Computer not receiving an ip address?

[Energize]

I've got a strange situation occurring when I try to relay DHCP requests through my Cisco 2801 router.

I have a router on a stick configuration with the networks 10.1.51.0 and 10.1.52.0 running on vlans 51 and 52 respectively, which works absolutely fine with static ip's or using the router as a dhcp server for each network, however when I disable dhcp on the router and run a dhcp server app on 10.1.51.200 the host on the 10.1.52.0 network can not get an ip address. My tftpd32 software on the server shows a dhcp request and ip address allocation so the server is clearly receiving and responding to the request, but the host isn't receiving this information and/or processing it correctly.

Where do I start troubleshooting this situation?

 

[the-evaluator]

That's exactly what I would expect to happen - you need something to relay the DHCP request from 10.1.52.0/24 to the DHCP server on 10.1.51.200. DHCP is broadcast traffic so it won't leave the VLAN without some assistance.

That assistance in Cisco speak is a helper address. If you were to configure a helper address of 10.1.51.200 on the interface on the C2801 that's in 10.1.52.0/24 then your DHCP requests will get through.

 

[Energize]

The DHCP request is being successfully relayed I have already executed the statement

int fa0/1.52
ip helper-address 10.1.51.200

10.1.51.200 is receiving the request from 10.1.52.50 and allocating an ip address.

 

[Caged]

Stick a port mirror on the port your device is attached to and do a Wireshark trace