IP Overlapping Address Pools

IP Overlapping Address Pools
Last Updated: December 12, 2011
The IP Overlapping Address Pools feature improves flexibility in assigning IP addresses dynamically. This
feature allows you to configure overlapping IP address pool groups to create different address spaces and
concurrently use the same IP addresses in different address spaces.
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Finding Feature Information, page 1
Restrictions for IP Overlapping Address Pools, page 1
Information About IP Overlapping Address Pools, page 2
How to Configure IP Overlapping Address Pools, page 2
Configuration Examples for Configuring IP Overlapping Address Pools, page 3
Additional References, page 4
Feature Information for Configuring IP Overlapping Address Pools, page 5
Glossary, page 6
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 IP Overlapping Address Pools
The Cisco IOS XE software checks for duplicate addresses on a per-group basis. The check for duplicate
addresses means that you can configure pools in multiple groups that could have possible duplicate
addresses. The IP Overlapping Address Pools feature should be used only in cases where overlapping IP
address pools make sense, such as Multiprotocol Label Switching (MPLS) Virtual Private Network (VPN)
environments where multiple IP address spaces are supported.
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Benefits
Information About IP Overlapping Address Pools
Information About IP Overlapping Address Pools
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Benefits, page 2
How IP Address Groups Work, page 2
Benefits
The IP Overlapping Address Pools gives greater flexibility in assigning IP addresses dynamically. It allows
you to configure overlapping IP address pool groups to create different address spaces and concurrently use
the same IP addresses in different address spaces.
How IP Address Groups Work
IP Control Protocol (IPCP) IP pool processing implements all IP addresses as belonging to a single IP
address space, and a given IP address should not be assigned multiple times. IP developments such as
virtual private dialup network (VPDN) and Network Address Translation (NAT) implement the concept of
multiple IP address spaces where it can be meaningful to reuse IP addresses, although such usage must
ensure that these duplicate address are not placed in the same IP address space. An IP address group to
support multiple IP address spaces and still allow the verification of nonoverlapping IP address pools
within a pool group. Pool names must be unique within the router. The pool name carries an implicit group
identifier because that pool name can be associated only with one group. Pools without an explicit group
name are considered members of the base system group and are processed in the same manner as the
original IP pool implementation.
Existing configurations are not affected by the new pool feature. The “group” concept is an extension of the
existing ip local pool command. Processing of pools that are not specified as a member of a group is
unchanged from the existing implementation.
How to Configure IP Overlapping Address Pools
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Configuring and Verifying a Local Pool Group, page 2
Configuring and Verifying a Local Pool Group
Perform this task to configure a local pool group and verify that it exists.
SUMMARY STEPS
1. enable
2. configure terminal
3. ip local pool {default | poolname} {low-ip-address [high-ip-address] [group group-name] [cache-size
size]}
4. show ip local pool [poolname | [group group-name]]
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Define Local Address Pooling as the Global Default Mechanism Example
Configuration Examples for Configuring IP Overlapping Address Pools
DETAILED STEPS
Command or Action
Purpose
Step 1 enable
Enables privileged EXEC mode.
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Enter your password if prompted.
Example:
Router> enable
Step 2 configure terminal
Enters global configuration mode.
Example:
Router# configure terminal
Step 3 ip local pool {default | poolname} {low-ip-address [high-ip-address]
[group group-name] [cache-size size]}
Configures a group of local IP address pools,
gives this group a name, and specifies a cache
size.
Example:
Router(config)# ip local pool testpool 10.2.2.1 10.2.2.10
group testgroup cache-size 10000
Step 4 show ip local pool [poolname | [group group-name]]
Displays statistics for any defined IP address
pools.
Example:
Router(config)# show ip local pool group testgroup testpool
Configuration Examples for Configuring IP Overlapping
Address Pools
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Define Local Address Pooling as the Global Default Mechanism Example, page 3
Configure Multiple Ranges of IP Addresses into One Pool Example, page 4
Define Local Address Pooling as the Global Default Mechanism Example
The following example shows how to configure local pooling as the global default mechanism:
ip address-pool local
ip local pool default 192.168.15.15 192.168.15.16
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Configure Multiple Ranges of IP Addresses into One Pool Example
Additional References
Configure Multiple Ranges of IP Addresses into One Pool Example
The following example shows how to configure two ranges of IP addresses for one IP address pool:
ip local pool default 192.169.10.10 192.169.10.20
ip local pool default 192.168.50.25 192.168.50.50
Additional References
The following sections provide references related to configuring IP Overlapping Address Pools.
Related Documents
Related Topic
Document Title
Dial commands: complete command syntax,
command mode, command history, defaults, usage
guidelines, and examples
Cisco IOS Dial Services Command Reference
IP address pooling
“Configuring Media-Independent PPP and
Multilink PPP” chapter of the Cisco IOS XE Dial
Technologies Configuration Guide
Standards
Standards
Title
No new or modified standards are supported by this -feature, and support for existing standards has not
been modified by this feature.
MIBs
MIBs
MIBs Link
No new or modified MIBs are supported by this
feature, and support for existing MIBs has not been
modified by this feature.
To locate and download MIBs for selected
platforms, Cisco IOS XE releases, and feature sets,
use Cisco MIB Locator found at the following
URL:
http://www.cisco.com/go/mibs
RFCs
4
RFCs
Title
RFC 826
Address Resolution Protocol
RFC 903
Reverse Address Resolution Protocol
Configure Multiple Ranges of IP Addresses into One Pool Example
Feature Information for Configuring IP Overlapping Address Pools
RFCs
Title
RFC 1027
Proxy Address Resolution Protocol
RFC 1042
Standard for the Transmission of IP Datagrams
over IEEE 802 Networks
Technical Assistance
Description
Link
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http://www.cisco.com/techsupport
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for troubleshooting and resolving technical issues
with Cisco products and technologies.
To receive security and technical information about
your products, you can subscribe to various
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from Field Notices), the Cisco Technical Services
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Feeds.
Access to most tools on the Cisco Support website
requires a Cisco.com user ID and password.
Feature Information for Configuring IP Overlapping Address
Pools
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.
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Configure Multiple Ranges of IP Addresses into One Pool Example
Glossary
Table 1
Feature Information for Configuring IP Overlapping Address Pools
Feature Name
Releases
Feature Information
IP Overlapping Address Pools
Cisco IOS XE Release 2.1
The IP Overlapping Address
Pools feature improves flexibility
in assigning IP addresses
dynamically. This feature allows
you to configure overlapping IP
address pool groups to create
different address spaces and
concurrently use the same IP
addresses in different address
spaces.
The following commands were
modified by this feature:ip local
pooland show ip local pool.
Glossary
IPCP --IP Control Protocol. Protocol that establishes and configures IP over PPP.
MPLS --Multiprotocol Label Switching. Switching method that forwards IP traffic using a label. This label
instructs the routers and the switches in the network where to forward the packets based on preestablished
IP routing information.
NAT --Network Address Translation. Mechanism for reducing the need for globally unique IP addresses.
NAT allows an organization with addresses that are not globally unique to connect to the Internet by
translating those addresses into globally routable address space. Also known as Network Address
Translator.
VPDN --virtual private dialup network. Also known as virtual private dial network. A VPDN is a network
that extends remote access to a private network using a shared infrastructure. VPDNs use Layer 2 tunnel
technologies (L2F, L2TP, and PPTP) to extend the Layer 2 and higher parts of the network connection
from a remote user across an ISP network to a private network. VPDNs are a cost-effective method of
establishing a long distance, point-to-point connection between remote dial users and a private network.
See also VPN.
VPN --Virtual Private Network. Enables IP traffic to travel securely over a public TCP/IP network by
encrypting all traffic from one network to another. A VPN uses “tunneling” to encrypt all information at
the IP level.
VRF --A VPN routing and forwarding instance. A VRF consists of an IP routing table, a derived
forwarding table, a set of interfaces that use the forwarding table, and a set of rules and routing protocols
that determine what goes into the forwarding table. In general, a VRF includes the routing information that
defines a customer VPN site that is attached to a PE router.
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and other countries. To view a list of Cisco trademarks, go to this URL: www.cisco.com/go/trademarks.
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Configure Multiple Ranges of IP Addresses into One Pool Example
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. (1110R)
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.
© 2011 Cisco Systems, Inc. All rights reserved.
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