OSDOCS-11732: Add dummy device as additional network

- https://issues.redhat.com/browse/OSDOCS-11732

Author: jab-rh

modules/nw-multus-dummy-device-object.adoc

@@ -0,0 +1,52 @@
+// Module included in the following assemblies:
+//
+// * networking/multiple_networks/configuring-additional-network.adoc
+
+:_mod-docs-content-type: REFERENCE
+[id="nw-multus-dummy-device-object_{context}"]
+= Configuration for a dummy device additional network
+
+The dummy CNI plugin functions like a loopback device. The plugin is a virtual interface, and you can use the plugin to route the packets to a designated IP address. Unlike a loopback device, the IP address is arbitrary and is not restricted to the `127.0.0.0/8` address range.
+
+The following object describes the configuration parameters for the dummy CNI plugin:
+
+.Dummy device CNI plugin JSON configuration object
+[cols=".^2,.^2,.^6",options="header"]
+|====
+|Field|Type|Description
+
+|`cniVersion`
+|`string`
+|The CNI specification version. The required value is `0.3.1`.
+
+|`name`
+|`string`
+|The value for the `name` parameter that you previously specified for the CNO configuration.
+
+|`type`
+|`string`
+|The name of the CNI plugin that you want to configure. The required value is `dummy`.
+
+|`ipam`
+|`object`
+|The configuration object for the IPAM CNI plugin. The plugin manages the IP address assignment for the attachment definition.
+
+|====
+
+[id="nw-multus-dummy-device-config-example_{context}"]
+== dummy configuration example
+
+The following example configures an additional network named `hostdev-net`:
+
+[source,json]
+----
+{
+  "cniVersion": "0.3.1",
+  "name": "dummy-net",
+  "type": "dummy",
+  "ipam": {
+      "type": "host-local",
+      "subnet": "10.1.1.0/24"
+  }
+}
+----

networking/multiple_networks/secondary_networks/creating-secondary-nwt-other-cni.adoc

@@ -21,6 +21,9 @@ include::modules/nw-multus-bond-cni-object.adoc[leveloffset=+1]
 // Configuration for a host device secondary network
 include::modules/nw-multus-host-device-object.adoc[leveloffset=+1]
 
+// Configure for a dummy additional network
+include::modules/nw-multus-dummy-device-object.adoc[leveloffset=+2]
+
 // Configuration for an VLAN secondary network
 include::modules/nw-multus-vlan-object.adoc[leveloffset=+1]