2-12It is meaningless to configure an IGMP Snooping querier in a multicast network running IGMP.Although an IGMP Snooping querier does not take part in IGMP querier elections, it may affect IGMPquerier elections because it sends IGMP general queries with a low source IP address.Configuring IGMP Queries and ResponsesYou can tune the IGMP general query interval based on actual condition of the network.Upon receiving an IGMP query (general query or group-specific query), a host starts a timer for eachmulticast group it has joined. This timer is initialized to a random value in the range of 0 to themaximum response time (the host obtains the value of the maximum response time from the MaxResponse Time field in the IGMP query it received). When the timer value comes down to 0, the hostsends an IGMP report to the corresponding multicast group.An appropriate setting of the maximum response time for IGMP queries allows hosts to respond toqueries quickly and avoids bursts of IGMP traffic on the network caused by reports simultaneously sentby a large number of hosts when the corresponding timers expire simultaneously.z For IGMP general queries, you can configure the maximum response time to fill their MaxResponse time field.z For IGMP group-specific queries, you can configure the IGMP last-member query interval to filltheir Max Response time field. Namely, for IGMP group-specific queries, the maximum responsetime equals to the IGMP last-member query interval.Configuring IGMP queries and responses globallyFollow these steps to configure IGMP queries and responses globally:To do... Use the command... RemarksEnter system view system-view —Enter IGMP Snooping view igmp-snooping —Configure the maximumresponse time to IGMP generalqueriesmax-response-time interval Optional10 seconds by defaultConfigure the IGMPlast-member query interval last-member-query-interval interval Optional1 second by defaultConfiguring IGMP queries and responses in a VLANFollow these steps to configure IGMP queries and responses in a VLAN:To do... Use the command... RemarksEnter system view system-view —Enter VLAN view vlan vlan-id —Configure IGMP general queryintervaligmp-snooping query-intervalintervalOptional60 seconds by default
