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, TCAM has four shortcomings, TCAM capacity, power consumption, heat generation, and board space problems. Rules caching is a technique to solve the TCAM capacity problem which is the most important problem in TCAM. However, the rule dependency problem is a challenging issue for wildcard rules caching where packets could mismatch rules. In this paper, we use cover set to solve rule dependency problem and cache important rules to TCAM. Instead of calculating contribution value of an individual rule, our wildcard rules caching algorithm calculates contribution value of a set of rules. Besides, we propose a cache replacement algorithm considering the temporal and spatial traffic localities. Simulation results show that our caching algorithm could get 10% average improvement ratio than previous work. Cache replacement algorithm could get 12% and 17% higher cache hit ratio than least recently used and random replacement algorithms, respectively.