Service provisioning mechanisms implemented across 5G infrastructures take broadly into use the network service chain concept. Typically, it is coupled with Network Function Virtualization (NFV) paradigm, and consists in defining a pre-determined path traversed by a set of softwarized network nodes to provide specific services. A well known chain-like framework is the IP Multimedia Subsystem (IMS), a key infrastructure of 5G networks, that we characterize both by a performance and an availability perspective. Precisely, supported by a designed from scratch testbed realized through Clearwater platform, we perform a stochastic assessment of a softwarized IMS (softIMS) architecture where two main stages stand out: i) a performance analysis, where, exploiting the queueing network decomposition method, we formalize an optimization problem of resource allocation by modeling each softIMS node as an M/G/c system; ii) an availability assessment, where, adopting the Stochastic Reward Net methodology, we are able to characterize the behavior of softIMS in terms of failure/repair events, and to derive a set of optimal configurations satisfying a given availability requirement (e.g. five nines) while minimizing deployment costs. Two routines dubbed OptCNT and OptSearchChain have been devised to govern the performance and availability analyses, respectively.

中文翻译：

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网络服务链的可执行性：软化IP多媒体子系统的随机建模和评估

跨5G基础架构实施的服务供应机制广泛使用了网络服务链概念。通常，它与网络功能虚拟化（NFV）范例耦合，并且在于定义由一组软化网络节点遍历的预定路径以提供特定服务。一个众所周知的链状框架是IP多媒体子系统（IMS），它是5G网络的关键基础架构，我们从性能和可用性的角度来描述它们的特征。精确地，在通过Clearwater平台实现的从头开始设计的测试平台的支持下，我们对软化IMS（softIMS）架构进行了随机评估，该评估的两个主要阶段是：i）性能分析，其中利用排队网络分解方法，通过将每个softIMS节点建模为M / G / c系统，形式化资源分配的优化问题；ii）可用性评估，其中，采用随机奖励网方法，我们可以根据故障/修复事件来表征softIMS的行为，并得出满足给定可用性要求（例如，五个九）的一组最佳配置同时最大程度地降低部署成本。设计了两个例程OptCNT和OptSearchChain，分别控制性能和可用性分析。并获得一组满足给定可用性要求（例如，五个九）的最佳配置，同时将部署成本降至最低。设计了两个例程OptCNT和OptSearchChain，分别控制性能和可用性分析。并获得一组满足给定可用性要求（例如，五个九）的最佳配置，同时将部署成本降至最低。设计了两个例程OptCNT和OptSearchChain，分别控制性能和可用性分析。