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Eterhnet reversed pairs....

Eterhnet reversed pairs....

Eterhnet reversed pairs....

I ran across a patch bay was wire with the pairs reveresed.
ie. orange orange/white were reversed.  All four pairs werer reversed.  This has worked this way for many years!
The reason this happened was that the patch bay at one end was Hubble and the other end was Aims. And the punch down connectors are different.
I discovered this using a HP Wirescope to certify the runs.

The question is:   What effect does reversed pairs have?  What kind of problems does it cause?

RE: Eterhnet reversed pairs....

Probably wouldn't have any effect if they're reversed, provided the cables still use the same pairs.  Each pair of wires forms a balanced line by virtue of the fact that they are uniformly twisted together and are of equal length.  So each wire in the pair should be identical in every way, (except for the insulation colour!), i.e. diameter of inductor, resistance of inductor, thickness of plastic insulation etc. - it wouldn't be balanced if they weren't.

Hope that helps...


RE: Eterhnet reversed pairs....

Pair reversals on UTP cabling may cause problems when trying to use some devices. I assume that if you found the problem with a Wirescope that the pairs are reversed at only one end of the cable. If the pairs are reversed on both ends of a particular cable - It is improperly installed but will cause no problems. Some devices such as hubs, switches, and routers will detect the reversal and correct it internally. But others may not. A good cabling installation will contain No Pair Reversals. If I paid for a certified cabling installation - I would contact the contractor and have them correct any reversals and provide test documentation.

Keith M. Wolcott, RCDD

RE: Eterhnet reversed pairs....

The problem you found sounds like a mismatch of terminating hardware. You may have a 568A patch panel at one end and a 568B patch panel at the other end. You should be able to determine the pinout of the panels by examining them closely for manufacturer's markings.

RE: Eterhnet reversed pairs....

kcottrcdd has the correct answer.

RE: Eterhnet reversed pairs....

without knowing more about what used the wire one consideration could be that it is a 'cross-over' cable for use between two data 'switches'.  router to switch = straight thru cable.  like to like = cross-over,  
re:router-router, switch-switch.  tcom 101, the old dce and dte considerations.

RE: Eterhnet reversed pairs....

If The UTP Cable Reversed, Transmit & Receive must change and that cable will not work properly. But If two Machines are directly connected without any hub or switch it will work properly. But There is no need of connecting cables in twisted method while using a hub or switch. In this case we have to crimb the UTP cable in the same manner which you crimbed the first end.

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