Chapter 14. Project networking with IPv6
14.1. IPv6 subnet options
When you create IPv6 subnets in a Red Hat OpenStack Platform (RHOSP) project network you can specify address mode and Router Advertisement mode to obtain a particular result as described in the following table.
RHOSP does not support IPv6 prefix delegation from an external entity in ML2/OVN deployments. You must obtain the the Global Unicast Address prefix from your external prefix delegation router and set it by using the subnet-range argument during creation of a IPv6 subnet.
For example:
openstack subnet create --subnet-range 2002:c000:200::64 --no-dhcp --gateway 2002:c000:2fe:: --dns-nameserver 2002:c000:2fe:: --network provider provider-subnet-2002:c000:200::
| RA Mode | Address Mode | Result |
|---|---|---|
| ipv6_ra_mode=not set | ipv6-address-mode=slaac | The instance receives an IPv6 address from the external router (not managed by OpenStack Networking) using Stateless Address Autoconfiguration (SLAAC). Note OpenStack Networking supports only EUI-64 IPv6 address assignment for SLAAC. This allows for simplified IPv6 networking, as hosts self-assign addresses based on the base 64-bits plus the MAC address. You cannot create subnets with a different netmask and address_assign_type of SLAAC. |
| ipv6_ra_mode=not set | ipv6-address-mode=dhcpv6-stateful | The instance receives an IPv6 address and optional information from OpenStack Networking (dnsmasq) using DHCPv6 stateful. |
| ipv6_ra_mode=not set | ipv6-address-mode=dhcpv6-stateless | The instance receives an IPv6 address from the external router using SLAAC, and optional information from OpenStack Networking (dnsmasq) using DHCPv6 stateless. |
| ipv6_ra_mode=slaac | ipv6-address-mode=not-set | The instance uses SLAAC to receive an IPv6 address from OpenStack Networking (radvd). |
| ipv6_ra_mode=dhcpv6-stateful | ipv6-address-mode=not-set | The instance receives an IPv6 address and optional information from an external DHCPv6 server using DHCPv6 stateful. |
| ipv6_ra_mode=dhcpv6-stateless | ipv6-address-mode=not-set | The instance receives an IPv6 address from OpenStack Networking (radvd) using SLAAC, and optional information from an external DHCPv6 server using DHCPv6 stateless. |
| ipv6_ra_mode=slaac | ipv6-address-mode=slaac | The instance receives an IPv6 address from OpenStack Networking (radvd) using SLAAC. |
| ipv6_ra_mode=dhcpv6-stateful | ipv6-address-mode=dhcpv6-stateful | The instance receives an IPv6 address from OpenStack Networking (dnsmasq) using DHCPv6 stateful, and optional information from OpenStack Networking (dnsmasq) using DHCPv6 stateful. |
| ipv6_ra_mode=dhcpv6-stateless | ipv6-address-mode=dhcpv6-stateless | The instance receives an IPv6 address from OpenStack Networking (radvd) using SLAAC, and optional information from OpenStack Networking (dnsmasq) using DHCPv6 stateless. |
14.2. Create an IPv6 subnet using Stateful DHCPv6
You can create an IPv6 subnet in a Red Hat OpenStack (RHOSP) project network.
For example, you can create an IPv6 subnet using Stateful DHCPv6 in network named database-servers in a project named QA.
Procedure
Retrieve the project ID of the Project where you want to create the IPv6 subnet. These values are unique between OpenStack deployments, so your values differ from the values in this example.
# openstack project list +----------------------------------+----------+ | ID | Name | +----------------------------------+----------+ | 25837c567ed5458fbb441d39862e1399 | QA | | f59f631a77264a8eb0defc898cb836af | admin | | 4e2e1951e70643b5af7ed52f3ff36539 | demo | | 8561dff8310e4cd8be4b6fd03dc8acf5 | services | +----------------------------------+----------+
Retrieve a list of all networks present in OpenStack Networking (neutron), and note the name of the network where you want to host the IPv6 subnet:
# openstack network list +--------------------------------------+------------------+-------------------------------------------------------------+ | id | name | subnets | +--------------------------------------+------------------+-------------------------------------------------------------+ | 8357062a-0dc2-4146-8a7f-d2575165e363 | private | c17f74c4-db41-4538-af40-48670069af70 10.0.0.0/24 | | 31d61f7d-287e-4ada-ac29-ed7017a54542 | public | 303ced03-6019-4e79-a21c-1942a460b920 172.24.4.224/28 | | 6aff6826-4278-4a35-b74d-b0ca0cbba340 | database-servers | | +--------------------------------------+------------------+-------------------------------------------------------------+
Include the project ID, network name, and ipv6 address mode in the
openstack subnet createcommand:# openstack subnet create --ip-version 6 --ipv6-address-mode dhcpv6-stateful --project 25837c567ed5458fbb441d39862e1399 --network database-servers --subnet-range fdf8:f53b:82e4::53/125 subnet_name Created a new subnet: +-------------------+--------------------------------------------------------------+ | Field | Value | +-------------------+--------------------------------------------------------------+ | allocation_pools | {"start": "fdf8:f53b:82e4::52", "end": "fdf8:f53b:82e4::56"} | | cidr | fdf8:f53b:82e4::53/125 | | dns_nameservers | | | enable_dhcp | True | | gateway_ip | fdf8:f53b:82e4::51 | | host_routes | | | id | cdfc3398-997b-46eb-9db1-ebbd88f7de05 | | ip_version | 6 | | ipv6_address_mode | dhcpv6-stateful | | ipv6_ra_mode | | | name | | | network_id | 6aff6826-4278-4a35-b74d-b0ca0cbba340 | | tenant_id | 25837c567ed5458fbb441d39862e1399 | +-------------------+--------------------------------------------------------------+
Validation steps
Validate this configuration by reviewing the network list. Note that the entry for database-servers now reflects the newly created IPv6 subnet:
# openstack network list +--------------------------------------+------------------+-------------------------------------------------------------+ | id | name | subnets | +--------------------------------------+------------------+-------------------------------------------------------------+ | 6aff6826-4278-4a35-b74d-b0ca0cbba340 | database-servers | cdfc3398-997b-46eb-9db1-ebbd88f7de05 fdf8:f53b:82e4::50/125 | | 8357062a-0dc2-4146-8a7f-d2575165e363 | private | c17f74c4-db41-4538-af40-48670069af70 10.0.0.0/24 | | 31d61f7d-287e-4ada-ac29-ed7017a54542 | public | 303ced03-6019-4e79-a21c-1942a460b920 172.24.4.224/28 | +--------------------------------------+------------------+-------------------------------------------------------------+
Result
As a result of this configuration, instances that the QA project creates can receive a DHCP IPv6 address when added to the database-servers subnet:
# openstack server list +--------------------------------------+------------+--------+------------+-------------+-------------------------------------+ | ID | Name | Status | Task State | Power State | Networks | +--------------------------------------+------------+--------+------------+-------------+-------------------------------------+ | fad04b7a-75b5-4f96-aed9-b40654b56e03 | corp-vm-01 | ACTIVE | - | Running | database-servers=fdf8:f53b:82e4::52 | +--------------------------------------+------------+--------+------------+-------------+-------------------------------------+
Additional resources
To find the Router Advertisement mode and address mode combinations to achieve a particular result in an IPv6 subnet, see IPv6 subnet options in the Networking Guide.
