To what state will a port with STP Loop Guard enabled enter if it stops receiving BPDUs?

When Loop Guard is enabled on a switch port, its primary function is to prevent the creation of loops in the network by monitoring the reception of Bridge Protocol Data Units (BPDUs). If the port stops receiving BPDUs, Loop Guard will take action to avoid potential loops by transitioning that port into a specific state.

If a port with Loop Guard enabled fails to receive BPDUs, it will enter the "err-disabled" state. This state indicates that the port has been administratively disabled due to a network condition that could lead to a looping problem. In essence, Loop Guard enhances network stability and reliability by proactively shutting down the port to prevent issues that could arise from loops created due to the absence of BPDUs.

Being in an err-disabled state means that the port will not forward any traffic and requires manual intervention to recover, such as re-enabling the port once the underlying issue causing the lack of BPDUs has been resolved. This behavior differentiates Loop Guard from other mechanisms and reinforces its role in supporting the Spanning Tree Protocol (STP) by maintaining network topology integrity.