Internet protocol address look-up method

An Internet Protocol address look-up method for looking up an Internet Protocol address of an Internet Protocol packet in order to forward the Internet Protocol packet, the method comprising:

• inputting a search key into a plurality of routing entries, the search key corresponding to a destination address of an Internet Protocol packet to be forwarded, each one of the respective routing entries having a data string that includes a respective prefix and having a mask string that represents length of the respective prefix, each one of the routing entries being included in a ternary content addressable memory (CAM);
• detecting matching prefixes when the search key matches prefixes from among the prefixes of the routing entries;
• outputting the mask strings corresponding to the routing entries having the matching prefixes;
• assigning an upper pointer to a most significant bit of the outputted mask strings;
• assigning a lower pointer to a least significant bit of the outputted mask strings;
• assigning a check pointer to a bit of the outputted mask strings intermediately positioned between the upper and lower pointers;
• when more than one bit indicated by the check pointer corresponds to a prefix bit, reassigning the lower pointer to a new position corresponding to the position of the check pointer and then reassigning the check pointer to a bit of the outputted mask strings intermediately positioned between the upper pointer and the reassigned lower pointer;
• and
• when only one bit indicated by the check pointer corresponds to a prefix bit, determining that a longest prefix matching (LPM) entry corresponds to the outputted mask string having the one bit indicated by the check pointer, the longest prefix matching entry corresponding to the routing entry having the longest outputted mask string.