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Clean up services-networking/_index.md
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‎content/en/docs/concepts/services-networking/_index.md

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@@ -9,58 +9,53 @@ description: >
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The Kubernetes network model is built out of several pieces:
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* Each [Pod](/docs/concepts/workloads/pods/) in a cluster gets its
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own unique cluster-wide IP address.
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* A pod has its own private network namespace which is shared by
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all of the containers within the pod. Processes running in
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different containers in the same pod can communicate with each
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other over `localhost`.
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* The _pod network_ (also called a cluster network) handles communication
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between pods. It ensures that (barring intentional network
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segmentation):
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* All pods can communicate with all other pods, whether they are
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on the same [node](/docs/concepts/architecture/nodes/) or on
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different nodes. Pods can communicate with each other
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directly, without the use of proxies or address translation
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(NAT).
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* (On Windows, this rule does not apply to host-network pods.)
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* Agents on a node (such as system daemons, or kubelet) can
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communicate with all pods on that node.
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* The [Service](/docs/concepts/services-networking/service/) API
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lets you provide a stable (long lived) IP address or hostname for a service implemented
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by one or more backend pods, where the individual pods making up
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the service can change over time.
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* Kubernetes automatically manages
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[EndpointSlice](/docs/concepts/services-networking/endpoint-slices/)
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objects to provide information about the pods currently
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backing a Service.
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* A service proxy implementation monitors the `Service` and
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`EndpointSlice` objects, and programs the data plane to route
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service traffic to its backends, by using operating system or
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cloud provider APIs to intercept or rewrite packets.
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* The [Gateway](/docs/concepts/services-networking/gateway/) API
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(or its predecessor,
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[Ingress](/docs/concepts/services-networking/ingress/)) allows
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you to make Services accessible to clients that are outside the cluster.
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* A simpler, but less-configurable, mechanism for cluster
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ingress is available via the Service API's [`type:
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LoadBalancer`](/docs/concepts/services-networking/service/#loadbalancer),
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when using a supported {{< glossary_tooltip term_id="cloud-provider">}}.
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* [NetworkPolicy](/docs/concepts/services-networking/network-policies) is a built-in
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Kubernetes API that
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allows you to control traffic between pods, or between pods and
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the outside world.
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* Each [pod](/docs/concepts/workloads/pods/) in a cluster gets its
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own unique cluster-wide IP address.
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* A pod has its own private network namespace which is shared by
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all of the containers within the pod. Processes running in
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different containers in the same pod can communicate with each
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other over `localhost`.
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* The _pod network_ (also called a cluster network) handles communication
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between pods. It ensures that (barring intentional network segmentation):
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* All pods can communicate with all other pods, whether they are
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on the same [node](/docs/concepts/architecture/nodes/) or on
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different nodes. Pods can communicate with each other
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directly, without the use of proxies or address translation (NAT).
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On Windows, this rule does not apply to host-network pods.
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* Agents on a node (such as system daemons, or kubelet) can
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communicate with all pods on that node.
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* The [Service](/docs/concepts/services-networking/service/) API
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lets you provide a stable (long lived) IP address or hostname for a service implemented
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by one or more backend pods, where the individual pods making up
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the service can change over time.
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* Kubernetes automatically manages
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[EndpointSlice](/docs/concepts/services-networking/endpoint-slices/)
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objects to provide information about the pods currently backing a Service.
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* A service proxy implementation monitors the set of Service and
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EndpointSlice objects, and programs the data plane to route
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service traffic to its backends, by using operating system or
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cloud provider APIs to intercept or rewrite packets.
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* The [Gateway](/docs/concepts/services-networking/gateway/) API
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(or its predecessor, [Ingress](/docs/concepts/services-networking/ingress/))
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allows you to make Services accessible to clients that are outside the cluster.
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* A simpler, but less-configurable, mechanism for cluster
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ingress is available via the Service API's
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[`type: LoadBalancer`](/docs/concepts/services-networking/service/#loadbalancer),
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when using a supported {{< glossary_tooltip term_id="cloud-provider">}}.
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* [NetworkPolicy](/docs/concepts/services-networking/network-policies) is a built-in
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Kubernetes API that allows you to control traffic between pods, or between pods and
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the outside world.
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In older container systems, there was no automatic connectivity
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between containers on different hosts, and so it was often necessary
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corresponding functionality is provided by external components, some
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of which are optional:
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* Pod network namespace setup is handled by system-level software
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implementing the [Container Runtime
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Interface](/docs/concepts/architecture/cri.md).
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* The pod network itself is managed by a [pod network
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implementation](/docs/concepts/cluster-administration/addons/#networking-and-network-policy).
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On Linux, most container runtimes use the
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{{< glossary_tooltip text="Container Networking Interface (CNI)" term_id="cni" >}}
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to interact with the pod network implementation, so these
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implementations are often called _CNI plugins_.
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* Kubernetes provides a default implementation of service proxying,
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called {{< glossary_tooltip term_id="kube-proxy">}}, but some pod
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network implementations instead use their own service proxy that
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is more tightly integrated with the rest of the implementation.
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* NetworkPolicy is generally also implemented by the pod network
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implementation. (Some simpler pod network implementations don't
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implement NetworkPolicy, or an administrator may choose to
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configure the pod network without NetworkPolicy support. In these
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cases, the API will still be present, but it will have no effect.)
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* There are many [implementations of the Gateway
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API](https://gateway-api.sigs.k8s.io/implementations/), some of
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which are specific to particular cloud environments, some more
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focused on "bare metal" environments, and others more generic.
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* Pod network namespace setup is handled by system-level software implementing the
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[Container Runtime Interface](/docs/concepts/architecture/cri.md).
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* The pod network itself is managed by a
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[pod network implementation](/docs/concepts/cluster-administration/addons/#networking-and-network-policy).
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On Linux, most container runtimes use the
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{{< glossary_tooltip text="Container Networking Interface (CNI)" term_id="cni" >}}
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to interact with the pod network implementation, so these
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implementations are often called _CNI plugins_.
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* Kubernetes provides a default implementation of service proxying,
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called {{< glossary_tooltip term_id="kube-proxy">}}, but some pod
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network implementations instead use their own service proxy that
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is more tightly integrated with the rest of the implementation.
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* NetworkPolicy is generally also implemented by the pod network
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implementation. (Some simpler pod network implementations don't
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implement NetworkPolicy, or an administrator may choose to
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configure the pod network without NetworkPolicy support. In these
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cases, the API will still be present, but it will have no effect.)
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* There are many [implementations of the Gateway API](https://gateway-api.sigs.k8s.io/implementations/),
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some of which are specific to particular cloud environments, some more
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focused on "bare metal" environments, and others more generic.
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## {{% heading "whatsnext" %}}
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The [Connecting Applications with Services](/docs/tutorials/services/connect-applications-service/) tutorial lets you learn about Services and Kubernetes networking with a hands-on example.
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The [Connecting Applications with Services](/docs/tutorials/services/connect-applications-service/)
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tutorial lets you learn about Services and Kubernetes networking with a hands-on example.
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[Cluster Networking](/docs/concepts/cluster-administration/networking/) explains how to set
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up networking for your cluster, and also provides an overview of the technologies involved.

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