DHCP server running locally on a 2960 switch. Polycom 450 phone trying to get an IP in the VoIP VLAN.
When the switchport configuration is set for an access port in the voice VLAN, the phone gets an IP and all is well.
When the switchport configuration is set to auto negotiate the voice VLAN, the phone does not get and IP address. The DHCP server behaves differently and although it sees the DHCPREQUEST come back, it decides to find a relay rather than sending a DHCPACK.
This started off with me troubleshooting a Windows DCHP scope - same symptoms, then I deactiveated the scope and built the DHCP server on the core switch, same symptoms, and finally, I moved the DHCP service to the same switch as the phone.
I tried both LLDP and CDP for VLAN negotiation. Both seem to place the phone correctly in the VoIP VLAN. I stopped and started the DHCP service.
The phone vendor is insistent that the issue is not with the phones and I tend to agree having deployed the same phones on Cisco switches serveral times.
Attached is the DHCP, switchport info, and DHCP packet and UDP traffic debug for the phone after the phone has been power cycled. Thank you for reviewing!
