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Reliability-based controller placement algorithm in software defined networking

Software Defined Networking (SDN) change the routing architecture from 
 distribution to centralization. Then the centralized controller placement 
 becomes an important issue since network delay and synchronization will be 
 affected. In this paper, the problem of controller placement to optimize the 
 network average reliability is studied. We first consider the optimization 
 problem for controller placement under the assumption with the shortest path 
 between controller and switches, and a clustering based optimal controller 
 placement algorithm and sub-optimal algorithm base on greedy algorithm are 
 proposed, respectively. Then, we extend the controller placement problem to 
 more general case with multi-paths between controller and switches. In this 
 case, to reduce the computation complexity, a Reliability Factor is defined 
 to replace the network average reliability. After that, modified clustering 
 based and greedy based algorithms are proposed to make the optimal and 
 sub-optimal solution, respectively. Finally, simulation results demonstrate 
 the performance of the proposed algorithms better than regular placement 
 stratagem with the Internet2 OS3E and the Internet Topology Zoo.