Displaying and Maintaining IGMP Snooping 437■ If you configure IGMP Snooping simulated joining in Ethernet port view, theEthernet port must belong to the specified VLAN; otherwise the configurationdoes not take effect.■ You can use the source-ip source-address command to specify a multicastsource address that the port will join as a simulated host. This configurationtakes effect only when IMGPv3 Snooping is enabled in the VLAN.Configuring MulticastVLANIn the current multicast mode, when users in different VLANs order the samemulticast packet, the multicast stream is copied to each of the VLANs. This modewastes a lot of bandwidth.By configuring a multicast VLAN, adding switch ports to the multicast VLAN andenabling IGMP Snooping, you can make users in different VLANs share the samemulticast VLAN. This saves bandwidth because multicast streams are transmittedonly within the multicast VLAN and also guarantees security because the multicastVLAN is isolated from user VLANs completely. Therefore, multicast informationstreams can be transmitted to users continuously if multicast VLAN is configured.Perform the following configuration to configure multicast VLAN.c CAUTION:■ You can configure up to 5 multicast VLANs for the device.■ A multicast VLAN cannot be configured as a multicast sub-VLAN.■ A multicast sub-VLAN cannot be configured as a multicast VLAN.■ A multicast sub-VLAN cannot be configured as the sub-VLAN of anothermulticast VLAN.■ A multicast sub-VLAN is corresponding to a multicast VLAN only.■ If multicast routing is enabled on a VLAN interface, the corresponding VLANcannot be configured as a multicast VLAN.Displaying andMaintaining IGMPSnoopingAfter the configuration above, you can execute the display command to verifythe configuration by checking the displayed information.You can execute the reset command to clear the statistics information aboutIGMP Snooping.Table 349 Configure multicast VLANOperation Command DescriptionEnter system view system-view -Enable the IGMP snooping functiongloballyigmp-snooping enable RequiredEnter VLAN view vlan vlan-id -Enable the IGMP snooping function igmp-snooping enable RequiredEnable the multicast VLAN function multicast-vlan enable RequiredConfigure the mapping relationshipbetween multicast VLAN and multicastsub-VLANsmulticast-vlan vlan-id subvlanvlan-listRequired
