L2VPN Pseudowire Switching

This feature module explains how to configure L2VPN Pseudowire Switching, which extends layer 2 virtual private network (L2VPN) pseudowires across an interautonomous system (inter-AS) boundary or across two separate multiprotocol label switching (MPLS) networks.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/​go/​cfn. An account on Cisco.com is not required.

Restrictions for L2VPN Pseudowire Switching

  • In Cisco IOS XE Release 2.4, Pseudowire Switching is supported on Ethernet over MPLS attachment circuits.

  • L2VPN Pseudowire Switching is supported with AToM.

  • Only static, on-box provisioning is supported.

  • Sequencing numbers in AToM packets are not processed by L2VPN Pseudowire Switching. The feature blindly passes the sequencing data through the xconnect packet paths, a process that is called transparent sequencing. The endpoint PE-CE connections enforce the sequencing.

  • You can ping the adjacent next-hop PE router. End-to-end LSP pings are not supported.

  • Do not configure IP or Ethernet interworking on a router where L2VPN Pseudowire Switching is enabled. Instead, configure interworking on the routers at the edge PEs of the network.

  • The control word negotiation results must match. If either segment does not negotiate the control word, the control word is disabled for both segments.

  • AToM Graceful Restart is negotiated independently on each pseudowire segment. If there is a transient loss of the LDP session between two AToM PE routers, packets continue to flow.

  • Per-pseudowire quality of service (QoS) is not supported. Traffic Engineering (TE) tunnel selection is supported.

  • Attachment circuit interworking is not supported.

Information About L2VPN Pseudowire Switching

How L2VPN Pseudowire Switching Works

L2VPN Pseudowire Switching allows the user to extend L2VPN pseudowires across an inter-AS boundary or across two separate MPLS networks, as shown in the figures below. L2VPN Pseudowire Switching connects two or more contiguous pseudowire segments to form an end-to-end multihop pseudowire. This end-to-end pseudowire functions as a single point-to-point pseudowire.

As shown in the second figure below, L2VPN Pseudowire Switching enables you to keep the IP addresses of the edge PE routers private across inter-AS boundaries. You can use the IP address of the autonomous system boundary routers (ASBRs) and treat them as pseudowire aggregation (PE-agg) routers. The ASBRs join the pseudowires of the two domains.

L2VPN Pseudowire Switching also enables you to keep different administrative or provisioning domains to manage the end-to-end service. At the boundaries of these networks, PE-agg routers delineate the management responsibilities.

Figure 1. L2VPN Pseudowire Switching in an Intra-AS Topology

Figure 2. L2VPN Pseudowire Switching in an Inter-AS Topology

How Packets Are Manipulated at the Aggregation Point

Switching AToM packets between two AToM pseudowires is the same as switching any MPLS packet. The MPLS switching data path switches AToM packets between two AToM pseudowires. The following list explains exceptions:

  • The outgoing virtual circuit (VC) label replaces the incoming VC label in the packet. New Internal Gateway Protocol (IGP) labels and Layer 2 encapsulation are added.

  • The incoming VC label time-to-live (TTL) field is decremented by one and copied to the outgoing VC label TTL field.

  • The incoming VC label EXP value is copied to the outgoing VC label EXP field.

  • The outgoing VC label ‘Bottom of Stack’ S bit in the outgoing VC label is set to1.

  • AToM control word processing is not performed at the L2VPN Pseudowire Switching aggregation point. Sequence numbers are not validated. Use the Router Alert label for LSP Ping; do not require control word inspection to determine an LSP Ping packet.

How to Configure L2VPN Pseudowire Switching

Configuring

Use the following procedure to configure L2VPN Pseudowire Switching on each of the PE-agg routers.

Before You Begin

  • This procedure assumes that you have configured basic AToM L2VPNs. This procedure does not explain how to configure basic AToM L2VPNs that transport Layer 2 packets over an MPLS backbone. For information on the basic configuration, see Any Transport over MPLS.

  • For inter-Autonomous configurations, ASBRs require a labeled interface.


Note

In this configuration, you are limited to two neighborcommands after entering the l2 vficommand.

>

SUMMARY STEPS

    1.    enable

    2.    configure terminal

    3.    l2 vfi name point-to-point

    4.    neighbor ip-address vcid encapsulation mpls | pw-class pw-class-name

    5.    exit

    6.    exit

    7.    show mpls l2transport vc [vcid [vc-id | [vc-id-min vc-id-max]] [interface name[local-circuit-id]] [destination ip-address | name] [detail]

    8.    show vfi [vfi-name]

    9.    ping [protocol] [tag] {host-name| system-address}


DETAILED STEPS
     Command or ActionPurpose
    Step 1 enable


    Example:
    Router> enable
     

    Enables privileged EXEC mode.

    • Enter your password if prompted.

     
    Step 2 configure terminal


    Example:
    Router# configure terminal
     

    Enters global configuration mode.

     
    Step 3 l2 vfi name point-to-point


    Example:
    Router(config)# l2 vfi atomtunnel point-to-point
     

    Creates a point-to-point Layer 2 virtual forwarding interface (VFI) and enters VFI configuration mode.

     
    Step 4 neighbor ip-address vcid encapsulation mpls | pw-class pw-class-name


    Example:
    Router(config-vfi)# neighbor 10.0.0.1 100 pw-class mpls
     

    Sets up an emulated VC. Specify the IP address and the VC ID of the remote router. Also specify the pseudowire class to use for the emulated VC.

    Note   

    Only two neighborcommands are allowed for each l2 vfi point-to-point command.

     
    Step 5 exit


    Example:
    Router(config-vfi)# exit
     

    Exits VFI configuration mode.

     
    Step 6 exit


    Example:
    Router(config)# exit
     

    Exits global configuration mode.

     
    Step 7 show mpls l2transport vc [vcid [vc-id | [vc-id-min vc-id-max]] [interface name[local-circuit-id]] [destination ip-address | name] [detail]


    Example:
    Router# show mpls l2transport vc
     

    Verifies that the L2VPN Pseudowire Switching session has been established.

     
    Step 8 show vfi [vfi-name]


    Example:
    Router# show vfi atomtunnel
     

    Verifies that a point-to-point VFI has been established.

     
    Step 9 ping [protocol] [tag] {host-name| system-address}


    Example:
    Router# ping 10.1.1.1
     

    When issued from the CE routers, this command verifies end-to-end connectivity.

     

    Examples

    The following example displays the output of the show mpls l2transport vc command: 

    Router# show mpls l2transport vc
Local intf     Local circuit              Dest address    VC ID Status   
-------------  -------------------------- --------------- ----- ---- 
MPLS PW        10.0.1.1:100               10.0.1.1        100   UP 
MPLS PW        10.0.1.1:100               10.0.1.1        100   UP

    The following example displays the output of the show vficommand: 

    Router# show vfi
VFI name: test, type: point-to-point
 Neighbors connected via pseudowires:
   Router ID        Pseudowire ID
   10.0.1.1         100      
   10.0.1.1         100

    How to Configure L2VPN Pseudowire Switching using the commands associated with the L2VPN Protocol-Based CLIs feature

    Perform this task to configure L2VPN Pseudowire Switching on each of the PE-agg routers. In this configuration, you are limited to two neighbor commands after entering the l2vpn xconnect command.

    Before You Begin

    • This task assumes that you have configured basic AToM L2VPNs. This task does not explain how to configure basic AToM L2VPNs that transport Layer 2 packets over an MPLS backbone. For information on the basic configuration, see the “Any Transport over MPLS” section.

    • For interautonomous configurations, autonomous system boundary routers (ASBRs) require a labeled interface.

    SUMMARY STEPS

      1.    enable

      2.    configure terminal

      3.    interface pseudowire number

      4.    encapsulation mpls

      5.    neighbor peer-address vcid-value

      6.    exit

      7.    interface pseudowire number

      8.    encapsulation mpls

      9.    neighbor peer-address vcid-value

      10.    exit

      11.    l2vpn xconnect context context-name

      12.    member pseudowire interface-number

      13.    member ip-address vcid encapsulation mpls

      14.    member pseudowire interface-number

      15.    member ip-address vcid encapsulation mpls

      16.    exit

      17.    exit

      18.    show l2vpn atom vc [vcid [vc-id | vc-id-min vc-id-max]] [interface type number [local-circuit-id]] [destination ip-address | name] [detail]

      19.    ping [protocol] [tag] {hostname| system-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 interface pseudowire number


      Example:
      Router(config)# interface pseudowire 100
       

      Specifies the pseudowire interface and enters interface configuration mode.

       
      Step 4 encapsulation mpls


      Example:
      Router(config-if)# encapsulation mpls
       

      Specifies that Multiprotocol Label Switching (MPLS) is used as the data encapsulation method.

       
      Step 5 neighbor peer-address vcid-value


      Example:
      Router(config-if)# neighbor 10.0.0.1 123
       

      Specifies the peer IP address and virtual circuit (VC) ID value of the Layer 2 VPN (L2VPN) pseudowire.

       
      Step 6 exit


      Example:
      Router(config-if)# exit
       

      Exits interface configuration mode.

       
      Step 7 interface pseudowire number


      Example:
      Router(config)# interface pseudowire 200
       

      Specifies the pseudowire interface and enters interface configuration mode.

       
      Step 8 encapsulation mpls


      Example:
      Router(config-if)# encapsulation mpls
       

      Specifies that Multiprotocol Label Switching (MPLS) is used as the data encapsulation method.

       
      Step 9 neighbor peer-address vcid-value


      Example:
      Router(config-if)# neighbor 10.0.0.2 124
       

      Specifies the peer IP address and virtual circuit (VC) ID value of the Layer 2 VPN (L2VPN) pseudowire.

       
      Step 10 exit


      Example:
      Router(config-if)# exit
       

      Exits interface configuration mode.

       
      Step 11 l2vpn xconnect context context-name


      Example:
      Device(config)# l2vpn xconnect context con1
       

      Creates a Layer 2 VPN (L2VPN) cross connect context and enters xconnect configuration mode.

       
      Step 12 member pseudowire interface-number


      Example:
      Router(config-xconnect)# member pseudowire 100
       

      Specifies a member pseudowire to form a Layer 2 VPN (L2VPN) cross connect.

       
      Step 13 member ip-address vcid encapsulation mpls


      Example:
      Device(config-xconnect)# member 10.0.0.1 123 encapsulation mpls
       

      Specifies the devices that form a point-to-point Layer 2 VPN (L2VPN) virtual forwarding interface (VFI) connection.

      Note   

      Only two member commands are allowed for each l2vpn xconnect context command.

       
      Step 14 member pseudowire interface-number


      Example:
      Router(config-xconnect)# member pseudowire 200
       

      Specifies a member pseudowire to form a Layer 2 VPN (L2VPN) cross connect.

       
      Step 15 member ip-address vcid encapsulation mpls


      Example:
      Device(config-xconnect)# member 10.0.0.2 124 encapsulation mpls
       

      Specifies the devices that form a point-to-point Layer 2 VPN (L2VPN) virtual forwarding interface (VFI) connection.

      Note   

      Only two member commands are allowed for each l2vpn xconnect context command.

       
      Step 16 exit


      Example:
      Device(config-xconnect)# exit
       

      Exits Xconnect configuration mode.

       
      Step 17 exit


      Example:
      Device(config)# exit
       

      Exits global configuration mode.

       
      Step 18 show l2vpn atom vc [vcid [vc-id | vc-id-min vc-id-max]] [interface type number [local-circuit-id]] [destination ip-address | name] [detail]


      Example:
      Device# show l2vpn atom vc
       

      Displays information about Any Transport over MPLS (AToM) virtual circuits (VCs) and static pseudowires that have been enabled to route Layer 2 packets on a device.

       
      Step 19 ping [protocol] [tag] {hostname| system-address}


      Example:
      Device# ping 10.1.1.1
       

      When issued from the CE routers, verifies end-to-end connectivity.

       

      Configuring

      Use the following procedure to configure L2VPN Pseudowire Switching on each of the PE-agg routers.

      Before You Begin

      • This procedure assumes that you have configured basic AToM L2VPNs. This procedure does not explain how to configure basic AToM L2VPNs that transport Layer 2 packets over an MPLS backbone. For information on the basic configuration, see Any Transport over MPLS.

      • For inter-Autonomous configurations, ASBRs require a labeled interface.


      Note

      In this configuration, you are limited to two neighborcommands after entering the l2 vficommand.

      >

      SUMMARY STEPS

        1.    enable

        2.    configure terminal

        3.    l2 vfi name point-to-point

        4.    neighbor ip-address vcid encapsulation mpls | pw-class pw-class-name

        5.    exit

        6.    exit

        7.    show mpls l2transport vc [vcid [vc-id | [vc-id-min vc-id-max]] [interface name[local-circuit-id]] [destination ip-address | name] [detail]

        8.    show vfi [vfi-name]

        9.    ping [protocol] [tag] {host-name| system-address}


      DETAILED STEPS
         Command or ActionPurpose
        Step 1 enable


        Example:
        Router> enable
         

        Enables privileged EXEC mode.

        • Enter your password if prompted.

         
        Step 2 configure terminal


        Example:
        Router# configure terminal
         

        Enters global configuration mode.

         
        Step 3 l2 vfi name point-to-point


        Example:
        Router(config)# l2 vfi atomtunnel point-to-point
         

        Creates a point-to-point Layer 2 virtual forwarding interface (VFI) and enters VFI configuration mode.

         
        Step 4 neighbor ip-address vcid encapsulation mpls | pw-class pw-class-name


        Example:
        Router(config-vfi)# neighbor 10.0.0.1 100 pw-class mpls
         

        Sets up an emulated VC. Specify the IP address and the VC ID of the remote router. Also specify the pseudowire class to use for the emulated VC.

        Note   

        Only two neighborcommands are allowed for each l2 vfi point-to-point command.

         
        Step 5 exit


        Example:
        Router(config-vfi)# exit
         

        Exits VFI configuration mode.

         
        Step 6 exit


        Example:
        Router(config)# exit
         

        Exits global configuration mode.

         
        Step 7 show mpls l2transport vc [vcid [vc-id | [vc-id-min vc-id-max]] [interface name[local-circuit-id]] [destination ip-address | name] [detail]


        Example:
        Router# show mpls l2transport vc
         

        Verifies that the L2VPN Pseudowire Switching session has been established.

         
        Step 8 show vfi [vfi-name]


        Example:
        Router# show vfi atomtunnel
         

        Verifies that a point-to-point VFI has been established.

         
        Step 9 ping [protocol] [tag] {host-name| system-address}


        Example:
        Router# ping 10.1.1.1
         

        When issued from the CE routers, this command verifies end-to-end connectivity.

         

        Examples

        The following example displays the output of the show mpls l2transport vc command: 

        Router# show mpls l2transport vc
Local intf     Local circuit              Dest address    VC ID Status   
-------------  -------------------------- --------------- ----- ---- 
MPLS PW        10.0.1.1:100               10.0.1.1        100   UP 
MPLS PW        10.0.1.1:100               10.0.1.1        100   UP

        The following example displays the output of the show vficommand: 

        Router# show vfi
VFI name: test, type: point-to-point
 Neighbors connected via pseudowires:
   Router ID        Pseudowire ID
   10.0.1.1         100      
   10.0.1.1         100

        Configuration Examples for L2VPN Pseudowire Switching

        L2VPN Pseudowire Switching in an Inter-AS Configuration Example

        Two separate autonomous systems are able to pass L2VPN packets, because the two PE-agg routers have been configured with L2VPN Pseudowire Switching. This example configuration is shown in the figure below.

        Figure 3. L2VPN Pseudowire Switching in an InterAutonomous System

        CE1

        CE2 

        version 12.0
        service timestamps debug uptime
        service timestamps log uptime
        service password-encryption
        !
        hostname [ce1]
        !
        boot-start-marker
        boot-end-marker
        !
        enable secret 5 $1$o9N6$LSrxHufTn0vjCY0nW8hQX.
        !
        ip subnet-zero
        ip cef
        no ip domain-lookup
        !
        interface FastEthernet0/0/0
         ip address 10.0.0.1 255.255.255.252
         no ip directed-broadcast
        !
        ip classless
        !
        control-plane
        !
        line con 0
         exec-timeout 0 0
        line aux 0
        line vty 0 4
         login
        !
        no cns aaa enable
        end
        		 
        version 12.0
        service timestamps debug uptime
        service timestamps log uptime
        service password-encryption
        !
        hostname [ce2]
        !
        boot-start-marker
        boot-end-marker
        !
        enable secret 5 $1$YHo6$LQ4z5PdrF5B9dnL75Xvvm1
        !
        ip subnet-zero
        ip cef
        no ip domain-lookup
        !
        interface FastEthernet0/0/0
         ip address 10.0.0.2 255.255.255.252
         no ip directed-broadcast
        !
        ip classless
        !
        control-plane
        !
        line con 0
         exec-timeout 0 0
        line aux 0
        line vty 0 4
         login
        !
        no cns aaa enable
        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

        L2VPN pseudowire redundancy

        “L2VPN Pseudowire Redundancy” feature module in the MPLS Layer 2 VPNs Configuration Guide.

        H-VPLS

        “Configuring VPLS” in the “Configuring Multiprotocol Label Switching on the Optical Services Modules” chapter in the Optical Services Modules Installation and Configuration Notes, 12.2SR document.

        MPLS traffic engineering

        “MPLS Traffic Engineering Fast Reroute Link and Node Protection” feature module in the MPLS Traffic Engineering: Path, Link, and Node Protection Configuration Guide (part of the Multiprotocol Label Switching Configuration Guide Library)

        Standards

        Standard

        Title

        http://www.ietf.org/rfc/rfc4447.txt

        Pseudowire Setup and Maintenance Using the Label Distribution Protocol (LDP)

        http://www3.ietf.org/proceedings/06mar/IDs/draft-ietf-l2vpn-vpls-ldp-08.txt

        Virtual Private LAN Services over MPLS

        http://www.ietf.org/internet-drafts/draft-ietf-pwe3-segmented-pw-02.txt

        Segmented Pseudo Wire

        draft-ietf-pwe3-vccv-10.txt

        Pseudo Wire Virtual Circuit Connectivity Verification (VCCV)

        draft-ietf-pwe3-oam-msg-map-03.txt

        Pseudo Wire (PW) OAM Message Mapping

        MIBs

        MIB

        MIBs Link

        Pseudowire Emulation Edge-to-Edge MIBs for Ethernet, Frame Relay, and ATM Services

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

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

        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 L2VPN Pseudowire Switching

        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 L2VPN Pseudowire Switching

        Feature Name

        Releases

        Feature Information

        L2VPN Pseudowire Switching

        Cisco IOS XE Release 2.4

        The L2VPN Pseudowire Switching feature extends layer 2 virtual private network (L2VPN) pseudowires across an interautonomous system (inter-AS) boundary or across two separate multiprotocol label switching (MPLS) networks.

        In Cisco IOS XE Release 2.4, The L2VPN Pseudowire Switching feature is supported with Ethernet over MPLS.

        The following commands were introduced or modified: l2 vfi point-to-point, neighbor(L2VPN Pseudowire Switching), show vfi.