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Taikun OCP Guide

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Service subnets

Service subnets enable operators to define valid port types for each
subnet on a network without limiting networks to one subnet or manually
creating ports with a specific subnet ID. Using this feature, operators
can ensure that ports for instances and router interfaces, for example,
always use different subnets.

Operation

Define one or more service types for one or more subnets on a
particular network. Each service type must correspond to a valid device
owner within the port model in order for it to be used.

During IP allocation, the IPAM <config-ipam> driver returns an address
from a subnet with a service type matching the port device owner. If no
subnets match, or all matching subnets lack available IP addresses, the
IPAM driver attempts to use a subnet without any service types to
preserve compatibility. If all subnets on a network have a service type,
the IPAM driver cannot preserve compatibility. However, this feature
enables strict IP allocation from subnets with a matching device owner.
If multiple subnets contain the same service type, or a subnet without a
service type exists, the IPAM driver selects the first subnet with a
matching service type. For example, a floating IP agent gateway port
uses the following selection process:

  • network:floatingip_agent_gateway
  • None

Note

Ports with the device owner network:dhcp are exempt from
the above IPAM logic for subnets with dhcp_enabled set to
True. This preserves the existing automatic DHCP port
creation behaviour for DHCP-enabled subnets.

Creating or updating a port with a specific subnet skips this
selection process and explicitly uses the given subnet.

Usage

Note

Creating a subnet with a service type requires administrative
privileges.

Example 1 – Proof-of-concept

This following example is not typical of an actual deployment. It is
shown to allow users to experiment with configuring service subnets.

  1. Create a network.

    $ openstack network create demo-net1
    +---------------------------+--------------------------------------+
    | Field                     | Value                                |
    +---------------------------+--------------------------------------+
    | admin_state_up            | UP                                   |
    | availability_zone_hints   |                                      |
    | availability_zones        |                                      |
    | description               |                                      |
    | headers                   |                                      |
    | id                        | b5b729d8-31cc-4d2c-8284-72b3291fec02 |
    | ipv4_address_scope        | None                                 |
    | ipv6_address_scope        | None                                 |
    | mtu                       | 1450                                 |
    | name                      | demo-net1                            |
    | port_security_enabled     | True                                 |
    | project_id                | a3db43cd0f224242a847ab84d091217d     |
    | provider:network_type     | vxlan                                |
    | provider:physical_network | None                                 |
    | provider:segmentation_id  | 110                                  |
    | revision_number           | 1                                    |
    | router:external           | Internal                             |
    | shared                    | False                                |
    | status                    | ACTIVE                               |
    | subnets                   |                                      |
    | tags                      | []                                   |
    +---------------------------+--------------------------------------+
  2. Create a subnet on the network with one or more service types.
    For example, the compute:nova service type enables
    instances to use this subnet.

    $ openstack subnet create demo-subnet1 --subnet-range 192.0.2.0/24 \
      --service-type 'compute:nova' --network demo-net1
    +-------------------+--------------------------------------+
    | Field             | Value                                |
    +-------------------+--------------------------------------+
    | id                | 6e38b23f-0b27-4e3c-8e69-fd23a3df1935 |
    | ip_version        | 4                                    |
    | cidr              | 192.0.2.0/24                         |
    | name              | demo-subnet1                         |
    | network_id        | b5b729d8-31cc-4d2c-8284-72b3291fec02 |
    | revision_number   | 1                                    |
    | service_types     | ['compute:nova']                     |
    | tags              | []                                   |
    | tenant_id         | a8b3054cc1214f18b1186b291525650f     |
    +-------------------+--------------------------------------+
  3. Optionally, create another subnet on the network with a different
    service type. For example, the compute:foo arbitrary
    service type.

    $ openstack subnet create demo-subnet2 --subnet-range 198.51.100.0/24 \
      --service-type 'compute:foo' --network demo-net1
    +-------------------+--------------------------------------+
    | Field             | Value                                |
    +-------------------+--------------------------------------+
    | id                | ea139dcd-17a3-4f0a-8cca-dff8b4e03f8a |
    | ip_version        | 4                                    |
    | cidr              | 198.51.100.0/24                      |
    | name              | demo-subnet2                         |
    | network_id        | b5b729d8-31cc-4d2c-8284-72b3291fec02 |
    | revision_number   | 1                                    |
    | service_types     | ['compute:foo']                      |
    | tags              | []                                   |
    | tenant_id         | a8b3054cc1214f18b1186b291525650f     |
    +-------------------+--------------------------------------+
  4. Launch an instance using the network. For example, using the
    cirros image and m1.tiny flavor.

    $ openstack server create demo-instance1 --flavor m1.tiny \
      --image cirros --nic net-id=b5b729d8-31cc-4d2c-8284-72b3291fec02
    +--------------------------------------+-----------------------------------------------+
    | Field                                | Value                                         |
    +--------------------------------------+-----------------------------------------------+
    | OS-DCF:diskConfig                    | MANUAL                                        |
    | OS-EXT-AZ:availability_zone          |                                               |
    | OS-EXT-SRV-ATTR:host                 | None                                          |
    | OS-EXT-SRV-ATTR:hypervisor_hostname  | None                                          |
    | OS-EXT-SRV-ATTR:instance_name        | instance-00000009                             |
    | OS-EXT-STS:power_state               | 0                                             |
    | OS-EXT-STS:task_state                | scheduling                                    |
    | OS-EXT-STS:vm_state                  | building                                      |
    | OS-SRV-USG:launched_at               | None                                          |
    | OS-SRV-USG:terminated_at             | None                                          |
    | accessIPv4                           |                                               |
    | accessIPv6                           |                                               |
    | addresses                            |                                               |
    | adminPass                            | Fn85skabdxBL                                  |
    | config_drive                         |                                               |
    | created                              | 2016-09-19T15:07:42Z                          |
    | flavor                               | m1.tiny (1)                                   |
    | hostId                               |                                               |
    | id                                   | 04222b73-1a6e-4c2a-9af4-ef3d17d521ff          |
    | image                                | cirros (4aaec87d-c655-4856-8618-b2dada3a2b11) |
    | key_name                             | None                                          |
    | name                                 | demo-instance1                                |
    | os-extended-volumes:volumes_attached | []                                            |
    | progress                             | 0                                             |
    | project_id                           | d44c19e056674381b86430575184b167              |
    | properties                           |                                               |
    | security_groups                      | [{u'name': u'default'}]                       |
    | status                               | BUILD                                         |
    | updated                              | 2016-09-19T15:07:42Z                          |
    | user_id                              | 331afbeb322d4c559a181e19051ae362              |
    +--------------------------------------+-----------------------------------------------+
  5. Check the instance status. The Networks field
    contains an IP address from the subnet having the
    compute:nova service type.

    $ openstack server list
    +--------------------------------------+-----------------+---------+---------------------+--------+---------+
    | ID                                   | Name            | Status  | Networks            | Image  | Flavor  |
    +--------------------------------------+-----------------+---------+---------------------+--------+---------+
    | 20181f46-5cd2-4af8-9af0-f4cf5c983008 | demo-instance1  | ACTIVE  | demo-net1=192.0.2.3 | cirros | m1.tiny |
    +--------------------------------------+-----------------+---------+---------------------+--------+---------+

Example 2 – DVR
configuration

The following example outlines how you can configure service subnets
in a DVR-enabled deployment, with the goal of minimizing public IP
address consumption. This example uses three subnets on the same
external network:

  • 192.0.2.0/24 for instance floating IP addresses
  • 198.51.100.0/24 for floating IP agent gateway IPs configured on
    compute nodes
  • 203.0.113.0/25 for all other IP allocations on the external
    network

This example uses again the private network, demo-net1
(b5b729d8-31cc-4d2c-8284-72b3291fec02) which was created in Example 1 –
Proof-of-concept
.

The output of the commands is not always shown since it is very
similar to the above.

  1. Create an external network:

    $ openstack network create --external demo-ext-net
  2. Create a subnet on the external network for the instance floating
    IP addresses. This uses the network:floatingip service
    type.

    $ openstack subnet create demo-floating-ip-subnet \
      --subnet-range 192.0.2.0/24 --no-dhcp \
      --service-type 'network:floatingip' --network demo-ext-net
  3. Create a subnet on the external network for the floating IP agent
    gateway IP addresses, which are configured by DVR on compute nodes. This
    will use the network:floatingip_agent_gateway service
    type.

    $ openstack subnet create demo-floating-ip-agent-gateway-subnet \
      --subnet-range 198.51.100.0/24 --no-dhcp \
      --service-type 'network:floatingip_agent_gateway' \
      --network demo-ext-net
  4. Create a subnet on the external network for all other IP
    addresses allocated on the external network. This will not use any
    service type. It acts as a fall back for allocations that do not match
    either of the above two service subnets.

    $ openstack subnet create demo-other-subnet \
      --subnet-range 203.0.113.0/25 --no-dhcp \
      --network demo-ext-net
  5. Create a router:

    $ openstack router create demo-router
  6. Add an interface to the router on demo-subnet1:

    $ openstack router add subnet demo-router demo-subnet1
  7. Set the external gateway for the router, which will create an
    interface and allocate an IP address on demo-ext-net:

    $ openstack router set --external-gateway demo-ext-net demo-router
  8. Launch an instance on a private network and retrieve the neutron
    port ID that was allocated. As above, use the cirros image
    and m1.tiny flavor:

    $ openstack server create demo-instance1 --flavor m1.tiny \
      --image cirros --nic net-id=b5b729d8-31cc-4d2c-8284-72b3291fec02
    $ openstack port list --server demo-instance1
    +--------------------------------------+------+-------------------+--------------------------------------------------+--------+
    | ID                                   | Name | MAC Address       | Fixed IP Addresses                               | Status |
    +--------------------------------------+------+-------------------+--------------------------------------------------+--------+
    | a752bb24-9bf2-4d37-b9d6-07da69c86f19 |      | fa:16:3e:99:54:32 | ip_address='203.0.113.130',                      | ACTIVE |
    |                                      |      |                   | subnet_id='6e38b23f-0b27-4e3c-8e69-fd23a3df1935' |        |
    +--------------------------------------+------+-------------------+--------------------------------------------------+--------+
  9. Associate a floating IP with the instance port and verify it was
    allocated an IP address from the correct subnet:

    $ openstack floating ip create --port \
      a752bb24-9bf2-4d37-b9d6-07da69c86f19 demo-ext-net
    +---------------------+--------------------------------------+
    | Field               | Value                                |
    +---------------------+--------------------------------------+
    | fixed_ip_address    | 203.0.113.130                        |
    | floating_ip_address | 192.0.2.12                           |
    | floating_network_id | 02d236d5-dad9-4082-bb6b-5245f9f84d13 |
    | id                  | f15cae7f-5e05-4b19-bd25-4bb71edcf3de |
    | port_id             | a752bb24-9bf2-4d37-b9d6-07da69c86f19 |
    | project_id          | d44c19e056674381b86430575184b167     |
    | revision_number     | 1                                    |
    | router_id           | 5a8ca19f-3703-4f81-bc29-db6bc2f528d6 |
    | status              | ACTIVE                               |
    | tags                | []                                   |
    +---------------------+--------------------------------------+
  10. As the admin user, verify the
    neutron routers are allocated IP addresses from their correct subnets.
    Use openstack port list to find ports associated with the
    routers.

    First, the router gateway external port:

    $ openstack port show f148ffeb-3c26-4067-bc5f-5c3dfddae2f5
    +-----------------------+--------------------------------------------------------------------------+
    | Field                 | Value                                                                    |
    +-----------------------+--------------------------------------------------------------------------+
    | admin_state_up        | UP                                                                       |
    | device_id             | 5a8ca19f-3703-4f81-bc29-db6bc2f528d6                                     |
    | device_owner          | network:router_gateway                                                   |
    | extra_dhcp_opts       |                                                                          |
    | fixed_ips             | ip_address='203.0.113.11',                                               |
    |                       | subnet_id='67c251d9-2b7a-4200-99f6-e13785b0334d'                         |
    | id                    | f148ffeb-3c26-4067-bc5f-5c3dfddae2f5                                     |
    | mac_address           | fa:16:3e:2c:0f:69                                                        |
    | network_id            | 02d236d5-dad9-4082-bb6b-5245f9f84d13                                     |
    | revision_number       | 1                                                                        |
    | project_id            |                                                                          |
    | status                | ACTIVE                                                                   |
    | tags                  | []                                                                       |
    +-----------------------+--------------------------------------------------------------------------+

    Second, the router floating IP agent gateway external port:

    $ openstack port show a2d1e756-8ae1-4f96-9aa1-e7ea16a6a68a
    +-----------------------+--------------------------------------------------------------------------+
    | Field                 | Value                                                                    |
    +-----------------------+--------------------------------------------------------------------------+
    | admin_state_up        | UP                                                                       |
    | device_id             | 3d0c98eb-bca3-45cc-8aa4-90ae3deb0844                                     |
    | device_owner          | network:floatingip_agent_gateway                                         |
    | extra_dhcp_opts       |                                                                          |
    | fixed_ips             | ip_address='198.51.100.10',                                              |
    |                       | subnet_id='67c251d9-2b7a-4200-99f6-e13785b0334d'                         |
    | id                    | a2d1e756-8ae1-4f96-9aa1-e7ea16a6a68a                                     |
    | mac_address           | fa:16:3e:f4:5d:fa                                                        |
    | network_id            | 02d236d5-dad9-4082-bb6b-5245f9f84d13                                     |
    | project_id            |                                                                          |
    | revision_number       | 1                                                                        |
    | status                | ACTIVE                                                                   |
    | tags                  | []                                                                       |
    +-----------------------+--------------------------------------------------------------------------+

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