I have a 3750-48PS switch acting as a layer 2 with a few ports configured for voice and data. This layer 2 switch is connected to another 3750-24PS switch acting as a layer 3 switch and having the Vlan interface configured with the IP helper addresses for DHCP.
We tried to configured the switch as a switch trunk and encountered the following problem:
The phone and data work at the same time, but if the phone is rebooted it will not get an IP address.
switchport trunk encapsulation dot1q
switchport trunk native vlan 240
switchport trunk allowed vlan 220,240
switchport mode trunk
mls qos trust dscp
spanning-tree bpduguard enable
Any help is greatly appreciated.
I have this problem too.