H3C Technologies H3C SecPath F1000-E - Manual (Page 198)

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Figure 2 Network diagram for the STP algorithm
• Initial state of each device
The following table shows the initial state of each device.
Table 4 Initial state of each device
Device Port name BPDU of port
AP1 {0, 0, 0, AP1}
Device A
AP2 {0, 0, 0, AP2}
BP1 {1, 0, 1, BP1}
Device B
BP2 {1, 0, 1, BP2}
CP1 {2, 0, 2, CP1}
Device C
CP2 {2, 0, 2, CP2}
• Comparison process and result on each device
The following table shows the comparison process and result on each device.
Table 5 Comparison process and result on each device
Device Comparison process
BPDU of port after
comparison
Device A
• Port AP1 receives the configuration BPDU of Device B {1, 0, 1,
BP1}. Device A finds that the configuration BPDU of the local
port {0, 0, 0, AP1} is superior to the received configuration
BPDU, and therefore discards the received configuration BPDU.
• Port AP2 receives the configuration BPDU of Device C {2, 0, 2,
CP1}. Device A finds that the BPDU of the local port {0, 0, 0,
AP2} is superior to the received configuration BPDU, and
therefore discards the received configuration BPDU.
• Device A finds that both the root bridge and designated bridge
in the configuration BPDUs of all its ports are itself, so it assumes
itself to be the root bridge. In this case, it does not make any
change to the configuration BPDU of each port, and starts
sending out configuration BPDUs periodically.
AP1: {0, 0, 0, AP1}
AP2: {0, 0, 0, AP2}