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OpenFunction: An Extensible Data Plane Abstraction Protocol for Platform-Independent Software-Defined Middleboxes

The data plane abstraction is central to software-defined networking (SDN). Currently, SDN data plane abstraction has only been realized for switches but not for middleboxes. A data plane abstraction for middleboxes is needed to realize the vision of software-defined middleboxes (SDMs). Such a data plane abstraction should be both platform independent and fully extensible. The match-action abstractions in OpenFlow/P4 have limited expression power to be applicable to middleboxes. Modular abstraction approaches have been proposed to implement middlebox data plane but are not fully extensible in a platform-independent manner. In this paper, we propose OpenFunction, an extensible data plane abstraction protocol for platform-independent software-defined middleboxes. The main challenge is how to abstract packet operations, flow states, and event generations with elements. The key decision of OpenFunction is: actions/states/events operations should be defined in a uniform pattern and independent from each other. We implemented a working SDM system including one OpenFunction controller and three OpenFunction boxes based on Netmap, DPDK, and FPGA, respectively, to verify OpenFunction abstraction.