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OSDOCS-16832: MNW-1: Multiple Networks Core Concepts and VRF Overview
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“Shauna Diaz”
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@@ -7,3 +7,5 @@ include::_attributes/common-attributes.adoc[]
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toc::[]
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include::modules/cnf-about-virtual-routing-and-forwarding.adoc[leveloffset=+1]
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include::modules/cnf-benefits-secondary-networks-telco-ops.adoc[leveloffset=+2]
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@@ -6,82 +6,18 @@ include::_attributes/common-attributes.adoc[]
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toc::[]
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By default, OVN-Kubernetes serves as the Container Network Interface (CNI) of an {product-title} cluster. With OVN-Kubernetes as the default CNI of a cluster, {product-title} administrators or users can leverage xref:../../networking/multiple_networks/primary_networks/about-user-defined-networks.adoc#about-user-defined-networks[user-defined networks (UDNs)] or xref:../../networking/multiple_networks/primary_networks/about-primary-nwt-nad.adoc#understanding-multiple-networks[NetworkAttachmentDefinition (NADs)] to create one, or multiple, default networks that handle all ordinary network traffic of the cluster. Both user-defined networks and Network Attachment Definitions can serve as the following network types:
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[role="_abstract"]
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{product-title} administrators and users can use user-defined networks (UDNs) or `NetworkAttachmentDefinition` (NADs) to define the networks that handle all of the ordinary network traffic of the cluster.
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* *Primary networks*: Act as the primary network for the pod. By default, all traffic passes through the primary network unless a pod route is configured to send traffic through other networks.
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* *Secondary networks*: Act as secondary, non-default networks for a pod. Secondary networks provide separate interfaces dedicated to specific traffic types or purposes. Only pod traffic that is explicitly configured to use a secondary network is routed through its interface.
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The following diagram shows a cluster that has an existing default network infrastructure that uses a physical network interface, `eth0`, to connect to two namespaces. Pods or virtual machines (VMs) in one namespace run in isolation from pods or VMs in the other namespace. You can create only one primary network but multiple secondary networks for each namespace.
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.Diagram showing namespaces with multiple secondary UDNs
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image::501_OpenShift_UDN_pri_sec_0925.png[Diagram showing namespaces with multiple secondary UDNs]
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During cluster installation, {product-title} administrators can configure alternative default secondary pod networks by leveraging the Multus CNI plugin. With Multus, multiple CNI plugins such as ipvlan, macvlan, or Network Attachment Definitions can be used together to serve as secondary networks for pods.
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[NOTE]
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====
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User-defined networks are only available when OVN-Kubernetes is used as the CNI. They are not supported for use with other CNIs.
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====
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You can define an secondary network based on the available CNI plugins and attach one or more of these networks to your pods. You can define more than one secondary network for your cluster depending on your needs. This gives you flexibility when you configure pods that deliver network functionality, such as switching or routing.
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For a complete list of supported CNI plugins, see xref:additional-networks-provided_understanding-multiple-networks["Secondary networks in {product-title}"].
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For information about user-defined networks, see xref:../../networking/multiple_networks/primary_networks/about-user-defined-networks.adoc#about-user-defined-networks[About user-defined networks (UDNs)].
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For information about Network Attachment Definitions, see xref:../../networking/multiple_networks/primary_networks/about-primary-nwt-nad.adoc#understanding-multiple-networks[Creating primary networks using a NetworkAttachmentDefinition].
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[id="additional-network-considerations"]
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== Usage scenarios for a secondary network
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You can use a secondary network in situations where network isolation is needed, including data plane and control plane separation. Isolating network traffic is useful for the following performance and security reasons:
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. Performance
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+
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**Traffic management**: You can send traffic on two different planes to manage how much traffic is along each plane.
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. Security
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**Network isolation**: You can send sensitive traffic onto a network plane that is managed specifically for security considerations, and you can separate private data that must not be shared between tenants or customers.
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All of the pods in the cluster still use the cluster-wide default network to maintain connectivity across the cluster. Every pod has an `eth0` interface that is attached to the cluster-wide pod network. You can view the interfaces for a pod by using the `oc exec -it <pod_name> \-- ip a` command. If you add secondary network interfaces that use Multus CNI, they are named `net1`,
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`net2`, ..., `netN`.
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To attach secondary network interfaces to a pod, you must create configurations that define how the interfaces are attached. You specify each interface by using either a `UserDefinedNetwork` custom resource (CR) or a `NetworkAttachmentDefinition` CR. A CNI configuration inside each of these CRs defines how that interface is created.
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For more information about creating a `UserDefinedNetwork` CR, see xref:../../networking/multiple_networks/primary_networks/about-user-defined-networks.adoc#about-user-defined-networks[About user-defined networks].
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For more information about creating a NetworkAttachmentDefinition CR, see xref:../../networking/multiple_networks/primary_networks/about-primary-nwt-nad.adoc#understanding-multiple-networks[Creating primary networks using a NetworkAttachmentDefinition].
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[id="additional-networks-provided_{context}"]
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== Secondary networks in {product-title}
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{product-title} provides the following CNI plugins for creating secondary
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networks in your cluster:
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* *bridge*: xref:../../networking/multiple_networks/secondary_networks/creating-secondary-nwt-other-cni.adoc#nw-multus-bridge-object_configuring-additional-network-cni[Configure a bridge-based secondary network] to allow pods on the same host to communicate with each other and the host.
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* *bond-cni*: xref:../../networking/multiple_networks/secondary_networks/creating-secondary-nwt-other-cni.adoc#nw-multus-bond-cni-object_configuring-additional-network-cni[Configure a Bond CNI secondary network] to provide a method for aggregating multiple network interfaces into a single logical _bonded_ interface.
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* *host-device*: xref:../../networking/multiple_networks/secondary_networks/creating-secondary-nwt-other-cni.adoc#nw-multus-host-device-object_configuring-additional-network-cni[Configure a host-device secondary network] to allow pods access to a physical Ethernet network device on the host system.
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* *ipvlan*: xref:../../networking/multiple_networks/secondary_networks/creating-secondary-nwt-other-cni.adoc#nw-multus-ipvlan-object_configuring-additional-network-cni[Configure an ipvlan-based secondary network] to allow pods on a host to communicate with other hosts and pods on those hosts, similar to a macvlan-based secondary network. Unlike a macvlan-based secondary network, each pod shares the same MAC address as the parent physical network interface.
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* *vlan*: xref:../../networking/multiple_networks/secondary_networks/creating-secondary-nwt-other-cni.adoc#nw-multus-vlan-object_configuring-additional-network-cni[Configure a VLAN-based secondary network] to allow VLAN-based network isolation and connectivity for pods.
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* *macvlan*: xref:../../networking/multiple_networks/secondary_networks/creating-secondary-nwt-other-cni.adoc#nw-multus-macvlan-object_configuring-additional-network-cni[Configure a macvlan-based secondary network] to allow pods on a host to communicate with other hosts and pods on those hosts by using a physical network interface. Each pod that is attached to a macvlan-based secondary network is provided a unique MAC address.
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* *TAP*: xref:../../networking/multiple_networks/secondary_networks/creating-secondary-nwt-other-cni.adoc#nw-multus-tap-object_configuring-additional-network-cni[Configure a TAP-based secondary network] to create a tap device inside the container namespace. A TAP device enables user space programs to send and receive network packets.
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* *SR-IOV*: xref:../../networking/hardware_networks/about-sriov.adoc#about-sriov[Configure an SR-IOV based secondary network] to allow pods to attach to a virtual function (VF) interface on SR-IOV capable hardware on the host system.
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* *route-override*: xref:../../networking/multiple_networks/secondary_networks/creating-secondary-nwt-other-cni.adoc#nw-route-override-cni_configuring-additional-network-cni[Configure a `route-override` based secondary network] to allow pods to override and set routes.
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include::modules/understanding-multiple-networks-con.adoc[leveloffset=+1]
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// UserDefinedNetwork and NetworkAttachmentDefinition support matrix
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include::modules/support-matrix-for-udn-nad.adoc[leveloffset=+1]
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[id="additional-resources_understanding-multiple-networks"]
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[role="_additional-resources"]
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.Additional resources
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== Additional resources
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* xref:../../networking/multiple_networks/primary_networks/about-user-defined-networks.adoc#about-user-defined-networks[About user-defined networks (UDNs)]
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* xref:../../networking/multiple_networks/primary_networks/about-primary-nwt-nad.adoc#understanding-multiple-networks[Creating primary networks using a NetworkAttachmentDefinition]
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* xref:../../networking/ovn_kubernetes_network_provider/enabling-multicast.adoc#nw-ovn-kubernetes-enabling-multicast[Enabling multicast for a project]
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@@ -0,0 +1,75 @@
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:_mod-docs-content-type: ASSEMBLY
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[id="use-cases-secondary-network"]
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= Use cases for a secondary network
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include::_attributes/common-attributes.adoc[]
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:context: use-cases-secondary-network
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toc::[]
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[role="_abstract"]
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You can use a secondary network in situations where you require network isolation, including data plane and control plane separation.
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Isolating network traffic is useful for the following performance and security reasons:
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* Performance
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+
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**Traffic management**: You can send traffic on two different planes to manage how much traffic is along each plane.
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* Security
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+
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**Network isolation**: You can send sensitive traffic onto a network plane that is managed specifically for security considerations, and you can separate private data that must not be shared between tenants or customers.
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All of the pods in the cluster still use the cluster-wide default network to maintain connectivity across the cluster. Every pod has an `eth0` interface that is attached to the cluster-wide pod network. You can view the interfaces for a pod by using the `oc exec -it <pod_name> \-- ip a` command. If you add secondary network interfaces that use the Multus Container Network Interface (CNI). These secondary networks are named `net1`, `net2`, and so on.
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To attach secondary network interfaces to a pod, you must create configurations that define how the interfaces are attached. Use either a `UserDefinedNetwork` custom resource (CR) or a `NetworkAttachmentDefinition` CR to specify each interface. A CNI configuration inside each of these CRs defines how that interface is created.
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//assembly not further modularized because the following section acts as an index page:
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[id="additional-networks-provided_{context}"]
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== Secondary networks in {product-title}
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{product-title} provides the following CNI plugins for creating secondary networks in your cluster:
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* *bridge*: To configure a bridge-based secondary network to allow pods on the same host to communicate with each other and the host, use the following procedure:
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** xref:../../networking/multiple_networks/secondary_networks/creating-secondary-nwt-other-cni.adoc#nw-multus-bridge-object_configuring-additional-network-cni[Configure a bridge-based secondary network]
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* *bond-cni*: To provide a method for aggregating multiple network interfaces into a single logical _bonded_ interface, use the following procedure:
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** xref:../../networking/multiple_networks/secondary_networks/creating-secondary-nwt-other-cni.adoc#nw-multus-bond-cni-object_configuring-additional-network-cni[Configure a Bond CNI secondary network]
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* *host-device*: To allow pods access to a physical Ethernet network device on the host system, use the following procedure:
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** xref:../../networking/multiple_networks/secondary_networks/creating-secondary-nwt-other-cni.adoc#nw-multus-host-device-object_configuring-additional-network-cni[Configure a host-device secondary network]
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* *ipvlan*: Allow pods on a host to communicate with other hosts and pods on those hosts, similar to a macvlan-based secondary network. Unlike a macvlan-based secondary network, each pod shares the same MAC address as the parent physical network interface. Use the following procedure:
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** xref:../../networking/multiple_networks/secondary_networks/creating-secondary-nwt-other-cni.adoc#nw-multus-ipvlan-object_configuring-additional-network-cni[Configure an ipvlan-based secondary network]
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* *VLAN*: To allow VLAN-based network isolation and connectivity for pods, use the following procedure:
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** xref:../../networking/multiple_networks/secondary_networks/creating-secondary-nwt-other-cni.adoc#nw-multus-vlan-object_configuring-additional-network-cni[Configure a VLAN-based secondary network]
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* *macvlan*: To allow pods on a host to communicate with other hosts and pods on those hosts by using a physical network interface. Each pod that is attached to a macvlan-based secondary network is provided a unique MAC address:
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** xref:../../networking/multiple_networks/secondary_networks/creating-secondary-nwt-other-cni.adoc#nw-multus-macvlan-object_configuring-additional-network-cni[Configure a macvlan-based secondary network]
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* *TAP*: A TAP device enables user space programs to send and receive network packets. To create a TAP device inside the container namespace, use the following procedure:
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** xref:../../networking/multiple_networks/secondary_networks/creating-secondary-nwt-other-cni.adoc#nw-multus-tap-object_configuring-additional-network-cni[Configure a TAP-based secondary network]
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* *SR-IOV*: To allow pods to attach to a virtual function (VF) interface on SR-IOV capable hardware on the host system.
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** xref:../../networking/hardware_networks/about-sriov.adoc#about-sriov[Configure an SR-IOV based secondary network]
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* *route-override*: To allow pods to override and set routes, use the following procedure:
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** xref:../../networking/multiple_networks/secondary_networks/creating-secondary-nwt-other-cni.adoc#nw-route-override-cni_configuring-additional-network-cni[Configure a `route-override` based secondary network]
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// UserDefinedNetwork and NetworkAttachmentDefinition support matrix
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include::modules/support-matrix-for-udn-nad.adoc[leveloffset=+1]
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[id="additional-resources_use-cases-secondary-network"]
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[role="_additional-resources"]
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== Additional resources
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* xref:../../networking/ovn_kubernetes_network_provider/enabling-multicast.adoc#nw-ovn-kubernetes-enabling-multicast[Enabling multicast for a project]
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