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If there is a short or open on pairs 1,2 and 3,6 all communications
will be prevented. If there is a short or open on pairs 4,5 or 7,8 the
data rate may drop.
A faulty cable with missing or faulty pairs 4,5 or 7,8 may cause the
data rate on that cable to drop. If this faulty cable is between a PC
and hub or switch, all data going to and from that single PC will be
at a slow rate. If the faulty cable is between two hubs or switches
then communications will be quick at times and slow other times.
Communications between PCs connected to the same hub or switch
will be quick. Communications between a PC on one hub or switch
across a faulty cable to a PC on another hub or switch will be slow.
This type of problem can be very difficult to find without a TVR1000.
Real World Certifier: If your job requires testing the speed
parameters of a cable (is it Cat 5E? is it Cat 6?) and printing test
results, take a look at the Byte Brothers Real World Certifier at www.
bytebrothers.com. It has all of the features of the TVR1000 plus ad-
ditional troubleshooting capabilities that might be helpful in your job.
42
Appendix C. Ways to minimize LAN problems.
Use Category 5E cable (rated at 1000 MB/s).
●
Connect all four pairs when installing cables.
●
Use straight thru connections for installed cables.
●
Install all cables using standardized color code.
●
Use color coded patch cables with all four pairs wired.
●
Use TVR1000 to test each cable as it is installed.
●
Preferred Cables. The preferred wiring configuration for Ethernet
connections is based on the AT&T 258A standard (also called
EIA/TIA 568B). See Appendix A for the pinouts of the cable.
Two wrongs do not make a right!
Wire all sockets and cables according to the standards. This will
save countless hours of troubleshooting time.
Do not deviate from the standard cable pin outs. i.e. when testing
a cable be sure that both ends of the cable adhere to the standard
straight thru pin out and standardized wire color code.
When you find a missing wire on an installed cable. Open the near-
est wall jack and check that it is wired correctly according to color
code. If the nearest wall jack is correct, go to the other wall jack to
correct the problem. Be sure both ends are wired correctly.
If the near end wall jack is wired correctly, do not attempt to correct
pinout errors made on the other jack by swapping wires on the
correct wall jack. This mixes pairs, which makes LANs unreliable
may cause LAN ports to drop to low data rates causing bottlenecks
in the LAN operation. Wire both sides of cables correctly and
remember "two wrongs do not make a right."
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