Separating network control from routers with Software Defined Networking

Data networks have become increasingly complex nowadays. Even though technologies like Ethernet, IP protocol and packet forwarding is rather simple, control mechanisms like middleboxes, Access Control Lists (ACLs), firewalls, traffic engineering, VLANs, etc. have largely contributed to increasing their complexity. Primarily this is due to the lack of basic principles in networking. Networking still remains vertically integrated, where hardware comes with its proprietary software and is not open to innovation. Software-Defined Networks (SDN) instead decouple the data plane (which is and should remain the job of the physical routers) and control plane. The control plane in SDN is removed from the routers and switches, and instead is done in the edge of the network, thus allowing for third party software, open interface to devices regardless of hardware type and vendor, and easier management of networks. SDN is a new design model in networks rather than a new technology. It is a set of abstractions for the control plane rather than implementation mechanisms; SDN in essence offers the possibility to network programmers and third party app writers build anything they want on top of both router chips (data plane) and the Network operating system (now through OpenFlow, but it may be something else as well) in the control plane, as well as on top of the Network Operating system due to the open interface it introduces.