V-283850

Discussion

The interoperability of Border Gateway Protocol (BGP) extensions for interdomain multicast routing and MSDP enables seamless connectivity of multicast domains between autonomous systems. Multiprotocol BGP (MP-BGP) advertises the unicast prefixes of the multicast sources used by Protocol Independent Multicast (PIM) routers to perform Reverse Path Forwarding (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 Rendezvous Points (RPs) in peering multicast domains hear about active sources, they can pass that information on 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

Review the Nokia router configuration to determine if there is export policy to block local source-active multicast advertisements.

Use the command below to view the details of the policy:

- show router policy "MSDP-IMPORT-SA"
    entry 10
        from
            prefix-list "Multicast Group and Source"
        exit
        action drop
        exit
    exit

Verify the appropriate "Import Policy" has been applied to msdp peers using the command below:

- show router msdp peer detail | match "Import Policy"
Import Policy      : MSDP-IMPORT-SA

Verify an export policy is bound to each MSDP peer. 

If no export policy is applied, this is a finding.