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Configuring hybrid networking

In OKD, you can configure OVN-Kubernetes hybrid networking so Linux and Windows nodes run Linux and Windows workloads in the same cluster.

Configuring hybrid networking with OVN-Kubernetes

To configure hybrid networking with OVN-Kubernetes, you can set hybridOverlayConfig during installation or patch the Cluster Network Operator (CNO) after installation.

This configuration is necessary to run both Linux and Windows nodes in the same cluster.
Prerequisites

  • Install the OpenShift CLI (oc).

  • Log in to the cluster as a user with cluster-admin privileges.

  • Ensure that the cluster uses the OVN-Kubernetes network plugin.

Procedure

  1. To configure the OVN-Kubernetes hybrid network overlay, enter the following command:

    $ oc patch networks.operator.openshift.io cluster --type=merge \
  -p '{
    "spec":{
      "defaultNetwork":{
        "ovnKubernetesConfig":{
          "hybridOverlayConfig":{
            "hybridClusterNetwork":[
              {
                "cidr": "<cidr>",
                "hostPrefix": <prefix>
              }
            ],
            "hybridOverlayVXLANPort": <overlay_port>
          }
        }
      }
    }
  }'

    where:

    <cidr>

    Specifies the CIDR configuration used for nodes on the additional overlay network. This CIDR must not overlap with the cluster network CIDR.

    <prefix>

    Specifies the subnet prefix length to assign to each individual node. For example, if hostPrefix is set to 23, then each node is assigned a /23 subnet out of the given cidr, which allows for 510 (2^(32 - 23) - 2) pod IP addresses. If you are required to provide access to nodes from an external network, configure load balancers and routers to manage the traffic.

    <overlay_port>

    Specifies a custom VXLAN port for the additional overlay network. This is required for running Windows nodes in a cluster installed on vSphere, and must not be configured for any other cloud provider. The custom port can be any open port excluding the default 6081 port. For more information on this requirement, see Pod-to-pod connectivity between hosts is broken in the Microsoft documentation.

    Windows Server Long-Term Servicing Channel (LTSC): Windows Server 2019 is not supported on clusters with a custom hybridOverlayVXLANPort value because this Windows server version does not support selecting a custom VXLAN port.
    Example output
    network.operator.openshift.io/cluster patched

  2. To confirm that the configuration is active, enter the following command. It can take several minutes for the update to apply.

    $ oc get network.operator.openshift.io -o jsonpath="{.items[0].spec.defaultNetwork.ovnKubernetesConfig}"

Additional resources