Wildcard Rules Caching and Cache Replacement Algorithms in Software-Defined Networking

Abstract

In software-defined networking, flow tables of OpenFlow switches are implemented by ternary content addressable memory (TCAM). Although TCAM can process input packets in high speed, it is a scarce and expensive resource providing only a few thousands of rule entries on a network switch. Rules caching is a technique to solve the TCAM capacity problem. However, the rule dependency problem is a challenging issue for wildcard rules caching where packets can mismatch rules. In this paper, we use a cover-set approach to solve the rule dependency problem and cache important rules to TCAM. We also propose a rule cache replacement algorithm considering the temporal and spatial traffic localities. Simulation results show that our algorithms have better cache hit ratio than previous works.