Software defined networks Essay

Software defined networks, as defined by the Open Networking Foundation, are The physical separation of the network control plane from the forwarding plane, and where a control plane controls several devices. In simpler terms, this means that the network can be set up and managed through a centrally located program instead of a distributed system. The way in which SDNs do this is by making a program become a virtual switch or router and then direct the network traffic. Normally routers have preinstalled software whereby all of the signals are directed. OpenFlow and another similar protocol will be discussed in more detail later in the report, but for now it can just be thought of as the protocol in which the SDN application can access the forwarding plane of a switch through the network. The purpose of SDNs is not necessarily to speed up a network, but to make the network more easily scalable and manageable. Instead of having to update the settings on many different hardware components, a network administrator can essentially update a centrally located program.

In order to have a better understanding of SDNs today, it is good to know how it came about. In the early 1990s, networking researchers had a desire to make network control reprogrammable much like the way standalone computers are reprogrammable. There was also a drive among the network researchers to create alternatives to the prevailing 90s internet technology such as the internet protocol or asynchronous transfer mode. Through these goals, the first step toward SDNs were taken in the implementation of active networking. Active networking was used by telephone companies primarily, and it allowed packets flowing through a network to modify the network while in transit. Active networking was essentially the forefather of todays software defined network. The primary difference is that with active networking, the focus is on the programmability of the dataplane while the SDN focuses primarily on the programmability of the controlplane. The Defense Advanced Research Projects When discussing SDNs, there is much talk about the decoupling of the control plane from the forwarding plane. To make these terms more clear, a brief introduction to the different planes of a network will be needed. Network devices are said to have two primary planes that they operate on the control plane and the data plane. A third plane, the management plane, is sometimes included but for our purposes we will just discuss the control and data plane. The control plane is where a device learns about its surrounding network, such as what other devices are connected to it. Connection management, network design, and forwarding and routing decisions area also accomplished through this plane. The next plane, the data plane, is where the actions that were decided in the control plane are executed. Things such as the forwarding table, routing table, and address resolution protocol tables are located in the data plane. The data plane can also be referred to as the forwarding plane and the terms are interchangeable.