An advanced data structure allows lookup based upon the most significant 16 bits and the following variable number of K bits of the IP destination address. This 16/K scheme requires less than 2 MB memory to store the whole routing tables of present day backbone routers. A 16/Kc version utilizes bitmaps...http://www.google.de/patents/US20020172203?utm_source=gb-gplus-sharePatent US20020172203 - Fast IP route lookup with 16/K and 16/Kc compressed data structures
