Smart NIC Networking!/story/2003346

This spec describes proposed changes to Ironic to enable a generic, vendor-agnostic, baremetal networking service running on smart NICs, enabling baremetal networking with feature parity to the virtualization use-case.

Problem description

While Ironic today supports Neutron provisioned network connectivity for baremetal servers through an ML2 mechanism driver, the existing support is based largely on configuration of TORs through vendor-specific mechanism drivers, with limited capabilities.

Proposed change

There is a wide range of smart/intelligent NICs emerging on the market. These NICs generally incorporate one or more general purpose CPU cores along with data-plane packet processing acceleration, and can efficiently run virtual switches such as OVS, while maintaining the existing interfaces to the SDN layer.

The proposal is to extend Ironic to enable use of smart NICs to implement generic networking services for Bare Metal servers. The goal is to enable running the standard Neutron Open vSwitch L2 agent, providing a generic, vendor-agnostic bare metal networking service with feature parity compared to the virtualization use-case. The Neutron Open vSwitch L2 agent manages the OVS bridges on the smart NIC.

In this proposal, we address two use-cases:

  1. Neutron OVS L2 agent runs locally on the smart NIC.

    This use case requires a smart NIC capable or running openstack control services such as the Neutron OVS L2 agent. This use case strives to view the smart NIC as an isolated hypervisor for the baremetal node, with the smart NIC providing the services to the bare metal image running on the host (as a hypervisor would provide services to a VM). While this spec initially targets Neutron OVS L2 agent, the same implementation would naturally and easily be extended to any other ML2 plugin as well as to additional agents/services (for example exposing emulated NVMe storage devices back-ended by a storage initiator on the smart NIC).

  2. Neutron OVS L2 agent(s) run remotely and manages the OVS bridges for all the baremetal smart NICs.

The enhancements for Neutron OVS L2 agent captured in [1], [2] and [3].

  • Set the smart NIC configuration

    smart NIC configuration includes the following:

    1. extend the ironic port with is_smartnic field. (default to False)

    2. smart NIC hostname - the hostname of server/smart NIC where the Neutron OVS agent is running. (required)

    3. smart NIC port id - the port name that needs to be plugged to the integration bridge. B in the diagram below (required)

    4. smart NIC SSH public key - ssh public key of the smart NIC (required only for remote)

    5. smart NIC OVSDB SSL certificate - OVSDB SSL of the OVS in smart NIC (required only for remote)

    The OVS ML2 mechanism driver will determine if the Neutron OVS Agent runs locally or remotely based on smart NIC configuration passed from ironic. The config attribute will be stored in the local_link_information of the baremetal port.

    In the scope of this spec the smart NIC config will be set manually by the admin.

  • Deployment Interfaces

    Extending the ramdisk, direct, iscsi and ansible to support the smart nic use-cases.

    The Deployment Interfaces call network interface methods such as: add_provisioning_network, remove_provisioning_network, configure_tenant_networks, unconfigure_tenant_networks, add_cleaning_network and remove_cleaning_network.

    These network methods are currently ordinarily called when the baremetal is powered down, ensuring proper network configuration on the TOR before booting the bare metal.

    smart NICs share the power state with the baremetal, requiring the baremetal to be powered up before configuring the network. This leads to a potential race where the baremetal boots and access the network prior to the network being properly configured on the OVS within the smart NIC.

    To ensure proper network configuration prior to baremetal boot, the deployment interfaces will intermittently boot the baremetal into the BIOS shell, providing a state where the ovs on the smart NIC may be configured properly before rebooting the bare metal into the actual guest image or ramdisk. The ovs on the smart NIC will get programmed after we verify that the neutron ovs agent is alive.

    The following code for configure/unconfigure network:

        old_power_state = task.driver.power.get_power_state(task)
        if old_power_state == states.POWER_OFF:
            # set next boot to BIOS to halt the baremetal boot
            manager_utils.node_set_boot_device(task, boot_devices.BIOS,
            manager_utils.node_power_action(task, states.POWER_ON)
    # ...
    # call method(s)
    # ...
        manager_utils.node_power_action(task, old_power_state)

    The following methods in the deployment interface are calling to one or more configure/unconfigure networks and should be updated with the logic above.

    • iscsi Deploy Interface

      • iscsi_deploy::prepare

      • iscsi_deploy::deploy

      • iscsi_deploy::tear_down

    • ansible Deploy Interface

      • ansible/deploy::reboot_and_finish_deploy

      • ansible/deploy::prepare

      • ansible/deploy::tear_down

      • ansible/deploy::prepare_cleaning

      • ansible/deploy::tear_down_cleaning

    • direct Interface

      • agent::prepare

      • agent::tear_down

      • agent::deploy

      • agent::rescue

      • agent::unrescue

      • agent_base_vendor::reboot_and_finish_deploy

      • agent_base_vendor::_finalize_rescue

    • RAM Disk Interface

      • pxe::deploy

    • Common cleaning methods

      • deploy_utils::prepare_inband_cleaning

      • deploy_utils::tear_down_inband_clean

  • Network Interface

    Extend the base network_interface with need_power_on - return true if any ironic port attached to the node is a smart nic

    Extend the ironic.common.neutron add_ports_to_network/ remove_ports_from_network methods for the smart NIC case:

    • on add_ports_to_network and has smartNIC do the following:

      • check neutron agent alive - verify that neutron agent is alive

      • create neutron port

      • check neutron port active - verify that neutron port is in active state

    • on remove_ports_from_network and has smartNIC do the following:

      • check neutron agent alive - verify that neutron agent is alive

      • delete neutron port

      • check neutron port is removed

  • Neutron ml2 OVS changes:

    • Introduce a new vnic_type for smart-nic.

    • Update the Neutron ml2 OVS to bind smart-nic vnic_type with binding:profile smart NIC config.

  • Neutron OVS agent changes:

Example of smart NIC model:

|      baremetal      |
| +-----------------+ |
| |  OS Server    | | |
| |               | | |
| |      +A       | | |
| +------|--------+ | |
|        |          | |
| +------|--------+ | |
| |  OS SmartNIC  | | |
| |    +-+B-+     | | |
| |    |OVS |     | | |
| |    +-+C-+     | | |
| +------|--------+ | |

A - port on the baremetal host.
B - port that represents the baremetal port in the smart NIC.
C - port that represents to the physical port in the smart NIC.

Add/Remove Port B to the OVS br-int with external-ids

In our case we will use the neutron OVS agent to plug the port on update
port event with the following external-ids: iface-id,iface-status, attached-mac
and node-uuid


  • Delay the Neutron port binding (port binding means setting all the OVSDB/Openflows config on the SmartNIC) to be performed by Neutron later (once the bare metal is powered up). The problem with this approach is that we have no guarantee of if/when the rules will be programmed, and thus may inadvertently boot the baremetal while the smart NIC is still programmed on the old network.

Data model impact

A new is_smartnic boolean field will be added to Port object.

State Machine Impact


REST API impact

The port REST API will be modified to support the new is_smartnic field. The field will be readable by users with the baremetal observer role and writable by users with the baremetal admin role.

Updates to the is_smartnic field of ports will be restricted in the same way as for other connectivity related fields (link local connection, etc.) - they will be restricted to nodes in the enroll, inspecting and manageable states.

Client (CLI) impact

“ironic” CLI


“openstack baremetal” CLI

The openstack baremetal CLI will be updated to support getting and setting the is_smartnic field on ports.

RPC API impact


Driver API impact


Nova driver impact


Ramdisk impact


Security impact

  • Smart NIC Isolation

Both use cases run infrastructure functionality on the smart NIC, with the first use case also running control plane functionality.

This requires proper isolation between the untrusted bare metal host and the smart NIC, preventing any/all direct or indirect access, both through the network interface exposed to the host and through side channels such as the platform BMC.

Such isolation is implemented by the smart NIC device and/or the hardware platform vendor. There are multiple approaches for such isolation, ranging from completely physical disconnection of the smart NIC from the platform BMC to a platform with a trusted BMC wherein the BMC considers the baremetal host an untrusted entity and restricts its capabilities/access to the platform.

In the absence of such isolation, the untrusted baremetal tenant may be able to gain access to the provisioning network, and in the second may be able to compromise the control plane.

Proper isolation is dependent on the platform hardware/firmware, and cannot be directly enforced/guaranteed by ironic. Users of smart NIC use case should be made well aware of this via explicit documentation, and should be guided to verify the proper isolation exists on their platform when enabling such use cases.

  • Security Groups

This will allow to use Neutron OVS agent pipeline. One of the features in the pipeline is security groups which will enhance the security model when using baremetal in a cloud.

  • Security credentials

The node running the Neutron OVS agent (smart NIC or remote, according to use case) should be configured with the message bus credentials for the Neutron server.

In addition, for the second use case, the SSH public key and OVSDB SSL certificate should be configured for the smart NIC port.

Other end user impact

  • Baremetal admin needs to update the SmartNIC config manually.

Scalability impact


Performance Impact


Other deployer impact


Developer impact




Primary assignee:

hamdyk -

Work Items

  • Update the Neutron network interface to populate the Smart NIC config from the ironic port to the Neutron port binding:profile attribute.

  • Update the network_interface and common.neutron as described above

  • Update deployment interfaces as described above

  • Documentation updates.


None, but the Neutron specs [1], [2] and [3] depend on this spec.


  • Mellanox CI Jobs testing with Bluefield SmartNIC

Upgrades and Backwards Compatibility


Documentation Impact

  • Update the multitenancy.rst with setting the SmartNIC config

  • Document the security implications/guidelines under admin/security.rst