OSDOCS-161612:adds Layer2 EIP limitations for UDN

Author: JoeAldinger

modules/nw-udn-limitations.adoc

@@ -28,4 +28,12 @@ While user-defined networks (UDN) offer highly customizable network configuratio
 
 * *Connectivity limitation*: NodePort services on user-defined networks are not guaranteed isolation. For example, NodePort traffic from a pod to a service on the same node is not accessible, whereas traffic from a pod on a different node succeeds.
 
-* *Unclear error message for IP address exhaustion*: When the subnet of a user-defined network runs out of available IP addresses, new pods fail to start. When this occurs, the following error is returned: `Warning: Failed to create pod sandbox`. This error message does not clearly specify that IP depletion is the cause. To confirm the issue, you can check the *Events* page in the pod's namespace on the {product-title} web console, where an explicit message about subnet exhaustion is reported.
+* *Unclear error message for IP address exhaustion*: When the subnet of a user-defined network runs out of available IP addresses, new pods fail to start. When this occurs, the following error is returned: `Warning: Failed to create pod sandbox`. This error message does not clearly specify that IP depletion is the cause. To confirm the issue, you can check the *Events* page in the pod's namespace on the {product-title} web console, where an explicit message about subnet exhaustion is reported.
+
+* *Layer2 egress IP limitations*:
+
+** Egress IP does not work without a default gateway.
+
+** Egress IP does not work on Google Cloud Platform (GCP).
+
+** Egress IP does not work with multiple gateways and instead will forward all traffic to one gateway.