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 PXE drivers operate in such a way that they are able to utilize
both IPv4 and IPv6 addresses based upon the deployment’s operating state and
configuration. Internally, the drivers attempt to prepare configuration options for both formats, which allows ports which are IPv6 only to automatically
receive boot parameters. As a result of this, it is critical that the
DEFAULT.my_ipv6 configuration parameter is set to the conductor’s
IPv6 address. This option is unique per conductor, and due to the nature
of automatic address assignment, it cannot be “guessed” by the software.
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.
