PPP IP Unique Address and Prefix Detection

First Published: November 24, 2010
Last Updated: November 24, 2010

The PPP IP Unique Address and Prefix Detection feature checks the uniqueness of IPv4 address and IPv6 prefix on the Broadband Remote Access Server (BRAS). PPP disconnects the session if it detects a duplicate IPv4 address and IPv6 prefix.

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 for PPP IP Unique Address and Prefix Detection" section.

Use Cisco Feature Navigator to find information about platform support and Cisco 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

•"Information About PPP IP Unique Address and Prefix Detection" section

•"How to Configure PPP IP Unique Address and Prefix Detection" section

•"Configuration Examples for PPP IP Unique Address and Prefix Detection" section

•"Additional References" section

•"Feature Information for PPP IP Unique Address and Prefix Detection" section

Information About PPP IP Unique Address and Prefix Detection

•IPv6 checks if the prefix is unique when it is installed on an interface. If the prefix installation fails, PPP disconnects the session.

•PPP also checks if the IPv4 address is unique. PPP disconnects the session if a duplicate IPv4 address is detected.

How to Configure PPP IP Unique Address and Prefix Detection

Perform this task to configure the PPP IP Unique Address and Prefix Detection feature.

SUMMARY STEPS

1. enable

2. configure terminal

3. interface virtual-template interface-number

4. ppp ipcp address required

5. ppp ipcp address unique

6. ppp ipv6cp address unique

7. ppp timeout ncp seconds

8. exit

9. ppp ncp override local

10. end

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 

interface virtual-template interface-number

Example:

Router(config)# interface virtual-template 7

Selects the Virtual Template interface and enters interface configuration mode.

Step 4 

ppp ipcp address required

Example:

Router(config-if)# ppp ipcp address required

PPP disconnects the peer if no IP address is negotiated.

Step 5 

ppp ipcp address unique

Example:

Router(config-if)# ppp ipcp address unique

PPP disconnects the peer if the IP address is already in use.

Step 6 

ppp ipv6cp address unique

Example:

Router(config-if)# ppp ipv6cp address unique

PPP disconnects the peer if the IPv6 prefix is already in use.

Step 7 

ppp timeout ncp seconds

Example:

Router(config-if)# ppp timeout ncp 30

PPP sets the maximum time in seconds to wait for the network layer to negotiate.

Step 8 

exit

Example:

Router(config-if)# exit

Exits interface configuration mode and returns to global configuration mode.

Step 9 

ppp ncp override local

Example:

Router(config)# ppp ncp override local

PPP overrides the local dual-stack configuration, checks the permitted Network Control Programs (NCP), and rejects user-initiated NCP negotiation.

Step 10 

end

Example:

Router(config)# end

Exits global configuration mode and returns to privileged EXEC mode.

Configuration Examples for PPP IP Unique Address and Prefix Detection

This section provides the following configuration example:

•Example: PPP Unique Address and Prefix Detection

Example: PPP Unique Address and Prefix Detection

To enable the PPP IP Unique Address nd Prefix Detection feature, use the following configuration. 

Router# configure terminal

Router(config)# interface virtual-template 7 

Router(config-if)# ppp ipcp address required 

Router(config-if)# ppp ipcp address unique 

Router(config-if)# ppp ipv6cp address unique 

Router(config-if)# ppp timeout ncp 30

Router(config-if)# exit

Router(config)# ppp ncp override local

Router(config)# end

Additional References

Related Documents

Related Topic
Document Title

Cisco IOS commands

Cisco IOS Master Commands List, All Releases

Broadband Access Aggregation and DSL commands

Cisco IOS Broadband Access Aggregation and DSL
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 PPP IP Unique Address and Prefix Detection

Table 1 lists the release history for this feature.

Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which 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 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.

Table 1 Feature Information for PPP IP Unique Address and Prefix Detection 

Feature Name
Releases
Feature Information

PPP IP Unique Address and Prefix Detection

Cisco IOS XE
Release 3.2S

The PPP IP Unique Address and Prefix Detection feature checks the uniqueness of IPv4 address and IPv6 prefix on the BRAS. PPP disconnects the session if it detects a duplicate IPv4 address and IPv6 prefix.

The following commands were introduced: ppp ipv6cp address unique, ppp ncp override local.


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