On the Problem of Optimal Path Encoding for Software-Defined Software Networks
Abstract: Packet networks need to maintain the state in the form of forwarding tables at each switch. The cost of this state increases as networks support ever more sophisticated per-flow flow routing, traffic engineering, and service chaining. Per-flow Per or per-path path state at the switches can be eliminated by encoding each packet's desired path in its header. A key component of such a method is an efficient encoding of paths through the n network. etwork. We introduce a mathematical formulation of this optimal path path-encoding encoding problem. We prove that the problem is APX-hard, hard, by showing that approximating it to within a factor less than 8/7 is NPNP hard. Thus, at best, we can hope for a constant constant-factor approximation roximation algorithm. We then present such an algorithm, approximating the optimal path-encoding path problem to within a factor 2. Finally, we provide the empirical results illustrating the effectiveness of the proposed algorithm.