Epipe-based aggregation service

For an Epipe based aggregation service, the redundancy is based on active/standby PWs from A-PE to the redundant BNG pair. A-PE signals active and standby pseudowire status to the BGN pair. An SRRP instance per PW port (group interface) is required on the BNG with a messaging SAP on each PW port. The SRRP instance on a PW port is in the SRRP master state when the PW is active and in the SRRP backup state when the PW is standby. This is achieved by tying the SRRP state to the state of the messaging SAP. The messaging SAP goes down when the underlying PW port goes down based on the PW status bit signaled by the A-PE.

In this model, there is no SRRP message exchange between the BNG pair, as there is no Layer 2 path between them. The purpose of SRRP is to get SRRP-aware routing for subscriber routes and managed routes, or to be able to use the redundant (shunt) interface. Downstream traffic for a subscriber that ingresses the standby BNG can only be shunted to the active BNG, if the corresponding subscriber interface on the standby BNG is operationally UP. This is achieved by creating a second empty group interface (without SAPs) on the same subscriber interface with the oper-up-while-empty command configured. Multiple PWs with endpoint configuration is not supported on the BNG.

Figure: BNG redundancy based on active/standby PW signaling

Sample configuration on an active BNG

config>
    pw-port 2 create
    exit 

config>redundancy# 
     multi-chassis
         peer 10.20.1.3 create
             source-address 10.20.1.2
                sync
                    srrp
                    sub-mgmt ipoe pppoe
                    port pw-2 sync-tag "tag2" create
                    exit
                    no shutdown
                exit
                no shutdown
            exit 
        exit
     exit 

config>service>ies#
       redundant-interface "redundant-interface" create
          address 10.10.30.2/24 remote-ip 10.10.30.3
          spoke-sdp 23:1000 create
             no shutdown
          exit
       exit
config>service#
    sdp 1 mpls create
       far-end 10.20.1.2
       ldp
       keep-alive
          shutdown
       exit
       binding
          port 1/1/1
          pw-port 2 vc-id 2 create
             vc-type vlan        #### default encaps-type dot1Q
             no shutdown 
          exit
       exit
       no shutdown
    exit
config>service#            
       subscriber-interface "subif" create
           address 10.11.1.2/16 gw-ip-address 10.11.1.1 populate-host-routes
                group-interface "grpif" create
                    authentication-policy "base_authpolicy"
                    redundant-interface "redundant-interface"
                    sap pw-2:1000 create
                        description "sap-grp-3"
                    exit
                    srrp 1 create
                        message-path pw-2:1000
                        no shutdown
                    exit
                    arp-host
                        host-limit overall 8000
                        min-auth-interval 1
                        no shutdown
                    exit
                exit
            exit
        exit  

Sample configuration on a standby BNG

config>
    pw-port 2 create
    exit 
config>redundancy# 
     multi-chassis
         peer 10.20.1.2 create
             source-address 10.20.1.3
                sync
                    srrp
                    sub-mgmt ipoe pppoe
                    port pw-2 sync-tag "tag2" create
                    exit
                exit
                no shutdown
            exit 
        exit
     exit 
config>service>ies#
       redundant-interface "redundant-interface" create
          address 10.10.30.3/24 remote-ip 10.10.30.2
          spoke-sdp 32:1000 create
             no shutdown
          exit
       exit
config>service#
    sdp 1 mpls create
       far-end 10.20.1.2
       ldp
       keep-alive
          shutdown
       exit
       binding
          port 1/1/1
          pw-port 2 vc-id 2 create
             vc-type vlan        #### default encaps-type dot1Q
             no shutdown 
          exit
       exit
       no shutdown
    exit
config>service#            
       subscriber-interface "subif" create
           address 10.11.1.3/16 gw-ip-address 10.11.1.1 populate-host-routes
                group-interface "grpif" create
                    authentication-policy "base_authpolicy"
                    redundant-interface "redundant-interface"
                    sap pw-2:1000 create
                        description "sap-grp-3"
                    exit
                    srrp 1 create
                        keep-alive-interval 1
                        message-path pw-2:1000
                        no shutdown
                    exit
                    arp-host
                        host-limit 8000
                        min-auth-interval 1
                        no shutdown
                    exit
                exit
                group-interface "dummy" create
                    oper-up-while-empty
                exit
            exit
        exit