3Com S7906E Configuration Manual page 1190

Router port: A router port is a port on an Ethernet switch that leads the switch towards a Layer 3
multicast device (DR or IGMP querier). In the figure, GigabitEthernet 2/0/1 of Switch A and
GigabitEthernet 2/0/1 of Switch B are router ports. The switch registers all its local router ports in its
router port list.
Member port: A member port is a port on an Ethernet switch that leads the switch towards multicast
group members. In the figure, GigabitEthernet 2/0/2 and GigabitEthernet 2/0/3 of Switch A and
GigabitEthernet 2/0/2 of Switch B are member ports. The switch registers all the member ports on
the local device in its IGMP snooping forwarding table.
Whenever mentioned in this document, a router port is a port on the switch that leads the switch to
a Layer 3 multicast device, rather than a port on a router.
Unless otherwise specified, router/member ports mentioned in this document include static and
dynamic ports.
An IGMP-snooping-enabled switch deems that all its ports on which IGMP general queries with the
source IP address other than 0.0.0.0 or PIM hello messages are received are dynamic router ports.
For details about PIM hello messages, see PIM Configuration of the IP Multicast Volume.
Aging timers for dynamic ports in IGMP Snooping and related messages and actions
Table 1-1 Aging timers for dynamic ports in IGMP snooping and related messages and actions
Timer
Dynamic router port
aging timer
Dynamic member port
aging timer
The port aging mechanism of IGMP snooping works only for dynamic ports; a static port will never age
out.
Description
For each dynamic
router port, the switch
sets a timer initialized
to the dynamic router
port aging time.
When a port
dynamically joins a
multicast group, the
switch sets a timer for
the port, which is
initialized to the
dynamic member port
aging time.
1-3
Message before
expiry
IGMP general query of
which the source
address is not 0.0.0.0
or PIM hello
IGMP membership
report
Action after expiry
The switch removes
this port from its router
port list.
The switch removes
this port from the IGMP
snooping forwarding
table.