BFD can implement millisecond-level link status detection.

Understanding BFD (Bidirectional Forwarding Detection)

BFDis ahigh-speed fault detection protocolused to monitor link failures inmilliseconds.

It operates atLayer 2 (Data Link Layer) and Layer 3 (Network Layer)to providefast convergence.

Why Can BFD Detect Failures in Milliseconds?

Useslightweight control packetsthat are exchanged between routers.

Works withOSPF, IS-IS, BGP, and MPLSto trigger fast convergence.

Detection time = (Transmit Interval) × (Detect Multiplier)

Example: If the interval is3msand the multiplier is3, failure detection takes9ms.

Why is the Answer TRUE?

✅BFD achieves millisecond-level detectionby sending rapid probe packets.

✅Used in high-availability networkswhere link failures must be detected inreal-time.

Real-World Application

Service Provider Networks:BFD improves network resilience by detecting link failuresfaster than traditional routing timers.

Enterprise WANs:Used inSD-WANsto switch paths dynamically.

MPLS Fast Reroute (FRR):Works withMPLS Traffic Engineeringfor near-instantaneous failover.

✅Reference:Huawei HCIE-Datacom Guide – BFD for Fast Link Failure Detection