Managing IPv4 and IPv6 Multicast 1179What Multicast Protocols Does the Switch Support?Multicast protocols are used to deliver multicast packets from one source tomultiple receivers. Table 43-1 summarizes the multicast protocols that theswitch supports.What Are the Multicast Protocol Roles?Hosts must have a way to identify their interest in joining any particularmulticast group, and routers must have a way to collect and maintain groupmemberships. These functions are handled by the IGMP protocol in IPv4. InIPv6, multicast routers use the Multicast Listener Discover (MLD) protocolto maintain group membership information.Multicast routers must also be able to construct a multicast distribution treethat enables forwarding multicast datagrams only on the links that arerequired to reach a destination group member. Protocols such as DVMRP, andPIM handle this function.IGMP and MLD are multicast group discovery protocols that are usedbetween the clients and the local multicast router. PIM-SM, PIM-DM, andDVMRP are multicast routing protocols that are used across differentsubnets, usually between the local multicast router and remote multicastrouter.Table 43-1. Multicast Protocol Support SummaryProtocol IPv4 or IPv6 For Communication BetweenIGMP IPv4 Host-to-L3 switch/routerIGMP Proxy IPv4 Host-to-L3 switch/routerMLD IPv6 Host-to-L3 switch/routerMLD Proxy IPv6 Host-to-L3 switch/routerPIM-SM IPv4 and IPv6 L3-switch/router-to-L3 switch/routerPIM-DM IPv4 and IPv6 L3-switch/router-to-L3 switch/routerDVMRP IPv4 L3-switch/router-to-L3 switch/router
