116Configuring IGMP fast-leave processingIn some applications, such as ADSL dial-up networking, only one multicast receiver host is attached to aport of the IGMP querier. To allow fast response to the leave messages of the host when it switchesfrequently from one multicast group to another, you can enable IGMP fast-leave processing on the IGMPquerier.With IGMP fast-leave processing enabled, after receiving an IGMP leave message from a host, the IGMPquerier directly sends a leave notification to the upstream without sending IGMP group-specific queriesor IGMP group-and-source-specific queries. Thus, the leave latency is reduced on one hand, and thenetwork bandwidth is saved on the other hand.Configuration guidelines• The IGMP fast-leave processing configuration is effective only if the switch is running IGMPv2 orIGMPv3.• The IGMP fast-leave processing configuration is effective on Layer 3 interfaces other than VLANinterfaces, including Layer 3 Ethernet ports, Layer 3 aggregate interfaces, and Tunnel interfaces.Configuration procedureTo configure IGMP fast-leave processing globally:Step Command Remarks1. Enter system view. system-view N/A2. Enter public network IGMPview or VPN instance IGMPview.igmp [ vpn-instancevpn-instance-name ] N/A3. Configure IGMP fast-leaveprocessing.fast-leave [ group-policyacl-number ] Disabled by defaultTo configure IGMP fast-leave processing on an interface:Step Command Remarks1. Enter system view. system-view N/A2. Enter interface view. interface interface-typeinterface-number N/A3. Configure IGMP fast-leaveprocessing.igmp fast-leave [ group-policyacl-number ] Disabled by defaultIGMP fast-leave processing is implemented by IGMP snooping. For more information, see "ConfiguringIGMP snooping."
