Huawei AR530 series Configuration Manual page 189

Huawei AR530&AR550 Series Industrial Switch Routers
Configuration Guide - Ethernet Switching
Example of STP Topology Calculation
After the root bridge, root ports, and designated ports are selected successfully, a tree topology
is set up on the entire network. The following example illustrates how STP calculation is
implemented.
Figure 6-8 STP networking and calculated topology
Port B1
DeviceB
Priority=1
As shown in
priorities 0, 1, and 2, respectively. The path costs between DeviceA and DeviceB, DeviceA and
DeviceC, and DeviceB and DeviceC are 5, 10, and 4, respectively.
1.
Issue 01 (2014-11-30)
Table 6-9 Selecting the optimal configuration BPDU
Ste Process
p
1 Each port compares the received configuration BPDU with its own configuration
BPDU:
l If the received configuration BPDU is inferior, the port discards the received
configuration BPDU and does retain its own configuration BPDU.
l If the received configuration BPDU is superior, the port replaces its own
configuration BPDU with the received one.
2 The device compares configuration BPDUs on all the ports and selects the optimal
one.
DeviceA
Priority=0
Port A1 Port A2
Path cost=4
Port C2
Port B2
Figure 6-8, DeviceA, DeviceB, and DeviceC are deployed on the network, with
Initial state of each device
Table 6-10 lists the initial state of each device.
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STP Topology
Calculation
Port C1
DeviceC
DeviceB
Priority=2
6 STP/RSTP Configuration
DeviceA
Root
Bridge
DeviceC
root port
designated port
blocked port
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