Fibre Channel Basics Part 1

Fibre Channel is a high speed network technology. It is mainly deployed in storage (SAN) environments but was originally developed as a replacement for Fast Ethernet and Fibre Distributed Data (FDDI) networks. In the next series of posts I will explain the concepts and terminology that make up the Fibre Channel Protocol.


Fibre Channel Protocol Layers and Protocol  Structure

The Fibre Channel Protocol contains 5 layers FC-0 to FC-4. FC-0 to FC-3 are mainly responsible for the physical interfaces, encoding and addressing. FC-4 defines how the upper layer protocols such as; SCSI or IP, interact with the Fibre Channel network.

Fibre Channel Topologies 

There are three topology types used in fibre channel networks.

• Point to Point  - in this topology a full duplex connection is used between devices 
• Arbitrated Loop - in an arbitrated loop topology multiple devices are connected in a unidirectional ring and only two devices at a time can transfer data with each other.
• Fabric - This is the most common topology. With this structure all devices contented to the fabric can transfer data at the same time using the full bandwidth of the link. For this topology a Fibre Channel switch is required.

Ports

In the Fibre Channel architecture each port contains a input and a output channel.

Links

The connection between each port is, you guessed it, called a link. How the connection is made between devices and the flow of data can differ between topologies. In Point to Point and Fabric topologies links are always bidirectional, the input channel has a connection with the output channel with the other device.

This is an example of a point to point toplogy

This is an example of a aggregated loop topology

 This is an example of a fabric topology

Please excuse the diagrams it was late and all I had was MS paint to work with. Each topology also has certain port types defined to allow the devices to operate with each other. In the next series I will discuss the port types and the individual layers that make up the fiber channel protocol.