Terminology for Layer 2 Multicast

Terms

Term	Definition
(*, G)	A multicast routing entry used in the ASM model. * indicates any source, and G indicates a multicast group. (, G) applies to all multicast messages with the multicast group address as G. That is, all the multicast messages sent to G are forwarded through the downstream interface of the (, G) entry, regardless of which multicast sources send the multicast messages.
(S, G)	A multicast routing entry used in the SSM model. S indicates a multicast source, and G indicates a multicast group. After a multicast packet with S as the source address and G as the group address reaches a router, it is forwarded through the downstream interfaces of the (S, G) entry. A multicast packet that contains a specified source address is expressed as an (S, G) packet.

Term

Definition

(*, G)

A multicast routing entry used in the ASM model. * indicates any source, and G indicates a multicast group.

(*, G) applies to all multicast messages with the multicast group address as G. That is, all the multicast messages sent to G are forwarded through the downstream interface of the (*, G) entry, regardless of which multicast sources send the multicast messages.

(S, G)

A multicast routing entry used in the SSM model. S indicates a multicast source, and G indicates a multicast group.

After a multicast packet with S as the source address and G as the group address reaches a router, it is forwarded through the downstream interfaces of the (S, G) entry.

A multicast packet that contains a specified source address is expressed as an (S, G) packet.

Acronyms and Abbreviations

Acronym and Abbreviation	Full Name
IGMP	Internet Group Management Protocol
PIM	Protocol Independent Multicast
PW	pseudo wire
VLAN	virtual local area network
VPLS	virtual private LAN service
VSI	virtual switch instance