Advanced Routing mode supports Multicast Source Discovery Protocol (MSDP) in PIM Sparse Mode (PIM-SM). MSDP-enabled firewalls in one domain can peer with MDSP-enabled devices in a different domain or autonomous system. The peers exchange control information and discover multicast sources outside their own domain. MSDP tracks active sources and shares them with configured peers. MSDP reduces the complexity of interconnecting multiple PIM-SM domains by allowing the domains to use an interdomain source tree.

MSDP uses well-known TCP port 639 for peering. Before you configure MSDP, be familiar with RFC 3618.

MSDP message types are Source Active (SA), Keepalive, and Notification messages.