Introduction

This chapter provides an overview of the general structure, concepts, organization, and mechanisms of the Fibre Channel protocol. This will provide a background for the detailed discussions of the various parts of the architecture in the following chapters and will give pointers on where to find information about specific parts of the protocol.

A Fibre Channel network is logically made up of one or more bidirectional point-to-point serial data channels, structured for high-performance capability. The basic data rate over the links is just over 1 Gbps, providing >100 MBps data transmission bandwidth, with half-, quarter-, eighth-, double-, and quadruple-speed links defined. Although the Fibre Channel protocol is configured to match the transmission and technological characteristics of single- and multi-mode optical fibers, the physical medium used for transmission can also be copper twisted pair or coaxial cable.

Physically, a Fibre Channel network can be set up as (1) a single point-to-point link between two communication Ports, called N_Ports, (2) a network of multiple N_Ports, each linked through an F_Port into a switching network, called a Fabric, or (3) a ring topology termed an Arbitrated Loop, allowing multiple N_Port interconnection without switch elements. Each N_Port resides on a hardware entity such as a computer or disk drive, termed a Node. Nodes incorporating multiple N_Ports can be interconnected in more complex topologies, such as rings of point-to-point links or dual independent redundant Fabrics.

Logically, Fibre Channel is structured as a set of hierarchical functions, as illustrated in Figure 2.1. Interfaces between the...