Chapter 7. Cluster Network Operator in OpenShift Container Platform
You can use the Cluster Network Operator (CNO) to deploy and manage cluster network components on an OpenShift Container Platform cluster, including the Container Network Interface (CNI) network plugin selected for the cluster during installation.
7.1. Cluster Network Operator
The Cluster Network Operator implements the network
API from the operator.openshift.io
API group. The Operator deploys the OVN-Kubernetes network plugin, or the network provider plugin that you selected during cluster installation, by using a daemon set.
Procedure
The Cluster Network Operator is deployed during installation as a Kubernetes Deployment
.
Run the following command to view the Deployment status:
$ oc get -n openshift-network-operator deployment/network-operator
Example output
NAME READY UP-TO-DATE AVAILABLE AGE network-operator 1/1 1 1 56m
Run the following command to view the state of the Cluster Network Operator:
$ oc get clusteroperator/network
Example output
NAME VERSION AVAILABLE PROGRESSING DEGRADED SINCE network 4.5.4 True False False 50m
The following fields provide information about the status of the operator:
AVAILABLE
,PROGRESSING
, andDEGRADED
. TheAVAILABLE
field isTrue
when the Cluster Network Operator reports an available status condition.
7.2. Viewing the cluster network configuration
Every new OpenShift Container Platform installation has a network.config
object named cluster
.
Procedure
Use the
oc describe
command to view the cluster network configuration:$ oc describe network.config/cluster
Example output
Name: cluster Namespace: Labels: <none> Annotations: <none> API Version: config.openshift.io/v1 Kind: Network Metadata: Self Link: /apis/config.openshift.io/v1/networks/cluster Spec: 1 Cluster Network: Cidr: 10.128.0.0/14 Host Prefix: 23 Network Type: OpenShiftSDN Service Network: 172.30.0.0/16 Status: 2 Cluster Network: Cidr: 10.128.0.0/14 Host Prefix: 23 Cluster Network MTU: 8951 Network Type: OpenShiftSDN Service Network: 172.30.0.0/16 Events: <none>
7.3. Viewing Cluster Network Operator status
You can inspect the status and view the details of the Cluster Network Operator using the oc describe
command.
Procedure
Run the following command to view the status of the Cluster Network Operator:
$ oc describe clusteroperators/network
7.4. Enabling IP forwarding globally
From OpenShift Container Platform 4.14 onward, global IP address forwarding is disabled on OVN-Kubernetes based cluster deployments to prevent undesirable effects for cluster administrators with nodes acting as routers. However, in some cases where an administrator expects traffic to be forwarded a new configuration parameter ipForwarding
is available to allow forwarding of all IP traffic.
To re-enable IP forwarding for all traffic on OVN-Kubernetes managed interfaces set the gatewayConfig.ipForwarding
specification in the Cluster Network Operator to Global
following this procedure:
Procedure
Backup the existing network configuration by running the following command:
$ oc get network.operator cluster -o yaml > network-config-backup.yaml
Run the following command to modify the existing network configuration:
$ oc edit network.operator cluster
Add or update the following block under
spec
as illustrated in the following example:spec: clusterNetwork: - cidr: 10.128.0.0/14 hostPrefix: 23 serviceNetwork: - 172.30.0.0/16 networkType: OVNKubernetes clusterNetworkMTU: 8900 defaultNetwork: ovnKubernetesConfig: gatewayConfig: ipForwarding: Global
- Save and close the file.
After applying the changes, the OpenShift Cluster Network Operator (CNO) applies the update across the cluster. You can monitor the progress by using the following command:
$ oc get clusteroperators network
The status should eventually report as
Available
,Progressing=False
, andDegraded=False
.Alternatively, you can enable IP forwarding globally by running the following command:
$ oc patch network.operator cluster -p '{"spec":{"defaultNetwork":{"ovnKubernetesConfig":{"gatewayConfig":{"ipForwarding": "Global"}}}}}
NoteThe other valid option for this parameter is
Restricted
in case you want to revert this change.Restricted
is the default and with that setting global IP address forwarding is disabled.
7.5. Viewing Cluster Network Operator logs
You can view Cluster Network Operator logs by using the oc logs
command.
Procedure
Run the following command to view the logs of the Cluster Network Operator:
$ oc logs --namespace=openshift-network-operator deployment/network-operator
7.6. 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 operator.openshift.io
API group.
The CNO configuration inherits the following fields during cluster installation from the Network
API in the Network.config.openshift.io
API group:
clusterNetwork
- IP address pools from which pod IP addresses are allocated.
serviceNetwork
- IP address pool for services.
defaultNetwork.type
-
Cluster network plugin.
OVNKubernetes
is the only supported plugin during installation.
After cluster installation, you can only modify the clusterNetwork
IP address range. The default network type can only be changed from OpenShift SDN to OVN-Kubernetes through migration.
You can specify the cluster network plugin configuration for your cluster by setting the fields for the defaultNetwork
object in the CNO object named cluster
.
7.6.1. Cluster Network Operator configuration object
The fields for the Cluster Network Operator (CNO) are described in the following table:
Field | Type | Description |
---|---|---|
|
|
The name of the CNO object. This name is always |
|
| A list specifying the blocks of IP addresses from which pod IP addresses are allocated and the subnet prefix length assigned to each individual node in the cluster. For example: spec: clusterNetwork: - cidr: 10.128.0.0/19 hostPrefix: 23 - cidr: 10.128.32.0/19 hostPrefix: 23 |
|
| A block of IP addresses for services. The OpenShift SDN and OVN-Kubernetes network plugins support only a single IP address block for the service network. For example: spec: serviceNetwork: - 172.30.0.0/14
This value is ready-only and inherited from the |
|
| Configures the network plugin for the cluster network. |
|
| The fields for this object specify the kube-proxy configuration. If you are using the OVN-Kubernetes cluster network plugin, the kube-proxy configuration has no effect. |
defaultNetwork object configuration
The values for the defaultNetwork
object are defined in the following table:
Field | Type | Description |
---|---|---|
|
|
Note OpenShift Container Platform uses the OVN-Kubernetes network plugin by default. OpenShift SDN is no longer available as an installation choice for new clusters. |
|
| This object is only valid for the OVN-Kubernetes network plugin. |
Configuration for the OpenShift SDN network plugin
The following table describes the configuration fields for the OpenShift SDN network plugin:
Field | Type | Description |
---|---|---|
|
| The network isolation mode for OpenShift SDN. |
|
| The maximum transmission unit (MTU) for the VXLAN overlay network. This value is normally configured automatically. |
|
|
The port to use for all VXLAN packets. The default value is |
Example OpenShift SDN configuration
defaultNetwork: type: OpenShiftSDN openshiftSDNConfig: mode: NetworkPolicy mtu: 1450 vxlanPort: 4789
Configuration for the OVN-Kubernetes network plugin
The following table describes the configuration fields for the OVN-Kubernetes network plugin:
Field | Type | Description |
---|---|---|
|
| The maximum transmission unit (MTU) for the Geneve (Generic Network Virtualization Encapsulation) overlay network. This value is normally configured automatically. |
|
| The UDP port for the Geneve overlay network. |
|
| An object describing the IPsec mode for the cluster. |
|
| Specify a configuration object for customizing network policy audit logging. If unset, the defaults audit log settings are used. |
|
| Optional: Specify a configuration object for customizing how egress traffic is sent to the node gateway. Note While migrating egress traffic, you can expect some disruption to workloads and service traffic until the Cluster Network Operator (CNO) successfully rolls out the changes. |
|
If your existing network infrastructure overlaps with the This field cannot be changed after installation. |
The default value is |
|
If your existing network infrastructure overlaps with the This field cannot be changed after installation. |
The default value is |
Field | Type | Description |
---|---|---|
| integer |
The maximum number of messages to generate every second per node. The default value is |
| integer |
The maximum size for the audit log in bytes. The default value is |
| integer | The maximum number of log files that are retained. |
| string | One of the following additional audit log targets:
|
| string |
The syslog facility, such as |
Field | Type | Description |
---|---|---|
|
|
Set this field to
This field has an interaction with the Open vSwitch hardware offloading feature. If you set this field to |
|
|
You can control IP forwarding for all traffic on OVN-Kubernetes managed interfaces by using the |
Field | Type | Description |
---|---|---|
|
| Specifies the behavior of the IPsec implementation. Must be one of the following values:
|
You can only change the configuration for your cluster network plugin during cluster installation, except for the gatewayConfig
field that can be changed at runtime as a postinstallation activity.
Example OVN-Kubernetes configuration with IPSec enabled
defaultNetwork: type: OVNKubernetes ovnKubernetesConfig: mtu: 1400 genevePort: 6081 ipsecConfig: mode: Full
Using OVNKubernetes can lead to a stack exhaustion problem on IBM Power®.
kubeProxyConfig object configuration (OpenShiftSDN container network interface only)
The values for the kubeProxyConfig
object are defined in the following table:
Field | Type | Description |
---|---|---|
|
|
The refresh period for Note
Because of performance improvements introduced in OpenShift Container Platform 4.3 and greater, adjusting the |
|
|
The minimum duration before refreshing kubeProxyConfig: proxyArguments: iptables-min-sync-period: - 0s |
7.6.2. Cluster Network Operator example configuration
A complete CNO configuration is specified in the following example:
Example Cluster Network Operator object
apiVersion: operator.openshift.io/v1 kind: Network metadata: name: cluster spec: clusterNetwork: - cidr: 10.128.0.0/14 hostPrefix: 23 serviceNetwork: - 172.30.0.0/16 networkType: OVNKubernetes clusterNetworkMTU: 8900