1. Documentation
×

Converting to IPv4/IPv6 dual-stack networking

As a cluster administrator, you can convert your IPv4 single-stack cluster to a dual-network cluster network that supports IPv4 and IPv6 address families. After converting to dual-stack, all newly created pods are dual-stack enabled.

  • While using dual-stack networking, you cannot use IPv4-mapped IPv6 addresses, such as ::FFFF:198.51.100.1, where IPv6 is required.

  • A dual-stack network is supported on clusters provisioned on bare metal, IBM Power®, IBM Z® infrastructure, single-node OpenShift, and VMware vSphere.

Converting to a dual-stack cluster network

As a cluster administrator, you can convert your single-stack cluster network to a dual-stack cluster network.

After converting to dual-stack networking only newly created pods are assigned IPv6 addresses. Any pods created before the conversion must be recreated to receive an IPv6 address.
Prerequisites

  • You installed the OpenShift CLI (oc).

  • You are logged in to the cluster with a user with cluster-admin privileges.

  • Your cluster uses the OVN-Kubernetes network plugin.

  • The cluster nodes have IPv6 addresses.

  • You have configured an IPv6-enabled router based on your infrastructure.

Procedure

  1. To specify IPv6 address blocks for the cluster and service networks, create a file containing the following YAML:

    - op: add
  path: /spec/clusterNetwork/-
  value: (1)
    cidr: fd01::/48
    hostPrefix: 64
- op: add
  path: /spec/serviceNetwork/-
  value: fd02::/112 (2)
    1 Specify an object with the cidr and hostPrefix parameters. The host prefix must be 64 or greater. The IPv6 Classless Inter-Domain Routing (CIDR) prefix must be large enough to accommodate the specified host prefix.
    2 Specify an IPv6 CIDR with a prefix of 112. Kubernetes uses only the lowest 16 bits. For a prefix of 112, IP addresses are assigned from 112 to 128 bits.

  2. To patch the cluster network configuration, enter the following command:

    $ oc patch network.config.openshift.io cluster \
  --type='json' --patch-file <file>.yaml

    where:

    file

    Specifies the name of the file you created in the previous step.

    Example output

    network.config.openshift.io/cluster patched
Verification

Complete the following step to verify that the cluster network recognizes the IPv6 address blocks that you specified in the previous procedure.

  1. Display the network configuration:

    $ oc describe network
    Example output

    Status:
  Cluster Network:
    Cidr:               10.128.0.0/14
    Host Prefix:        23
    Cidr:               fd01::/48
    Host Prefix:        64
  Cluster Network MTU:  1400
  Network Type:         OVNKubernetes
  Service Network:
    172.30.0.0/16
    fd02::/112

Converting to a single-stack cluster network

As a cluster administrator, you can convert your dual-stack cluster network to a single-stack cluster network.

If you originally converted your IPv4 single-stack cluster network to a dual-stack cluster, you can convert only back to the IPv4 single-stack cluster and not an IPv6 single-stack cluster network. The same restriction applies for converting back to an IPv6 single-stack cluster network.
Prerequisites

  • You installed the OpenShift CLI (oc).

  • You are logged in to the cluster with a user with cluster-admin privileges.

  • Your cluster uses the OVN-Kubernetes network plugin.

  • The cluster nodes have IPv6 addresses.

  • You have enabled dual-stack networking.

Procedure

  1. Edit the networks.config.openshift.io custom resource (CR) by running the following command:

    $ oc edit networks.config.openshift.io

  2. Remove the IPv4 or IPv6 configuration that you added to the cidr and the hostPrefix parameters from completing the "Converting to a dual-stack cluster network " procedure steps.