Baremetal provisioning guide for OVN

The purpose of this page is to describe how the baremetal provisioning can be configured with ML2/OVN.

Baremetal provisioning with ML2/OVN can be achieved using the OVN’s built-in DHCP server or Neutron’s DHCP agent.

How to configure it

Scheduling baremetal ports

The first thing to know is that when a port with VNIC baremetal is created, ML2/OVN will create an OVN port of the type external. These ports will be bound to nodes that have external connectivity and are responsible to responding to the ARP requests on behalf of the baremetal node.

For more information about external ports, its scheduling and troubleshoot please check the External Ports guide.

Metadata access

Different from ML2/OVS, ML2/OVN requires to have the ovn-metadata-agent running on the node that the virtual machines are running onto. Since baremetal requires an external port that will be bound to another node, as explained Scheduling baremetal ports section, it is required that the ovn-metadata-agent is also deployed on the nodes marked with the enable-chassis-as-gw option so it can serve metadata to the baremetal nodes booting off those external ports.

Using OVN built-in DHCP for PXE booting

This feature requires OVN running the version 23.06 or above for IPv4 and IPv6 support. If only IPv4 is needed, the OVN version 22.06 is the minimum required.

The version of OVN used for baremetal provisioning should include the following commits [[1]] [[2]].

And last, make sure that configuration option [ovn]/disable_ovn_dhcp_for_baremetal_ports is set to False (the default).

Using Neutron DHCP Agent for PXE booting

If using the OVN built-in DHCP server is not desirable, the operator will need to deploy Neutron’s DHCP agents on the controller nodes and also disable the OVN’s DHCP server for the baremetal ports by setting the [ovn]/disable_ovn_dhcp_for_baremetal_ports configuration option to True (defaults to False).