AIR-LAP1231G-A-K9 no longer connects to controller after switch runs test cable-diagnostics tdr

[CrispyMouse]

Attempting to troubleshoot connectivity issues with AIR-LAP1231G-A-K9.  Suspected a cable issue so ran the "test cable-diagnostic tdr" from the switch.  The test failed to complete.  So the test was run on a working AIR-LAP1231G-A-K9.  That AIR-LAP1231G-A-K9 is no longer connecting to the controller but is connected to a Cisco 3560 switch with gigabit ports.

The AIR-LAP1231G-A-K9 has an IP address and is pingable but will no longer connect to the controller after a TDR diagnostic being run.  The port has been shutdown and then reopened "no shut" but it still won't connect to the controller.

Any ideas why the TDR diagnostic would do this and how to fix remotely?  (In testing repeated this four for four).

[Leo Laohoo]

What you are seeing is a normal behaviour.  Let me explain.  

When you run a TDR, all FOUR PAIRS are tested.  When TDR is tested on the PoE pair, the PoE has to be disabled first before a TDR is done.  This is why your AP went dead during TDR. 

Now, as to the result of "not completed" there are only two scenarios you see this result.  They are: 

1.   Switch hardware:  3560-series family of switches, 4000/4500 and 6000/6500 line cards take 61 seconds to run a TDR.  So run the "sh cable tdr interface <BLAH>" after 61 seconds and sometimes you'll see the result.  

2.  Cable:  Your cable is so bad the electrical signal to run the TDR gets "garbled up".  

If you are seeing issues with option #2, I would recommend you have to do this in steps.  Say you have this scenario:   switch - cable - patch port -- horizontal cabling -- patch port - AP. 

From left to right now ... Disconnect the cable (closest to the switch) from the patch port (not from the switch).  Run the TDR.  If all goes well, proceed.  If not, replace the cable.  Run the TDR again until result is satisfactory.  

Next, disconnect the patch cable from the patch panel nearest the switch.  Run the TDR.  

Next, reconnect the patch cable back to the patch panel and disconnect the cable from the TDR.  Run the TDR.  

Be aware, that when you are running 4000/4500 and/or 6000/6500 TDR, the results can be misleading.  Post them if you have doubts.