MDTC: An efficient approach to TCAM-based multidimensional table compression

Ternary Content Addressable Memory(TCAM)-based multidimensional tables are widely used to implement Access Control Lists (ACLs) for Internet packet classification and filtering, and have also become attractive for constructing the forwarding tables of Internet routers and the flow tables of Openflow switches, where multiple fields are generally used to match incoming packets. However, as such tables can grow quickly as the Internet develops fast, and sometimes even expand in size because of TCAMs limitation in storing rules with range fields, it becomes imperative to compress these tables. In this paper, we propose a fast and efficient approach to multidimensional table compression. We divide the multidimensional space iteratively to obtain a series of cells, and then combine those cells that are associated with the same action. Our approach applies to tables of any dimension, addresses the range expansion problem, and provides efficient compression for TCAM-based tables. The experiments show that our approach has low computing cost in time, which is significant for the online update of tables. On average, it reduces 23.0% entries of the real-life ACLs, 25.8% to 55.1% of the generated two-dimension tables, 55.1% of the generated ACLs, and 28.4% of the generated Openflow flow tables.