Traffic flows are often processed by a chain of Service Functions (SFs) (known as Service Function Chaining (SFC)) to satisfy service requirements. The deployed path for a SFC is called Service Function Path (SFP). SFs can be virtualized and migrated to datacenters, thanks to the evolution of Software Defined Network (SDN) and Network Function Virtualization (NFV). In such a scenario, provisioning of paths (i.e., SFPs) between virtualized network functions is an important problem. SFP provisioning becomes more complex in a multi-domain network topology. ‘Topology aggregation’ helps to create a single-domain view of such a network by abstracting multi-domain networks. However, traditional ‘topology aggregation’ methods are unable to abstract SF resources properly, which is required for SFP provisioning. In this paper, we propose an SFC-Oriented Topology Aggregation (SOTA) method to enable abstraction for SFs in multi-domain optical networks. This study explores the node and the link aggregation degree to evaluate information compression during the ‘Topology aggregation’ process. Additionally, we also propose a new data structure named wheel matrix and related operations to store routing information in the aggregated topology. Based on SOTA, we propose two cross-domain SFP provisioning algorithms named Ordered Anchor Selection (OAS) and ${k}$ -paths OAS (K-OAS), and a benchmark named Global OAS (GOAS). Simulation results show that SOTA could aggregate large-scale multi-domain optical networks into a small network that contains only 6.9% of the nodes and 10.1% of the links. Both OAS and K-OAS can calculate SFPs efficiently and reduce blocking probability up to 52.10% compared to the benchmark.

中文翻译：

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多域光网络中具有拓扑聚合功能的服务功能路径供应

流量通常由服务功能链（SF）（称为服务功能链（SFC））处理，以满足服务需求。SFC的部署路径称为服务功能路径（SFP）。由于软件定义网络（SDN）和网络功能虚拟化（NFV）的发展，可以将SF虚拟化并迁移到数据中心。在这种情况下，在虚拟化网络功能之间提供路径（即SFP）是一个重要的问题。在多域网络拓扑中，SFP设置变得更加复杂。“拓扑聚合”通过抽象多域网络来帮助创建此类网络的单域视图。但是，传统的“拓扑聚合”方法无法正确抽象SF资源，这是SFP配置所必需的。在本文中，我们提出了一种面向SFC的拓扑聚合（SOTA）方法，以实现多域光网络中SF的抽象。这项研究探索了节点和链路聚合程度，以评估“拓扑聚合”过程中的信息压缩。此外，我们还提出了一种新的名为轮矩阵的数据结构以及相关的操作，以将路由信息存储在聚合拓扑中。基于SOTA，我们提出了两种跨域SFP配置算法，分别称为有序锚定选择（OAS）和 我们还提出了一种新的数据结构，命名为Wheel矩阵和相关操作，以将路由信息存储在聚合拓扑中。基于SOTA，我们提出了两种跨域SFP配置算法，分别称为有序锚定选择（OAS）和 我们还提出了一种新的数据结构，命名为Wheel矩阵和相关操作，以将路由信息存储在聚合拓扑中。基于SOTA，我们提出了两种跨域SFP配置算法，分别称为有序锚定选择（OAS）和 $ {k} $ -paths OAS（K-OAS），以及称为全球OAS（GOAS）的基准。仿真结果表明，SOTA可以将大规模的多域光网络聚合为一个仅包含6.9％的节点和10.1％的链路的小型网络。与基准相比，OAS和K-OAS均可有效地计算SFP，并将阻塞概率降低多达52.10％。