Understanding BFD (Bidirectional Forwarding Detection)
* BFD is a high-speed fault detection protocol used to monitor link failures in milliseconds.
* It operates at Layer 2 (Data Link Layer) and Layer 3 (Network Layer) to provide fast convergence.
Why Can BFD Detect Failures in Milliseconds?
* Uses lightweight control packets that are exchanged between routers.
* Works with OSPF, IS-IS, BGP, and MPLS to trigger fast convergence.
* Detection time = (Transmit Interval) × (Detect Multiplier)
* Example: If the interval is 3ms and the multiplier is 3, failure detection takes 9ms.
Why is the Answer TRUE?
# BFD achieves millisecond-level detection by sending rapid probe packets.# Used in high-availability networks where link failures must be detected in real-time.
Real-World Application
* Service Provider Networks: BFD improves network resilience by detecting link failures faster than traditional routing timers.
* Enterprise WANs: Used in SD-WANs to switch paths dynamically.
* MPLS Fast Reroute (FRR): Works with MPLS Traffic Engineering for near-instantaneous failover.
# Reference: Huawei HCIE-Datacom Guide - BFD for Fast Link Failure Detection