d3c560b788
Tag support was extended to all resources that support the std attr mechanism. This patch handles a few remaining updates in the docs. This one is also a candidate for backport to pike if warranted. Change-Id: I7dfc7a371e6af64dde09c0e712424b8e647d7027 Closes-Bug: #1706307
381 lines
18 KiB
ReStructuredText
381 lines
18 KiB
ReStructuredText
.. _config-az:
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==================
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Availability zones
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==================
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An availability zone groups network nodes that run services like DHCP, L3, FW,
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and others. It is defined as an agent's attribute on the network node. This
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allows users to associate an availability zone with their resources so that the
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resources get high availability.
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Use case
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--------
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An availability zone is used to make network resources highly available. The
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operators group the nodes that are attached to different power sources under
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separate availability zones and configure scheduling for resources with high
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availability so that they are scheduled on different availability zones.
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Required extensions
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-------------------
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The core plug-in must support the ``availability_zone`` extension. The core
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plug-in also must support the ``network_availability_zone`` extension to
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schedule a network according to availability zones. The ``Ml2Plugin`` supports
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it. The router service plug-in must support the ``router_availability_zone``
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extension to schedule a router according to the availability zones. The
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``L3RouterPlugin`` supports it.
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.. code-block:: console
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$ openstack extension list --network -c Alias -c Name
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+---------------------------+---------------------------+
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| Name | Alias |
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+---------------------------+---------------------------+
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...
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| Network Availability Zone | network_availability_zone |
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...
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| Availability Zone | availability_zone |
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...
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| Router Availability Zone | router_availability_zone |
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...
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+---------------------------+---------------------------+
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Availability zone of agents
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~~~~~~~~~~~~~~~~~~~~~~~~~~~
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The ``availability_zone`` attribute can be defined in ``dhcp-agent`` and
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``l3-agent``. To define an availability zone for each agent, set the
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value into ``[AGENT]`` section of ``/etc/neutron/dhcp_agent.ini`` or
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``/etc/neutron/l3_agent.ini``:
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.. code-block:: ini
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[AGENT]
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availability_zone = zone-1
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To confirm the agent's availability zone:
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.. code-block:: console
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$ openstack network agent show 116cc128-4398-49af-a4ed-3e95494cd5fc
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+---------------------+---------------------------------------------------+
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| Field | Value |
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+---------------------+---------------------------------------------------+
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| admin_state_up | UP |
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| agent_type | DHCP agent |
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| alive | True |
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| availability_zone | zone-1 |
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| binary | neutron-dhcp-agent |
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| configurations | dhcp_driver='neutron.agent.linux.dhcp.Dnsmasq', |
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| | dhcp_lease_duration='86400', |
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| | log_agent_heartbeats='False', networks='2', |
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| | notifies_port_ready='True', ports='6', subnets='4 |
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| created_at | 2016-12-14 00:25:54 |
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| description | None |
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| heartbeat_timestamp | 2016-12-14 06:20:24 |
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| host | ankur-desktop |
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| id | 116cc128-4398-49af-a4ed-3e95494cd5fc |
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| started_at | 2016-12-14 00:25:54 |
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| topic | dhcp_agent |
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+---------------------+---------------------------------------------------+
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$ openstack network agent show 9632309a-2aa4-4304-8603-c4de02c4a55f
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+---------------------+-------------------------------------------------+
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| Field | Value |
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+---------------------+-------------------------------------------------+
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| admin_state_up | UP |
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| agent_type | L3 agent |
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| alive | True |
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| availability_zone | zone-1 |
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| binary | neutron-l3-agent |
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| configurations | agent_mode='legacy', ex_gw_ports='2', |
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| | external_network_bridge='', floating_ips='0', |
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| | gateway_external_network_id='', |
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| | handle_internal_only_routers='True', |
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| | interface_driver='openvswitch', interfaces='4', |
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| | log_agent_heartbeats='False', routers='2' |
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| created_at | 2016-12-14 00:25:58 |
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| description | None |
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| heartbeat_timestamp | 2016-12-14 06:20:28 |
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| host | ankur-desktop |
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| id | 9632309a-2aa4-4304-8603-c4de02c4a55f |
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| started_at | 2016-12-14 00:25:58 |
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| topic | l3_agent |
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+---------------------+-------------------------------------------------+
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Availability zone related attributes
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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The following attributes are added into network and router:
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.. list-table::
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:header-rows: 1
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:widths: 25 10 10 10 50
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* - Attribute name
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- Access
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- Required
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- Input type
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- Description
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* - availability_zone_hints
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- RW(POST only)
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- No
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- list of string
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- availability zone candidates for the resource
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* - availability_zones
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- RO
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- N/A
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- list of string
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- availability zones for the resource
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Use ``availability_zone_hints`` to specify the zone in which the resource is
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hosted:
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.. code-block:: console
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$ openstack network create --availability-zone-hint zone-1 \
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--availability-zone-hint zone-2 net1
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+---------------------------+--------------------------------------+
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| Field | Value |
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+---------------------------+--------------------------------------+
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| admin_state_up | UP |
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| availability_zone_hints | zone-1 |
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| | zone-2 |
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| availability_zones | |
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| created_at | 2016-12-14T06:23:36Z |
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| description | |
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| headers | |
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| id | ad88e059-e7fa-4cf7-8857-6731a2a3a554 |
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| ipv4_address_scope | None |
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| ipv6_address_scope | None |
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| mtu | 1450 |
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| name | net1 |
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| port_security_enabled | True |
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| project_id | cfd1889ac7d64ad891d4f20aef9f8d7c |
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| provider:network_type | vxlan |
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| provider:physical_network | None |
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| provider:segmentation_id | 77 |
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| revision_number | 3 |
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| router:external | Internal |
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| shared | False |
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| status | ACTIVE |
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| subnets | |
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| tags | [] |
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| updated_at | 2016-12-14T06:23:37Z |
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+---------------------------+--------------------------------------+
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.. code-block:: console
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$ openstack router create --ha --availability-zone-hint zone-1 \
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--availability-zone-hint zone-2 router1
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+-------------------------+--------------------------------------+
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| Field | Value |
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+-------------------------+--------------------------------------+
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| admin_state_up | UP |
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| availability_zone_hints | zone-1 |
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| | zone-2 |
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| availability_zones | |
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| created_at | 2016-12-14T06:25:40Z |
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| description | |
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| distributed | False |
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| external_gateway_info | null |
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| flavor_id | None |
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| ha | False |
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| headers | |
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| id | ced10262-6cfe-47c1-8847-cd64276a868c |
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| name | router1 |
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| project_id | cfd1889ac7d64ad891d4f20aef9f8d7c |
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| revision_number | 3 |
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| routes | |
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| status | ACTIVE |
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| tags | [] |
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| updated_at | 2016-12-14T06:25:40Z |
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+-------------------------+--------------------------------------+
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Availability zone is selected from ``default_availability_zones`` in
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``/etc/neutron/neutron.conf`` if a resource is created without
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``availability_zone_hints``:
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.. code-block:: ini
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default_availability_zones = zone-1,zone-2
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To confirm the availability zone defined by the system:
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.. code-block:: console
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$ openstack availability zone list
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+-----------+-------------+
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| Zone Name | Zone Status |
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+-----------+-------------+
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| zone-1 | available |
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| zone-2 | available |
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| zone-1 | available |
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| zone-2 | available |
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+-----------+-------------+
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Look at the ``availability_zones`` attribute of each resource to confirm in
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which zone the resource is hosted:
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.. code-block:: console
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$ openstack network show net1
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+---------------------------+--------------------------------------+
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| Field | Value |
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+---------------------------+--------------------------------------+
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| admin_state_up | UP |
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| availability_zone_hints | zone-1 |
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| | zone-2 |
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| availability_zones | zone-1 |
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| | zone-2 |
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| created_at | 2016-12-14T06:23:36Z |
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| description | |
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| headers | |
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| id | ad88e059-e7fa-4cf7-8857-6731a2a3a554 |
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| ipv4_address_scope | None |
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| ipv6_address_scope | None |
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| mtu | 1450 |
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| name | net1 |
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| port_security_enabled | True |
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| project_id | cfd1889ac7d64ad891d4f20aef9f8d7c |
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| provider:network_type | vxlan |
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| provider:physical_network | None |
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| provider:segmentation_id | 77 |
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| revision_number | 3 |
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| router:external | Internal |
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| shared | False |
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| status | ACTIVE |
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| subnets | |
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| tags | [] |
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| updated_at | 2016-12-14T06:23:37Z |
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+---------------------------+--------------------------------------+
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.. code-block:: console
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$ openstack router show router1
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+-------------------------+--------------------------------------+
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| Field | Value |
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+-------------------------+--------------------------------------+
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| admin_state_up | UP |
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| availability_zone_hints | zone-1 |
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| | zone-2 |
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| availability_zones | zone-1 |
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| | zone-2 |
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| created_at | 2016-12-14T06:25:40Z |
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| description | |
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| distributed | False |
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| external_gateway_info | null |
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| flavor_id | None |
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| ha | False |
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| headers | |
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| id | ced10262-6cfe-47c1-8847-cd64276a868c |
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| name | router1 |
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| project_id | cfd1889ac7d64ad891d4f20aef9f8d7c |
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| revision_number | 3 |
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| routes | |
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| status | ACTIVE |
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| tags | [] |
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| updated_at | 2016-12-14T06:25:40Z |
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+-------------------------+--------------------------------------+
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.. note::
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The ``availability_zones`` attribute does not have a value until the
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resource is scheduled. Once the Networking service schedules the resource
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to zones according to ``availability_zone_hints``, ``availability_zones``
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shows in which zone the resource is hosted practically. The
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``availability_zones`` may not match ``availability_zone_hints``. For
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example, even if you specify a zone with ``availability_zone_hints``, all
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agents of the zone may be dead before the resource is scheduled. In
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general, they should match, unless there are failures or there is no
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capacity left in the zone requested.
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Availability zone aware scheduler
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Network scheduler
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-----------------
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Set ``AZAwareWeightScheduler`` to ``network_scheduler_driver`` in
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``/etc/neutron/neutron.conf`` so that the Networking service schedules a
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network according to the availability zone:
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.. code-block:: ini
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network_scheduler_driver = neutron.scheduler.dhcp_agent_scheduler.AZAwareWeightScheduler
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dhcp_load_type = networks
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The Networking service schedules a network to one of the agents within the
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selected zone as with ``WeightScheduler``. In this case, scheduler refers to
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``dhcp_load_type`` as well.
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Router scheduler
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----------------
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Set ``AZLeastRoutersScheduler`` to ``router_scheduler_driver`` in file
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``/etc/neutron/neutron.conf`` so that the Networking service schedules a router
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according to the availability zone:
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.. code-block:: ini
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router_scheduler_driver = neutron.scheduler.l3_agent_scheduler.AZLeastRoutersScheduler
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The Networking service schedules a router to one of the agents within the
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selected zone as with ``LeastRouterScheduler``.
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Achieving high availability with availability zone
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Although, the Networking service provides high availability for routers and
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high availability and fault tolerance for networks' DHCP services, availability
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zones provide an extra layer of protection by segmenting a Networking service
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deployment in isolated failure domains. By deploying HA nodes across different
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availability zones, it is guaranteed that network services remain available in
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face of zone-wide failures that affect the deployment.
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This section explains how to get high availability with the availability zone
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for L3 and DHCP. You should naturally set above configuration options for the
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availability zone.
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L3 high availability
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--------------------
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Set the following configuration options in file ``/etc/neutron/neutron.conf``
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so that you get L3 high availability.
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.. code-block:: ini
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l3_ha = True
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max_l3_agents_per_router = 3
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HA routers are created on availability zones you selected when creating the
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router.
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DHCP high availability
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----------------------
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Set the following configuration options in file ``/etc/neutron/neutron.conf``
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so that you get DHCP high availability.
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.. code-block:: ini
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dhcp_agents_per_network = 2
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DHCP services are created on availability zones you selected when creating the
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network.
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