Operation Manual – MulticastH3C S7500E Series Ethernet Switches Chapter 2 IGMP Snooping Configuration2-14Caution:If fast leave processing is enabled on a port to which more than one host is attached,when one host leaves a multicast group, the other hosts attached to the port andinterested in the same multicast group will fail to receive multicast data for that group.2.5 Configuring IGMP Snooping Querier2.5.1 Configuration PrerequisitesBefore configuring IGMP Snooping querier, complete the following task:z Enable IGMP Snooping in the VLAN.Before configuring IGMP Snooping querier, prepare the following data:z IGMP general query interval,z IGMP last-member query interval,z Maximum response time to IGMP general queries,z Source address of IGMP general queries, andz Source address of IGMP group-specific queries.2.5.2 Enabling IGMP Snooping QuerierIn an IP multicast network running IGMP, a multicast router or Layer 3 multicast switchis responsible for sending IGMP general queries, so that all Layer 3 multicast devicescan establish and maintain multicast forwarding entries, thus to forward multicast trafficcorrectly at the network layer. This router or Layer 3 switch is called IGMP querier.However, a Layer 2 multicast switch does not support IGMP, and therefore cannot sendgeneral queries by default. By enabling IGMP Snooping on a Layer 2 switch in a VLANwhere multicast traffic needs to be Layer-2 switched only and no multicast routers arepresent, the Layer 2 switch will act as the IGMP Snooping querier to send IGMPqueries, thus allowing multicast forwarding entries to be established and maintained atthe data link layer.Follow these steps to enable IGMP Snooping querier:To do... Use the command... RemarksEnter system view system-view —Enter VLAN view vlan vlan-id —Enable IGMP Snoopingquerier igmp-snooping querier RequiredDisabled by default
