The New (Pareto) Frontier of Cloud Routing: High Availability, Precise Control, or Stable — Choose Two#

Jiangchen Zhu; Ethan Katz-Bassett (Columbia University); Tom Koch (Google); Matt Calder (Meta); Italo Cunha (UFMG); Kevin Vermeulen (CNRS, École Polytechnique); Shuyue Yu; Ilgar Mammadov (Columbia University)

• Why: Best Paper, and directly on the anycast-vs-DNS-redirection problem every large service faces for client-to-site mapping. It proves a structural tradeoff rather than proposing yet another mapping system — that reframing is what makes it worth a practitioner's time.
• What: A demonstration that general-purpose client-to-site direction methods face inevitable tradeoffs among precise control, high availability, and routing stability, plus new routing techniques that establish a better Pareto frontier than anycast or DNS-based unicast redirection. One technique speeds unicast failover by up to 5 minutes while keeping unicast's control advantages; another achieves anycast's availability with far better control (from abstract only).
• How: Formal analysis of the three-way tradeoff, then new mapping/failover mechanisms validated via Internet-scale experiments — not simulation. Google and Meta authorship signals access to real production constraints (failover load on healthy sites, cascading-failure risk).
• Where applicable: Geographically distributed, latency-sensitive services mapping clients to sites at global scale. The techniques target the largest clouds' problems; the tradeoff framing, however, applies to anyone choosing between anycast and DNS-based redirection for multi-region service frontends.