Software-Defined Network. How it works and how to deploy. Part 1

Since the arrival of the Internet, IP networks have become increasingly important, and are now the hub of all services far beyond the scope of those initially offered by the Internet (Web, e-mail, news, etc.). However, IP technology and equipment have had to adapt to the constraints of new services (voice, video, etc.) requiring service guarantees, whereas IP was originally a protocol with no guarantees. Equipment has also had to adapt to cope with increasing bandwidth (today we're talking about 100 Gbps links, and soon 400 Gbps) and the continual need for new functionalities.

At the start of the twenty-first century, we are entering the era of all-IP, with the gradual disappearance of other types of network (ATM, Frame-Relay, Switched Telephone Network, etc.).

This move towards all-IP means supporting more and more services, with increasingly complex architectures, on more and more varied equipment, requiring more and more functionality.

Customers are also looking for increasingly flexible and customizable services, which must be available very quickly after subscription.

With the advent of the Cloud and the hosting of services in data centers, interconnection issues with third-party networks are also taking on even greater importance. The dynamic behavior offered by the Cloud must therefore also be pursued at network interconnection level.

Even if the IP network becomes the core of all services, we must not forget the transport infrastructure. Transmission networks (OTN, WDM) will also have to adapt to the needs of the IP layer.

In this article, we'll start by reviewing the history of IP networks to understand their evolution. This will enable us to understand current limitations and introduce the need for programmable networks via SDN techniques. We will then analyze two initial SDN use cases: WAN connection optimization and equipment configuration automation.

In a second article, [TE 7 611] , we'll be taking a closer look at other SDN use cases and their implementations, and presenting some of the most popular technologies.