This paper presents our design and experience with a microkernel-inspired approach to host networking called Snap. Snap is a userspace networking system that supports Google's rapidly evolving needs with flexible modules that implement a range of network functions, including edge packet switching, virtualization for our cloud platform, traffic shaping policy enforcement, and a high-performance reliable messaging and RDMA-like service. Snap has been running in production for over three years, supporting the extensible communication needs of several large and critical systems.

Reconfigurable network hardware makes it easier to experiment with and prototype high-speed networking systems. However, these devices are still relatively hard to program; for example, requiring users to develop in Verilog or VHDL. Further, these devices are commonly designed to work with software on a host computer, requiring the co-development of these hardware and software components.