The paper focuses on dynamic resource provisioning in an all optical wide area Software Defined Network supporting energy-aware interplay between fog and cloud. The main contribution of this paper is a latencyAware policy for handling fog related traffic. The policy is combined with anycast strategies in order to form a complete approach able to handle fog and cloud traffic simultaneously. The proposed approach was compared with reference solutions with respect to latency of fog related requests, CO₂ emission and impact on network performance. It is shown that both latency and carbon footprint may be reduced without significant deterioration of network performance.

Advantages of Software Defined Networking are unquestionable and are widely described in numerous scientific papers, business white papers and press articles. However, to achieve full maturity, crucial impediments to this concept and its shortcomings must be overcame. One of the most important issues regards significant setup latency of a new flow. To address this issue we propose PARD: a hybrid proactive and reactive method to manage flow table entries. Additional advantages of the proposed solution are, among the others, its ability to preserve all capabilities of Software Defined Networking, utilization of multiple flow tables, a possibility to employ fine-grained traffic engineering and, finally, compatibility with existing protocol and hardware design. It is shown that the proposed solution is able to significantly reduce latency of first packets of a new flow, which directly impacts packet loss and perceived throughput. Thus, our solution is expected to enable a wide deployment of Software Defined Networking concept without any need for protocol changes or, what is extremely important, hardware modifications.