ip igmp snooping fastleave

Syntax

ip igmp snooping fastleave <PORT-LIST>

no ip igmp snooping fastleave <PORT-LIST>

Description

Enables the switch to immediately remove the IGMP client from its IGMP table and cease transmitting multicast traffic to the client.

The no form of this command disables fastleave on the specified ports.

Command context

config-vlan

Parameters

fastleave <PORT-LIST>

Specifies a list of one or more ports to be configured as fastleave ports. You can specify a single port, a comma-separated list of ports or a range of ports such as 1/1/1-1/1/3.

Authority

Administrators or local user group members with execution rights for this command.

Usage

IGMP fastleave is configured for ports on a per-VLAN basis. Upon receiving a Leave Group message, the querier sends an IGMP Group-Specific Query message out of the interface to ensure that no other receivers are connected to the interface. If receivers are directly attached to the switch, it is inefficient to send the membership query as the receiver wanting to leave is the only connected host.

When a fastleave enabled switch port is connected to a single host and receives a leave, the switch does not wait for the querier status update interval, but instead immediately removes the IGMP client from its IGMP table and ceases transmitting multicast traffic to the client. (If the switch detects multiple end nodes on the port, Fastleave does not activate regardless of whether one or more of these end nodes are IGMP clients.) This processing speeds up the overall leave process and also eliminates the CPU overhead of having to generate an IGMP Group-Specific Query message.

Examples

Configuring fastleave ports for the VLAN:

switch(config)# vlan 2
switch(config-vlan)# ip igmp snooping fastleave 1/1/1
switch(config-vlan)# ip igmp snooping fastleave 1/1/1-1/1/2
switch(config-vlan)# ip igmp snooping fastleave 1/1/1,1/1/2-1/1/3
switch(config-vlan)# no ip igmp snooping fastleave 1/1/1
switch(config-vlan)# no ip igmp snooping fastleave 1/1/1-1/1/2