Enabling IGMP Immediate Leave
The switch can be configured to immediately delete a member po rt of a multic ast
service if a leave packet is received at that port and th e immedi ate-lea ve funct ion is
enabled for the parent VLAN. This allows the swit ch to remov e a port from the
multicast forwarding table without first having to send an IGMP group-s pecific qu ery
to that interface.
Command Usage
• If immediate leave is not used, a multicast router (or quer ier) will se nd a
group-specific query message when an IGMPv2/v3 group leave message is
received. The router/querier stops forwarding traffic for that group o nly if n o host
replies to the query within the specified timeout period. Note that the timeout period
is determined by the IGMP Query Report Delay (see “Configuring IGMP Snooping
and Query Parameters” on page 15-3).
If immediate leave is enabled, the switch assumes that only one host is connecte d
to the interface. Therefore, immediate leave should only be enabled on an interface
if it is connected to only one IGMP-enable d device , either a service ho st or a
neighbor running IGMP snooping.
Immediate leave is only effective if IGMP snooping is enabled, and IG MPv2 or
IGMPv3 snooping is used.
Immediate leave does not a pply to a port if the switch has learn ed t h at a m u lticast
router is attached to it.
Immediate leave can improve bandwidth usag e for a ne twork which frequentl y
experiences many IGMP host add and leave requests.
Command Attributes
VLAN ID – VLAN Identifier. (Range: 1-409 3).
Immediate Leave – Sets the status fo r immedia te leave on the specif ied VLAN.
(Default: Disabled)
Web
– Click IGMP Snooping, IGMP Immediate Leave. Select the VLAN inter fa ce to
configure, set the status for immediate leave, and click Apply.
Figure 15-1 IGMP Imm ed iate Le av e

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Layer 2 IGMP (Snooping and Query)

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