ubun2

Hello,
I need to test the performance of some networking equipment. Essentially I would like to setup one PC with two ethernet cards. Essentially I am sending traffice from one NIC (IP) to the second NIC (IP).  The issue which I am having is that the Kernel is too smart and routes the traffic internally without even touching the network interfaces. How can I disable the local routing and force the computer to send the traffic over the network interfaces.
 
Some links relating to this questions are:
http://www.mail-archive.com/lartc@mailman.ds9a.nl/msg17423.html
http://ubuntuforums.org/showthread.php?t=722210
http://linux-ip.net/html/routing-tables.html
http://fixunix.com/networking/434407-disable-local-routing-between-eth0-eth1-iptables.html