Configuring An Igmp Snooping Querier; Configuration Prerequisites; Enabling Igmp Snooping Querier; Configuring Parameters For Igmp Queries And Responses - HP MSR2003 Configuration Manual

Configuring an IGMP snooping querier

This section describes how to configure an IGMP snooping querier.

Configuration prerequisites

Before you configure an IGMP snooping querier, complete the following tasks:
Enable IGMP snooping for the VLAN.
•
Determine the interval for sending IGMP general queries.
•
• Determine the IGMP last member query interval.
Determine the maximum response time for IGMP general queries.
•

Enabling IGMP snooping querier

A Layer 2 multicast device does not support IGMP, and by default it cannot send queries. To ensure
multicast data forwarding at the data link layer on a network without Layer 3 multicast devices, you can
configure the Layer 2 device as an IGMP snooping querier. In this way, the Layer 2 device sends IGMP
queries, and establishes and maintains multicast forwarding entries.
Do not configure an IGMP snooping querier in a multicast network that runs IGMP. An IGMP snooping
querier does not take part in IGMP querier elections. However, it might affect IGMP querier elections if
it sends IGMP general queries with a low source IP address.
To enable IGMP snooping querier:
Step
1. Enter system view.
2. Enter VLAN view.
3. Enable
querier.

Configuring parameters for IGMP queries and responses

CAUTION:
Make sure the interval for sending IGMP general queries is larger than the maximum response time for
IGMP general queries. Otherwise, multicast group members might be deleted by mistake.
You can modify the IGMP general query interval based on the actual condition of the network.
A multicast listening host starts a timer for each multicast group that it has joined when it receives an
IGMP query (general query or group-specific query). This timer is initialized to a random value in the
range of 0 to the maximum response time advertised in the IGMP query message. When the timer value
decreases to 0, the host sends an IGMP report to the multicast group.
To speed up the response of hosts to IGMP queries and to avoid simultaneous timer expirations from
causing IGMP report traffic bursts, you must correctly set the maximum response time.
The maximum response time for IGMP general queries is set by the max-response-time command.
•
• The maximum response time for IGMP group-specific queries equals the IGMP last member query
interval.
Command
system-view
vlan vlan-id
IGMP snooping
igmp-snooping querier
23
Remarks
N/A
N/A
By default, no IGMP snooping
querier is configured.