Configuring bpdu-timeout-action enables which protection mechanism?

A.
root protection

B.
BPDU protection

C.
loop protection

D.
RSTP protection

Explanation:
A loop-free network in spanning-tree topologies is supported through the exchange of a special type of frame called bridge protocol data unit (BPDU). Peer STP applications running on the switch interfaces use BPDUs to communicate. Ultimately, the exchange of BPDUs determines which interfaces block traffic (preventing loops) and which interfaces become root ports and forward traffic.

A blocking interface can transition to the forwarding state in error if the interface stops receiving BPDUs from its designated port on the segment. such transition error can occur when there is hardware error on the switch or software configuration error between the switch and its neighbor. When this happens, a loop opens up in the spanning tree and cause broadcast storm.

In the case of EX8200 switches if both routing engines are halted, line cards on the switch stops forwarding control packets such as spanning tree BPDU’s but remains active for 10+ minutes. During such condition the interfaces of EX8200 which are connected to another switch goes into forwarding state from blocking state on non receipt of the BPDUs. Such transition of the port state from blocking to forwarding can cause network loop and then broadcast storm.

To prevent such network loop condition, it is safer to configure bpdu timeout action on the interfaces connected to another STP capable switch as follows:

#set protocol rstp interface <name of the interface> bpdu-timeout-action block
In the case loop is detected on the interface configured for bpdu-timeout-action block, the interface remains in block state with role disabled (loop-incosistent)