Fibre Channel Testing Strategies

Fibre Channel Introduction

Fibre Channel (FC) is a high-speed network technology that enterprises rely on to transport data to remote sites and store it for protection against potentially damaging natural and human events. It is designed to meet the many requirements related to the ever increasing demand for high performance information transfer. The goals of Fibre Channel are to develop practical, inexpensive, yet expendable means of quickly transferring data between workstations, mainframes, supercomputers, storage devices, displays, desktop computers and other peripherials. Although being called Fibre Channel, its architecture does not represent neither a channel nor a real network topology. It allows for an active intelligent interconnection scheme, called a Fabric, to connect devices. The purpose of the Fibre Channel port is to manage a simple point-to-point connection between itself and the Fabric.

Why Test Fibre Channel?

Fibre Channel aims to carry different types of traffic for applications that require first-rate capabilities of storage. The principal trait of Fibre Channel is the fusion of the network technologies, which allows the communications to have some attributes including high bandwidth, low latency, high data integrity, high connectivity, and large distances, etc. Because of its stringent performance requirements, Fibre Channel requires extensive testing during deployment in order to assure the desired service level.

Fibre Channel Testing Strategies

There are three basic types of test instrument apparatus useful in testing Fibre Channel system. They are two-channel pass-through protocol analyzers, data or pattern generators, or emulators.

The two-channel pass-through protocol analyzer is useful in debugging the correctness of the Fibre Channel transport protocol on the physical links as well as assisting in debugging the user applications running on the link. Besides, it is able to be used to stream data to secondary storage for post run analysis. A pattern generator is able to stress the link’s ability to handle data, send legal and illegal user application data, and perform illegal Fibre Channel operations. Building onto the data generator the ability to respond to link inputs in real-time makes a useful tool for hosting applications under test or for emulating systems to other Devices-Under-Test (DUT). In short, this “emulator” can provide a complete, flexible lab environment in which to stimulate and test a DUT.

In addition to the above testing strategies, there is still another issue to be considered, that is, Fibre Channel should be tested with or without the patch cords? To answer this question, the following factors should be clear first.

As a matter of fact, the main deciding factor for whether to test the Fibre Channel with the patch cords included or to just test the permanent links depends on the specification offered by the end user or their consultant. If needed, the Fibre Channel should be tested with the patch cords. Afterwards, if the question is still unclear after checking the specification, you can consider the fact that patch cords are factory terminated and offer a lower risk of defect and errors. Installing permanent link has much more impact on the performance and insertion loss of the Fibre Channel. Sometimes, testing the Fibre Channel with the patch cords is not logistically feasible as the patch cords are not in place during initial testing before active equipment is installed and up and running. The last factor is that typical insertion loss values or maximum insertion loss values are used to design the Fibre Channel or not. If using typical insertion loss, it is important to know how the patch cords impact the Fibre Channel. Even a negligible loss on the patch cords can have an impact on the design and the Fibre Channel performance. If using maximum insertion loss values, patch cords will not have an impact.

After reading the above description, the answer to Fibre Channel testing with or without patch cords is “it depends”. For the other Fibre Channel testing strategies, each has its own features. when you need to test the Fibre Channel, make clear each strategy and then make the correct decision to maximize your network performance.

Originally published at www.fiber-optic-components.com/