Fluke Network Tester - Manual (Page 57)

Common Problems
Problems NetTool Detects
6
6-5
Network Problems
This section lists all of the network problems. Keep in mind
that this is not an exhaustive list of troubleshooting steps.
If you know what you need, the network administrator for
the network you are troubleshooting can provide you with
a lot of information to correct these problems.
Health Problems
•
Problem: Short Frames received (also jabber/FCS).
Explanation: A short frame is a frame that is smaller
than the minimum legal size (less than 64 bytes after
the preamble) with a good frame check sequence.
Jabber is defined as frames longer than the maximum
legal size (greater than 1518 bytes). Frame Check
Sequence (FCS) Bad means that the header
information is probably correct, but the checksum
calculated by the receiving station does not match the
checksum appended to the end of the frame.
Remedy: Check the NIC card or NIC driver file. This
problem can also be caused by cabling or grounding
problems.
•
Problem: Excessive utilization seen (also collisions).
Explanation: Excessive utilization/collisions is
defined as a collision rate of greater than 5 percent or
a utilization rate of greater than 70 percent.
Remedy: If this problem exists everywhere on the
network, it is most likely caused by excessive traffic. If
it is isolated to a single PC, you can suspect cabling.
For collisions, suspect excessive traffic. Reduce traffic
on the network. Check cabling. Change the NIC card
or switch/hub port.
For utilization, reduce the number of stations in the
collision domain. Install a switch. Use a tool like the
OptiView™ Network Analyzer, Etherscope™ Network
Assistant, or OptiView™ Console to determine the top
contributors to further segment this network.