Merge pull request #81987 from stevsmit/OCPBUGS-18684

Adds note that MEG and egress are incompatible

Author: stevsmit

modules/configuring-ovnk-use-second-ovs-bridge.adoc

@@ -10,6 +10,11 @@ You can create an additional or _secondary_ Open vSwitch (OVS) bridge, `br-ex1`,
 
 Consider a use case for pods impacted by the Multiple External Gateways (MEG) feature and you want to egress traffic to a different interface, for example `br-ex1`, on a node. Egress traffic for pods not impacted by MEG get routed to the default OVS `br-ex` bridge.
 
+[IMPORTANT]
+====
+Currently, MEG is unsupported for use with other egress features, such as egress IP, egress firewalls, or egress routers. Attempting to use MEG with egress features like egress IP can result in routing and traffic flow conflicts. This occurs because of how OVN-Kubernetes handles routing and source network address translation (SNAT). This results in inconsistent routing and might break connections in some environments where the return path must patch the incoming path.
+====
+
 You must define the additional bridge in an interface definition of a machine configuration manifest file. The Machine Config Operator uses the manifest to create a new file at `/etc/ovnk/extra_bridge` on the host. The new file includes the name of the network interface that the additional OVS bridge configures for a node.
 
 After you create and edit the manifest file, the Machine Config Operator completes tasks in the following order: