In the contest of Storage Area Networking, Fibre Channel is used to connect servers to storage arrays. The fibre channel protocol itself is optimised for carrying block data and can carry a number of protocols at the applcation level. For SAN this is SCSI but other protocols, such as IP are available. It can be used in 3 topologies, point to point, arbitrated loop or switched. The following url gives an introduction to Cisco's use of Fibre Channel for SAN.
