Local IP internal documentation and release note
Closes-Bug: #1930200 Change-Id: I6745afad159270c5ccd9be2e68f96d8dafc1dc04
This commit is contained in:
Oleg Bondarev
Slawek Kaplonski
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@ -47,6 +47,7 @@ Neutron Internals
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layer3
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linuxbridge_agent
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live_migration
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local_ips
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ml2_ext_manager
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network_ip_availability
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objects_usage
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146
doc/source/contributor/internals/local_ips.rst
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146
doc/source/contributor/internals/local_ips.rst
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@ -0,0 +1,146 @@
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..
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Licensed under the Apache License, Version 2.0 (the "License"); you may
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not use this file except in compliance with the License. You may obtain
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a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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License for the specific language governing permissions and limitations
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under the License.
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Convention for heading levels in Neutron devref:
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======= Heading 0 (reserved for the title in a document)
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------- Heading 1
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~~~~~~~ Heading 2
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+++++++ Heading 3
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''''''' Heading 4
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(Avoid deeper levels because they do not render well.)
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Local IP
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========
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Local IP is a virtual IP that can be shared across multiple ports/VMs
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(similar to anycast IP) and is guaranteed to only be reachable within the same
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physical server/node boundaries. The feature is primarily focused on high
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efficiency and performance of the networking data plane for very large scale
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clouds and/or clouds with high network throughput demands.
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Technically it is Neutron API/DB extension + openvswitch agent extension.
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Usage
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-----
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Usage is similar to Floating IP usage. If you want to assign a virtual Local IP
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to one of your VMs:
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- first create Local IP object using network_id or local_port_id input
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parameter: it will be used to allocate/take IP address
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.. code-block:: console
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$ openstack local ip create --network_id <net-id>
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+------------------+--------------------------------------+
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| Field | Value |
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+------------------+--------------------------------------+
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| created_at | 2021-12-01T13:50:24Z |
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| description | |
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| id | b4425e9d-f1d0-4493-a2a8-1d3c7fbe049b |
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| ip_mode | translate |
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| local_ip_address | 172.24.4.10 |
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| local_port_id | 13181907-f258-4381-9516-ca07648ea239 |
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| name | |
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| network_id | be0ec407-e341-4efa-a33a-3e0160afeedc |
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| project_id | b8462a1eba47462ea8c3e4e6adc22e63 |
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| revision_number | 0 |
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| updated_at | 2021-12-01T13:50:24Z |
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+------------------+--------------------------------------+
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- then create Local IP association object using local_ip_id and fixed_port_id
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input parameters, thus assigning Local IP to the needed VM
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.. code-block:: console
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$ openstack local ip association create <local_ip_id> <fixed_port_id>
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+------------------+--------------------------------------+
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| Field | Value |
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+------------------+--------------------------------------+
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| fixed_ip | 10.0.0.194 |
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| fixed_port_id | 8cd37bb6-f7c3-4013-8d97-5c97676678a0 |
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| host | |
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| id | None |
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| local_ip_address | 172.24.4.10 |
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| name | None |
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+------------------+--------------------------------------+
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- Unlike Floating IP you can have many Local IP associations: to VMs on
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different nodes.
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.. warning::
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Assigning two or more fixed ports to the same Local IP on the same node
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is currently not supported. NAT could go either way or not work at all.
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All node's VMs` egress traffic targeting IP address of Local IP object will be
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DNATed to local VM.
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Note: if no Local IP is assigned on a node packets will be redirected to an
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underlying Neutron port IP address.
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Note: in Yoga release only ``translate`` ip_mode is supported (default) -
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it means DNAT will be used for packet redirection. Support for ``passthrough``
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mode (no modifications to IP packets) will be added in next releases.
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OpenVSwitch Agent Impact
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------------------------
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Unconditional changes
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~~~~~~~~~~~~~~~~~~~~~
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- 2 new OF tables are added for br-int:
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- LOCAL_EGRESS_TABLE - to save VLANs of local ports
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- LOCAL_IP_TABLE - for Local IP handling rules
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- both tables has default rule to resubmit packets to TRANSIENT_TABLE;
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- the only modification to packets flow is that egress packets will first
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go through empty LOCAL_EGRESS_TABLE before entering TRANSIENT_TABLE.
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This should be optimized by OVS to have no impact on performance.
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If local_ip agent extension is enabled
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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- LOCAL_EGRESS_TABLE will have a rule to save port's local VLAN to req6.
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This is needed in order to distinguish Local IPs from different nets.
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Then packets will be resubmitted to LOCAL_IP_TABLE which just has one
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default rule unless some local Port is associated with any Local IP.
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If user creates Local IP Association with one of the ports owned by agent
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Following rules will be added to LOCAL_SWITCHING table:
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- local gARP blocker rule to prevent undesired Local IP ARP updates
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from other nodes (including real IP address owner)
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Following rules will be added to LOCAL_IP_TABLE:
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- local arp responder rule to answer local ARP requests for Local IP address
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- Local IP translation flows to do actual DNAT (Local IP -> fixed IP)
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- via conntrack using ``ct`` with ``nat`` action if ``static_nat`` config
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option is `False` (default)
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- via static NAT rules with source/destination (ETH + IP + TCP/UDP ports)
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tuples used for learning back flows - if ``static_nat`` config is `True`
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Yoga release limitations
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------------------------
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- Only IPv4 is supported. IPv6 support will be considered in future releases
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- Only 'openvswitch' ML2 mechanism driver/agent supports the feature
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- No deterministic handling of packets if a node contains multiple local ports
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from same L2 segment associated with the same Local IP
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@ -607,6 +607,14 @@ still valid. It will delete the stale trunk and subports using the procedure spe
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in the previous paragraphs according to the implementation.
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Local IP
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--------
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Local IP is a new feature added in Yoga release. For details on openvswitch
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agent impact please see:
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:doc:`Local IPs <local_ips>`.
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Further Reading
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---------------
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12
releasenotes/notes/local_ip-de07013ea3e49c67.yaml
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12
releasenotes/notes/local_ip-de07013ea3e49c67.yaml
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@ -0,0 +1,12 @@
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---
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features:
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- |
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Local IP - a virtual IP that can be shared across multiple ports/VMs
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(similar to anycast IP) and is guaranteed to only be reachable within
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the same physical server/node boundaries. The feature is primarily focused
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on high efficiency and performance of the networking data plane for very
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large scale clouds and/or clouds with high network throughput demands.
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other:
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- |
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New service plugin and openvswitch agent extension could be configured
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in order to enable Local IP feature: ``local_ip``
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