PPP for IPv6

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 for IPv6

Accounting Start and Stop Messages

PPP calls a registry to allow DHCPv6 to append the delegated prefix information to accounting start and stop messages. When accounting is configured for a DHCPv6 pool, accounting interim packets are sent to broadband sessions after binding is provided from the pool.

Forced Release of a Binding

The DHCPv6 server maintains an automatic binding table in memory to track the assignment of some configuration parameters, such as prefixes between the server and its clients. The automatic bindings can be stored permanently in the database agent, which can be, for example, a remote TFTP server or local NVRAM file system.

DHCPv6 invokes a routine when the virtual interface used by PPP terminates. This routine automatically releases any delegated prefix bindings associated with the PPP virtual interface that is being terminated.

When a PPP virtual interface terminates, the routine runs through the full table of DHCPv6 bindings checking for the matching interface. Because PPP uses a virtual interface, this subroutine clears any related lease information when the PPP connection terminates.


Note

In IPv6 broadband deployment using DHCPv6, you must enable release of prefix bindings associated with a PPP virtual interface using the ipv6 dhcp binding track ppp command. This ensures that DHCPv6 bindings are tracked together with PPP sessions, and in the event of DHCP REBIND failure, the client initiates DHCPv6 negotiation again.

Delegated-IPv6-Prefix

The Delegated-IPv6-Prefix attribute calls DHCPv6 to parse and store AAA attribute information. PPP sends the accounting start and stop messages for PPP sessions.

The following is an example of a Delegated-IPv6-Prefix attribute:

cisco-avpair = ipv6:delegated-prefix=2001:DB8::/64


Note

The Delegated-IPv6-Prefix attribute does not support the Cisco VSA format. If you try add this attribute in the cisco-vsa format in the profile, the RADIUS server response fails. Use only the IETF attribute for Delegated-IPv6-Prefix.

PPP IPv6 Accounting Delay Enhancements

This feature enhances accounting records for dual-stack networks. It ensures that a unique IPv6 address is assigned to PPP IPv6 and IPv4 sessions for IP addresses that are received from RADIUS.

When this feature is enabled, it automatically creates a database to hold new incoming access-accept responses from RADIUS. The access-accept responses in this database are then checked for duplicates of a specific set of attributes. If the attributes are already present in the database, then the RADIUS server has already offered them to an existing session; therefore, the new session is immediately removed and a stop-record message sent. If none of the specific set of attributes are in the database, they are immediately added to the database, and the session proceeds normally. When the session is removed, the entries in the database are also removed.

The following RADIUS attributes are tracked in the database and checked at access-accept time:

  • Framed-IPv6-Prefix

  • Delegated-IPv6-Prefix

The attributes are available as standard RFC-defined binary format, or as Cisco VSAs. (The Delegated-IPv6-Prefix attribute currently does not have a VSA definition in AAA.)

How to Configure PPP for IPv6

Enabling the Sending of Accounting Start and Stop Messages

SUMMARY STEPS

    1.    enable

    2.    configure terminal

    3.    ipv6 dhcp pool poolname

    4.    accounting mlist


DETAILED STEPS
     Command or ActionPurpose
    Step 1 enable


    Example: 
    Device> enable
     

    Enables privileged EXEC mode.

    • Enter your password if prompted.

     
    Step 2 configure terminal


    Example: 
    Device# configure terminal
     

    Enters global configuration mode.

     
    Step 3 ipv6 dhcp pool poolname


    Example: 
    Device(config)# ipv6 dhcp pool pool1
     

    Configures a DHCP for IPv6 configuration information pool and enters DHCP for IPv6 pool configuration mode.

     
    Step 4 accounting mlist


    Example: 
    Device(config-dhcp)# accounting list1
     

    Enables accounting start and stop messages to be sent.

     

    Removing Delegated Prefix Bindings

    Perform this task to release any delegated prefix bindings associated with the PPP virtual interface that is being terminated.

    SUMMARY STEPS

      1.    enable

      2.    configure terminal

      3.    interface type number

      4.    ipv6 dhcp bindings track ppp


    DETAILED STEPS
       Command or ActionPurpose
      Step 1 enable


      Example: 
      Device> enable
       

      Enables privileged EXEC mode.

      • Enter your password if prompted.

       
      Step 2 configure terminal


      Example: 
      Device# configure terminal
       

      Enters global configuration mode.

       
      Step 3 interface type number


      Example: 
      Device(config)# interface VirtualAccess2.2
       

      Specifies an interface type and number, and places the router in interface configuration mode.

       
      Step 4 ipv6 dhcp bindings track ppp


      Example: 
      Device(config-if)# ipv6 dhcp bindings track ppp
       

      Releases any delegated prefix leases associated with the PPP virtual interface that is being terminated.

       

      Configuring PPP IPv6 Accounting Delay Enhancements

      SUMMARY STEPS

        1.    enable

        2.    configure terminal

        3.    ppp unique address access-accept


      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 ppp unique address access-accept


        Example:
        Router(config)# ppp unique address access-accept
         

        Tracks duplicate addresses received from RADIUS and creates a standalone database.

         

        Configuration Examples for PPP for IPv6

        Example: Enabling the Sending of Accounting Start and Stop Messages

        This example shows how to enable a device to send accounting start and stop messages. 

        Device(config)# ipv6 dhcp pool pool1
Device(config-dhcp)# accounting list1

        Additional References

        Related Documents

        Related Topic

        Document Title

        IPv6 addressing and connectivity

        IPv6 Configuration Guide

        Cisco IOS commands

        Cisco IOS Master Commands List, All Releases

        IPv6 commands

        Cisco IOS IPv6 Command Reference

        Cisco IOS IPv6 features

        Cisco_​IOS_​IPv6_​Feature_​Mapping

        Standards and RFCs

        Standard/RFC

        Title

        RFCs for IPv6

        MIBs

        MIB

        MIBs Link

        To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:

        http:/​/​www.cisco.com/​go/​mibs

        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 for IPv6

        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 for IPv6

        Feature Name

        Releases

        Feature Information

        PPP Enhancement for Broadband IPv6

        Cisco IOS XE Release 2.5

        IPv6 supports this feature.

        The following commands were introduced or modified: accounting, ipv6 dhcp bindings track ppp, ipv6 dhcp pool.

        PPP IPv6 Accounting Delay Enhancements

        Cisco IOS XE Release 3.2S

        IPv6 supports this feature.

        The following commands were introduced or modified: ppp unique address accept-access.

        SSO/ISSU Support for Per-User IPv6 ACL for PPP Sessions

        Cisco IOS XE Release 3.2.1S

        IPv6 supports this feature.

        No commands were introduced or modified.