Right now I am trying to troubleshoot an IP helper issue on our network. We have a provisioning system on one vlan (n)/subnet (opsware/HP System Automation), and the server to be provisioned on another separate vlan (30)/subnet. Between them we have two routers using HSRP. The routers have an IP helper configured for vlan 30, forwarding requests to the provisioning system.
We have verified that DHCP requests are being generated by the server. We have verified that the configuration looks correct for the vlan on the routers (in the vlan config, there is an ip-helper configured - there's not a lot complicated about that). We are working to verify that the provisioning system is not getting the dhcp requests, and that's where my question comes up...
When a router uses an ip-helper to redirect a broadcast as a unicast to the helper address, what MAC address is contained in the unicast? Is it the MAC of the router's outbound port, of the original host that generated the broadcast?
Sadly the routers handle a massive amount of traffic, so network engineering is unable to do a debug or packet dump off of the routers, so what's going on in there is currently a black box. At this point I'm working to gather as much evidence as I can to see where the issue lies.