Merge pull request #43964 from aojea/kubernetes_cluster_network

kubernetes cluster networking types based on IP address assignment

content/en/docs/concepts/cluster-administration/networking.md

@@ -32,6 +32,34 @@ different approach.
 
 To learn about the Kubernetes networking model, see [here](/docs/concepts/services-networking/).
 
+## Kubernetes IP address ranges
+
+Kubernetes clusters require to allocate non-overlapping IP addresses for Pods, Services and Nodes,
+from a range of available addresses configured in the following components:
+
+- The network plugin is configured to assign IP addresses to Pods.
+- The kube-apiserver is configured to assign IP addresses to Services.
+- The kubelet or the cloud-controller-manager is configured to assign IP addresses to Nodes.
+
+{{< figure src="/docs/images/kubernetes-cluster-network.svg" alt="A figure illustrating the different network ranges in a kubernetes cluster" class="diagram-medium" >}}
+
+## Cluster networking types {#cluster-network-ipfamilies}
+
+Kubernetes clusters, attending to the IP families configured, can be categorized into:
+
+- IPv4 only: The network plugin, kube-apiserver and kubelet/cloud-controller-manager are configured to assign only IPv4 addresses.
+- IPv6 only: The network plugin, kube-apiserver and kubelet/cloud-controller-manager are configured to assign only IPv6 addresses.
+- IPv4/IPv6 or IPv6/IPv4 [dual-stack](/docs/concepts/services-networking/dual-stack/):
+  - The network plugin is configured to assign IPv4 and IPv6 addresses.
+  - The kube-apiserver is configured to assign IPv4 and IPv6 addresses.
+  - The kubelet or cloud-controller-manager is configured to assign IPv4 and IPv6 address.
+  - All components must agree on the configured primary IP family.
+
+Kubernetes clusters only consider the IP families present on the Pods, Services and Nodes objects,
+independently of the existing IPs of the represented objects. Per example, a server or a pod can have multiple
+IP addresses on its interfaces, but only the IP addresses in `node.status.addresses` or `pod.status.ips` are
+considered for implementing the Kubernetes network model and defining the type of the cluster.
+
 ## How to implement the Kubernetes network model
 
 The network model is implemented by the container runtime on each node. The most common container