Chapter 1 Basic Router Configuration

C H A P T E R
1
Basic Router Configuration
This chapter provides procedures for configuring the basic parameters of your Cisco router, including
global parameter settings, routing protocols, interfaces, and command-line access. It also describes the
default configuration on startup.
Note
Individual router models may not support every feature described throughout this guide. Features not
supported by a particular router are indicated whenever possible.
This chapter contains the following sections:
•
Interface Port Labels
•
Viewing the Default Configuration
•
Information Needed for Configuration
•
Configuring Basic Parameters
•
Configuring Static Routes
•
Configuring Dynamic Routes
•
Configuring Enhanced IGRP
Each section includes a configuration example and verification steps, as available.
For complete information on how to access global configuration mode, see the “Entering Global
Configuration Mode” section in Appendix A, “Cisco IOS Basic Skills.” For more information on the
commands used in the following tables, see the Cisco IOS Release 12.3 documentation set.
Interface Port Labels
Table 1-1 lists the interfaces supported for each router and their associated port labels on the equipment.
Table 1-1
Supported Interfaces and Associated Port Labels by Cisco Router
Router
Interface
Port Label
Cisco 851
Fast Ethernet LAN
LAN (top), FE0–FE3 (bottom)
Fast Ethernet WAN
WAN (top), FE4 (bottom)
Wireless LAN
(no label)
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Viewing the Default Configuration
Table 1-1
Supported Interfaces and Associated Port Labels by Cisco Router (continued)
Router
Interface
Port Label
Cisco 871
Fast Ethernet LAN
FE0–FE3
Fast Ethernet WAN
FE4
Wireless LAN
LEFT, RIGHT/PRIMARY
USB
1–0
Fast Ethernet LAN
LAN (top), FE0–FE3 (bottom)
ATM WAN
ADSLoPOTS
Wireless LAN
(no label)
Fast Ethernet LAN
LAN (top), FE0–FE3 (bottom)
ATM WAN
ADSLoISDN
Wireless LAN
LEFT, RIGHT/PRIMARY
BRI
ISDN S/T
Fast Ethernet LAN
LAN (top), FE0–FE3 (bottom)
ATM WAN
ADSLoPOTS
Wireless LAN
LEFT, RIGHT/PRIMARY
Fast Ethernet LAN
FE0–FE3
ATM WAN
G.SHDSL
Wireless LAN
LEFT, RIGHT/PRIMARY
BRI
ISDN S/T
Cisco 857
Cisco 876
Cisco 877
Cisco 878
Viewing the Default Configuration
When you first boot up your Cisco router, some basic configuration has already been performed. All of
the LAN and WAN interfaces have been created, console and VTY ports are configured, and the inside
interface for Network Address Translation has been assigned. Use the show running-config command
to view the initial configuration, as shown in Example 1-1.
Example 1-1
Cisco 851 Default Configuration on Startup
Router# show running-config
Building configuration...
Current configuration : 1090 bytes
!
version 12.3
no service pad
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname Router
!
boot-start-marker
boot-end-marker
!
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Viewing the Default Configuration
no aaa new-model
ip subnet-zero
!
ip cef
ip ips po max-events 100
no ftp-server write-enable
!
interface FastEthernet0
no ip address
shutdown
!
interface FastEthernet1
no ip address
shutdown
!
interface FastEthernet2
no ip address
shutdown
!
interface FastEthernet3
no ip address
shutdown
!
interface FastEthernet4
no ip address
duplex auto
speed auto
!
interface Dot11Radio0
no ip address
shutdown
speed basic-1.0 basic-2.0 basic-5.5 6.0 9.0 basic-11.0 12.0 18.0 24.0 36.0 48.0
54.0
rts threshold 2312
station-role root
!
interface Vlan1
no ip address
!
ip classless
!
no ip http server
no ip http secure-server
!
control-plane
!
line con 0
no modem enable
transport preferred all
transport output all
line aux 0
transport preferred all
transport output all
line vty 0 4
login
transport preferred all
transport input all
transport output all
!
end
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Information Needed for Configuration
Information Needed for Configuration
You need to gather some or all of the following information, depending on your planned network
scenario, prior to configuring your network
•
If you are setting up an Internet connection, gather the following information:
– Point-to-Point Protocol (PPP) client name that is assigned as your login name
– PPP authentication type: Challenge Handshake Authentication Protocol (CHAP) or Password
Authentication Protocol (PAP)
– PPP password to access your Internet service provider (ISP) account
– DNS server IP address and default gateways
•
If you are setting up a connection to a corporate network, you and the network administrator must
generate and share the following information for the WAN interfaces of the routers:
– PPP authentication type: CHAP or PAP
– PPP client name to access the router
– PPP password to access the router
•
If you are setting up IP routing:
– Generate the addressing scheme for your IP network.
– Determine the IP routing parameter information, including IP address, and ATM permanent
virtual circuits (PVCs). These PVC parameters are typically virtual path identifier (VPI), virtual
circuit identifier (VCI), and traffic shaping parameters.
– Determine the number of PVCs that your service provider has given you, along with their VPIs
and VCIs.
– For each PVC determine the type of AAL5 encapsulation supported. It can be one of the
following:
AAL5SNAP—This can be either routed RFC 1483 or bridged RFC 1483. For routed RFC 1483,
the service provider must provide you with a static IP address. For bridged RFC 1483, you may
use DHCP to obtain your IP address, or you may obtain a static IP address from your service
provider.
AAL5MUX PPP—With this type of encapsulation, you need to determine the PPP-related
configuration items.
•
If you plan to connect over an ADSL or G.SHDSL line:
– Order the appropriate line from your public telephone service provider.
For ADSL lines—Ensure that the ADSL signaling type is DMT (also called ANSI T1.413) or
DMT Issue 2.
For G.SHDSL lines—Verify that the G.SHDSL line conforms to the ITU G.991.2 standard and
supports Annex A (North America) or Annex B (Europe).
Once you have collected the appropriate information, you can perform a full configuration on
your router, beginning with the tasks in the “Configuring Basic Parameters” section.
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Configuring Basic Parameters
Configuring Basic Parameters
To configure the router, perform one or more of these tasks:
•
Configure Global Parameters
•
Configure Fast Ethernet LAN Interfaces
•
Configure WAN Interfaces
•
Configuring a Loopback Interface
•
Configuring Command-Line Access to the Router
A configuration example is presented with each task to show the network configuration following
completion of that task.
Configure Global Parameters
Perform these steps to configure selected global parameters for your router:
Step 1
Command
Purpose
configure terminal
Enters global configuration mode, when using the
console port.
Example:
If you are connecting to the router using a remote
terminal, use the following:
Router> enable
Router# configure terminal
Router(config)#
Step 2
hostname name
telnet router name or address
Login: login id
Password: *********
Router> enable
Specifies the name for the router.
Example:
Router(config)# hostname Router
Router(config)#
Step 3
enable secret password
Specifies an encrypted password to prevent
unauthorized access to the router.
Example:
Router(config)# enable secret cr1ny5ho
Router(config)#
Step 4
no ip domain-lookup
Disables the router from translating unfamiliar
words (typos) into IP addresses.
Example:
Router(config)# no ip domain-lookup
Router(config)#
For complete information on the global parameter commands, see the Cisco IOS Release 12.3
documentation set.
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Configuring Basic Parameters
Configure Fast Ethernet LAN Interfaces
The Fast Ethernet LAN interfaces on your router are automatically configured as part of the default
VLAN and as such, they are not configured with individual addresses. Access is afforded through the
VLAN. You may assign the interfaces to other VLANs if desired. For more information about creating
VLANs, see Chapter 5, “Configuring a LAN with DHCP and VLANs.”
Configure WAN Interfaces
The Cisco 851 and Cisco 871 routers each have one Fast Ethernet interface for WAN connection. The
Cisco 857, Cisco 877, and Cisco 878 routers each have one ATM interface for WAN connection.
Based on the router model you have, configure the WAN interface(s) using one of the following
procedures:
•
Configure the Fast Ethernet WAN Interface
•
Configure the ATM WAN Interface
Configure the Fast Ethernet WAN Interface
This procedure applies only to the Cisco 851 and Cisco 871 router models. Perform these steps to
configure the Fast Ethernet interface, beginning in global configuration mode:
Step 1
Command
Purpose
interface type number
Enters the configuration mode for a Fast
Ethernet WAN interface on the router.
Example:
Router(config)# interface fastethernet 4
Router(config-int)#
Step 2
ip address ip-address mask
Sets the IP address and subnet mask for the
specified Fast Ethernet interface.
Example:
Router(config-int)# ip address 192.168.12.2
255.255.255.0
Router(config-int)#
Step 3
no shutdown
Example:
Enables the Ethernet interface, changing its
state from administratively down to
administratively up.
Router(config-int)# no shutdown
Router(config-int)#
Step 4
exit
Example:
Exits configuration mode for the Fast Ethernet
interface and returns to global configuration
mode.
Router(config-int)# exit
Router(config)#
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Configuring Basic Parameters
Configure the ATM WAN Interface
This procedure applies only to the Cisco 857, Cisco 876, Cisco 877 and Cisco 878 models.
Perform these steps to configure the ATM interface, beginning in global configuration mode:
Step 1
Command
Purpose
For the Cisco 878 model only:
For routers using the G.SHDSL signaling, perform
these commands. Ignore this step for routers using
ADSL signaling.
controller dsl 0
mode atm
exit
Example:
Router(config)# controller dsl 0
Router(config-controller)# mode atm
Router(config-controller)# exit
Router(config)#
Step 2
interface type number
Identifies and enters the configuration mode for an
ATM interface.
Example:
Router(config)# interface atm0
Router(config-int)#
Step 3
ip address ip-address mask
Sets the IP address and subnet mask for the ATM
interface.
Example:
Router(config-int)# ip address 10.10.10.100
255.255.255.0
Router(config-int)#
Step 4
no shutdown
Enables the ATM 0 interface.
Example:
Router(config-int)# no shutdown
Router(config-int)#
Step 5
exit
Exits configuration mode for the ATM interface
and returns to global configuration mode.
Example:
Router(config-int)# exit
Router(config)#
Configure the Wireless Interface
The wireless interface enables connection to the router through a wireless LAN connection. For more
information about configuring a wireless connection, see Chapter 9, “Configuring a Wireless LAN
Connection,” and the Cisco Access Router Wireless Configuration Guide.
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Configuring Basic Parameters
Configuring a Loopback Interface
The loopback interface acts as a placeholder for the static IP address and provides default routing
information.
For complete information on the loopback commands, see the Cisco IOS Release 12.3
documentation set.
Perform these steps to configure a loopback interface:
Step 1
Command
Purpose
interface type number
Enters configuration mode for the loopback
interface.
Example:
Router(config)# interface Loopback 0
Router(config-int)#
Step 2
ip address ip-address mask
Sets the IP address and subnet mask for the
loopback interface.
Example:
Router(config-int)# ip address 10.108.1.1
255.255.255.0
Router(config-int)#
Step 3
exit
Example:
Exits configuration mode for the loopback
interface and returns to global configuration
mode.
Router(config-int)# exit
Router(config)#
Configuration Example
The loopback interface in this sample configuration is used to support Network Address Translation
(NAT) on the virtual-template interface. This configuration example shows the loopback interface
configured on the Fast Ethernet interface with an IP address of 10.10.10.100/24, which acts as a static
IP address. The loopback interface points back to virtual-template1, which has a negotiated IP address.
!
interface loopback 0
ip address 10.10.10.100 255.255.255.0 (static IP address)
ip nat outside
!
interface Virtual-Template1
ip unnumbered loopback0
no ip directed-broadcast
ip nat outside
!
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Configuring Basic Parameters
Verifying Your Configuration
To verify that you have properly configured the loopback interface, enter the show interface loopback
command. You should see verification output similar to the following example.
Router# show interface loopback 0
Loopback0 is up, line protocol is up
Hardware is Loopback
Internet address is 10.10.10.100/24
MTU 1514 bytes, BW 8000000 Kbit, DLY 5000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation LOOPBACK, loopback not set
Last input never, output never, output hang never
Last clearing of "show interface" counters never
Queueing strategy: fifo
Output queue 0/0, 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
0 packets input, 0 bytes, 0 no buffer
Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
0 packets output, 0 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 output buffer failures, 0 output buffers swapped out
Another way to verify the loopback interface is to ping it:
Router# ping 10.10.10.100
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.10.10.100, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/4 ms
Configuring Command-Line Access to the Router
Perform these steps to configure parameters to control access to the router, beginning in global
configuration mode.
Step 1
Command
Purpose
line [aux | console | tty | vty] line-number
Enters line configuration mode, and specifies the
type of line.
Example:
This example specifies a console terminal for
access.
Router(config)# line console 0
Router(config)#
Step 2
password password
Specifies a unique password for the console
terminal line.
Example:
Router(config)# password 5dr4Hepw3
Router(config)#
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Configuring Basic Parameters
Step 3
Command
Purpose
login
Enables password checking at terminal session
login.
Example:
Router(config)# login
Router(config)#
Step 4
exec-timeout minutes [seconds]
Example:
Router(config)# exec-timeout 5 30
Router(config)#
Step 5
line [aux | console | tty | vty] line-number
Sets the interval that the EXEC command
interpreter waits until user input is detected. The
default is 10 minutes. Optionally, add seconds to
the interval value.
This example shows a timeout of 5 minutes and
30 seconds. Entering a timeout of 0 0 specifies
never to time out.
Specifies a virtual terminal for remote console
access.
Example:
Router(config)# line vty 0 4
Router(config)#
Step 6
password password
Specifies a unique password for the virtual
terminal line.
Example:
Router(config)# password aldf2ad1
Router(config)#
Step 7
login
Enables password checking at the virtual terminal
session login.
Example:
Router(config)# login
Router(config)#
Step 8
end
Exits line configuration mode, and returns to
privileged EXEC mode.
Example:
Router(config)# end
Router#
For complete information about the command line commands, see the Cisco IOS Release 12.3
documentation set.
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Configuring Static Routes
Configuration Example
The following configuration shows the command-line access commands.
You do not need to input the commands marked “default.” These commands appear automatically in the
configuration file generated when you use the show running-config command.
!
line con 0
exec-timeout 10 0
password 4youreyesonly
login
transport input none (default)
stopbits 1 (default)
line vty 0 4
password secret
login
!
Configuring Static Routes
Static routes provide fixed routing paths through the network. They are manually configured on the
router. If the network topology changes, the static route must be updated with a new route. Static routes
are private routes unless they are redistributed by a routing protocol. Configuring static routes on the
Cisco 850 and Cisco 870 series routers is optional.
Perform these steps to configure static routes, beginning in global configuration mode:
Step 1
Command
Purpose
ip route prefix mask {ip-address | interface-type
interface-number [ip-address]}
Specifies the static route for the IP packets.
Example:
Router(config)# ip route 192.168.1.0
255.255.0.0 10.10.10.2
Router(config)#
Step 2
end
For details about this command and additional
parameters that can be set, see the Cisco IOS IP
Command Reference, Volume 2 of 4: Routing
Protocols.
Exits router configuration mode, and enters
privileged EXEC mode.
Example:
Router(config)# end
Router#
For complete information on the static routing commands, see the Cisco IOS Release 12.3
documentation set. For more general information on static routing, see Appendix B, “Concepts.”
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Configuring Dynamic Routes
Configuration Example
In the following configuration example, the static route sends out all IP packets with a destination IP
address of 192.168.1.0 and a subnet mask of 255.255.255.0 on the Fast Ethernet interface to another
device with an IP address of 10.10.10.2. Specifically, the packets are sent to the configured PVC.
You do not need to enter the commands marked “(default).” These commands appear automatically in
the configuration file generated when you use the show running-config command.
!
ip classless (default)
ip route 192.168.1.0 255.255.255.0 10.10.10.2!
Verifying Your Configuration
To verify that you have properly configured static routing, enter the show ip route command and look
for static routes signified by the “S.”
You should see verification output similar to the following example.
Router# show ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route
Gateway of last resort is not set
10.0.0.0/24 is subnetted, 1 subnets
C
10.108.1.0 is directly connected, Loopback0
S* 0.0.0.0/0 is directly connected, FastEthernet0
Configuring Dynamic Routes
In dynamic routing, the network protocol adjusts the path automatically, based on network traffic or
topology. Changes in dynamic routes are shared with other routers in the network.
The Cisco routers can use IP routing protocols, such as Routing Information Protocol (RIP) or Enhanced
Interior Gateway Routing Protocol (EIGRP), to learn routes dynamically. You can configure either of
these routing protocols on your router.
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Configuring Dynamic Routes
Configuring RIP
Perform these steps to configure the RIP routing protocol on the router, beginning in global
configuration mode:
Step 1
Command
Task
router rip
Enters router configuration mode, and enables RIP
on the router.
Example:
Router> configure terminal
Router(config)# router rip
Router(config-router)#
Step 2
version {1 | 2}
Specifies use of RIP version 1 or 2.
Example:
Router(config-router)# version 2
Router(config-router)#
Step 3
network ip-address
Specifies a list of networks on which RIP is to be
applied, using the address of the network of
directly connected networks.
Example:
Router(config-router)# network 192.168.1.1
Router(config-router)# network 10.10.7.1
Router(config-router)#
Step 4
no auto-summary
Example:
Router(config-router)# no auto-summary
Router(config-router)#
Step 5
end
Disables automatic summarization of subnet routes
into network-level routes. This allows subprefix
routing information to pass across classful network
boundaries.
Exits router configuration mode, and enters
privileged EXEC mode.
Example:
Router(config-router)# end
Router#
For complete information on the dynamic routing commands, see the Cisco IOS Release 12.3
documentation set. For more general information on RIP, see Appendix B, “Concepts.”
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Configuring Enhanced IGRP
Configuration Example
The following configuration example shows RIP version 2 enabled in IP network 10.0.0.0 and
192.168.1.0.
Execute the show running-config command from privileged EXEC mode to see this configuration.
!
router rip
version 2
network 10.0.0.0
network 192.168.1.0
no auto-summary
!
Verifying Your Configuration
To verify that you have properly configured RIP, enter the show ip route command and look for RIP
routes signified by “R.” You should see a verification output like the example shown below.
Router# show ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route
Gateway of last resort is not set
C
R
10.0.0.0/24 is subnetted, 1 subnets
10.108.1.0 is directly connected, Loopback0
3.0.0.0/8 [120/1] via 2.2.2.1, 00:00:02, Ethernet0/0
Configuring Enhanced IGRP
Perform these steps to configure Enhanced IGRP (EIGRP), beginning in global configuration mode:
Step 1
Command
Purpose
router eigrp as-number
Enters router configuration mode, and enables
EIGRP on the router. The autonomous-system
number identifies the route to other EIGRP routers
and is used to tag the EIGRP information.
Example:
Router(config)# router eigrp 109
Router(config)#
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Step 2
Command
Purpose
network ip-address
Specifies a list of networks on which EIGRP is to
be applied, using the IP address of the network of
directly connected networks.
Example:
Router(config)# network 192.145.1.0
Router(config)# network 10.10.12.115
Router(config)#
Step 3
end
Exits router configuration mode, and enters
privileged EXEC mode.
Example:
Router(config-router)# end
Router#
For complete information on the IP EIGRP commands, see the Cisco IOS Release 12.3 documentation
set. For more general information on EIGRP concepts, see Appendix B, “Concepts.”
Configuration Example
The following configuration example shows the EIGRP routing protocol enabled in IP networks
192.145.1.0 and 10.10.12.115. The EIGRP autonomous system number is 109.
Execute the show running-config command from privileged EXEC mode to see this configuration.
!
router eigrp 109
network 192.145.1.0
network 10.10.12.115
!
Verifying Your Configuration
To verify that you have properly configured IP EIGRP, enter the show ip route command, and look for
EIGRP routes indicated by “D.” You should see verification output similar to the following example.
Router# show ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route
Gateway of last resort is not set
C
D
10.0.0.0/24 is subnetted, 1 subnets
10.108.1.0 is directly connected, Loopback0
3.0.0.0/8 [90/409600] via 2.2.2.1, 00:00:02, Ethernet0/0
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