Support Napatech LinkVirtualization SmartNICs

Napatech LinkVirtualization SmartNICs offload network traffic switching, QoS, and tunnel encapsulation/decapsulation functions from the OVS running on the hypervisor to the on-board silicon. This spec proposes to update the Nova and Neutron source code to include support for a new VIF type corresponding to the virtual devices exposed by the LinkVirtualization SmartNIC.

Problem description

Napatech SmartNICs can offload several computational resource intensive tasks from the hypervisor, such as packet switching, QoS enforcement, and V(x)LAN tunnel encapsulation/decapsulation. Upstream and Out of tree OVS implementations can leverage these offloads when using dpdk via DPDK port representors (

Data processing, like encryption and compression, can be extremely intensive when performed in software and require a tremendous amount of CPU cores. By offloading these functions to accelerated NIC hardware it is possible to significantly increase performance and free CPU cores to support more virtual functions on the same server.

To achive those goals Napatech provides SmartNIC Solution Virtual Switch Acceleration.

Napatech Getting Started Guide will provide details regarding Napatech SmartNIC solution for hardware offload: * OS Preparation * Compiling and Installing DPDK with the Napatech PMD * Running OVS-DPDK * OVS-DPDK Configuration Examples

Nova and os-vif currently support kernel-based VF representors, but not the DPDK VF representors which leverage vhost-user socket. This spec seeks to address this gap.

Use Cases

  • An end user of Napatech SmartNIC should be able to support Napatech SmartNICs out-of-the-box.

  • Other SmartNICs using OvS-DPDK representor ports should also work.

Proposed change

  • We propose to extend the OpenvSwitch driver with a new VNIC type VNIC_VIRTIO_FORWARDER and the related VIF handling function nova_to_osvif_vif(). A method which handles vhostuser VIF type should handle the new VNIC type by setting an appropriate datapath, representor port profile, vhostuser vif type, OVS plugin, and datapath offload settings. OpenvSwitch driver should be able to set the DPDK representor socket path for virtio-forwarder vnic type:

  • We propose to extend vif type OVS attribute OVS_DPDK_PORT_TYPES with a new port type dpdk.

  • We propose to update the OvsPlugin class to support plug and unplug of OVS DPDK representor ports os_vif OVSPlugin code.

Appropriate methods plug() and unplug() should be extended with ability to plug VF if vif has VIFPortProfileOVSRepresentor port profile for VIFVHostUser.

  • _plug_vf() method should be extended with formula VF_NUM=ID*8+VF to calculate VF number based on the input PCI slot.

  • update_device_mtu() method will be extended with OVS_DPDK_INTERFACE_TYPE interface support to have ability update MTU configuration for port on the OVS layer.

  • We propose Unit/Functional tests pertinent to the proposed changes.

  • The NT200A02 and NT50B01 SmartNics with Link-Virtualization™ software will provide support of the hardware-based solution for full Open vSwitch (OVS) offload.

  • Napatech will a provide document with NT NIC hardware offloading configuration in the OpenStack. This documentation will consist configuration steps, requirements, links on the Napatech portal with software and additional specific documentations. This document will be created under Neutron project.



Data model impact


REST API impact


Security impact


Notifications impact


Other end user impact


Performance Impact

Users will see a significant network performance increase when running over the hardware offloaded data-plane compared kernel-ovs and traditional vhost-user.

Other deployer impact

In line with other SmartNIC offerings, the deployer will have to configure OVS-DPDK following the SmartNIC producer guidelines and update the PCI device_spec configuration.

Developer impact


Upgrade impact




  • Oleksii Butenko (obu-plv)

  • Danylo Vodopianov (dvo-plv)

  • Justas Poderys (justas_napa on IRC and Gerrit)

Feature Liaison

  • Sean Mooney (sean-k-mooney)

Work Items

  • Extend Openvswitch driver with Virtio-Forwarder VIF type support

  • Add Virtio-Forwarder VIF type for Qos support

  • Add new OVS datapath port type dpdk

  • Add ability to set MTU for dpdk representor potr type

  • Add ability to plug vf with VIFPortProfileOVSRepresentor vif profile for VIFVHostUser

  • Add/Update Unit and Functional tests


  • This blueprint is a prerequisite to update code in Neutron to support LinkVirtualization SmartNICs. This is in-line with support of other SmartNICs. Links to changes of all four components are given in the Work Items section.


Code changes will require additional testing coverage: * New unit tests will be implented or updated existing. * New functional tests will be implemented. * Napatech will provide third party ci for testing on the NT hardware.

Documentation Impact

We are not introducing any new VNIC type, so there should be no impact on documentation.




Release Name


2023.2 Bobcat