M
ULTICAST
C
ONFIGURATION
2-101
•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 wan t to receive
multicast traffic. (Default: Disabled)
•IGMP Query Count — Sets the maximum number of queries issued
for which there has been no response before the switch takes action to
drop a client from the multicast group. (Default: 2, Range: 2 - 10)
•IGMP Query Interval — Sets the frequency (in seconds) at which the
switch sends IGMP host-query messages. (Default: 125,
Range: 60 - 125)
•IGMP Report Delay — Sets the time (in seconds) between receiving
an IGMP Report for an IP multicast address on a port before the
switch sends an IGMP Query out of that port and removes the entry
from its list. (Default: 10, Range: 5 - 30)
•Query Timeout — The time the switch waits after the previous
querier stops before it considers the router port (i.e., the interface