6-15Configuring Multicast VLANIn traditional multicast implementations, when users in different VLANs listen to the same multicastgroup, the multicast data is copied on the multicast router for each VLAN that contains receivers. This isa big waste of network bandwidth.In an IGMP Snooping environment, by configuring a multicast VLAN and adding ports to the multicastVLAN, you can allow users in different VLANs to share the same multicast VLAN. This saves bandwidthbecause multicast streams are transmitted only within the multicast VLAN. In addition, because themulticast VLAN is isolated from user VLANs, this method also enhances the information security.Multicast VLAN is mainly used in Layer 2 switching, but you must make the correspondingconfigurations on the Layer 3 switch.Follow these steps to configure multicast VLAN on the Layer 3 switch:To do... Use the command... RemarksEnter system view system-view —Create a multicast VLAN and enterVLAN view vlan vlan-id —Return to system view quit —Enter VLAN interface view interface Vlan-interface vlan-id —Enable IGMP igmp enableRequiredBy default, the IGMP feature isdisabled.Return to system view quit —Enter Ethernet port view for theLayer 2 switch to be configuredinterface interface-typeinterface-number —Define the port as a trunk or hybridport port link-type { trunk | hybrid } Requiredport hybrid vlan vlan-id-list{ tagged | untagged }Specify the VLANs to be allowed topass the Ethernet portport trunk permit vlan vlan-listRequiredThe multicast VLAN defined on theLayer 2 switch must be included,and the port must be configured toforward tagged packets for themulticast VLAN if the port type ishybrid.Follow these steps to configure multicast VLAN on the Layer 2 switch:To do... Use the command... RemarksEnter system view system-view —Enable IGMP Snooping igmp-snooping enable —Enter VLAN view vlan vlan-id —Enable IGMP Snooping igmp-snooping enable RequiredEnable multicast VLAN service-type multicast RequiredReturn to system view quit —Enter Ethernet port view for theLayer 3 switchinterface interface-typeinterface-number —
