Efficient TCAM Encoding Schemes for Packet Classification Using Gray Code

Packet classification is an enabling function in Internet routers for a variety of Internet applications. In order to classify Internet packets into flows, Internet routers must perform searches over a set of filters using multiple fields of the packet as the search key. Because of its speed and simple filter management the Ternary Content Addressable Memory (TCAM) is currently the dominant hardware solution for IP lookups, i.e., a one-dimensional packet classification. To make TCAM the solution for the multi-dimensional packet classification, efficient methods that store the range fields of the classification tables in TCAM are needed. In this paper, we propose a set of novel range encoding schemes based on Gray code. Many range-encoding techniques are used to improve the existing elementary interval- based range encoding schemes. The present experiment´s results show that the proposed Gray code-based schemes consume less TCAM storage space than the existing schemes.