Cisco 7941 displays Ethernet Disconnected but works on other switch

[Pablo Pinzon]

Hello

Today I found a 7941 with the common "ethernet disconnected" problem that is normally attributed to bad hardware. However, upon connecting it to a different switch it loaded up just fine. 

I found this odd since I know for a fact that the wall port to which it was originally connected works fine and is currently working with a different phone.

Are there any other known reasons to get ethernet disconnected on what seems to be a perfectly working phone?

ANSWER: Just noticed that it connected while i was moving it. The port on the phone seems to be a bit loose and applying pressure in the right directions makes the pins connect. Probably the direction from the cable when connecting to the other switch would apply the pressure necessary for the pins to connect

Thanks for the replies

[Stephen Welsh]

This is typically a bad patch lead, try with another/new one, basically the phone is getting power but has not been able to communicate properly over the cable.

Kind Regards

Stephen Welsh

CTO

UnifiedFX

[Pablo Pinzon]

The patch is working OK and as I mentioned, other phones have no problem loading up in that port, discarding the problem from being a bad physical connection 

[Aseem Anand · Accepted solution]

Hi,

It could be an issue with the cabling or the connector. Did you use the same cable when connecting to the different switch? If not then can you try to connect to the different switch using the same cable.  Are you using a patch panel as well? Also, can you let us know the model of the two switches you are using.

Aseem

[Pablo Pinzon]

I did use the same cable and since there's another phone working there without problem I discarded the cabling. 

The switches are:

c3750g  (where phone doesn't work)

c2960  (phone works fine)

To fully discard the cabling I ran a tdr test:

TDR on 3750 with working phone: 

Interface Speed Local pair Pair length Remote pair Pair status
--------- ----- ---------- ------------------ ----------- --------------------
Gi1/0/27 1000M Pair A 37 +/- 4 meters Pair A Normal 
               Pair B 39 +/- 4 meters Pair B Normal 
               Pair C 39 +/- 4 meters Pair C Normal 
               Pair D 38 +/- 4 meters Pair D Normal 

TDR test on 3750 with "non-working" phone 

Interface Speed Local pair Pair length Remote pair Pair status
--------- ----- ---------- ------------------ ----------- --------------------
Gi1/0/27 auto Pair A 38 +/- 4 meters N/A Open 
              Pair B 40 +/- 4 meters N/A Normal 
              Pair C 40 +/- 4 meters N/A Normal 
              Pair D 39 +/- 4 meters N/A Open 

TDR test on 2960 with "non-working" phone

Interface Speed Local pair Pair length Remote pair Pair status
--------- ----- ---------- ------------------ ----------- --------------------
Fa0/5     100M Pair A 128 +/- 15 meters Pair B Normal 
               Pair B 128 +/- 15 meters Pair A Normal 
               Pair C N/A               Pair D Not Supported 
               Pair D N/A               Pair C Not Supported