3Com WX3000 operation manual 5Comparison process and result on each device

Table 1-5Comparison process and result on each device

Device		Comparison process	BPDU of port after
			comparison
	z 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.
	z 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,	AP1: {0, 0, 0, AP1}
Device A		0, AP2} is superior to the received configuration BPDU, and
			AP2: {0, 0, 0, AP2}
		discards the received configuration BPDU.
	z	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.
	z Port BP1 receives the configuration BPDU of Device A {0, 0,
		0, AP1}. Device B finds that the received configuration BPDU
		is superior to the configuration BPDU of the local port {1, 0,1,
		BP1}, and updates the configuration BPDU of BP1.	BP1: {0, 0, 0, AP1}
	z Port BP2 receives the configuration BPDU of Device C {2, 0,
			BP2: {1, 0, 1, BP2}
		2, CP2}. Device B finds that the configuration BPDU of the
		local port {1, 0, 1, BP2} is superior to the received
		configuration BPDU, and discards the received configuration
		BPDU.
	z Device B compares the configuration BPDUs of all its ports,
Device B		and determines that the configuration BPDU of BP1 is the
		optimum configuration BPDU. Then, it uses BP1 as the root
		port, the configuration BPDUs of which will not be changed.	Root port BP1:
	z Based on the configuration BPDU of BP1 and the path cost of
			{0, 0, 0, AP1}
		the root port (5), Device B calculates a designated port
		configuration BPDU for BP2 {0, 5, 1, BP2}.	Designated port
	z	Device B compares the calculated configuration BPDU {0, 5,	BP2:
		1, BP2} with the configuration BPDU of BP2. If the calculated	{0, 5, 1, BP2}
		BPDU is superior, BP2 will act as the designated port, and
		the configuration BPDU on this port will be replaced with the
		calculated configuration BPDU, which will be sent out
		periodically.

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