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About Single Root I/O Virtualization (SR-IOV) hardware networks

The Single Root I/O Virtualization (SR-IOV) specification is a standard for a type of PCI device assignment that can share a single device with multiple pods.

You can configure a Single Root I/O Virtualization (SR-IOV) device in your cluster by using the SR-IOV Operator.

SR-IOV can segment a compliant network device, recognized on the host node as a physical function (PF), into multiple virtual functions (VFs). The VF is used like any other network device. The SR-IOV network device driver for the device determines how the VF is exposed in the container:

  • netdevice driver: A regular kernel network device in the netns of the container

  • vfio-pci driver: A character device mounted in the container

You can use SR-IOV network devices with additional networks on your OKD cluster installed on bare metal or OpenStack infrastructure for applications that require high bandwidth or low latency.

The SR-IOV Network Operator is supported on the following platforms:

  • Bare metal

  • OpenStack

For a list of devices, such as network interface controllers (NICs) that OKD supports, see Red Hat certified hardware on the Red Hat Ecosystem Catalog. The following example, finds the Intel X710 network adapter:

  1. From the Red Hat certified hardware webpage, click Explore from the Components tile.

  2. From the Provider drop-down menu, click the Intel Corporation checkbox.

  3. From the Platform drop-down menu, click the Red Hat OpenShift Container Platform checkbox.

  4. Find the Intel® Ethernet Server Adapter X710 network adapter from the list and then click on its tile. A new webpage opens that shows information for the network adapter.

You can configure multi-network policies for SR-IOV networks. The support for this is technology preview and SR-IOV additional networks are only supported with kernel NICs. They are not supported for Data Plane Development Kit (DPDK) applications.

Creating multi-network policies on SR-IOV networks might not deliver the same performance to applications compared to SR-IOV networks without a multi-network policy configured.

Multi-network policies for SR-IOV network is a Technology Preview feature only. Technology Preview features are not supported with Red Hat production service level agreements (SLAs) and might not be functionally complete. Red Hat does not recommend using them in production. These features provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process.

For more information about the support scope of Red Hat Technology Preview features, see Technology Preview Features Support Scope.

You can enable SR-IOV on a node by using the following command:

$ oc label node <node_name> feature.node.kubernetes.io/network-sriov.capable="true"

Additional resources

Components that manage SR-IOV network devices

The SR-IOV Network Operator creates and manages the components of the SR-IOV stack. The Operator performs the following functions:

  • Orchestrates discovery and management of SR-IOV network devices

  • Generates NetworkAttachmentDefinition custom resources for the SR-IOV Container Network Interface (CNI)

  • Creates and updates the configuration of the SR-IOV network device plugin

  • Creates node specific SriovNetworkNodeState custom resources

  • Updates the spec.interfaces field in each SriovNetworkNodeState custom resource

The Operator provisions the following components:

SR-IOV network configuration daemon

A daemon set that is deployed on worker nodes when the SR-IOV Network Operator starts. The daemon is responsible for discovering and initializing SR-IOV network devices in the cluster.

SR-IOV Network Operator webhook

A dynamic admission controller webhook that validates the Operator custom resource and sets appropriate default values for unset fields.

SR-IOV Network resources injector

A dynamic admission controller webhook that provides functionality for patching Kubernetes pod specifications with requests and limits for custom network resources such as SR-IOV VFs. The SR-IOV network resources injector adds the resource field to only the first container in a pod automatically.

SR-IOV network device plugin

A device plugin that discovers, advertises, and allocates SR-IOV network virtual function (VF) resources. Device plugins are used in Kubernetes to enable the use of limited resources, typically in physical devices. Device plugins give the Kubernetes scheduler awareness of resource availability, so that the scheduler can schedule pods on nodes with sufficient resources.

SR-IOV CNI plugin

A CNI plugin that attaches VF interfaces allocated from the SR-IOV network device plugin directly into a pod.

SR-IOV InfiniBand CNI plugin

A CNI plugin that attaches InfiniBand (IB) VF interfaces allocated from the SR-IOV network device plugin directly into a pod.

The SR-IOV Network resources injector and SR-IOV Network Operator webhook are enabled by default and can be disabled by editing the default SriovOperatorConfig CR. Use caution when disabling the SR-IOV Network Operator Admission Controller webhook. You can disable the webhook under specific circumstances, such as troubleshooting, or if you want to use unsupported devices.

Additional resources

Next steps