Fibre Channel Unraveled

Steve Nelson

Fibre Channel (FC) is not really an emerging technology, since it is based on mainframe fiber directors for ESCON that were developed more than ten years ago. It's the speed, implementation, and "openness" that makes FC new. This article will provide a brief overview of the technology, which will include a view into what FC is all about, the FC protocol that makes it work, the devices from which you build FC-based networks, and some sample topology philosophies that will provide starting points from which to design flexible layouts.

Most vendors tout FC's speed (100 MB/sec or 1 Gb/sec), and distance capability (anywhere from 500 m to 10 km, depending on implementation). Based on this, the inclination is to simply substitute fiber for SCSI cables and build point solutions to ever increasing amounts of storage. However, FC also represents a new way to look at your data storage in the "open" environment. FC allows a system/storage administrator to build networks of storage nodes, accessible by any other node attached to the network. These networks of storage have various names depending on vendor; however, the most common are the Storage Area Network (SAN) and the Enterprise Storage Network (ESN). The difference between the two lies in the scope of the implementation: the SAN covers a point, or small-scale solution to an immediate problem, while the ESN is a broader solution covering most, if not all, CPUs within a given environment.

Looking at the name of the technology, it would be easy to conclude that this only runs on fiber optic cabling. In fact, the FC protocol runs over single mode and multi-mode fiber cabling, as well as various copper implementations, including both Twinax and Twisted Pair.