How Kube-OVN Enhances KubeVirt with Fixed IP, Multi‑Tenant, and SR‑IOV Support

Background

Enterprises increasingly run virtualized workloads on Kubernetes with KubeVirt. VM networking requires stable addressing and higher performance than typical container networks, which can become a bottleneck for cloud‑native virtualization.

Kube‑OVN enhancements for KubeVirt

Fixed IP for VMs

Kube‑OVN can allocate a specific IP that remains unchanged for the entire lifecycle of a VirtualMachine, including restarts, upgrades, and live migrations. The IP is set via an annotation on the VM spec.

apiVersion: kubevirt.io/v1alpha3
kind: VirtualMachine
metadata:
  name: testvm
spec:
  template:
    metadata:
      annotations:
        ovn.kubernetes.io/ip_address: 10.16.0.15

Random IP with lifetime stability

If administrators prefer automatic IP assignment but still need the address to stay constant, Kube‑OVN links the allocated IP to the VirtualMachine resource. Enable the feature by adding the controller flag:

--keep-vm-ip=true

Fixed IP during live migration

KubeVirt’s live migration uses the default network for state transfer, which can conflict with a fixed IP. Kube‑OVN solves this by attaching an auxiliary NIC via Multus and applying two annotations.

Attach Kube‑OVN as an auxiliary NIC to the VM.

Add the annotation

<attach>.<ns>.ovn.kubernetes.io/allow_live_migration: "true"

to enable live‑migration support.

Add the annotation

<attach>.<ns>.ovn.kubernetes.io/default_route: "true"

to correct the default route set by KubeVirt’s DHCP.

Multi‑tenant network support

Kube‑OVN introduces CRDs for VPC, Subnet, and NAT‑Gateway, providing Kubernetes‑level multi‑tenant isolation. By assigning VMs to specific VPCs and subnets, workloads are isolated per tenant. Additional tenant‑level services such as LoadBalancer, Elastic IP, NAT, and route tables are also available.

SR‑IOV and OVS‑DPDK acceleration

Kube‑OVN integrates OVS offload to pass SR‑IOV devices directly to KubeVirt VMs, delivering high‑performance networking while retaining OVN logical flow management. Experimental support for OVS‑DPDK enables user‑space acceleration for VM traffic, even on standard NICs.

References

https://github.com/kubeovn/kube-ovn/issues/1297

https://github.com/kubeovn/kube-ovn/pull/1307

https://github.com/kubeovn/kube-ovn/pull/1001

https://github.com/kubeovn/kube-ovn/blob/master/docs/static-ip.md

https://github.com/kubeovn/kube-ovn/blob/master/docs/vpc.md

https://github.com/kubeovn/kube-ovn/blob/master/docs/hw-offload-mellanox.md