Configure MTU for Sensor Control Deployments in OpenShift

New
  • Published on Dec 18, 2025
  • 1 minute(s) read
  • AC
 Prev Next

When a Sensor Control virtual machine (VM) is deployed in an OpenShift environment, the system might not detect the correct maximum transmission unit (MTU). This can occur when the VM uses an older Linux kernel.

Incorrect MTU Symptoms

If the MTU is detected incorrectly, you might observe:

  • High levels of TCP retransmissions.

  • SSH sessions that freeze when displaying large outputs.

  • SFTP or FTP transfers that time out after a small amount of data is transferred.

Workaround

To ensure correct MTU handling in this environment:

  1. Set the MTU of the default KubeVirt CNI interface to 1500.

  2. Set the MTU of the machine interface (the interface that connects to the KubeVirt CNI interface) to 1600.

Note: The machine interface must have an MTU higher than the KubeVirt CNI interface to account for the cluster network overlay overhead. The specific overhead is determined by your network plugin. For OVN-Kubernetes, the overhead is 100 bytes.

For more information about changing MTU values in OpenShift, see the Red Hat documentation: Chapter 2. Changing the MTU for the cluster network | Advanced networking | OpenShift Container Platform | 4.18 | Red Hat Documentation