SDN Partitioning: A Centralized Control Plane for Distributed Routing Protocols

TL;DR

This paper introduces SDN Partitioning, a method that combines centralized SDN control with distributed routing by partitioning the network topology, enabling dynamic traffic steering while maintaining the simplicity of OSPF.

Contribution

It proposes a novel topology partitioning scheme that balances centralized control and distributed routing, enhancing network management and traffic control capabilities.

Findings

Significant performance improvements over legacy protocols.

Small sub-domains achieve control comparable to full SDN.

Flexible partitioning allows trade-offs between control and simplicity.

Abstract

Hybrid IP networks that use both control paradigms - distributed and centralized - promise the best of two worlds: programmability and agility of SDN, and reliability and fault tolerance of distributed routing protocols like OSPF. The common approaches follow a division of labor concept, where SDN controls prioritized traffic and OSPF assures care-free operation of best effort traffic. We propose SDN Partitioning, which establishes centralized control over the distributed routing protocol by partitioning the topology into sub-domains with SDN-enabled border nodes, such that OSPF's routing updates have to traverse SDN border nodes to reach neighboring sub-domains. This allows the central controller to modify how sub-domains view one another, which in turn allows to steer inter-sub-domain traffic. The degree of dynamic control against simplicity of OSPF can be trade off by adjusting the size of the sub-domains. This paper explains the technical requirements, presents a novel scheme for balanced topology partitioning, and provides the models for common network management tasks. Our performance evaluation shows that - already in its minimum configuration with two sub-domains - SDN Partitioning provides significant improvements in all respects compared to legacy routing protocols, whereas smaller sub-domains provide network control capabilities comparable to full SDN deployment.