Ensure BPDUs are Always Received

C

Peer STP applications running on switch interfaces exchange a special type of frame called a bridge protocol data unit (BPDU). Switches communicate interface information using BPDUs to create a loop-free topology that ultimately determines the root bridge and which interfaces block or forward traffic in the spanning tree.

However, a root port elected through this process has the possibility of being wrongly elected. A user bridge application running on a PC can generate BPDUs, too, and interfere with root port election.

To prevent this from happening, enable root protection on interfaces that should not receive superior BPDUs from the root bridge and should not be elected as the root port.

The feature that would ensure BPDUs are always received from neighboring switches to indicate that the remote switch is still alive is BPDU Control (Option B).

The Spanning Tree Protocol (STP) is used to avoid network loops by blocking redundant paths in the network. STP relies on the exchange of Bridge Protocol Data Units (BPDUs) between switches to detect and react to changes in the network topology. When a switch stops receiving BPDUs from a neighboring switch, it assumes that the neighbor switch has failed, and it starts recalculating the STP topology. However, if a switch does not receive BPDUs but still forwards data frames, it can create a loop, leading to network disruption.

BPDU Control is a feature that ensures that only designated ports are allowed to send or receive BPDUs. This feature provides a mechanism for protecting the network against loops caused by rogue devices or misconfigurations. With BPDU Control, if a port stops receiving BPDUs from a neighbor, the switch disables the port, preventing it from forwarding data frames and creating a loop. When the port starts receiving BPDUs again, it enables the port, allowing it to forward data frames.

Option A, Storm Control, is a feature that monitors the amount of broadcast, multicast, or unknown unicast traffic on a port and takes action if the traffic exceeds a predefined threshold. Storm Control can be used to prevent network congestion caused by excessive traffic, but it does not address the issue of lost BPDUs.

Option C, Root Protection, is a feature that prevents a switch from becoming the root bridge. This feature is used to protect the network against rogue switches that may try to take over the role of the root bridge, but it does not address the issue of lost BPDUs.

Option D, Loop Protection, is a feature that detects and disables ports that create a loop in the network. This feature is used to protect the network against misconfigurations or rogue devices that may cause loops, but it does not address the issue of lost BPDUs.

In summary, the feature that would ensure BPDUs are always received from neighboring switches to indicate that the remote switch is still alive is BPDU Control.