High Quality Content by WIKIPEDIA articles! Fabric Shortest Path First (FSPF) is a routing protocol used in Fibre Channel networks. It calculates the best path between switches, establishes routes across the fabric and calculates alternate routes in event of a failure or topology change. FSPF can guarantee in-sequence delivery of frames, even if the routing topology has changed during a failure, by enforcing a `hold down` time before a new path is activated.