Distributed software defined network-based fog to fog collaboration scheme

Fog computing was created to supplement the cloud in bridging the communication delay gap by deploying fog nodes nearer to Internet of Things (IoT) devices. Depending on the geographical location, computational resource and rate of IoT requests, fog nodes can be idle or saturated. The latter requires special mechanism to enable collaboration with other nodes through service offloading to improve resource utilization. Software Defined Network (SDN) comes with improved bandwidth, latency and understanding of network topology, which recently attracted researchers attention and delivers promising results in service offloading. In this study, a Hierarchical Distributed Software Defined Network-based (DSDN) fog to fog collaboration model is proposed; the scheme considers computational resources such as available CPU and network resources such as communication hops of a prospective offloading node. Fog nodes having limited resources coupled with the projected high demand for fog services in the near future, the model also accounts for extreme cases in which all nearby nodes in a fog domain are saturated, employing a supervisor controller to scale the collaboration to other domains. The results of the simulations carried out on Mininet shows that the proposed multi-controller DSDN solution outperforms the traditional single controller SDN solution, it also further demonstrate that increase in the number of fog nodes does not affect service offloading performance significantly when multiple controllers are used.