Understanding the network.pdf - Back to Home

Network Errors
Knowing the amount and type of errors generated on the network segment is
important for determining the segment's performance, and for properly
troubleshooting performance problems and network outages, when they occur.
During the network baselining process, a certain percentage of network errors are
collected. Although network errors represent some type of abnormal transmission
event, not all errors are an indication of a hard failure. In most cases, errors are
indications of operational disturbances in the normal data transmission flow (which
might even be necessary for proper operation). In some cases, network errors can
be addressed by the transmission protocol without an administrator's intervention.
Errors, in other cases, are an actual by-product of the data transmission process
(Ethernet Collisions, for example) that are needed for the transmission process to
function normally.
Under normal operation, network error rates should be a low percentage of the
overall bandwidth utilization (1 to 3 percent). A high rate of errors, (being a
consistent error rate of using 5 percent or more to the segments bandwidth) is an
indication of problem that requires further investigation to identify the error source.
Typically, a high-error percentage rate is an indication of failing hardware or
software driver, a mis-configuration in circuit provisioning (WAN links), or a
violation of transmission cable length specifications. Each of these impacts the
performance of the device with which it is associated. However, excessive error
rates also degrade network performance on the whole, by consuming bandwidth
that would otherwise be used for sending data. Additionally, depending on the type
of network error, the segment might evoke "recovery processes" or "transmission
back-off algorithms" in an attempt to stabilize the segment. Both of these events
effectively halt data transmission during the initiation process, further degrading
performance.
With the exception of WAN transmission equipment, most error conditions are only
visible through the use of a network probe and a network management/analysis tool.
Intermittent or unexplained network performance drops overall degradation in
network performance (for example, excessive local network transaction times,
unexpected service disconnects, and so on) and are operational indications of the
existence of an error condition and, unless you have deployed error recording and
event alarming, might be your only indication of a problem. Listen to your users and
take performance complaints seriously. Although the majority of complaints might
be nothing, the ones that are serious, if identified early, can be corrected before
they gravely impact network service.
Now, lets take a look at some of the different types of transmission and
delivery-related errors.