The network OS: Carrier-grade SDN control of multi-domain, multi-layer networks

Driven by the growth of cloud and virtualization technologies, telecom services are under pressure to become increasingly dynamic. Cloud services can be instantiated in a matter of minutes on computing platforms, which can rapidly schedule and allocate virtualized physical resources. A similar flexibility to adapt to dynamic service requests remains a challenge with network resources. Recently, centralized controllers have been deployed in data center networks to adapt network connectivity to computational needs. However, due to the complexity and variety of carrier networking technologies, carrier networks have been slow to move towards centralized control. More recently, carriers are evolving to address network complexity by pushing for the disaggregation of network elements and the introduction of equipment with more control flexibility. Carriers require a new control paradigm to benefit from this new flexibility, which extends far beyond today's OpenFlow network controllers. The lack of a global network controller with a consistent network view slows down the development and deployment of the more dynamic network services required by extensive cloud technologies. To address the scaling requirements of the carrier environment, the envisioned network controller would be implemented as a distributed system. In this article, we describe a global network controller designed to function as a network operating system with multi-domain, multi-layer capabilities that will transform carrier-grade telecom services. We define the requirements for a carrier-grade network operating system (OS) and describe a prototype system (NetUNIX) that can control heterogeneous networks at large scale and ensure high service reliability. We highlight the advantages of the NetUNIX platform in the context of other open source platforms and illustrate the use of the NetUNIX platform with two use cases: a metro-distributed data center and 5G next-generation fronthaul.