SDN based traffic engineering without optimization: A centrality based approach

Software defined networks (SDNs) reduce the complexity of implementing multi-commodity flow (MCF) optimization problems and several optimization based SDN Traffic Engineering (TE) schemes have been proposed. This approach has several limitations like the need to know or infer bandwidth demands, the number of forwarding rules needed to implement the solution and the cost of the control-loop communication between controller and switches. This usually results in systems that do not scale and need to adapt the problem formulation to an approximation of the optimal solution. In this work we propose an approach for TE in SDNs without optimization and no need for traffic demand knowledge. We propose a logically hierarchical controller architecture built on the premise of low rule space and sparse controller communication where TE is performed in two actions: the setting of stable paths in the core and the distribution of traffic among them in the access. Different algorithms can be used for these purposes. We start by studying the performance of using a shortest path algorithm for the calculation of the stable core paths and a concept from social networks analysis called betweenness centrality to measure congestion risk and support the traffic distribution decisions in the access. 1