igmp-snooping prompt-leave

Function

The igmp-snooping prompt-leave command enables the fast leave function in a VLAN so that member ports in the VLAN can fast leave multicast groups.

The undo igmp-snooping prompt-leave command disables the fast leave function in a VLAN.

By default, the fast leave function is disabled in a VLAN.

Format

igmp-snooping prompt-leave [ group-policy acl-number ]

undo igmp-snooping prompt-leave

Parameters

Parameter	Description	Value
group-policy	Specifies a multicast group policy that allows member ports to fast leave some multicast groups. Before using this parameter, create an ACL and configure filter rules in the ACL.	-
acl-number	Specifies the number of an ACL that defines a range of multicast groups. A basic or advanced ACL can be used.	The value is an integer that ranges from 2000 to 3999.

Views

VLAN view

Default Level

2: Configuration level

Usage Guidelines

Usage Scenario

The fast leave function enables the switch to delete the multicast forwarding entry of a multicast group from an interface immediately after the interface receives an IGMP Leave message for the group. This function saves bandwidth and system resources because the switch does not need to wait until the aging timer of the interface expires.

Prerequisites

IGMP snooping has been enabled globally using the igmp-snooping enable (system view) command.

Precautions

When an interface has more than one receiver connected, enabling the fast leave function interrupts multicast traffic of the other receivers in the multicast group. It is recommended that you enable this function only on interfaces with one receiver.

The configuration takes effect only when all the following conditions are met:

IGMP snooping is enabled in the VLAN using the igmp-snooping enable (VLAN view) command.
IGMPv2 or IGMPv3 messages can be processed in the VLAN.
If you do not specify group-policy when configuring the fast leave function, this function takes effect for all groups. To specify a group policy in the command, create an ACL and configure rules for the ACL before running the command.

Example

# Allow member ports in VLAN 2 to fast leave all groups.

<HUAWEI> system-view
[HUAWEI] igmp-snooping enable
[HUAWEI] vlan 2
[HUAWEI-vlan2] igmp-snooping enable
[HUAWEI-vlan2] igmp-snooping prompt-leave

# Allow member ports in VLAN 3 to fast leave group 225.1.1.123.

<HUAWEI> system-view
[HUAWEI] igmp-snooping enable
[HUAWEI] acl number 2000
[HUAWEI-acl-basic-2000] rule permit source 225.1.1.123 0
[HUAWEI-acl-basic-2000] quit
[HUAWEI] vlan 3
[HUAWEI-vlan3] igmp-snooping enable
[HUAWEI-vlan3] igmp-snooping prompt-leave group-policy 2000

# Prevent member ports in VLAN 3 from fast leaving group 225.1.1.123.

<HUAWEI> system-view
[HUAWEI] igmp-snooping enable
[HUAWEI] acl number 2000
[HUAWEI-acl-basic-2000] rule deny source 225.1.1.123 0
[HUAWEI-acl-basic-2000] quit
[HUAWEI] vlan 3
[HUAWEI-vlan3] igmp-snooping enable
[HUAWEI-vlan3] igmp-snooping prompt-leave group-policy 2000