Configuring Pseudowire Group Switchover

Pseudowire Group Switchover Configuration

This chapter provides information about the Pseudowire Group Switchover feature on the Cisco ASR 903 Router.

Prerequisites for Pseudowire Group Switchover

  • This feature is supported only by Cisco IOS Release 15.3(3)S or later.
  • The remote provider edge (PE) router should be capable of sending group status messages.
  • Cisco ASR 903 cannot generate pseudowire group status messages. It can only process the message. To use the pseudowire group switchover feature, the Cisco ASR 903 must be connected with a router that supports the sending of group status messages.

Restrictions for Pseudowire Group Switchover

Cisco ASR 903 supports pseudowire group switchover for Ethernet, Asynchronous Transfer Mode (ATM), and T1/E1 circuit emulation (CEM) pseudowires. However, due to current limitations on Cisco ASR 9000, Ethernet pseudowire switchover in less than one second is not supported.

Pseudowire Group Switchover

Currently, pseudowire switchovers to the backup pseudowires occur one by one from IOS to platform dataplane and can take up to four seconds for 1000 pseudowires. The group switchover feature reduces this switchover time by efficiently grouping status messages in both Label Distribution Protocol (LDP) and internal Inter-Process Communications (IPCs). Using group switchover feature, 1000 pseudowires can be switched to their backup pseudowires in less than one second.


Note

The Pseudowire Group Switchover feature is enabled by default and cannot be disabled.

Configuring Predictive Switchover

In a Multi-Chassis Link Aggregation Group (MC-LAG) or multichassis LACP (mLACP) scenario, predictive switchover improves the performance when the remote PE router’s standby pseudowire advertises down (standby) state to the local PE router. This scenario is also applicable for automatic protection switching (APS) for CEM and ATM.

Without predictive switchover, the active pseudowire has to wait for the standby pseudowire to be up before it does a switchover. With predictive switchover configured, the active pseudowire immediately switches over to the standby pseudowire as soon as the active pseudowire goes down, even if the remote state of the standby pseudowire is standby.

Depending on the requirement, the predictive switchover can be configured using either of the following methods:

Configuring Predictive Switchover on Global Configuration Mode

SUMMARY STEPS

    1.    enable

    2.    configure terminal

    3.    l2vpn

    4.    redundancy predictive enabled

    5.    end


DETAILED STEPS
     Command or ActionPurpose
    Step 1enable


    Example: 
    Router> enable
          		Enables privileged EXEC mode
    • Enter your password if prompted.
     
    Step 2configure terminal


    Example: 
    Router# configure terminal
          		Enters global configuration mode.  
    Step 3l2vpn


    Example: 
    Router(config)# l2vpn
     

    Enters Layer 2 VPN (L2VPN) configuration mode.

    To return to the default behavior, use the no form of this command.

     
    Step 4redundancy predictive enabled


    Example: 
    Router(config-l2vpn)# redundancy predictive enabled
     

    Enables redundancy predictive mode.

    To disable redundancy predictive mode, use the no form of the command.

    By default, redundancy predictive mode is disabled.

     
    Step 5end


    Example: 
    Router(config-l2vpn)# end
          		Returns to privileged EXEC mode.  

    Configuring Predictive Switchover on per Cross Connect basis

    SUMMARY STEPS

      1.    enable

      2.    configure terminal

      3.    l2vpn xconnect context context-name

      4.    redundancy predictive {enabled | disabled}

      5.    end


    DETAILED STEPS
       Command or ActionPurpose
      Step 1enable


      Example: 
      Router> enable
       

      Enables privileged EXEC mode.

      Enter your password if prompted.

       
      Step 2configure terminal


      Example: 
      Router# configure terminal
              		Enters global configuration mode.  
      Step 3l2vpn xconnect context context-name


      Example: 
      Router(config)# l2vpn xconnect context con1
       

      Creates a L2VPN cross connect context and enters cross connect configuration mode.

      context-name—Name of the cross connect context.

      To remove the connection, use the no form of this command.

       
      Step 4redundancy predictive {enabled | disabled}


      Example: 
      Router(config-xconnect)# redundancy predictive enabled
       

      Enables redundancy predictive mode.

      enabled—enables the predictive mode.

      disabled—disables the predictive mode.

       
      Step 5end


      Example: 
      Router(config-xconnect)# end
              		Returns to privileged EXEC mode.  

      Verifying Pseudowire Group Switchover Configurations

      You can use various show commands to view information specific to pseudowire group switchover configurations.

      The following example displays information about Any Transport over MPLS (AToM) virtual circuits (VCs): 

      
Router# show l2vpn atom vc destination 2.2.2.2 group remote 100663808

                                       Service
Interface Dest Address    VC ID      Type   Name                     Status
--------- --------------- ---------- ------ ------------------------ ----------
pw100041  2.2.2.2         1000       p2p    AT0/5/1.1/1/1.1:10/1000  UP

      The following example display status of the pseudowire switching point: 

      
Router# show l2vpn atom vc destination 2.2.2.2 group remote 100663808 detail

pseudowire100041 is up, VC status is up PW type: ATM AAL5
  Create time: 01:17:42, last status change time: 00:01:55
    Last label FSM state change time: 01:17:41
  Destination address: 2.2.2.2 VC ID: 1000
    Output interface: Gi0/3/3, imposed label stack {16003}
    Preferred path: not configured
    Default path: active
    Next hop: 11.0.0.2
  Member of xconnect service AT0/5/1.1/1/1.1:10/1000, group right
    Associated member AT0/5/1.1/1/1.1 is up, status is up
    Interworking type is Like2Like
    Service id: 0xb6000015
  Signaling protocol: LDP, peer 2.2.2.2:0 up
    Targeted Hello: 1.1.1.1(LDP Id) -> 2.2.2.2, LDP is UP
    Graceful restart: configured and enabled
    Non stop routing: not configured and not enabled
    PWid FEC (128), VC ID: 1000
    Status TLV support (local/remote)         : enabled/supported
      LDP route watch                         : enabled
      Label/status state machine              : established, LruRru
      Local dataplane status received         : No fault
      BFD dataplane status received           : Not sent
      BFD peer monitor status received        : No fault
      Status received from access circuit     : No fault
      Status sent to access circuit           : No fault
      Status received from pseudowire i/f     : No fault
      Status sent to network peer             : No fault
      Status received from network peer       : No fault
      Adjacency status of remote peer         : No fault
  Sequencing: receive disabled, send disabled
  Bindings
    Parameter    Local                          Remote
    ------------ ------------------------------ ------------------------------
    Label        514                            16003
    Group ID     0                              100663808
    Interface                                   ATM0_1_0_0.1
    MTU          4470                           4470
    Control word on (configured: autosense)     on
    PW type      ATM AAL5                       ATM AAL5
    VCCV CV type 0x02                           0x02
                   LSPV [2]                       LSPV [2]
    VCCV CC type 0x02                           0x07
                   RA [2]                        CW [1], RA [2], TTL [3]
    Status TLV   enabled                        supported
  SSO Descriptor: 2.2.2.2/1000, local label: 514
  Dataplane:
    SSM segment/switch IDs: 4114/4096 (used), PWID: 41
  Rx Counters
    24 input transit packets, 1872 bytes
    0 drops, 0 seq err
  Tx Counters
    27611 output transit packets, 5466978 bytes
    0 drops

      The following example lists the active/standby segment pairs associated with each peer IP address and group identifier: 

      
Router# show ssm group

Active                 Standby
IP Address         Group ID     Segment/Switch         Segment/Switch
=========================================================================
2.2.2.2           100663808     7384593/7224772        7380496/7228869

      The following example displays the number of active/standby segment pairs associated with each peer IP address and group identifier : 

      
Router# show ssm group 2.1.1.2 6 summary

IP Address         Group ID     Group Members
=============================================
2.2.2.2           100663808             900

      The following example displays the number of pseudowires programmed in hardware with grouping: 

      
Router# show platform hardware pp active pw eompls group brief

Brief L2VPN EoMPLS Pseudo Wire Group Info

IP address            Group ID         Count
                                       ------------------------------------------------------
0x02020202            100663808        900

      Troubleshooting the Pseudowire Group Switchover Configuration


      Caution

      We suggest you do not use the debug command without TAC supervision.

      Use the debug platform software atom brief command to get details on Add Group, Delete From Group, and Group Switchovers.