A Service Function Chain (SFC) is an ordered sequence of network functions (NFs). Though cost-effective, software-based NFs could introduce a significant performance penalty. In this paper, we present P4SFC, a high-performance and flexible SFC system that leverages the capability of emerging programmable switches. We seek to accelerate packet processing in SFC by offloading proper NFs to P4-capable switches. First, considering the current limitations of P4, we analyze the offloadability of NFs at different granularities in detail, and enable P4SFC to generate offloading strategies for both partially and fully offloadable SFCs. Second, to deploy new SFCs at runtime, we design a dynamic P4 data plane, of which the execution logic can be reconfigured at runtime without interrupting the existed execution logic. Third, to efficiently utilize the limited memory in programmable switches, we propose a state allocator to dynamically offload those NF states that bring the highest performance profits according to the recent flow distribution. We demonstrate the feasibility and practicality of P4SFC with our implementation on a commodity Tofino-based programmable switch. Experimental results show that P4SFC achieves significant performance improvement for real SFC implementations.

中文翻译：

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将服务功能链灵活卸载到可编程交换机

服务功能链 (SFC) 是网络功能 (NF) 的有序序列。尽管具有成本效益，但基于软件的 NF 可能会带来显着的性能损失。在本文中，我们介绍了 P4SFC，这是一种高性能且灵活的 SFC 系统，它利用了新兴可编程开关的功能。我们寻求通过将适当的 NF 卸载到支持 P4 的交换机来加速 SFC 中的数据包处理。首先，考虑到 P4 当前的局限性，我们详细分析了不同粒度的 NF 的卸载能力，并使 P4SFC 能够为部分和完全可卸载的 SFC 生成卸载策略。其次，为了在运行时部署新的 SFC，我们设计了一个动态 P4 数据平面，其执行逻辑可以在运行时重新配置，而不会中断现有的执行逻辑。第三，为了有效地利用可编程开关中的有限内存，我们提出了一种状态分配器，可以根据最近的流量分布动态卸载那些带来最高性能利润的 NF 状态。我们通过在商品化的基于 Tofino 的可编程开关上的实施展示了 P4SFC 的可行性和实用性。实验结果表明，P4SFC 实现了实际 SFC 实现的显着性能改进。