Scalable programmable inbound traffic engineering.

With the rise of video streaming and cloud services, enterprise and access networks receive much more traffic than they send, and must rely on the Internet to offer good end-to-end performance. These edge networks often connect to multiple ISPs for better performance and reliability, but have only limited ways to influence which of their ISPs carries the traffic for each service. In this paper, we present Sprite, a software-defined solution for flexible inbound traffic engineering (TE). Sprite offers direct, fine-grained control over inbound traffic, by announcing different public IP prefixes to each ISP, and performing source network address translation (SNAT) on outbound request traffic. Our design achieves scalability in both the data plane (by performing SNAT on edge switches close to the clients) and the control plane (by having local agents install the SNAT rules). The controller translates high-level TE objectives, based on client and server names, as well as performance metrics, to a dynamic network policy based on real-time traffic and performance measurements. We evaluate Sprite with live data from "in the wild" experiments on an EC2-based testbed, and demonstrate how Sprite dynamically adapts the network policy to achieve high-level TE objectives, such as balancing YouTube traffic among ISPs to improve video quality.