Fibre Channel (FC) ports can be connected as point-to-point links, in a loop or to a switch. The ports in a point-to-point connection are called N_Ports; if they can work in a loop they are called NL_Ports. An FC switch, or a network of switches, is called a fabric. The ports of it are called F_Ports.
Both optical and electrical media are supported, working from 133 Megabits/sec up to 1062 Megabits/sec, while distances up to 10 km are possible.
Information can flow between two ports in both directions simultaneously. Exchange is the name of the mechanism for coordinating the exchange of information between two N_Ports. The port starting the Exchange is called the Originator, the port that answers is called the Responder. The data is sent in frames that are maximum 2148 bytes long. Frames have a header and a checksum. A set of related frames for one operation is called a Sequence. For flow control the Fibre Channel standard uses a look-ahead, sliding-window scheme that also provides a guaranteed delivery capability. FCS has the ability to carry multiple existing protocols including IP and SCSI.
 “Fibre Channel: Connection to the Future”, The Fibre Channel Association, 12407 MoPAC Expressway North 100-357, P.O. Box 9700, Austin, TX 78758-9700, 1994. Tel: 1-800-272-4618 or (512)-301-2402. Fax: (408)296-4457