H3C S3100-52P Operation Manual page 247

Operation Manual – MSTP
H3C S3100-52P Ethernet Switch
Classification
For a LAN
Figure 1-1
BP1 and BP2, and CP1 and CP2 are ports on Device A, Device B, and Device C
respectively.
If Device A forwards BPDUs to Device B through AP1, the designated bridge for
Device B is Device A, and the designated port is the port AP1 on Device A.
Two devices are connected to the LAN: Device B and Device C. If Device B
forwards BPDUs to the LAN, the designated bridge for the LAN is Device B, and
the designated port is the port BP2 on Device B.
Figure 1-1 A schematic diagram of designated bridges and designated ports
Note:
All the ports on the root bridge are designated ports.
4) Path cost
Path cost is a value used for measuring link capacity. By comparing the path costs of
different links, STP selects the most robust links and blocks the other links to prune the
network into a tree.
Designated bridge
A designated bridge is a device
responsible for forwarding
BPDUs to this LAN segment.
shows designated bridges and designated ports. In the figure, AP1 and AP2,
1-3
Chapter 1 MSTP Configuration
Designated port
The port through which
the designated bridge
forwards BPDUs to this
LAN segment