Kube-OVN is a Kubernetes CNI plugin that uses OVN (Open Virtual Network) and Open vSwitch as its data plane. OVN originated in the OpenStack/Neutron world, and Kube-OVN wraps it to deliver Kubernetes pod networking with the kind of SDN features the traditional CNI plugins (Flannel, Calico) do not emphasise.
Each Kubernetes Namespace maps to an OVN logical switch by default, so you get subnet-per-namespace, native IPAM, and subnet-level QoS/ACLs out of the box. Beyond that it ships static IPs for pods, multiple subnets and IP pools, VPCs with overlapping CIDRs, virtual routers, load balancers, ECMP, BGP/VXLAN underlay modes, DPDK/Hardware offload for high throughput, and a SR-IOV/Offload path for bare metal. Multus multi-NIC, dual-stack IPv4/IPv6, and egress gateways are all supported. Observability pulls through OVN flow tracing, kubectl ko pktmon utilities, and Prometheus metrics on flow table depth, conntrack entries, and per-pod traffic.
Kube-OVN is heavy compared to Flannel or Calico, but that is the point — it is aimed at telco/NFV, edge, and multi-tenant workloads that need VPC-like isolation, overlapping IP spaces, or per-workload QoS that Calico’s BGP-first model does not cover cleanly.