Specifications

Redundant Links
Rev. 9.41 Module 5 – 133
Using the port ID as a tie-breaker
In some cases, switches cannot use the bridge ID as the tie-breaker to determine the
lowest-cost path. In the network below, for example, Switch B and Switch C are
connected by two redundant links.
Because the STP neighbor for both paths has the same bridge ID, the switch uses the
port ID, which is another field in the BPDU, as the tie-breaker.
The port with the lowest port ID is the lowest-cost path.
For HP Internal Use Only