Configuring the Querier Function

The querier function enables a device to send Query messages for its upstream device and respond to Join/Leave messages sent from downstream devices.

Context

A Layer 3 multicast device on a multicast network running IGMP acts as an IGMP querier, sending IGMP Query messages to create and maintain multicast forwarding entries for normal multicast data forwarding.

The querier function, however, cannot be implemented on a Layer 3 device in either of the following situations:

IGMP messages sent from the Layer 3 device cannot reach a downstream Layer 2 device.
Multicast forwarding entries on the Layer 3 device are statically configured and do not need to be dynamically learned.

In this case, the IGMP querier function of the upstream device cannot be implemented on the network.

To solve these issues, configure the querier function on the Layer 2 device so that it can create and maintain multicast forwarding entries at the data link layer, ensuring normal multicast data forwarding. The querier parameters can be set as required.

Procedure

Run system-view
The system view is displayed.
Perform either of the following operations to select VLAN or VPLS networking:
- Run the vlan vlan-id command to enter the VLAN view.
- Run the vsi vsi-name [ static ] command to enter the VSI view.
Run igmp-snooping enable
IGMP snooping is enabled for the VLAN or VSI.
Run igmp-snooping querier enable
The querier function is enabled.

By default, the querier function is disabled.
Run igmp-snooping querier-election
One of these devices is elected as the querier to send Query messages to user hosts.

By default, no device is enabled with the querier function.

If the querier function is enabled on multiple devices in the VSI or VLAN, one of these devices must be elected as the querier to send Query messages to user hosts.
(Optional) Set querier parameters.

An IGMPv1 host does not send a Leave message when leaving a multicast group. Therefore, the igmp-snooping lastmember-queryinterval command is valid only when IGMPv2 messages can be processed in the VLAN or VSI.
- Run igmp-snooping query-interval query-interval
  
  The interval at which a querier sends general query messages is set.
  
  By default, a querier sends general query messages at an interval of 60s.
  
  The default interval value in this command is 60s, which is different than the default value (125s) defined by the relevant standard. A Huawei querier and a non-Huawei querier must send IGMP general query messages at the same interval.
- Run igmp-snooping robust-count robust-count
  
  The number of times a group-specific query message is sent is set.
  
  By default, a group-specific query message is sent twice.
- Run igmp-snooping max-response-time max-response-time
  
  The maximum time for a downstream host to respond to a querier is set.
  
  By default, the maximum time for a downstream host to respond to a querier is 10s.
  
  The maximum response time must be shorter than the interval at which general query messages are sent.
- Run igmp-snooping lastmember-queryinterval lastmember-queryinterval
  
  The interval at which a querier sends group-specific query messages or source/group-specific query messages is set.
  
  By default, a querier sends group-specific query messages or source/group-specific query messages every 1s.
Run commit
The configuration is committed.