Scalable On-Switch Rate Limiters for the Cloud

While most clouds use on-server rate limiters for bandwidth allocation, we propose to implement them on switches. On-switch rate limiters can simplify network management and promote the performance of control-plane rate limiting applications. We leverage the recent progress of programmable switches to implement on-switch rate limiters, named SwRL. In the design of SwRL, we make design choices according to the programmable hardware characteristics, we deeply optimize the memory usage of the algorithm so as to fit a cloud-scale (one million) rate limiters in a single switch, and we complement the missing computation primitives of the hardware using a pre-computed approximate table. We further developed three control-plane applications and integrate them with SwRL, showing the control-plane interoperability of SwRL. We prototype and evaluate SwRL in both testbed and production environments, demonstrating its good properties of precision rate control, scalability, interoperability, and manageability (execution environmental isolation).