Cisco 7920 cyclic reboot

[garysoucy]

So, I saw a situation yesterday where the phone continually bounced when plugged into a switch with 2 other devices. Let me be a little more clear:

Network > Cisco 7920 (I think not entirely sure of the model) > Linksys 8-port switch > Docking Station AND PC in the switch, as well.

If just the laptop is on the docking station and the PC is off, the phone works fine. If just the PC is on and the laptop is off, the phone works just fine. If both PC and Laptop are on, the phone goes into a cyclic reboot. So, it boots, looks for network informaion DNS, VLAN, etc... and then the screen blanks and it starts over. Anyone have any ideas?

Thanks!

[paolo bevilacqua]

Check and report exact phone type, fimrware used. As well as call manager type and version.

[garysoucy]

Thanks for your quick response!

I will try to do this. However, it was at a remote site and I am not sure when I (or someone else who could do this) will be back there. Should be no later than towards the end of next week, however. Also, I will not have acces to the CM. I am trying to get in communication with their IT people, but haven't had any luck as of yet.

[s_mcnally]

To the OP, did you ever find anything out further about this issue.  I know its a bit old, but I am running into a similar issue with USB docking stations causing 7975s and 9971s to unregister and they don't recover.  Been chasing my tail on this one for a while.  Wireshark doesn't seem to point out anything obvious other than it seems like numerous TCP retrans or dup acks seem to occur (between the computer IP and the destination) just before the phone reboots. 

[garysoucy]

I did find an answer, and I apologize for not posting it. Turns out that port security is on on the switches we were connected to. It was a client's site and I now kick myself for not picking up on it. But because the phone and pc/laptop have different MAC addresses, only one was allowed. So putting a switch on that port, plugging multiple devices into it, just caused it to shut down. You may want to check out port security. In this case, it was set to shut down if more than one MAC address was trying to get into it. Good luck.

[s_mcnally]

Thanks for the response.  I wish it was port security killing the port with my issue.