H3C Technologies H3C WX3000E Series Wireless Switches - Manual (Page 12)

3
in Figure 3 , after the AP joins two ESSs, the access controller creates two virtual Layer 2 interfaces:
WLAN-DBSS 67:67 and WLAN-DBSS 68:66. The ESS corresponding to WLAN-DBSS 67:67
comprises a multicast receiver Client B, so WLAN-DBSS 67:67 is a member port.
Figure 3 Port roles on an IGMP snooping–enabled AC
Aging timers for dynamic ports in IGMP snooping
Timer Description Message before expiry Action after expiry
Dynamic router port
aging timer
For each dynamic router
port, the Layer 2 device
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 Layer 2 device
removes this port from its
router port list.
Dynamic member port
aging timer
When a port dynamically
joins a multicast group,
the Layer 2 device sets a
timer for the port, which
is initialized to the
dynamic member port
aging time.
IGMP membership
report.
The Layer 2 device
removes this port from the
IGMP snooping
forwarding table.
NOTE:
The port aging mechanism of IGMP snooping works only for dynamic ports. A static port never ages out.
How IGMP snooping works
An IGMP snooping–enabled Layer 2 device performs different actions when it receives different IGMP
messages.