V-273575

Discussion

The interoperability of BGP extensions for interdomain multicast routing and MSDP enables seamless connectivity of multicast domains between autonomous systems. MP-BGP advertises the unicast prefixes of the multicast sources used by Protocol Independent Multicast (PIM) routers to perform RPF checks and build multicast distribution trees. MSDP is a mechanism used to connect multiple PIM sparse-mode domains, allowing RPs from different domains to share information about active sources. When RPs in peering multicast domains hear about active sources, they can pass on that information to their local receivers, thereby allowing multicast data to be forwarded between the domains. Configuring an import policy to block multicast advertisements for reserved, Martian, single-source multicast, and any other undesirable multicast groups, as well as any source-group (S, G) states with Bogon source addresses, would assist in avoiding unwanted multicast traffic from traversing the core.

Check Content

Check for SA filter on MSDP peer:

ICX#  show msdp peer x.x.x.x | include Input

        Input SA Filter:Applicable
        Input (S,G) route-map:MSDP_SA_filter
        Input RP route-map:None

If any configured MSDP peer is not configured to filter undesirable multicast groups and sources, this is a finding.