Software Defined Networking: Time to Unshackle the Network

Jennifer Artley, COO, BT Americas

It’s been said that “software is eating the world”. Internet-based cloud platforms such as Amazon Web Services (AWS) and Microsoft Azure are indeed disrupting industries from the ground up. Public cloud services give startups that are unencumbered by legacy infrastructure, ways to develop and deploy new applications with unprecedented speed, flexibility, and efficiency. For many large enterprises, however, deploying new IT services in on-premise IT infrastructure is anything but fast, agile, and efficient. Fortunately, that is changing as traditional hardware-based networking is being “eaten” by software too. Indeed, Software Defined Networking (SDN) is an architecture that gives enterprises the power to radically simplify their network, making it easier to manage, and allowing applications to be deployed in minutes, rather than days.

  ​With SDN, the entire infrastructure, including servers, storage, and networking can be seen and managed as a single integrated entity. 

SDN has its roots in a number of research initiatives that sought to separate or abstract the control and management functionality of a networking device. The Internet Engineering Task Force, for example, created the ForCES (Forwarding and Control Element Separation) protocol in 2003 which separated the forwarding and control functionalities within a network device. Two years later a team at Stanford University launched the Clean Slate project with the idea of building a networking switch from scratch. Here the goal was to build a centralized control and management system that would look at the network as a whole in making its forwarding and routing decisions (as opposed to distributed device configurations running the show).That project led to the launch of the Open Networking Lab, a non-profit entity supported by industry that is actively promoting SDN as the means to boost Cloud innovation.

A traditional network is typically set up using hardware-based networking devices such as switches and routers. While new protocols have certainly made networking more efficient over the years, the basic design and implementation of such networking devices has not changed fundamentally over the past 20-25 years. Each device typically has its own data plane (responsible for forwarding traffic), control plane (responsible for controlling traffic), and management plane (responsible for managing the device). This means that each component has to be configured individually, with all the implications thereof on network management and flexibility.

SDN virtualizes and thus decouples the control and management functionality from the device and centralizes that functionality as a purely software-based service. That simplifies the network hardware, making it more cost effective and also creating a single plane for configuring, controlling, and managing the whole network.Therefore, if you want to deploy new services you do not need to reconfigure individual components. You simply define policies that are automatically pushed to components. It basically eradicates the “stovepipe” approach in deploying IT services, whereby each deployment has to work through a series of manual, error-prone, and often bureaucratic processes.

SDN within the enterprise is especially relevant for large companies that have their own network and datacenter, supporting a complex and, most importantly, dynamic business operation. These companies frequently need to deploy new resources and applications, but it is a time consuming and cumbersome process, especially from a governance perspective.

For example, BT is currently working with a large international customer that had three separate environments in its data center for production, development, and testing. These environments were separated to reduce the risk that development and testing could infringe on the production environment. Also, the deployment of new applications typically took weeks, undergoing several steps before these could be securely integrated in the network. Governance issues and the allocation of engineers to each of these steps created unavoidable delays.

With SDN, the entire infrastructure, including servers, storage, and networking can be seen and managed as a single integrated entity. New applications and their required resources can now be rolled out in minutes.

A migration to SDN does require new infrastructure since network components will need to be replaced with SDN-enabled technology. During the migration you will need to run two systems concurrently.This setup allows for smooth migration from an existing network environment to the SDN enabled Virtual Private Cloud.

As a whole, SDN allows you to utilize your IT infrastructure more effectively when compared to a classic hardware-defined architecture. Moreover, you can now model your IT infrastructure to suit your changing business needs, and do so without having to change your underlying network infrastructure. That improves your business agility, and at the same time reduces your total cost of ownership. Finally SDN allows for the seamless integration of services like firewalling, load-balancing, and the ability to automate and orchestrate end-to-end deployment of applications.