Problems happen! Even when the network
is monitored, the equipment is reliable, and the users are careful,
things may go wrong. The test of a good network administrator is the
ability to analyze, troubleshoot, and correct problems under pressure
of a network failure that causes company downtime. Good network
administration techniques were described in Semester 3. The
suggestions below review those techniques as well as offer other tools
for troubleshooting a network. Here is a review of previous and some
additional techniques for troubleshooting a network. These techniques
as stated before can be the best tools in curing network problems.
The first and most important thing is to
use your engineering journal and take notes. Note taking can define a
clear path to diagnosing a problem. It can tell you what you have
already tried and what effect it had on the problem. This can be
extremely valuable to the troubleshooter so those previous attempts at
resolving the problem won't be needlessly repeated as time goes on.
Taking notes is also very valuable if the problem is handed off to
another technician to prevent them from having to redo all of the work
that was already done. A copy of these notes should be included with
the resolution of the problem when the trouble ticket on this job is
completed. This can provide a reference for any similar problems that
might happen related to this particular problem. 
Another essential element of preemptive
troubleshooting is labeling. Label everything, including both
ends of a horizontal cable run. This label should
include not only the number of the cable but also where the other end
is located and the usage of the cable, for example, voice, data or
video. This type of label can be even more valuable than a wiring cut
sheet when it comes to troubleshooting, because it is located right
where the unit is and not stuck in a drawer somewhere. Along with the
wire labels, labeling each port on a hub, switch or router as to
location, purpose, and point of connection will greatly improve the
ease with which problems can be solved. Finally, all other components
attached to the network should also be labeled as to their location
and purpose. With this type of labeling, all components can be located
and their purpose on the network easily defined. Proper labeling, used with the
network documentation created when the network was built and updated,
will give a complete picture of the network and its relationships. One
other important reminder from the previous semester is that the
documentation is only useful if it is current. All changes made to the
network must be documented both on the devices or wire that is changed
and the paper documentation used to define the complete network.
The first step in network
troubleshooting is the definition of the problem. This
definition can be a consolidation of many different sources. One of
the sources could be a trouble ticket or help desk report, which
initially identifies a problem. Another might be a phone conversation
with the user having the problem to gather more information about the
problem. Network monitoring tools may provide a more complete idea
about the specific problem to be resolved. Other users and your own
observations will provide information. Evaluating all of this
information may give the troubleshooter a much clearer starting place
to resolve the problem, rather than by working from any one of the
sources alone.
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