Switch Features 83IGMP Snooping QuerierWhen Protocol Independent Multicast (PIM) and IGMP are enabled in anetwork with IP multicast routing, the IP multicast router acts as the IGMPquerier. However, if it is desirable to keep the multicast network Layer 2switched only, the IGMP Snooping Querier can perform the query functionsof a Layer 3 multicast router.MLD SnoopingIn IPv4, Layer 2 switches can use IGMP Snooping to limit the flooding ofmulticast traffic by dynamically configuring Layer 2 interfaces so thatmulticast traffic is forwarded to only those interfaces associated with IPmulticast address.In IPv6, MLD snooping performs a similar function. With MLD snooping,IPv6 multicast data is selectively forwarded to a list of ports intended toreceive the data (instead of being flooded to all of the ports in a VLAN). Thislist is constructed by snooping IPv6 multicast control packets.Multicast VLAN RegistrationThe Multicast VLAN Registration (MVR) protocol, like IGMP Snooping,allows a Layer 2 switch to listen to IGMP frames and forward the multicasttraffic only to the receivers that request it. Unlike IGMP Snooping, MVRallows the switch to listen across different VLANs. MVR uses a dedicatedVLAN, which is called the multicast VLAN, to forward multicast traffic overthe Layer 2 network to the various VLANs that have multicast receivers asmembers.NOTE: MVR is not supported on the PowerConnect M6220.
