245 lines
10 KiB
ReStructuredText
245 lines
10 KiB
ReStructuredText
.. _config-auto-allocation:
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==========================================
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Automatic allocation of network topologies
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==========================================
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The auto-allocation feature introduced in Mitaka simplifies the procedure of
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setting up an external connectivity for end-users, and is also known as **Get
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Me A Network**.
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Previously, a user had to configure a range of networking resources to boot
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a server and get access to the Internet. For example, the following steps
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are required:
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* Create a network
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* Create a subnet
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* Create a router
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* Uplink the router on an external network
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* Downlink the router on the previously created subnet
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These steps need to be performed on each logical segment that a VM needs to
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be connected to, and may require networking knowledge the user might not
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have.
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This feature is designed to automate the basic networking provisioning for
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projects. The steps to provision a basic network are run during instance
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boot, making the networking setup hands-free.
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To make this possible, provide a default external network and default
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subnetpools (one for IPv4, or one for IPv6, or one of each) so that the
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Networking service can choose what to do in lieu of input. Once these are in
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place, users can boot their VMs without specifying any networking details.
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The Compute service will then use this feature automatically to wire user
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VMs.
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Enabling the deployment for auto-allocation
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-------------------------------------------
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To use this feature, the neutron service must have the following extensions
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enabled:
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* ``auto-allocated-topology``
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* ``subnet_allocation``
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* ``external-net``
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* ``router``
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Before the end-user can use the auto-allocation feature, the operator must
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create the resources that will be used for the auto-allocated network
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topology creation. To perform this task, proceed with the following steps:
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#. Set up a default external network
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Setting up an external network is described in
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`OpenStack Networking Guide <./archives/adv-features.html>`_.
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Assuming the external network to be used for the auto-allocation feature
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is named ``public``, make it the ``default`` external network
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with the following command:
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.. code-block:: console
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$ openstack network set public --default
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.. note::
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The flag ``--default`` (and ``--no-default`` flag) is only effective
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with external networks and has no effects on regular (or internal)
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networks.
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#. Create default subnetpools
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The auto-allocation feature requires at least one default
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subnetpool. One for IPv4, or one for IPv6, or one of each.
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.. code-block:: console
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$ openstack subnet pool create --share --default \
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--pool-prefix 192.0.2.0/24 --default-prefix-length 26 \
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shared-default
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+-------------------+--------------------------------------+
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| Field | Value |
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+-------------------+--------------------------------------+
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| address_scope_id | None |
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| created_at | 2017-01-12T15:10:34Z |
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| default_prefixlen | 26 |
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| default_quota | None |
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| description | |
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| headers | |
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| id | b41b7b9c-de57-4c19-b1c5-731985bceb7f |
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| ip_version | 4 |
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| is_default | True |
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| max_prefixlen | 32 |
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| min_prefixlen | 8 |
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| name | shared-default |
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| prefixes | 192.0.2.0/24 |
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| project_id | 86acdbd1d72745fd8e8320edd7543400 |
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| revision_number | 1 |
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| shared | True |
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| tags | [] |
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| updated_at | 2017-01-12T15:10:34Z |
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+-------------------+--------------------------------------+
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$ openstack subnet pool create --share --default \
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--pool-prefix 2001:db8:8000::/48 --default-prefix-length 64 \
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default-v6
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+-------------------+--------------------------------------+
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| Field | Value |
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+-------------------+--------------------------------------+
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| address_scope_id | None |
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| created_at | 2017-01-12T15:14:35Z |
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| default_prefixlen | 64 |
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| default_quota | None |
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| description | |
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| headers | |
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| id | 6f387016-17f0-4564-96ad-e34775b6ea14 |
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| ip_version | 6 |
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| is_default | True |
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| max_prefixlen | 128 |
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| min_prefixlen | 64 |
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| name | default-v6 |
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| prefixes | 2001:db8:8000::/48 |
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| project_id | 86acdbd1d72745fd8e8320edd7543400 |
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| revision_number | 1 |
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| shared | True |
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| tags | [] |
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| updated_at | 2017-01-12T15:14:35Z |
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+-------------------+--------------------------------------+
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Get Me A Network
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----------------
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In a deployment where the operator has set up the resources as described above,
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they can get their auto-allocated network topology as follows:
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.. code-block:: console
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$ openstack network auto allocated topology create --or-show
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+------------+--------------------------------------+
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| Field | Value |
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+------------+--------------------------------------+
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| id | a380c780-d6cd-4510-a4c0-1a6ec9b85a29 |
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| name | None |
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| project_id | cfd1889ac7d64ad891d4f20aef9f8d7c |
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+------------+--------------------------------------+
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.. note::
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When the ``--or-show`` option is used the command returns the topology
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information if it already exists.
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Operators (and users with admin role) can get the auto-allocated topology for a
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project by specifying the project ID:
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.. code-block:: console
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$ openstack network auto allocated topology create --project \
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cfd1889ac7d64ad891d4f20aef9f8d7c --or-show
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+------------+--------------------------------------+
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| Field | Value |
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+------------+--------------------------------------+
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| id | a380c780-d6cd-4510-a4c0-1a6ec9b85a29 |
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| name | None |
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| project_id | cfd1889ac7d64ad891d4f20aef9f8d7c |
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+------------+--------------------------------------+
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The ID returned by this command is a network which can be used for booting
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a VM.
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.. code-block:: console
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$ openstack server create --flavor m1.small --image \
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cirros-0.3.5-x86_64-uec --nic \
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net-id=8b835bfb-cae2-4acc-b53f-c16bb5f9a7d0 vm1
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The auto-allocated topology for a user never changes. In practice, when a user
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boots a server omitting the ``--nic`` option, and there is more than one
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network available, the Compute service will invoke the API behind
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``auto allocated topology create``, fetch the network UUID, and pass it on
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during the boot process.
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Validating the requirements for auto-allocation
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-----------------------------------------------
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To validate that the required resources are correctly set up for
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auto-allocation, without actually provisioning anything, use
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the ``--check-resources`` option:
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.. code-block:: console
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$ openstack network auto allocated topology create --check-resources
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Deployment error: No default router:external network.
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$ openstack network set public --default
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$ openstack network auto allocated topology create --check-resources
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Deployment error: No default subnetpools defined.
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$ openstack subnet pool set shared-default --default
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$ openstack network auto allocated topology create --check-resources
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+---------+-------+
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| Field | Value |
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+---------+-------+
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| dry-run | pass |
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+---------+-------+
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The validation option behaves identically for all users. However, it
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is considered primarily an admin or service utility since it is the
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operator who must set up the requirements.
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Project resources created by auto-allocation
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--------------------------------------------
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The auto-allocation feature creates one network topology in every project
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where it is used. The auto-allocated network topology for a project contains
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the following resources:
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+--------------------+------------------------------+
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|Resource |Name |
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+====================+==============================+
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|network |``auto_allocated_network`` |
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+--------------------+------------------------------+
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|subnet (IPv4) |``auto_allocated_subnet_v4`` |
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+--------------------+------------------------------+
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|subnet (IPv6) |``auto_allocated_subnet_v6`` |
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+--------------------+------------------------------+
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|router |``auto_allocated_router`` |
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+--------------------+------------------------------+
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Compatibility notes
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-------------------
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Nova uses the ``auto allocated topology`` feature with API micro
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version 2.37 or later. This is because, unlike the neutron feature
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which was implemented in the Mitaka release, the integration for
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nova was completed during the Newton release cycle. Note that
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the CLI option ``--nic`` can be omitted regardless of the microversion
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used as long as there is no more than one network available to the
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project, in which case nova fails with a 400 error because it
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does not know which network to use. Furthermore, nova does not start
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using the feature, regardless of whether or not a user requests
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micro version 2.37 or later, unless all of the ``nova-compute``
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services are running Newton-level code.
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