Riptide: Jump-Starting Back-Office Connections in Cloud Systems

Large-scale cloud networks are constantly driven by the need for improved performance in communication between datacenters. Indeed, such back-office communication makes up a large fraction of traffic in many cloud environments. This communication often occurs frequently, carrying control messages, coordination and load balancing information, and customer data. However, ensuring such inter-datacenter traffic is delivered efficiently requires optimizing connections over large physical distances, which is non-trivial. Worse still, many large cloud networks are subject to complex configuration and administrative restrictions, limiting the types of solutions that can be implemented. In this paper, we propose improving the efficiency of datacenter to datacenter communication by learning the congestion level of links in between. We then use this knowledge to inform new connections made between the relevant datacenters, allowing us to eliminate the overhead associated with traditional slow-start processes in new connections. We further present Riptide, a tool which implements this approach. We present the design and implementation details of Riptide, showing that it can be easily executed on modern Linux servers deployed in the real world. We further demonstrate that it successfully reduces total transfer times in a production global-scale content delivery network (CDN), providing up to a 30% decrease in tail latency. We further show that Riptide is simple to deploy and easy to maintain within a complex existing network.