Modeling and performance analysis of hybrid systems by queues with setup time

NFV (Network Functions Virtualization) is a technology to provide network services by applying virtualization. While the virtualization technology provides flexible architecture by itself, a specific environment where physical legacy equipment and virtualized machines coexist is also considered to meet a wide range of requirements from not only users but also service providers. Motivated by such hybrid systems, we propose queueing models with two types of service facilities: legacy servers and virtual machines. Key features to focus on are that while legacy servers are always on standby, virtual machines need setup time to be ready for service because they are shutdown to reduce the power consumption if no jobs are waiting. Keeping in mind delay-sensitive real-time services, we evaluate the performance of the queueing models, in particular, the delay and energy efficiency.