Layer 3 Routing Commands 1423IGMPv2 introduced a Leave Group message, which is sent by a host when itleaves a multicast group for which it was the last host to send an IGMPReport message. Receipt of this message causes the Querier possibly toreduce the remaining lifetime of its state for the group, and to send a group-specific IGMP Query message to the multicast group.The Leave Groupmessage is not used with IGMPv3, since the source address filteringmechanism provides the same functionality.IGMPv3 also allows hosts to specify the list of hosts from which they want toreceive traffic. Traffic from other hosts is blocked inside the network. It alsoallows hosts to block packets for all sources sending unwanted traffic.IGMPv3 adds the capability for a multicast router to learn which sources areof interest to neighboring systems for packets sent to any particular multicastaddress. This information gathered by IGMP is provided to the multicastrouting protocol (that is, DVMRP, PIM-DM, and PIM-SM) that is currentlyactive on the router in order to ensure multicast packets are delivered to allnetworks where there are interested receivers.IGMP mode is automatically enabled when PIM, DVMRP, or IGMP Proxy isenabled.Commands in this SectionThis section explains the following commands:ip igmp last-member-query-countUse the ip igmp last-member-query-count command in InterfaceConfiguration mode to set the number of Group-Specific Queries sent beforethe router assumes that there are no local members on the interface.ip igmp last-member-query-count ip igmp startup-query-intervalip igmp last-member-query-interval ip igmp versionip igmp mroute-proxy show ip igmpip igmp query-interval show ip igmp groupsip igmp query-max-response-time show ip igmp interfaceip igmp robustness show ip igmp membershipip igmp startup-query-count show ip igmp interface stats
