IronPort Systems 4108GL - Manual (Page 354)

15-4
Multimedia Traffic Control with IP Multicast (IGMP)
General Operation and Features
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N o t e IGMP configuration on the Switch 4108GL operates at the VLAN context level.
If you are not using VLANs, then configure IGMP in VLAN 1 (the default VLAN)
context.
IGMP Terms
■ IGMP Device: A switch or router running IGMP traffic control
features.
■ IGMP Host: An end-node device running an IGMP (multipoint, or
multicast communication) application.
■ Querier: A required IGMP device that facilitates the IGMP protocol
and traffic flow on a given LAN. This device tracks which ports are
connected to devices (IGMP clients) that belong to specific multicast
groups, and triggers updates of this information. A querier uses data
received from the queries to determine whether to forward or block
multicast traffic on specific ports. When the switch has an IP address
on a given VLAN, it automatically operates as a Querier for that VLAN
if it does not detect a multicast router or another switch functioning
as a Querier. When enabled (the default state), the switch’s querier
function eliminates the need for a multicast router. In most cases, HP
recommends that you leave this parameter in the default “enabled”
state even if you have a multicast router performing the querier
function in your multicast group. For more information, see “How
IGMP Operates” on page 15-11.