IPv6 Networking for the Overcloud

IPv6 is the latest version of the Internet Protocol standard. Internet Engineering Task Force (IETF) developed IPv6 as a means to combat the exhaustion of IP address from the current common IPv4 standard. IPv6 has various differences from IPv4 including:

IPv6 uses 128 bits (represented with 4 hexadecimals using groups of 16 bits) to define addresses while IPv4 uses only 32 bits (represented with decimal digits using groups of 8 bits). For example, a representation of an IPv4 address (192.168.0.1) looks like this:

For an IPv6 address (2001:db8:88ec:9fb3::1), the representation looks like this:

You can also represent IPv6 addresses without leading zeros in each bit group and omit a set of zero bit groups once for each IP address. In this example, you can represent the 0db8 bit grouping as just db8 and omit the three sets of 0000 bit groups, which shortens the representation from 2001:0db8:88ec:9fb3:0000:0000:0000:0001 to 2001:db8:88ec:9fb3::1. For more information, see "RFC 5952: A Recommendation for IPv6 Address Text Representation"

Subnetting in IPv6

Similar to IPv4, an IPv6 address uses a bit mask to define the address prefix as its network. For example, if you include a /64 bit mask to the sample IP address 2001:db8:88ec:9fb3::1/64, the bit mask acts as a prefix that defines the first 64 bits (2001:db8:88ec:9fb3) as the network. The remaining bits (0000:0000:0000:0001) define the host.

IPv6 also uses some special address types:

Red Hat OpenStack Platform (RHOSP) director maps OpenStack services to isolated networks. These networks include:

For more information about these network traffic types, see the Director Installation and Usage guide.

Director also provides methods to use IPv6 communication for these networks. This means the required OpenStack services, databases, and other related services use IPv6 addresses to communicate. This also applies to environments that use a high availability solution involving multiple Controller nodes. This helps organizations integrate RHOSP with their IPv6 infrastructure.

Use the following table as a guide for which RHOSP networks support IPv6:

This guide uses a scenario similar to the advanced overcloud scenario. The main difference is the omission of the Ceph Storage nodes.

For more information about this scenario, see the Director Installation and Usage guide.

The undercloud requires access to the overcloud Public API, which is on the External network. To accomplish this, the undercloud host requires an IPv6 address on the interface that connects to the External network.

Native VLAN or dedicated interface

If the undercloud uses a native VLAN or a dedicated interface attached to the External network, use the ip command to add an IPv6 address to the interface. In this example, the dedicated interface is eth0:

$ sudo ip link set dev eth0 up; sudo ip addr add 2001:db8::1/64 dev eth0

Trunked VLAN interface

If the undercloud uses a trunked VLAN on the same interface as the control plane bridge (br-ctlplane) to access the External network, create a new VLAN interface, attach it to the control plane, and add an IPv6 address to the VLAN. In this example, the External network VLAN ID is 100:

$ sudo ovs-vsctl add-port br-ctlplane vlan100 tag=100 -- set interface vlan100 type=internal
$ sudo ip l set dev vlan100 up; sudo ip addr add 2001:db8::1/64 dev vlan100

Confirming the IPv6 address

Confirm the addition of the IPv6 address with the ip command:

$ ip addr

The IPv6 address appears on the chosen interface.

Setting a persistent IPv6 address

To make the IPv6 address permanent, modify or create the appropriate interface file in /etc/sysconfig/network-scripts/. In this example, include the following lines in either ifcfg-eth0 or ifcfg-vlan100:

IPV6INIT=yes
IPV6ADDR=2001:db8::1/64

For more information, see How do I configure a network interface for IPv6? on the Red Hat Customer Portal.

A node definition template (instackenv.json) is a JSON format file that contains the hardware and power management details for registering nodes. For example:

{
    "nodes":[
        {
            "mac":[
                "bb:bb:bb:bb:bb:bb"
            ],
            "cpu":"4",
            "memory":"6144",
            "disk":"40",
            "arch":"x86_64",
            "pm_type":"ipmi",
            "pm_user":"admin",
            "pm_password":"p@55w0rd!",
            "pm_addr":"192.0.2.205"
        },
        {
            "mac":[
                "cc:cc:cc:cc:cc:cc"
            ],
            "cpu":"4",
            "memory":"6144",
            "disk":"40",
            "arch":"x86_64",
            "pm_type":"ipmi",
            "pm_user":"admin",
            "pm_password":"p@55w0rd!",
            "pm_addr":"192.0.2.206"
        },
        {
            "mac":[
                "dd:dd:dd:dd:dd:dd"
            ],
            "cpu":"4",
            "memory":"6144",
            "disk":"40",
            "arch":"x86_64",
            "pm_type":"ipmi",
            "pm_user":"admin",
            "pm_password":"p@55w0rd!",
            "pm_addr":"192.0.2.207"
        },
        {
            "mac":[
                "ee:ee:ee:ee:ee:ee"
            ],
            "cpu":"4",
            "memory":"6144",
            "disk":"40",
            "arch":"x86_64",
            "pm_type":"ipmi",
            "pm_user":"admin",
            "pm_password":"p@55w0rd!",
            "pm_addr":"192.0.2.208"
        }
        {
            "mac":[
                "ff:ff:ff:ff:ff:ff"
            ],
            "cpu":"4",
            "memory":"6144",
            "disk":"40",
            "arch":"x86_64",
            "pm_type":"ipmi",
            "pm_user":"admin",
            "pm_password":"p@55w0rd!",
            "pm_addr":"192.0.2.209"
        }
        {
            "mac":[
                "gg:gg:gg:gg:gg:gg"
            ],
            "cpu":"4",
            "memory":"6144",
            "disk":"40",
            "arch":"x86_64",
            "pm_type":"ipmi",
            "pm_user":"admin",
            "pm_password":"p@55w0rd!",
            "pm_addr":"192.0.2.210"
        }
    ]
}

After you register and inspect the hardware of your nodes, tag each node into a specific profile. These profile tags map your nodes to flavors, and in turn the flavors are assigned to a deployment role.

This section examines the network configuration for the overcloud. This includes isolating the OpenStack services to use specific network traffic and configuring the overcloud with IPv6 options.

parameter_defaults:
  # Enable IPv6 for Ceph.
  CephIPv6: True
  # Enable IPv6 for Corosync. This is required when Corosync is using an IPv6 IP in the cluster.
  CorosyncIPv6: True
  # Enable IPv6 for MongoDB. This is required when MongoDB is using an IPv6 IP.
  MongoDbIPv6: True
  # Enable various IPv6 features in Nova.
  NovaIPv6: True
  # Enable IPv6 environment for RabbitMQ.
  RabbitIPv6: True
  # Enable IPv6 environment for Memcached.
  MemcachedIPv6: True
  # Enable IPv6 environment for MySQL.
  MysqlIPv6: True
  # Enable IPv6 environment for Manila
  ManilaIPv6: True
  # Enable IPv6 environment for Redis.
  RedisIPv6: True

To deploy an overcloud that uses IPv6 networking, you must include additional arguments in the deployment command.

$ openstack overcloud deploy --templates \
  -e /usr/share/openstack-tripleo-heat-templates/environments/network-isolation.yaml \
  -e /usr/share/openstack-tripleo-heat-templates/environments/net-single-nic-with-vlans.yaml \
  -e /home/stack/templates/network-environment.yaml \
  --ntp-server pool.ntp.org \
  [ADDITIONAL OPTIONS]

The above command uses the following options:

The overcloud creation process begins and director provisions the overcloud nodes. This process takes some time to complete. To view the status of the overcloud creation, open a separate terminal as the stack user and run:

$ source ~/stackrc
$ heat stack-list --show-nested

$ source ~/overcloudrc

This loads the necessary environment variables to interact with your overcloud from the director host CLI. To return to interacting with the director host, run the following command:

$ source ~/stackrc

The overcloud requires an IPv6-based Project network for instances. Source the overcloudrc file and create an initial Project network in neutron.

After you configure the node interfaces to use the External network, you must create this network on the overcloud to enable network access.