Which switching concept helps prevent loops in a switching environment?

• A. Address learning
• B. Forward Filter Decision
• C. Loop avoidance
• D. Collision detection

Answer: (C)

Loop avoidance is about stopping frames from circulating endlessly when multiple paths exist in a switching network. In Ethernet, having several active paths between devices can create a loop where broadcasts and even unicast frames keep looping, leading to broadcast storms and network degradation. Loop avoidance techniques prevent this by creating a loop-free topology—typically by automatically blocking some redundant links while keeping others active. The classic example is Spanning Tree Protocol, which elects a root bridge and blocks certain ports to ensure there is a single active path between any two devices; if a link fails, the protocol can re-enable a previously blocked path to restore connectivity.

Address learning helps switches map MAC addresses to ports to forward frames efficiently, but it doesn’t by itself stop loops. Collision detection is a feature of older shared-medium networks and isn’t how modern switches prevent loops. Forward Filter Decision isn’t a standard term for loop prevention and doesn’t address the loop issue directly.