IP Routing: BGP Configuration Guide, Cisco IOS XE Release 3S
IPv6 Routing: Multiprotocol BGP Extensions for IPv6
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IPv6 Routing: Multiprotocol BGP Extensions for IPv6

Contents

IPv6 Routing: Multiprotocol BGP Extensions 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 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 IPv6 Routing: Multiprotocol BGP Extensions for IPv6

Multiprotocol BGP Extensions for IPv6

Multiprotocol BGP is the supported Exterior Gateway Protocol (EGP) for IPv6. Multiprotocol BGP extensions for IPv6 supports many of the same features and functionality as IPv4 BGP. IPv6 enhancements to multiprotocol BGP include support for an IPv6 address family and Network Layer Reachability Information (NLRI) and next hop (the next device in the path to the destination) attributes that use IPv6 addresses.

How to Implement Multiprotocol BGP for IPv6

Configuring an IPv6 BGP Routing Process and BGP Router ID

Perform this task to configure an IPv6 BGP routing process and an optional BGP router ID for a BGP-speaking device.

BGP uses a router ID to identify BGP-speaking peers. The BGP router ID is 32-bit value that is often represented by an IPv4 address. By default, the router ID is set to the IPv4 address of a loopback interface on the device. If no loopback interface is configured on the device, then the software chooses the highest IPv4 address configured to a physical interface on the device to represent the BGP router ID.

When configuring BGP on a device that is enabled only for IPv6 (that is, the device does not have an IPv4 address), you must manually configure the BGP router ID for the device. The BGP router ID, which is represented as a 32-bit value using an IPv4 address syntax, must be unique to the BGP peers of the device.

SUMMARY STEPS

    1.    enable

    2.    configure terminal

    3.    router bgp as-number

    4.    no bgp default ipv4-unicast

    5.    bgp router-id ip-address


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 router bgp as-number


    Example:
    Device(config)# router bgp 65000
     

    Configures a BGP routing process, and enters router configuration mode for the specified routing process.

     
    Step 4 no bgp default ipv4-unicast


    Example:
    Device(config-router)# no bgp default ipv4-unicast
     

    Disables the IPv4 unicast address family for the BGP routing process specified in the previous step.

    Note    Routing information for the IPv4 unicast address family is advertised by default for each BGP routing session configured with the neighbor remote-as command unless you configure the no bgp default ipv4-unicast command before configuring the neighbor remote-as command.
     
    Step 5 bgp router-id ip-address


    Example:
    Device(config-router)# bgp router-id 192.168.99.70
     

    (Optional) Configures a fixed 32-bit router ID as the identifier of the local device running BGP.

    Note    Configuring a router ID using the bgp router-id command resets all active BGP peering sessions.
     

    Configuring IPv6 Multiprotocol BGP Between Two Peers

    By default, neighbors that are defined using the neighbor remote-as command in router configuration mode exchange only IPv4 unicast address prefixes. To exchange other address prefix types, such as IPv6 prefixes, neighbors must also be activated using the neighbor activate command in address family configuration mode for the other prefix types, as shown for IPv6 prefixes.

    SUMMARY STEPS

      1.    enable

      2.    configure terminal

      3.    router bgp as-number

      4.    neighbor {ip-address | ipv6-address [%] | peer-group-name} remote-as autonomous-system-number [alternate-as autonomous-system-number ...]

      5.    address-family ipv6 [unicast | multicast]

      6.    neighbor {ip-address | peer-group-name | ipv6-address %} activate


    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 router bgp as-number


      Example:
      Device(config)# router bgp 65000
       

      Enters router configuration mode for the specified routing process.

       
      Step 4 neighbor {ip-address | ipv6-address [%] | peer-group-name} remote-as autonomous-system-number [alternate-as autonomous-system-number ...]


      Example:
      Device(config-router)# neighbor 2001:DB8:0:CC00::1 remote-as 64600
       

      Adds the IPv6 address of the neighbor in the specified autonomous system to the IPv6 multiprotocol BGP neighbor table of the local device.

       
      Step 5 address-family ipv6 [unicast | multicast]


      Example:
      Device(config-router)# address-family ipv6
       

      Specifies the IPv6 address family and enters address family configuration mode.

      • The unicast keyword specifies the IPv6 unicast address family. By default, the device is placed in configuration mode for the IPv6 unicast address family if a keyword is not specified with the address-family ipv6 command.
      • The multicast keyword specifies IPv6 multicast address prefixes.
       
      Step 6 neighbor {ip-address | peer-group-name | ipv6-address %} activate


      Example:
      Device(config-router-af)# neighbor 2001:DB8:0:CC00::1 activate
       

      Enables the neighbor to exchange prefixes for the IPv6 address family with the local device.

       

      Advertising IPv4 Routes Between IPv6 BGP Peers

      If an IPv6 network is connecting two separate IPv4 networks, IPv6 can be used to advertise the IPv4 routes. Configure the peering using the IPv6 addresses within the IPv4 address family. Set the next hop with a static route or with an inbound route map because the advertised next hop will usually be unreachable. Advertising IPv6 routes between two IPv4 peers is also possible using the same model.

      SUMMARY STEPS

        1.    enable

        2.    configure terminal

        3.    router bgp as-number

        4.    neighbor peer-group-name peer-group

        5.    neighbor {ip-address | ipv6-address[%] | peer-group-name} remote-as autonomous-system-number [alternate-as autonomous-system-number ...]

        6.    address-family ipv4 [mdt | multicast | tunnel | unicast [vrf vrf-name] | vrf vrf-name]

        7.    neighbor ipv6-address peer-group peer-group-name

        8.    neighbor {ip-address | peer-group-name | ipv6-address [%]} route-map map-name {in | out}

        9.    exit

        10.    exit

        11.    route-map map-tag [permit | deny] [sequence-number]

        12.    set ip next-hop ip-address [... ip-address] [peer-address]


      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 router bgp as-number


        Example:
        Device(config)# router bgp 65000
         

        Enters router configuration mode for the specified routing process.

         
        Step 4 neighbor peer-group-name peer-group


        Example:
        Device(config-router)# neighbor 6peers peer-group
         

        Creates a multiprotocol BGP peer group.

         
        Step 5 neighbor {ip-address | ipv6-address[%] | peer-group-name} remote-as autonomous-system-number [alternate-as autonomous-system-number ...]


        Example:
        Device(config-router)# neighbor 6peers remote-as 65002
         

        Adds the IPv6 address of the neighbor in the specified autonomous system to the IPv6 multiprotocol BGP neighbor table of the local device.

         
        Step 6 address-family ipv4 [mdt | multicast | tunnel | unicast [vrf vrf-name] | vrf vrf-name]


        Example:
        Device(config-router)# address-family ipv4
         

        Enters address family configuration mode to configure a routing session using standard IPv4 address prefixes.

         
        Step 7 neighbor ipv6-address peer-group peer-group-name


        Example:
        Device(config-router-af)# neighbor 2001:DB8:1234::2 peer-group 6peers
         

        Assigns the IPv6 address of a BGP neighbor to a peer group.

         
        Step 8 neighbor {ip-address | peer-group-name | ipv6-address [%]} route-map map-name {in | out}


        Example:
        Device(config-router-af)# neighbor 6peers route-map rmap out 
         

        Applies a route map to incoming or outgoing routes.

        • Changes to the route map will not take effect for existing peers until the peering is reset or a soft reset is performed. Using the clear bgp ipv6 command with the soft and in keywords will perform a soft reset.
         
        Step 9 exit


        Example:
        Device(config-router-af)# exit
         

        Exits address family configuration mode, and returns the device to router configuration mode.

         
        Step 10 exit


        Example:
        Device(config-router)# exit
         

        Exits router configuration mode, and returns the device to global configuration mode.

         
        Step 11 route-map map-tag [permit | deny] [sequence-number]


        Example:
        Device(config)# route-map rmap permit 10
         

        Defines a route map and enters route-map configuration mode.

         
        Step 12 set ip next-hop ip-address [... ip-address] [peer-address]


        Example:
        Device(config-route-map)# set ip next-hop 10.21.8.10
         

        Overrides the next hop advertised to the peer for IPv4 packets.

         

        Clearing External BGP Peers

        SUMMARY STEPS

          1.    enable

          2.    clear bgp ipv6 {unicast | multicast} external [soft] [in | out]

          3.    clear bgp ipv6 {unicast | multicast} peer-group name


        DETAILED STEPS
           Command or ActionPurpose
          Step 1 enable


          Example:
          Device> enable
           

          Enables privileged EXEC mode.

          • Enter your password if prompted.

           
          Step 2 clear bgp ipv6 {unicast | multicast} external [soft] [in | out]


          Example:
          Device# clear bgp ipv6 unicast external soft in
           

          Clears external IPv6 BGP peers.

           
          Step 3 clear bgp ipv6 {unicast | multicast} peer-group name


          Example:
          Device# clear bgp ipv6 unicast peer-group marketing
           

          Clears all members of an IPv6 BGP peer group.

           

          Configuration Examples for Multiprotocol BGP for IPv6

          Example: Configuring a BGP Process, BGP Router ID, and IPv6 Multiprotocol BGP Peer

          The following example enables IPv6 globally, configures a BGP process, and establishes a BGP router ID. Also, the IPv6 multiprotocol BGP peer 2001:DB8:0:CC00::1 is configured and activated.

          ipv6 unicast-routing
          !
          router bgp 65000
           no bgp default ipv4-unicast
           bgp router-id 192.168.99.70
           neighbor 2001:DB8:0:CC00::1 remote-as 64600
           address-family ipv6 unicast
            neighbor 2001:DB8:0:CC00::1 activate

          Example: Configuring an IPv6 Multiprotocol BGP Peer Group

          The following example configures the IPv6 multiprotocol BGP peer group named group1:

          router bgp 65000
          no bgp default ipv4-unicast
          neighbor group1 peer-group
          neighbor 2001:DB8:0:CC00::1 remote-as 64600
          address-family ipv6 unicast
           neighbor group1 activate
           neighbor 2001:DB8:0:CC00::1 peer-group group1

          Example: Advertising Routes into IPv6 Multiprotocol BGP

          The following example injects the IPv6 network 2001:DB8::/24 into the IPv6 unicast database of the local device. (BGP checks that a route for the network exists in the IPv6 unicast database of the local device before advertising the network.)

          router bgp 65000
           no bgp default ipv4-unicast
          address-family ipv6 unicast
            network 2001:DB8::/24

          Example: Configuring a Route Map for IPv6 Multiprotocol BGP Prefixes

          The following example configures the route map named rtp to permit IPv6 unicast routes from network 2001:DB8::/24 if they match the prefix list named cisco:

          router bgp 64900
          no bgp default ipv4-unicast
          neighbor 2001:DB8:0:CC00::1 remote-as 64700
          address-family ipv6 unicast
           neighbor 2001:DB8:0:CC00::1 activate
           neighbor 2001:DB8:0:CC00::1 route-map rtp in
          ipv6 prefix-list cisco seq 10 permit 2001:DB8::/24
          route-map rtp permit 10
           match ipv6 address prefix-list cisco

          Example: Redistributing Prefixes into IPv6 Multiprotocol BGP

          The following example redistributes RIP routes into the IPv6 unicast database of the local device:

          router bgp 64900
          no bgp default ipv4-unicast
          address-family ipv6 unicast
           redistribute rip

          Example: Advertising IPv4 Routes Between IPv6 Peers

          The following example advertises IPv4 routes between IPv6 peers when the IPv6 network is connecting two separate IPv4 networks. Peering is configured using IPv6 addresses in the IPv4 address family configuration mode. The inbound route map named rmap sets the next hop because the advertised next hop is likely to be unreachable.

          router bgp 65000
          !
           neighbor 6peers peer-group
           neighbor 2001:DB8:1234::2 remote-as 65002
           address-family ipv4
           neighbor 6peers activate
           neighbor 6peers soft-reconfiguration inbound
           neighbor 2001:DB8:1234::2 peer-group 6peers
           neighbor 2001:DB8:1234::2 route-map rmap in
          !   
          route-map rmap permit 10
           set ip next-hop 10.21.8.10

          Additional References

          Related Documents

          Related Topic

          Document Title

          IPv6 addressing and connectivity

          IPv6 Configuration Guide

          Cisco IOS commands

          Cisco IOS Master Command 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

          IPv6 RFCs

          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 IPv6 Routing Multiprotocol BGP Extensions 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 IPv6 Routing Multiprotocol BGP Extensions for IPv6

          Feature Name

          Releases

          Feature Information

          IPv6 Routing: Multiprotocol BGP Extensions for IPv6

          Cisco IOS XE Release 2.1

          Multiprotocol BGP extensions for IPv6 supports the same features and functionality as IPv4 BGP.