PIM Source Specific Multicast Support

The threat defense device does not support PIM Source Specific Multicast (SSM) functionality and related configuration. However, the threat defense device allows SSM-related packets to pass through unless it is placed as a last-hop router.

SSM is classified as a data delivery mechanism for one-to-many applications such as IPTV. The SSM model uses a concept of "channels" denoted by an (S,G) pair, where S is a source address and G is an SSM destination address. Subscribing to a channel is achieved by using a group management protocol such as IGMPv3. SSM enables a receiving client, once it has learned about a particular multicast source, to receive multicast streams directly from the source rather than receiving it from a shared Rendezvous Point (RP). Access control mechanisms are introduced within SSM providing a security enhancement not available with current sparse or sparse-dense mode implementations.

PIM-SSM differs from PIM-SM in that it does not use an RP or shared trees. Instead, information on source addresses for a multicast group is provided by the receivers through the local receivership protocol (IGMPv3) and is used to directly build source-specific trees.