I am working with Open Daylight Hydrogen controller and I want to know which routing protocol does it use by default to set the path for a flow. Is it possible to know those paths? What about other controllers as well like POX, Floodlight, etc?

  • Did any answer help you? if so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you could provide and accept your own answer.
    – Ron Maupin
    Commented Aug 12, 2017 at 3:24

2 Answers 2


No routing protocol is used.

The purpose of routing protocols is to tell other routers which paths are available, so the other routers can make a good forwarding decision. In SDN, the controller has a complete view of the network -- it already knows all the paths. The controller calculates the best path for a particular kind of data, and then uses a protocol like OpenFlow to tell the network devices how to forward data.

  • I want to know how controller calculates the best path for a particular kind of data. Is it DFS, BFS, ....? Where can we get this information?
    – user8109
    Commented Jul 22, 2015 at 5:47
  • Recently I came to know that we can implement any routing protocol on SDN controller. networkengineering.stackexchange.com/questions/20053/…
    – user8109
    Commented Jul 22, 2015 at 5:57
  • You can run a routing protocol to communicate with routers outside the domain, for example, to your ISP. But withing the SDN domain, there is no need for one.
    – Ron Trunk
    Commented Jul 22, 2015 at 12:30
  • @AbderrahmaneBOUHAFARA You misunderstand the idea of "protocol-less" The controller doesn't run a routing protocol, but it uses Openflow to communicate with its switches. That's how it learns addresses.
    – Ron Trunk
    Commented May 29, 2018 at 18:44

An SDN controller will utilize the openflow protocol to communicate with networking devices, whether they are physical or virtual. Openflow is not a routing protocol.

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