Protocols and standards
RFC 5880, Bidirectional Forwarding Detection (BFD)
RFC 5881, Bidirectional Forwarding Detection (BFD) for IPv4 and IPv6 (Single Hop)
RFC 5882, Generic Application of Bidirectional Forwarding Detection (BFD)
RFC 5883, Bidirectional Forwarding Detection (BFD) for Multihop Paths
RFC 5884, Bidirectional Forwarding Detection (BFD) for MPLS Label Switched Paths (LSPs)
RFC 5885, Bidirectional Forwarding Detection (BFD) for the Pseudowire Virtual Circuit Connectivity Verification (VCCV)