http://www.rfc-editor.org/rfc/rfc5880.txt
RFC 5880: Bidirectional Forwarding Detection (BFD), D. Katz, D. Ward2010-06-01T23:00:00-00:00This document describes a protocol intended to detect faults in the bidirectional path between two forwarding engines, including interfaces, data link(s), and to the extent possible the forwarding engines themselves, with potentially very low latency. It operates independently of media, data protocols, and routing protocols. [STANDARDS-TRACK]