Symptoms, Problems, and Solutions
Failures in networks are
characterized by certain symptoms. These symptoms might be general, such as the
inability to gain Internet access. Symptoms may also be more specific, such as
the inability to access specific servers. Using specific troubleshooting tools
and techniques can identify the problems or causes of each symptom. Once
identified, each problem can be remedied by implementing a solution consisting
of a series of actions.
General Problem-Solving Model
When troubleshooting a network
environment, a systematic approach works best:
- Define the problem and gather the symptoms.
- Identify all potential causes that could be creating the symptoms observed.
- Eliminate each potential problem, from most likely to least likely, until
the symptoms disappear.
Figure
illustrates the
process flow for the general problem-solving model. This process flow is not a
rigid outline for troubleshooting a network. It is a foundation upon which a
problem-solving process can be built to suit a particular environment. The
flowchart in this section provides the specific steps needed to complete the
process.
When a network is down, a systematic approach is required to
restore it. In most troubleshooting scenarios, it is best to move from the
general to the specific and eliminate unrelated variables to focus on the
subset of variables that contains the solution. This is a fundamental principle
of science and is not only applicable to network engineering. Breaking complex
problems down into smaller steps and determining the relationships between them
can help simplify the formation of a total solution after solving the smaller
problems.
In some situations, the hardest part of troubleshooting is
documentation after the problem is solved. A sample network diagram serves as a
focal point for the compiled documentation. Careful documentation is a
necessary process that will simplify life for the engineer and others in the
organization. Documentation should be completed once during the WLAN site
survey and again after the completed installation and testing phase. The lack
of documentation can be a contributing factor in many problems. This is
especially true when the staff does not have an accurate view of the current
network status or past network performance. Documentation should provide clear
and easily accessible information to those who need it. This information should
also be easy to update. It is important to remember that documentation
simplifies network management and greatly reduces the time required for problem
resolution.