We have a problem with several Cisco IP Phones CP-7941G and the Video Advantage Software. The phones are running the SCCP41.8-3-3SR2S firmware but problem exists also with the SCCP41.8-3-3S firmware.
As far as I can see the phone does not send out CDP packets on the PC switch port. Within CSCsk11000 an error in the CDP implementation is described for the firmware version SCCP41.8-3-2SR1S.
Attached you find Wireshark Sniffer File describing the issue. A capture filter limiting the traffic source to the phone was applied.
Here are some comments what happened outside the wire:
3 The phone was restarted to enable the settings access. It was then assured that not only in the Phone configuration on the CallManager (Version 6.01) CDP on the PC port was enabled but also on the phone itself. As you can see there are no CDP packets. Within the Video Advantage Software there is no connection between the phone and the camera.
4 The phone was reset. CDP packets are sent out immediately.
22 or 23 Within the Video Advantage Software the phone is connected to the camera.
In all our investigated cases a reset of the phone while the Video Advantage Software is running was successful.