Revert NetworkPolicy v1 docs (#3849)

* Revert "Update configure-namespace-isolation.md (#3758)"

This reverts commit a712b13a3b.

* Revert "Add Configure Namespace Isolation task"

This reverts commit f050c4cc57.

* Revert "Update networkpolicies.md (#3755)"

This reverts commit 15ca8f0b2f.

* Revert "Update NetworkPolicy docs for v1"

This reverts commit 3a158ecf296e3009db1284d69849e7e24479245a.

docs/concepts/services-networking/networkpolicies.md

@@ -2,27 +2,64 @@
 assignees:
 - thockin
 - caseydavenport
-- danwinship
 title: Network Policies
 redirect_from:
 - "/docs/user-guide/networkpolicies/"
 - "/docs/user-guide/networkpolicies.html"
 ---
-{% capture overview %}
-A network policy is a specification of how groups of pods are allowed to communicate with each other and other network endpoints. 
+
+* TOC
+{:toc}
+
+A network policy is a specification of how groups of pods are allowed to communicate with each other and other network endpoints.
 
 `NetworkPolicy` resources use labels to select pods and define whitelist rules which allow traffic to the selected pods in addition to what is allowed by the isolation policy for a given namespace.
-{% endcapture %}
 
-{% capture body %}
+## Prerequisites
+
+You must enable the `extensions/v1beta1/networkpolicies` runtime config in your apiserver to enable this resource.
+
+You must also be using a networking solution which supports `NetworkPolicy` - simply creating the
+resource without a controller to implement it will have no effect.
+
+
+## Configuring Namespace Isolation
+
+By default, all traffic is allowed between all pods (and `NetworkPolicy` resources have no effect).
+
+Isolation can be configured on a per-namespace basis. Currently, only isolation on inbound traffic (ingress) can be defined. When a namespace has been configured to isolate inbound traffic, all traffic to pods in that namespace (even from other pods in the same namespace) will be blocked. `NetworkPolicy` objects can then be added to the isolated namespace to specify what traffic should be allowed.
+
+Ingress isolation can be enabled using an annotation on the Namespace.
+
+```yaml
+kind: Namespace
+apiVersion: v1
+metadata:
+  annotations:
+    net.beta.kubernetes.io/network-policy: |
+      {
+        "ingress": {
+          "isolation": "DefaultDeny"
+        }
+      }
+```
+
+To configure the annotation via `kubectl`:
+
+```shell
+{% raw %}
+kubectl annotate ns <namespace> "net.beta.kubernetes.io/network-policy={\"ingress\": {\"isolation\": \"DefaultDeny\"}}"
+{% endraw %}
+```
+
 ## The `NetworkPolicy` Resource
 
-See the [api-reference](/docs/api-reference/networking/v1/definitions/#_v1_networkpolicy) for a full definition of the resource.
+See the [api-reference](/docs/api-reference/extensions/v1beta1/definitions/#_v1beta1_networkpolicy) for a full definition of the resource.
 
 An example `NetworkPolicy` might look like this:
 
 ```yaml
-apiVersion: networking/v1
+apiVersion: extensions/v1beta1
 kind: NetworkPolicy
 metadata:
   name: test-network-policy
@@ -58,10 +95,6 @@ So, the example NetworkPolicy:
 
 1. allows connections to tcp port 6379 of "role=db" pods in the "default" namespace from any pod in the "default" namespace with the label "role=frontend"
 2. allows connections to tcp port 6379 of "role=db" pods in the "default" namespace from any pod in a namespace with the label "project=myproject"
-{% endcapture %}
 
-{% capture whatsnext %}
-*    For configuration instructions, see [Configuring Namespace Isolation](/docs/tasks/administer-cluster/configure-namespace-isolation).
-*    For more NetworkPolicy examples, see the [NetworkPolicy getting started guide](/docs/getting-started-guides/network-policy/walkthrough).
-{% endcapture %}
-{% include templates/concept.md %}
+See the [NetworkPolicy getting started guide](/docs/getting-started-guides/network-policy/walkthrough) for further examples.
+