Multimedia Traffic Control with IP Multicast (IGMP) 
IGMP General Operation and Features 
Enabling IGMP allows detection of IGMP queries and report packets in order 
to manage IP multicast traffic through the switch. If no other querier is 
detected, the switch will then also function as the querier. (If you need to 
disable the querier feature, you can do so through the IGMP configuration 
MIB. Refer to “Changing the Querier Configuration Setting” on page 
4-10.) 
Note  IGMP configuration on the Series 5300XL switches 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 4-11. 
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