Reliable and Time-Efficient Virtualized Function Placement

Reliability and time-efficiency are two key elements to consider in network design. Commonly, each is measured per service—availability probability of a specific service, the latency of a specific service, and overall—system average reliability and average latency, considering the demand for every service. Intuitively, minimizing latency requires minimizing the number of network elements a service makes use of. In a nonredundant environment, this would also guarantee the maximal reliability of a service, as reliability degrades when relying on more elements. However, reliability is often guaranteed by allocating backup resources. We explain that such redundancy or the joint support for multiple services can impose a tradeoff between reliability and time-efficiency criteria. In this article, we study the conditions for the existence of such a tradeoff and design solutions that jointly take care of both design goals.