Operation Manual – MulticastH3C S3100 Series Ethernet Switches Chapter 2 IGMP Snooping Configuration2-152.2.11 Configuring a VLAN Tag for Query MessagesBy configuring the VLAN in which IGMP general and group-specific queries forwardedand sent by IGMP Snooping switches are transmitted, you can enable multicast packetforwarding between different VLANs In a Layer-2 multicast network environment.Table 2-17 Configure VLAN Tag for query messageOperation Command RemarksEnter system view system-view —Enable IGMP Snooping igmp-snooping enableRequiredBy default, IGMPSnooping is disabled.Configure a VLAN tag forquery messagesigmp-snoopingvlan-mapping vlanvlan-idRequiredNote:It is not recommended to configure this function while the multicast VLAN function is ineffect.2.2.12 Configuring Multicast VLANIn traditional multicast implementations, when users in different VLANs listen to thesame multicast group, the multicast data is copied on the multicast router for eachVLAN that contains receivers. This is a big waste of network bandwidth.In an IGMP Snooping environment, by configuring a multicast VLAN and adding portsto the multicast VLAN, you can allow users in different VLANs to share the samemulticast VLAN. This saves bandwidth because multicast streams are transmitted onlywithin the multicast VLAN. In addition, because the multicast VLAN is isolated fromuser VLANs, this method also enhances the information security.Multicast VLAN is mainly used in Layer 2 switching, but you must make thecorresponding configurations on the Layer 3 switch.Table 2-18 Configure multicast VLAN on the Layer 3 switchOperation Command RemarksEnter system view system-view —Create a multicast VLANand enter VLAN view vlan vlan-id —
