Field Domain Segmentation Approach to Filter Encoding for Efficient Packet Classification with TCAM

D. Pao, P. Zhou, B. Liu (PRC), and X. Zhang (USA)


Ternary CAM, packet classification, filter encoding, prefix inclusion coding, domain segmentation, incremental update.


Filter encoding can effectively enhance the efficiency of TCAM-based packet classification. However, additional complexity will be incurred in the filter table update operations. It has been shown that the average update cost of the prefix inclusion coding (PIC) scheme is very low but the worst case update cost can be significantly higher. In this paper we shall present a domain segmentation approach to enhance the performance of PIC. By dividing the field value domain into multiple segments, the mapping of field values to code points can be more structural and help to avoid massive code-point relocation in the event of new insertions. Moreover, the codeword lookup for the address fields can be largely simplified and can be implemented in SRAM rather than using TCAM. The lookup rate of the search engine can be improved to handle 40Gbps OC-768 line rate.

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