Common notations in multicast
The following notations are commonly used in multicast transmission:
(*, G)—Rendezvous point tree (RPT), or a multicast packet that any multicast source sends to multicast group G. The asterisk (*) represents any multicast source, and "G" represents a specific multicast group.
(S, G)—Shortest path tree (SPT), or a multicast packet that multicast source "S" sends to multicast group "G." "S" represents a specific multicast source, and "G" represents a specific multicast group.
For more information about the concepts RPT and SPT, see "Configuring PIM."