Operation Manual – MulticastH3C S3100 Series Ethernet Switches Chapter 1 Multicast Overview1-101.3.2 Multicast ProtocolsNote:z Generally, we refer to IP multicast working at the network layer as Layer 3 multicastand the corresponding multicast protocols as Layer 3 multicast protocols, whichinclude IGMP, PIM, and MSDP; we refer to IP multicast working at the data link layeras Layer 2 multicast and the corresponding multicast protocols as Layer 2 multicastprotocols, which include IGMP Snooping.z This section provides only general descriptions about applications and functions ofthe Layer 2 and Layer 3 multicast protocols in a network. For details about theseprotocols, refer to the related chapters of this manual.I. Layer 3 multicast protocolsLayer 3 multicast protocols include multicast group management protocols andmulticast routing protocols. Figure 1-5 describes where these multicast protocols are ina network.AS 1 AS 2SourceReceiver ReceiverReceiverPIM PIMMSDPIGMP IGMPIGMPFigure 1-5 Positions of Layer 3 multicast protocols1) Multicast management protocolsTypically, the Internet Group Management Protocol (IGMP) is used between hosts andLayer 3 multicast devices directly connected with the hosts. These protocols define themechanism of establishing and maintaining group memberships between hosts andLayer 3 multicast devices.
