Where should loop guard the implemented in a campus network design?

The correct answer is D. Alternate, backup and root ports. Loop Guard should be enabled on alternate, backup, and root ports - all non-designated ports that are expected to receive BPDUs. If BPDUs stop arriving on these ports (e.g., due to a unidirectional link failure), standard STP would move them to a forwarding state, potentially…

Advanced Enterprise Campus Networks

Question

Options

APorts configured with port fast
BAlternate ports only
CPorts configured with root guard
DAlternate, backup and root ports

How the community answered

(38 responses)

B
3% (1)
C
3% (1)
D
95% (36)

Explanation

Loop Guard should be enabled on alternate, backup, and root ports - all non-designated ports that are expected to receive BPDUs. If BPDUs stop arriving on these ports (e.g., due to a unidirectional link failure), standard STP would move them to a forwarding state, potentially creating a loop. Loop Guard prevents this by placing the port into a 'loop-inconsistent' blocking state instead. It should NOT be placed on PortFast ports (which are access edge ports, not topology ports) or ports with Root Guard (which is a conflicting guard mechanism).

Topics

#loop guard#STP port roles#campus STP design#alternate ports

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