We are aware of network congestion impacting select routes between North America and India. The issue is most pronounced for traffic transiting through Chennai data centers and is associated with ongoing subsea capacity constraints resulting from multiple cable cuts reported by upstream providers. During peak periods, customers may experience intermittent increases in latency, packet loss, or connection timeouts. Upstream providers have communicated an estimated timeframe for capacity restoration in January (ETA), subject to change.

Scope 
- Geography: Routes between the United States and India, with heightened impact to Chennai ingress/egress. 
- Services: Network performance on affected routes; other regions remain nominal. 
- Timeframe: Ongoing; congestion is variable and aligns with regional peak utilization windows.

Traffic Control Limitations 
- Forward path (US to Chennai) routing decisions are determined by upstream ISPs and carriers and are not under Zscaler's direct control. 
- Zscaler has reviewed and implemented changes on the return (Chennai to US) path to prefer healthier segments where feasible, reducing exposure to known congested corridors.

Current Status 
- Zscaler is actively coordinating with multiple upstream carriers and partners who have confirmed subsea cable damage and temporary capacity constraints. 
- Partners are performing traffic engineering and load redistribution within available bandwidth. Due to constrained backhaul, congestion can reoccur during peak periods until repairs/augments are completed. 
- Zscaler has adjusted routing preferences and peering policies where feasible to alleviate hot paths and reduce packet loss on impacted segments—particularly on the return path from Chennai to the United States.
- Zscaler continues to monitor latency, loss, and path stability across affected corridors and will apply additional optimizations as conditions evolve.

Estimated Time to Resolution (ETA) 
- Upstream providers currently estimate relief in January, contingent on subsea repair activities and capacity augments. This timeframe is subject to change based on marine conditions and repair windows. 

Monitoring and Updates 
- Zscaler is continuously monitoring performance metrics and upstream advisories. 
- Zscaler will provide updates on material changes to scope, impact, or timelines, or as new information becomes available from our partners. 

Contact 
- If you are experiencing ongoing degradation after applying the recommended workarounds, please contact Support with affected source/destination subnets, timestamps (UTC), traceroutes, and packet captures where available to assist with targeted path analysis. 

Next Steps 
- Maintain enhanced monitoring of North America–India paths, with emphasis on Chennai routes. 
- Continue coordination with upstream providers for restoration milestones and capacity management. 
- Evaluate and implement further routing and peering optimizations where viable without introducing risk.