Istio vs OVN-Kubernetes

Istio is a free, open-source service mesh that adds security, connectivity, and monitoring for distributed applications with few or no service-code changes. It manages HTTP, gRPC, WebSocket, and TCP traffic, with automatic load balancing, routing rules, retries, failovers, and fault injection. Deployment options include sidecar mode and ambient mode, which uses a per-node Layer 4 proxy and can optionally add a per-namespace Envoy proxy for Layer 7 features. The control plane runs on Kubernetes, while the mesh can extend to other clusters, virtual machines, and endpoints outside Kubernetes. Security capabilities include workload identity, mutual TLS, authentication, authorization policies, and audit tools. Istio can generate traffic metrics, logs, and traces, including for ingress and egress. It can be installed with istioctl or Helm, and its integrations documentation covers tools such as Prometheus, Grafana, Jaeger, Kiali, and cert-manager. Istio 1.31 supports Kubernetes versions 1.32 through 1.36. Supported releases receive critical-issue patches and technical assistance from the community; development builds have no support.

OVN-Kubernetes is a free, open-source networking solution and CNI-conformant plugin for Kubernetes, built on OVN and Open vSwitch. It handles pod IP allocation and interfaces, GENEVE overlays, Kubernetes Services, EndpointSlices, network policies, and IPv4/IPv6 dual-stack clusters. OVN ACLs enforce NetworkPolicy, AdminNetworkPolicy, and EgressFirewall rules; EgressIP, EgressService, and EgressQoS govern outbound traffic. Pods can join multiple networks, and the project also supports multicast, traffic shaping, BGP route advertisements, and SmartNIC or DPU offload. For KubeVirt, it provides persistent IPs during live migration; Hybrid Overlay enables mixed Windows and Linux networking. Deployment documentation covers Kind, Helm, DPU acceleration, kubeadm, and source builds. Requirements depend on OVN, nft, Multus, CNI, and Kubernetes versions; the master branch lists Kubernetes 1.33 or newer. Secondary User Defined Networks currently lack north-south traffic and core Kubernetes Services support. AdminNetworkPolicy APIs remain alpha and may change before stable v1.