3Com Switch 4500 26-Port Configuration Manual page 156

154 C 8: IGMP S
HAPTER NOOPING
Figure 45 Multicast packet transmission when IGMP Snooping runs
Multicast router
Layer 2 Ethernet Switch
Switch 4500
Video stream
Multicast group member Non-multicast
group member
IGMP Snooping Terminology
Table 153 explains switching terminology relevant to IGMP Snooping.
Table 153 Switching Terminology relevant to IGMP Snooping
Term
Router Port
Multicast member port
MAC multicast group
Router port aging time
Multicast group member port
aging time
Maximum response time
The Switch 4500 runs IGMP Snooping to listen to the IGMP messages and map
the host and its ports to the corresponding multicast group address. To implement
IGMP Snooping, the switch processes different IGMP messages as shown in
Figure 46.
Internet / Intranet
Video stream
Video stream
Video stream
Non-multicast
group member
Meaning
The port of the switch, directly connected to the multicast
router.
The port connected to the multicast member. The multicast
member refers to a host that joined a multicast group.
The multicast group is identified with MAC multicast address
and maintained by the Switch 4500.
Time set on the router port aging timer. If the switch has not
received any IGMP general query messages before the timer
times out, it is no longer considered a router port.
When a port joins an IP multicast group, the aging timer of
the port will begin timing. If the switch has not received any
IGMP report messages before the timer times out, it
transmits IGMP specific query message to the port.
When the switch transmits IGMP specific query message to
the multicast member port, the Switch 4500 starts a
response timer, which times before the response to the
query. If the switch has not received any IGMP report
message before the timer times out, it will remove the port
from the multicast member ports
Video stream
VOD Server