Author(s): S. Sezer, S. Scott-Hayward, P.K. Chouhan, B. Fraser, D. Lake, J. Finnegan, N. Viljoen, M. Miller, and N. Rao
This paper appears in: IEEE Communications Magazine
Issue Date: July 2013
Cloud services are exploding, and organizations are converging their data centers in order to take advantage of the predictability, continuity, and quality of service delivered by virtualization technologies. In parallel, energy-efficient and high-security networking is of increasing importance to network operators. Software Defined Networking (SDN) has emerged as an efficient network technology capable of supporting the dynamic nature of future network functions and intelligent applications while lowering operating costs through simplified hardware, software, and management. This article addresses the question of how to achieve a successful carrier grade network with SDN. Specific focus is placed on the challenges of network performance, quality, scalability, security, and interoperability with the proposal of potential solution directions.
Today network configuration and installation requires highly skilled personnel adept at configuration of many network elements. Where interactions between network nodes (switches, routers, etc.) are complex, a more systems-based approach encompassing elements of simulation is required. With the current programming interfaces on much of today’s networking equipment, this is difficult to achieve. In addition, operational costs involved in provisioning and managing large multivendor networks covering multiple technologies have been increasing over recent years, while the predominant trend in revenue for operations has been decreasing. Coupled with increasing scarcity of human resources and increasing costs of real estate, this “perfect storm” for service providers is leading to renewed interest in solutions that can unify network management and provisioning across multiple domains. A new network model is required to support this.
In this article, SDN is described with the Open Networking Foundation (ONF)  definition: “In the SDN architecture, the control and data planes are decoupled, network intelligence and state are logically centralized, and the underlying network infrastructure is abstracted from the applications.”
The authors’ vision of the future SDN architecture encompasses the complete network platform with separation of the control and data planes, and maintaining carrier grade service. The architecture requirements to meet operational expectations in carrier grade networks are scalability, reliability, quality of service (QoS), and service management. The article contains a good discussion on control-data plane separation challenges. The article also contains a good discussion on how to achieve a programmable switch, and concludes with the outline of a vision for the future of SDN/NFV.