3Com 4200G 12-Port Configuration Manual page 264

250 C 29: IGMP S
HAPTER
IGMP Snooping
Fundamentals
C
NOOPING ONFIGURATION
IGMP Snooping terminologies
Before going on, we first describe the following terms involved in IGMP Snooping:
Router port: the switch port directly connected to the multicast router.
■
Multicast member port: a switch port connected to a multicast group member (a
■
host in a multicast group).
MAC multicast group: a multicast group identified by a MAC multicast address
■
and maintained by the switch.
The following three timers are closely associated with IGMP snooping.
Table 220 IGMP Snooping timers
Timer
Router port aging
timer
Multicast member
port aging timer
Query response
timer
Layer 2 multicast with IGMP Snooping
The switch runs IGMP Snooping to listen to IGMP messages and map the hosts and
the ports that connect the hosts to the corresponding multicast group addresses.
Figure 80 IGMP Snooping implementation
IGMP-enabled router
IGMP Snooping-enabled
Message normally
received before
Setting timeout
Aging time of the IGMP general query
router port message
Aging time of the IGMP report message
multicast member
ports
Query response IGMP report message
timeout time
Ethernet switch
Timeout action on the
switch
Consider that this port is
not a router port any more.
Send an IGMP
group-specific query
message to the multicast
member port.
Remove the port from the
member port list of the
multicast group.
Internet
Internet
IGMP message
IGMP message