MSDP Intra and Inter Domain Peerings Best Practices

In multicast network configurations, MSDP (Multicast Source Discovery Protocol) peerings can be categorized into intra-domain and inter-domain.

Intradomain peerings occur between Rendezvous Points (RPs) within the same domain and are essential for the proper functioning of Anycast RP scenarios. When there are only two RPs per domain, maintaining a single peering between them suffices.

Inter-domain peerings, on the other hand, connect RPs across different PIM (Protocol Independent Multicast) domains. For these inter-domain connections, a full mesh peering is not necessary—even for visibility across domains—since RPs within a domain already synchronize their Source-Active (SA) databases internally. Implementing unnecessary peerings, such as direct connections between non-adjacent RPs in different domains, can lead to increased control-plane overhead without added benefit.

The recommended practice for inter-domain MSDP peerings is to establish a partial mesh configuration like so, where the red dotted lines indicate an MSDP peering:

multicast-msdp-peerings.png

With this setup, you'll have redundancy and scalability while keeping it simple.

https://networklessons.com/multicast/multicast-anycast-rp-configuration-cisco-ios