Operation Manual – MulticastH3C S3100 Series Ethernet Switches Chapter 2 IGMP Snooping Configuration2-11Note:z To prevent bursting traffic in the network or performance deterioration of the devicecaused by excessive multicast groups, you can set the maximum number ofmulticast groups that the switch should process.z When the number of multicast groups exceeds the configured limit, the switchremoves its multicast forwarding entries starting from the oldest one. In this case,the multicast packets for the removed multicast group(s) will be flooded in the VLANas unknown multicast packets. As a result, non-member ports can receive multicastpackets within a period of time. To avoid this from happening, enable the function ofdropping unknown multicast packets.2.2.7 Configuring IGMP Snooping QuerierNote:Only the S3100-EI series support the IGMP Snooping querier feature.In 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 querier on a Layer 2 switch in aVLAN where multicast traffic needs to be Layer-2 switched only and no multicastrouters are present, the Layer 2 switch will act as a querier to send IGMP generalqueries, thus allowing multicast forwarding entries to be established and maintained atthe data link layer.You can also configure the source address, maximum response time and interval ofgeneral queries to be sent from the IGMP Snooping querier.Table 2-11 Configure IGMP Snooping querierOperation Command RemarksEnter system view system-view —Enable IGMP Snooping igmp-snooping enableRequiredBy default, IGMPSnooping is disabled.Enter VLAN view vlan vlan-id —
