Company XYZ is running a redundant private WAN network using OSPF as the underlay protocol.

BFD (Bidirectional Forwarding Detection) provides rapid failure detection independent of OSPF’s native hello/dead timers.

BFD operates at subsecond intervals (as low as 50ms), detecting link failures almost immediately, allowing OSPF to react instantly upon failure detection.

BFD complements OSPF and significantly improves convergence time without compromising OSPF’s stability.

Why other options are incorrect:

A: STP is irrelevant for Layer 3 routing failures.

B: Fate sharing describes failure domains, not detection mechanisms.

C: OSPF LFA provides fast reroute after failure detection but doesn’t accelerate detection itself.

E: Flex links are used in Layer 2 switching, not for OSPF-based WAN failover.