TLS handshake fails due to large packets discarded for Openshift 4 on Azure

Solution Verified - Updated -

Issue

  • TLS handshake errors occur although TCP communication is possible. A traffic capture shows large packets being discarded (see "Diagnostic Steps").
  • Unexpected ICMP fragmentation needed messages are received for direct communications happening between OpenShift nodes but without vxlan encapsulation. Requested MTU is lower than the one set in both ends and/or required by any intermediate element.
  • Routing cache shows bad entries as described in "Diagnostic Steps".
  • After some time, the OpenShift Cluster becomes very slow and many operators start to become unhealthy (degraded state).

Environment

  • Red Hat OpenShift Container Platform (RHOCP)
    • OpenShift SDN
      • 4.6
      • 4.7
    • OVN-Kubernetes
      • 4.8
      • 4.9
      • 4.10
  • Azure

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