The New (Pareto) Frontier of Cloud Routing: High Availability, Precise Control, or Configuration Stability - Choose Two

Clouds provide latency-sensitive services to clients at geographically distributed sites. They need precise control of client-site mappings for performance and, if a site fails, fast failover to other sites without cascading failures due to failover-induced overload or risky routing reconfiguration. However, clouds today route clients to sites by anycast or unicast with DNS-based redirection--methods that compromise either control or availability. In fact, even beyond these existing techniques, we find that all general-purpose approaches for directing clients to sites face inevitable tradeoffs among control, availability, and routing stability. We then present new general-purpose routing techniques and demonstrate via Internet-scale experiments that they provide much better tradeoffs among these three goals than existing techniques. One of our techniques achieves anycast's advantages with much better control, and another speeds up unicast's failover while preserving its advantages. Our techniques establish a new Pareto frontier for cloud routing.