Enabling Dual‑Stack Networking in KubeVirt with managedTap (Bridge Mode)

Background – As Kubernetes becomes the standard for modern application deployment, KubeVirt extends its capabilities by supporting virtual machines. Enabling IPv4 and IPv6 dual‑stack networking on VMs traditionally required source‑code modifications, which increased upgrade and maintenance costs.

KubeVirt 1.4 introduces managedTap , a new DomainAttachmentType that provides a TAP + Bridge based binding method, allowing dual‑stack support without source changes and simplifying configuration.

How managedTap works – managedTap automates the creation and configuration of the required network devices, offering a bridge binding without IPAM. Unlike the classic bridge mode where the VM relies on the virt‑launcher DHCP server, managedTap delegates DHCP management to Kube‑OVN.

Steps to enable dual‑stack with Kube‑OVN bridge forwarding

1. Enable DHCP and IPv6 RA on a Kube‑OVN subnet . Example YAML:

apiVersion: kubeovn.io/v1
kind: Subnet
metadata:
  name: dual-stack-subnet
spec:
  cidrBlock: "10.244.0.0/16,fd00:10:244::/64"
  enableDHCP: true
  enableIPv6RA: true

2. Register the managedTap network binding plugin with KubeVirt using a patch command:

kubectl patch kubevirts -n kubevirt kubevirt \
  --type=json -p='[{"op": "add", "path": "/spec/configuration/network", "value": {"binding": {"managedtap": {"domainAttachmentType": "managedTap"}}}}]'

3. Create a virtual machine that uses the managedTap interface . Example VM manifest snippet:

apiVersion: kubevirt.io/v1
kind: VirtualMachine
metadata:
  name: dual-stack-vm
  namespace: default
spec:
  running: false
  template:
    spec:
      domain:
        devices:
          interfaces:
          - name: default
            binding:
              name: managedtap
      networks:
      - name: default
        pod: {}

By following these steps, you can enable dual‑stack networking for VMs under bridge forwarding without altering KubeVirt source code, simplifying configuration and easing future upgrades.

References and further reading are provided at the end of the original article.