The Brief of Software Defined Networking

Hai. In this time, i'm gonna tell you about a sort brief of Software Defined Networking. If you wanna know depthly about this, you can read from this link, or you can download the paper in here.
Okay, here we go!

Road to SDN

Designing and managing networks has become more innovative over the past few years with the aid of SDN (Software Defined Networking). This technology seems to have appeared suddenly, but it is actually part of a long history of trying to make computer networks more programmable.

Computer networks are complex and difficult to manage. They involve many kinds of equipment, from router and switches to  middlebox such as firewalls, network address translator, servver load balancers, and intrutions-detection systems. Routers and switches run complex, distributer control software that is typically closed and proprietary. The software implements network protocols that undergo years of standarization and interoperability testing. Network admininstrators typically configure individual network devices using configuration interfaces that vary between vendors-and even between different products from the same vendor. Although some network-management tools offer a central vantage point for configuring the network, these system still operate at the level of individual protocols, mechanism, and configuration interfaces. this mode of operation has slowed innovation, increased complexity and inflated both the capital and the operational costs of running a network.

But SDN, is changing the way networks are designed and managed. it has two defining characteristic. First is SDN separates the control plane(which decides how to handle the traffic) from the data plane(which forwards traffic according to decisions that the control plane makes). And second is SDN consolidates the control plane, so that a single software control programe control multiple data-plane elements. The SDN control plane exercises direct control over the state in the network's data-plane elements (routers, switches and middleboxes) via a well-defined API. the Openflow is a prominent of such an API. An Openflow switch has one or more table of packet-handling rules. Each rule matches a subset of traffic and performs certain actions on the traffic that mathes a rule, actions include dropping, forwarding, or flooding. Depending on the rules installed by a controller app, an openflow switch can behave as a router, switch, firewall, NAT or something.

Although the excitment about SDN has become more palpable fairly recently, many of the ideas underlying  the technology have evolved over the past 20 years. In some way, SDN revisits ideas from early telepony networks, which used a clear separation of control and data planes to simplify network management and the deployment of new services. Yet, open interfaces such as Openflow enable more innovation in controller platforms and applications than was possible on closed networks designed for a narrow range of telepony services. In other ways, SDN resembles past research on active networking, which articulated a vision for programmable networks, albeit with an emphasis on programmable data planes. SDN also relates to previous work on separating the control and data planes in computer neworks.

That is SDN. Thank you for visiting my page.