Configuring services for bare metal provisioning using IPv6

Use of IPv6 addressing for baremetal provisioning requires additional configuration. This page covers the IPv6 specifics only. Please refer to Configure tenant networks and Configure the Networking service for bare metal provisioning for general networking configuration.

Configure ironic PXE driver for provisioning using IPv6 addressing

The ironic PXE driver operates in either IPv4 or IPv6 mode (IPv4 is the default). To enable IPv6 mode, set the [pxe]/ip_version option in the Bare Metal Service’s configuration file (/etc/ironic/ironic.conf) to 6.

Note

Support for dual mode IPv4 and IPv6 operations is planned for a future version of ironic.

Provisioning with IPv6 stateless addressing

When using stateless addressing DHCPv6 does not provide addresses to the client. DHCPv6 however provides other configuration via DHCPv6 options such as the bootfile-url and bootfile-parameters.

Once the PXE driver is set to operate in IPv6 mode no further configuration is required in the Baremetal Service.

Creating networks and subnets in the Networking Service

When creating the Baremetal Service network(s) and subnet(s) in the Networking Service’s, subnets should have ipv6-address-mode set to dhcpv6-stateless and ip-version set to 6. Depending on whether a router in the Networking Service is providing RA’s (Router Advertisements) or not, the ipv6-ra-mode for the subnet(s) should either be set to dhcpv6-stateless or be left unset.

Note

If ipv6-ra-mode is left unset, an external router on the network is expected to provide RA’s with the appropriate flags set for automatic addressing and other configuration.

Provisioning with IPv6 stateful addressing

When using stateful addressing DHCPv6 is providing both addresses and other configuration via DHCPv6 options such as the bootfile-url and bootfile- parameters.

The “identity-association” (IA) construct used by DHCPv6 is challenging when booting over the network. Firmware, and ramdisks typically end up using different DUID/IAID combinations and it is not always possible for one chain- booting stage to release its address before giving control to the next step. In case the DHCPv6 server is configured with static reservations only the result is that booting will fail because the DHCPv6 server has no addresses available. To get past this issue either configure the DHCPv6 server with multiple address reservations for each host, or use a dynamic range.

Note

Support for multiple address reservations requires dnsmasq version 2.81 or later. Some distributions may backport this feature to earlier dnsmasq version as part of the packaging, check the distributions release notes.

If a different (not dnsmasq) DHCPv6 server backend is used with the Networking service, use of multiple address reservations might not work.

Using the flat network interface

Due to the “identity-association” challenges with DHCPv6 provisioning using the flat network interface is not recommended. When ironic operates with the flat network interface the server instance port is used for provisioning and other operations. Ironic will not use multiple address reservations in this scenario. Because of this it will not work in most cases.

Using the neutron network interface

When using the neutron network interface the Baremetal Service will allocate multiple IPv6 addresses (4 addresses per port by default) on the service networks used for provisioning, cleaning, rescue and introspection. The number of addresses allocated can be controlled via the [neutron]/dhcpv6_stateful_address_count option in the Bare Metal Service’s configuration file (/etc/ironic/ironic.conf). Using multiple address reservations ensures that the DHCPv6 server can lease addresses to each step.

To enable IPv6 provisioning on neutron flat provider networks with no switch management, the local_link_connection field of baremetal ports must be set to {'network_type': 'unmanaged'}. The following example shows how to set the local_link_connection for operation on unmanaged networks:

baremetal port set \
  --local-link-connection network_type=unmanaged <port-uuid>

The use of multiple IPv6 addresses must also be enabled in the Networking Service’s dhcp agent configuration (/etc/neutron/dhcp_agent.ini) by setting the option [DEFAULT]/dnsmasq_enable_addr6_list to True (default False in Ussuri release).

Note

Support for multiple IPv6 address reservations in the dnsmasq backend was added to the Networking Service Ussuri release. It was also backported to the stable Train release.

Creating networks and subnets in the Networking Service

When creating the ironic service network(s) and subnet(s) in the Networking Service, subnets should have ipv6-address-mode set to dhcpv6-stateful and ip-version set to 6. Depending on whether a router in the Networking Service is providing RA’s (Router Advertisements) or not, the ipv6-ra-mode for the subnet(s) should be set to either dhcpv6-stateful or be left unset.

Note

If ipv6-ra-mode is left unset, an external router on the network is expected to provide RA’s with the appropriate flags set for managed addressing and other configuration.