Parsing application layer protocol with commodity hardware for SDN

The de facto implementation of Software Defined Networking (SDN), i.e., OpenFlow, only parses L2-L4 headers, which limits the use of SDN to employ control intelligence in application layer. In this paper, we advocate content parsing to empower SDN with finer grained control ability over traffic. Specifically, we propose a scalable content parser, called COPY, to identify and parse application layer protocols. COPY creates a distinguishable counting context free grammar (DCCFG) to specify the protocol's semantics in application layer, and translates multiple DCCFGs into one distinguishable counting automaton (DCA). DCA is generated without semantic loss from the single DCCFG, and thus provides accurate and scalable parsing ability. Our experiments show that COPY precisely identifies every packet in a labeled trace. When comparing with other six approaches on the real traces, COPY performs 4.2Gb/s and 24.7Gb/s with single- and eight-thread models, respectively, which improves 20%-860% than others, and consumes acceptable offline overhead in time and space.