October 31, 2011

What's up in networks (1/3): openflow

I found time to go a bit deeper into several (not-that-fresh) topics. I hope this quick summary will be of interest for those who did not. First of this mini-series: OpenFlow

OpenFlow, or the Software-Defined Networks:
Thanks to OpenFlow, I now understand the "control plane vs. data plane" idea, which I thought were mysterious magic words allowing telco engineers to recognize themselves. In the OpenFlow world, there are some dumb switches that route packets according to a routing table, and there is a clever controller, which orchestrates these switches. Switch-Controller communication uses the OpenFlow protocol.

The first novelty is that the OpenFlow protocol has been designed at Stanford, therefore (i) it is cool, (ii) software engineers have heard about it, and (iii) it is endorsed by a buzz concept, namely software-defined networking. The second novelty, but a noteworthy one, is that the main network equipment vendors integrate OpenFlow API in their switches (at least Juniper and Cisco). So, it is becoming real: software developers will really be able to control a network remotely.

OpenFlow is both networks and software:
  • In the network area, there is only one truth: every new concept is something already done twenty years ago. Good news for OpenFlow: it looks like MPLS. Therefore OpenFlow is a networking concept. \qed
  • Computer scientists are driven by vaporous concepts like model abstraction, composition and semantic. Guess what? OpenFlow designers dangerously embrace them. Even worse, network scientists have started publishing in POPL and ICFP.
More seriously, OpenFlow meets a demand. More and more "independent" networks have specific needs that cannot been addressed by router vendors. For example the network in a data-center. Private enterprise networks and even next-generation home networks are also complex networks, which would work better if they could be managed according to the wishes of their owner. OpenFlow provides the friendly interface that allow anybody (should (s)he knows programming) to become the network operator for any such network. Needless to say, this perspective brings a lot of excitements and uncertainties (see for example here and here).


  1. If you have any issues in your open flow system make sure that switches are correctly connected and router is working alright.This step will troubleshoot any problem related to open flow problem.

  2. I think the open flow system facing trouble whenever the switches are not working or may b router is now working properly.If you face any problem in your open flow system must check your switches and routers.

  3. I think the main problem with OpenFlow is not what you both have mentioned here, but when the centralized controller crashes!