How to orchestrate a distributed OpenStack

We see two important trends in ICT nowadays: the backend of online applications and services are moving to the cloud, and for delay-sensitive ones the cloud is being extended with fogs. The reason for these phenomena is most importantly economic, but there are other benefits too: fast service creation, flexible reconfigurability, and portability. The management and orchestration of these services are currently separated to at least two layers: virtual infrastructure managers (VIMs) and network controllers operate their own domains, it should consist of compute or network resources, while handling services with cross-domain deployment is done by an upper-level orchestrator. In this paper we show the slight modification of OpenStack, the mainstream VIM today, which enables it to manage a distributed cloud-fog infrastructure. While our solution alleviates the need for running OpenStack controllers in the lightweight edge, it takes into account network aspects that are extremely important in a resource setup with remote fogs. We propose and analyze an online resource orchestration algorithm, we describe the OpenStack-based implementation aspects and we also show large-scale simulation results on the performance of our algorithm.