3Com MSR 50 Series Configuration Manual page 448

448 C 23: MSTP C
HAPTER ONFIGURATION
Initial state of each device
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The following table shows the initial state of each device.
Table 13 Initial state of each device
Device
Device A
Device B
Device C
Comparison process and result on each device
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The following table shows the comparison process and result on each device.
Table 14 Comparison process and result on each device
Device Comparison process
Device A Port AP1 receives the configuration BPDU of Device B {1,
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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,
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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.
Device A finds that both the root bridge and designated
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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.
Port name
AP1
AP2
BP1
BP2
CP1
CP2
BPDU of port
{0, 0, 0, AP1}
{0, 0, 0, AP2}
{1, 0, 1, BP1}
{1, 0, 1, BP2}
{2, 0, 2, CP1}
{2, 0, 2, CP2}
BPDU of port
after
comparison
AP1: {0, 0, 0,
AP1}
AP2: {0, 0, 0,
AP2}