IP Phone will not register - Turns out to be bug: CSCtn11683

[tdennehy]

I have a really weird issue with a 3750 stack.  A gig port, 1/0/25 has an IP phone in it.  Works fine.

Port 1/0/48 has same exact config.  When I plug a phone into it, it will power up, but it will not register.

When I move the phone to port 25 (after disconnecting the known good phone) the phone will register.  When I take the known good phone and put it in port 48, it will not register.

The phone boots up just fine in port 48.  It is almost as if the port has an invisible ACL on it.  However, both ports have the same exact port config.  I even stripped the config out and set it as an access port in the voice vlan... and plugged in a laptop and did not get an IP address.  After shutting down the port and changing the vlan to the user vlan, it still did not receive an IP address.

I'm starting to think the port is somehow damaged.

Has anyone ever had an issue like this?  I have a few other ports in the same stack that do the same thing.  I think I have ruled out power budget because the phone boots up.  If there were a problem with power - it wouldn't come up at all.

Thanks in advance!

!

interface GigabitEthernet1/0/48

 switchport access vlan 32

 switchport mode access

 switchport voice vlan 128

 ip arp inspection limit none

 srr-queue bandwidth share 1 30 30 30

 priority-queue out

 mls qos vlan-based

 storm-control broadcast level bps 512k 256k

 storm-control multicast level bps 1.544m 768k

 storm-control action shutdown

 spanning-tree portfast

 spanning-tree bpduguard enable

end

!

interface GigabitEthernet1/0/25

 switchport access vlan 32

 switchport mode access

 switchport voice vlan 128

 ip arp inspection limit none

 srr-queue bandwidth share 1 30 30 30

 priority-queue out

 mls qos vlan-based

 storm-control broadcast level bps 512k 256k

 storm-control multicast level bps 1.544m 768k

 storm-control action shutdown

 spanning-tree portfast

 spanning-tree bpduguard enable

end

Gi1/0/25                     connected    32         a-full  a-100 10/100/1000Ba

seTX

Gi1/0/25  auto   on         6.3     IP Phone 7912       n/a   30.0

Turned out to be a bug:

https://supportforums.cisco.com/comment/9632936#comment-9632936

[Leo Laohoo]

I've seen cases like this.  Unfortunately, GOLD won't show anything.  

Put the phone back into Gi1/0/48 and post the output to the command "sh power inline Gi1/0/48".  

Also do the following:  

1. Command:  test cable tdr interface Gi1/0/48; 
2. Wait for 5 to 7 seconds; 
3. Command:  sh cable tdr interface Gi1/0/48; and 
4. Post the output to #3.

[tdennehy]

aj-rcp-sw-b20002-r201-1#
aj-rcp-sw-b20002-r201-1#sho power inline gi1/0/48
Interface Admin  Oper       Power   Device              Class Max
                            (Watts)
--------- ------ ---------- ------- ------------------- ----- ----
Gi1/0/48  auto   on         7.0     Ieee PD             2     30.0

Interface  AdminPowerMax   AdminConsumption
             (Watts)           (Watts)
---------- --------------- --------------------

Gi1/0/48              30.0                 30.0
aj-rcp-sw-b20002-r201-1# test cable tdr interface gig1/0/48
Link state may be affected during TDR test
TDR test started on interface Gi1/0/48
A TDR test can take a few seconds to run on an interface
Use 'show cable-diagnostics tdr' to read the TDR results.
aj-rcp-sw-b20002-r201-1#show cable tdr interface gi1/0/48
TDR test last run on: April 08 08:07:31

Interface Speed Local pair Pair length        Remote pair Pair status
--------- ----- ---------- ------------------ ----------- --------------------
Gi1/0/48  100M  Pair A     N/A                N/A         Not Completed
                Pair B     N/A                N/A         Not Completed
                Pair C     N/A                N/A         Not Completed
                Pair D     N/A                N/A         Not Completed
aj-rcp-sw-b20002-r201-1# test cable tdr interface gig1/0/48
Link state may be affected during TDR test
TDR test started on interface Gi1/0/48
A TDR test can take a few seconds to run on an interface
Use 'show cable-diagnostics tdr' to read the TDR results.
aj-rcp-sw-b20002-r201-1#show cable tdr interface gi1/0/48
TDR test last run on: April 08 08:08:37

Interface Speed Local pair Pair length        Remote pair Pair status
--------- ----- ---------- ------------------ ----------- --------------------
Gi1/0/48  100M  Pair A     N/A                N/A         Not Completed
                Pair B     N/A                N/A         Not Completed
                Pair C     N/A                N/A         Not Completed
                Pair D     N/A                N/A         Not Completed
aj-rcp-sw-b20002-r201-1#

[Leo Laohoo]

Ok. if you are getting "Not completed" and the TDR is done on a 2960 or 3750 then there's really something bad with your cable.  

Just to make sure, re-run the "sh cable tdr interface G1/0/48" command so you'll be able to isolate the distance of the cable fault.  

[tdennehy]

aj-rcp-sw-b20002-r201-1#
aj-rcp-sw-b20002-r201-1#sho power inline gi1/0/48
Interface Admin  Oper       Power   Device              Class Max
                            (Watts)
--------- ------ ---------- ------- ------------------- ----- ----
Gi1/0/48  auto   on         7.0     Ieee PD             2     30.0

Interface  AdminPowerMax   AdminConsumption
             (Watts)           (Watts)
---------- --------------- --------------------

Gi1/0/48              30.0                 30.0
aj-rcp-sw-b20002-r201-1# test cable tdr interface gig1/0/48
Link state may be affected during TDR test
TDR test started on interface Gi1/0/48
A TDR test can take a few seconds to run on an interface
Use 'show cable-diagnostics tdr' to read the TDR results.
aj-rcp-sw-b20002-r201-1#show cable tdr interface gi1/0/48
TDR test last run on: April 08 08:07:31

Interface Speed Local pair Pair length        Remote pair Pair status
--------- ----- ---------- ------------------ ----------- --------------------
Gi1/0/48  100M  Pair A     N/A                N/A         Not Completed
                Pair B     N/A                N/A         Not Completed
                Pair C     N/A                N/A         Not Completed
                Pair D     N/A                N/A         Not Completed
aj-rcp-sw-b20002-r201-1# test cable tdr interface gig1/0/48
Link state may be affected during TDR test
TDR test started on interface Gi1/0/48
A TDR test can take a few seconds to run on an interface
Use 'show cable-diagnostics tdr' to read the TDR results.
aj-rcp-sw-b20002-r201-1#show cable tdr interface gi1/0/48
TDR test last run on: April 08 08:08:37

Interface Speed Local pair Pair length        Remote pair Pair status
--------- ----- ---------- ------------------ ----------- --------------------
Gi1/0/48  100M  Pair A     N/A                N/A         Not Completed
                Pair B     N/A                N/A         Not Completed
                Pair C     N/A                N/A         Not Completed
                Pair D     N/A                N/A         Not Completed
aj-rcp-sw-b20002-r201-1#

[tdennehy]

I've been in this field for nineteen years now, and back in the early days I would just pull the plug, count to five and plug it back in.  I decided on Wednesday to reboot it at 2am and see how it goes.

After all, I had replaced the patch cords to eliminate bad copper.  Keep in mind that I was sitting in the network closet with a phone, not using the building's copper.  Then I brought in a different model of phone, and then two new, bagged patch cords.  Ports were truly dead.  My laptop would turn the port up, but that is about it.  No communication whatsoever.

After the reboot, the ports came back to life and all is good.  Of course I don't know why or how this happens - I suspect some sort of software flaw, obviously.  I didn't see the counters on the interface all reach some magic number and shut off.  There were input and output numbers, but they seemed random.

Short answer - REBOOT

[Leo Laohoo]

Hmmmm ... That is interesting.  

Could you tell me what IOS version your switch is running on?