H3C Technologies H3C S7500E Series Switches - Manual (Page 36)

2-4
Aging timers for dynamic ports in IGMP Snooping and related messages and actions
Table 2-1 Aging timers for dynamic ports in IGMP snooping and related messages and actions
Timer Description
Message before
expiry
Action after expiry
Dynamic router port
aging timer
For each dynamic
router port, the switch
sets a timer initialized
to the dynamic router
port aging time.
IGMP general query of
which the source
address is not 0.0.0.0
or PIM hello
The switch removes
this port from its router
port list.
Dynamic member port
aging timer
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.
IGMP membership
report
The switch removes
this port from the IGMP
snooping forwarding
table.
The port aging mechanism of IGMP snooping works only for dynamic ports; a static port will
never age out.
How IGMP Snooping Works
A switch running IGMP snooping performs different actions when it receives different IGMP
messages, as follows:
The description about adding or deleting a port in this section is only for a dynamic port. Static
ports can be added or deleted only through the corresponding configurations. For details, see
Configuring Static Ports .
When receiving a general query
The IGMP querier periodically sends IGMP general queries to all hosts and routers (224.0.0.1)
on the local subnet to find out whether active multicast group members exist on the subnet.
Upon receiving an IGMP general query, the switch forwards it through all ports in the VLAN
except the receiving port and performs the following to the receiving port: