Content

| Overview

Troubleshooting networks is more important than ever. As time goes on, services continue to be added to networks. With each added service comes more variables. This adds to the complexity of the network troubleshooting as well as the network itself. Organizations increasingly depend on network administrators and network engineers having strong troubleshooting skills.

Troubleshooting begins by looking at a methodology that breaks down the process of troubleshooting into manageable pieces. This permits a systematic approach, minimizes confusion, and cuts down on time otherwise wasted with trial and error troubleshooting.

Network engineers, administrators, and support personnel realize that troubleshooting is a process that takes the greatest percentage their time. One of the primary goals in this module is to present efficient troubleshooting techniques, in order to shorten overall troubleshooting time when working in a production environment.

Two extreme approaches to troubleshooting almost always result in disappointment, delay, or failure. On one extreme is the theorist, or rocket scientist, approach. On the other is the practical, or caveman, approach. Since both of these approaches are extremes, the better approach is somewhere in the middle using elements of both.

The rocket scientist analyzes and re-analyzes the situation until the exact cause at the root of the problem has been identified and corrected with surgical precision. This sometimes requires taking a high-end protocol analyzer and collecting a huge sample, possibly megabytes, of the network traffic, while the problem is present. The sample is then inspected in minute detail. While this process is fairly reliable, few companies can afford to have their networks down for the hours, or days, it can take for this exhaustive analysis.

The caveman’s first instinct is to start swapping cards, cables, hardware and software until miraculously the network begins operating again. This does not mean that the network is working properly, just that it is operating. Unfortunately, the troubleshooting section in some manuals actually recommends caveman style procedures as a way to avoid providing more technical information. While this approach may achieve a change in symptoms faster, this approach is not very reliable and the root cause of the problem may still be present. In fact, the parts used for swapping may include marginal or failed parts swapped out during prior troubleshooting episodes.

Analyze the network as a whole rather than in a piecemeal fashion. One technician following a logical sequence will almost always be more successful than a gang of technicians, each with their own theories and methods for troubleshooting.