We are experience random problems, when booting Windows PC's connected to Cisco IP Phones 7911: the PC is unable to get an IP address of the DHCP server.
If, after the PC finishes booting up, we perform an "ipconfig renew" the PC is able to get an IP address from the DHCP server.
The DHCP server is the Catalyst 6500 core switch-router, and when the PC is booting up we see no DHCP request reaching the Catalyst 6500.
We have no problems when the PC is directly connected to the access switch (Catalyst 3560), instead of being connected through the Cisco IP Phone.
The IP Phones configuration, on the CallManager, have the "Forwarding Delay" set to disabled.
Here is the configuration of the switch port:
switchport access vlan 10
switchport mode access
switchport access vlan 4
mls qos trust device cisco-phone
mls qos trust cos
It seems as if the Cisco IP Phone internal switch is not implementing Spanning-tree PortFast functionality on the 10/100 PC port.
Anyone has seen this happen?