HBD: towards efficient reactive rule dispatching in software-defined networks

Most types of Software-Defined Networking (SDN) architectures employ reactive rule dispatching to enhance real-time network control. The rule dispatcher, as one of the key components of the network controller, generates and dispatches the cache rules with response for the packet-in messages from the forwarding devices. It is important not only for ensuring semantic integrity between the control plane and the data plane, but also for preserving the performance and efficiency of the forwarding devices. In theory, generating the optimal cache rules on demands is a knotty problem due to its high theoretical complexity. In practice, however, the characteristics lying in real-life traffic and rule sets demonstrate that temporal and spacial localities can be leveraged by the rule dispatcher to significantly reduce computational overhead. In this paper, we take a deep-dive into the reactive rule dispatching problem through modeling and complexity analysis, and then we propose a set of algorithms named Hierarchy-Based Dispatching (HBD), which exploits the nesting hierarchy of rules to simplify the theoretical model of the problem, and trade the strict coverage optimality off for a more practical but still superior rule generation result. Experimental result shows that HBD achieves performance gain in terms of rule cache capability and rule storage efficiency against the existing approaches.