1-3After the configuration, upon receiving an IGMP message on a user port, Switch A tags the messagewith the multicast VLAN ID and relays it to the IGMP querier, so that IGMP Snooping can uniformlymanage the router ports and member ports in the multicast VLAN. When forwarding multicast data toSwitch A, Router A needs to send only one copy of multicast traffic to Switch A in the multicast VLAN,and Switch A distributes the traffic to all the member ports in the multicast VLAN.z For information about IGMP Snooping, router ports, and member ports, refer to IGMP SnoopingConfiguration in the IP Multicast Volume.z For information about VLAN tags, refer to VLAN Configuration in the Access Volume.Multicast VLAN Configuration Task ListComplete the following tasks to configure multicast VLAN:Task RemarksConfiguring Sub-VLAN-Based Multicast VLANConfiguring User Port AttributesConfiguring Port-BasedMulticast VLAN Configuring Multicast VLAN PortsRequiredUse either approach.If you have configured both sub-VLAN-based multicast VLAN and port-based multicast VLAN on adevice, the port-based multicast VLAN configuration is given preference.Configuring Sub-VLAN-Based Multicast VLANConfiguration PrerequisitesBefore configuring sub-VLAN-based multicast VLAN, complete the following tasks:z Create VLANs as requiredz Enable IGMP Snooping in the VLAN to be configured as a multicast VLANConfiguring Sub-VLAN-Based Multicast VLANIn this approach, you need to configure a VLAN as a multicast VLAN, and then configure user VLANs assub-VLANs of the multicast VLAN.Follow these steps to configure sub-VLAN-based multicast VLAN:
