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..
Licensed under the Apache License, Version 2.0 (the "License"); you may
not use this file except in compliance with the License. You may obtain
a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
License for the specific language governing permissions and limitations
under the License.
Convention for heading levels in Open vSwitch documentation:
======= Heading 0 (reserved for the title in a document)
------- Heading 1
~~~~~~~ Heading 2
+++++++ Heading 3
''''''' Heading 4
Avoid deeper levels because they do not render well.
========
Releases
========
Q: What does it mean for an Open vSwitch release to be LTS (long-term support)?
A: All official releases have been through a comprehensive testing process
and are suitable for production use. Planned releases occur twice a year.
If a significant bug is identified in an LTS release, we will provide an
updated release that includes the fix. Releases that are not LTS may not
be fixed and may just be supplanted by the next major release. The current
LTS release is 2.5.x.
For more information on the Open vSwitch release process, refer to
:doc:`/internals/release-process`.
Q: What Linux kernel versions does each Open vSwitch release work with?
A: The following table lists the Linux kernel versions against which the
given versions of the Open vSwitch kernel module will successfully build.
The Linux kernel versions are upstream kernel versions, so Linux kernels
modified from the upstream sources may not build in some cases even if they
are based on a supported version. This is most notably true of Red Hat
Enterprise Linux (RHEL) kernels, which are extensively modified from
upstream.
============ ==============
Open vSwitch Linux kernel
============ ==============
1.4.x 2.6.18 to 3.2
1.5.x 2.6.18 to 3.2
1.6.x 2.6.18 to 3.2
1.7.x 2.6.18 to 3.3
1.8.x 2.6.18 to 3.4
1.9.x 2.6.18 to 3.8
1.10.x 2.6.18 to 3.8
1.11.x 2.6.18 to 3.8
2.0.x 2.6.32 to 3.10
2.1.x 2.6.32 to 3.11
2.3.x 2.6.32 to 3.14
2.4.x 2.6.32 to 4.0
2.5.x 2.6.32 to 4.3
2.6.x 3.10 to 4.7
2.7.x 3.10 to 4.9
2.8.x 3.10 to 4.12
2.9.x 3.10 to 4.13
2.10.x 3.10 to 4.14
============ ==============
Open vSwitch userspace should also work with the Linux kernel module built
into Linux 3.3 and later.
Open vSwitch userspace is not sensitive to the Linux kernel version. It
should build against almost any kernel, certainly against 2.6.32 and later.
Q: Are all features available with all datapaths?
A: Open vSwitch supports different datapaths on different platforms. Each
datapath has a different feature set: the following tables try to summarize
the status.
Supported datapaths:
Linux upstream
The datapath implemented by the kernel module shipped with Linux
upstream. Since features have been gradually introduced into the kernel,
the table mentions the first Linux release whose OVS module supports the
feature.
Linux OVS tree
The datapath implemented by the Linux kernel module distributed with the
OVS source tree.
Userspace
Also known as DPDK, dpif-netdev or dummy datapath. It is the only
datapath that works on NetBSD, FreeBSD and Mac OSX.
Hyper-V
Also known as the Windows datapath.
The following table lists the datapath supported features from an Open
vSwitch user's perspective.
===================== ============== ============== ========= =======
Feature Linux upstream Linux OVS tree Userspace Hyper-V
===================== ============== ============== ========= =======
NAT 4.6 YES Yes NO
Connection tracking 4.3 YES PARTIAL PARTIAL
Tunnel - LISP NO YES NO NO
Tunnel - STT NO YES NO YES
Tunnel - GRE 3.11 YES YES YES
Tunnel - VXLAN 3.12 YES YES YES
Tunnel - Geneve 3.18 YES YES YES
Tunnel - GRE-IPv6 NO NO YES NO
Tunnel - VXLAN-IPv6 4.3 YES YES NO
Tunnel - Geneve-IPv6 4.4 YES YES NO
QoS - Policing YES YES YES NO
QoS - Shaping YES YES NO NO
sFlow YES YES YES NO
IPFIX 3.10 YES YES NO
Set action YES YES YES PARTIAL
NIC Bonding YES YES YES YES
Multiple VTEPs YES YES YES YES
===================== ============== ============== ========= =======
Do note, however:
* Only a limited set of flow fields is modifiable via the set action by the
Hyper-V datapath.
The following table lists features that do not *directly* impact an Open
vSwitch user, e.g. because their absence can be hidden by the ofproto layer
(usually this comes with a performance penalty).
===================== ============== ============== ========= =======
Feature Linux upstream Linux OVS tree Userspace Hyper-V
===================== ============== ============== ========= =======
SCTP flows 3.12 YES YES YES
MPLS 3.19 YES YES YES
UFID 4.0 YES YES NO
Megaflows 3.12 YES YES NO
Masked set action 4.0 YES YES NO
Recirculation 3.19 YES YES YES
TCP flags matching 3.13 YES YES NO
Validate flow actions YES YES N/A NO
Multiple datapaths YES YES YES NO
Tunnel TSO - STT N/A YES NO YES
===================== ============== ============== ========= =======
Q: What DPDK version does each Open vSwitch release work with?
A: The following table lists the DPDK version against which the given
versions of Open vSwitch will successfully build.
============ =======
Open vSwitch DPDK
============ =======
2.2.x 1.6
2.3.x 1.6
2.4.x 2.0
2.5.x 2.2
2.6.x 16.07.2
2.7.x 16.11.7
2.8.x 17.05.2
2.9.x 17.11.3
============ =======
Q: Are all the DPDK releases that OVS versions work with maintained?
No. DPDK follows YY.MM.n (Year.Month.Number) versioning.
Typically, all DPDK releases get a stable YY.MM.1 update with bugfixes 3
months after the YY.MM.0 release. In some cases there may also be a
YY.MM.2 release.
DPDK LTS releases start once a year at YY.11.0 and are maintained for
two years, with YY.MM.n+1 releases around every 3 months.
The latest information about DPDK stable and LTS releases can be found
at `DPDK stable`_.
.. _DPDK stable: http://dpdk.org/doc/guides/contributing/stable.html
Q: I get an error like this when I configure Open vSwitch:
configure: error: Linux kernel in <dir> is version <x>, but
version newer than <y> is not supported (please refer to the
FAQ for advice)
What should I do?
A: You have the following options:
- Use the Linux kernel module supplied with the kernel that you are using.
(See also the following FAQ.)
- If there is a newer released version of Open vSwitch, consider building
that one, because it may support the kernel that you are building
against. (To find out, consult the table in the previous FAQ.)
- The Open vSwitch "master" branch may support the kernel that you are
using, so consider building the kernel module from "master".
All versions of Open vSwitch userspace are compatible with all versions of
the Open vSwitch kernel module, so you do not have to use the kernel module
from one source along with the userspace programs from the same source.
Q: What features are not available in the Open vSwitch kernel datapath that
ships as part of the upstream Linux kernel?
A: The kernel module in upstream Linux does not include support for LISP.
Work is in progress to add support for LISP to the upstream Linux version
of the Open vSwitch kernel module. For now, if you need this feature, use
the kernel module from the Open vSwitch distribution instead of the
upstream Linux kernel module.
Certain features require kernel support to function or to have reasonable
performance. If the ovs-vswitchd log file indicates that a feature is not
supported, consider upgrading to a newer upstream Linux release or using
the kernel module paired with the userspace distribution.
Q: Why do tunnels not work when using a kernel module other than the one
packaged with Open vSwitch?
A: Support for tunnels was added to the upstream Linux kernel module after
the rest of Open vSwitch. As a result, some kernels may contain support for
Open vSwitch but not tunnels. The minimum kernel version that supports each
tunnel protocol is:
======== ============
Protocol Linux Kernel
======== ============
GRE 3.11
VXLAN 3.12
Geneve 3.18
LISP not upstream
STT not upstream
======== ============
If you are using a version of the kernel that is older than the one listed
above, it is still possible to use that tunnel protocol. However, you must
compile and install the kernel module included with the Open vSwitch
distribution rather than the one on your machine. If problems persist after
doing this, check to make sure that the module that is loaded is the one
you expect.
Q: Why are UDP tunnel checksums not computed for VXLAN or Geneve?
A: Generating outer UDP checksums requires kernel support that was not part
of the initial implementation of these protocols. If using the upstream
Linux Open vSwitch module, you must use kernel 4.0 or newer. The
out-of-tree modules from Open vSwitch release 2.4 and later support UDP
checksums.
Q: What features are not available when using the userspace datapath?
A: Tunnel virtual ports are not supported, as described in the previous
answer. It is also not possible to use queue-related actions. On Linux
kernels before 2.6.39, maximum-sized VLAN packets may not be transmitted.
Q: Should userspace or kernel be upgraded first to minimize downtime?
A. In general, the Open vSwitch userspace should be used with the kernel
version included in the same release or with the version from upstream
Linux. However, when upgrading between two releases of Open vSwitch it is
best to migrate userspace first to reduce the possibility of
incompatibilities.
Q: What happened to the bridge compatibility feature?
A: Bridge compatibility was a feature of Open vSwitch 1.9 and earlier.
When it was enabled, Open vSwitch imitated the interface of the Linux
kernel "bridge" module. This allowed users to drop Open vSwitch into
environments designed to use the Linux kernel bridge module without
adapting the environment to use Open vSwitch.
Open vSwitch 1.10 and later do not support bridge compatibility. The
feature was dropped because version 1.10 adopted a new internal
architecture that made bridge compatibility difficult to maintain. Now
that many environments use OVS directly, it would be rarely useful in any
case.
To use bridge compatibility, install OVS 1.9 or earlier, including the
accompanying kernel modules (both the main and bridge compatibility
modules), following the instructions that come with the release. Be sure
to start the ovs-brcompatd daemon.
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