Have the following problem at work in a large campus network, an access switch that is setup as a root bridge of that segment and vtp is set to client, but all users on that segment can access other vlan's except the voice vlan. The Cisco IP phones just get the time and date but does not log into call manager although I can ping both Call Manager and DHCP server from the switch. If I plug the Cisco phones on another segment the phones work perfectly fine. I even went to the extent of replacing the switch with a new one, after installing the new switch I noticed that my new switch changed from VTP client mode to VTP Server mode. I was absolutely shocked at this and I thought that I was about to overwrite all other vlans in that VTP domain.. I also forgot that mac-address was cleared and rebooted, I am also unable to ping the IP phones although I can see them if i do a show cdp neighbors detail.
Your assistance would be appreciated.
Most new switches are in VTP server mode by default. Having a null value as the VTP Domain, they should sync with the first advertisement that they receive. So I'm curious if you actually checked and saw the switch set to client mode. I'd be curious what the specifics were that seemed to be causing the grief prior to running a more direct cable. Could be an opportunity to understand your network a little better if you have the opportunity to work through the issue without the extra cable.