Hybrid-SDN for packet transport: The horizontal split

Network operators are seeking for solutions to make their networks innovation-ready, as they intend to adapt transport networks more easily to continuously changing requirements. The emerging SDN concept and its related technologies are discussed widely in the industry as a promising tool-set in order to provide increased programmability for transport. However, the SDN concept itself, when applied to packet networks, creates a significant gap between traditional networking practice and solely centrally controlled SDN network. This paper focuses on a Hybrid-SDN approach, which is able to narrow this gap via a more natural split of local and remote control functions. The described horizontal split keeps the impact on network design and operation less revolutionary and therefore such a Hybrid-SDN approach could provide a more realistic introduction of SDN in real transport network scenarios.