Configuring L2 Multicast Features 813Topologies Where the Multicast Source Is Not Directly Connected to theQuerierIf the multicast source is not directly connected to a multicast querier, themulticast stream is forwarded to any router ports on the switch (within theVLAN). Because multicast router queries are flooded to all ports in theVLAN, intermediate IGMP snooping switches will receive the multicaststream from the multicast source and forward it to the multicast router.Using Static Multicast MAC ConfigurationIf configuring static multicast MAC group addresses on a port in a VLAN, it isnecessary to configure all ports in the VLAN over which it is desired that thegroup traffic flow (both host and router) on all switches. IGMP snooping doesnot dynamically add ports to a VLAN for a multicast group when a staticentry is configured for that group in the VLAN. This restriction applies toboth multicast router-connected ports and host-connected ports.IGMP Snooping and GMRPIGMP snooping and GMRP are not compatible. Only one of IGMP snoopingor GMRP should be configured to filter multicast groups for any VLAN.Simultaneous operation of GMRP and IMGP snooping is not supported andwill lead to undesirable results, such as flooding in the VLAN due to theinability to identify multicast router ports.
