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How to Install Open vSwitch on Linux, FreeBSD and NetBSD

This document describes how to build and install Open vSwitch on a generic Linux, FreeBSD, or NetBSD host. For specifics around installation on a specific platform, please see one of these files:

Build Requirements

To compile the userspace programs in the Open vSwitch distribution, you will need the following software:

  • GNU make.

  • A C compiler, such as:

    • GCC 4.x.

    • Clang. Clang 3.4 and later provide useful static semantic analysis and thread-safety checks. For Ubuntu, there are nightly built packages available on clang's website.

    While OVS may be compatible with other compilers, optimal support for atomic operations may be missing, making OVS very slow (see lib/ovs-atomic.h).

  • libssl, from OpenSSL, is optional but recommended if you plan to connect the Open vSwitch to an OpenFlow controller. libssl is required to establish confidentiality and authenticity in the connections from an Open vSwitch to an OpenFlow controller. If libssl is installed, then Open vSwitch will automatically build with support for it.

  • Python 2.x, for x >= 4.

On Linux, you may choose to compile the kernel module that comes with the Open vSwitch distribution or to use the kernel module built into the Linux kernel (version 3.3 or later). See the FAQ.md question "What features are not available in the Open vSwitch kernel datapath that ships as part of the upstream Linux kernel?" for more information on this trade-off. You may also use the userspace-only implementation, at some cost in features and performance (see INSTALL.userspace.md for details). To compile the kernel module on Linux, you must also install the following:

  • A supported Linux kernel version. Please refer to README.md for a list of supported versions.

    The Open vSwitch datapath requires bridging support (CONFIG_BRIDGE) to be built as a kernel module. (This is common in kernels provided by Linux distributions.) The bridge module must not be loaded or in use. If the bridge module is running (check with "lsmod | grep bridge"), you must remove it ("rmmod bridge") before starting the datapath.

    For optional support of ingress policing, you must enable kernel configuration options NET_CLS_BASIC, NET_SCH_INGRESS, and NET_ACT_POLICE, either built-in or as modules. (NET_CLS_POLICE is obsolete and not needed.)

    To use GRE tunneling on Linux 2.6.37 or newer, kernel support for GRE demultiplexing (CONFIG_NET_IPGRE_DEMUX) must be compiled in or available as a module. Also, on kernels before 3.11, the ip_gre module, for GRE tunnels over IP (NET_IPGRE), must not be loaded or compiled in.

    To configure HTB or HFSC quality of service with Open vSwitch, you must enable the respective configuration options.

    To use Open vSwitch support for TAP devices, you must enable CONFIG_TUN.

  • To build a kernel module, you need the same version of GCC that was used to build that kernel.

  • A kernel build directory corresponding to the Linux kernel image the module is to run on. Under Debian and Ubuntu, for example, each linux-image package containing a kernel binary has a corresponding linux-headers package with the required build infrastructure.

If you are working from a Git tree or snapshot (instead of from a distribution tarball), or if you modify the Open vSwitch build system or the database schema, you will also need the following software:

  • Autoconf version 2.63 or later.

  • Automake version 1.10 or later.

  • libtool version 2.4 or later. (Older versions might work too.)

To run the unit tests, you also need:

  • Perl. Version 5.10.1 is known to work. Earlier versions should also work.

The ovs-vswitchd.conf.db(5) manpage will include an E-R diagram, in formats other than plain text, only if you have the following:

  • "dot" from graphviz (http://www.graphviz.org/).

  • Perl. Version 5.10.1 is known to work. Earlier versions should also work.

  • Python 2.x, for x >= 4.

If you are going to extensively modify Open vSwitch, please consider installing the following to obtain better warnings:

Also, you may find the ovs-dev script found in utilities/ovs-dev.py useful.

Installation Requirements

The machine on which Open vSwitch is to be installed must have the following software:

  • libc compatible with the libc used for build.

  • libssl compatible with the libssl used for build, if OpenSSL was used for the build.

  • On Linux, the same kernel version configured as part of the build.

  • For optional support of ingress policing on Linux, the "tc" program from iproute2 (part of all major distributions and available at http://www.linux-foundation.org/en/Net:Iproute2).

On Linux you should ensure that /dev/urandom exists. To support TAP devices, you must also ensure that /dev/net/tun exists.

Building and Installing Open vSwitch for Linux, FreeBSD or NetBSD

Once you have installed all the prerequisites listed above in the Base Prerequisites section, follow the procedure below to build.

  1. If you pulled the sources directly from an Open vSwitch Git tree, run boot.sh in the top source directory:

    % ./boot.sh

  2. Configure the package by running the configure script. You can usually invoke configure without any arguments. For example:

    % ./configure

    By default all files are installed under /usr/local. If you want to install into, e.g., /usr and /var instead of /usr/local and /usr/local/var, add options as shown here:

    % ./configure --prefix=/usr --localstatedir=/var

    By default, static libraries are built and linked against. If you want to use shared libraries instead:

    % ./configure --enable-shared

    To use a specific C compiler for compiling Open vSwitch user programs, also specify it on the configure command line, like so:

    % ./configure CC=gcc-4.2

    To use 'clang' compiler:

    % ./configure CC=clang

    To build the Linux kernel module, so that you can run the kernel-based switch, pass the location of the kernel build directory on --with-linux. For example, to build for a running instance of Linux:

    % ./configure --with-linux=/lib/modules/uname -r/build

    If --with-linux requests building for an unsupported version of Linux, then "configure" will fail with an error message. Please refer to the FAQ.md for advice in that case.

    If you wish to build the kernel module for an architecture other than the architecture of the machine used for the build, you may specify the kernel architecture string using the KARCH variable when invoking the configure script. For example, to build for MIPS with Linux:

    % ./configure --with-linux=/path/to/linux KARCH=mips

    If you plan to do much Open vSwitch development, you might want to add --enable-Werror, which adds the -Werror option to the compiler command line, turning warnings into errors. That makes it impossible to miss warnings generated by the build.

    To build with gcov code coverage support, add --enable-coverage, e.g.:

    % ./configure --enable-coverage

    The configure script accepts a number of other options and honors additional environment variables. For a full list, invoke configure with the --help option.

    You can also run configure from a separate build directory. This is helpful if you want to build Open vSwitch in more than one way from a single source directory, e.g. to try out both GCC and Clang builds, or to build kernel modules for more than one Linux version. Here is an example:

    % mkdir _gcc && (cd _gcc && ../configure CC=gcc)
    % mkdir _clang && (cd _clang && ../configure CC=clang)

  3. Run GNU make in the build directory, e.g.:

    % make

    or if GNU make is installed as "gmake":

    % gmake

    If you used a separate build directory, run make or gmake from that directory, e.g.:

    % make -C _gcc
    % make -C _clang

    For improved warnings if you installed "sparse" (see "Prerequisites"), add C=1 to the command line.

  4. Consider running the testsuite. Refer to "Running the Testsuite" below, for instructions.

  5. Become root by running "su" or another program.

  6. Run "make install" to install the executables and manpages into the running system, by default under /usr/local.

  7. If you built kernel modules, you may install and load them, e.g.:

    % make modules_install
    % /sbin/modprobe openvswitch

    To verify that the modules have been loaded, run "/sbin/lsmod" and check that openvswitch is listed.

    If the modprobe operation fails, look at the last few kernel log messages (e.g. with dmesg | tail):

    • The message "openvswitch: exports duplicate symbol br_should_route_hook (owned by bridge)" means that the bridge module is loaded. Run /sbin/rmmod bridge to remove it.

      If /sbin/rmmod bridge fails with "ERROR: Module bridge does not exist in /proc/modules", then the bridge is compiled into the kernel, rather than as a module. Open vSwitch does not support this configuration (see "Build Requirements", above).

    • The message "openvswitch: exports duplicate symbol dp_ioctl_hook (owned by ofdatapath)" means that the ofdatapath module from the OpenFlow reference implementation is loaded. Run /sbin/rmmod ofdatapath to remove it. (You might have to delete any existing datapaths beforehand, using the "dpctl" program included with the OpenFlow reference implementation. "ovs-dpctl" will not work.)

    • Otherwise, the most likely problem is that Open vSwitch was built for a kernel different from the one into which you are trying to load it. Run modinfo on openvswitch.ko and on a module built for the running kernel, e.g.:

      % /sbin/modinfo openvswitch.ko
% /sbin/modinfo /lib/modules/`uname -r`/kernel/net/bridge/bridge.ko

      Compare the "vermagic" lines output by the two commands. If they differ, then Open vSwitch was built for the wrong kernel.

    • If you decide to report a bug or ask a question related to module loading, please include the output from the dmesg and modinfo commands mentioned above.

    There is an optional module parameter to openvswitch.ko called vlan_tso that enables TCP segmentation offload over VLANs on NICs that support it. Many drivers do not expose support for TSO on VLANs in a way that Open vSwitch can use but there is no way to detect whether this is the case. If you know that your particular driver can handle it (for example by testing sending large TCP packets over VLANs) then passing in a value of 1 may improve performance. Modules built for Linux kernels 2.6.37 and later, as well as specially patched versions of earlier kernels, do not need this and do not have this parameter. If you do not understand what this means or do not know if your driver will work, do not set this.

  8. Initialize the configuration database using ovsdb-tool, e.g.:

    % mkdir -p /usr/local/etc/openvswitch
    % ovsdb-tool create /usr/local/etc/openvswitch/conf.db vswitchd/vswitch.ovsschema

Startup

Before starting ovs-vswitchd itself, you need to start its configuration database, ovsdb-server. Each machine on which Open vSwitch is installed should run its own copy of ovsdb-server. Configure it to use the database you created during installation (as explained above), to listen on a Unix domain socket, to connect to any managers specified in the database itself, and to use the SSL configuration in the database:

  % ovsdb-server --remote=punix:/usr/local/var/run/openvswitch/db.sock \
                 --remote=db:Open_vSwitch,Open_vSwitch,manager_options \
                 --private-key=db:Open_vSwitch,SSL,private_key \
                 --certificate=db:Open_vSwitch,SSL,certificate \
                 --bootstrap-ca-cert=db:Open_vSwitch,SSL,ca_cert \
                 --pidfile --detach

(If you built Open vSwitch without SSL support, then omit --private-key, --certificate, and --bootstrap-ca-cert.)

Then initialize the database using ovs-vsctl. This is only necessary the first time after you create the database with ovsdb-tool (but running it at any time is harmless):

  % ovs-vsctl --no-wait init

Then start the main Open vSwitch daemon, telling it to connect to the same Unix domain socket:

  % ovs-vswitchd --pidfile --detach

Now you may use ovs-vsctl to set up bridges and other Open vSwitch features. For example, to create a bridge named br0 and add ports eth0 and vif1.0 to it:

  % ovs-vsctl add-br br0
  % ovs-vsctl add-port br0 eth0
  % ovs-vsctl add-port br0 vif1.0

Please refer to ovs-vsctl(8) for more details.

Upgrading

When you upgrade Open vSwitch from one version to another, you should also upgrade the database schema:

  1. Stop the Open vSwitch daemons, e.g.:

    % kill `cd /usr/local/var/run/openvswitch && cat ovsdb-server.pid ovs-vswitchd.pid`

  2. Install the new Open vSwitch release.

  3. Upgrade the database, in one of the following two ways:

    • If there is no important data in your database, then you may delete the database file and recreate it with ovsdb-tool, following the instructions under "Building and Installing Open vSwitch for Linux, FreeBSD or NetBSD".

    • If you want to preserve the contents of your database, back it up first, then use "ovsdb-tool convert" to upgrade it, e.g.:

      % ovsdb-tool convert /usr/local/etc/openvswitch/conf.db vswitchd/vswitch.ovsschema

  4. Start the Open vSwitch daemons as described under "Building and Installing Open vSwitch for Linux, FreeBSD or NetBSD" above.

Hot Upgrading

Upgrading Open vSwitch from one version to the next version with minimum disruption of traffic going through the system that is using that Open vSwitch needs some considerations:

  1. If the upgrade only involves upgrading the userspace utilities and daemons of Open vSwitch, make sure that the new userspace version is compatible with the previously loaded kernel module.

  2. An upgrade of userspace daemons means that they have to be restarted. Restarting the daemons means that the OpenFlow flows in the ovs-vswitchd daemon will be lost. One way to restore the flows is to let the controller re-populate it. Another way is to save the previous flows using a utility like ovs-ofctl and then re-add them after the restart. Restoring the old flows is accurate only if the new Open vSwitch interfaces retain the old 'ofport' values.

  3. When the new userspace daemons get restarted, they automatically flush the old flows setup in the kernel. This can be expensive if there are hundreds of new flows that are entering the kernel but userspace daemons are busy setting up new userspace flows from either the controller or an utility like ovs-ofctl. Open vSwitch database provides an option to solve this problem through the other_config:flow-restore-wait column of the Open_vSwitch table. Refer to the ovs-vswitchd.conf.db(5) manpage for details.

  4. If the upgrade also involves upgrading the kernel module, the old kernel module needs to be unloaded and the new kernel module should be loaded. This means that the kernel network devices belonging to Open vSwitch is recreated and the kernel flows are lost. The downtime of the traffic can be reduced if the userspace daemons are restarted immediately and the userspace flows are restored as soon as possible.

The ovs-ctl utility's "restart" function only restarts the userspace daemons, makes sure that the 'ofport' values remain consistent across restarts, restores userspace flows using the ovs-ofctl utility and also uses the other_config:flow-restore-wait column to keep the traffic downtime to the minimum. The ovs-ctl utility's "force-reload-kmod" function does all of the above, but also replaces the old kernel module with the new one. Open vSwitch startup scripts for Debian, XenServer and RHEL use ovs-ctl's functions and it is recommended that these functions be used for other software platforms too.

Testsuites

This section describe Open vSwitch's built-in support for various test suites. You must configure and build Open vSwitch (steps 1 through 3 in "Building and Installing Open vSwitch for Linux, FreeBSD or NetBSD" above) before you run the tests described here. You do not need to install Open vSwitch or to build or load the kernel module to run these test suites. You do not need supervisor privilege to run these test suites.

Self-Tests

Open vSwitch includes a suite of self-tests. Before you submit patches upstream, we advise that you run the tests and ensure that they pass. If you add new features to Open vSwitch, then adding tests for those features will ensure your features don't break as developers modify other areas of Open vSwitch.

Refer to "Testsuites" above for prerequisites.

To run all the unit tests in Open vSwitch, one at a time: make check This takes under 5 minutes on a modern desktop system.

To run all the unit tests in Open vSwitch, up to 8 in parallel: make check TESTSUITEFLAGS=-j8 This takes under a minute on a modern 4-core desktop system.

To see a list of all the available tests, run: make check TESTSUITEFLAGS=--list

To run only a subset of tests, e.g. test 123 and tests 477 through 484: make check TESTSUITEFLAGS='123 477-484' (Tests do not have inter-dependencies, so you may run any subset.)

To run tests matching a keyword, e.g. "ovsdb": make check TESTSUITEFLAGS='-k ovsdb'

To see a complete list of test options: make check TESTSUITEFLAGS=--help

The results of a testing run are reported in tests/testsuite.log. Please report test failures as bugs and include the testsuite.log in your report.

If you have "valgrind" installed, then you can also run the testsuite under valgrind by using "make check-valgrind" in place of "make check". All the same options are available via TESTSUITEFLAGS. When you do this, the "valgrind" results for test <N> are reported in files named tests/testsuite.dir/<N>/valgrind.*. You may find that the valgrind results are easier to interpret if you put "-q" in ~/.valgrindrc, since that reduces the amount of output.

Sometimes a few tests may fail on some runs but not others. This is usually a bug in the testsuite, not a bug in Open vSwitch itself. If you find that a test fails intermittently, please report it, since the developers may not have noticed.

OFTest

OFTest is an OpenFlow protocol testing suite. Open vSwitch includes a Makefile target to run OFTest with Open vSwitch in "dummy mode". In this mode of testing, no packets travel across physical or virtual networks. Instead, Unix domain sockets stand in as simulated networks. This simulation is imperfect, but it is much easier to set up, does not require extra physical or virtual hardware, and does not require supervisor privileges.

To run OFTest with Open vSwitch, first read and follow the instructions under "Testsuites" above. Second, obtain a copy of OFTest and install its prerequisites. You need a copy of OFTest that includes commit 406614846c5 (make ovs-dummy platform work again). This commit was merged into the OFTest repository on Feb 1, 2013, so any copy of OFTest more recent than that should work. Testing OVS in dummy mode does not require root privilege, so you may ignore that requirement.

Optionally, add the top-level OFTest directory (containing the "oft" program) to your $PATH. This slightly simplifies running OFTest later.

To run OFTest in dummy mode, run the following command from your Open vSwitch build directory: make check-oftest OFT=<oft-binary> where <oft-binary> is the absolute path to the "oft" program in OFTest.

If you added "oft" to your $PATH, you may omit the OFT variable assignment: make check-oftest By default, "check-oftest" passes "oft" just enough options to enable dummy mode. You can use OFTFLAGS to pass additional options. For example, to run just the basic.Echo test instead of all tests (the default) and enable verbose logging: make check-oftest OFT=<oft-binary> OFTFLAGS='--verbose -T basic.Echo'

If you use OFTest that does not include commit 4d1f3eb2c792 (oft: change default port to 6653), merged into the OFTest repository in October 2013, then you need to add an option to use the IETF-assigned controller port: make check-oftest OFT=<oft-binary> OFTFLAGS='--port=6653'

Please interpret OFTest results cautiously. Open vSwitch can fail a given test in OFTest for many reasons, including bugs in Open vSwitch, bugs in OFTest, bugs in the "dummy mode" integration, and differing interpretations of the OpenFlow standard and other standards.

Open vSwitch has not been validated against OFTest. Please do report test failures that you believe to represent bugs in Open vSwitch. Include the precise versions of Open vSwitch and OFTest in your bug report, plus any other information needed to reproduce the problem.

Ryu

Ryu is an OpenFlow controller written in Python that includes an extensive OpenFlow testsuite. Open vSwitch includes a Makefile target to run Ryu in "dummy mode". See "OFTest" above for an explanation of dummy mode.

To run Ryu tests with Open vSwitch, first read and follow the instructions under "Testsuites" above. Second, obtain a copy of Ryu, install its prerequisites, and build it. You do not need to install Ryu (some of the tests do not get installed, so it does not help).

To run Ryu tests, run the following command from your Open vSwitch build directory: make check-ryu RYUDIR=<ryu-source-dir> where <ryu-source-dir> is the absolute path to the root of the Ryu source distribution. The default <ryu-source-dir> is $srcdir/../ryu where $srcdir is your Open vSwitch source directory, so if this default is correct then you make simply run make check-ryu.

Open vSwitch has not been validated against Ryu. Please do report test failures that you believe to represent bugs in Open vSwitch. Include the precise versions of Open vSwitch and Ryu in your bug report, plus any other information needed to reproduce the problem.

Continuous Integration with Travis-CI

A .travis.yml file is provided to automatically build Open vSwitch with various build configurations and run the testsuite using travis-ci. Builds will be performed with gcc, sparse and clang with the -Werror compiler flag included, therefore the build will fail if a new warning has been introduced.

The CI build is triggered via git push (regardless of the specific branch) or pull request against any Open vSwitch GitHub repository that is linked to travis-ci.

Instructions to setup travis-ci for your GitHub repository:

  1. Go to http://travis-ci.org/ and sign in using your GitHub ID.

  2. Go to the "Repositories" tab and enable the ovs repository. You may disable builds for pushes or pull requests.

  3. In order to avoid forks sending build failures to the upstream mailing list, the notification email recipient is encrypted. If you want to receive email notification for build failures, replace the the encrypted string: 3.1) Install the travis-ci CLI (Requires ruby >=2.0): gem install travis 3.2) In your Open vSwitch repository: travis encrypt [email protected] 3.3) Add/replace the notifications section in .travis.yml and fill in the secure string as returned by travis encrypt:

      notifications:
    email:
      recipients:
        - secure: "....."

    (You may remove/omit the notifications section to fall back to default notification behaviour which is to send an email directly to the author and committer of the failing commit. Note that the email is only sent if the author/committer have commit rights for the particular GitHub repository).

  4. Pushing a commit to the repository which breaks the build or the testsuite will now trigger a email sent to [email protected]

Bug Reporting

Please report problems to [email protected].