I have attempted to implement DHCP snooping and have been having some strange issues. I have 5 3560s taht I use for my edge and when I attempt to implement on all five, the VLAN that houses my voice data appears to no longer be able to recieve DHCP lease renewals so after the 24 expiration all of my phones lose their configs. Once I roll back the changes the voice VLAN comes back. The other VLANs seem to function correctly as theya re able to renew their DHCP addresses.
The 3560s tie into each other using GIG Ports 1 & 2 and the top and bottom switches tie into our core switch, a 4507. The config that I use is below, failry simple and straightforward.... I think?!?!?!
!
ip dhcp snooping vlan 1,2,3,etc.
ip dhcp snooping
!
interface GigabitEthernet0/1
description TRUNK to Core Switch
switchport trunk encapsulation dot1q
switchport mode trunk
ip dhcp snooping trust
!
interface GigabitEthernet0/2
description TRUNK to Core Switch
switchport trunk encapsulation dot1q
switchport mode trunk
speed 1000
duplex full
ip dhcp snooping trust
!
4 of the 5 switches feed our general office vlans for voice and data however the 5th switch is there for expansion and not in use. As such I have left the config changes in place on it and have tied myself and a colleague into it and have been operating fine for over a week now. So the config that I use seems sound in theory and should work on the other 4 switches with no issue.
I'm left scratching my head on this but can't understand what it is that I am missing. Any suggestions/advice would be helpful as I'm not sure how to proceed.
