STP BPDU Port ID Field

D

STP (Spanning Tree Protocol) is a network protocol used to prevent network loops in Ethernet networks. The protocol works by creating a loop-free topology among the switches in the network. The protocol creates a tree-like structure, where one of the switches is elected as the root bridge, and all the other switches in the network have a path to the root bridge.

When switches exchange information with each other about their topology, they use a special frame called a Bridge Protocol Data Unit (BPDU). The BPDU contains information about the switch that sent it, such as its bridge priority and bridge address, and information about the port that the BPDU is being sent from, such as its port priority and port address.

The Port ID field in an STP BPDU contains information about the port that the BPDU is being sent from. Specifically, it contains the port priority and port address of the port. The port priority is used to determine which port on a switch should be used as the root port or designated port. The port address is used to identify the port on the switch.

Therefore, the correct answer to the question is D. The Port ID field in an STP BPDU contains the port priority and port address.