2.2 Kernel, 2 NICs and External Loopback

Hi, We're running a 2.2 Kernel on an SMP machine that has 2 NICs in that has cable between the 2 -- the idea being having data sent out over one network card -- through a device for testing -- and back through the second network card: and NOT using the Loopback device. There is a patch available for 2.0.36 kernel which modifies arp.c and apparently works (i.e. sends the data physically over the network cable) -- we've tried frigging arp.c from the 2.2 source but this doesn't seem to work. Diagram: [eth0] --cable-- {device} --cable-- [eth1] Where eth0 and eth1 are in the same machine. Does anyone have a patch to enable this in the 2.2 kernels? Cheers, Kev