Specifications

CLI Management Guide
TigerAccess™ EE
264 SMC7824M/VSW
Switch B Switch C
BPDU Flow
ROOT
Switch D
1. New link created
2. Transmit BPDU
at listening state
3. Block to
prevent loop
Switch A
Fig. 8.17 Network Convergence of 802.1d
This is very epochal way of preventing a loop. The matter is that communication is dis-
connected during two times of BPDU Forward-delay till a port connected to switch D and
SWITCH C is blocked. Then, right after the connection, it is possible to transmit BPDU al-
though packet cannot be transmitted between switch A and root.
Switch B Switch C
ROOT
Switch D
1. New link created
2. Negotiate between
Switch A and ROOT
(Traffic Blocking)
Switch A
Fig. 8.18 Network Convergence of 802.1w (1)
SWITCH A negotiates with root through BPDU. To make link between SWITCH A and root,
port state of non-edge designated port of SWITCH is changed to blocking. Although
SWITCH A is connected to root, loop will not be created because SWITCH A is blocked to