MPLS VPN Load Balancing Support for Inter-AS and CSC VPNs

The MPLS VPN Load Balancing Support for Inter-AS and CSC VPNs feature allows MPLS VPN interautonomous (Inter-AS) and MPLS VPN Carrier Supporting Carrier (CSC) networks to load share traffic between adjacent label switch routers (LSRs) that are connected by multiple links. The LSRs can be a pair of Autonomous System Boundary Routers (ASBRs) or a CSC-provider edge (PE) and a CSC-customer edge (CE) device. Using directly connected loopback peering allows load sharing at the Interior Gateway Protocol (IGP) level so only one Border Gateway Protocol (BGP) session is needed between the LSRs. No other label distribution mechanism is needed between the adjacent LSRs except BGP.

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.

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Prerequisites for MPLS VPN Load Balancing Support for Inter-AS and CSC VPNs

Ensure that your Multiprotocol Label Switching (MPLS) virtual private network (VPN) network, including MPLS VPN interautonomous system (Inter-AS) or Carrier Supporting Carrier (CSC), is configured and working properly.

Restrictions for MPLS VPN Load Balancing Support for Inter-AS and CSC VPNs

Load sharing using directly connected loopback peering does not apply to Carrier Supported Carrier (CSC) networks that use the Label Distribution Protocol (LDP) and an Interior Gateway Protocol (IGP) to distribute routes and Multiprotocol Label Switching (MPLS) labels.

The software does not support load balancing in interautonomous system (Inter-AS) and CSC when there are multiple links between provider edge (PE) or Autonomous System Boundary Router (ASBR) devices.

When you configure static routes in an MPLS or MPLS virtual private network (VPN) environment, some variations of the ip route and ip route vrf commands are not supported. These variations of the commands are not supported in Cisco software releases that support the Tag Forwarding Information Base (TFIB. The TFIB cannot resolve prefixes when the recursive route over which the prefixes travel disappears and then reappears. However, the command variations are supported in Cisco software releases that support the MPLS Forwarding Infrastructure (MFI). Use the following guidelines when configuring static routes.

Supported Static Routes in an MPLS Environment

The following ip route command is supported when you configure static routes in an MPLS environment:

  • ip route destination-prefix mask interface next-hop-address

The following ip route commands are supported when you configure static routes in an MPLS environment and configure load sharing with static nonrecursive routes and a specific outbound interface:

  • ip route destination-prefix mask interface1 next-hop1

  • ip route destination-prefix mask interface2 next-hop2

Unsupported Static Routes in an MPLS Environment That Uses the TFIB

The following ip route command is not supported when you configure static routes in an MPLS environment:

  • ip route destination-prefix mask next-hop-address

The following ip route command is not supported when you configure static routes in an MPLS VPN environment and enable load sharing where the next hop can be reached through two paths:

  • ip route destination-prefix mask next-hop-address

The following ip route command is not supported when you configure static routes in an MPLS VPN environment and enable load sharing where the destination can be reached through two next hops:

  • ip route destination-prefix mask next-hop1

  • ip route destination-prefix mask next-hop2

Use the interface and next-hop arguments when specifying static routes.

Supported Static Routes in an MPLS VPN Environment

The following ip route vrf commands are supported when you configure static routes in an MPLS VPN environment, and the next hop and interface are associated with the same virtual routing and forwarding (VRF) instance:

  • ip route vrf vrf-name destination-prefix mask next-hop-address

  • ip route vrf vrf-name destination-prefix mask interface next-hop-address

  • ip route vrf vrf-name destination-prefix mask interface1 next-hop1

  • ip route vrf vrf-name destination-prefix mask interface2 next-hop2

The following ip route vrf commands are supported when you configure static routes in an MPLS VPN environment, and the next hop is in the global table in the MPLS cloud in the global routing table. For example, these commands are supported when the next hop is pointing to the internet gateway.

  • ip route vrf vrf-name destination-prefix mask next-hop-address global

  • ip route vrf vrf-name destination-prefix mask interface next-hop-address (This command is supported when the next hop and the interface are in the core.)

The following ip route commands are supported when you configure static routes in an MPLS VPN environment and enable load sharing with static nonrecursive routes and a specific outbound interfaces:

  • ip route destination-prefix mask interface1 next-hop1

  • ip route destination-prefix mask interface2 next-hop2

Unsupported Static Routes in an MPLS VPN Environment That Uses the TFIB

The following ip route command is not supported when you configure static routes in an MPLS VPN environment, the next hop is in the global table in the MPLS cloud within the core, and you enable load sharing where the next hop can be reached through two paths:

  • ip route vrf destination-prefix mask next-hop-address global

The following ip route commands are not supported when you configure static routes in an MPLS VPN environment, the next hop is in the global table in the MPLS cloud within the core, and you enable load sharing where the destination can be reached through two next hops:

  • ip route vrf destination-prefix mask next-hop1 global

  • ip route vrf destination-prefix mask next-hop2 global

The following ip route vrf commands are not supported when you configure static routes in an MPLS VPN environment, and the next hop and interface are in the same VRF:

  • ip route vrf vrf-name destination-prefix mask next-hop1

  • ip route vrf vrf-name destination-prefix mask next-hop2

Supported Static Routes in an MPLS VPN Environment Where the Next Hop Resides in the Global Table on the CE Device

The following ip route vrf command is supported when you configure static routes in an MPLS VPN environment, and the next hop is in the global table on the customer edge (CE) side. For example, the following command is supported when the destination-prefix is the CE device’s loopback address, as in external Border Gateway Protocol (eBGP) multihop cases.

  • ip route vrf vrf-name destination-prefix mask interface next-hop-address

The following ip route commands are supported when you configure static routes in an MPLS VPN environment, the next hop is in the global table on the CE side, and you enable load sharing with static nonrecursive routes and a specific outbound interfaces:

  • ip route destination-prefix mask interface1 nexthop1

  • ip route destination-prefix mask interface2 nexthop2

Information About MPLS VPN Load Balancing Support for Inter-AS and CSC VPNs

Load Sharing Using Directly Connected Loopback Peering

You use the MPLS VPN Load Balancing Support for Inter-AS and CSC VPN feature to load share traffic between adjacent label switched routers (LSRs) that are connected by multiple links. The LSRs could be a pair of Autonomous System Boundary Routers (ASBRs) or a carrier supporting carrier provider edge (CSC-PE) and a CSC-customer edge (CE).

Using directly connected loopback peering allows load sharing at the Interior Gateway Protocol (IGP) level so only one Border Gateway Protocol (BGP) session is needed between the LSRs. No other label distribution mechanism is needed between the adjacent LSRs except BGP.

Directly connected loopback peering enables load sharing of traffic as follows:

  • A BGP session is established, using the loopback addresses of the LSRs.

  • Multiprotocol Label Switching (MPLS) is enabled on the connecting links.

  • Multiple static routes to the loopback address of the adjacent LSR allow IGP load sharing.

  • The outgoing label to the loopback address of the adjacent LSR is an implicit null label and is inferred by the LSR.

  • Because IGP load sharing is enabled on the loopback address of the adjacent LSR, any traffic destined to a prefix that is learned over the BGP session (and recurses over the loopback) is load shared.

How to Configure MPLS VPN Load Balancing Support for Inter-AS and CSC VPN

Configuring Directly Connected Loopback Peering for MPLS VPN Inter-AS using ASBRs to Exchange VPN-IPv4 Addresses

This section describes the following tasks you need to do to configure peering of loopback interfaces of directly connected Autonomous System Boundary Routers (ASBRs):

The figure below shows the loopback configuration for directly connected ASBR1 and ASBR2. This configuration is used as the example in the tasks that follow.

Figure 1. Loopback Interface Configuration for Directly Connected ASBR1 and ASBR2

Configuring Loopback Interface Addresses for Directly Connected ASBRs

Perform this task to configure loopback interface addresses for directly connected Autonomous System Boundary Routers (ASBRs).


Note

Loopback addresses need to be configured for each directly connected ASBR. That is, configure a loopback address for ASBR1 and for ASBR2 in the example shown in the figure above.

SUMMARY STEPS

    1.    enable

    2.    configure terminal

    3.    interface loopback interface- number

    4.    ip address ip-address mask [secondary]

    5.    end


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 loopback interface- number


    Example:
    Device(config)# interface loopback 0
     

    Configures a software-only virtual interface that emulates an interface that is always up and enters interface configuration mode.

    • The interface-number argument is the number of the loopback interface that you want to create or configure. There is no limit on the number of loopback interfaces that you can create.

     
    Step 4 ip address ip-address mask [secondary]


    Example:
    Device(config-if)# ip address 10.10.10.10 255.255.255.255
     

    Sets a primary or secondary IP address for an interface.

    • The ip-address argument is the IP address.

    • The mask argument is the mask for the associated IP subnet.

    • The secondary keyword specifies that the configured address is a secondary IP address. If this keyword is omitted, the configured address is the primary IP address.

     
    Step 5 end


    Example:
    Device(config-if)# end
     

    Exits to privileged EXEC mode.

     

    Configuring /32 Static Routes to the eBGP Neighbor Loopback

    Perform this task to configure /32 static routes to the external Border Gateway Protocol (eBGP) neighbor loopback.


    Note

    You need to configure /32 static routes on each of the directly connected ASBRs.

    SUMMARY STEPS

      1.    enable

      2.    configure terminal

      3.    ip route prefix mask {ip-address | interface-type interface-number [ip-address]} [distance] [name] [permanent] [tag tag]

      4.    end


    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 ip route prefix mask {ip-address | interface-type interface-number [ip-address]} [distance] [name] [permanent] [tag tag]


      Example:
      Device(config)# ip route 10.20.20.20 255.255.255.255 Ethernet 1/0 172.16.0.1
       

      Establishes static routes.

      • The prefix argument is the IP route prefix for the destination.

      • The mask argument is the prefix mask for the destination.

      • The ip-address argument is the IP address of the next hop that you can use to reach the specified network.

      • The interface-type and interface-number arguments are the network interface type and interface number.

      • The distance argument is an administrative distance.

      • The name argument applies a name to the specified route.

      • The permanent keyword specifies that the route is not to be removed, even if the interface shuts down.

      • The tag tag keyword and argument name a tag value that can be used as a “match” value for controlling redistribution through the use of route maps.

       
      Step 4 end


      Example:
      Device(config)# end
       

      Exits to privileged EXEC mode.

       

      Configuring Forwarding on Connecting Loopback Interfaces

      Perform this task to configure forwarding on the connecting loopback interfaces.

      This task is required for sessions between loopbacks. In the “Configuring /32 Static Routes to the eBGP Neighbor Loopback" section, Ethernet 1/0 and Ethernet 0/0 are the connecting interfaces.

      SUMMARY STEPS

        1.    enable

        2.    configure terminal

        3.    interface type slot/port

        4.    mpls bgp forwarding

        5.    exit

        6.    Repeat Steps 3 and 4 for another connecting interface (Ethernet 0/0).

        7.    end


      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 slot/port


        Example:
        Device(config)# interface ethernet 1/0
         

        Configures an interface type and enters interface configuration mode.

        • The type argument is the type of interface to be configured.

        • The slot argument is the slot number. Refer to the appropriate hardware manual for slot and port information.

        • The /port argument is the port number. Refer to the appropriate hardware manual for slot and port information.

         
        Step 4 mpls bgp forwarding


        Example:
        Device(config-if)# mpls bgp forwarding
         

        Configures the Border Gateway Protocol (BGP) to enable Multiprotocol Label Switching (MPLS) forwarding on connecting interfaces.

         
        Step 5 exit


        Example:
        Device(config-if)# exit
         

        Exits to global configuration mode.

         
        Step 6 Repeat Steps 3 and 4 for another connecting interface (Ethernet 0/0).    
        Step 7 end


        Example:
        Device(config)# end
         

        Exits to privileged EXEC mode.

         

        Configuring an eBGP Session Between the Loopbacks

        Perform this task to configure an external Border Gateway Protocol (eBGP) session between the loopbacks.


        Note

        You need to configure an eBGP session between loopbacks on each directly connected Autonomous System Boundary Router (ASBR).

        SUMMARY STEPS

          1.    enable

          2.    configure terminal

          3.    router bgp as-number

          4.    no bgp default route-target filter

          5.    neighbor {ip-address | peer-group-name} remote-as as-number

          6.    neighbor {ip-address | peer-group-name} disable-connected-check

          7.    neighbor {ip-address | ipv6-address | peer-group-name} update-source interface-type interface-number

          8.    address-family vpnv4 [unicast]

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

          10.    neighbor {ip-address | peer-group-name} send-community [both | standard extended]

          11.    end


        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 200
           

          Configures the BGP routing process.

          • The as-number indicates the number of an autonomous system that identifies the device to other BGP routers and tags the routing information passed along.

           
          Step 4 no bgp default route-target filter


          Example:
          Device(config)# no bgp default route-target filter
           

          Disables BGP route-target filtering, and enters router configuration mode.

          • All received BGP VPN-IPv4 routes are accepted by the device.

           
          Step 5 neighbor {ip-address | peer-group-name} remote-as as-number


          Example:
          Device(config-router)# neighbor 10.20.20.20 remote-as 100
           

          Adds an entry to the BGP or multiprotocol BGP neighbor table.

          • The ip-address argument is the IP address of the neighbor.

          • The peer-group-name argument is the name of a BGP peer group.

          • The as-number argument is the autonomous system to which the neighbor belongs.

           
          Step 6 neighbor {ip-address | peer-group-name} disable-connected-check


          Example:
          Device(config-router)# neighbor 10.20.20.20 disable-connected-check
           

          Allows peering between loopbacks.

          • The ip-address argument is the IP address of the neighbor.

          • The peer-group-name argument is the name of a BGP peer group.

           
          Step 7 neighbor {ip-address | ipv6-address | peer-group-name} update-source interface-type interface-number


          Example:
          Device(config-router)# neighbor 10.20.20.20 update-source Loopback 0
           

          Allows BGP sessions to use any operational interface for TCP connections.

          • The ip-address argument is the IPv4 address of the BGP-speaking neighbor.

          • The ipv6-address argument is the IPv6 address of the BGP-speaking neighbor.

          This argument must be in the form documented in RFC 2373, where the address is specified in hexadecimal using 16-bit values between colons.

          • The peer-group-name argument is the name of a BGP peer group.

          • The interface-type argument is the interface type.

          • The interface-number argument is the interface number.

           
          Step 8 address-family vpnv4 [unicast]


          Example:
          Device(config-router)# address-family vpnv4
           

          Enters address family configuration mode for configuring routing protocols such as BGP, Routing Information Protocol (RIP), and static routing.

          • The unicast keyword specifies unicast prefixes.

           
          Step 9 neighbor {ip-address | peer-group-name | ipv6-address} activate


          Example:
          Device(config-router-af)# neighbor 10.20.20.20 activate
           

          Enables the exchange of information with a BGP neighbor.

          • The ip-address argument is the IP address of the neighboring device.

          • The peer-group-name argument is the name of a BGP peer group.

          • The ipv6-address argument is the IPv6 address of the BGP-speaking neighbor.

          Note   

          This argument must be in the form documented in RFC 2373, where the address is specified in hexadecimal using 16-bit values between colons.

           
          Step 10 neighbor {ip-address | peer-group-name} send-community [both | standard extended]


          Example:
          Device(config-router-af)# neighbor 10.20.20.20 send-community extended
           

          Specifies that a communities attribute should be sent to a BGP neighbor.

          • The ip-address argument is the IP address of the neighboring device.

          • The peer-group-name argument is the name of a BGP peer group.

          • The both keyword specifies that both standard and extended communities will be sent.

          • The standard keyword specifies that only standard communities will be sent.

          • The extended keyword specifies that only extended communities will be sent.

           
          Step 11 end


          Example:
          Device(config)# end
           

          Exits to privileged EXEC mode.

           

          Verifying That Load Sharing Occurs Between Loopbacks

          Perform this task to verify that load sharing occurs between loopbacks. You need to ensure that the Multiprotocol Label Switching (MPLS) Label Forwarding Information Base (LFIB) entry for the neighbor route lists the available paths and interfaces.

          SUMMARY STEPS

            1.    enable

            2.    show mpls forwarding-table {mask | length} | labels label [network label] | interface interface | next-hop address | lsp-tunnel [tunnel-id]] [vrf vrf-name] [detail]

            3.    disable


          DETAILED STEPS
             Command or ActionPurpose
            Step 1 enable


            Example:
            Device> enable
             

            (Optional) Enables privileged EXEC mode.

            • Enter your password if prompted.

             
            Step 2 show mpls forwarding-table {mask | length} | labels label [network label] | interface interface | next-hop address | lsp-tunnel [tunnel-id]] [vrf vrf-name] [detail]


            Example:
            Device# show mpls forwarding-table
             

            Displays the contents of the MPLS LFIB.

            • Enter an optional keyword or argument if desired.

             
            Step 3 disable


            Example:
            Device# disable
             

            Exits to user EXEC mode.

             

            Configuring Directly Connected Loopback Peering for MPLS VPN Inter-AS Using ASBRs to Exchange IPv4 Routes and Labels

            The following sections describe how to configure peering of loopback interfaces of directly connected Autonomous System Boundary Routers (ASBRs) to achieve load sharing in an interautonomous system network:

            The figure below shows the loopback configuration for directly connected ASBR1 and ASBR2. This configuration is used as the example in the tasks that follow.

            Figure 2. Loopback Interface Configuration for Directly Connected ASBR1 and ASBR2

            Configuring Loopback Interface Addresses for Directly Connected ASBRs


            Note

            Loopback addresses need to be configured for each directly connected Autonomous System Boundary Router (ASBR). That is, configure a loopback address for ASBR1 and for ASBR2 as in the example shown in the figure above.

            SUMMARY STEPS

              1.    enable

              2.    configure terminal

              3.    interface loopback interface number

              4.    ip address ip-address [mask [secondary]]

              5.    end


            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 loopback interface number


              Example:
              Device(config)# interface loopback 0
               

              Configures a software-only virtual interface that emulates an interface that is always up and enters interface configuration mode.

              • The interface-number argument is the number of the loopback interface that you want to create or configure. There is no limit on the number of loopback interfaces that you can create.

               
              Step 4 ip address ip-address [mask [secondary]]


              Example:
              Device(config-if)# ip address 10.10.10.10 255.255.255.255
               

              Sets a primary or secondary IP address for an interface.

              • The ip-address argument is the IP address.

              • The mask argument is the mask for the associated IP subnet.

              • The secondary keyword specifies that the configured address is a secondary IP address. If this keyword is omitted, the configured address is the primary IP address.

               
              Step 5 end


              Example:
              Device(config-if)# end
               

              Exits to privileged EXEC mode.

               

              Configuring /32 Static Routes to the eBGP Neighbor Loopback

              Perform this task to configure /32 static routes to the external Border Gateway Protocol (eBGP) neighbor loopback.


              Note

              You need to configure /32 static routes on each of the directly connected Autonomous System Boundary Routers (ASBRs).

              SUMMARY STEPS

                1.    enable

                2.    configure terminal

                3.    ip route prefix mask {ip-address | interface-type interface-number [ip-address]} [distance] [name] [permanent] [tag tag]

                4.    end


              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 ip route prefix mask {ip-address | interface-type interface-number [ip-address]} [distance] [name] [permanent] [tag tag]


                Example:
                Device(config)# ip route 10.20.20.20 255.255.255.255 Ethernet 1/0 172.16.0.1
                 

                Establishes static routes.

                • The prefix argument is the IP route prefix for the destination.

                • The mask argument is the prefix mask for the destination.

                • The ip-address argument is the IP address of the next hop that you can use to reach the specified network.

                • The interface-type and interface-number arguments are the network interface type and interface number.

                • The distance argument is an administrative distance.

                • The name argument applies a name to the specified route.

                • The permanent keyword specifies that the route is not to be removed, even if the interface shuts down.

                • The tag tag keyword and argument name a tag value that can be used as a “match” value for controlling redistribution through the use of route maps.

                 
                Step 4 end


                Example:
                Device(config)# end
                 

                Exits to privileged EXEC mode.

                 

                Configuring Forwarding on Connecting Loopback Interfaces

                This task is required for sessions between loopbacks. In the “Configuring /32 Static Routes to the eBGP Neighbor Loopback” task, Ethernet1/0 and Ethernet0/0 are the connecting interfaces.

                SUMMARY STEPS

                  1.    enable

                  2.    configure terminal

                  3.    interface type slot/port

                  4.    mpls bgp forwarding

                  5.    exit

                  6.    Repeat Steps 3 and 4 for another connecting interface (Ethernet 0/0).

                  7.    end


                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 slot/port


                  Example:
                  Device(config)# interface ethernet 1/0
                   

                  Configures an interface type and enters interface configuration mode.

                  • The type argument is the type of interface to be configured.

                  • The slot argument is the slot number. Refer to the appropriate hardware manual for slot and port information.

                  • The /port argument is the port number. Refer to the appropriate hardware manual for slot and port information.

                   
                  Step 4 mpls bgp forwarding


                  Example:
                  Device(config-if)# mpls bgp forwarding
                   

                  Configures BGP to enable MPLS forwarding on connecting interfaces.

                   
                  Step 5 exit


                  Example:
                  Device(config-if)# exit
                   

                  Exits to global configuration mode.

                   
                  Step 6 Repeat Steps 3 and 4 for another connecting interface (Ethernet 0/0).    
                  Step 7 end


                  Example:
                  Device(config)# end
                   

                  Exits to privileged EXEC mode.

                   

                  Configuring an eBGP Session Between the Loopbacks


                  Note

                  You need to configure an external Border Gateway Protocol (eBGP) session between loopbacks on each directly connected Autonomous System Boundary Router (ASBR).

                  SUMMARY STEPS

                    1.    enable

                    2.    configure terminal

                    3.    router bgp as-number

                    4.    bgp log-neighbor-changes

                    5.    neighbor {ip-address | peer-group-name} remote-as as-number

                    6.    neighbor {ip-address | peer-group-name} disable-connected-check

                    7.    neighbor {ip-address | peer-group-name} ebgp-multihop [ttl]

                    8.    neighbor {ip-address | ipv6-address | peer-group-name} update-source interface-type interface-number

                    9.    address-family ipv4 [unicast] vrf vrf-name

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

                    11.    neighbor {ip-address | peer-group-name} send-community [both | standard | extended

                    12.    end


                  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 200
                     

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

                    • The as-number argument indicates the number of an autonomous system that identifies the device to other BGP routers and tags the routing information passed along.

                     
                    Step 4 bgp log-neighbor-changes


                    Example:
                    Device(config-router)# bgp log-neighbor-changes
                     

                    Enables logging of BGP neighbor resets.

                     
                    Step 5 neighbor {ip-address | peer-group-name} remote-as as-number


                    Example:
                    Device(config-router)# neighbor 10.20.20.20 remote-as 100
                     

                    Adds an entry to the BGP or multiprotocol BGP neighbor table.

                    • The ip-address argument is the IP address of the neighbor.

                    • The peer-group-name argument is the name of a BGP peer group.

                    • The as-number argument is the number of the autonomous system to which the neighbor belongs.

                     
                    Step 6 neighbor {ip-address | peer-group-name} disable-connected-check


                    Example:
                    Device(config-router)# neighbor 10.20.20.20 disable-connected-check
                     

                    Allows peering between loopbacks.

                    • The ip-address argument is the IP address of the neighbor.

                    • The peer-group-name argument is the name of a BGP peer group.

                     
                    Step 7neighbor {ip-address | peer-group-name} ebgp-multihop [ttl]


                    Example:
                    Device(config-router)# neighbor bb.bb.bb.bb ebgp-multihop 255
                     

                    Accepts and attempts BGP connections to external peers residing on networks that are not directly connected.

                    • The ip-address argument specifies the IP address of the BGP-speaking neighbor.

                    • The peer-group-name argument is the name of a BGP peer group.

                    • The ttl argument the time-to-live in the range from 1 to 255 hops.

                     
                    Step 8 neighbor {ip-address | ipv6-address | peer-group-name} update-source interface-type interface-number


                    Example:
                    Device(config-router)# neighbor 10.20.20.20 update-source Loopback 0
                     

                    Allows BGP sessions to use any operational interface for TCP connections.

                    • The ip-address argument is the IPv4 address of the BGP-speaking neighbor.

                    • The ipv6-address argument is the IPv6 address of the BGP-speaking neighbor.

                    Note   

                    This argument must be in the form documented in RFC 2373, where the address is specified in hexadecimal using 16-bit values between colons.

                    • The peer-group-name argument is the name of a BGP peer group.

                    • The interface-type argument is the interface type.

                    • The interface-number argument is the interface number.

                     
                    Step 9 address-family ipv4 [unicast] vrf vrf-name


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

                    Enters address family configuration mode for configuring routing protocols such as BGP, Routing Information Protocol (RIP), and static routing.

                    • The unicast keyword specifies unicast prefixes.

                    • The vrf vrf-name keyword and argument specify the name of a VPN routing/forwarding instance (VRF) to associate with submode commands.

                     
                    Step 10 neighbor {ip-address | peer-group-name | ipv6-address} activate


                    Example:
                    Device(config-router-af)# neighbor 10.20.20.20 activate
                     

                    Enables the exchange of information with a BGP neighbor.

                    • The ip-address argument is the IP address of the neighboring device.

                    • The peer-group-name argument is the name of the BGP peer group.

                    • The ipv6-address argument is the IPv6 address of the BGP-speaking neighbor.

                    Note   

                    This argument must be in the form documented in RFC 2373, where the address is specified in hexadecimal using 16-bit values between colons.

                     
                    Step 11 neighbor {ip-address | peer-group-name} send-community [both | standard | extended


                    Example:
                    Device(config-router-af)# neighbor 10.20.20.20 send-community extended
                     

                    Specifies that a communities attribute should be sent to a BGP neighbor.

                    • The ip-address argument is the IP address of the neighboring device.

                    • The peer-group-name argument is the name of the BGP peer group.

                    • The both keyword specifies that both standard and extended communities will be sent.

                    • The standard keyword specifies that only standard communities will be sent.

                    • The extended keyword specifies that only extended communities will be sent.

                     
                    Step 12 end


                    Example:
                    Device(config)# end
                     

                    Exits to privileged EXEC mode.

                     

                    Verifying That Load Sharing Occurs Between Loopbacks

                    To verify that load sharing can occur between loopbacks, ensure that the Multiprotocol Label Switching (MPLS) Label Forwarding Information Base (LFIB) entry for the neighbor route lists the available paths and interfaces.

                    SUMMARY STEPS

                      1.    enable

                      2.    show mpls forwarding-table [network {mask |length} | labels label [label] | interface interface | next-hop address | lsp-tunnel [tunnel-id]] [vrf vrf-name] [detail]

                      3.    disable


                    DETAILED STEPS
                       Command or ActionPurpose
                      Step 1 enable


                      Example:
                      Device> enable
                       

                      Enables privileged EXEC mode.

                      • Enter your password if prompted.

                       
                      Step 2 show mpls forwarding-table [network {mask |length} | labels label [label] | interface interface | next-hop address | lsp-tunnel [tunnel-id]] [vrf vrf-name] [detail]


                      Example:
                      Device# show mpls forwarding-table
                       

                      Displays the contents of the MPLS LFIB.

                      • Enter a keyword or argument, if desired.

                       
                      Step 3 disable


                      Example:
                      Device# disable
                       

                      Exits to user EXEC mode.

                       

                      Configuring Directly Connected Loopback Peering on MPLS VPN Carrier Supporting Carrier

                      The following sections explain how to load balance Carrier Supporting Carrier (CSC) traffic by peering loopback interfaces of directly connected CSC-provider edge (PE) and CSC-customer edge (CE) devices:

                      The figure below shows the loopback configuration for directly connected CSC-PE and CSC-CE devices. This configuration is used as the example in the tasks that follow.

                      Figure 3. Loopback Interface Configuration for Directly Connected CSC-PE and CSC-CE Devices

                      Configuring Loopback Interface Addresses on CSC-PE Devices


                      Note

                      Configuration of a loopback interface address on the Carrier Supporting Carrier (CSC)-provider edge (PE) device requires the enabling of a virtual routing and forwarding (VRF) instance. The CSC-customer edge (CE) device loopback interface does not require enabling a VRF.

                      SUMMARY STEPS

                        1.    enable

                        2.    configure terminal

                        3.    interface loopback interface number

                        4.    ip vrf forwarding vrf-name

                        5.    ip address ip-address mask [secondary]

                        6.    end


                      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 loopback interface number


                        Example:
                        Device(config)# interface loopback 0
                         

                        Configures a software-only virtual interface that emulates an interface that is always up, and enters interface configuration mode.

                        • The interface-number argument is the number of the loopback interface that you want to create or configure. There is no limit on the number of loopback interfaces that you can create.

                         
                        Step 4 ip vrf forwarding vrf-name


                        Example:
                        Device(config-if)# ip vrf forwarding vpn1
                         

                        Associates a VRF with the specified interface or subinterface.

                        • The vrf-name argument is the name assigned to a VRF.

                         
                        Step 5 ip address ip-address mask [secondary]


                        Example:
                        Device(config-if)# ip address 10.20.20.20 255.255.255.255
                         

                        Sets a primary or secondary IP address for an interface.

                        • The ip-address argument is the IP address.

                        • The mask argument is the mask for the associated IP subnet.

                        • The secondary keyword specifies that the configured address is a secondary IP address. If this keyword is omitted, the configured address is the primary IP address.

                         
                        Step 6 end


                        Example:
                        Device(config)# end
                         

                        Exits to privileged EXEC mode.

                         

                        Configuring Loopback Interface Addresses for CSC-CE Routers

                        SUMMARY STEPS

                          1.    enable

                          2.    configure terminal

                          3.    interface loopback interface-number

                          4.    ip address ip-address mask [secondary]

                          5.    end


                        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 loopback interface-number


                          Example:
                          Device(config)# interface loopback 0
                           

                          Configures a software-only virtual interface that emulates an interface that is always up.

                          • The interface-number argument is the number of the loopback interface that you want to create or configure. There is no limit on the number of loopback interfaces that you can create.

                           
                          Step 4 ip address ip-address mask [secondary]


                          Example:
                          Device(config-if)# ip address 10.10.10.10 255.255.255.255
                           

                          Sets a primary or secondary IP address for an interface.

                          • The ip-address argument is the IP address.

                          • The mask argument is the mask for the associated IP subnet.

                          • The secondary keyword specifies that the configured address is a secondary IP address. If this keyword is omitted, the configured address is the primary IP address.

                           
                          Step 5 end


                          Example:
                          Device(config-if)# end
                           

                          Exits to privileged EXEC mode.

                           

                          Configuring /32 Static Routes to the eBGP Neighbor Loopback on the CSC-PE Device

                          SUMMARY STEPS

                            1.    enable

                            2.    configure terminal

                            3.    ip route vrf vrf-name prefix mask {ip-address | interface-type interface-number [ip-address]} [global] [distance] [name] [permanent] [tag tag]

                            4.    end


                          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 ip route vrf vrf-name prefix mask {ip-address | interface-type interface-number [ip-address]} [global] [distance] [name] [permanent] [tag tag]


                            Example:
                            Device(config)# ip route vrf vpn1 10.10.10.10 255.255.255.255 Ethernet 1/0 172.16.0.2
                             

                            Establishes static routes for a virtual routing and forwarding (VRF) instance.

                            • The vrf-name argument is the name of the VRF for the static route.

                            • The prefix argument is the IP route prefix for the destination.

                            • The mask argument is the prefix mask for the destination.

                            • The ip-address argument is the IP address of the next hop that you can use to reach the destination network.

                            • The interface-type and interface-number arguments are the network interface type and interface number.

                            • The global keyword specifies that the given next hop address is in the nonVRF routing table.

                            • The distance argument is an administrative distance.

                            • The name argument applies a name to the specified route.

                            • The permanent keyword specifies that the route is not to be removed, even if the interface shuts down.

                            • The tag tag keyword and argument name a tag value that can be used as a “match” value for controlling redistribution via route maps.

                             
                            Step 4 end


                            Example:
                            Device(config)# end
                             

                            Exits to privileged EXEC mode.

                             

                            Configuring /32 Static Routes to the eBGP Neighbor Loopback on the CSC-CE Device

                            SUMMARY STEPS

                              1.    enable

                              2.    configure terminal

                              3.    ip route prefix mask {ip-address | interface-type interface-number [ip-address]} [distance] [name] [permanent] [tag tag]

                              4.    end


                            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 ip route prefix mask {ip-address | interface-type interface-number [ip-address]} [distance] [name] [permanent] [tag tag]


                              Example:
                              Device(config)# ip route 10.20.20.20 255.255.255.255 Ethernet 1/0 172.16.0.1
                               

                              Establishes static routes.

                              • The prefix argument is the IP route prefix for the destination.

                              • The mask argument is the prefix mask for the destination.

                              • The ip-address argument is the IP address of the next hop that you can use to reach the destination network.

                              • The interface-type and interface-number arguments are the network interface type and interface number.

                              • The distance argument is an administrative distance.

                              • The name argument applies a name to the specified route.

                              • The permanent keyword specifies that the route is not to be removed, even if the interface shuts down.

                              • The tag tag keyword and argument name a tag value that can be used as a “match” value for controlling redistribution via route maps.

                               
                              Step 4 end


                              Example:
                              Device(config)# end
                               

                              Exits to privileged EXEC mode.

                               

                              Configuring Forwarding on CSC-PE Interfaces That Connect to the CSC-CE Loopback

                              SUMMARY STEPS

                                1.    enable

                                2.    configure terminal

                                3.    interface type slot/port

                                4.    ip vrf forwarding vrf-name

                                5.    ip address ip-address mask [secondary]

                                6.    mpls bgp forwarding

                                7.    exit

                                8.    Repeat Steps 3 through 6 for another connecting interface (Ethernet 0/0).

                                9.    end


                              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 slot/port


                                Example:
                                Device(config)# interface ethernet 1/0
                                 

                                Configures an interface type and enters interface configuration mode.

                                • The type argument is the type of interface to be configured.

                                • The slot argument is the slot number. Refer to the appropriate hardware manual for slot and port information.

                                • The /port argument is the port number. Refer to the appropriate hardware manual for slot and port information.

                                 
                                Step 4 ip vrf forwarding vrf-name


                                Example:
                                Device(config-if)# ip vrf forwarding vpn1
                                 

                                Associates a virtual routing and forwarding (VRF) instance with an interface or subinterface.

                                • The vrf-name argument is the name assigned to a VRF.

                                 
                                Step 5 ip address ip-address mask [secondary]


                                Example:
                                Device(config-if)# ip address 172.16.0.1 255.255.255.255
                                 

                                Sets a primary or secondary IP address for an interface.

                                • The ip-address argument is the IP address.

                                • The mask argument is the mask for the associated IP subnet.

                                • The secondary keyword specifies that the configured address is a secondary IP address. If this keyword is omitted, the configured address is the primary IP address.

                                 
                                Step 6 mpls bgp forwarding


                                Example:
                                Device(config-if)# mpls bgp forwarding
                                 

                                Configures the Border Gateway Protocol (BGP) to enable Multiprotocol Label Switching (MPLS) forwarding on connecting interfaces.

                                 
                                Step 7 exit


                                Example:
                                Device(config-if)# exit
                                 

                                Exits to global configuration mode.

                                 
                                Step 8 Repeat Steps 3 through 6 for another connecting interface (Ethernet 0/0).    
                                Step 9 end


                                Example:
                                Device(config)# end
                                 

                                Exits to privileged EXEC mode.

                                 

                                Configuring Forwarding on CSC-CE Interfaces That Connect to the CSC-PE Loopback

                                SUMMARY STEPS

                                  1.    enable

                                  2.    configure terminal

                                  3.    interface typeslot/port

                                  4.    mpls bgp forwarding

                                  5.    exit

                                  6.    Repeat Steps 3 and 4 for another connecting interface (Ethernet 0/0).

                                  7.    end


                                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 typeslot/port


                                  Example:
                                  Device(config)# interface ethernet 1/0
                                   

                                  Configures an interface type and enters interface configuration mode.

                                  • The type argument is the type of interface to be configured.

                                  • The slot argument is the slot number. Refer to the appropriate hardware manual for slot and port information.

                                  • The /port argument is the port number. Refer to the appropriate hardware manual for slot and port information.

                                   
                                  Step 4 mpls bgp forwarding


                                  Example:
                                  Device(config-if)# mpls bgp forwarding
                                   

                                  Configures the Border Gateway Protocol (BGP) to enable Multiprotocol Label Switching (MPLS) forwarding on connecting interfaces.

                                   
                                  Step 5 exit


                                  Example:
                                  Device(config-if)# exit
                                   

                                  Exits to global configuration mode.

                                   
                                  Step 6 Repeat Steps 3 and 4 for another connecting interface (Ethernet 0/0).    
                                  Step 7 end


                                  Example:
                                  Device(config)# end
                                   

                                  Exits to privileged EXEC mode.

                                   

                                  Configuring an eBGP Session Between the CSC-PE Device and the CSC-CE Loopback

                                  SUMMARY STEPS

                                    1.    enable

                                    2.    configure terminal

                                    3.    router bgp as-number

                                    4.    bgp log-neighbor-changes

                                    5.    neighbor {ip-address | peer-group-name} remote-as as-number

                                    6.    neighbor {ip-address | peer-group-name} disable-connected-check

                                    7.    neighbor {ip-address | ipv6-address | peer-group-name} update-source interface-type interface-number

                                    8.    address-family ipv4 [unicast] vrf vrf-name

                                    9.    ip vrf forwarding vrf-name

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

                                    11.    neighbor ip-address send-label

                                    12.    end


                                  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 200
                                     

                                    Configures the Border Gateway Protocol (BGP) routing process.

                                    • The as-number argument indicates the number of an autonomous system that identifies the device to other BGP routers and tags the routing information passed along.

                                     
                                    Step 4 bgp log-neighbor-changes


                                    Example:
                                    Device(config-router)# bgp log-neighbor-changes
                                     

                                    Enables logging of BGP neighbor resets.

                                     
                                    Step 5 neighbor {ip-address | peer-group-name} remote-as as-number


                                    Example:
                                    Device(config-router)# neighbor 10.10.10.10 remote-as 100
                                     

                                    Adds an entry to the BGP or multiprotocol BGP neighbor table.

                                    • The ip-address argument is the IP address of the neighbor.

                                    • The peer-group-name argument is the name of a BGP peer group.

                                    • The as-number argument is the autonomous system to which the neighbor belongs.

                                     
                                    Step 6 neighbor {ip-address | peer-group-name} disable-connected-check


                                    Example:
                                    Device(config-router)# neighbor 10.10.10.10 disable-connected-check
                                     

                                    Allows peering between loopbacks.

                                    • The ip-addressargument is the IP address of the neighbor.

                                    • The peer-group-name argument is the name of a BGP peer group.

                                     
                                    Step 7 neighbor {ip-address | ipv6-address | peer-group-name} update-source interface-type interface-number


                                    Example:
                                    Device(config-router)# neighbor 10.10.10.10 update-source Loopback 0
                                     

                                    Allows BGP sessions to use any operational interface for TCP connections.

                                    • The ip-address argument is the IPv4 address of the BGP-speaking neighbor.

                                    • The ipv6-address argument is the IPv6 address of the BGP-speaking neighbor.

                                    This argument must be in the form documented in RFC 2373, where the address is specified in hexadecimal using 16-bit values between colons.

                                    • The peer-group-name argument is the name of a BGP peer group.

                                    • The interface-type argument is the interface type.

                                    • The interface-number argument is the interface number.

                                     
                                    Step 8 address-family ipv4 [unicast] vrf vrf-name


                                    Example:
                                    Device(config-router)# address-family ipv4 vrf vpn1
                                     

                                    Enters address family configuration mode for configuring routing protocols such as BGP, Routing Information Protocol (RIP), and static routing.

                                    • The ipv4 keyword configures sessions that carry standard IPv4 address prefixes.

                                    • The unicast keyword specifies unicast prefixes.

                                    • The vrf vrf-name keyword and argument specify the name of a virtual routing and forwarding (VRF) instance to associate with submode commands.

                                     
                                    Step 9 ip vrf forwarding vrf-name


                                    Example:
                                    Device(config-router-af)# ip vrf forwarding vpn1
                                     

                                    Associates a VRF with an interface or subinterface.

                                    • The vrf-name argument is the name assigned to a VRF.

                                     
                                    Step 10 neighbor {ip-address | peer-group-name | ipv6-address} activate


                                    Example:
                                    Device(config-router-af)# neighbor 10.10.10.10 activate
                                     

                                    Enables the exchange of information with a BGP neighbor.

                                    • The ip-address argument is the IP address of the neighboring device.

                                    • The peer-group-name argument is the name of the BGP peer group.

                                    • The ipv6-address argument is the IPv6 address of the BGP-speaking neighbor.

                                    Note   

                                    This argument must be in the form documented in RFC 2373, where the address is specified in hexadecimal using 16-bit values between colons.

                                     
                                    Step 11 neighbor ip-address send-label


                                    Example:
                                    Device(config-router-af)# neighbor 10.10.10.10 send-label
                                     

                                    Enables a BGP device to send MPLS labels with BGP routes to a neighboring BGP device.

                                    • The ip-address argument is the IP address of the neighboring device.

                                     
                                    Step 12 end


                                    Example:
                                    Device(config)# end
                                     

                                    Exits to privileged EXEC mode.

                                     

                                    Configuring an eBGP Session Between the CSC-CE Device and the CSC-PE Loopback

                                    SUMMARY STEPS

                                      1.    enable

                                      2.    configure terminal

                                      3.    router bgp as-number

                                      4.    bgp log-neighbor-changes

                                      5.    neighbor {ip-address | peer-group-name} remote-as as-number

                                      6.    neighbor {ip-address | peer-group-name} disable-connected-check

                                      7.    neighbor {ip-address | ipv6-address | peer-group-name} update-source interface-type interface-number

                                      8.    address-family ipv4 [unicast] [vrf vrf-name]

                                      9.    neighbor {ip-address | peer-group-name|ipv6-address] activate

                                      10.    neighbor ip-address send-label

                                      11.    end


                                    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 200
                                       

                                      Configures the Border Gateway Protocol (BGP) routing process.

                                      • The as-number argument indicates the number of an autonomous system that identifies the device to other BGP routers and tags the routing information passed along.

                                       
                                      Step 4 bgp log-neighbor-changes


                                      Example:
                                      Device(config-router)# bgp log-neighbor-changes
                                       

                                      Enables logging of BGP neighbor resets.

                                       
                                      Step 5 neighbor {ip-address | peer-group-name} remote-as as-number


                                      Example:
                                      Device(config-router)# neighbor 10.20.20.20 remote-as 100
                                       

                                      Adds an entry to the BGP or multiprotocol BGP neighbor table.

                                      • The ip-address argument is the IP address of the neighbor.

                                      • The peer-group-name argument is the name of a BGP peer group.

                                      • The as-number argument is the autonomous system to which the neighbor belongs.

                                       
                                      Step 6 neighbor {ip-address | peer-group-name} disable-connected-check


                                      Example:
                                      Device(config-router)# neighbor 10.20.20.20 disable-connected-check
                                       

                                      Allows peering between loopbacks.

                                      • The ip-address argument is the IP address of the neighbor.

                                      • The peer-group-name argument is the name of a BGP peer group.

                                       
                                      Step 7 neighbor {ip-address | ipv6-address | peer-group-name} update-source interface-type interface-number


                                      Example:
                                      Device(config-router)# neighbor 10.20.20.20 update-source Loopback 0
                                       

                                      Allows BGP sessions to use any operational interface for TCP connections.

                                      • The ip-address argument is the IPv4 address of the BGP-speaking neighbor.

                                      • The ipv6-address argument is the IPv6 address of the BGP-speaking neighbor.

                                      This argument must be in the form documented in RFC 2373, where the address is specified in hexadecimal using 16-bit values between colons.

                                      • The peer-group-name argument is the name of a BGP peer group.

                                      • The interface-type argument is the interface type.

                                      • The interface-number argument is the interface number.

                                       
                                      Step 8 address-family ipv4 [unicast] [vrf vrf-name]


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

                                      Enters address family configuration mode for configuring routing protocols such as BGP, RIP, and static routing.

                                      • The ipv4 keyword configures sessions that carry standard IPv4 address prefixes.

                                      • The unicast keyword specifies unicast prefixes.

                                      • The vrf vrf-name keyword and argument specify the name of a virtual routing and forwarding (VRF) instance to associate with submode commands.

                                       
                                      Step 9 neighbor {ip-address | peer-group-name|ipv6-address] activate


                                      Example:
                                      Device(config-router-af)# neighbor 10.20.20.20 activate
                                       

                                      Enables the exchange of information with a BGP neighbor.

                                      • The ip-address argument is the IP address of the neighboring device.

                                      • The peer-group-name argument is the name of the BGP peer group.

                                      • The ipv6-address argument is the IPv6 address of the BGP-speaking neighbor.

                                      Note   

                                      This argument must be in the form documented in RFC 2373, where the address is specified in hexadecimal using 16-bit values between colons.

                                       
                                      Step 10 neighbor ip-address send-label


                                      Example:
                                      Device(config-router-af)# neighbor 10.20.20.20 send-label
                                       

                                      Enables a BGP device to send Multiprotocol Label Switching (MPLS) labels with BGP routes to a neighboring BGP device.

                                      • The ip-address argument is the IP address of the neighboring device.

                                       
                                      Step 11 end


                                      Example:
                                      Device(config)# end
                                       

                                      Exits to privileged EXEC mode.

                                       

                                      Verifying That Load Sharing Occurs Between Loopbacks

                                      To verify that load sharing occurs between loopbacks, ensure that the Multiprotocol Label Switching (MPLS) Label Forwarding Information Base (LFIB) entry for the neighbor route lists the available paths and interfaces.

                                      SUMMARY STEPS

                                        1.    enable

                                        2.    show mpls forwarding-table [vrf vrf-name] [{network {mask | length} | labels label [-label] | [ interface] interface | next-hop address | lsp-tunnel [tunnel-id]}] [detail]

                                        3.    disable


                                      DETAILED STEPS
                                         Command or ActionPurpose
                                        Step 1 enable


                                        Example:
                                        Device> enable
                                         

                                        Enables privileged EXEC mode.

                                        • Enter your password if prompted.

                                         
                                        Step 2 show mpls forwarding-table [vrf vrf-name] [{network {mask | length} | labels label [-label] | [ interface] interface | next-hop address | lsp-tunnel [tunnel-id]}] [detail]


                                        Example:
                                        Device# show mpls forwarding-table
                                         

                                        Displays the contents of the MPLS LFIB.

                                         
                                        Step 3 disable


                                        Example:
                                        Device# disable
                                         

                                        Exits to user EXEC mode.

                                         

                                        Configuration Examples for MPLS VPN Load Balancing Support for Inter-AS and CSC VPN

                                        Examples: Configuring a 32 Static Route from an ASBR to the Loopback Address of Another ASBR

                                        The following example configures a /32 static route from ASBR1 to the loopback address of ASBR2: 

                                        Device# configure terminal
Device(config)# ip route 10.20.20.20 255.255.255 e1/0 168.192.0.1
Device(config)# ip route 10.20.20.20 255.255.255 e0/0 168.192.2.1

                                        The following example configures a /32 static route from ASBR2 to the loopback address of ASBR1: 

                                        Device# configure terminal
Device(config)# ip route vrf vpn1 10.10.10.10 255.255.255 e1/0 168.192.0.2
Device(config)# ip route vrf vpn1 10.10.10.10 255.255.255 e0/0 168.192.2.2

                                        Example: Configuring BGP MPLS Forwarding on the Interfaces Connecting ASBRs

                                        The following example configures the Border Gateway Protocol (BGP) and Multiprotocol Label Switching (MPLS) forwarding on the interfaces connecting ASBR2 with ASBR1: 

                                        Device# configure terminal
Device(config)# interface ethernet 1/0
Device(config-if)# ip vrf forwarding vpn1
Device(config-if)# ip address 168.192.0.1 255.255.255.255
Device(config-if)# mpls bgp forwarding
Device(config-if)# exit
Device(config)# interface ethernet 0/0
Device(config-if)# ip vrf forwarding vpn1
Device(config-if)# ip address 168.192.2.1 255.255.255.255
Device(config-if)# mpls bgp forwarding
Device(config-if)# exit

                                        Example: Configuring VPNv4 Sessions on an ASBR

                                        The following example configures VPNv4 sessions on ASBR2: 

                                        Device# configure terminal
Device(config)# router bgp 200
Device(config-router)# bgp log-neighbor-changes
Device(config-router)# neighbor 10.10.10.10 remote-as 100
Device(config-router)# neighbor 10.10.10.10 disable-connected-check
Device(config-router)# neighbor bb.bb.bb.bb ebgp-multihop 255
Device(config-router)# neighbor 10.10.10.10 update-source Loopback0
!
Device(config-router)# address-family vpnv4
Device(config-router-af)# neighbor 10.10.10.10 activate
Device(config-router-af)# neighbor 10.10.10.10 send-community extended
Device(config-router-af)# end

                                        Additional References

                                        Related Documents

                                        Related Topic

                                        Document Title

                                        Cisco IOS commands

                                        Cisco IOS Master Command List, All Releases

                                        MPLS commands

                                        Cisco IOS Multiprotocol Label Switching Command Reference

                                        Configuring MPLS VPN CSC with BGP

                                        “MPLS VPN Carrier Supporting Carrier with BGP” module in the MPLS: Layer 3 VPNs: Inter-AS and CSC Configuration Guide

                                        Configuring BGP

                                        “Configuring BGP” module in the IP Routing: BGP Configuration Guide

                                        Configuring BGP Multipath Load Sharing for Both eBGP and iBGP in an MPLS VPN

                                        “BGP Multipath Load Sharing for Both eBGP and iBGP in an MPLS VPN” module in the IP Routing: BGP Configuration Guide

                                        RFCs

                                        RFC

                                        Title

                                        RFC 1164

                                        Application of the Border Gateway Protocol in the Internet

                                        RFC 1171

                                        A Border Gateway Protocol 4

                                        RFC 1700

                                        Assigned Numbers

                                        RFC 1966

                                        BGP Route Reflection: An Alternative to Full Mesh IBGP

                                        RFC 2283

                                        Multiprotocol Extensions for BGP-4

                                        RFC 2373

                                        IP Version 6 Addressing Architecture

                                        RFC 2547

                                        BGP/MPLS VPNs

                                        RFC 2842

                                        Capabilities Advertisement with BGP-4

                                        RFC 2858

                                        Multiprotocol Extensions for BGP-4

                                        RFC 3107

                                        Carrying Label Information in BGP-4

                                        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 MPLS VPN Load Balancing Support for Inter-AS and CSC VPN

                                        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 MPLS VPN Load Balancing Support for Inter-AS and CSC VPN

                                        Feature Name

                                        Releases

                                        Feature Information

                                        MPLS VPN Load Balancing Support for Inter-AS and CSC VPNs

                                        12.0(29)S

                                        12.4(20)T

                                        12.2(33)SRA

                                        12.2(33)SXH

                                        Cisco IOS XE Release 2.2

                                        The MPLS VPN Load Balancing Support for Inter-AS and CSC VPNs feature allows MPLS VPN Inter-AS and MPLS VPN CSC networks to load share traffic between adjacent LSRs that are connected by multiple links. The LSRs can be a pair of ASBRs or a CSC-PE and a CSC-CE. Using directly connected loopback peering allows load sharing at the IGP level, so more than one BGP session is not needed between the LSRs. No other label distribution mechanism is needed between the adjacent LSRs than BGP.

                                        In Cisco IOS Release 12.0(29)S, this feature was introduced.

                                        In Cisco IOS Release 12.4(20)T, 12.2(33)SRA, and 12.2(33)SXH, this feature was integrated.

                                        In Cisco IOS XE Release 2.2, this feature was implemented on the Cisco ASR 1000 Series Routers.

                                        No commands were introduced or modified.