Upgrade to OCP 4.14 using OVN-Kubernetes leaves the cluster severely degraded when networks overlap the 100.88.0.0/16 subnet

Solution Verified - Updated -

Issue

  • Planning to upgrade OpenShift cluster using OVN-Kubernetes CNI plugin to 4.14, but upon checking the official documentation 1 and 2 it raises concerns since cluster is configured with network ranges that conflict with the new OVN transit switch CIDR.

  • Cluster upgraded and now noticing severe network performance issues and multiple issues in the cluster general functionality, with cluster operators flipping or stuck to degraded state.

  • Errors in OVNKube: illegal network configuration: transit switch subnet "100.88.0.0/16" overlaps service subnet "100.88.0.0/16" or similar messaging.

Environment

  • Red Hat OpenShift Container Platform (RHOCP)
    • 4.14
    • OVN-Kubernetes CNI (OVN-K8S)

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