Bidirectional Protocol Independent Multicast (bidir-PIM) is best suited for many-to-many applications, such as conferencing and multiplayer gaming. Bidir-PIM enables designated forwarder (DF) routers to forward multicast traffic up the shared tree directly to multicast receivers; the router with the lowest cost to the rendezvous point (RP) is elected as the DF for that network segment. By contrast, unidirectional PIM implementations, such as PIM sparse mode (PIMSM), use a designated router (DR), which forwards multicast traffic from the multicast sources directly to the RP. The RP then sends the multicast traffic down the shared tree.

The router with the highest IP address is elected as the DR for that network segment.

Source Specific Multicast (SSM) is best suited for one-to-many applications, which are also called broadcast applications. One-to-many applications include streaming multimedia and other push-based applications. Each application must use a separate multicast group. The Internet Assigned Numbers Authority (IANA) has reserved the IPv4 multicast address range 232.0.0.0/8 and the IPv6 multicast address range of FF3x::/32 for use with SSM. When SSM is used, a multicast host can specify the source addresses from which they will accept multicast traffic.

Cisco provides no specific recommendations for applications to be used with PIM dense mode (PIMDM) or PIMSM. PIMDM routers initially add all the dense mode interfaces to the multicast routing table, flood multicast traffic out all available interfaces, and then prune back those interfaces that have no multicast receivers. By contrast, PIMSM routers add an interface to the multicast routing table only when a device connected through that interface joins the multicast group.