MSDP support for VPNs
Interfaces on the multicast devices in a VPN can set up MSDP peering relationships with each other. With the SA messages exchanged between MSDP peers, the multi-instance VPN implements the forwarding of multicast data across different PIM-SM domains.
To support MSDP for VPNs, a multicast device that runs MSDP maintains an independent set of MSDP mechanism for each VPN that it supports. These mechanisms include SA message cache, peering connection, timers, sending cache, and cache for exchanging PIM messages.
One VPN is isolated from another, and MSDP and PIM-SM messages can be exchanged only within the same VPN.