Odd Cat5e issue

[mloiterman]

My whole house is wired with cat5e. I have two RJ45 jacks in each room/location terminated in keystones using 568a. All the cables go back to a patch panel and are also terminated with 568a.

I have tested all ~40 connections and they all test and work perfectly with one exception.

One keystone tests correctly (it shows that all the pins are connected), but the tester says that the cable is crossed over.

Initially I assumed there was a mistake at the keystone but upon examination, the cables appeared to be punched down correctly. I ripped it out and punched the keystone down again, this time using 568b. Again, testing showed that the cable was crossed over.

I ripped it out and punched it done again, this time 568a, as it was originally. The tester still shows that it all the pins are connected, but that the cable is crossed over.

This happens with two different ethernet testers.

I have used/functionally tested the cable extensively running gigabit transfers, PoE, and pings for 45 minutes to an hour and not a single packet is lost. So it appears the cable is functionally perfect.

The only thing I haven't down is to examine and re punch down at the patch panel since it's hard to get to at this point (my rack is kind of full). Any ideas on what would cause this to happen?

 

[ScottMac]

Try a different jumper.
Verify that the keystone is the same mfr and model as the others.
Verify the connection on the panel.

 

[mloiterman]

Different Jumpers were used each time I tested and the keystone is leviton like the others.

Could a defective keystone cause this?

 

[ScottMac]

Possible, not likely. Which pair(s) is showing defective?

 

[alkemyst]

My whole house is wired with cat5e. I have two RJ45 jacks in each room/location terminated in keystones using 568a. All the cables go back to a patch panel and are also terminated with 568a.

I have tested all ~40 connections and they all test and work perfectly with one exception.

One keystone tests correctly (it shows that all the pins are connected), but the tester says that the cable is crossed over.

Initially I assumed there was a mistake at the keystone but upon examination, the cables appeared to be punched down correctly. I ripped it out and punched the keystone down again, this time using 568b. Again, testing showed that the cable was crossed over.

I ripped it out and punched it done again, this time 568a, as it was originally. The tester still shows that it all the pins are connected, but that the cable is crossed over.

This happens with two different ethernet testers.

I have used/functionally tested the cable extensively running gigabit transfers, PoE, and pings for 45 minutes to an hour and not a single packet is lost. So it appears the cable is functionally perfect.

The only thing I haven't down is to examine and re punch down at the patch panel since it's hard to get to at this point (my rack is kind of full). Any ideas on what would cause this to happen?

Your cable is compromised somewhere along the run...more than likely a nail or screw was put through it.

 

[mloiterman]

Your cable is compromised somewhere along the run...more than likely a nail or screw was put through it.

How can that be? The cable works perfectly and multiple testers, jumpers, etc. all show all the pins connected - just crossed over.

I would think a nail would wipe out some of the pins ability to connect and show issues with connectivity, packet loss, ability to hold PoE...no?

 

[alkemyst]

I can't see the cable, but if you have it pinned correctly at both ends and getting a crossover along the way, it's got to be a compromise in the cable or your equipment.

Your gear also more than likely does auto-mdx correcting the crossover internally.

 

[Chess]

I know on my keystones it shows a and b did you do b by accident and a on one end ? i am just thinking i am not sure....

If it is crossed its crossed simple as that