stream-oriented, rather than packet-oriented. TCP
does not attach significance to TCP datagram boundaries, and those boundaries can change when a
datagram is retransmitted. This inability to preserve boundaries makes protocol translation appropriate only
for configurations in which the X.25 packet boundary is not significant.
The XOT feature allows X.25 packets to be forwarded over a TCP session. This allows full control over the
X.25 circuit, but the host terminating the TCP session must implement the XOT protocol and the X.25
packet layer protocol.
The Record Boundary Preservation (RBP) feature offers a solution positioned between these two options: it
allows logical message boundaries to be indicated without requiring the TCP host to be aware of X.25
protocol details.
How Record Boundary Preservation Works
The TCP protocol does not attach significance to datagram boundaries, so a protocol must be layered over a
TCP session to convey record boundary information. The Record Boundary Preservation protocol
implements a 6-byte record header that specifies the amount of data following and indicates whether that
data should be considered the final part of a logical record. Table 1 describes the format and contents of the
record header.
Table 8
Record Header Format
Byte
Description
Byte 0
Protocol identifier. This byte must contain the value
0xD7.
Byte 1
Protocol identifier. This byte must contain the value
0x4A.
Bytes 2 and 3
Payload length, in bytes, not including the header.
Byte 2 contains the most significant byte of the
length; byte 3 contains the least significant byte.
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X.25 Record Boundary Preservation for Data Communications Networks
Feature Overview
Byte
Description
Byte 4
"More data" flag. This byte must contain one of the
following values:
•
•
Byte 5
0x00--Indicates that this record is the final part
of the data unit.
0x01--Indicates that this record is not the final
part of the data unit.
Must contain the value 0x00.
When a router configured with RBP receives an X.25 call that matches a configured X.25 RBP map, the
router attempts to open a TCP connection to the specified TCP destination. Each TCP session is mapped to
one X.25 virtual circuit. If the TCP session is established, then X.25 data packets received from the caller
are combined into logical records as indicated by use of the X.25 M-bit, and the contents of the data
packets are forwarded to the TCP destination. The boundaries of these records are preserved by the record
header.
The router will not split an X.25 data packet across multiple records unless the data packet exceeds the
configured maximum record size; however, TCP will segment the data stream at arbitrary byte boundaries
in accordance with TCP specifications.
X.25 data packets with the M-bit set may be combined as long as the resulting record does not exceed the
configured maximum record size or, if a maximum record size was not configured, the maximum datagram
size for the X.25 interface. The "more data" flag in the record header will reflect the value of the M-bit in
the final X.25 data packet. This process of combining packets results in a series of zero or more records
whose "more data" flag is set to the value 1 followed by a record whose "more data" flag is set to 0.
Incoming X.25 calls with the "delivery confirmation" bit (D-bit) set will be answered with the D-bit set.
However, since the router is the endpoint of the X.25 circuit, X.25 data packets will be acknowledged as
soon as their contents have been passed to the TCP connection without waiting for an acknowledgment for
the TCP data, regardless of the value of the D-bit. TCP data will be acknowledged as soon as it has been
converted to X.25 data packets.
The router will not send Receiver Not Ready (RNR) packets on the X.25 circuit; flow control will be
accomplished by withholding acknowledgment.
The following situations will cause the X.25 circuit to be cleared (for an SVC) or reset (for a PVC) and the
TCP connection to be closed: receipt of a data packet with the "qualified" bit (Q-bit) set; receipt of any
packet type other than data, Receiver Ready (RR), or RNR; or a restart or lower-layer reset on the X.25
interface. When the circuit is cleared or reset, any data not yet passed to the TCP connection will be
discarded.
When the router receives the records from the TCP session, it strips the record header and, on the basis of
the information in the record header, reassembles the records into X.25 data packets. The data is interpreted
as a fixed-length header followed by a variable-length payload whose length is specified in the record
header. If the protocol ID or flag field in the header is invalid, the TCP connection will be closed and the X.
25 circuit will be cleared or reset. The payload length may be greater than the X.25 packet size and need
not be a multiple of the X.25 packet size.
A record that has the "more data" flag set will be logically combined with following records until a record
that has the "more data" flag cleared is received. This process results in a sequence of maximum-sized X.25
data packets, each with the M-bit set, followed by an X.25 data packet containing the remaining data that
does not have the M-bit set. The router will not wait for an entire record to be received before sending a
maximum-size X.25 data packet.
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Benefits
Supported Standards and MIBs and RFCs
As the records are reassembled into X.25 data packets, the packets are forwarded to the corresponding X.25
circuit.
The router will not set the D-bit or Q-bit on X.25 data packets being sent over circuits that are configured
with RBP.
Data received by a router from a TCP session will be buffered while waiting for the other connection to be
established. If the connection attempt fails, the data will be discarded. When a TCP connection is closed,
the X.25 circuit will be cleared or reset, and any data not yet sent on the X.25 circuit will be discarded.
Benefits
The X.25 Record Boundary Preservation for Data Communications Networks feature enables X.25 and
TCP/IP hosts to exchange data while preserving X.25 packet boundaries and without having to carry the
full X.25 protocol over the TCP session.
Restrictions
•
•
•
•
X.25 connections will be supported over leased-line X.25 interfaces only.
Only the contents of the X.25 data packets and the record boundary information defined by the X.25
M-bit are conveyed to the TCP session. The contents of the X.25 call packet are used only to identify
the corresponding x25 map rbp command; information from the call packet is not otherwise
forwarded to the TCP host.
When the X.25 circuit is cleared or reset, the X.25 cause and diagnostic codes are not forwarded to the
TCP host.
The call user data specified in incoming or outgoing calls must not conflict with protocol ID values
recognized by the router.
Related Documents
For more information about configuring X.25 networks, refer to the following documents:
•
•
The chapter "Configuring X.25 and LAPB" in the Cisco IOS Wide-Area Networking Configuration
Guide , Release 12.2
The section "X.25 and LAPB Commands" in the Cisco IOS Wide-Area Networking Command
Reference , Release 12.2
Supported Standards and MIBs and RFCs
Standards
No new or modified standards are supported by this feature.
MIBs
No new or modified MIBs are supported by this feature.
To obtain lists of supported MIBs by platform and Cisco IOS release, and to download MIB modules, go to
the Cisco MIB website on Cisco.com at the following URL:
http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml
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Configuring a PVC to Use RBP for Incoming X.25 Connections
Prerequisites
RFCs
No new or modified RFCs are supported by this feature.
Prerequisites
Documentation of the configuration tasks in this document assumes that you know how to configure X.25
networks.
Configuration Tasks
•
•
•
•
•
Configuring a PVC to Use RBP for Incoming X.25 Connections, page 141
Configuring SVCs to Use RBP for Incoming X.25 Connections, page 141
Configuring a PVC to Use RBP for Incoming TCP Connections, page 142
Configuring SVCs to Use RBP for Incoming TCP Connections, page 143
Verifying Record Boundary Preservation, page 143
Configuring a PVC to Use RBP for Incoming X.25 Connections
To configure the router to establish a TCP session in response to data received on an X.25 PVC and to use
RBP protocol to transfer data between the X.25 host and the TCP session, use the following command in
interface configuration mode:
Purpose
Command
x25 pvc circuit rbp
remote host ip-address port port [packetsize
in-size out-size] [source-interface interface]
[recordsize size] [windowsize in-size out-size]
Router(config-if)#
Configures the router to establish a TCP session in
response to data received on an X.25 PVC and to
use RBP protocol to transfer data between the X.25
host and the TCP session.
•
When a PVC is configured to use RBP, the VC
must be unique. Multiple commands
referencing the same VC (matching logical
channel identifier and interface) are not
permitted.
When the x25 pvc rbp remote command is configured, the router will wait until a data packet is received
on the specified X.25 PVC; in the meantime, the router will acknowledge any X.25 reset packets on the
circuit. When a data packet is received, the router will attempt to establish a TCP connection to the
configured IP address and TCP port, using a dynamically assigned local TCP port number. If the
connection attempt fails, the router will reset the permanent virtual circuit and will wait for another data
packet before attempting to establish the TCP connection. Since this command is associated with a specific
X.25 circuit, at most one connection may be active per command.
Configuring SVCs to Use RBP for Incoming X.25 Connections
To configure the router to establish TCP sessions in response to incoming X.25 calls, and to use RBP to
transfer data between the X.25 circuit and the corresponding TCP session, use the following command in
interface configuration mode:
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Configuring a PVC to Use RBP for Incoming TCP Connections
Configuration Tasks
Command
Router(config-if)# x25 map rbp x121-address
[cud string] remote host ip-address port port
[accept-reverse] [recordsize size] [sourceinterface interface]
Purpose
Configures the router to establish TCP sessions in
response to incoming X.25 calls and to use RBP to
transfer data between the X.25 circuit and the
corresponding TCP session.
When the x25 map rbp remote command is configured, the router will accept an incoming X.25 call if the
destination address matches an X.25 address configured on the interface on which the call is received, and
if the calling address and call user data matches the configured value. When the call is accepted, the router
will attempt to open a TCP connection to the configured IP address and TCP port, using a dynamically
assigned local TCP port number. If the TCP connection cannot be opened, the X.25 call will be cleared.
The number of X.25 calls that may be accepted is limited only by router resources. No information from
the X.25 call packet is provided to the TCP/IP host.
Configuring a PVC to Use RBP for Incoming TCP Connections
To configure the router to accept an incoming TCP connection on a specified TCP port, and to use RBP
over that session to transfer data between the TCP host and an X.25 PVC, use the following command in
interface configuration mode:
Command
Router(config-if)# x25 pvc circuit rbp local
port port [packetsize in-size out-size]
[recordsize size] [windowsize in-size out-size]
Purpose
Configures the router to establish a TCP session to
a specified TCP host and port in response to
incoming data on an X.25 PVC and to use the RBP
protocol over that TCP session to transfer data
between the TCP host and the X.25 PVC.
•
•
The local TCP port number must be unique,
with the exception that the same TCP port
number may be configured once on each of
multiple X.25 interfaces that will not be active
simultaneously; this includes the case in which
one X.25 interface is configured as a backup
interface for another X.25 interface.
When a PVC is configured to use RBP, the VC
must be unique. Multiple commands
referencing the same VC (matching logical
channel identifier and interface) are not
permitted.
When the x25 pvc rbp local command is configured, the router will listen for a TCP connection request to
the configured TCP port. Until the connection request is received, any data packets received on the X.25
PVC will cause the PVC to be reset. When the TCP connection request is received, the connection will be
accepted, and the router will send an X.25 reset packet over the configured X.25 destination circuit. If the
reset packet is not acknowledged, the TCP connection will be closed. Since this command is associated
with a specific X.25 circuit, only one connection may be active per command.
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Configuring SVCs to Use RBP for Incoming TCP Connections
Configuration Tasks
Configuring SVCs to Use RBP for Incoming TCP Connections
To configure the router to establish X.25 circuits in response to incoming TCP connections, and to use RBP
to transfer data between the TCP session and the corresponding X.25 circuit, use the following command in
interface configuration mode:
Command
Purpose
Router(config-if)# x25 map rbp x121-address
[cud string] local port port [cug groupnumber] [packetsize in-size out-size]
[recordsize size] [reverse] [roa name]
[throughput in out] [transit-delay
milliseconds] [windowsize in-size out-size]
Configures the router to establish X.25 circuits in
response to incoming TCP connections on a
specified TCP port and to use RBP to transfer data
between the TCP session and the corresponding X.
25 circuit.
•
The local TCP port number must be unique,
with the exception that the same TCP port
number may be configured once on each of
multiple X.25 interfaces that will not be active
simultaneously; this includes the case in which
one X.25 interface is configured as a backup
interface for another X.25 interface.
When the x25 map rbp local port command is configured, the router will listen for a TCP connection
request to the configured TCP port. When the connection is accepted, the router will place an X.25 call
using the configured X.25 destination interface, destination address, and call user data. If the call is not
successfully completed, the TCP connection will be closed. The number of connections that may be
established to the TCP port is limited only by router resources. No information from the TCP connection is
included in the X.25 call packet sent to the X.25 host.
Verifying Record Boundary Preservation
To verify that RBP connections are configured and performing correctly, complete the following steps.
SUMMARY STEPS
1. Enter the show x25 map command to display information about the configured address maps.
2. Enter the show x25 vc command to display information about configured SVCs and PVCs.
3. Enter the show tcp command to display the status of TCP connections.
DETAILED STEPS
Step 1
Enter the show x25 map command to display information about the configured address maps.
The following is sample output of the show x25 map command for a router that is configured with RBP using the x25
pvc rbp remote command:
Example:
Router# show x25 map
Serial1/0:-> rbp, destination host 10.0.0.33 port 9999
PVC, 1 VC:1/P
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X.25 Record Boundary Preservation for Data Communications Networks
Configuration Tasks
The following is sample output of the show x25 map command for a router that is configured with RBP using the x25
map rbp remote command:
Example:
Router# show x25 map
Serial3/0:12132 -> rbp, destination host 10.0.0.32 port 9999
permanent, 1 VC:1024
The following is sample output of the show x25 map command for a router that is configured with RBP using the x25
pvc rbp local command:
Example:
Router# show x25 map
Serial3/0:<- rbp, listening at port 9999
PVC, 1 VC:2/P
The following is sample output of the show x25 map command for a router that is configured with RBP using the x25
map rbp local command:
Example:
Router# show x25 map
Serial1/0:12131 <- rbp, listening at port 9999
permanent, 1 VC:1
For descriptions of the show x25 map display fields, see the show x25 map command page later in this document.
Step 2
Enter the show x25 vc command to display information about configured SVCs and PVCs.
The following is sample output of the show x25 vc command for a PVC configured with record boundary
preservation:
Example:
Router# show x25 vc
PVC 2, State:D1, Interface:Serial3/0
Started 00:08:08, last input 00:00:01, output 00:00:01
recordsize:1500, connected
local address 10.0.0.1 port 9999; remote address 10.0.0.5 port 11029
deferred ack:1
Window size input:2, output:2
Packet size input:128, output:128
PS:2 PR:2 ACK:1 Remote PR:2 RCNT:1 RNR:no
P/D state timeouts:0 timer (secs):0
data bytes 8000/8000 packets 80/80 Resets 9/0 RNRs 0/0 REJs 0/0 INTs 0/0
For descriptions of the show x25 pvc display fields, see the show x25 vc command page later in this document.
Example:
Step 3
Enter the show tcp command to display the status of TCP connections.
The following is sample output of the show tcp command:
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
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PVC Configured to Use RBP for Incoming X.25 Connections Example
Monitoring and Maintaining RBP
Example:
Router# show tcp
Stand-alone TCP connection from host 10.0.0.5
Connection state is ESTAB, I/O status:1, unread input bytes:0
Local host:10.0.0.1, Local port:9999
Foreign host:10.0.0.5, Foreign port:11003
Enqueued packets for retransmit:0, input:0 mis-ordered:0 (0 bytes)
TCP driver queue size 0, flow controlled FALSE
Event Timers (current time is 0x1D0CF8):
Timer
Starts
Wakeups
Next
Retrans
11
0
0x0
TimeWait
0
0
0x0
AckHold
10
0
0x0
SendWnd
0
0
0x0
KeepAlive
20
0
0x1DF68C
GiveUp
0
0
0x0
PmtuAger
0
0
0x0
DeadWait
0
0
0x0
iss:2946187848 snduna:2946188909 sndnxt:2946188909
sndwnd: 7132
irs:1353667951 rcvnxt:1353669012 rcvwnd:
7132 delrcvwnd: 1060
SRTT:231 ms, RTTO:769 ms, RTV:538 ms, KRTT:0 ms
minRTT:0 ms, maxRTT:300 ms, ACK hold:200 ms
Flags:passive open, retransmission timeout, keepalive running
gen tcbs
Datagrams (max data segment is 1460 bytes):
Rcvd:22 (out of order:0), with data:10, total data bytes:1060
Sent:21 (retransmit:0, fastretransmit:0), with data:10, total data bytes:1060
Monitoring and Maintaining RBP
To monitor RBP, use the following command in privileged EXEC mode:
Command
Router#
Purpose
debug x25
Displays information about X.25 traffic.
Configuration Examples
•
•
•
•
PVC Configured to Use RBP for Incoming X.25 Connections Example, page 145
SVCs Configured to Use RBP for Incoming X.25 Connections Example, page 146
PVC Configured to Use RBP for Incoming TCP Connections Example, page 146
SVCs Configured to Use RBP for Incoming TCP Connections Example, page 146
PVC Configured to Use RBP for Incoming X.25 Connections Example
In the following example, when PVC 1 receives a data packet from the X.25 host, the router will attempt to
establish a TCP connection to port 9999 at the TCP/IP host that has the IP address 10.0.0.1.
Interface Serial1/0
encapsulation x25
x25 pvc 1 rbp remote host 10.0.0.1 port 9999
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
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SVCs Configured to Use RBP for Incoming X.25 Connections Example
Glossary
SVCs Configured to Use RBP for Incoming X.25 Connections Example
In the following example, if serial interface 1/0 receives an X.25 call from 12132, the router will map the
call and open a TCP connection to port number 9999 at the remote TCP/IP host that has the IP address
10.0.0.1.
interface Serial1/0
encapsulation x25 dce
x25 address 12030
x25 map rbp 12132 remote host 10.0.0.1 port 9999
PVC Configured to Use RBP for Incoming TCP Connections Example
In the following example, the router is configured to listen for a TCP connection request on port 9999.
When a TCP connection is established, the router will send an X.25 reset over the configured X.25
destination circuit.
Interface serial2/1
encapsulation x25
x25 pvc 2 rbp local port 9999
SVCs Configured to Use RBP for Incoming TCP Connections Example
In the following example, if the router receives a request for a TCP connection at port 9999, the router will
make an X.25 call with no call user data to address 12131.
interface Serial1/0
encapsulation x25 dce
x25 address 13133
x25 map rbp 12131 local port 9999
Glossary
CUD --call user data. Field in an X.25 data packet that contains encapsulated upper-layer information.
CUG --closed user group. A collection of DTE devices for which the network controls access among
members and between members and nonmembers. A DTE may subscribe to zero, one, or more CUGs. A
DTE that does not subscribe to a CUG is referred to as being in the open part of the network.
D-bit --"delivery confirmation" bit. Data packet flag used to request end-to-end acknowledgment for the
packet.
DCE --data communications equipment. Devices and connections of a communications network that make
up the network end of the user-to-network interface. The DCE provides a physical connection to the
network, forwards traffic, and provides a clocking signal used to synchronize data transmission between
DCE and DTE devices. Modems and interface cards are examples of DCE.
DTE --data terminal equipment. Device at the user end of a user-network interface that serves as a data
source, destination, or both. DTE connects to a data network through a DCE device (for example, a
modem) and typically uses clocking signals generated by the DCE. DTE includes such devices as
computers, protocol translators, and multiplexers.
local acknowledgment --Method whereby a switch acknowledges a received data packet before it has
received acknowledgment of the data from the next hop.
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X.25 Record Boundary Preservation for Data Communications Networks
M-Bit --"more data" bit. Data packet flag that indicates that at least one more data packet is required for
completion of a message of contiguous data.
PVC --permanent virtual circuit. Virtual circuit that is permanently established.
Q-bit--"qualified" bit. Data packet flag that signifies that the packet’s user data is a control signal for the
remote device, not a message for the user.
RBP--record boundary preservation. Protocol that defines a way for hosts using TCP/IP-based protocols to
exchange data with devices that use the X.25 protocol, preserving the logical record boundaries conveyed
by the X.25 M-bit ("more data" bit).
SVC --switched virtual circuit. Virtual circuit that is dynamically established on demand and is torn down
when transmission is complete. SVCs are used in situations in which data transmission is sporadic.
X.121 --ITU-T standard describing an addressing scheme used in X.25 networks. Sometimes called the X.
25 address.
X.25 -- ITU-T standard that defines how connections between DTE and DCE are maintained for remote
terminal access and computer communications in PDNs. X.25 specifies LAPB, a data-link layer protocol,
and PLP, a network layer protocol.
XOT --X.25 over TCP.
Cisco and the Cisco Logo are trademarks of Cisco Systems, Inc. and/or its affiliates in the U.S. and other
countries. A listing of Cisco's trademarks can be found at www.cisco.com/go/trademarks. Third party
trademarks mentioned are the property of their respective owners. The use of the word partner does not
imply a partnership relationship between Cisco and any other company. (1005R)
Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be
actual addresses and phone numbers. Any examples, command display output, network topology diagrams,
and other figures included in the document are shown for illustrative purposes only. Any use of actual IP
addresses or phone numbers in illustrative content is unintentional and coincidental.
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
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SVCs Configured to Use RBP for Incoming TCP Connections Example
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
148
X.25 Suppression of Security Signaling
Facilities
The X.25 Suppression of Security Signaling Facilities feature allows the X.25 Call Redirection/Call
Deflection Notification (CRCDN) and Called Line Address Modified Notification (CLAMN) security
signaling facilities to be disabled (suppressed) in X.25 Call and Call Confirm packets (respectively) sent
by an X.25-class service. This feature may be required when connecting to equipment that implements a
proprietary or nonstandard X.25 service that does not accept X.25 security signaling facilities.
Feature Specifications for the X.25 Suppression of Security Signaling Facilities
Feature History
Release
Modification
12.2(13)T
This feature was introduced.
Supported Platforms
Cisco Catalyst 4000 Gateway, Cisco 800 series,
Cisco 805 router, Cisco 1400 series, Cisco 1600
series, Cisco 1600R series, Cisco 1710 router,
Cisco 2500 series, Cisco 2610 to 2613 series,
Cisco 2620 and 2621 routers, Cisco 2650 and
2651 routers, Cisco 2691 router, Cisco 3620
router, Cisco 3631 router, Cisco 3640 router,
Cisco 3660 router, Cisco 3725 router, Cisco 3745
router, Cisco 5300 series, Cisco 5350 router,
Cisco 5400 series, Cisco 5800 series, Cisco 5850
router, Cisco 7100 series, Cisco 7200 series,
Cisco 7400 series, Cisco 8850-RPM, IGX8400URM, Cisco MC3810 router, Cisco uBR 7200
router
Determining Platform Support Through Cisco Feature Navigator
Cisco IOS software is packaged in feature sets that are supported on specific platforms. To get updated
information regarding platform support for this feature, access Cisco Feature Navigator. Cisco Feature
Navigator dynamically updates the list of supported platforms as new platform support is added for the
feature.
Cisco Feature Navigator is a web-based tool that enables you to quickly determine which Cisco IOS
software images support a specific set of features and which features are supported in a specific Cisco IOS
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
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X.25 Security Facilities Suppression Scenarios
Finding Feature Information
image. You can search by feature or release. Under the release section, you can compare releases side by
side to display both the features unique to each software release and the features in common.
To access Cisco Feature Navigator, you must have an account on Cisco.com. If you have forgotten or lost
your account information, send a blank e-mail to cco-locksmith@cisco.com. An automatic check will
verify that your e-mail address is registered with Cisco.com. If the check is successful, account details
with a new random password will be e-mailed to you. Qualified users can establish an account on
Cisco.com by following the directions found at this URL:
http://www.cisco.com/register http://www.cisco.com/register
Cisco Feature Navigator is updated regularly when major Cisco IOS software releases and technology
releases occur. For the most current information, go to the Cisco Feature Navigator home page at the
following URL:
http://www.cisco.com/go/fn
Availability of Cisco IOS Software Images
Platform support for particular Cisco IOS software releases is dependent on the availability of the
software images for those platforms. Software images for some platforms may be deferred, delayed, or
changed without prior notice. For updated information about platform support and availability of software
images for each Cisco IOS software release, refer to the online release notes or Cisco Feature Navigator.
•
•
•
•
•
Finding Feature Information, page 150
Information About the X.25 Suppression of Security Signaling Facilities Feature, page 150
How to Suppress the X.25 Security Signaling Facilities, page 152
Configuration Example for Suppressing X.25 Security Signaling Facilities, page 154
Additional References, page 154
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest feature
information and caveats, see the release notes for your platform and software release. To find information
about the features documented in this module, and to see a list of the releases in which each feature is
supported, see the Feature Information Table at the end of this document.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support.
To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Information About the X.25 Suppression of Security Signaling
Facilities Feature
•
•
X.25 Security Facilities Suppression Scenarios, page 150
When Suppressing the Security Signaling Facilities Is Necessary, page 151
X.25 Security Facilities Suppression Scenarios
X.25 networks encode security facilities in X.25 Call, Call Confirm, and Clear packets to notify both
stations participating in the setup of a switched virtual circuit (SVC) of events that may result in a station
connecting to an unexpected partner.
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
150
When Suppressing the Security Signaling Facilities Is Necessary
Information About the X.25 Suppression of Security Signaling Facilities Feature
Note
This document refers to Call packets and Call Confirm packets. These names differ from those
standardized by X.25. The standard distinguishes between a Call packet sent by the DTE station (a Call
Request) and one sent by the DCE station (an Incoming Call), and similarly between a Call Confirm packet
sent by the DTE (a Call Accepted) and one sent by the DCE (a Call Connected). The packets are encoded
identically and, in many cases, the processing that X.25 does is identical; however, there are cases where
the behavior is predicated on the station type receiving or sending the packet.
For example, when an X.25 Call is redistributed by a network through a hunt group, a standard
implementation will encode a CRCDN facility in the forwarded call. Thus, the receiver is notified that the
Call packet was redistributed by a hunt group and is notified of the original destination address. A standard
network will also, if such a Call is accepted by a returned Call Confirm packet, encode a CLAMN facility
when forwarding the Call Confirm packet. This encoding notifies the originator that the accepting
destination was reached by distribution through a hunt group, and may also encode the destination address
of the accepting station. Both stations receive notification of what happened so each can decide to either
proceed with the SVC, if the resulting connection is permissible, or to clear the channel if not.
When Suppressing the Security Signaling Facilities Is Necessary
Danger
X.25 security signaling facilities are used to explicitly notify the connecting stations of events that may
raise security issues if they were not signaled. Suppression of these facilities should only be configured
when the attached equipment and network configurations are sufficiently secure that the signaled
information is unnecessary.
There are many X.25 implementations that will not operate as intended if presented with X.25 features or
facilities beyond a narrow set of those that occur most commonly. The security signaling facilities are less
common, and there are a significant number of X.25 implementations that will not proceed with an SVC
that encodes them during Call setup. This can cause connection failures when Cisco equipment is used to
implement an X.25 hunt group. There are two security facilities that the Cisco hunt group feature encodes:
An X.25 Call packet forwarded out from a hunt group has the CRCDN facility encoded in the packet and,
when accepted, the returning X.25 Call Confirm packet has the CLAMN facility encoded in the packet.
Both the originator of the Call packet and the destination it reaches should be notified of the hunt group
event, thus allowing each side to clear the SVC if communication is not permitted by the station’s security
policy. For this reason, the Cisco implementation of hunt groups is designed to signal both stations
participating in the Call setup using the X.25-designated CRCDN and CLAMN facilities. The X.25
Suppression of Security Signaling Facilities feature allows this signaling to be suppressed by the CRCDN
facility in a Call packet. The no x25 security crcdn command introduced in this feature provides this
function, and there are no implications for correct protocol behavior by using it.
X.25 operation can also be modified to suppress a CLAMN facility in X.25 Call Confirm packets when the
no x25 security clamn command is configured to disable that signaling. Configuring suppression of the
CLAMN security signaling facility has an implication for correct protocol behavior: The X.25
Recommendations specify that the CLAMN facility must be present in a Call Confirm packet if that packet
encodes a destination address that is not the null address and that differs from the address encoded in the
Call packet. When X.25 is configured to suppress the encoding of a CLAMN facility, it will also suppress
the encoding of the destination address. That is, when the address block is encoded in the Call Confirm
packet, the destination address will be encoded as the null address (zero digits) because no representation
should be made as to what destination was reached.
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Disabling the X.25 Security Signaling Facilities
How to Suppress the X.25 Security Signaling Facilities
An X.25 profile may also be configured to suppress the X.25 security signaling facilities. This profile can
be useful if the network administrator wants to localize the suppression of these facilities. For example, a
hunt group that switches a connection using X.25 over TCP/IP (XOT) may be configured so that the
security signaling facilities are not transmitted to either hop participating in the Call setup.
As another example, some telephone company data communications networks (telco DCNs) use a
nonstandard X.25 implementation that blends elements of the 1980 and 1984 International
Telecommunication Union Telecommunication Standardization Sector (ITU-T) Recommendations. The
figure below shows a portion of a telco DCN network where X.25 devices, also called CPE, are connected
to Cisco routers and the IP backbone network using serial links.
Figure 22
DCN Network Devices Connected to a Cisco IP Backbone Network
Early equipment in the telco DCN conformed to the ITU-T 1980 X.25 Recommendation, and Cisco
provides support for this standard. However, substantial ITU-T 1984 X.25 Recommendation elements, such
as maximum packet sizes of 2048 and 4096 and X.25 Annex G operation, have since been incorporated
into the DCN. This mix of ITU-T 1980 and 1984 X.25 Recommendations in the telco DCN has resulted in
a design requirement that would allow the CPE to operate according to the ITU-T 1984 X.25
Recommendation, but with a modification that would allow suppressing security signaling facilities
encoded by the Cisco hunt group feature. Because the ITU-T 1980 X.25 Recommendation does not define
these security signaling facilities, the Cisco X.25 implementation can now be configured to suppress them
in the packets where they would otherwise be encoded.
How to Suppress the X.25 Security Signaling Facilities
•
Disabling the X.25 Security Signaling Facilities, page 152
Disabling the X.25 Security Signaling Facilities
To disable the X.25 CLAMN and CRCDN signaling facilities, perform the following steps:
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
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X.25 Suppression of Security Signaling Facilities
How to Suppress the X.25 Security Signaling Facilities
SUMMARY STEPS
1. enable
2. configure {terminal | memory | network}
3. interface serial interface-number
4. encapsulation x25
5. no x25 security crcdn
6. no x25 security clamn
7. exit
DETAILED STEPS
Command or Action
Purpose
Step 1 enable
Enables higher privilege levels, such as privileged EXEC mode.
•
Enter your password if prompted.
Example:
Router> enable
Step 2 configure {terminal | memory | network}
Enters global configuration mode.
Example:
Router# configure terminal
Step 3 interface serial interface-number
Enters interface configuration mode.
Example:
Router(config)#
interface serial 0
Step 4 encapsulation x25
Enables the default X.25 DTE operation mode.
Example:
Router(config-if) encapsulation x25
Step 5 no x25 security crcdn
Disables the CRCDN security signaling facility in X.25 Call packets
transmitted.
Example:
Router(config-if) no x25 security crcdn
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
153
X.25 Suppression of Security Signaling Facilities
Troubleshooting Tips
Command or Action
Purpose
Step 6 no x25 security clamn
Disables the CLAMN security signaling facility in X.25 Call Confirm
packets and suppresses any destination address.
Example:
Router(config-if) no x25 security clamn
Step 7 exit
Ends interface configuration mode.
•
Example:
Enter the exit command once more to exit global configuration
mode.
Router(config-if) exit
•
Troubleshooting Tips, page 154
Troubleshooting Tips
Use the debug x25 EXEC command to determine when the X.25 facilities are present and when they are
suppressed by the configured feature.
Configuration Example for Suppressing X.25 Security
Signaling Facilities
The following example shows how to suppress both the CRCDN and CLAMN security signaling facilities:
interface serial 0
no ip address
encapsulation x25
no x25 security crcdn
no x25 security clamn
Additional References
Related Documents
Related Topic
Document Title
X.25 commands
Cisco IOS Wide-Area Networking Command
Reference , Release 12.2
X.25 configuration tasks
Cisco IOS Wide-Area Networking Configuration
Guide, Release 12.2
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
154
X.25 Suppression of Security Signaling Facilities
Additional References
Standards
Standards9
Title
ITU-T X.25
•
•
•
•
ITU-T 1980 X.25 Recommendation
ITU-T 1984 X.25 Recommendation
ITU-T 1988 X.25 Recommendation
ITU-T 1993 X.25 Recommendation
MIBs
MIB
MIBs Link
None
To obtain lists of supported MIBs by platform and
Cisco IOS release, and to download MIB modules,
go to the Cisco MIB website on Cisco.com at the
following URL:
http://www.cisco.com/public/sw-center/netmgmt/
cmtk/mibs.shtml
To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB
Locator found at the following URL:
http://tools.cisco.com/ITDIT/MIBS/servlet/index
If Cisco MIB Locator does not support the MIB information that you need, you can also obtain a list of
supported MIBs and download MIBs from the Cisco MIBs page at the following URL:
http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml
To access Cisco MIB Locator, you must have an account on Cisco.com. If you have forgotten or lost your
account information, send a blank e-mail to cco-locksmith@cisco.com. An automatic check will verify that
your e-mail address is registered with Cisco.com. If the check is successful, account details with a new
random password will be e-mailed to you. Qualified users can establish an account on Cisco.com by
following the directions found at this URL:
http://www.cisco.com/register
RFCs
RFCs
Title
None
--
9 Not all supported standards are listed.
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
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X.25 Suppression of Security Signaling Facilities
Technical Assistance
Description
Link
Technical Assistance Center (TAC) home page,
containing 30,000 pages of searchable technical
content, including links to products, technologies,
solutions, technical tips, tools, and lots more.
Registered Cisco.com users can log in from this
page to access even more content.
http://www.cisco.com/public/support/tac/
home.shtml
Cisco and the Cisco Logo are trademarks of Cisco Systems, Inc. and/or its affiliates in the U.S. and other
countries. A listing of Cisco's trademarks can be found at www.cisco.com/go/trademarks. Third party
trademarks mentioned are the property of their respective owners. The use of the word partner does not
imply a partnership relationship between Cisco and any other company. (1005R)
Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be
actual addresses and phone numbers. Any examples, command display output, network topology diagrams,
and other figures included in the document are shown for illustrative purposes only. Any use of actual IP
addresses or phone numbers in illustrative content is unintentional and coincidental.
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
156
X.25 Call Confirm Packet Address Control
The X.25 Call Confirm Packet Address Control feature provides options for controlling the source and
destination addresses that are encoded in outgoing Call Confirm packets. You can suppress the addresses
completely or specify that the addresses originally proposed in the received Call packet be encoded in the
Call Confirm packet. This feature may be necessary when connecting to equipment that implements a
nonstandard or proprietary X.25 service.
Finding Support Information for Platforms and Cisco IOS Software Images
Use Cisco Feature Navigator to find information about platform support and Cisco IOS software image
support. Access Cisco Feature Navigator at http://www.cisco.com/go/fn . You must have an account on
Cisco.com. If you do not have an account or have forgotten your username or password, click Cancel at
the login dialog box and follow the instructions that appear.
•
•
•
•
•
•
Finding Feature Information, page 157
Information About X.25 Call Confirm Packet Address Control, page 157
How to Configure X.25 Call Confirm Packet Address Control, page 159
Configuration Examples for X.25 Call Confirm Packet Address Control, page 162
Additional References, page 162
Feature Information for X.25 Call Confirm Packet Address Control, page 163
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest feature
information and caveats, see the release notes for your platform and software release. To find information
about the features documented in this module, and to see a list of the releases in which each feature is
supported, see the Feature Information Table at the end of this document.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support.
To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Information About X.25 Call Confirm Packet Address Control
•
•
•
Address Encoding in X.25 Call Confirm Packets, page 158
X.25 Call Confirm Packet Address Control, page 158
Benefits of X.25 Call Confirm Packet Address Control, page 159
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
157
Address Encoding in X.25 Call Confirm Packets
Information About X.25 Call Confirm Packet Address Control
Address Encoding in X.25 Call Confirm Packets
Note
This document refers to Call packets and Call Confirm packets. These names differ from those
standardized by X.25. The standard distinguishes between a Call packet sent by the data terminal
equipment (DTE) station (a Call Request) and one sent by the data communications equipment (DCE)
station (an Incoming Call), and similarly between a Call Confirm packet sent by the DTE (a Call Accepted)
and one sent by the DCE (a Call Connected). The packets are encoded identically, and in many cases the
processing that X.25 does is identical; however, there are cases where the behavior is predicated on the
station type that is receiving or sending the packet.
An X.25 switched virtual circuit (SVC) is established between two stations through the exchange of a Call
and a Call Confirm packet. The X.25 standards specify that Call packets include source and destination
addresses. Call Confirm packets might also encode source and destination addresses, depending on the
circumstances.When the source address is encoded in a Call Confirm packet, the X.25 standards require
that it be the same address that was specified in the Call packet. When the destination address is encoded in
a Call Confirm packet and is different from the destination address in the Call packet, the newer X.25
standards (those after ITU-T 1980 X.25) require that the reason for the difference be signaled by the
encoding of the Called Line Address Modified Notification (CLAMN) facility.
For example,when an X.25 Call is routed through a configured hunt group, a Call Redirection/Call
Deflection Notification (CRCDN) facility is encoded in the forwarded call along with the original
destination address. This encoding notifies the receiver that the Call packet was redistributed by a hunt
group. If such a Call is accepted by a returned Call Confirm packet, a CLAMN facility and the destination
address of the accepting station will be encoded in the Call Confirm packet. This encoding notifies the
originator that the accepting destination was reached by distribution through a hunt group.
X.25 Call Confirm Packet Address Control
Network devices that implement nonstandard X.25 service may have different requirements for address
encoding in the Call Confirm packet. The no x25 security call-confirm address outcommand enables you
to control the source and destination addresses that are encoded in outgoing Call Confirm packets. You can
suppress the addresses completely, or you can specify that the addresses originally presented in the
received Call packet be encoded unmodified in the Call Confirm packet. When address suppression is
configured, any address block in the Call Confirm packet will specify the null address (zero digits) for the
suppressed addresses.
Caution
X.25 specifies address signaling behavior as a security measure to ensure that connecting devices are given
clear notice of a Call setup that encountered redirection, deflection, or distribution to an alternate
destination. Disabling these security features should be done only when the risks of doing so are understood
and acceptable.
X.25 Call Confirm packet address control can be configured on an interface or in an X.25 profile. When the
feature is configured on an interface, all Call Confirm packets sent over the services that use that interface
will be affected, including SVCs that use a configuration from a subinterface. When the feature is
configured in an X.25 profile, all services using that profile will be affected.
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Benefits of X.25 Call Confirm Packet Address Control
How to Configure X.25 Call Confirm Packet Address Control
Benefits of X.25 Call Confirm Packet Address Control
Users implementing nonstandard X.25 service may have specific requirements for the encoding of source
and destination addresses in Call Confirm packets. The X.25 Call Confirm Packet Address Control feature
enables you to control the source and destination addresses that are encoded in outgoing Call Confirm
packets. This feature allows you to suppress the addresses completely or specify that the addresses
originally proposed in the received Call packet be encoded in the Call Confirm packet.
How to Configure X.25 Call Confirm Packet Address Control
•
•
Configuring X.25 Call Confirm Packet Address Control on an Interface, page 159
Configuring X.25 Call Confirm Packet Address Control in an X.25 Profile, page 160
Configuring X.25 Call Confirm Packet Address Control on an Interface
To suppress the addresses in a Call Confirm packet, or to specify that the addresses presented in the
original Call packet are to be encoded in the Call Confirm packet, perform the following steps:
SUMMARY STEPS
1. enable
2. configure terminal
3. interface serial number
4. encapsulation x25
5. no x25 security call-conf address out source {suppress | unmodified} dest {suppress | unmodified}
6. exit
DETAILED STEPS
Command or Action
Step 1 enable
Purpose
Enables privileged EXEC mode.
•
Enter your password if prompted.
Example:
Router> enable
Step 2 configure terminal
Enters global configuration mode.
Example:
Router# configure terminal
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Configuring X.25 Call Confirm Packet Address Control in an X.25 Profile
Troubleshooting Tips
Command or Action
Purpose
Step 3 interface serial number
Specifies an interface and enters interface configuration
mode.
Example:
Router(config)# interface serial 0
Step 4 encapsulation x25
Enables the default X.25 DTE operation mode.
Example:
Router(config-if)# encapsulation x25
Step 5 no x25 security call-conf address out source {suppress |
unmodified} dest {suppress | unmodified}
Suppresses the addresses in transmitted X.25 Call
Confirm packets or specifies that the addresses
originally received in a Call packet are to be encoded in
the Call Confirm packet.
Example:
Router(config-if)# no x25 security call-conf address
out source suppress dest suppress
Step 6 exit
Returns to global configuration mode.
Example:
Router(config-if)# exit
•
Troubleshooting Tips, page 160
Troubleshooting Tips
Use the debug x25 events command to determine when the source and destination addresses in Call
Confirm packets have been suppressed or configured to remain unmodified from the addresses proposed in
the original Call packet.
Configuring X.25 Call Confirm Packet Address Control in an X.25 Profile
To suppress the addresses in a Call Confirm packet, or to specify that the addresses presented in the
original Call packet are to be encoded in the Call Confirm packet, perform the following steps:
SUMMARY STEPS
1. enable
2. configure terminal
3. x25 profile name {dce | dte | dxe}
4. no x25 security call-conf address out source {suppress | unmodified} dest {suppress | unmodified}
5. exit
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X.25 Call Confirm Packet Address Control
Troubleshooting Tips
DETAILED STEPS
Command or Action
Purpose
Step 1 enable
Enables privileged EXEC mode.
•
Enter your password if prompted.
Example:
Router> enable
Step 2 configure terminal
Enters global configuration mode.
Example:
Router# configure terminal
Step 3 x25 profile name {dce | dte | dxe}
Configures an X.25 profile.
Example:
x25 profile NetworkNodeA dce
Step 4 no x25 security call-conf address out source {suppress |
unmodified} dest {suppress | unmodified}
Suppresses the addresses in transmitted X.25 Call
Confirm packets or specifies that the addresses
originally received in a Call packet are to be encoded
in the Call Confirm packet.
Example:
Router(config-if)# no x25 security call-conf address
out source suppress dest suppress
Step 5 exit
Returns to global configuration mode.
Example:
Router(config-if)# exit
•
Troubleshooting Tips, page 161
Troubleshooting Tips
Use the debug x25 events command to determine when the source and destination addresses in Call
Confirm packets have been suppressed or configured to remain unmodified from the addresses proposed in
the original Call packet.
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Suppressing Addresses in Call Confirm Packets Example
Configuration Examples for X.25 Call Confirm Packet Address Control
Configuration Examples for X.25 Call Confirm Packet Address
Control
•
•
Suppressing Addresses in Call Confirm Packets Example, page 162
Using Addresses from Original Call Packets in the Call Confirm Packets Example, page 162
Suppressing Addresses in Call Confirm Packets Example
The following example shows how to suppress both the source and destination addresses in Call Confirm
packets:
interface serial 0
no ip address
encapsulation x25
no x25 security call-conf address out source suppress dest suppress
Using Addresses from Original Call Packets in the Call Confirm Packets
Example
The following example show how to specify that the addresses presented in the original Call packet are
encoded in the Call Confirm packet:
interface serial 0
no ip address
encapsulation x25
no x25 security call-conf address out source unmodified dest unmodified
Additional References
Related Documents
Related Topic
Document Title
X.25 commands
Cisco IOS Wide-Area Networking Command
Reference , Release 12.3
X.25 configuration tasks and examples
Cisco IOS Wide-Area Networking Configuration
Guide, Release 12.3
Commands and tasks for configuring suppression of X.25 Suppression of Security Signaling Facilities,
CRCDN and CLAMN security signaling facilities
12.2(13)T new feature document
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
162
X.25 Call Confirm Packet Address Control
Feature Information for X.25 Call Confirm Packet Address Control
Standards
Standards
Title
ITU-T X.25
•
•
•
•
ITU-T 1980 X.25 Recommendation
ITU-T 1984 X.25 Recommendation
ITU-T 1988 X.25 Recommendation
ITU-T 1993 X.25 Recommendation
MIBs
MIBs
MIBs Link
None
To locate and download MIBs for selected
platforms, Cisco IOS releases, and feature sets, use
Cisco MIB Locator found at the following URL:
http://www.cisco.com/go/mibs
RFCs
RFCs
Title
None
--
Technical Assistance
Description
Link
Technical Assistance Center (TAC) home page,
http://www.cisco.com/public/support/tac/
containing 30,000 pages of searchable technical
home.shtml
content, including links to products, technologies,
solutions, technical tips, and tools. Registered
Cisco.com users can log in from this page to access
even more content.
Feature Information for X.25 Call Confirm Packet Address
Control
The following table provides release information about the feature or features described in this module.
This table lists only the software release that introduced support for a given feature in a given software
release train. Unless noted otherwise, subsequent releases of that software release train also support that
feature.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support.
To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
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X.25 Call Confirm Packet Address Control
Table 9
Feature Information for X.25 Call Confirm Packet Address Control
Feature Name
Releases
Feature Information
X.25 Call Confirm Packet
Address Control
12.3(2)T
The X.25 Call Confirm Packet
Address Control feature provides
options for controlling the source
and destination addresses that are
encoded in outgoing Call
Confirm packets. You can
suppress the addresses completely
or specify that the addresses
originally proposed in the
received Call packet be encoded
in the Call Confirm packet. This
feature may be necessary when
connecting to equipment that
implements a nonstandard or
proprietary X.25 service.
In Cisco IOS Release 12.3(2)T,
this feature was introduced.
The following commands were
introduced or modified: x25
security call-conf address out .
Cisco and the Cisco Logo are trademarks of Cisco Systems, Inc. and/or its affiliates in the U.S. and other
countries. A listing of Cisco's trademarks can be found at www.cisco.com/go/trademarks. Third party
trademarks mentioned are the property of their respective owners. The use of the word partner does not
imply a partnership relationship between Cisco and any other company. (1005R)
Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be
actual addresses and phone numbers. Any examples, command display output, network topology diagrams,
and other figures included in the document are shown for illustrative purposes only. Any use of actual IP
addresses or phone numbers in illustrative content is unintentional and coincidental.
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
164
X.25 Data Display Trace
The X.25 Data Display Trace feature enhances the Cisco IOS debugging capability for X.25. This feature
enables an authorized user to display the entire X.25-encoded traffic stream, including user data, for those
packets specified by an X.25 debug command.
•
•
•
•
Finding Feature Information, page 165
Displaying the Contents of X.25 Packets, page 165
Additional References, page 167
Feature Information for X.25 Data Display Trace, page 167
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest feature
information and caveats, see the release notes for your platform and software release. To find information
about the features documented in this module, and to see a list of the releases in which each feature is
supported, see the Feature Information Table at the end of this document.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support.
To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Displaying the Contents of X.25 Packets
To augment the reporting of X.25 traffic information to include the contents of the X.25 packets, use the
commands listed in the following task. Note that an entry of the debug x25, debug x25 interface, debug
x25 vc, or debug x25 xot commands will override any prior entry of any of these commands.
Caution
The reported X.25 packet information may contain sensitive data; for example, clear-text account identities
and passwords. The network access policies and router configuration should be controlled appropriately to
address this risk.
Caution
The X.25 debug commands can generate large amounts of debugging output. If logging of debug output to
the router console is enabled (the default condition), this output may fill the console buffer, preventing the
router from processing packets until the contents of the console buffer have been printed.
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X.25 Data Display Trace
Displaying the Contents of X.25 Packets
SUMMARY STEPS
1. enable
2. debug x25 [only | cmns| xot] [events | all] [dump]
3. debug x25 interface {serial-interface | cmns-interface [mac mac-address]} [vc number][events | all]
[dump]
4. debug x25 vc number [events | all] [dump]
5. debug x25 xot [remote ip-address [port number]] [local ip-address [port number]] [events | all]
[dump]
DETAILED STEPS
Command or Action
Step 1 enable
Purpose
Enables privileged EXEC mode.
•
Enter your password if prompted.
Example:
Router> enable
Step 2 debug x25 [only | cmns| xot] [events | all]
[dump]
Displays information about all X.25 traffic or a specific X.25 service
class.
•
Example:
Use the dump keyword to display the contents, including user
data, of X.25 packets.
Router# debug x25 events
Step 3 debug x25 interface {serial-interface | cmnsDisplays information about X.25, Annex G or CMNS contexts or
interface [mac mac-address]} [vc number][events virtual circuits that occur on the identified interface.
| all] [dump]
• CMNS reports may be restricted to packets occurring on the
interface with the specified remote host.
•
Use the dump keyword to display the contents, including user
Example:
data, of X.25 packets.
Router# debug x25 interface serial 0 dump
Step 4 debug x25 vc number [events | all] [dump]
Example:
Displays information about traffic for all virtual circuits that use a
given number.
•
Use the dump keyword to display the contents, including user
data, of X.25 packets.
Router# debug x25 vc 1 events
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X.25 Data Display Trace
Additional References
Command or Action
Purpose
Step 5 debug x25 xot [remote ip-address [port number]] Displays information about traffic to or from a specific X.25 over
TCP (XOT) host.
[local ip-address [port number]] [events | all]
[dump]
• Use the dump keyword to display the contents, including user
data, of X.25 packets.
Example:
Router# debug x25 xot remote 10.0.155.71
port 1998
Additional References
Related Documents
Related Topic
Document Title
X.25 configuration tasks
Cisco IOS Wide-Area Networking Configuration
Guide , Release 12.3
X.25 commands
Cisco IOS Wide-Area Networking Command
Reference , Release 12.3
Standards
Standards
Title
ITU-T 1993 Recommendation X.25
Interface between DTE and DCE for terminals
operating in the packet mode and connected to
public data networks by dedicated circuit
Technical Assistance
Description
Link
Technical Assistance Center (TAC) home page,
http://www.cisco.com/public/support/tac/
containing 30,000 pages of searchable technical
home.shtml
content, including links to products, technologies,
solutions, technical tips, and tools. Registered
Cisco.com users can log in from this page to access
even more content.
Feature Information for X.25 Data Display Trace
The following table provides release information about the feature or features described in this module.
This table lists only the software release that introduced support for a given feature in a given software
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
167
X.25 Data Display Trace
release train. Unless noted otherwise, subsequent releases of that software release train also support that
feature.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support.
To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Table 10
Feature Information for X.25 Data Display Trace
Feature Name
Releases
Feature Information
X.25 Data Display Trace
12.3(2)T
The X.25 Data Display Trace
feature enhances the Cisco IOS
debugging capability for X.25.
This feature enables an
authorized user to display the
entire X.25-encoded traffic
stream, including user data, for
those packets specified by an X.
25 debug command.
In Cisco IOS Release 12.3(2)T,
this feature was introduced
The following commands were
introduced or modified: debug
x25, debug x25 interface, debug
x25 vc.
Cisco and the Cisco Logo are trademarks of Cisco Systems, Inc. and/or its affiliates in the U.S. and other
countries. A listing of Cisco's trademarks can be found at www.cisco.com/go/trademarks. Third party
trademarks mentioned are the property of their respective owners. The use of the word partner does not
imply a partnership relationship between Cisco and any other company. (1005R)
Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be
actual addresses and phone numbers. Any examples, command display output, network topology diagrams,
and other figures included in the document are shown for illustrative purposes only. Any use of actual IP
addresses or phone numbers in illustrative content is unintentional and coincidental.
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
168
X.25 Version Configuration
The X.25 Version Configuration feature introduces the x25 version command. The x25 version command
allows you to specify the International Telecommunication Union Telecommunication Standardization
Sector (ITU-T) X.25 recommendation and corresponding behavior set to be used by an interface or
profile.
Feature History for the X.25 Version Configuration Feature
Release
Modification
12.3(8)T
This feature was introduced.
12.3(9)
This feature was integrated into Cisco IOS
Release 12.3(9).
Finding Support Information for Platforms and Cisco IOS Software Images
Use Cisco Feature Navigator to find information about platform support and Cisco IOS software image
support. Access Cisco Feature Navigator at http://www.cisco.com/go/fn . You must have an account on
Cisco.com. If you do not have an account or have forgotten your username or password, click Cancel at
the login dialog box and follow the instructions that appear.
•
•
•
•
•
Finding Feature Information, page 169
Information About X.25 Version Configuration, page 170
How to Specify the X.25 Version, page 178
Configuration Examples for X.25 Version Configuration, page 180
Additional References, page 183
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest feature
information and caveats, see the release notes for your platform and software release. To find information
about the features documented in this module, and to see a list of the releases in which each feature is
supported, see the Feature Information Table at the end of this document.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support.
To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
169
X.25 Version Configuration
Information About X.25 Version Configuration
Information About X.25 Version Configuration
•
•
•
•
X.25 Version Configuration, page 170
Typical Uses of the x25 version Command, page 170
Description of Cisco IOS X.25 Behavior Sets, page 171
X.25 Facility Support, page 173
X.25 Version Configuration
Cisco IOS X.25 support was designed to conform to the Consultative Committee for International
Telegraph and Telephone (CCITT) 1984 X.25 recommendation, both because it represented the largest set
of X.25 devices deployed at that time and because protocol conformance testing to the 1984 standard was
readily available.
The introduction of the x25 version command allows you to specify alternative X.25 behavior sets as
defined by the 1980, 1988, or 1993 X.25 recommendation. By default, Cisco IOS operates to the CCITT
1984 X.25 recommendation. The X.25 version command can be used to change the version for both X.25class services (for example, X.25 and Connection-Mode Network Service (CMNS)) and X.25 configuration
profiles.
A common use of the X.25 version command is the specification of 1980 X.25 behavior set in order to
suppress the signaling of facilities that are not defined by that recommendation. This functionality benefits
customers with an attached X.25 device that is not capable of correctly handling one or more of the
facilities defined in the subsequent standards.
Note
The Cisco IOS implementations of the 1980, 1988, and 1993 X.25 behavior sets have not been tested for
compliance with the recommendations. For example, configuring an interface with the x25 version 1988
command will not necessarily create an interface that offers an X.25 connection that is in full compliance
with the 1988 recommendation; it only enables select features from the 1988 standard that are supported by
the Cisco IOS X.25 implementation.
Typical Uses of the x25 version Command
The x25 version command is typically used to access functionality that is available in other X.25 behavior
sets and to prevent problems that arise when a network is attached to X.25 devices that use nonstandard or
older behavior sets. The table below describes some common problems that can be solved by specifying a
particular X.25 behavior set.
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Description of Cisco IOS X.25 Behavior Sets
Cisco IOS Implementation of the 1980 X.25 Behavior Set
Table 11
Common Problems That Are Solved by the x25 version Command
Problem
Cause
Solution
Some X.25 hosts reject calls that
include Internetwork Call
Redirection and Deflection
Notification (ICRD) or Called
Line Address Modification
Notification (CLAMN).
X.25 hosts may conform to the
1980 standard, which does not
support these facilities, or the
host may be nonstandard.
Specify the 1980 X.25 behavior
set on the interface or X.25
profile.
An incoming call that includes
The interface defaults to the 1984
Protection QoS facilities (an ITU- X.25 behavior set, which does not
T-specified DTE facility) is
define the Protection QoS facility.
cleared by the Cisco router.
Specify the 1988 or 1993
behavior set on the interface to
allow Protection QoS facilities to
be encoded and passed through
transparently by the router.
Incoming calls requesting a
throughput of 64,000 bits per
second (bps) are rejected while
other calls requesting a
throughput of 48,000 bps are
accepted.
The throughput facility in the
1984 recommendation defines a
maximum value of 48,000 bps.
Specify the 1988 behavior set for
services where you need
throughput facility values up to
64,000 bps, and the 1993
behavior set for services where
you need throughput facility
values up to 2,048,000 bps.
After a packet assembler/
disassembler (PAD) call is
initiated over X.25 over TCP
(XoT), the Call packet is cleared
by the router when the Call
Confirm packet includes a
modified destination address.
The called X.25 address has been
modified on the Call Confirm by
the remote X.25 host without
signaling the fact by also
encoding a CLAMN facility--a
potential security issue.
If the security risks are
acceptable, specify the 1980
behavior set on an X.25 profile
configured for the XoT
connection.
Description of Cisco IOS X.25 Behavior Sets
•
•
•
•
Cisco IOS Implementation of the 1980 X.25 Behavior Set,
Cisco IOS Implementation of the 1984 X.25 Behavior Set,
Cisco IOS Implementation of the 1988 X.25 Behavior Set,
Cisco IOS Implementation of the 1993 X.25 Behavior Set,
page 171
page 172
page 172
page 173
Cisco IOS Implementation of the 1980 X.25 Behavior Set
The 1980 X.25 behavior set differs from the default 1984 behavior set in the following ways:
•
•
Only the facilities and facility value encodings defined by the CCITT 1980 X.25 recommendation will
be accepted on packets received; receipt of a facility encoding not specified by that standard will cause
the packet to be rejected as specified in the 1980 recommendation.
Packets sent will use only the facilities and facility value encodings defined by the CCITT 1980 X.25
recommendation.
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X.25 Version Configuration
Cisco IOS Implementation of the 1984 X.25 Behavior Set
•
•
•
•
•
•
•
•
•
The maximum Data packet size is 1024 bytes of user data. This limit affects configurable packet sizes
(for example, PVCs and interface flow control default values) as well as flow control negotiation for
X.25 switching.
The maximum throughput facility value that can be encoded is 48,000 bps. This limit affects
configurable throughput facility values, as well as truncating larger values when an X.25 Call packet is
switched to the service.
The maximum closed user group (CUG) that can be identified is 99. This limit affects configurable
CUG facility values as well as interoperability for X.25 switching.
The facility block that is used to encode X.25 facilities (for example, in a Call packet) cannot exceed
64 bytes.
The Interrupt packet must have 1 byte of user data.
A Clear packet cannot have an address block encoded.
A Clear Confirm packet cannot have an address block encoded.
A received Call Confirm packet is permitted to have a destination address that differs from the address
encoded in the original Call packet.
The cause and diagnostic codes encoded under various circumstances can differ from the default
behavior.
Cisco IOS Implementation of the 1984 X.25 Behavior Set
The 1984 X.25 behavior set is the default X.25 behavior set used by Cisco IOS software and uses the
following default protocol procedures:
•
•
•
•
•
•
•
•
•
•
•
The 1984 X.25 behavior for both Layer 2 and Layer 3 has been tested for compliance with the NET2
and GOSIP test suites. This does not mean that all elements of the standard are implemented, but the
protocol features implemented and tested were accepted as compliant.
Only the facilities and facility value encodings defined by the CCITT 1984 X.25 recommendation will
be accepted on packets received. Receipt of a facility encoding not specified by that standard will
cause the packet to be rejected as specified in the 1984 recommendation.
Packets sent will use only the facilities and facility value encodings defined by the CCITT 1984 X.25
recommendation.
The maximum Data packet size is 4096 bytes of user data.
The maximum throughput facility value that can be encoded is 48,000 bps. This limit affects
configurable throughput facility values, as well as truncating larger values when an X.25 Call packet is
switched to the service.
The maximum closed user group (CUG) that can be identified is 9999.
The facility block that is used to encode X.25 facilities (for example, in a Call packet) cannot exceed
110 bytes.
The Interrupt packet can encode between 1 and 32 bytes of user data.
A Clear packet may, under certain conditions, encode an address block.
A Clear Confirm packet can encode an empty address block (that is, both address lengths are required
to be 0).
If a received Call Confirm or Clear packet encodes a destination address that differs from the address
encoded in the original Call packet, the Call Confirm or Clear packet is also required to encode a
CLAMN facility to signal the reason.
Cisco IOS Implementation of the 1988 X.25 Behavior Set
The 1988 X.25 behavior set differs from the default 1984 behavior set in the following ways:
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X.25 Facility Support
Cisco IOS Implementation of the 1993 X.25 Behavior Set
•
•
•
•
•
Only the facilities and facility value encodings defined by the CCITT 1988 X.25 recommendation will
be accepted on packets received; receipt of a facility encoding not specified by that standard will cause
the packet to be rejected as specified in the 1988 recommendation.
Packets sent will use only the facilities and facility value encodings defined by the CCITT 1988 X.25
recommendation.
The maximum throughput facility value that can be encoded is 64,000 bps. This limit affects
configurable throughput facility values, and it truncates larger values when an X.25 Call packet is
switched to the service.
A Call, Call Confirm, Clear, or Clear Confirm packet that has the A-bit set is not treated as a bad
General Format Identifier, but A-bit encoded addresses are not otherwise supported.
The cause and diagnostic codes encoded under various circumstances can differ from the default
behavior.
Cisco IOS Implementation of the 1993 X.25 Behavior Set
The 1993 X.25 behavior set differs from the default 1984 behavior set in the following ways:
•
•
•
•
•
•
•
•
The 1993 behavior set is the default for XoT service because it simplifies X.25 switching service
configuration.
Only the facilities and facility value encodings defined by the ITU-T 1993 X.25 recommendation will
be accepted on packets received. Receipt of a facility encoding not specified by that standard will
cause the packet to be rejected as specified in the 1993 recommendation.
Packets sent will use only the facilities and facility value encodings defined by the ITU-T 1993 X.25
recommendation.
The maximum throughput facility value that can be encoded is 2,048,000 bps using the extended
throughput class negotiation facility, or 192,000 bps using the facility defined in the prior standards.
This limit affects configurable throughput facility values, as well as truncating larger values when an
X.25 Call packet is switched to the service.
The Internetwork Call Redirection and Deflection (ICRD) facility can be encoded and decoded.
A Call, Call Confirm, Clear, or Clear Confirm packet may be encoded up to a total length of 259
bytes.
A Call, Call Confirm, Clear, or Clear Confirm packet that has the A-bit set is not treated as a bad
General Format Identifier, but A-bit encoded addresses are not otherwise supported.
The cause and diagnostic codes encoded under various circumstances can differ from the default
behavior.
X.25 Facility Support
The table below lists the X.25 standard facilities and shows which X.25 versions permit those facilities to
be encoded in each packet type. A dash (--) in a cell means that the facility is not permitted by any
standard.
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X.25 Version Configuration
Cisco IOS Implementation of the 1993 X.25 Behavior Set
Table 12
Summary of X.25 Standard Facilities
Facility
Packet
Code
Types in
Which the
Facility May
Be Used
Call Request Incoming
Call
Call
Accepted
Call
Connected
Clear
Request
Clear
Indication
DCE Clear
Confirm
Flow
Control
•
Packet
size
1980 1984
1988 1993
1980 1984
1988 1993
1980 1984
1988 1993
1980 1984
1988 1993
--
--
--
42
•
Windo
w size
1980 1984
1988 1993
1980 1984
1988 1993
1980 1984
1988 1993
1980 1984
1988 1993
--
--
--
43
•
Extend -ed
window
size
--
--
--
--
--
--
D5
--
--
--
02
Throughput
•
Basic
1980 1984
1988 1993
1980 1984
1988 1993
1980 1984
1988 1993
1980 1984
1988 1993
•
Extend
ed
1993
1993
1993
1993
4C
Closed User
Group
•
Basic
1980 1984
1988 1993
1980 1984
1988 1993
--
--
--
--
--
03
•
Extend
ed
1984 1988
1993
1984 1988
1993
--
--
--
--
--
47
•
CUG/O 1984 1988
A basic 1993
1984 1988
1993
--
--
--
--
--
09
•
CUG/O 1984 1988
1993
A
extende
d
1984 1988
1993
--
--
--
--
--
48
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
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X.25 Version Configuration
Cisco IOS Implementation of the 1993 X.25 Behavior Set
Facility
•
Packet
Code
Types in
Which the
Facility May
Be Used
Bilatera 1980 1984
1988 1993
l
1980 1984
1988 1993
--
--
--
--
--
41
Reverse
Charging10
1980 1984
1988 1993
1980 1984
1988 1993
--
--
--
--
--
01
Fast Select
1980 1984
1988 1993
1980 1984
1988 1993
--
--
--
--
--
01
ICRD Status 1993
Selection
--
--
--
--
--
--
01
NUI
Selection
1984 1988
1993
--
1984 1988
199311
--
--
--
--
C6
•
Request 1984 1988
1993
--
1984 1988
1993
--
--
--
--
04
•
Moneta -ry
report
--
--
--
--
1984 1988
1993
1984 1988
1993
C5
•
Segmen -t report
--
--
--
--
1984 1988
1993
1984 1988
1993
C2
•
Duratio -n report
--
--
--
--
1984 1988
1993
1984 1988
1993
C1
Charging
Information
ROA
Selection
•
Basic
1980 1984
1988 1993
--
--
--
--
--
--
44
•
Extend
ed
1984 1988
1993
--
--
--
--
--
--
C4
10 The Reverse Charging, Fast Select and ICRD Status Selection values are encoded as bit fields in the single byte value of this facility code.
11 The NUI Selection facility can be encoded in a Call Accepted packet (for those Recommendations that permit it) only in conjunction with the NUI
Subscription option.
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
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X.25 Version Configuration
Cisco IOS Implementation of the 1993 X.25 Behavior Set
Facility
Packet
Code
Types in
Which the
Facility May
Be Used
Call
Deflection
Selection
--
--
--
--
--
1988 199312 --
D1
Call
Redirection
or Call
Deflection
Notification
199313
1984 1988
1993
--
--
--
--
--
C3
Called Line
Address
Modified
Notification
--
--
1984 1988
199314
1984 1988
1993
1984 1988
1993
1984 1988
199315
--
08
Transit
Delay
1984 1988
1993
1984 1988
1993
--
1984 1988
1993
--
--
--
49
Marker
1980 1984
1988 1993
1980 1984
1988 1993
1980 1984
1988 1993
1980 1984
1988 1993
1980 1984
1988 1993
1980 1984
1988 1993
1980 1984
00
1988 199316
Reserved
--
--
--
--
--
--
--
FF
The table below lists the X.25 ITU-T-Specified DTE facilities and shows which X.25 versions permit those
facilities to be encoded in each packet type. A dash (--) in a cell means that the facility is not permitted by
any standard.
12 A DTE cannot encode both the Call Deflection Selection and Called Line Address Modified Notification facilities in the same Clear Request packet.
13 A Call Redirection or Call Deflection Notification facility can only encode the reason "Calling DTE originated" in a Call Request packet.
14 The Called Line Address Modified Notification facility can only encode the reason "Called DTE originated" in a Call Accepted or Clear Request packet.
15 Both notes 3 and 4 apply
16 The 1988 CCITT Recommendation X.25 Table 29/X.25 indicates that a Marker facility is not permissible in a DCE Clear Confirmation packet, however
that interpretation is not stated in the text of the Recommendation, nor does there seem to be such a restriction in the prior Recommendations. It is
advisable to permit it.
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X.25 Version Configuration
Cisco IOS Implementation of the 1993 X.25 Behavior Set
Table 13
Facility
Summary of Support for X.25 ITU-T-Specified DTE Facilities (X.25 Annex G)
Packet
Code
Types in
Which the
Facility May
Be Used
Call Request Incoming
Call
Call
Accepted
Call
Connected
Clear
Request17
Clear
DCE Clear
IndicationX. Confirm
25 Facility
Support,
page 173
Calling
Address
Extension
1984 1988
1993
1984 1988
1993
--
--
1988 199318 --
--
CB
Called
Address
Extension
1984 1988
1993
1984 1988
1993
1984 1988
1993
1984 1988
1993
1984 1988
1993
1984 1988
1993
--
C9
Minimum
Throughput
Class Qos
•
Basic
1984 1988
1993
1984 1988
1993
--
--
1988
1993X.25
Facility
Support,
page 173
--
--
0A
•
Extend
ed
1993
1993
--
--
1993X.25
Facility
Support,
page 173
--
--
4D
1984 1988
1993
1984 1988
1993
1984 1988
1993
1984 1988
1993
1984 1988
1993X.25
Facility
Support,
page 173
--
--
CA
End-to-End
Transit
Delay QoS
17 The facilities specified for a Clear Request and Clear Indication packet can only be encoded if the virtual circuit is in state P3--that is, when an Incoming
Call has been delivered to the DTE but no Call Accepted packet has been sent to the DCE (for a Clear Request) or received by the DCE (for a Clear
Indication). The facilities specified for a Clear Request packet can only be encoded when the standard X.25 Call Deflection Selection facility is also
encoded (1984 exempted).
18 The facilities specified for a Clear Request packet can only be encoded when the standard X.25 Call Deflection Selection facility is also encoded (1984
exempted).
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Specifying the X.25 Behavior Set to Be Used by an Interface or X.25 Profile
How to Specify the X.25 Version
Facility
Packet
Code
Types in
Which the
Facility May
Be Used
Priority QoS 1988 1993
1988 1993
1988 1993
1988 1993
1988
1993X.25
Facility
Support,
page 173
--
--
D2
Protection
QoS
1988 1993
1988 1993
1988 1993
1988 1993
1988
1993X.25
Facility
Support,
page 173
--
--
D3
Expedited
Data
Negotiation
1984 1988
1993
1984 1988
1993
1984 1988
1993
1984 1988
1993
1984 1988
1993X.25
Facility
Support,
page 173
--
--
0B
How to Specify the X.25 Version
•
•
Specifying the X.25 Behavior Set to Be Used by an Interface or X.25 Profile, page 178
Verifying the X.25 Behavior Set for an Interface or X.25 Profile, page 179
Specifying the X.25 Behavior Set to Be Used by an Interface or X.25 Profile
Perform this task to specify the X.25 behavior set that is to be used by an interface or X.25 profile.
SUMMARY STEPS
1. enable
2. configure terminal
3. interface type number
4. x25 version {1980 | 1984 | 1988 | 1993}
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
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Verifying the X.25 Behavior Set for an Interface or X.25 Profile
How to Specify the X.25 Version
DETAILED STEPS
Command or Action
Purpose
Step 1 enable
Enables privileged EXEC mode.
•
Enter your password if prompted.
Example:
Router> enable
Step 2 configure terminal
Enters global configuration mode.
Example:
Router# configure terminal
Step 3 interface type number
Configures an interface type and enters interface configuration
mode.
or
Example:
Configures an X.25 profile and enters X.25 profile
configuration mode.
Example:
x25 profile name {dce
|
dte
|
dxe}
Example:
Router(config)# interface serial 1
Example:
Router(config)# x25 profile
Step 4 x25 version {1980 | 1984 | 1988 | 1993}
Specifies an X.25 behavior set.
•
Example:
The behavior sets are defined by the CCITT 1980, 1984,
and 1988 and ITU-T 1993 X.25 recommendations.
Router(config-if)# x25 version 1980
Verifying the X.25 Behavior Set for an Interface or X.25 Profile
Perform this task to verify which X.25 behavior set is being used by an interface or X.25 profile.
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
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X.25 Version Configuration
Configuration Examples for X.25 Version Configuration
SUMMARY STEPS
1.
2.
3.
4.
enable
show interfaces [type number]
show x25 profile [name]
show x25 context [xot | interface serial number [dlci number] | cmns-interface-type number [mac
DETAILED STEPS
Command or Action
Purpose
Step 1 enable
Enables privileged EXEC mode.
•
Enter your password if prompted.
Example:
Router> enable
Step 2 show interfaces [type number]
Displays statistics for all interfaces configured on
the router or access server.
Example:
Router# show interfaces serial 0/1
Step 3 show x25 profile [name]
Displays details of the X.25 profiles on your
router.
Example:
Router# show x25 profile profile1
Step 4 show x25 context [xot | interface serial number [dlci number] |
cmns-interface-type number [mac
Displays operating configuration status details of
an X.25 link.
Example:
mac-address
]]
Example:
Router# show x25 context interface serial 1/1
Configuration Examples for X.25 Version Configuration
•
•
•
Specifying the X.25 Version to Be Used by an Interface in a Hunt Group Example, page 181
Specifying the X.25 Version to Be Used by Both Interfaces in a Hunt Group Example, page 181
Verifying the X.25 Version for an Interface or X.25 Profile, page 182
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Specifying the X.25 Version to Be Used by an Interface in a Hunt Group Example
Configuration Examples for X.25 Version Configuration
Specifying the X.25 Version to Be Used by an Interface in a Hunt Group
Example
The X.25 hunt group feature will signal a Call's destination device of the hunt group handling by
forwarding the Call with a Call Redirection or Call Deflection Notification (CRCDN) facility. In addition,
the Call's originating device will be notified by forwarding a Call Confirm reply back with a Called Line
Address Modified Notification (CLAMN) facility.
The following example configures an interface to use the 1980 X.25 behavior set:
Router# configure terminal
Enter configuration commands, one per line.
Router(config)# interface serial 3/2
Router(config-if)# x25 version 1980
Router(config-if)# end
End with CNTL/Z.
This interface, on receipt of a Call packet that is processed through a hunt group, will now suppress the
CLAMN facility on the returned Call Confirm, as demonstrated by the following output of the x25 debug
command:
*14:14:51.899:
*14:14:51.899:
*14:14:51.899:
*14:14:51.899:
*14:14:51.899:
*14:14:51.899:
*14:14:51.899:
*14:14:51.899:
(6): 170091
*14:14:51.899:
*14:14:51.903:
*14:14:51.903:
*14:14:51.903:
*14:14:51.903:
*14:14:51.903:
Serial3/2: X.25 I R1 Call (13) 8 lci 1024
From (6): 170093 To (2): 91
Facilities: (0)
Call User Data (4): 0xCC000000 (ip)
Serial3/3: X.25 O R1 Call (22) 8 lci 1
From (6): 170093 To (6): 170091
Facilities: (7)
Call redirection/deflection notice, reason 0x80 specified by source
Call User Data (4): 0xCC000000 (ip)
Serial3/3: X.25 I R1 Call Confirm (3) 8 lci 1
: X.25 Stripped facility: Called Line Address Modified notice
Serial3/2: X.25 O R1 Call Confirm (9) 8 lci 1024
From (6): 170093 To (2): 91
Facilities: (0)
Specifying the X.25 Version to Be Used by Both Interfaces in a Hunt Group
Example
The following example configures the 1980 X.25 behavior set on both interfaces participating in a hunt
group:
Router# configure terminal
Enter configuration commands, one per line.
Router(config)# interface serial 3/2
Router(config-if)# x25 version 1980
Router(config)# interface serial 3/3
Router(config-if)# x25 version 1980
Router(config-if)# end
End with CNTL/Z.
The interfaces, on receipt of a Call packet that is processed through a hunt group, will now suppress both
the CRCDN facility on the forwarded Call packet and the CLAMN facility on the returned Call Confirm, as
demonstrated by the following output of the x25 debug command:
*14:16:33.167: Serial3/2: X.25 I R1 Call (13) 8 lci 1024
*14:16:33.167:
From (6): 170093 To (2): 91
*14:16:33.167:
Facilities: (0)
*14:16:33.171:
Call User Data (4): 0xCC000000 (ip)
*14:16:33.171:
: X.25 Stripped facility: Call redirection/deflection notice
*14:16:33.171: Serial3/3: X.25 O R1 Call (15) 8 lci 1
*14:16:33.171:
From (6): 170093 To (6): 170091
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
181
Verifying the X.25 Version for an Interface or X.25 Profile
Configuration Examples for X.25 Version Configuration
*14:16:33.171:
Facilities: (0)
*14:16:33.171:
Call User Data (4): 0xCC000000 (ip)
*14:16:33.171: Serial3/3: X.25 I R1 Call Confirm (3) 8 lci 1
*14:16:33.171:
: X.25 Stripped facility: Called Line Address Modified notice
*14:16:33.171: Serial3/2: X.25 O R1 Call Confirm (9) 8 lci 1024
*14:16:33.171:
From (6): 170093 To (2): 91
*14:16:33.171:
Facilities: (0)
Verifying the X.25 Version for an Interface or X.25 Profile
The following examples show output for the commands that can be used to verify X.25 version
configuration.
show interfaces Sample Output: Example
Router# show interfaces serial 1/1
Serial1/1 is up, line protocol is up
Hardware is CD2430 in sync mode
Description: connected to stroll Serial1/1
Internet address is 1.0.0.2/8
MTU 1500 bytes, BW 128 Kbit, DLY 20000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation X25, loopback not set
X.25 DCE, version 1984, address 170092, state R1, modulo 8, timer 0
Defaults: idle VC timeout 0
cisco encapsulation
input/output window sizes 2/2, packet sizes 128/128
Timers: T10 60, T11 180, T12 60, T13 60
Channels: Incoming-only none, Two-way 10-100, Outgoing-only 200-210
RESTARTs 1/0 CALLs 0+0/0+0/0+0 DIAGs 0/0
LAPB DCE, state CONNECT, modulo 8, k 7, N1 12056, N2 20
.
.
.
show x25 profile Sample Output: Example
Router# show x25 profile profile1
X.25 profile name: profile1
PROFILE DTE, version 1993, address <none>, state R/Inactive, modulo 8, timer 0
Defaults: idle VC timeout 0
input/output window sizes 2/2, packet sizes 128/128
Timers: T20 180, T21 200, T22 180, T23 180
Channels: Incoming-only none, Two-way 1-1024, Outgoing-only none
show x25 context Sample Output: Examples
Router# show x25 context interface serial 1/1
X.25 DCE, version 1984, address 170092, state R1, modulo 8, timer 0
Defaults: idle VC timeout 0
cisco encapsulation
input/output window sizes 2/2, packet sizes 128/128
Timers: T10 60, T11 180, T12 60, T13 60
Channels: Incoming-only none, Two-way 10-100, Outgoing-only 200-210
RESTARTs 0/0 CALLs 0+0/0+0/0+0 DIAGs 0/0
LAPB DCE, state CONNECT, modulo 8, k 7, N1 12056, N2 20
T1 3000, T2 0, interface outage (partial T3) 0, T4 0
VS 2, VR 2, tx NR 2, Remote VR 2, Retransmissions 0
Queues: U/S frames 0, I frames 0, unack. 0, reTx 0
IFRAMEs 2/2 RNRs 0/0 REJs 0/0 SABM/Es 1/0 FRMRs 0/0 DISCs 0/0
Router# show x25 context xot
XOT
station DXE/DTE, version 1993, address <none>, state R1, modulo 8
Defaults: idle VC timeout 0
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
182
X.25 Version Configuration
Additional References
input/output window sizes 2/2, packet sizes 128/128
Timers: T20 180, T21 200, T22 180, T23 180
RESTARTs 0/0 CALLs 0+1/0+0/0+0 DIAGs 0/0
Router# show x25 context interface serial 1/0
Serial1/0 DLCI 16
PROFILE dxe/DTE, version 1993, address 2001510, state R1, modulo 8, timer 0
Defaults: idle VC timeout 0
input/output window sizes 2/2, packet sizes 128/128
Timers: T20 180, T21 200, T22 180, T23 180
Channels: Incoming-only none, Two-way 1-4095, Outgoing-only none
RESTARTs 0/0 CALLs 0+0/0+0/0+0 DIAGs 0/0
LAPB dxe/DTE, state CONNECT, modulo 8, k 7, N1 12056, N2 20
T1 3000, T2 0, interface outage (partial T3) 0, T4 0
VS 1, VR 1, tx NR 1, Remote VR 1, Retransmissions 0
Queues: U/S frames 0, I frames 0, unack. 0, reTx 0
IFRAMEs 1/1 RNRs 0/0 REJs 0/0 SABM/Es 1/0 FRMRs 0/0 DISCs 0/0
Additional References
Related Documents
Related Topic
Document Title
X.25 configuration information
Wide-Area Networking Protocols
X.25 commands
Cisco IOS Wide-Area Networking Command
Reference
Information about X.25 facility handling
X.25 Facility Handling
Standards
Standards
Title
CCITT 1980 Recommendation X.25
Interface Between Data Terminal Equipment (DTE)
and Data Circuit-Terminating Equipment (DCE) for
Terminals Operating in the Packet Mode and
Connected to Public Data Networks by Dedicated
Circuit
CCITT 1984 Recommendation X.25
Interface Between Data Terminal Equipment (DTE)
and Data Circuit-Terminating Equipment (DCE) for
Terminals Operating in the Packet Mode and
Connected to Public Data Networks by Dedicated
Circuit
CCITT 1988 Recommendation X.25
Interface Between Data Terminal Equipment (DTE)
and Data Circuit-Terminating Equipment (DCE) for
Terminals Operating in the Packet Mode and
Connected to Public Data Networks by Dedicated
Circuit
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
183
X.25 Version Configuration
Standards
Title
ITU-T 1993 Recommendation X.25
Interface Between Data Terminal Equipment (DTE)
and Data Circuit-Terminating Equipment (DCE) for
Terminals Operating in the Packet Mode and
Connected to Public Data Networks by Dedicated
Circuit
MIBs
MIBs
MIBs Link
None
To locate and download MIBs for selected
platforms, Cisco IOS releases, and feature sets, use
Cisco MIB Locator found at the following URL:
http://www.cisco.com/go/mibs
RFCs
RFCs
Title
None
--
Technical Assistance
Description
Link
Technical Assistance Center (TAC) home page,
http://www.cisco.com/public/support/tac/
containing 30,000 pages of searchable technical
home.shtml
content, including links to products, technologies,
solutions, technical tips, and tools. Registered
Cisco.com users can log in from this page to access
even more content.
Cisco and the Cisco Logo are trademarks of Cisco Systems, Inc. and/or its affiliates in the U.S. and other
countries. A listing of Cisco's trademarks can be found at www.cisco.com/go/trademarks. Third party
trademarks mentioned are the property of their respective owners. The use of the word partner does not
imply a partnership relationship between Cisco and any other company. (1005R)
Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be
actual addresses and phone numbers. Any examples, command display output, network topology diagrams,
and other figures included in the document are shown for illustrative purposes only. Any use of actual IP
addresses or phone numbers in illustrative content is unintentional and coincidental.
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
184
X.25 Station Type for ISDN D-channel Interface
The X.25 Station Type for ISDN D-channel Interface feature permits configuration of the X.25 station
type for the ISDN D-channel interface with the encapsulation x25 command on this interface. This
feature allows the mapping of closed user group (CUG) of the X.25 packets that originates from the pointof-sale devices terminating the ISDN-BRI D-channel interface configured as an X.25 data
communications equipment (DCE) station of Cisco routers with an ISDN BRI interface.
The default encapsulation of the BRI D-channel interface is X.25 encapsulation in data terminal
equipment (DTE) mode. To change the X.25 station type on the ISDN BRI D-channel interface, use the
encapsulation 25 command with the appropriate keyword in the interface configuration mode. If no
keyword is specified, the interface will be configured with X.25 encapsulation in DTE mode.
When a router boots up with the new ISDN BRI interface, the encapsulation will not show up explicitly in
the ISDN BRI D-channel interface configuration although the encapsulation will be set as an X.25 DTE
station, the default for this interface. When the no encapsulation command is issued on the ISDN BRI Dchannel interface, the interface will be set as an X.25 DTE station, the default. This will show up in the
running configuration of the interface as encapsulation x25.
Feature History for X.25 Station Type for ISDN D-channel Interface
Release
Modification
12.3(7)XR
This feature was introduced.
12.3(14)T
This feature was integrated into Cisco IOS
Release 12.3(14)T.
Finding Support Information for Platforms and Cisco IOS Software Images
Use Cisco Feature Navigator to find information about platform support and Cisco IOS software image
support. Access Cisco Feature Navigator at http://www.cisco.com/go/fn . You must have an account on
Cisco.com. If you do not have an account or have forgotten your username or password, click Cancel at
the login dialog box and follow the instructions that appear.
•
•
•
•
•
•
Finding Feature Information, page 186
Prerequisites for X.25 Station Type for ISDN D-channel Interface, page 186
Information About X.25 Station Type for ISDN D-channel Interface, page 186
How to Configure X.25 Encapsulation on ISDN BRI D-channel Interface, page 187
Configuration Examples for X.25 Encapsulation on ISDN BRI D-channel Interface, page 189
Additional References, page 190
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
185
Configuring X.25 on ISDN D-channel Interface
Finding Feature Information
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest feature
information and caveats, see the release notes for your platform and software release. To find information
about the features documented in this module, and to see a list of the releases in which each feature is
supported, see the Feature Information Table at the end of this document.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support.
To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Prerequisites for X.25 Station Type for ISDN D-channel
Interface
•
The BRI interface needs to be configured for X.25 traffic over an ISDN D-channel using the isdn x25
dchannel command in interface configuration mode.
For more details, see the following URL:
http://www.cisco.com/univercd/cc/td/doc/product/software/ios123/123cgcr/dial_r/dia_i2g.htm#1050084
•
The ISDN BRI D-channel interface of the peer that is connected to this interface should be a
complementary station type.
Information About X.25 Station Type for ISDN D-channel
Interface
•
•
Configuring X.25 on ISDN D-channel Interface, page 186
X.25 Closed User Groups, page 187
Configuring X.25 on ISDN D-channel Interface
If the D channel of an ISDN BRI interface will carry X.25 traffic, you need to configure the feature that is
described in the Configuring X.25 on ISDN feature guide.
A BRI is an ISDN interface. It consists of two B channels (B1 and B2) and one D-channel. The B channels
are used to transfer data, voice, and video. The D channel controls the B channels.
ISDN uses the D-channel to carry signal information. ISDN can also use the D-channel in a BRI to carry X.
25 packets. The D-channel has a capacity of 16 kbps; the X.25 over D-channel can use up to 9.6 kbps.
When this feature is configured, a separate X.25-over-D-channel logical interface is created. You can set its
parameters without disrupting the original ISDN interface configuration. The original BRI interface will
continue to represent the D, B1, and B2 channels.
An interface configured for X.25 traffic over the D channel can be used as a primary interface where lowvolume, sporadic, interactive traffic is the normal mode of operation. Supported traffic includes IPX,
AppleTalk, transparent bridging, XNS, DECnet, and IP.
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
186
X.25 Closed User Groups
How to Configure X.25 Encapsulation on ISDN BRI D-channel Interface
For more details on how to configure the X.25 over ISDN D-channel Interface feature, see the following
URL:
http://www.cisco.com/univercd/cc/td/doc/product/software/ios113ed/113ed_cr/dial_c/dcprt10/dcxisdn.htm
X.25 Closed User Groups
A closed user group (CUG) is a collection of DTE devices for which the network controls access between
two members and between a member and a non-member. An X.25 network can support up to 10,000 CUGs
(numbered between 0 and 9999), each of which can have any number of member DTE devices. An
individual DTE becomes a member of a specific network CUG by subscription. The subscription data
includes the local number that the DTE will use to identify the network CUG (which may or may not be the
same as the network number, as determined by network administration and the DTE device’s
requirements), and any restriction that prohibits the DTE from placing a call within the CUG or,
conversely, prohibits the network from presenting a call within the CUG to the DTE.
With the X.25 CUGs feature, the router’s X.25 DCE interfaces can be configured to perform the standard
CUG access controls that are normally associated with a direct attachment to an X.25 network point of
presence (POP). The router’s DCE interface acts as the boundary between the DTE and the network, and
CUG use ensures that only those incoming and outgoing switched virtual circuits (SVCs) consistent with
the configured CUG subscriptions are permitted. X.25 CUG configuration commands on the router are
specified at every POP, and CUG security decisions are made solely from those commands.
The X.25 CUGs feature is used for additional X.25 access protection and security. In a setup where DTE
devices are attached to a public data network (PDN), you can derive a private subnetwork by subscribing
your DTE devices to a set of CUGs, which allows closer control of your DTE devices, such as permitting
or restricting which DTE can talk to other DTE devices and for what particular purpose. For example, a
distinct CUG can be defined to handle each of the different modes of connectivity, such as following:
•
•
•
•
Datagram encapsulation operation between all company sites
Packet assembler/disassembler (PAD) services for customers seeking public information
PAD services for system administration internal access to consoles
Qualified Logical Link Control (QLLC) access restricted to the company financial centers
For more details, see the following URL:
http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/120newft/120t/120t7/x25scugs.htm
How to Configure X.25 Encapsulation on ISDN BRI D-channel
Interface
•
Configuring X.25 Encapsulation on ISDN BRI D-channel Interface, page 187
Configuring X.25 Encapsulation on ISDN BRI D-channel Interface
Note
Use the interface BRI2/0 and isdn x25 dchannelcommands if the configurable interface for X.25 traffic
over ISDN D-channel does not exist.
To configure X.25 encapsulation on ISDN BRI D-channel Interface, perform the following steps.
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X.25 Station Type for ISDN D-channel Interface
How to Configure X.25 Encapsulation on ISDN BRI D-channel Interface
SUMMARY STEPS
1. enable
2. configure terminal
3. interface BRI2/0
4. isdn x25 dchannel
5. interface BRI2/0:0
6. encapsulation X25 dce
7. end
DETAILED STEPS
Command or Action
Step 1 enable
Purpose
Enables privileged EXEC mode.
•
Enter your password if prompted.
Example:
Router> enable
Step 2 configure terminal
Enters global configuration mode.
Example:
Router# configure terminal
Step 3 interface BRI2/0
(Optional) Specifies an ISDN BRI interface.
Note Use this command if the configurable interface for X.25 traffic over ISDN D-
Example:
channel does not exist.
Router# interface BRI2/0
Step 4 isdn x25 dchannel
Example:
(Optional) Creates a configurable interface for X.25 traffic over the ISDN Dchannel.
Note Use this command if the configurable interface for X.25 traffic over ISDN D-
channel does not exist.
Router# isdn x25 dchannel
Step 5 interface BRI2/0:0
Specify an ISDN BRI D-channel interface.
Example:
Router# interface BRI2/0:0
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188
X.25 Encapsulation on an ISDN BRI D-channel Interface Example
Configuration Examples for X.25 Encapsulation on ISDN BRI D-channel Interface
Command or Action
Purpose
Step 6 encapsulation X25 dce
Enables X.25 encapsulation in DCE mode.
Example:
Router# encapsulation X.25 dce
Step 7 end
(Optional) Exits the configuration mode and returns to privileged EXEC mode.
Example:
Router# end
Example
The following example configures the X.25 encapsulation in DCE mode on an BRI interface 2/0:0:
interface BRI2/0:0
ip address 1.1.1.2 255.255.255.0
encapsulation X.25 dce
no ip mroute-cache
X.25 subscribe cug-service
X.25 subscribe local-cug 10 network-cug 100
!
Configuration Examples for X.25 Encapsulation on ISDN BRI
D-channel Interface
•
X.25 Encapsulation on an ISDN BRI D-channel Interface Example, page 189
X.25 Encapsulation on an ISDN BRI D-channel Interface Example
The following example shows X.25 encapsulation configured on interface BRI2/0:
Current configuration: 2275 bytes
!
version 12.3
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname Router
!
boot system flash c1700-voice-mz
enable password cisco
!
memory-size iomem 15
tdm clock bri-auto
voice-card 2
!
no aaa new-model
ip subnet-zero
!
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
189
X.25 Station Type for ISDN D-channel Interface
Additional References
!
!
no ftp-server write-enable
isdn switch-type basic-net3
!
no voice hpi capture buffer
no voice hpi capture destination
!
interface FastEthernet0/0
ip address 10.0.2.199 255.255.255.0
speed 100
!
interface BRI2/0
no ip address
isdn switch-type basic-net3
isdn protocol-emulate network
isdn layer1-emulate network
no isdn outgoing display-ie
isdn x25 static-tei 1
isdn x25 dchannel
isdn skipsend-idverify
!
interface BRI2/0:0
no ip address
encapsulation x25 dce
x25 subscribe cug-service incoming-access outgoing-access
x25 subscribe local-cug 5000 network-cug 55 preferential
!
interface BRI2/1
no ip address
shutdown
isdn switch-type basic-net3
!
ip classless
no ip http server
!
voice-port 2/0
!
voice-port 2/1
!
line con 0
line aux 0
line vty 0 4
login
!
end
Additional References
Related Documents
Related Topic
Document Title
Cisco IOS Release 12.3 Configuration Guides and
Command References
Cisco IOS Release 12.3 Configuration Guides and
Command References
Cisco IOS Dial Technologies Command Reference, "Dial Technologies Commands: isdn all through
Release 12.3
isdn x25" section in Cisco IOS Dial Technologies
Command Reference , Release 12.3
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
190
X.25 Station Type for ISDN D-channel Interface
Standards
Standards
Title
None
--
MIBs
MIBs
•
MIBs Link
To locate and download MIBs for selected
platforms, Cisco IOS releases, and feature sets, use
Cisco MIB Locator found at the following URL:
None
http://www.cisco.com/go/mibs
RFCs
RFCs
Title
None
--
Technical Assistance
Description
Link
Technical Assistance Center (TAC) home page,
http://www.cisco.com/public/support/tac/
containing 30,000 pages of searchable technical
home.shtml
content, including links to products, technologies,
solutions, technical tips, and tools. Registered
Cisco.com users can log in from this page to access
even more content.
Cisco and the Cisco Logo are trademarks of Cisco Systems, Inc. and/or its affiliates in the U.S. and other
countries. A listing of Cisco's trademarks can be found at www.cisco.com/go/trademarks. Third party
trademarks mentioned are the property of their respective owners. The use of the word partner does not
imply a partnership relationship between Cisco and any other company. (1005R)
Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be
actual addresses and phone numbers. Any examples, command display output, network topology diagrams,
and other figures included in the document are shown for illustrative purposes only. Any use of actual IP
addresses or phone numbers in illustrative content is unintentional and coincidental.
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
191
X.25 Encapsulation on an ISDN BRI D-channel Interface Example
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
192
X.25 Throughput Negotiation
This feature enables a router to negotiate X.25 throughput parameters on behalf of end devices, thereby
making it possible for X.25 calls to reach devices that may not themselves be able to negotiate throughput.
History for the X.25 Throughput Negotiation Feature
Release
Modification
12.3(11)YN
This feature was introduced.
12.4(4)T
This feature was integrated into Cisco IOS
12.4(4)T.
Finding Support Information for Platforms and Cisco IOS Software Images
Use Cisco Feature Navigator to find information about platform support and Cisco IOS software image
support. Access Cisco Feature Navigator at http://www.cisco.com/go/fn . You must have an account on
Cisco.com. If you do not have an account or have forgotten your username or password, click Cancel
when presented with the login screen and then follow the instructions that subsequently appear.
•
•
•
•
•
•
Finding Feature Information, page 193
Restrictions for X.25 Throughput Negotiation, page 193
Information about X.25 Throughput Negotiation, page 194
How to Configure X.25 Throughput Negotiation, page 198
Configuration Examples for X.25 Throughput Negotiation, page 200
Additional References, page 201
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest feature
information and caveats, see the release notes for your platform and software release. To find information
about the features documented in this module, and to see a list of the releases in which each feature is
supported, see the Feature Information Table at the end of this document.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support.
To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Restrictions for X.25 Throughput Negotiation
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
193
X.25 Throughput Negotiation
Information about X.25 Throughput Negotiation
This feature currently supports only basic throughput classes; extended throughput classes are not
supported.
Information about X.25 Throughput Negotiation
In order for end devices in a network to support X.25 calls, they need to be able to negotiate X.25
throughput parameters. This feature enables a router to handle that negotiation on behalf of end devices that
cannot do it themselves.
Figure 23
Router Negotiating Throughput Between a Network and an End Device
The router does this by stripping out or inserting values, as appropriate for each case, in the "throughput
facility field" of the X.25 calls’ setup and confirmed messages (specifically, in the Call Request, Incoming
Call, Call Accepted, and Call Confirmed packets).
In order to insert values appropriately, the router interface connected to the end device must earlier have
been configured with the input and output bit rates that are intended to be used by the eventual X.25 call.
The rules according to which the router removes or inserts those bit rates are set by the x25 subscribe
throughput command, which can have three distinct states: no, basic or never. These forms of the
command work as follows when the router receives a call from the network and forwards that call onward
to the end device:
•
•
If the router has been configured by the command no x25 subscribe throughput, it will make no
change to the values it receives in the call’s facility field. The router merely forwards the message, and
those values, onward.
If the router has been configured by the 25 subscribe throughput basic form of this command, the
router will insert the bit rate values previously configured on its interface into the call’s facility field.
(The only exception is when those values are larger than the call’s values, in which case the router will
leave the call’s smaller values in place when it forwards the message.)
In cases when the router has substituted its own configured values for the values it detected in the incoming
call, the router also reports those new values in a Call Confirmed packet back out through the network to
the source device.
•
If the x25 subscribe throughput never form of the command has been entered, the router will remove
the values it receives in the call’s facility field. (And if the values previously configured on the router’s
interface are smaller than those contained in the call, the router will also replace the call’s values with
those smaller ones when it forwards the end device’s Call Confirmed packet back out to the network.)
How these behavior rules apply to each possible case is presented in the first table below.
When calls originate not in the network but in the end device, this command’s three states can have
somewhat different results, which are detailed in the second table below.
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X.25 Throughput Negotiation
Information about X.25 Throughput Negotiation
Table 14
Router Treatment of Throughput Facility Field in Incoming Call
Incoming call’s ‘Call
Request’ packet
Cisco IOS commands
applied
Results
Is interface configured How is Serial Line’s
Within ‘Incoming Call’
with throughput values? throughput subscription packet
configured?
Within ‘Call
Confirmed’ packet
Contains throughput
facility field
no x25 sub throughput
Facility field in message End device includes no
from network is sent to facility field in its Call
end device unmodified. Accepted packet to the
router. And the router
includes no facility field
in the Call Confirmed
packet it sends out to
the network.
x25 sub throughput
never
Router strips out facility Router sends values out
field, then forwards
to network only if the
message to end device. values configured on its
interface are smaller
than those received in
network call.
x25 sub throughput
basic
Router compares values Router sends that lower
in message with those
set out to the network.
configured on its
interface, and sends to
end device the lower
set.
no x25 sub throughput
No facility field sent to
end device.
No facility field sent out
to network.
x25 sub throughput
never
No facility field sent to
end device.
No facility field sent
back out to network.
x25 sub throughput
basic
Router inserts facility
field into message, and
forwards that to the end
device.
No facility field sent
back out to network.
no x25 sub throughput
Facility field sent to end End device includes no
device.
facility field in its Call
Accepted packet to the
router. And the router
includes no facility field
in the Call Confirmed
packet it sends out to
the network.
YES :
"x25 facility throughput
xxx yyy
Has no throughput
facility field
Contains throughput
facility field
NO :
"no x25 facility
throughput"
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
195
X.25 Throughput Negotiation
Information about X.25 Throughput Negotiation
Incoming call’s ‘Call
Request’ packet
Cisco IOS commands
applied
Has no throughput
facility field
Results
x25 sub throughput
never
Router strips out facility No facility field sent
field, then forwards
back out to network.
message to end device.
x25 sub throughput
basic
Facility field sent on to
end device.
No facility field sent
back out to network.
no x25 sub throughput
No facility field sent to
end device.
No facility field sent out
to network.
x25 sub throughput
never
No facility field sent to
end device.
No facility field sent
back out to network.
x25 sub throughput
basic
No facility field sent to
end device.
No facility field sent out
to network.
*Shaded rows (in PDF version) describe calls that contain no throughput facility field before they reach the
router.
Table 15
Router Treatment of Throughput Facility Field in Outgoing Call
Outgoing call’s ‘Call
Request’ packet
Cisco IOS commands
applied
Results
Is interface configured How is Serial Line’s
Within outgoing ‘Call
with throughput values? throughput subscription Request’ packet
configured?
Within received ‘Call
Confirmed’ packet
Contains throughput
facility field
Router forwards facility
field it receives in the
end device’s Call
Request packet out to
the network
unmodified.
YES :
"x25 facility throughput
xxx yyy
no x25 sub throughput
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
196
Router forwards facility
field it receives in the
Call Confirmed packet
from the network on to
the end device
unmodified.
X.25 Throughput Negotiation
Information about X.25 Throughput Negotiation
Outgoing call’s ‘Call
Request’ packet
Cisco IOS commands
applied
Has no throughput
facility field
Contains throughput
facility field
NO :
"no x25 facility
throughput"
Results
x25 sub throughput
never
Router refuses to
forward call on to the
network, and cancels it,
sending back to the end
device a Clear Request
packet with the Cause
Code field set to 3 (‘3’
stands for "Invalid
Facility Request").
Router also sends to the
end device a Diagnostic
Code field set to 65
(which stands for
"Facility Code Not
Allowed").
x25 sub throughput
basic
Router compares values
in message with those
configured on its
interface, and sends to
network the lower set.
Router sends that lower
set to the end device,
unless still different
values are received in
the Call Confirmed
message from the
network. In that case,
the router forwards that
network set to the end
device.
no x25 sub throughput
No facility field sent to
network.
No facility field sent to
end device.
x25 sub throughput
never
Router sends values
configured on its
interface out to the
network.
No facility field sent to
end device.
x25 sub throughput
basic
Router inserts facility
field into message, and
forwards that to the
network.
Router sends the
inserted facility field to
the end device.
no x25 sub throughput
Router forwards facility
field it receives in the
end device’s Call
Request packet out to
the network
unmodified.
Router forwards facility
field it receives in the
Call Confirmed packet
from the network on to
the end device
unmodified.
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
197
Configuring X.25 Throughput Negotiation
How to Configure X.25 Throughput Negotiation
Outgoing call’s ‘Call
Request’ packet
Cisco IOS commands
applied
Has no throughput
facility field
Results
x25 sub throughput
never
Router refuses to
forward call on to the
network, and cancels it,
sending back to the end
device a Clear Request
packet with the Cause
Code field set to 3 (‘3’
stands for "Invalid
Facility Request").
Router also sends to the
end device a Diagnostic
Code field set to 65
(which stands for
"Facility Code Not
Allowed").
x25 sub throughput
basic
Facility field sent on to
network.
Facility field sent back
to end device.
no x25 sub throughput
No facility field sent to
network.
No facility field sent to
end device.
x25 sub throughput
never
No facility field sent to
network.
No facility field sent to
end device.
x25 sub throughput
basic
No facility field sent to
network.
No facility field sent to
end device.
*Shaded rows (in PDF version) describe calls that contain no throughput facility field before they reach the
router.
How to Configure X.25 Throughput Negotiation
•
Configuring X.25 Throughput Negotiation, page 198
Configuring X.25 Throughput Negotiation
If you choose the basic keyword of the x25 subscribe throughput command below, you must first
configure the interface with the appropriate class negotiation values for input and output throughput across
the network by using the throughput in out keyword and arguments of the x25 facility command. For
more information about the x25 facilitycommand, see the Cisco IOS Wide-Area Networking Command
Reference.
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
198
X.25 Throughput Negotiation
How to Configure X.25 Throughput Negotiation
SUMMARY STEPS
1.
2.
3.
4.
5.
enable
configure terminal
interface interface-id
x25 subscribe throughput { never | basic }
exit
DETAILED STEPS
Command or Action
Purpose
Step 1 enable
Enables privileged EXEC mode.
•
Enter your password if prompted.
Example:
Router> enable
Step 2 configure terminal
Enters global configuration mode.
Example:
Router# configure terminal
Step 3 interface interface-id
Specifies the interface which is connected to the end device,
and enters interface configuration mode.
Example:
Router(config)# interface serial2/0
Step 4 x25 subscribe throughput { never | basic }
Enables the router to negotiate X.25 throughput for the end
device.
(In this example, the end device always expects the throughput
facility field to be present in incoming call setup packets).
Example:
Router(config-if)# x25 subscribe throughput
basic
Step 5 exit
Exits interface configuration mode.
Example:
Router(config-if)# exit
Examples
In this example, the end device never expects the throughput facility field to be present in incoming call
setup packets:
Router>
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
199
Basic example
Configuration Examples for X.25 Throughput Negotiation
enable
Router# configure terminal
Router(config)# interface serial2/0
Router(config-if)# x25 subscribe throughput never
Router(config-if)# exit
In this example, the end device always expects the throughput facility field to be present in incoming call
setup packets:
Router>
enable
Router# configure terminal
Router(config)# interface serial0/0
Router(config-if)# x25 subscribe throughput basic
Router(config-if)# exit
In this example, the active throughput negotiation capability on the just-illustrated interface (Serial 0/0)
gets turned off:
Router(config)# interface serial0/0
Router(config-if)# no x25 subscribe throughput
Router(config-if)# exit
Configuration Examples for X.25 Throughput Negotiation
•
•
Basic example, page 200
Never example, page 200
Basic example
In this example, the end device always expects the throughput facility field to be present in Incoming Call
packets. The router inserts its configured bit rate values--unless they are larger than the values in the
incoming call.
Router# configure terminal
Router(config)# interface serial2/0
Router(config-if)# x25 facility throughput 300 300
Router(config-if)# x25 subscribe throughput basic
Router(config-if)# end
Router#
Never example
In this example, the end device never expects the throughput facility field to be present in Incoming Call
packets. The router removes the facility field from incoming calls.
Router# configure terminal
Router(config)# interface serial2/0
Router(config-if)# x25 facility throughput 300 300
Router(config-if)# x25 subscribe throughput never
Router(config-if)# end
Router#
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
200
X.25 Throughput Negotiation
Additional References
Additional References
Related Documents
Related Topic
Document Title
Configuring X.25 throughput facilities
Cisco IOS Wide-Area Networking Command
Reference
Technical Assistance
Description
Link
The Cisco Technical Support website contains
http://www.cisco.com/techsupport
thousands of pages of searchable technical content,
including links to products, technologies, solutions,
technical tips, and tools. Registered Cisco.com
users can log in from this page to access even more
content.
Cisco and the Cisco Logo are trademarks of Cisco Systems, Inc. and/or its affiliates in the U.S. and other
countries. A listing of Cisco's trademarks can be found at www.cisco.com/go/trademarks. Third party
trademarks mentioned are the property of their respective owners. The use of the word partner does not
imply a partnership relationship between Cisco and any other company. (1005R)
Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be
actual addresses and phone numbers. Any examples, command display output, network topology diagrams,
and other figures included in the document are shown for illustrative purposes only. Any use of actual IP
addresses or phone numbers in illustrative content is unintentional and coincidental.
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
201
Never example
Wide-Area Networking Configuration Guide: SMDS and X.25 and LAPB Cisco IOS Release 12.4T
202
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