What are two valid BPDU types?

In the context of the Spanning Tree Protocol (STP), Bridge Protocol Data Units (BPDUs) are critical for the maintenance of the network topology and the detection of loops. The two primary types of BPDUs used within STP are the configuration BPDU and the topology change notification (TCN) BPDU.

The topology change notification is sent when there is a change in the network topology, such as when a switch is added or removed, or when a link goes up or down. This type of BPDU is essential for keeping all switches in the network informed about changes that might affect the Spanning Tree Protocol's operation. It triggers the recalculation of the STP to ensure that loops are avoided and the network remains stable.

On the other hand, configuration BPDUs are used by switches to communicate information about the spanning tree topology itself, such as the root bridge ID, path cost, and the age of the BPDU. They are sent regularly to maintain the topology and make sure all switches have a consistent view of the network.

While other options may suggest different types or implications of BPDUs, topology change notification is indeed one of the primary valid BPDU types recognized within the STP context, highlighting its role in