mld-snooping robust-count

Function

The mld-snooping robust-count command configures the robustness variable. The robustness variable decides the number of group-specific Query messages to be sent by the querier.

The undo mld-snooping robust-count command restores the default robustness variable.

By default, the robustness variable is 2.

Format

mld-snooping robust-count robust-count

undo mld-snooping robust-count

Parameters

Parameter	Description	Value
robust-count robust-count	Sets the number of group-specific Query messages to be sent by the querier.	The value is an integer ranging from 2 to 5.

Parameter

Description

Value

robust-count robust-count

Sets the number of group-specific Query messages to be sent by the querier.

The value is an integer ranging from 2 to 5.

Views

VLAN view

Default Level

2: Configuration level

Task Name and Operations

Task Name	Operations
l2mc	write

Usage Guidelines

Usage Scenario

The mld-snooping robust-count command provides the following functions:

Adjusts the number of group-specific Query messages to be sent by a querier, preventing messages loss on a network.
When receiving an MLD Done message of a multicast group, the device sends group-specific Query messages for <robust-count> times to check whether there are any other members in this group. Run the mld-snooping lastmember-queryinterval command to set the interval at which group-specific Query messages are sent.
Changes the aging time of member interfaces.
After receiving a Report messages from a downstream host, the device sets the aging time of the member interface using the following formula: Member interface aging = Interval at which group-specific Query messages are sent x Number of group-specific Query messages to be sent. By default, the device sets the aging time to 2s. Run the mld-snooping robust-count command to set the number of group-specific Query messages to be sent, and run the mld-snooping lastmember-queryinterval command to set the interval at which group-specific Query messages are sent.
If the querier receives a Report message for the multicast group from another host within the robust-count x lastmember-queryinterval period, it continues to maintain the member interface information for the group. If the querier does not receive a Report message for the multicast group within this period, the querier considers that there is no member of the group on the network segment, and does not maintain the member interface information for the group.

Prerequisites

MLD snooping has been enabled using the mld-snooping enable command.

Configuration Impact

If the mld-snooping robust-count command is run more than once in the same view, the latest configuration overwrites the previous one.

Precautions

To use the mld-snooping robust-count configuration as a factor of adjusting the member interface aging time, set the same number of group-specific Query messages to be sent as that specified on its upstream device. Otherwise, multicast data transmission will be interrupted between the Layer 2 and Layer 3 devices.

The

mld-snooping robust-count command fails to be run in a VLAN view in any of the following conditions:

The VLAN is bound to a VSI.
The
mld-snooping robust-count command fails to be run in a VSI view in the following condition:
The VSI is bound to a BD.

Example

# Configure the querier of VLAN 100 to send five group-specific Query messages.

<HUAWEI> system-view
[~HUAWEI] mld-snooping enable
[*HUAWEI] vlan 100
[*HUAWEI-vlan100] mld-snooping robust-count 5