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ZooRoute: Enhancing Cloud-Scale Network Reliability via Candidate Path Provisioning and Overlay Proactive Rerouting#

NSDI '26 digest Program Core pick 4–6 May 2026

Abstract Paper Slides Recording

Xiaoqing Sun (Alibaba Cloud), Xing Li (Zhejiang University and Alibaba Cloud), Xionglie Wei, et al. (Alibaba Cloud), Yang Xu (Fudan), Shunmin Zhu (Alibaba Cloud), et al.

Play the recording: ZooRoute: Enhancing Cloud-Scale Network Reliability via Candidate Path Provisioning and Overlay Proactive Rerouting

  • Why: Fast, deterministic failure recovery offered by the cloud provider instead of pushing HA plumbing onto tenants — an explicit product decision worth understanding. The mechanism is a clever use of an oft-ignored header field.
  • What: A tenant-transparent, underlay-agnostic failure-recovery service, deployed 26 months in Alibaba Cloud: cumulative outage time reduced 93.19%, and 98.21% of failures masked from tenant awareness.
  • How: Reroutes traffic by varying the outer source port on VXLAN encapsulation — different source ports hash to different underlay paths. Tunnel endpoints proactively probe a set of healthy source-port candidates per destination IP, guaranteeing one-shot deterministic reroute onto a known-good path. Engineering challenges addressed: hypervisor probing overhead, Tofino-gateway memory limits, and stateful middlebox disruption.
  • Where applicable: Planet-scale cloud overlays (Alibaba production, Tofino gateways). The source-port-as-path-selector trick is broadly reusable in any ECMP-overlay network; the full proactive-probing service assumes provider control of both tunnel endpoints.