Fibre Channel General Introduction

The Fibre Channel Standard (FCS) [1] defines a high-speed data transfer interface that can be used to connect together workstations, mainframes, supercomputers, storage devices and displays. The standard addresses the need for very fast transfers of large volumes of information and could relieve system manufacturers from the burden of supporting the variety of channels and networks currently in place, as it provides one standard for networking, storage and data transfer.

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.

References

[1] X3T9.3/Project 755D/Rev 4.2, “Fibre Channel Physical and Signalling Interface (FC-PH)”, Working draft, ANSI, October 8, 1993.

[2] “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

Erik.van_der_Bij@cern.ch - 8 August 1994