In the Service-Function-Chaining (SFC) enabled networks, various sophisticated policy-aware network functions, such as intrusion detection, access control and unified threat management, can be realized in either physical middleboxes or virtualized network function (VNF) appliances. In this paper, we study the service chaining towards the hybrid SFC clouds, where both physical appliances and VNF appliances provide services collaboratively. In such hybrid SFC networks, the challenge is how to efficiently steer the service chains for traffic demands while matching their individual policy chains concurrently such that a utility associated with the total admitted traffic rate and the induced overheads can be maximized. We find such problem has not been well solved so far. To this end, we devise a Markov Approximation (MA) based algorithm. The approximation property of the proposed algorithm is also proved. Extensive evaluation results show that the proposed MA algorithm can yield near-optimal solutions and outperform other benchmark algorithms significantly.

中文翻译：

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混合网络功能的服务链

在支持服务功能链 (SFC) 的网络中，可以在物理中间盒或虚拟化网络功能 (VNF) 设备中实现各种复杂的策略感知网络功能，例如入侵检测、访问控制和统一威胁管理。在本文中，我们研究了面向混合 SFC 云的服务链，其中物理设备和 VNF 设备协同提供服务。在这种混合 SFC 网络中，面临的挑战是如何有效地引导服务链满足流量需求，同时同时匹配其各个策略链，从而使与总允许流量率和诱导开销相关的效用最大化。我们发现这样的问题目前还没有得到很好的解决。为此，我们设计了一种基于马尔可夫近似 (MA) 的算法。还证明了所提出算法的逼近性。广泛的评估结果表明，所提出的 MA 算法可以产生接近最优的解决方案，并且明显优于其他基准算法。