3Com 4800G Series, Configuration Manual

Page: 202 / 1246

202 C
HAPTER
23: MSTP C
ONFIGURATION
■
Comparison process and result on each device
The following table shows the comparison process and result on each device.
Table 40 Initial state of each device
Device Port name BPDU of port
Device A AP1 {0, 0, 0, AP1}
AP2 {0, 0, 0, AP2}
Device B BP1 {1, 0, 1, BP1}
BP2 {1, 0, 1, BP2}
Device C CP1 {2, 0, 2, CP1}
CP2 {2, 0, 2, CP2}
Table 41 Comparison process and result on each device
Device Comparison process
BPDU of port
after
comparison
Device A
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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 configuration
received message, and 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 discards the received configuration BPDU.
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Device A finds that both the root bridge and designated
bridge in the configuration BPDUs of all its ports are Device
A 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}