PPP IP Unique Address and Prefix Detection

The PPP IP Unique Address and Prefix Detection feature checks the uniqueness of IPv4 addresses and IPv6 prefixes 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 caveats and feature information, see Bug Search Tool and 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.

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 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

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

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.
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 .