Published 15 November, 2013
Have you heard of “the Cloud”? Of course you have. Almost all kinds of services are now being offered as “cloud services”, meaning services using data storage and processing power of Internet-connected server farms rather than running in a computer on your desk or in a server room at your company. Like a déjà-vu from the thin clients of the 1980s, your computer becomes a hollow work station, with Office software and hard drive in “the cloud”.
Now comes the next step in this evolution: networking hardware is also stripped of their intelligence, submitting themselves to control from a central unit. We are used to seeing networks built from routers and switches, and maybe even an occasional hub, and it is of utmost importance to make the right design choices, deciding where to put routers and where to put switches. What if you could turn a switch into a router by the press of a button? Exactly this is the essence of “Software Defined Networking” or SDN. The building blocks are standardized protocols for configuration and maintenance, and network components supporting these protocols. Central nodes control the network components, thereby separating logic from hardware.
One advantage of this is that we gain a huge amount of flexibility. Another is that the “stupid” network elements are well-nigh identical to each other, making them cheaper and more robust. We also get vendor-independent networks, as the network elements don’t contain any logic, only obeying standardized commands, therefore letting us easily switch them for hardware of other vendors. We end up with networks where functions such as DiffServ, VLAN and MPLS are only configurations in the logic of the control node – Simple!
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