Upon completing this chapter, you should be able to do the following:
Describe how to diagnose and isolate problems with LANs.
Describe how to troubleshoot network malfunctions.
Explain how to test and evaluate the connection of networking system nodes.
Explain how to troubleshoot communications line problems.
With any network system, you should have a set of
error procedures for personnel to follow to handle errors
or malfunctions on the system. These error procedures
are the steps to be taken when the system is not
operating properly. They are different from the error-
detection and diagnostic procedures used to isolate and
correct transmission problems.
A complete set of diagnostic procedures is
necessary for the system. The system procedures are
used to isolate the problem to the system or subsystem
level. Since the facilities of a network may not be in the
local area, it is necessary to have a set of test software
and equipment with replacement components available
for diagnosing and correcting problems.
As a communications specialist, more than likely
you will be expected to know how to troubleshoot
problems on LANs. As a troubleshooter, you must be
able to identify a wide range of network problems
relating to hardware (the data terminal equipment, the
communications link, repeaters, gateways, and so on),
software (network operating system, applications, and
soon), and peopleware (the end user). It will be your job
to identify, isolate, and resolve both the simple and
Normally, a problem can be solved without too
much difficulty with the help of diagnostic tools. The
best diagnostic tool available is accurate
documentation. This documentation should include:
Workstation and server configurations
All network related software and equipment
Location and paths of all wiring
Updated records of all equipment and
With documentation in hand, along with the help of
diagnostic software (a network management package or
a LAN analyzer), and specialized diagnostic
equipment, such as a datascope, a time domain
reflectometer (TDR), or a breakout box, the job
Classifying the problems and taking the necessary
actions to resolve them are an important part of your job
as a troubleshooter. However, it is equally important to
remember to log all problems according to your
activitys procedures. This will identify recurring
problems, provide information for long term solutions,
and enhance your commands training program.
When isolating a problem, consider the three major
areas we discussed earlier-the user, the software, and
the hardware, usually in that order. The majority of all
network-related problems are caused by the users
actionsoperator errors. Users either do not
understand how to operate their PC in a networking
environment or they are unfamiliar with the application
software package they are using. Most of the time you
will find yourself responding to user problems and
complaints. A user will call, saying such things as the