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.

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.

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 cluster network provider.

• 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 fields. The host prefix must be 64 or greater. The IPv6 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.

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 cluster network provider.

• The cluster nodes have IPv6 addresses.

• You have enabled dual-stack networking.

Procedure

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

   $ oc edit networks.operator.openshift.io

2. Remove the IPv6 specific configuration that you have added to the cidr and hostPrefix fields in the previous procedure.