MSDP can operate in a mesh-group topology. A mesh-group limits the flooding of SA messages to neighboring peers. In a mesh-group, every MSDP peer must be connected to every other peer in the group. In this fully-meshed topology, when an SA message is received from a member of the mesh-group, the SA message is always accepted, but not flooded to other members of the same group. Because MSDP peers are connected to every other peer in the mesh-group, an MSDP peer is not required to forward SA messages to other members of the same mesh-group. However, SA messages are flooded to members of other mesh-groups. An MSDP mesh-group is an easy way to implement inter-domain multicast, as it relaxes the requirement to validate looping of MSDP control traffic (that is, peer-RPF checking is not required). Consequently, SA messages do not loop in the network.
Note
We recommend that you configure anycast RP peers in a mesh topology.