Oreo: Transparent Optimization to Enable Flexible Policy Enforcement in Softward Defined Networks

Commercial networks today have diverse security policies, defined by factors such as the type of traffic they carry, nature of applications they support, access control objectives, organizational principles etc. Ideally, the wide diversity in SDN controller frameworks should prove helpful in correctly and efficiently enforcing these policies. However, this has not been the case so far. By requiring the administrators to implement both security as well as performance objectives in the SDN controller, these frameworks have made the task of security policy enforcement in SDNs a challenging one. We observe that by separating security policy enforcement from performance optimization, we can facilitate the use of SDN for flexible policy management. To this end, we propose Oreo, a transparent performance enhancement layer for SDNs. Oreo allows SDN controllers to focus entirely on a correct security policy enforcement, and transparently optimizes the dataplane thus defined, reducing path stretch, switch memory consumption etc. Optimizations are performed while guaranteeing that end-to-end reachability characteristics are preserved - meaning that the security policies defined by the controller are not violated. Oreo performs these optimizations by first constructing a network-wide model describing the behavior of all traffic, and then optimizing the paths observed in the model by solving a multi-objective optimization problem. Initial experiments suggest that the techniques used by Oreo is effective, fast, and can scale to commercial-sized networks.