Merge pull request #89838 from openshift-cherrypick-robot/cherry-pick-89059-to-enterprise-4.19

[enterprise-4.19] OCPBUGS-50848 Section IP address assignment for additional networks missing from docs after reorg

Author: xenolinux

modules/nw-multus-ipam-object.adoc

@@ -13,13 +13,26 @@
 [id="nw-multus-ipam-object_{context}"]
 = Configuration of IP address assignment for a network attachment
 
-The IP address management (IPAM) Container Network Interface (CNI) plugin provides IP addresses for other CNI plugins.
+For additional networks, IP addresses can be assigned using an IP Address Management (IPAM) CNI plugin, which supports various assignment methods, including Dynamic Host Configuration Protocol (DHCP) and static assignment.
 
-You can use the following IP address assignment types:
+The DHCP IPAM CNI plugin responsible for dynamic assignment of IP addresses operates with two distinct components:
 
-- Static assignment.
-- Dynamic assignment through a DHCP server. The DHCP server you specify must be reachable from the additional network.
-- Dynamic assignment through the Whereabouts IPAM CNI plugin.
+* *CNI Plugin*: Responsible for integrating with the Kubernetes networking stack to request and release IP addresses.
+* *DHCP IPAM CNI Daemon*: A listener for DHCP events that coordinates with existing DHCP servers in the environment to handle IP address assignment requests. This daemon is _not_ a DHCP server itself.
+
+For networks requiring `type: dhcp` in their IPAM configuration, ensure the following:
+
+* A DHCP server is available and running in the environment. The DHCP server is external to the cluster and is expected to be part of the customer's existing network infrastructure.
+* The DHCP server is appropriately configured to serve IP addresses to the nodes.
+
+In cases where a DHCP server is unavailable in the environment, it is recommended to use the Whereabouts IPAM CNI plugin instead. The Whereabouts CNI provides similar IP address management capabilities without the need for an external DHCP server.
+
+[NOTE]
+====
+Use the Whereabouts CNI plugin when there is no external DHCP server or where static IP address management is preferred. The Whereabouts plugin includes a reconciler daemon to manage stale IP address allocations.
+====
+
+A DHCP lease must be periodically renewed throughout the container's lifetime, so a separate daemon, the DHCP IPAM CNI Daemon, is required. To deploy the DHCP IPAM CNI daemon, modify the Cluster Network Operator (CNO) configuration to trigger the deployment of this daemon as part of the additional network setup.
 
 ////
 IMPORTANT: If you set the `type` parameter to the `DHCP` value, you cannot set any other parameters.

networking/multiple_networks/secondary_networks/configuring-ip-secondary-nwt.adoc

@@ -6,7 +6,7 @@ include::_attributes/common-attributes.adoc[]
 
 toc::[]
 
-The following sections provide instructions and information for how to configure IP address assignments for secondary networks.
+The following sections give instructions and information for how to configure IP address assignments for secondary networks.
 
 include::modules/nw-multus-ipam-object.adoc[leveloffset=+1]