How often are BPDUs sent from a layer 2 device?

BPDUs, or Bridge Protocol Data Units, are fundamental in the operation of the Spanning Tree Protocol (STP), which is used to prevent loops in a Layer 2 network. These packets are transmitted by switches to share information about the network topology and to ensure that all devices can make cohesive decisions regarding the forwarding of packets.

Correctly, BPDUs are sent every 2 seconds by default. This regular transmission helps maintain an updated and consistent understanding of the network topology among the switches. Each switch sends out BPDUs periodically to inform other devices of its presence and the state of its ports. This rapid communication is crucial for timely detection of any topology changes so that the network can adapt, avoiding loops and ensuring efficient path selection for data traffic.

The other answer choices indicate either much longer or no transmission intervals, which would lead to outdated or inconsistent network state information. If BPDUs were sent every 10 minutes or every 30 seconds, the switches would not be able to react quickly to topology changes, increasing the risk of loops occurring and leading to inefficiencies within the network. The choice of 'never' is counterintuitive, as the functioning of STP relies on the periodic sending of BPDUs to maintain network stability