Divide and Conquer: Partitioning OSPF networks with SDN

TL;DR

This paper introduces a hybrid SDN/OSPF approach that uses SDN nodes to partition networks into sub-domains, enabling effective traffic engineering without replacing existing OSPF protocols.

Contribution

It presents a novel method of using SDN nodes as domain borders to optimize inter-sub-domain routing while maintaining OSPF stability within sub-domains.

Findings

Few SDN nodes enable significant traffic engineering benefits.

The approach achieves near full SDN traffic management capabilities.

Simulation results validate the effectiveness of the partitioning method.

Abstract

Software Defined Networking (SDN) is an emerging network control paradigm focused on logical centralization and programmability. At the same time, distributed routing protocols, most notably OSPF and IS-IS, are still prevalent in IP networks, as they provide shortest path routing, fast topological convergence after network failures, and, perhaps most importantly, the confidence based on decades of reliable operation. Therefore, a hybrid SDN/OSPF operation remains a desirable proposition. In this paper, we propose a new method of hybrid SDN/OSPF operation. Our method is different from other hybrid approaches, as it uses SDN nodes to partition an OSPF domain into sub-domains thereby achieving the traffic engineering capabilities comparable to full SDN operation. We place SDN-enabled routers as sub-domain border nodes, while the operation of the OSPF protocol continues unaffected. In this way, the SDN controller can tune routing protocol updates for traffic engineering purposes before they are flooded into sub-domains. While local routing inside sub-domains remains stable at all times, inter-sub-domain routes can be optimized by determining the routes in each traversed sub-domain. As the majority of traffic in non-trivial topologies has to traverse multiple sub-domains, our simulation results confirm that a few SDN nodes allow traffic engineering up to a degree that renders full SDN deployment unnecessary.