Most softwarized telco services are conveniently framed as service function chains (SFCs). Indeed, being structured as a combination of interconnected nodes, service chains may suffer from the single point of failure problem, meaning that an individual node malfunctioning could compromise the whole chain operation. To guarantee highly available (HA) levels, service providers are required to introduce redundancy strategies to achieve specific availability demands, where cost constraints have to be taken into account as well. Along these lines we propose HASFC, a framework designed to support, through a dedicated REST interface, the MANO infrastructure in deploying SFCs with an optimal availability/cost trade-off. Our framework is equipped with: an availability model builder aimed to construct probabilistic models of the SFC nodes in terms of failure/repair actions; and a chaining and selection module to compose the possible redundant SFCs, and extract the best candidates thereof. Beyond providing architectural details, we demonstrate the functionalities of HASFC through a use case that considers the IP Multimedia Subsystem, an SFC-like structure adopted to manage multimedia contents within 4G/5G networks.

中文翻译：

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HASFC：符合 MANO 的服务链可用性管理框架

大多数软件化的电信服务都可以方便地构建为服务功能链 (SFC)。事实上，作为互连节点的组合，服务链可能会遇到单点故障问题，这意味着单个节点故障可能会危及整个链的运行。为了保证高可用 (HA) 水平，服务提供商需要引入冗余策略来实现特定的可用性需求，同时还必须考虑成本限制。沿着这些思路，我们提出了 HASFC，这是一个框架，旨在通过专用的 REST 接口支持 MANO 基础设施以最佳的可用性/成本权衡部署 SFC。我们的框架配备了：可用性模型构建器，旨在根据故障/修复操作构建 SFC 节点的概率模型；以及链接和选择模块来组成可能的冗余SFC，并从中提取最佳候选。除了提供架构细节之外，我们还通过一个考虑 IP 多媒体子系统的用例来演示 HASFC 的功能，IP 多媒体子系统是一种类似 SFC 的结构，用于管理 4G/5G 网络中的多媒体内容。