From a testing perspective, if a PC has 2 NIC's, each configured for a different subnet, does traffic actually cross the LAN since each unique MAC is represented by a unique IP according to its ARP cache? Would not the destination network need to be resolved by a router? I guess a better question would be, is there an application that could actually choose a specfic NIC on which to send traffic. Is there? Question is based on VM images and would like to create the least number of VM images as possible to simulate a network.