taikun.cloud

Taikun Logo

Taikun OCP Guide

Table of Contents

Network segment ranges

The network segment range service exposes the segment range
management to be administered via the Neutron API. In addition, it
introduces the ability for the administrator to control the segment
ranges globally or on a per-tenant basis.

Why you need it

Before Stein, network segment ranges were configured as an entry in
ML2 config file ml2_conf.ini that was statically defined
for tenant network allocation and therefore had to be managed as part of
the host deployment and management. When a regular tenant user creates a
network, Neutron assigns the next free segmentation ID (VLAN ID, VNI
etc.) from the configured segment ranges. Only an administrator can
assign a specific segment ID via the provider extension.

The network segment range management service provides the following
capabilities that the administrator may be interested in:

  1. To check out the network segment ranges defined by the operators in
    the ML2 config file so that the admin can use this information to make
    segment range allocation.
  2. To dynamically create and assign network segment ranges, which can
    help with the distribution of the underlying network connection mapping
    for privacy or dedicated business connection needs. This includes:

    • global shared network segment ranges
    • tenant-specific network segment ranges
  3. To dynamically update a network segment range to offer the ability
    to adapt to the connection mapping changes.
  4. To dynamically manage a network segment range when there are no
    segment ranges defined within the ML2 config file
    ml2_conf.ini and no restart of the Neutron server is
    required in this situation.
  5. To check the availability and usage statistics of network segment
    ranges.

How it works

A network segment range manages a set of segments from which
self-service networks can be allocated. The network segment range
management service is admin-only.

As a regular project in an OpenStack cloud, you can not create a
network segment range of your own and you just create networks in
regular way.

If you are an admin, you can create a network segment range which can
be shared (i.e. used by any regular project) or tenant-specific (i.e.
assignment on a per-tenant basis). Your network segment ranges will not
be visible to any other regular projects. Other CRUD operations are also
supported.

When a tenant allocates a segment, it will first be allocated from an
available segment range assigned to the tenant, and then a shared range
if no tenant specific allocation is possible.

Default network segment
ranges

A set of default network segment ranges are created out
of the values defined in the ML2 config file:
network_vlan_ranges for ml2_type_vlan,
vni_ranges for ml2_type_vxlan,
tunnel_id_ranges for ml2_type_gre and
vni_ranges for ml2_type_geneve. They will be reloaded when
Neutron server starts or restarts. The default network
segment ranges are read-only, but will be treated as any
other shared ranges on segment allocation.

The administrator can use the default network segment range
information to make shared and/or per-tenant range creation and
assignment.

Example configuration

Controller node

  1. Enable the network segment range service plugin by appending
    network_segment_range to the list of
    service_plugins in the neutron.conf file on
    all nodes running the neutron-server service:

    [DEFAULT]
    # ...
    service_plugins = ...,network_segment_range,...
  2. Restart the neutron-server service.

Verify service operation

  1. Source the administrative project credentials and list the enabled
    extensions.
  2. Use the command openstack extension list --network to verify that
    the Neutron Network Segment Range extension with Alias
    network-segment-range is enabled.
$ openstack extension list --network
+-------------------------------+-----------------------+-----------------------------------------------------------+
| Name                          | Alias                 | Description                                               |
+-------------------------------+-----------------------+-----------------------------------------------------------+
| ......                        | ......                | ......                                                    |
+-------------------------------+-----------------------+-----------------------------------------------------------+
| Neutron Network Segment Range | network-segment-range | Provides support for the network segment range management |
+-------------------------------+-----------------------+-----------------------------------------------------------+
| ......                        | ......                | ......                                                    |
+-------------------------------+-----------------------+-----------------------------------------------------------+

Workflow

At a high level, the basic workflow for a network segment range
creation is the following:

  1. The Cloud administrator:
    • Lists the existing network segment ranges.
    • Creates a shared or a tenant-specific network segment range based on
      the requirement.
  2. A regular tenant creates a network in regular way. The network
    created will automatically allocate a segment from the segment ranges
    assigned to the tenant or shared if no tenant specific range
    available.

At a high level, the basic workflow for a network segment range
update is the following:

  1. The Cloud administrator:
    • Lists the existing network segment ranges and identifies the one
      that needs to be updated.
    • Updates the network segment range based on the requirement.
  2. A regular tenant creates a network in regular way. The network
    created will automatically allocate a segment from the updated network
    segment ranges available.

List
the network segment ranges or show a network segment range

As admin, list the existing network segment ranges:

$ openstack network segment range list
+--------------------------------------+-------------------+---------+--------+----------------------------------+--------------+------------------+------------+------------+
| ID                                   | Name              | Default | Shared | Project ID                       | Network Type | Physical Network | Minimum ID | Maximum ID |
+--------------------------------------+-------------------+---------+--------+----------------------------------+--------------+------------------+------------+------------+
| 20ce94e1-4e51-4aa0-a5f1-26bdfb5bd90e |                   | True    | True   | None                             | vxlan        | None             |          1 |        200 |
| 4b7af684-ec97-422d-ba38-8b9c2919ae67 | test_range_3      | False   | False  | 7011dc7fccac4efda89dc3b7f0d0975a | gre          | None             |        100 |        120 |
| a021e582-6b0f-49f5-90cb-79a670c61973 |                   | True    | True   | None                             | vlan         | default          |          1 |        100 |
| a3373630-969b-4ce9-bae7-dff0f8fa2f92 | test_range_2      | False   | True   | None                             | vxlan        | None             |        501 |        505 |
| a5707a8f-76f0-4f90-9aa7-c42bf54e94b5 |                   | True    | True   | None                             | gre          | None             |          1 |        150 |
| aad1b55b-43f1-46f9-8c35-85f270863ed6 |                   | True    | True   | None                             | geneve       | None             |          1 |        120 |
| e3233178-2866-4f40-b794-7c6fecdc8655 | test_range_1      | False   | False  | 7011dc7fccac4efda89dc3b7f0d0975a | vlan         | group0-data0     |         11 |         11 |
+--------------------------------------+-------------------+---------+--------+----------------------------------+--------------+------------------+------------+------------+

The network segment ranges with Default as
True are the ranges specified by the operators in the ML2
config file. Besides, there are also shared and tenant specific network
segment ranges created by the admin previously.

The admin is also able to check/show the detailed information (e.g.
availability and usage statistics) of a network segment range:

$ openstack network segment range show test_range_1
+------------------+-----------------------------------------------+
| Field            | Value                                         |
+------------------+-----------------------------------------------+
| available        | []                                            |
| default          | False                                         |
| id               | e3233178-2866-4f40-b794-7c6fecdc8655          |
| location         | None                                          |
| maximum          | 11                                            |
| minimum          | 11                                            |
| name             | test_range_1                                  |
| network_type     | vlan                                          |
| physical_network | group0-data0                                  |
| project_id       | 7011dc7fccac4efda89dc3b7f0d0975a              |
| shared           | False                                         |
| used             | {u'7011dc7fccac4efda89dc3b7f0d0975a': ['11']} |
+------------------+-----------------------------------------------+

Create or update the
network segment range

As admin, create a network segment range based on your
requirement:

$ openstack network segment range create --private --project demo \
--network-type vxlan --minimum 120 --maximum 140 test_range_4
+------------------+--------------------------------------+
| Field            | Value                                |
+------------------+--------------------------------------+
| available        | ['120-140']                          |
| default          | False                                |
| id               | c016dcda-5bc3-4e98-b41f-6773e92fcd2d |
| location         | None                                 |
| maximum          | 140                                  |
| minimum          | 120                                  |
| name             | test_range_4                         |
| network_type     | vxlan                                |
| physical_network | None                                 |
| project_id       | 7011dc7fccac4efda89dc3b7f0d0975a     |
| shared           | False                                |
| used             | {}                                   |
+------------------+--------------------------------------+

Update a network segment range based on your requirement:

$ openstack network segment range set --minimum 100 --maximum 150 \
test_range_4

Create a tenant network

Now, as project demo (to source the client environment
script demo-openrc for demo project according
to https://docs.openstack.org/keystone/latest/install/keystone-openrc-rdo.html),
create a network in a regular way.

$ source demo-openrc
$ openstack network create test_net
+---------------------------+--------------------------------------+
| Field                     | Value                                |
+---------------------------+--------------------------------------+
| admin_state_up            | UP                                   |
| availability_zone_hints   |                                      |
| availability_zones        |                                      |
| created_at                | 2019-02-25T23:20:36Z                 |
| description               |                                      |
| dns_domain                |                                      |
| id                        | 39e5b95c-ad7a-40b5-9ec1-a4b4a8a43f14 |
| ipv4_address_scope        | None                                 |
| ipv6_address_scope        | None                                 |
| is_default                | False                                |
| is_vlan_transparent       | None                                 |
| location                  | None                                 |
| mtu                       | 1450                                 |
| name                      | test_net                             |
| port_security_enabled     | True                                 |
| project_id                | 7011dc7fccac4efda89dc3b7f0d0975a     |
| provider:network_type     | vxlan                                |
| provider:physical_network | None                                 |
| provider:segmentation_id  | None                                  |
| qos_policy_id             | None                                 |
| revision_number           | 2                                    |
| router:external           | Internal                             |
| segments                  | None                                 |
| shared                    | False                                |
| status                    | ACTIVE                               |
| subnets                   |                                      |
| tags                      |                                      |
| updated_at                | 2019-02-25T23:20:36Z                 |
+---------------------------+--------------------------------------+

Then, switch back to the admin to check the segmentation ID of the
tenant network created.

$ source admin-openrc
$ openstack network show test_net
+---------------------------+--------------------------------------+
| Field                     | Value                                |
+---------------------------+--------------------------------------+
| admin_state_up            | UP                                   |
| availability_zone_hints   |                                      |
| availability_zones        |                                      |
| created_at                | 2019-02-25T23:20:36Z                 |
| description               |                                      |
| dns_domain                |                                      |
| id                        | 39e5b95c-ad7a-40b5-9ec1-a4b4a8a43f14 |
| ipv4_address_scope        | None                                 |
| ipv6_address_scope        | None                                 |
| is_default                | False                                |
| is_vlan_transparent       | None                                 |
| location                  | None                                 |
| mtu                       | 1450                                 |
| name                      | test_net                             |
| port_security_enabled     | True                                 |
| project_id                | 7011dc7fccac4efda89dc3b7f0d0975a     |
| provider:network_type     | vxlan                                |
| provider:physical_network | None                                 |
| provider:segmentation_id  | 137                                  |
| qos_policy_id             | None                                 |
| revision_number           | 2                                    |
| router:external           | Internal                             |
| segments                  | None                                 |
| shared                    | False                                |
| status                    | ACTIVE                               |
| subnets                   |                                      |
| tags                      |                                      |
| updated_at                | 2019-02-25T23:20:36Z                 |
+---------------------------+--------------------------------------+

The tenant network created automatically allocates a segment with
segmentation ID 137 from the network segment range with
segmentation ID range 120-140 that is assigned to the
tenant.

If no more available segment in the network segment range assigned to
this tenant, then the segment allocation would refer to the
shared segment ranges to check whether there’s one segment
available. If still there is no segment available, the allocation will
fail as follows:

$ openstack network create test_net
$ Unable to create the network. No tenant network is available for
  allocation.

In this case, the admin is advised to check the availability and
usage statistics of the related network segment ranges in order to take
further actions (e.g. enlarging a segment range etc.).

Known limitations

  • This service plugin is only compatible with ML2 core plugin for now.
    However, it is possible for other core plugins to support this feature
    with a follow-on effort.

taikun-logo-icon

Explore Taikun CloudWorks in 2 Minutes!