Some of you may have heard some new networking acronyms lately. SDN is perhaps the most common of these and it is something that is going to change the way the Internet works. For most of the world’s users this is a good thing, but for some of us, it may slow things down.
SDN (Sometimes called the Cisco killer) is all about separating network control. In the Internet today, switches and routers that make up its backbone, each have embedded rules that determine how packets are routed. With SDN, each switch has a software defined set of rules that are built dynamically by talking to an SDN controller. If a low level network device encounters a new type of traffic, it asks its controller what it should do using a protocol like OpenFLow.
The controller sends down an enhancement to the local rules which look a lot like a current day set of traffic shaping queues. They allow the switch to prioritize the traffic (Pick an internal queue) and determine which port to send it out. The physical output port may effect the physical path that the packet will then take to traverse the Internet.
Each local device functions independently in much the same way that they do today until a new flow is encountered. By defining the routing action in software and decoupling control, service providers have more control over network flows. You might say that this sounds a lot like what MPLS was supposed to do, and you would be right.
SDN is very much like a soft and dynamic MPLS. MPLS promised traffic segregation that guaranteed Quality Of Service (QOS), but it cost more to implement and manage and sometimes added latency and decreased network throughput.
SDN promises high QOS, dynamic control over traffic flows and will cost the same or less. In most cases it will increase network throughput unless the traffic in question is traffic that the service provider has decided gets a lower priority.
I suspect that unencrypted torrents would be a natural target.