Choosing TCP Variants for Cloud Tenants – A Measurement based Approach

Cloud computing has become the de-facto paradigm for fulfilling the computing needs of a myriad of applications like streaming, e-commerce, data analytics, etc. While a significant amount of work exists on how cloud providers can improve the networking performance of their cloud platforms, very little has been done to explore how a cloud tenant can achieve the best performance for their applications. In this paper, we study how the choice of the TCP variant impacts the performance achieved by tenant applications. We present a generic measurementbased approach to identify the best TCP variant for any given application in a given cloud environment. Our approach is comprised of first measuring several performance metrics including throughput, latency, and loss in the given cloud platform for several TCP variants, and then identifying the best TCP variant based on three things: observations from the measurements, nature of the traffic of the given application, and application requirements such as high throughput or low latency. We study the effectiveness of our approach by implementing it in two large public clouds, Amazon’s AWS and Google’s GCP, and present our observations from several case studies using three common cloud applications, namely streaming, distributed input-output, and sort, and four common TCP variants, namely Cubic, New Reno, BBR, and DCTCP. From our observations, we found that just by changing the TCP variant that an application uses, the average throughput can be increased by up to 13.7% and the round trip time can be decreased by up to 5 times.