Chapter 17. Tenant networking with IPv6

17.1. Overview of tenant networking

This chapter contains information about implementing IPv6 subnets in a Red Hat OpenStack Platform (RHOSP) tenant network. In addition to tenant networking, with RHOSP director, you can configure IPv6-native deployments for the overcloud nodes.

RHOSP supports IPv6 in tenant networks. IPv6 subnets are created within existing tenant networks, and support a number of address assignment modes: Stateless Address Autoconfiguration (SLAAC), Stateful DHCPv6, and Stateless DHCPv6.

17.2. IPv6 subnet options

Create IPv6 subnets using the openstack subnet create command. You can also specify the address mode and the Router Advertisement mode. Use the following list to understand the possible combinations of options that you can include with the openstack subnet create command.

RA ModeAddress ModeResult

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 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.

17.3. Create an IPv6 subnet using Stateful DHCPv6

Complete the steps in this procedure to create an IPv6 subnet in a tenant network using some of the options in section 17.1. First, gather the necessary tenant and network information, then include this information in the openstack subnet create command.

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.

  1. Retrieve the tenant 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 |
    +----------------------------------+----------+
  2. Retrieve a list of all networks present in OpenStack Networking (neutron), and note the name of the network that 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 |                                                             |
    +--------------------------------------+------------------+-------------------------------------------------------------+
  3. Include the tenant ID and network name in the openstack subnet create command:

    # 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                             |
    +-------------------+--------------------------------------------------------------+
  4. 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        |
    +--------------------------------------+------------------+-------------------------------------------------------------+

    As a result of this configuration, instances that the QA tenant 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 |
    +--------------------------------------+------------+--------+------------+-------------+-------------------------------------+