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3.5.7. 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 CR object that is named cluster. The CR specifies the parameters for the Network API in the operator.openshift.io API group.

You can specify the cluster network configuration for your OpenShift Container Platform cluster by setting the parameter values for the defaultNetwork parameter in the CNO CR. The following CR displays the default configuration for the CNO and explains both the parameters you can configure and the valid parameter values:

Cluster Network Operator CR

apiVersion: operator.openshift.io/v1
kind: Network
metadata:
  name: cluster
spec:
  clusterNetwork: 1
  - cidr: 10.128.0.0/14
    hostPrefix: 23
  serviceNetwork: 2
  - 172.30.0.0/16
  defaultNetwork: 3
    ...
  kubeProxyConfig: 4
    iptablesSyncPeriod: 30s 5
    proxyArguments:
      iptables-min-sync-period: 6
      - 0s

1 2
Specified in the install-config.yaml file.
3
Configures the default Container Network Interface (CNI) network provider for the cluster network.
4
The parameters for this object specify the kube-proxy configuration. If you do not specify the parameter values, the Cluster Network Operator applies the displayed default parameter values. If you are using the OVN-Kubernetes default CNI network provider, the kube-proxy configuration has no effect.
5
The refresh period for iptables rules. The default value is 30s. Valid suffixes include s, m, and h and are described in the Go time package documentation.
注記

Because of performance improvements introduced in OpenShift Container Platform 4.3 and greater, adjusting the iptablesSyncPeriod parameter is no longer necessary.

6
The minimum duration before refreshing iptables rules. This parameter ensures that the refresh does not happen too frequently. Valid suffixes include s, m, and h and are described in the Go time package.

3.5.7.1. Configuration parameters for the OpenShift SDN default CNI network provider

The following YAML object describes the configuration parameters for the OpenShift SDN default Container Network Interface (CNI) network provider. 

defaultNetwork:
  type: OpenShiftSDN 1
  openshiftSDNConfig: 2
    mode: NetworkPolicy 3
    mtu: 1450 4
    vxlanPort: 4789 5
1
Specified in the install-config.yaml file.
2
Specify only if you want to override part of the OpenShift SDN configuration.
3
Configures the network isolation mode for OpenShift SDN. The allowed values are Multitenant, Subnet, or NetworkPolicy. The default value is NetworkPolicy.
4
The maximum transmission unit (MTU) for the VXLAN overlay network. This is detected automatically based on the MTU of the primary network interface. You do not normally need to override the detected MTU.

If the auto-detected value is not what you expected it to be, confirm that the MTU on the primary network interface on your nodes is correct. You cannot use this option to change the MTU value of the primary network interface on the nodes.

If your cluster requires different MTU values for different nodes, you must set this value to 50 less than the lowest MTU value in your cluster. For example, if some nodes in your cluster have an MTU of 9001, and some have an MTU of 1500, you must set this value to 1450.

5
The port to use for all VXLAN packets. The default value is 4789. If you are running in a virtualized environment with existing nodes that are part of another VXLAN network, then you might be required to change this. For example, when running an OpenShift SDN overlay on top of VMware NSX-T, you must select an alternate port for VXLAN, since both SDNs use the same default VXLAN port number.

On Amazon Web Services (AWS), you can select an alternate port for the VXLAN between port 9000 and port 9999.