Merge pull request #92515 from dfitzmau/OCPBUGS-54148-12

[enterprise-4.12] OCPBUGS-54148-sdn: Added PTP and OVNK limitation to SDN ddocs

Author: dfitzmau

modules/nw-ovn-kubernetes-migration-about.adoc

@@ -50,6 +50,8 @@ While the OVN-Kubernetes network plugin implements many of the capabilities pres
 
 * If your cluster or surrounding network uses any part of the `100.64.0.0/16` address range, you must choose another unused IP range by specifying the `v4InternalSubnet` spec under the `spec.defaultNetwork.ovnKubernetesConfig` object definition. OVN-Kubernetes uses the IP range `100.64.0.0/16` internally by default.
 
+* If your `openshift-sdn` cluster with Precision Time Protocol (PTP) uses the User Datagram Protocol (UDP) for hardware time stamping and you migrate to the OVN-Kubernetes plugin, the hardware time stamping cannot be applied to primary interface devices, such as an Open vSwitch (OVS) bridge. As a result, UDP version 4 configurations cannot work with a `br-ex` interface.
+
 The following sections highlight the differences in configuration between the aforementioned capabilities in OVN-Kubernetes and OpenShift SDN network plugins.
 
 [discrete]