OpenShift SDN, a component of Red Hat OpenShift Networking, is a network plugin that uses software-defined networking (SDN) to create a unified network for your cluster. This network allows communication between pods across the OpenShift Container Platform. OpenShift SDN manages this network by configuring an overlay network using Open vSwitch (OVS).
OpenShift SDN has been deprecated since version 4.14 and will no longer be supported starting with version 4.17. Therefore, if your cluster is using OpenShift SDN, you must migrate to OVN-Kubernetes before upgrading to any minor OpenShift version beyond 4.16.
Migrating to OVN-Kubernetes for Azure Red Hat OpenShift
If your Azure Red Hat OpenShift (ARO) cluster is using the OpenShift SDN network plugin, you must migrate to the OVN-Kubernetes plugin before updating to version 4.17.
OVN-Kuberentes has been the default network plugin starting with ARO version 4.11. If you installed your cluster with version 4.11 or later, you likely don't need to perform a migration.