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Taikun OCP Guide

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Multi-tenancy in the Bare Metal service


It is possible to use dedicated tenant networks for provisioned
nodes, which extends the current Bare Metal service capabilities of
providing flat networks. This works in conjunction with the Networking
service to allow provisioning of nodes in a separate provisioning
network. The result of this is that multiple tenants can use nodes in an
isolated fashion. However, this configuration does not support trunk
ports belonging to multiple networks.


Network interfaces

Network interface is one of the driver interfaces that manages
network switching for nodes. There are 3 network interfaces available in
the Bare Metal service:

  • noop interface is used for standalone deployments, and
    does not perform any network switching;
  • flat interface places all nodes into a single provider
    network that is pre-configured on the Networking service and physical
    equipment. Nodes remain physically connected to this network during
    their entire life cycle.
  • neutron interface provides tenant-defined networking
    through the Networking service, separating tenant networks from each
    other and from the provisioning and cleaning provider networks. Nodes
    will move between these networks during their life cycle. This interface
    requires Networking service support for the switches attached to the
    baremetal servers so they can be programmed.

The Bare Metal service allows local_link_connection
information to be associated with Bare Metal ports. This information is
provided to the Networking service’s ML2 driver when a Virtual Interface
(VIF) is attached. The ML2 driver uses the information to plug the
specified port to the tenant network.

local_link_connection fields
Field Description
switch_id Required. Identifies a switch and can be a MAC address or an
OpenFlow-based datapath_id.
port_id Required. Port ID on the switch/Smart NIC, for example, Gig0/1,
switch_info Optional. Used to distinguish different switch models or other
vendor-specific identifier. Some ML2 plugins may require this
hostname Required in case of a Smart NIC port. Hostname of Smart NIC


This isn’t applicable to Infiniband ports because the network
topology is discoverable by the Infiniband Subnet Manager. If specified,
local_link_connection information will be ignored. If port is Smart NIC
port then:

  1. port_id is the representor port name on the Smart
  2. switch_id is not mandatory.

Physical networks

A Bare Metal port may be associated with a physical network using its
physical_network field. The Bare Metal service uses this
information when mapping between virtual ports in the Networking service
and physical ports and port groups in the Bare Metal service. A port’s
physical network field is optional, and if not set then any virtual port
may be mapped to that port, provided that no free Bare Metal port with a
suitable physical network assignment exists.

The physical network of a port group is defined by the physical
network of its constituent ports. The Bare Metal service ensures that
all ports in a port group have the same value in their physical network

When attaching a virtual interface (VIF) to a node, the following
ordered criteria are used to select a suitable unattached port or port

  • Require ports or port groups to not have a physical network or to
    have a physical network that matches one of the VIF’s allowed physical
  • Prefer ports and port groups that have a physical network to ports
    and port groups that do not have a physical network.
  • Prefer port groups to ports. Prefer ports with PXE enabled.

Configuring the Bare Metal

See the configure-tenant-networks section in the installation
guide for the Bare Metal service.

Configuring nodes

  1. Ensure that your python-ironicclient version and requested API
    version are sufficient for your requirements.

    • Multi-tenancy support was added in API version 1.20, and is
      supported by python-ironicclient version 1.5.0 or higher.
    • Physical network support for ironic ports was added in API version
      1.34, and is supported by python-ironicclient version 1.15.0 or
    • Smart NIC support for ironic ports was added in API version 1.53,
      and is supported by python-ironicclient version 2.7.0 or higher.

    The following examples assume you are using python-ironicclient
    version 2.7.0 or higher.

    Export the following variable:

    export OS_BAREMETAL_API_VERSION=<API version>
  2. The node’s network_interface field should be set to
    a valid network interface. Valid interfaces are listed in the
    [DEFAULT]/enabled_network_interfaces configuration option
    in the ironic-conductor’s configuration file. Set it to
    neutron to use the Networking service’s ML2 driver:

    baremetal node create --network-interface neutron --driver ipmi


    If the [DEFAULT]/default_network_interface configuration
    option is set, the --network-interface option does not need
    to be specified when creating the node.

  3. To update an existing node’s network interface to
    neutron, use the following commands:

    baremetal node set $NODE_UUID_OR_NAME \
        --network-interface neutron
  4. Create a port as follows:

    baremetal port create $HW_MAC_ADDRESS --node $NODE_UUID \
        --local-link-connection switch_id=$SWITCH_MAC_ADDRESS \
        --local-link-connection switch_info=$SWITCH_HOSTNAME \
        --local-link-connection port_id=$SWITCH_PORT \
        --pxe-enabled true \
        --physical-network physnet1

    An Infiniband port requires client ID, while local link connection
    information will be populated by Infiniband Subnet Manager. The client
    ID consists of <12-byte vendor prefix>:<8 byte port GUID>.
    There is no standard process for deriving the port’s MAC address
    ($HW_MAC_ADDRESS); it is vendor specific. For example, Mellanox ConnectX
    Family Devices prefix is ff:00:00:00:00:00:02:00:00:02:c9:00. If port
    GUID was f4:52:14:03:00:38:39:81 the client ID would be
    ff:00:00:00:00:00:02:00:00:02:c9:00:f4:52:14:03:00:38:39:81. Mellanox
    ConnectX Family Device’s HW_MAC_ADDRESS consists of 6 bytes; the port
    GUID’s lower 3 and higher 3 bytes. In this example it would be
    f4:52:14:38:39:81. Putting it all together, create an Infiniband port as

    baremetal port create $HW_MAC_ADDRESS --node $NODE_UUID \
        --pxe-enabled true \
        --extra client-id=$CLIENT_ID \
        --physical-network physnet1
  5. Create a Smart NIC port as follows:

    baremetal port create $HW_MAC_ADDRESS --node $NODE_UUID \
        --local-link-connection hostname=$HOSTNAME \
        --local-link-connection port_id=$REP_NAME \
        --pxe-enabled true \
        --physical-network physnet1 \

    A Smart NIC port requires hostname which is the hostname
    of the Smart NIC, and port_id which is the representor port
    name within the Smart NIC.

  6. Check the port configuration:

    baremetal port show $PORT_UUID

After these steps, the provisioning of the created node will happen
in the provisioning network, and then the node will be moved to the
tenant network that was requested.

Configuring the Networking

In addition to configuring the Bare Metal service some additional
configuration of the Networking service is required to ensure ports for
bare metal servers are correctly programmed. This configuration will be
determined by the Bare Metal service network interfaces you have enabled
and which top of rack switches you have in your environment.

flat network interface

In order for Networking service ports to correctly operate with the
Bare Metal service flat network interface the
baremetal ML2 mechanism driver from networking-baremetal
needs to be loaded into the Networking service configuration. This
driver understands that the switch should be already configured by the
admin, and will mark the networking service ports as successfully bound
as nothing else needs to be done.

  1. Install the networking-baremetal library

    $ pip install networking-baremetal
  2. Enable the baremetal driver in the Networking
    service ML2 configuration file

    mechanism_drivers = ovs,baremetal

neutron network

The neutron network interface allows the Networking
service to program the physical top of rack switches for the bare metal
servers. To do this an ML2 mechanism driver which supports the
baremetal VNIC type for the make and model of top of rack
switch in the environment must be installed and enabled.

This is a list of known top of rack ML2 mechanism drivers which work
with the neutron network interface:

Cisco Nexus 9000 series

To install and configure this ML2 mechanism driver see Nexus
Mechanism Driver Installation Guide


networking-fujitsu ML2 driver supports this switch. The
documentation is available here.

Networking Generic Switch

This is an ML2 mechanism driver built for testing against virtual
bare metal environments and some switches that are not covered by
hardware specific ML2 mechanism drivers. More information is available
in the project’s README.