On Conflict Handling in Software-Defined Networks

Abstract

Software-defined networks (SDN) allow the centralization of the network control plane into a platform for applications implementing network functions. Thus, SDN applications can replace the network appliances common in traditional networks with centrally deployed software packages. In addition, they are able to introduce the network function they implement into any element in the network topology. The greatly increased flexibility of SDN renders them more prone to conflict, i.e. interference between network functions. A demonstration of conflicts between SDN applications occurring even in a small laboratory setup indicates that conflict handling is indispensable in large-scale networks. We regard conflict detection as an obvious prerequisite for any further conflict handling, such as conflict classification and conflict resolution. With the aid of a program execution model for SDN we argue that a purely analytic approach to general conflict detection is infeasible and propose an experimental approach. We present an experimental methodology and develop a parameter space for the exhaustive, automated search for conflict situations in a large number of network scenarios. We show the parameter space for n-node networks to be of size of 10^n single experiment points and discuss alternatives to reduce its complexity to a manageable level.