Information Technology Reference
In-Depth Information
1
CHAPTER
Troubleshooting Overview
Dependency on network resources has grown tremendously over the past ten years. In today's world, a
company's success is highly dependent on its network availability. As a result, companies are
increasingly less tolerant of network failures. Therefore, network troubleshooting has become a crucial
element to many organizations.
Not only has the dependency for network grown, but the industry also is moving toward increasingly
complex environments, involving multiple media types, multiple protocols, and often interconnection to
unknown networks. These unknown networks may be defined as a transit network belonging to a Internet
service provider (ISP), or a telco that interconnects private networks. The convergence of voice and
video into data networks has also added to the complexity and the importance of network reliability.
More complex network environments mean that the potential for connectivity and performance problems
in internetworks is high, and the source of problems is often elusive.
Symptoms, Problems, and Solutions
Failures in internetworks are characterized by certain symptoms. These symptoms might be general
(such as clients being incapable of accessing specific servers) or more specific (routes not existing in a
routing table). Each symptom can be traced to one or more problems or causes by using specific
troubleshooting tools and techniques. After being identified, each problem can be remedied by
implementing a solution consisting of a series of actions.
This topic describes how to define symptoms, identify problems, and implement solutions in generic
environments. You should always apply the specific context in which you are troubleshooting to
determine how to detect symptoms and diagnose problems for your specific environment.
General Problem-Solving Model
When you're troubleshooting a network environment, a systematic approach works best. An
unsystematic approach to troubleshooting can result in wasting valuable time and resources, and can
sometimes make symptoms even worse. Define the specific symptoms, identify all potential problems
that could be causing the symptoms, and then systematically eliminate each potential problem (from
most likely to least likely) until the symptoms disappear.
Figure 1-1 illustrates the process flow for the general problem-solving model. This process flow is not a
rigid outline for troubleshooting an internetwork; it is a foundation from which you can build a
problem-solving process to suit your particular environment.
