Operation Manual - STP
Quidway S6500 Series Ethernet Switches Chapter 1 MSTP Region-configuration
Huawei Technologies Proprietary
1-5
Switch A
Switch C
Switch B
CP2
BP2
CP1
BP1
AP2AP1
LAN
Figure 1-3 Designated bridge and designated port
For a switch, the designated bridge is a switch in charge of forwarding BPDU to the
local switch via a port called the designated port accordingly. For a LAN, the designated
bridge is a switch that in charge of forwarding BPDU to the network segment via a port
called the designated port accordingly. As illustrated in the figure1-1, Switch A forwards
data to Switch B via the port AP1. So to Switch B, the designated bridge is Switch A and
the designated port is AP1. Also in the figure above, Switch B and Switch C are
connected to the LAN and Switch B forwards BPDU to LAN. So the designated bridge
of LAN is Switch B and the designated port is BP2.
 Note:
AP1, AP2, BP1, BP2, CP1 and CP2 respectively delegate the ports of Switch A, Switch
B and Switch C.
z The specific calculation process of STP algorithm.
The following example illustrates the calculation process of STP.
The figure1-2 below illustrates the network.
Switch A
with priority 0
Switch C
with priority 2
Switch B
with priority 1
CP2
BP2
CP1
BP1
AP2
AP1
4
10
5
Figure 1-4 Ethernet switch networking