For some years now, the network operator industry has been going through an evolutionary period of major technology developments with the creation of Cloud technologies, Software-defined Networking (SDN), Network Functions Visualisation (NFV), Big Data and Next Generation Operations Support Systems (Next Generation OSS). These key innovative technologies target at reducing complexity and controlling service delivery for the network operator, and aim to bringing greater flexibility, agility and simplicity into the network operator environments. The primary focus of these technology developments is to solve the business problems that are constraining the network operators, and to open up new revenue opportunities. Although they are not as silo-based as historic solutions, they still have the need to be architecturally integrated to create a flow through automated business-focused architecture. As network operators achieve revenue by enabling their services over a network infrastructure, the activation, control and management of the service and infrastructure is primary to the business model they operate. SDN sits between the higher-level applications/technologies and the network elements. SDN takes the generalised business logic and abstracts it into the network elements with the purpose of initialising the service on the network infrastructure. In addition, it enables the APIs from the network elements to communicate greater analytics, therefore ensuring that the higher-level applications can drive enhanced service management and control for the benefit of the customer. This is done with the aim of creating greater efficiencies in the operating model of the network operator. With SDN being the enabler technology between the network infrastructure and the higher-level service and business logic applications, SDN can therefore be identified as being the technology which unifies these other innovative technologies for the driving forward of the network operators' business goals. Many in the industry already believe that SDN is the future of networking. The author believes that SDN can achieve much more. This is based upon work done over the last nine years that has been targeted at creating a new architectural business approach. The purpose of this book is to share information on how SDN can be used to bring together the multiple new technology developments and to suggest how a new architectural approach can be defined. Change always impacts the entire organisation; it requires investment and creates work. This book describes a strategic end-to-end approach that allows network operators to kick off their evaluation of SDN by investigating available solutions that address key problem areas within their organisation. This way, companies when they have identified the real business drivers to change, can start implementing at a small scale and evolve the technology into their environments. Through this approach lessons can be learnt, and the companies can develop their business-focused technology strategy over time, through experience. This allows for the strategic approach to be communicated throughout the organisation and for the value to be seen by the people within the organisation, therefore minimising disruption and impact to on-going day-to-day business. This book is not definitive - but has been written to highlight how the evolving technologies can be brought together under a unified and flexible architectural approach. As few companies operate the same business model or have the same targets and goals, the SDN Strategic Architecture aims to enable architects, solutions designers, developers, operations staff, product teams and engineers to identify how they can create a flexible architecture which is specific to the targets and goals of their individual company's business plan.