HP 1920 Gigabit Ethernet Switch Series User Manual page 194

Figure 174 STP network
As shown in Figure 174, the priority values of Device A, Device B, and Device C are 0, 1, and 2, and the
path costs of links among the three devices are 5, 10, and 4, respectively.
1. Device state initialization.
In Table 55, each configuration BPDU contains the following fields: root bridge ID, root path cost,
designated bridge ID, and designated port ID.
Table 55 Initial state of each device
Device
Device A
Device B
Device C
2. Configuration BPDUs comparison on each device.
In Table 56, each configuration BPDU contains the following fields: root bridge ID, root path cost,
designated bridge ID, and designated port ID.
Port name
AP1
AP2
BP1
BP2
CP1
CP2
181
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}