Huawei Quidway S3000 Series Operation Manual page 30

Operation Manual - STP
Quidway S3000 Series Ethernet Switches
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 packets to LAN. So the designated
switch 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.
The specific calculation process of STP algorithm.
The following example illustrates the calculation process of STP.
The Figure2-4
Switch B
with priority 1
Figure2-4 Ethernet switch networking
To facilitate the descriptions, only the first four parts of the configuration BPDU are
described in the example. They are root ID (expressed as Ethernet switch priority), path
cost to the root, designated switch ID (expressed as Ethernet switch priority) and the
designated port ID (expressed as the port number). As illustrated in the figure above,
the priorities of Switch A, B and C are 0, 1 and 2 and the path costs of their links are 5,
10 and 4 respectively.
9) Initial state
When initialized, each port of the switches will generate the configuration BPDU taking
itself as the root with a root path cost as 0, designated switch IDs as their own switch
IDs and the designated ports as their ports.
Switch A:
Configuration BPDU of AP1: {0, 0, 0, AP1}
Configuration BPDU of AP2: {0, 0, 0, AP2}
below illustrates the network.
Switch A
with priority 0
AP1
AP2
5
10
BP1
BP2
4
CP2
Switch C
with priority 2
CP1
2-6
Chapter 1 RSTP Configuration