How to modify MTU in OpenShift 4 installation

Solution Verified - Updated

Environment

  • Red Hat OpenShift Container Platform (RHOCP)
    • 4

Issue

  • Is it possible to change MTU configuration during the OpenShift 4 installation?
  • It is unsupported to change MTU after installation?

Resolution

It is possible to configure the MTU size at installation time modifying the manifest created with the openshift-install create manifests command. There is more info about the allowed values in configuration for the OpenShift SDN network plugin and configuration for the OVN-Kubernetes network plugin.

An example on how to customize the network configuration in vSphere in the network configuration phases section of the installing a cluster on vSphere with network customizations documentation.

Starting with OpenShift 4.15, and only for installations in AWS, it is possible to customize the cluster network MTU configuration in the install-config.yaml.

Starting with OpenShift 4.10, it is possible to modify the MTU after cluster installation: change cluster network MTU after cluster installation. Refer to changing the MTU for the cluster network for additional information.

Root Cause

It is possible to configure the MTU size at installation time modifying the manifest created with the openshift-install create manifests command.

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