IP Overlapping Address Pools
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IP Overlapping Address Pools

Table Of Contents

IP Overlapping Address Pools

Finding Feature Information

Contents

Restrictions for IP Overlapping Address Pools

Information About IP Overlapping Address Pools

Benefits

How IP Address Groups Work

How to Configure IP Overlapping Address Pools

Configuring and Verifying a Local Pool Group

Configuration Examples for Configuring IP Overlapping Address Pools

Define Local Address Pooling as the Global Default Mechanism Example

Configure Multiple Ranges of IP Addresses into One Pool Example

Additional References

Related Documents

Standards

MIBs

RFCs

Technical Assistance

Feature Information for Configuring IP Overlapping Address Pools

Glossary


IP Overlapping Address Pools


First Published: May 2, 2005
Last Updated: May 4, 2009

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.

Finding Feature Information

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 for Configuring IP Overlapping Address Pools" section.

Use Cisco Feature Navigator to find information about platform support and Cisco IOS XE software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

Contents

Restrictions for IP Overlapping Address Pools

Information About IP Overlapping Address Pools

How to Configure IP Overlapping Address Pools

Configuration Examples for Configuring IP Overlapping Address Pools

Additional References

Glossary

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.

Information About IP Overlapping Address Pools

To configure the IP Overlapping Address Pools feature, you should understand the following concepts:

Benefits

How IP Address Groups Work

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

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

This section contains the following procedure:

Configuring and Verifying a Local Pool Group

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]]

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

Enter your password if prompted.

Step 2 

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3 

ip local pool {default | poolname} {low-ip-address [high-ip-address] [group group-name] [cache-size size]}

Example:

Router(config)# ip local pool testpool 10.2.2.1 10.2.2.10 group testgroup cache-size 10000

Configures a group of local IP address pools, gives this group a name, and specifies a cache size.

Step 4 

show ip local pool [poolname | [group group-name]]

Example:

Router(config)# show ip local pool group testgroup testpool

Displays statistics for any defined IP address pools.

Configuration Examples for Configuring IP Overlapping Address Pools

This section provides the following configuration examples:

Define Local Address Pooling as the Global Default Mechanism Example

Configure Multiple Ranges of IP Addresses into One Pool Example

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

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

RFCs
Title

RFC 826

Address Resolution Protocol

RFC 903

Reverse Address Resolution Protocol

RFC 1027

Proxy Address Resolution Protocol

RFC 1042

Standard for the Transmission of IP Datagrams over IEEE 802 Networks


Technical Assistance

Description
Link

The Cisco Support website provides extensive online resources, including documentation and tools 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 services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds.

Access to most tools on the Cisco Support website requires a Cisco.com user ID and password.

http://www.cisco.com/techsupport


Feature Information for Configuring IP Overlapping Address Pools

Table 1 lists the features in this module and provides links to specific configuration information.

Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which Cisco IOS XE software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.


Note Table 1 lists only the Cisco IOS XE software release that introduced support for a given feature in a given Cisco IOS XE software release train. Unless noted otherwise, subsequent releases of that Cisco IOS XE software release train also support that feature.


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 pool and 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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