3Com 7757 Configuration Manual page 428

428 C 43: IGMP S
HAPTER
IGMP Snooping
Implementation
C
NOOPING ONFIGURATION
IGMP Snooping terminologies
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.
Router port aging timer, multicast member port aging timer, and query
■
response timer are described in Table 334.
Table 334 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 host, the
port corresponding to the host, and the corresponding multicast MAC address.
Figure 107 IGMP Snooping implementation
I G M P -enabl e d R out e r
I G M P S noopi n g - enabl e d S w i t c h
To implement Layer 2 multicast, the switch processes four different types of IGMP
messages it received, as shown in Table 335.
Packet normally
received before
Setting timeout
Aging time of the IGMP general query
router port message/PIM
message/DVMRP probe
message
Aging time of the IGMP message
multicast member
ports
Query response IGMP report message
timeout time
Source
I G MP M essage
I G M P M essage
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.