Siemens S223 - Manual (Page 207)

User Manual UMN:CLI
SURPASS hiD 6615 S223/S323 R1.5
A50010-Y3-C150-2-7619 207
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. 8.16 Convergence of 802.1d Network
This is very an epochal way of preventing a loop. The matter is that communication is
disconnected 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 although 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. 8.17 Network Convergence of 802.1w (1)