User‐perceived availability of priority shared protection systems

Purpose – The purpose of this paper is to derive the user‐perceived availability of M‐for‐N shared protection systems composed of multiple user groups, each with a protection‐switching priority. Design/methodology/approach – The paper assumes a shared protection system with M protection units and N working units. The memoryless state transition diagram viewed from the system administrator, combined with combinatorial analysis of state probabilities on protection switching, yields a generic formula of the availability viewed from an arbitrary end user. Findings – The numerical examples of availability reveal the effect of prioritized protection switching. It is observed that the total protection capacity is constant regardless of the ways of priority grouping. The shared protection system with multiple protection units enables more flexible availability allocation compared with the case of a single protection unit. Research limitations/implications – User‐perceived reliability is still an unexplored research area. Many variations of the system treated in this paper can be applied to various applications. Practical implications – The analysis provides useful information for the design and operation of, for example, telecommunication network devices. The analysis is applicable to general shared protection systems that are subject to service level agreement (SLA) involving user‐perceived reliability measures. Originality/value – This paper establishes the model of the priority shared protection systems for the first time and shows a practical computation method of prioritized user‐perceived availability.