Broadband Access Aggregation and DSL Configuration Guide, Cisco IOS XE Release 3S
PPP IP Unique Address and Prefix Detection
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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 at the end of this module.

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 ActionPurpose
    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.