igmp max-response-time

Function

The igmp max-response-time command sets the maximum response time for IGMP General Query messages on an interface.

The undo igmp max-response-time command restores the default maximum response time for General IGMP Query messages.

By default, the maximum response time for IGMP General Query messages is 10s on an interface.

Format

igmp max-response-time interval

undo igmp max-response-time

Parameters

Parameter	Description	Value
interval	Specifies the maximum response time for IGMP General Query messages.	The value is an integer that ranges from 1 to 25, in seconds.

Views

GE interface view, XGE interface view, MultiGE interface view, 25GE interface view, 40GE interface view, 100GE interface view, Eth-Trunk interface view, GE sub-interface view, XGE sub-interface view, MultiGE sub-interface view, 25GE sub-interface view, 40GE sub-interface view, 100GE sub-interface view, Eth-Trunk sub-interface view, VLANIF interface view, loopback interface view

Default Level

2: Configuration level

Usage Guidelines

Usage Scenario

If hosts send IGMP Report messages immediately after they receive IGMP General Query messages, the querier on a shared network segment may receive a large number of Report messages sent from many hosts at the same time. This may cause congestion on the network.

To avoid such situations, IGMPv2 and IGMPv3 messages specify the maximum response time for IGMP General Query messages. When a host running IGMPv2 or IGMPv3 receives an IGMP General Query message, it starts a timer for the group it wants to join. The timer length is a random value between 0 and the maximum response time. When the timer times out, the host sends a Report message.

The maximum response time specifies the deadline for the host to send a Report message. An appropriate maximum response time allows hosts to respond to Query messages quickly and prevents hosts from sending Report messages at the same time.

Prerequisites

IP multicast routing has been enabled using the multicast routing-enable command.

Precautions

This command is valid only for IGMPv2 and IGMPv3.
A shorter response time allows a multicast device to obtain multicast group member information more quickly, but consumes more bandwidth and system resources.
The igmp max-response-time command has the same function as the max-response-time command used in the IGMP view. The configuration in the IGMP view takes effect for all interfaces, whereas the configuration in the interface view takes effect only for the specified interface. The configuration in the interface view takes precedence over the configuration in the IGMP view. The configuration in the IGMP view is used only when no configuration is performed in the interface view.

Example

# Set the maximum response time for IGMP General Query messages to 8 seconds on VLANIF100.

<HUAWEI> system-view
[HUAWEI] multicast routing-enable
[HUAWEI] interface vlanif 100
[HUAWEI-Vlanif100] igmp max-response-time 8

# Set the maximum response time for IGMP General Query messages to 8 seconds on GE0/0/1.

<HUAWEI> system-view
[HUAWEI] multicast routing-enable
[HUAWEI] interface gigabitethernet 0/0/1
[HUAWEI-GigabitEthernet0/0/1] undo portswitch
[HUAWEI-GigabitEthernet0/0/1] igmp max-response-time 8