OpenFlow provides ability to control traffic flow in a very granular way in a centralized way. Instead of managing traffic on individual routers, I would have a services console that would like me manage them as a whole.
In a classical router or switch, the fast packet forwarding (data path) and the high level routing decisions (control path) occur on the same device. An OpenFlow Switch separates these two functions. The data path portion still resides on the switch, while high-level routing decisions are moved to a separate controller, typically a standard server. The OpenFlow Switch and Controller communicate via the OpenFlow protocol, which defines messages, such as packet-received, send-packet-out, modify-forwarding-table, and get-stats.
I think the benefits here are obvious and the implications are enormous when managing a large network. Another quote:
OpenFlow is an open standard that enables researchers to run experimental protocols in the campus networks we use every day. OpenFlow is added as a feature to commercial Ethernet switches, routers and wireless access points – and provides a standardized hook to allow researchers to run experiments, without requiring vendors to expose the internal workings of their network devices. OpenFlow is currently being implemented by major vendors, with OpenFlow-enabled switches now commercially available.
What's particularly interesting to me here is the ability to "run experimental protocols". I wouldn't have to wait for MikroTik to implement a particular routing protocol. I can implement it in OpenFlow.
So, to summarize, how would I use it in ways that aren't already do-able?
- Direct, centralized control over my entire routing infrastructure
- Implement specialized routing protocols that will allow me to optimize my network based on it's unique properties. For instance, OSPF is woefully inadequate to handle a wireless point-to-point infrastructure. The amount of bandwidth available on a link changes from moment to moment. This is just one example. There are newer routing protocols out there that are much better at this.