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Before performing the following configurations described in this chapter, you must enable multicast
routing and enable IGMP on the specific interfaces.
Configuring IGMP Version
Follow these steps to configure IGMP version:
To do... Use the command... Remarks
Enter system view
system-view
—
Enter interface view
interface interface-type
interface-number
—
Configure the IGMP version
igmp version { 1 | 2 }
Optional
The system default is IGMP
version 2.
IGMP versions cannot be switched to one another automatically. Therefore, all the interfaces on a
subnet must be configured to use the same IGMP version.
Configuring Options Related to IGMP Query Messages
IGMP general query
An IGMP router sends IGMP general query messages to the local subnet periodically, and multicast
receiver hosts send IGMP reports in response to IGMP queries. Thus the router learns which multicast
groups on the subnet have active members.
IGMP group-specific query
On a multi-access network, the query router (querier for short) maintains group memberships. After the
related features are configured, the IGMP querier sends a configurable number of IGMP group-specific
queries at a configurable interval when it receives an IGMP leave message from the hosts.
Suppose a host in a multicast group decides to leave the multicast group. The related procedure is as
follows:
z The host sends an IGMP leave message.
z When the IGMP querier receives the message, it sends robust-value IGMP group-specific query
messages at the interval of lastmember-queryinterval.
z If other hosts are interested in the group after receiving the IGMP group-specific query message
from the querier, they must send IGMP report messages within the maximum response time
specified in the query messages.
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