What is Azure Service Mesh and how does it relate to Istio?

Azure Service Mesh capabilities are provided through Open Service Mesh (OSM) and the Istio-based service mesh add-on for AKS. A service mesh handles cross-cutting concerns for microservices: mTLS (mutual TLS for encrypted, authenticated inter-service communication), traffic management (canary deployments, circuit breaking, retries), observability (distributed tracing, metrics per service-to-service call). The AKS Istio add-on is a managed Istio installation — Microsoft handles upgrades and security patches. Key Istio concepts: Envoy sidecar proxies intercept all pod traffic. VirtualService defines routing rules. DestinationRule defines traffic policies. PeerAuthentication enforces mTLS. Service meshes add operational complexity — evaluate if the benefits justify the overhead for your architecture.