In order to support modern, responsive, real-time experiences across thousands of microservices, at Intuit we needed a solution for high-performance networking at scale. We began to accept that the limitations of our Hub and Spoke API Gateway model would be impossible to patch. With a significant move to Kubernetes within the company and with Service Mesh technologies on the near horizon, we began the journey to bring Service Mesh to our enterprise. We quickly discovered that deploying Istio for the enterprise comes with a host of challenges. Supporting multi-region deployments with non-flat networks and securely managing multitenant configuration across hundreds of Kubernetes clusters proved challenging. This talk details how Intuit solved these problems while deploying and managing Istio multi-cluster at scale in production.