Specifying Immediate-Leave Host Removal for IGMP

The immediate leave setting is useful for minimizing the leave latency of IGMP memberships when IGMP Version 2 is used and only one receiver host is connected to each interface. The routing device removes the host from the multicast group as soon as the routing device receives a leave group message from the host associated with the interface.

Use this statement only on IGMP version 2 (IGMPv2) interfaces to which one IGMP host is connected. If more than one IGMP host is connected to a LAN through the same interface, and one host sends a leave group message, the router removes all hosts on the interface from the multicast group. The routing device loses contact with the hosts that must remain in the multicast group until they send join requests in response to the routing device’s next general group membership query.

When immediate leave is enabled on a routing device running IGMPv2, and after receiving a leave group membership message from a host associated with the interface, the routing device immediately removes the group membership from the interface and suppresses the sending of any group-specific queries for the multicast group.

When immediate leave is enabled on a routing device running IGMP version 3 (IGMPv3), and after the routing device receives a report containing the type BLOCK_OLD_SOURCES, the routing device suppresses the sending of group-and-source queries but relies on the host tracking mechanism supported by Junos OS to determine whether or not it removes a particular source group membership from the interface.

When immediate leave is disabled and one host sends a leave group message, the routing device first sends a group query to determine if another receiver responds; if no other receivers respond, the routing device removes all hosts on the interface from the multicast group. Immediate leave is disabled by default.

To enable immediate leave for an interface:

Configure immediate leave on the IGMP interface.
[edit]user@host# edit protocols igmpuser@host# set interface ge-0/0/0.1 immediate-leave
Verify the configuration by checking the Immediate Leave field in the output of the show igmp interface command.

Specifying Immediate-Leave Host Removal for IGMP

Related Topics