Merge pull request #70905 from stevsmit/OCPBUGS-16661

Adds note for when using multicast with network policies

Author: stevsmit

modules/nw-about-multicast.adoc

@@ -20,8 +20,8 @@ With IP multicast, data is broadcast to many IP addresses simultaneously.
 
 [IMPORTANT]
 ====
-At this time, multicast is best used for low-bandwidth coordination or service
-discovery and not a high-bandwidth solution.
+* At this time, multicast is best used for low-bandwidth coordination or service discovery and not a high-bandwidth solution.
+* By default, network policies affect all connections in a namespace. However, multicast is unaffected by network policies. If multicast is enabled in the same namespace as your network policies, it is always allowed, even if there is a `deny-all` network policy. Cluster administrators should consider the implications to the exemption of multicast from network policies before enabling it.
 ====
 
 Multicast traffic between {product-title} pods is disabled by default. If you are using the {sdn} network plugin, you can enable multicast on a per-project basis.
@@ -49,4 +49,4 @@ ifeval::["{context}" == "ovn-kubernetes-enabling-multicast"]
 endif::[]
 ifdef::sdn[]
 :!sdn:
-endif::sdn[]
+endif::sdn[]