The Cluster Network Operator

The Cluster Network Operator (CNO) deploys and manages the cluster network components on an OKD cluster, including the Container Network Interface (CNI) default network provider plug-in selected for the cluster during installation.

OKD uses the Cluster Network Operator for managing the SDN. This includes the network CIDR to use, the network mode, the network provider, and the IP address pools.

The Cluster Network Operator implements the network API from the API group. The Operator deploys the OpenShift SDN default Container Network Interface (CNI) network provider plug-in, or the default network provider plug-in that you selected during cluster installation, by using a daemon set.

Run the following oc get command as an administrative user to consult the SDN configuration, which is managed by the custom resource definition.

oc get cluster -oyaml

Cluster Network Operator configuration

The configuration for the cluster network is specified as part of the Cluster Network Operator (CNO) configuration and stored in a custom resource (CR) object that is named cluster. The CR specifies the fields for the Network API in the API group.

The CNO configuration inherits the following fields during cluster installation from the Network API in the API group and these fields cannot be changed:

  • clusterNetwork
    IP address pools from which pod IP addresses are allocated.
  • serviceNetwork
    IP address pool for services.
  • defaultNetwork.type
    Cluster network providers, such as OpenShift SDN or OVN-Kubernetes.