1160 Managing IPv4 and IPv6 MulticastWhen Is L3 Multicast Required on the Switch?You use the IPv4/IPv6 multicast feature on the PowerConnect 8000-series and8100-series switches to route multicast traffic between VLANs on the switch.If all hosts connected to the switch are on the same subnet, there is no needto configure the IP/IPv6 multicast feature. If the switch does not handle L3routing, you can use IGMP snooping or MLD snooping to manage port-basedmulticast group membership. For more information, see "What Is IGMPSnooping?" on page 683 and "What Is MLD Snooping?" on page 683. If thelocal network does not have a multicast router, you can configure the switchto act as the IGMP querier. For more information, see "IGMP SnoopingQuerier" on page 683.If the switch is configured as a L3 switch and handles inter-VLAN routingthrough static routes, OSPF, or RIP, and multicast traffic is transmittedwithin the network, enabling and configuring L3 multicast routing on theswitch is recommended.Determining Which Multicast Protocols to EnableIGMP is recommended on any switch that participates in IPv4 multicasting.MLD is recommended on any switch that participates in IPv6 multicasting.PIM-DM, PIM-SM, and DVMRP are multicast routing protocols that helpdetermine the best route for IP (PIM and DVMRP) and IPv6 (PIM) multicasttraffic. For more information about when to use PIM-DM, see "Using PIM-DM as the Multicast Routing Protocol" on page 1164. For more informationabout when to use PIM-SM, see "Using PIM-SM as the Multicast RoutingProtocol" on page 1163. For more information about when to configureDVMRP, see "Using DVMRP as the Multicast Routing Protocol" onpage 1166.What Is the Multicast Routing Table?Multicast capable/enabled routers forward multicast packets based on theroutes in the Multicast Routing Information Base (MRIB). These routes arecreated in the MRIB during the process of building multicast distributiontrees by the Multicast Protocols running on the router. Different IP Multicastrouting protocols use different techniques to construct these multicastdistribution trees.
