Bidirectional Forwarding Detection (BFD) is a super fast
protocol that is able to detect link failures within milliseconds
or even microseconds. BFD runs independent from any other (routing)
protocols. Once it’s up and running, you can configure protocols
like OSPF, EIGRP, BGP, HSRP, MPLS LDP etc. to use BFD for link failure
detection instead of their own mechanisms. When the link fails,
BFD will inform the protocol