Efficient Gray-Code-Based Range Encoding Schemes for Packet Classification in TCAM

An efficient ternary content addressable memory (TCAM) encoding scheme using a binary reflected Gray code (BRGC) and the concept of elementary intervals is presented for efficiently storing arbitrary ranges in TCAM. The proposed layered BRGC range encoding scheme (L-BRGC) groups ranges into BRGC range sets in which each range can be encoded into a single ternary vector. The results of experiments performed on real-life and synthesized rule tables show that L-BRGC consumes less TCAM than all the existing range encoding schemes for all rule tables, except that the direct conversion scheme (EIGC) using elementary intervals and BRGC codes performs best for a small real-life ACL rule table.