Wholesale-retail multi-chassis redundancy

Multi-chassis redundancy for a retail service is enabled with the SRRP and redundant interface configuration on the wholesale group interface parented by the forwarding subscriber interface. The multi-chassis state (active or standby) of the retail subscriber host is determined from the SRRP state (master/non-master) of the group interface that parents the SAP of the retail subscriber host. The retail service ID must be equal on both nodes.

Sample wholesale service configuration:

 vprn 3000 customer 1 create
            description "Wholesale service"
            route-distinguisher 64500:3000
            auto-bind-tunnel
                resolution-filter
                    ldp
                    rsvp
                exit
                resolution filter
            exit
            vrf-target import target:64500:3000
            redundant-interface "red-int-1" create
                address 192.168.100.0/31
                ip-mtu 1500
                spoke-sdp 12:3000 create
                    no shutdown
            exit
            subscriber-interface "sub-int-1" create
                address 10.1.1.253/24 gw-ip-address 10.1.1.254
                address 10.1.2.253/24 gw-ip-address 10.1.2.254
                group-interface "group-int-1-1" create
                    dhcp
                        --- snip ---
                    exit
                    redundant-interface "red-int-1"
                    sap 1/1/6:1.4001 create
                        description "SRRP 1 message path"
                    exit
                    srrp 1 create
                        message-path 1/1/6:1.4001
                        send-fib-population-packets outer-tag-only
                        no shutdown
                    exit
                    pppoe
                        --- snip ---
                    exit
                exit
                group-interface "group-int-1-2" create
                    dhcp
                        --- snip ---
                    exit
                    redundant-interface "red-int-1"
                    sap 1/1/6:2.4001 create
                        description "SRRP 2 message path"
                    exit
                    srrp 2 create
                        message-path 1/1/6:2.4001
                        priority 50
                        send-fib-population-packets outer-tag-only
                        no shutdown
                    exit
                    pppoe
                        --- snip ---
                    exit
                exit
            exit
            no shutdown
        exit

Sample retail service configuration:

 vprn 3001 customer 1 create
            description "Retail service"
            route-distinguisher 64500:3001
            auto-bind-tunnel
                resolution-filter
                    ldp
                    rsvp
                exit
                resolution filter
            exit
            vrf-target target:64500:3001
            subscriber-interface "sub-int-rt-3000-1" fwd-service 3000 fwd-subscriber-
interface "sub-int-1" create
                address 10.1.11.253/24 gw-ip-address 10.1.11.254
                address 10.1.12.253/24 gw-ip-address 10.1.12.254
                dhcp
                    --- snip ---
                exit
                pppoe
                    --- snip ---
                exit
            exit
            no shutdown
        exit

Retail unnumbered host routes must be leaked in the wholesale service. Retail subscriber subnets and prefixes leaked in the wholesale service are needed to forward downstream shunted traffic over the redundant interface.

The address of an IPv4 unnumbered subscriber host (enabled with unnumbered {ip-int-name | ip-address} or allow-unmatching-subnets on the retail subscriber interface) is not contained in the subnets configured on the retail subscriber interface. The export of the IPv4 retail subscriber host routes to the wholesale service must be explicitly enabled with the export-host-routes command:

        vprn 3001 customer 1 create
            subscriber-interface "sub-int-rt-3000-1" fwd-service 3000 fwd-subscriber-
interface "sub-int-1" create
                allow-unmatching-subnets
                address 10.1.11.253/24 gw-ip-address 10.1.11.254
                address 10.1.12.253/24 gw-ip-address 10.1.12.254
                export-host-routes
                --- snip ---

The address of an IPv6 unnumbered subscriber host (enabled with ipv6 allow-unmatching-prefixes on the retail subscriber interface) is not contained in the IPv6 prefixes configured on the retail subscriber interface. IPv6 retail subscriber host routes are automatically exported to the wholesale service.

Downstream traffic arriving on a standby node (SRRP backup state) must be shunted over the redundant interface. Downstream traffic shunting can be reduced by advertising the retail subscriber subnets and prefixes from the active node (SRRP master state) with a more favorable metric using routing policies. To make retail subscriber subnets and prefixes SRRP state-aware, they have to be configured to track an SRRP instance that is active on a group interface of the connected wholesale subscriber interface:

        vprn 3001 customer 1 create
            subscriber-interface "sub-int-rt-3000-1" fwd-service 3000 fwd-subscriber-
interface "sub-int-1" create
                address 10.1.11.253/24 gw-ip-address 10.1.11.254 track-srrp 1
                address 10.1.12.253/24 gw-ip-address 10.1.12.254 track-srrp 2
                ---snip---
                ipv6
                    subscriber-prefixes
                        prefix 2001:db8:d001::/48 pd track-srrp 1
                        prefix 2001:db8:d002::/48 pd track-srrp 2
                        prefix 2001:db8:1:100::/56 wan-host track-srrp 1
                        prefix 2001:db8:1:200::/56 wan-host track-srrp 2
                    exit
                exit

Multi-chassis redundancy is supported for IPoE (IPv4 and IPv6) and PPPoE (IPv4 and IPv6) retail subscriber hosts and sessions.

Overlapping addresses on retail subscriber interfaces (enabled with config>service>vprn>subscriber-interface>private-retail-subnets) can be used in combination with multi-chassis redundancy.

When the private-retail-subnets command is enabled, downstream traffic arriving at retail services on a standby node (SRRP backup state) is shunted over to the redundant interface on a wholesale service. On a redundant interface, the service that each frame belongs to is identified by the source MAC address of the frame that includes service ID of a retailer service.

The service ID of each retailer service is synchronized over MCS. Therefore, service IDs for the retailer VPRN must be the same in both nodes.

Traffic shunting in the overlapping address scenario is supported for downstream traffic only.