Configuring IGMP Parameters
You can configure the switch to forward multicast traffic intelligently. Based on
the IGMP query and report messages, the switch forwards traffic only to the
ports that request multicast traffic. This prevents the switch from broadcasting
the traffic to all ports and possibly disrupting network performance.
Command Usage
> IGMP Snooping – This switch can passively snoop on IGMP Query and
Report packets transferred between IP multicast routers/switches and IP multi-
cast host groups to identify the IP multicast group members. It simply monitors
the IGMP packets passing through it, picks out the group registration informa-
tion, and configures multicast filters accordingly.
> IGMP Query – A router, or multicast-enabled switch, can periodically ask their
hosts if they want to receive multicast traffic. If there is more than one
router/switch on the LAN performing IP multicasting, one of these devices is
elected “querier” and assumes the role of querying the LAN for group mem-
bers. It then propagates the service requests on to any adjacent multicast
switch/router to ensure that it will continue to receive the multicast service.
Multicast routers use this information, along with a multicast routing protocol such as
DVMRP, to support IP multicasting across the Internet.
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