(WIP) OSDOCS-13187:Manually setting the MTU value #93116
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@tedaveryredhat: This pull request references OSDOCS-13187 which is a valid jira issue. Warning: The referenced jira issue has an invalid target version for the target branch this PR targets: expected the story to target the "4.20.0" version, but no target version was set. In response to this:
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🤖 Wed May 07 19:20:19 - Prow CI generated the docs preview: https://93116--ocpdocs-pr.netlify.app/microshift/latest/microshift_networking/microshift-cni.html |
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@tedaveryredhat: This pull request references OSDOCS-13187 which is a valid jira issue. Warning: The referenced jira issue has an invalid target version for the target branch this PR targets: expected the story to target the "4.20.0" version, but no target version was set. In response to this:
Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the openshift-eng/jira-lifecycle-plugin repository. |
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| When you start {microshift-short} in a virtual machine using OpenShift Virtualization that uses the pod network as the primary interface, the default MTU value is not detected. Therefore, specifying the MTU value manually in `/etc/microshift/ovn.yaml` is required. |
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I dont see how its related to OpenShift Virtualization,it concerns every environment when the MTU is not the default 1500, and this behaviour changed in 4.19 -
when MTU is not set in the ovn.yaml we get it from the default route interface.
see openshift/microshift#4315
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Would this text need to be revised to "If you do not specify the MTU value in /etc/microshift/ovn.yaml, then the value from the default route interface is used."
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Here's my suggestion:
The MTU of the OVN overlay networking in MicroShift must be 100 bytes smaller than the MTU of the base network.
If no MTU value is configured, MicroShift auto-configures this using the mtu size of the default gateway (IPV4 or V6) of the host.
In case the auto-configuration does not work correctly, the MTU size can be configured manually. Example: if the MTU size of the network is 9000, the OVN MTU size must be set to 8900.
Version(s):
4.19
Issue:
https://issues.redhat.com/browse/OSDOCS-13187
Link to docs preview:
https://93116--ocpdocs-pr.netlify.app/microshift/latest/microshift_networking/microshift-cni.html
QE review: