igmp-snooping query-interval

Function

The igmp-snooping query-interval command sets the general query interval in a VLAN, that is, the interval at which IGMP General Query messages are sent in the VLAN.

The undo igmp-snooping query-interval command restores the default general query interval in a VLAN.

By default, the general query interval is 125 seconds.

Format

igmp-snooping query-interval query-interval

undo igmp-snooping query-interval

Parameters

Parameter	Description	Value
query-interval	Specifies the interval at which IGMP General Query messages are sent.	The value is an integer that ranges from 1 to 65535, in seconds.

Views

VLAN view

Default Level

2: Configuration level

Usage Guidelines

Usage Scenario

By setting the general query interval, you can:

Configure the switch to send IGMP General Query messages at intervals to maintain memberships of interfaces. When a shorter interval is configured, the switch is more sensitive to multicast membership changes, but more bandwidth and system resources are consumed.
Change the aging time of multicast member ports.

When receiving an IGMP Report message from a host, the switch starts the aging timer for the multicast member port. The aging time is calculated using the following formula: Aging time = IGMP robustness variable x General query interval + Maximum response time for General Query messages. The igmp-snooping query-interval command sets the general query interval. The general query count is set by the igmp-snooping robust-count command, and the maximum response time for General Query messages is set by the igmp-snooping max-response-time command.

The general query interval affects the aging time of group member ports. A shorter general query interval results in a shorter aging time of group member ports and therefore a faster update speed of Layer 2 multicast entries. However, when there are many downstream users connected to a device, a short general query interval can cause flapping of multicast entries, leading to a high CPU usage on the device. Therefore, the default general query interval is recommended. If you need to change the interval to suit service deployment, set the value according to the following table.

Number of IGMP Messages Sent from Downstream Users Within Maximum Response Time	Minimum General Query Interval Reference Value (Seconds)
1 to 1024	10
1024 to 2048	20
2048 to 5120	40

The default general query interval defined in RFC documents is 125 seconds, but some vendors define their own default general query intervals. It is recommended that all devices on a multicast network use the same general query intervals (including IGMP and IGMP snooping general query intervals). On Huawei fixed switches, the default value of the IGMP general query interval is 60 seconds, and the default value of the IGMP snooping general query interval is 125 seconds.

Prerequisites

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

Precautions

The configuration takes effect only after you run the igmp-snooping enable (VLAN view) command to enable IGMP snooping in the VLAN.
The interval at which General Query messages are sent must be longer than the maximum response time for General Query messages. Otherwise, the switch will delete multicast memberships that should not be deleted.

Example

# Set the general query interval in VLAN 3 to 100 seconds.

<HUAWEI> system-view
[HUAWEI] igmp-snooping enable
[HUAWEI] vlan 3
[HUAWEI-vlan3] igmp-snooping enable
[HUAWEI-vlan3] igmp-snooping query-interval 100