3Com 7757 Configuration Manual page 435

Configuring Suppression
on IGMP Host Report
Messages
However, a Layer 2 multicast switch does not support IGMP, and therefore does
have an IGMP querier to send general queries by default. By enabling IGMP
Snooping querier on a Layer 2 switch in a VLAN where multicast traffic needs to
be Layer-2 switched only and no multicast routers are present, the Layer 2 switch
will act as a querier to send IGMP general queries, thus allowing multicast
forwarding entries to be established and maintained at the data link layer.
You can also configure the source address and interval of general queries to be
sent from the IGMP Snooping querier.
Table 345 Configure IGMP Snooping querier
Operation
Enter system view
Enable IGMP Snooping
Enter VLAN view
Enable IGMP Snooping
Enable IGMP Snooping
querier
Configure the interval
between IGMP general
queries
Configure the source IP
address of IGMP general
queries
When a Layer 2 switch receives IGMP host report messages from a host in a
multicast group, the switch will forward the packets to the port of a Layer 3 switch
that is connected to it. In this way, a Layer 3 switch will receive the same IGMP
host report messages from multiple hosts in a multicast group when there are
multiple hosts in this multicast group.
When suppression on IGMP host report messages is enabled, in a query interval,
the Layer 2 switch will forward only the first IGMP host report message from a
multicast group to the Layer 3 switch, and drop the other IGMP host report
messages from the same multicast group.
Table 346 Configure suppression on IGMP host report messages
Operation
Enter system view
Configure suppression on
IGMP host report messages
IGMP Snooping Configuration
Command
system-view
igmp-snooping enable
vlan vlan-id
igmp-snooping enable
igmp-snooping querier
igmp-snooping
query-interval seconds
igmp-snooping
general-query
source-ip { current-interface
| ip-address }
Command
system-view
report-aggregation
435
Description
-
Required
By default, IGMP Snooping is
disabled.
-
Required
By default, IGMP Snooping is
disabled.
Required
By default, IGMP Snooping
querier is disabled.
Optional
By default, the interval
between IGMP general
queries is 60 seconds.
Optional
By default, the source IP
address of IGMP general
queries is 0.0.0.0.
Description
-
Required
By default, suppression on
IGMP host report messages is
disabled.