Bidirectional Forwarding Detection (BFD)
BFD is a lightweight protocol that detects failures in the path between two routers within milliseconds.
What is Bidirectional Forwarding Detection (BFD)?
Routing protocols on their own can take seconds to notice a failed link. BFD exchanges frequent small hello packets and alerts protocols such as BGP or OSPF immediately when they stop, speeding up rerouting.