Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Community Member

3905 IP Phone and cable test failure

Hello! Today we noticed that if trying to run tdr cable test on catalyst 2960s on port with plugged 3905 IP phone we always getting results like that:

Interface Speed Local pair Pair length        Remote pair Pair status
--------- ----- ---------- ------------------ ----------- --------------------
Gi1/0/19  100M  Pair A     67   +/- 0  meters N/A         Normal              
                Pair B     68   +/- 0  meters N/A         Normal              
                Pair C     69   +/- 1  meters N/A         Short               
                Pair D     68   +/- 1  meters N/A         Short    

 

Is it ok or not? Another phone models have all normal pair in same port.

7 REPLIES
Hall of Fame Super Gold

Interface Speed Local pair

Interface Speed Local pair Pair length        Remote pair Pair status
--------- ----- ---------- ------------------ ----------- --------------------
Gi1/0/19  100M  Pair A     67   +/- 0  meters N/A         Normal              
                Pair B     68   +/- 0  meters N/A         Normal              
                Pair C     69   +/- 1  meters N/A         Short               
                Pair D     68   +/- 1  meters N/A         Short    

Read this:  How to use Time-Domain Reflectometer (TDR)

 

Pair C controls PoE.  Because there's a "short" at around 68-69 (cable) metres from the switch, it means your device won't power up. 

 

Pair D controls GigabitEthernet.  Because there's a "short" at around 68-69 (cable) metres from the switch, it means your device won't be able to operate and/or negotiate at GigabitEthernet. 

 

This is indicative of a cable problem.  The cable is most likely to be the one that's cabled up to the phone.  

Community Member

Thanks for your reply! We

Thanks for your reply! We thought about cable problem and tried to change cable but nothing helps. And moreover - all our 3905 phones on any ports and any cable give this error... 

Hall of Fame Super Gold

Take the phone and plug

Take the phone and plug directly into the switchport.  If the phone works, then your issue could be the following: 

 

1.  The remote end patch port; and

2.  The remote end patch cable

Community Member

> Take the phone and plug

Take the phone and plug directly into the switchport.  If the phone works, then your issue could be the following: 

Did it already, error is the same but phone is working regardless it plugged directly or not. So is it normal beaviour for thie phone model or not?

Hall of Fame Super Gold

Hmmmm ... What is the IOS

Hmmmm ... What is the IOS version of your switch?

Community Member

Switch Ports Model          

Switch Ports Model              SW Version            SW Image                 
------ ----- -----              ----------            ----------               
*    1 28    WS-C2960S-24PS-L   12.2(55)SE7           C2960S-UNIVERSALK9-M     

 

Hall of Fame Super Gold

For 2960S, upgrade your IOS

For 2960S, upgrade your IOS to 12.2(55)SE9 or 15.0(2)SE4.  

 

I remembered seeing an IOS in the early 15.0(2)SE where the TDR result gets "stuck" and you'll need to reboot the entire chassis just to reset the result.

56
Views
0
Helpful
7
Replies
CreatePlease to create content