C
ONFIGURING
 
THE
 S
WITCH
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Command Usage
• IGMP Snooping – This switch can passively snoop on IGMP 
Query and Report packets transferred between IP multicast 
routers/switches and IP multicast host groups to identify the IP 
multicast group members. It simply monitors the IGMP packets 
passing through it, picks out the group registration information, 
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 
members. It then propagates the service requests on to any 
adjacent multicast switch/router to ensure that it will continue 
to receive the multicast service. 
Note: Multicast routers use this information, along with a 
multicast routing protocol such as DVMRP or PIM, to 
support IP multicasting across the Internet.
Command Attributes
• IGMP Status — When enabled, the switch will monitor 
network traffic to determine which hosts want to receive 
multicast traffic. This is also referred to as IGMP Snooping. 
(Default: Disabled)
• Act as IGMP Querier — When enabled, the switch can serve 
as the Querier, which is responsible for asking hosts if they 
want to receive multicast traffic. (Default: Disabled)
b_mgmt.book  Page 114  Tuesday, July 8, 2003  5:24 PM