PIM snooping for IPv4 synchronization

MCS for PIM snooping for IPv4 synchronizes the neighbor information from PIM hellos and join/prune state information from PIM for IPv4 messages received on the related SAPs and spoke-SDPs corresponding to the sync-tag associated with the related ports and SDPs, respectively. Use the following CLI syntax to enable MCS for PIM snooping for IPv4 synchronization.

CLI syntax:

configure
   redundancy
     multi-chassis
       peer ip-address [create]
         sync
           pim-snooping [saps] [spoke-sdps]

Any PIM hello state information received over the MCS connection from the peer router takes precedence over locally snooped hello information. This ensures that any PIM hello messages received on the active router that are then flooded, for example through the network backbone, and received over a local SAP or SDP on the standby router are not inadvertently used in the standby router’s VPLS service.

The synchronization of PIM snooping state is only supported for manually configured spoke-SDPs. It is not supported for spoke-SDPs configured within an endpoint.

When synchronizing the PIM state between two spoke-SDPs, if both spoke-SDPs go down, the PIM state is maintained on both until one becomes active to ensure that the PIM state is preserved when a spoke-SDP recovers.

Appropriate actions based on the expiration of PIM-related timers on the standby router are only taken after it has become the active peer for the related object (after a failover).

PIM snooping for IPv4 synchronization is supported wherever PIM snooping for IPv4 is supported, excluding the following services:

BGP-VPLS
VPLS E-Tree
management VPLS

See PIM snooping for VPLS for more details.

PIM snooping for IPv4 synchronization is also only supported for the following active/standby redundancy mechanisms on dual-homed systems:

MC-LAG
BGP multihoming
active/standby pseudowires
single-active multihoming (EVPN-MPLS and PBB-EVPN I-VPLS)

Configuring an mrouter port under an object that has the synchronization of PIM snooping for IPv4 states enabled is not recommended. The mrouter port configuration adds a (*,*) entry into the MFIB, which causes all groups (and PIM messages) to be sent out of the respective object. In addition, the mrouter-port command causes all PIM messages on that object to be discarded. However, the (*,*) entry is not synchronized by MCS. Consequently, the mrouter port could cause the two MCS peers to be forwarding different sets of multicast streams out of the related object when each is active.