Installation manual

3-247
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Enabling IGMP Immediate Leave
The switch can be configured to immediately delete a member port of a multicast service
if a leave packet is received at that port and the immediate-leave function is enabled for
the parent VLAN. This allows the switch to remove a port from the multicast forwarding
table without first having to send an IGMP group-specific query to that interface.
Command Usage
• If immediate leave is not used, a multicast router (or querier) will send a group-specific
query message when an IGMPv2/v3 group leave message is received. The router/
querier stops forwarding traffic for that group only if no 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 3-245).
• If immediate leave is enabled, the switch assumes that only one host is connected to the
interface. Therefore, immediate leave should only be enabled on an interface if it is
connected to only one IGMP-enabled device, either a service host or a neighbor running
IGMP snooping.
• Immediate leave is only effective if IGMP snooping is enabled, and IGMPv2 or IGMPv3
snooping is used.
• Immediate leave does not apply to a port if the switch has learned that a multicast router
is attached to it.
• Immediate leave can improve bandwidth usage for a network which frequently
experiences many IGMP host add and leave requests.
Command Attributes
• VLAN ID – VLAN Identifier. (Range: 1-4094).
• Immediate Leave – Sets the status for immediate leave on the specified VLAN.
(Default: Disabled)
Web – Click IGMP Snooping, IGMP Immediate Leave. Select the VLAN interface to
configure, set the status for immediate leave, and click Apply.
Figure 3-137 IGMP Immediate Leave