SNF: Serverless Network Functions

Our work addresses how a cloud provider can offer Network Functions (NF) as a Service, or NFaaS, using the emerging serverless computing paradigm. Serverless computing has the right NFaaS building blocks - usage-based billing, event-driven programming model and elastic scaling. But we identify two core limitations of existing serverless platforms that undermine support for NFaaS - coupling of the billing and work assignment granularities, and state sharing via an external store. Our framework, SNF, overcomes these limitations via two ideas. SNF allocates work at the granularity of flowlets observed in network traffic, whereas billing and programming occur at a finer level. SNF embellishes serverless platforms with ephemeral local state that lasts for the flowlet duration and supports high performance state operations. We demonstrate that our SNF prototype matches utilization closely with demand and reduces tail packet processing latency substantially compared to alternatives.