Networks are messy. Although they can be made to look neat and tidy by holding all the gear in rack mounted cabinets with serious cable management makeovers, they are still comprised of small islands of hardware each running its own proprietary software and firmware, often on proprietary silicon. For home users this isn’t really an issue, but for large government and business networks things get complicated and convoluted quickly. Especially in the case of internal networks used by governments that need to be as locked down as possible, changing even one switch, server, or connected device on the network is a tedious (and expensive!) process of rewriting security rules on a each and every hardware device.
Each hardware device (be it a switch, router, server, or firewall) operates as its own isolated island which requires individual configuration. Seeing the shortcomings of such a setup, researchers and startup companies like Nicira have started to develop open software control systems under a coined term of “software defined networking” (SDN). Stuart Miniman defines SDN as “a model for network control, based on the idea that network traffic flow can be made programmable at scale, thus enabling new dynamic models for traffic management.” Similar to the way virtualization can be used to host many (virtual) computers on one physical piece of hardware, these virtualized networks could allow companies to run multiple network slices off of a single physical network.
This is a level of control and programmability that is not currently possible due to network hardware vendors using proprietary software in all their devices (Cisco’s IOS for example). SDN takes the proprietary code out of the equation, and — using open software on all the routers, switches, firewalls, and other network devices — separates the data and control planes (the packets and the logic that determines what to do with those packets). The network hardware is then connected and mapped out in software, and network admins are able to manage the entire network from a software interface. They are also able to specialize their network and add new functionality by writing their own code and deploying it across the network.
One of the most important benefits of SDN is that commodity hardware can be used, instead of specialty hardware from specific manufacturers. Removing or relocating devices on the network would involve a few mouse clicks in a GUI rather than physically switching Ethernet cables and reconfiguring all the appropriate network devices. Martin Casado, CTO of Nicira (who is one of the companies developing SDN technologies) said that “we’re virtualizing away this physical fabric, and because now we have a virtual layer, you can do anything you want with it. Because of this virtualization, the network can be fashioned from any and all compatible hardware, and can be controlled, transformed, and secured from a software interface rather than from configuring each device individually.
There is talk around the web that SDN will spell the end for special network hardwar companies like Cisco as well as eliminate the jobs of network operators. While entirely possible, such an event is not going to happen overnight. Cisco is not likely to give up without a fight, and at this point it still has a chance to react and adapt to this new technology. The reduction in network operator IT positions is possible as well but this virtualization technology is going to open up its own field of study as well, which should lead to positions maintaining SDN. Especially while software defined networking is still a new technology, businesses are going to need their IT personnel.
Networking giant Cisco has recently responded to rumors of SDN killing its business by stating that some customers do not want programmable networks. Also, for those customers that do want the flexibility of SDN, it has funded and plans to acquire network startup company Insieme. Insieme is reportedly working on a line of programmable network switches that support OpenStack as the SDN abstraction layer. The CTO of Cisco has been quoted by Network World in stating “Networking is about to be reinvented and Cisco will do that reinvention of networking.”
In the end, the idea of a truly modular virtualized network that allows control from a software GUI is really cool. It is a big shift in networking to a programmable, open, and modular network controlled via software software that will make managing large scale networks much easier.