= Multiple Controllers (And making them cooperate). =
This page documents the process of designing a multi-controller !OpenFlow architecture where the controllers actively collaborate to emulate a network stack for experiments.  

== Quick Links. ==
[#i Overview.] [[BR]]

== Overview. == #i
The basic architecture for an !OpenFlow network is a client - server (switch - controller) model involving a single controller and one or more switches. Networks can host multiple controllers. !FlowVisor virtualizes a single network into slices so that it can be shared amongst various controllers, and the newest !OpenFlow standard (v1.3.0) defines ''equal'', ''master'' and ''slave'' controllers to coexist as part of a redundancy scheme in what would be a single slice. A multi-controller scheme that isn't really explored yet is one where each controller has a different function, and cooperate. 

Cooperation is a fairly complex task, for several reasons:

 * There must be a communication scheme so that the controllers can cooperate
 * A single protocol suite can be divided amongst controllers in various ways
 * The information being communicated between controllers changes with protocol suite and division of tasks 

Developing a general solution to this problem is difficult, so focus will be narrowed down to a more specific task of producing a cooperative multi-controller framework for running a topology configuration service split into a global and local component, and an experimental routing protocol with ID resolution.