Multi-access Edge Computing (MEC) is an essential technology for the fifth generation (5G) of mobile networks. MEC enables low-latency services by bringing computing resources close to the end-users. The integration of 5G and MEC technologies provides a favorable platform for a wide range of applications, including various mission-critical applications, such as smart grids, industrial internet, and telemedicine, which require high dependability and security. Ensuring both security and dependability is a complex and critical task, and not achieving the necessary goals can lead to severe consequences. Joint modeling can help to assess and achieve the necessary requirements. Under these motivations, we propose an extension of a two-level availability model for a 5G-MEC system. In comparison to the existing work, our extended model (i) includes the failure of the connectivity between the 5G-MEC elements and (ii) considers attacks against the 5G-MEC elements or their interconnection. We implement and run the model in M\"{o}bius. The results show that a three-element redundancy, especially of the management and core elements, is needed and still enough to reach around 4-nines availability even when connectivity and security are considered. Moreover, the evaluation shows that slow detection of attacks, slow recovery from attacks, and bad connectivity are the most significant factors that influence the overall system availability.

翻译：多接入边缘计算（MEC）是第五代（5G）移动网络的关键技术。MEC通过将计算资源部署在靠近终端用户的位置，实现了低延迟服务。5G与MEC技术的集成为各类应用提供了有利平台，包括智能电网、工业互联网和远程医疗等多种关键任务应用，这些应用对高可靠性与安全性有严格要求。同时确保安全性与可靠性是一项复杂且关键的任务，若未能达成必要目标可能导致严重后果。联合建模有助于评估并实现这些必要需求。基于上述动机，我们提出了一种针对5G-MEC系统的双层可用性模型的扩展。与现有工作相比，我们的扩展模型（i）包含了5G-MEC组件间连接失效的情况，且（ii）考虑了针对5G-MEC组件或其互连关系的攻击行为。我们在Möbius中实现并运行了该模型。结果表明，即使考虑连接性与安全性因素，采用三组件冗余（尤其是管理与核心组件）仍是必要且足以实现约4个9的可用性。此外，评估显示攻击检测缓慢、攻击恢复迟缓以及连接质量差是影响系统整体可用性的最主要因素。