[enterprise-4.5] Add information about octavia upgrades impact on Kuryr SDN

modules/installation-osp-kuryr-known-limitations.adoc

@@ -59,3 +59,29 @@ In Go versions 1.13 and later, TCP is used automatically if DNS resolution using
 musl-based containers, including Alpine-based containers, do not support the `use-vc` option.
 ====
 
+[discrete]
+[id="openstack-upgrade-limitations_{context}"]
+== {rh-openstack} upgrade limitations
+
+As a result of the {rh-openstack} upgrade process, the Octavia API might be changed, and upgrades to the Amphora images that are used for load balancers might be required.
+
+You can address API changes on an individual basis.
+
+If the Amphora image is upgraded, the {rh-openstack} operator can handle existing load balancer VMs in two ways:
+
+* Upgrade each VM by triggering a triggering a link:https://access.redhat.com/documentation/en-us/red_hat_openstack_platform/16.0/html/networking_guide/sec-octavia#update-running-amphora-instances[Load Balancer failover].
+
+* Leave responsibility for upgrading the VMs to users.
+
+If the operator takes the first option, there might be short downtimes during failovers.
+
+If the operator takes the second option, the existing load balancers will not support upgraded Octavia
+API features, like UDP listeners. In this case, users must recreate their Services to use these features.
+
+
+[IMPORTANT]
+====
+If {product-title} detects a new Octavia version that supports UDP load balancing, it recreates the DNS Service automatically. The Service recreation ensures that the Service default supports UDP load balancing.
+
+The recreation causes the DNS Service approximately one minute of downtime.
+====