I have a problem with IOS DHCP client (this is an 800 series, but I've seen this issue before on a different platform).
Here's the situation:
- Server: ISC DHCPD (FreeBSD), vlan A
- Client: IOS 12.4(22)T1, VLAN B
client --> distribution switch == > core switch <== rack switch <-- server
- Core switch: SVIs for all VLANs, helper address set to the dhcp server, also forwarding udp bootpc/bootps
- DHCP snooping enabled on all switches on the way from client to server,
- Inserting option 82.
Note: disabling dhcp snooping and / or option 82 doesn't help.
Now, when I put the 800 series on the same VLAN as the DHCP server, I get the lease without any problems. But as soon as I move the 800 series onto any other VLAN, I can't get a DHCP lease. I can see it sending DHCPDISCOVER to the server and the server replies with a DHCPOFFER, but I see no DHCPACK.
There are more than 500 nodes on the network and none of them are experiencing any DHCP problems. Only Cisco devices have issues (that 800 series, but also saw this with other models).
Does this issue sound familiar to anyone? Could this actually be the server's fault? For whatever reason the server doesn't send DHCPACK - but only when not on the same VLAN as the client.