This problem actually occurs in the N/w layers. In case of ARP, a router has 2 IP's-one for the local ethernet and the other for the FDDI ring.SO to resolve the hosts exactly, physical addresses are quintessential. We can find various solutions for it such as using a proxy ARP and also to have a host immediately see the dest'n on a remote N/w and just send all such traffic to adefault ethernet address that handles all remote traffic.If you are confused, relax and take a chill pill