OVN on Linux, FreeBSD and NetBSD

This document describes how to build and install OVN on a generic Linux, FreeBSD, or NetBSD host. For specifics around installation on a specific platform, refer to one of the other installation guides listed in Installing Open Virtual Network (OVN).

Obtaining OVN Sources

The canonical location for OVN source code is its Git repository, which you can clone into a directory named “ovn” with:

$ git clone https://github.com/ovn-org/ovn.git

Cloning the repository leaves the “master” branch initially checked out. This is the right branch for general development. If, on the other hand, if you want to build a particular released version, you can check it out by running a command such as the following from the “ovn” directory:

$ git checkout v20.09.0

The repository also has a branch for each release series. For example, to obtain the latest fixes in the OVN 20.09.x release series, which might include bug fixes that have not yet been in any released version, you can check it out from the “ovn” directory with:

$ git checkout origin/branch-20.09

If you do not want to use Git, you can also obtain tarballs for OVN release versions <https://www.ovn.org/en/releases/>, or download a ZIP file for any snapshot from the GitHub web interface <https://github.com/ovn-org/ovn>.

Build Requirements

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

  • Open vSwitch (https://docs.openvswitch.org/en/latest/intro/install/).
  • GNU make
  • One of the following C compilers:
    • GCC 4.6 or later.
    • Clang 3.4 or later.
    • MSVC 2013. Refer to OVN on Windows for additional Windows build instructions.
  • libssl, from OpenSSL, is optional but recommended if you plan to connect the OVN services to the OVN DB ovsdb-servers securely. If libssl is installed, then OVN will automatically build with support for it.
  • Unbound library, from http://www.unbound.net, is optional but recommended if you want to enable ovn-northd, ovn-controller and other utilities to use DNS names when specifying OVSDB remotes. If unbound library is already installed, then OVN will automatically build with support for it. The environment variable OVS_RESOLV_CONF can be used to specify DNS server configuration file (the default file on Linux is /etc/resolv.conf).

If you are working from a Git tree or snapshot (instead of from a distribution tarball), or if you modify the OVN 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.)

The OVN manpages will include an E-R diagram, in formats other than plain text, only if you have the following:

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

  • “sparse” version 0.5.1 or later (https://git.kernel.org/pub/scm/devel/sparse/sparse.git/).
  • GNU make.
  • clang, version 3.4 or later
  • flake8 along with the hacking flake8 plugin (for Python code). The automatic flake8 check that runs against Python code has some warnings enabled that come from the “hacking” flake8 plugin. If it’s not installed, the warnings just won’t occur until it’s run on a system with “hacking” installed.

You may find the ovs-dev script found in ovs/utilities/ovs-dev.py useful.

Installation Requirements

The machine you build OVN on may not be the one you run it on. To simply install and run OVN you require the following software:

  • Shared libraries compatible with those used for the build.

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


This step is not needed if you have downloaded a released tarball. If you pulled the sources directly from an Open vSwitch Git tree or got a Git tree snapshot, then run boot.sh in the top source directory to build the “configure” script:

$ ./boot.sh

Before configuring OVN, clone, configure and build Open vSwitch.


Configure the package by running the configure script. You need to invoke configure with atleast the argument –with-ovs-source. For example:

$ ./configure --with-ovs-source=/path/to/ovs/source

If you have built Open vSwitch in a separate directory, then you need to provide that path in the option - –with-ovs-build.

By default all files are installed under /usr/local. OVN expects to find its database in /usr/local/etc/ovn by default. If you want to install all files into, e.g., /usr and /var instead of /usr/local and /usr/local/var and expect to use /etc/ovn as the default database directory, add options as shown here:

$ ./configure --prefix=/usr --localstatedir=/var --sysconfdir=/etc


OVN installed with packages like .rpm (e.g. via yum install or rpm -ivh) and .deb (e.g. via apt-get install or dpkg -i) use the above configure options.

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 supply special flags to the C compiler, specify them as CFLAGS on the configure command line. If you want the default CFLAGS, which include -g to build debug symbols and -O2 to enable optimizations, you must include them yourself. For example, to build with the default CFLAGS plus -mssse3, you might run configure as follows:

$ ./configure CFLAGS="-g -O2 -mssse3"

For efficient hash computation special flags can be passed to leverage built-in intrinsics. For example on X86_64 with SSE4.2 instruction set support, CRC32 intrinsics can be used by passing -msse4.2:

$ ./configure CFLAGS="-g -O2 -msse4.2"`

Also builtin popcnt instruction can be used to speedup the counting of the bits set in an integer. For example on X86_64 with POPCNT support, it can be enabled by passing -mpopcnt:

$ ./configure CFLAGS="-g -O2 -mpopcnt"`

If you are on a different processor and don’t know what flags to choose, it is recommended to use -march=native settings:

$ ./configure CFLAGS="-g -O2 -march=native"

With this, GCC will detect the processor and automatically set appropriate flags for it. This should not be used if you are compiling OVS outside the target machine.


CFLAGS are not applied when building the Linux kernel module. Custom CFLAGS for the kernel module are supplied using the EXTRA_CFLAGS variable when running make. For example:

$ make EXTRA_CFLAGS="-Wno-error=date-time"

If you are a developer and want to enable Address Sanitizer for debugging purposes, at about a 2x runtime cost, you can add -fsanitize=address -fno-omit-frame-pointer -fno-common to CFLAGS. For example:

$ ./configure CFLAGS="-g -O2 -fsanitize=address -fno-omit-frame-pointer -fno-common"

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. Refer to the Open Virtual Network (OVN) FAQ for advice in that case.

If you plan to do much OVN 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. For example:

$ ./configure --enable-Werror

If you’re building with GCC, then, for improved warnings, install sparse (see “Prerequisites”) and enable it for the build by adding --enable-sparse. Use this with --enable-Werror to avoid missing both compiler and sparse warnings, e.g.:

$ ./configure --enable-Werror --enable-sparse

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

$ ./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:

$ ./configure --help

You can also run configure from a separate build directory. This is helpful if you want to build OVN in more than one way from a single source directory, e.g. to try out both GCC and Clang builds. For example:

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

Under certain loads the ovsdb-server and other components perform better when using the jemalloc memory allocator, instead of the glibc memory allocator. If you wish to link with jemalloc add it to LIBS:

$ ./configure LIBS=-ljemalloc
Example usage::

$ # Clone OVS repo $cd /home/foo/ovs $./boot.sh $mkdir _gcc $cd _gcc && ../configure && cd .. $make -C _gcc

$ # Clone OVN repo $cd /home/foo/ovn $./boot.sh $./configure –with-ovs-source=/home/foo/ovs/ –with-ovs-build=/home/foo/ovs/_gcc

It is expected to configure both Open vSwitch and OVN with the same prefix.


  1. 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


    Some versions of Clang and ccache are not completely compatible. If you see unusual warnings when you use both together, consider disabling ccache.

  2. Consider running the testsuite. Refer to Testing for instructions.

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

    $ make install


Before starting the OVN, start the Open vSwitch daemons. Refer to the Open vSwitch documentation for more details on how to start OVS.

On Unix-alike systems, such as BSDs and Linux, starting the OVN suite of daemons is a simple process. OVN includes a shell script, called ovn-ctl which automates much of the tasks for starting and stopping ovn-northd, ovn-controller and ovsdb-servers. After installation, the daemons can be started by using the ovn-ctl utility. This will take care to setup initial conditions, and start the daemons in the correct order. The ovn-ctl utility is located in ‘$(pkgdatadir)/scripts’, and defaults to ‘/usr/local/share/ovn/scripts’. ovn-ctl utility requires the ‘ovs-lib’ helper shell script which is present in ‘/usr/local/share/openvswitch/scripts’. So invoking ovn-ctl as “./ovn-ctl” will fail.

An example after install might be:

$ export PATH=$PATH:/usr/local/share/ovn/scripts
$ ovn-ctl start_northd
$ ovn-ctl start_controller

Starting OVN Central services

OVN central services includes ovn-northd, Northbound and Southbound ovsdb-server.

$ export PATH=$PATH:/usr/local/share/ovn/scripts $ ovn-ctl start_northd

Refer to ovn-ctl(8) for more information and the supported options.

You may wish to manually start the OVN central daemons. Before starting ovn-northd you need to start OVN Northbound and Southbound ovsdb-servers. Before ovsdb-servers can be started, configure the Northbound and Southbound databases:

$ mkdir -p /usr/local/etc/ovn
$ ovsdb-tool create /usr/local/etc/ovn/ovnnb_db.db \
$ ovsdb-tool create /usr/local/etc/ovn/ovnsb_db.db \

Configure ovsdb-servers to use databases created above, to listen on a Unix domain socket and to use the SSL configuration in the database:

$ mkdir -p /usr/local/var/run/ovn
$ ovsdb-server --remote=punix:/usr/local/var/run/ovn/ovnnb_db.sock \
     --remote=db:OVN_Northbound,NB_Global,connections \
     --private-key=db:OVN_Northbound,SSL,private_key \
     --certificate=db:OVN_Northbound,SSL,certificate \
     --bootstrap-ca-cert=db:OVN_Northbound,SSL,ca_cert \
     --pidfile --detach --log-file
$ovsdb-server --remote=punix:/usr/local/var/run/ovn/ovnsb_db.sock \
     --remote=db:OVN_Southbound,SB_Global,connections \
     --private-key=db:OVN_Southbound,SSL,private_key \
     --certificate=db:OVN_Southbound,SSL,certificate \
     --bootstrap-ca-cert=db:OVN_Southbound,SSL,ca_cert \
     --pidfile --detach --log-file


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

Initialize the databases using ovn-nbctl and ovn-sbctl. This is only necessary the first time after you create the databases with ovsdb-tool, though running it at any time is harmless:

$ ovn-nbctl --no-wait init
$ ovn-sbctl --no-wait init

Start the ovn-northd, telling it to connect to the OVN db servers same Unix domain socket:

$ ovn-northd --pidfile --detach --log-file

Starting OVN Central services in containers

For OVN central node, we dont need to load ovs kernel modules on host. Hence, OVN central containers OS need not depend on host OS.

Also we can leverage deploying entire OVN control plane in a pod spec for use cases like OVN-kubernetes

Export following variables in .env and place it under project root:


To build ovn modules:

$ cd utilities/docker
$ make build

Compiled Modules will be tagged with docker image

To Push ovn modules:

$ make push

OVN docker image will be pushed to specified docker repo.

Start OVN containers using below command:

$ docker run -itd --net=host --name=ovn-nb \
  <docker_repo>:<tag> ovn-nb-tcp

$ docker run -itd --net=host --name=ovn-sb \
  <docker_repo>:<tag> ovn-sb-tcp

$ docker run -itd --net=host --name=ovn-northd \
  <docker_repo>:<tag> ovn-northd-tcp

Start OVN containers in cluster mode for a 3 node cluster using below command on node1:

$ docker run -e "host_ip=<host_ip>" -e "nb_db_port=<port>" -itd \
  --name=ovn-nb-raft --net=host --privileged <docker_repo>:<tag> \

$ docker run -e "host_ip=<host_ip>" -e "sb_db_port=<port>" -itd \
  --name=ovn-sb-raft --net=host --privileged <docker_repo>:<tag> \

$ docker run -e "OVN_NB_DB=tcp:<node1>:6641,tcp:<node2>:6641,\
  tcp:<node3>:6641" -e "OVN_SB_DB=tcp:<node1>:6642,tcp:<node2>:6642,\
  tcp:<node3>:6642" -itd --name=ovn-northd-raft <docker_repo>:<tag> \

Start OVN containers in cluster mode using below command on node2 and node3 to make them join the peer using below command:

$ docker run -e "host_ip=<host_ip>" -e "remote_host=<remote_host_ip>" \
  -e "nb_db_port=<port>" -itd --name=ovn-nb-raft --net=host \
  --privileged <docker_repo>:<tag> ovn-nb-cluster-join

$ docker run -e "host_ip=<host_ip>" -e "remote_host=<remote_host_ip>" \
  -e "sb_db_port=<port>" -itd --name=ovn-sb-raft --net=host \
  --privileged <docker_repo>:<tag> ovn-sb-cluster-join

$ docker run -e "OVN_NB_DB=tcp:<node1>:6641,tcp:<node2>:6641,\
  tcp:<node3>:6641" -e "OVN_SB_DB=tcp:<node1>:6642,tcp:<node2>:6642,\
  tcp:<node3>:6642" -itd --name=ovn-northd-raft <docker_repo>:<tag> \

Start OVN containers using unix socket:

$ docker run -itd --net=host --name=ovn-nb \
  -v /var/run/ovn/:/var/run/ovn/ \
  <docker_repo>:<tag> ovn-nb

$ docker run -itd --net=host --name=ovn-sb \
  -v /var/run/ovn/:/var/run/ovn/
  <docker_repo>:<tag> ovn-sb

$ docker run -itd --net=host --name=ovn-northd \
  -v /var/run/ovn/:/var/run/ovn/
  <docker_repo>:<tag> ovn-northd


Current ovn central components comes up in docker image in a standalone and cluster mode with protocol tcp.

The debian docker file use ubuntu 16.04 as a base image for reference.

User can use any other base image for debian, e.g. u14.04, etc.

RHEL based docker support is now added with centos7 as a base image.

Starting OVN host service

On each chassis, ovn-controller service should be started. ovn-controller assumes it gets configuration information from the Open_vSwitch table of the local OVS instance. Refer to the ovn-controller(8) for the configuration keys.

Below are the required keys to be configured on each chassis.

  1. external_ids:system-id
  2. external_ids:ovn-remote
  3. external_ids:ovn-encap-type
  4. external_ids:ovn-encap-ip

You may wish to manually start the ovn-controller service on each chassis.

Start the ovn-controller, telling it to connect to the local ovsdb-server Unix domain socket:

$ ovn-controller --pidfile --detach --log-file

Starting OVN host service in containers

For OVN host too, we dont need to load ovs kernel modules on host. Hence, OVN host container OS need not depend on host OS.

Also we can leverage deploying OVN host in a pod spec for use cases like OVN-kubernetes to manage OVS which can be running as a service on host or in container.

Start ovsdb-server and ovs-vswitchd components as per http://docs.openvswitch.org/en/latest/intro/install/general/

start local ovn-controller with below command if ovs is also running in container:

$ docker run -itd --net=host --name=ovn-controller \
  --volumes-from=ovsdb-server \
  <docker_repo>:<tag> ovn-controller

start local ovn-controller with below command if ovs is running as a service:

$ docker run -itd --net=host --name=ovn-controller \
  -v /var/run/openvswitch/:/var/run/openvswitch/ \
  <docker_repo>:<tag> ovn-controller


At this point you can use ovn-nbctl on the central node to set up logical switches and ports and other OVN logical entities. For example, to create a logical switch sw0 and add logical port sw0-p1

$ ovn-nbctl ls-add sw0
$ ovn-nbctl lsp-add sw0 sw0-p1
$ ovn-nbctl show

Refer to ovn-nbctl(8) and ovn-sbctl (8) for more details.

When using ovn in container, exec to container to run above commands:

$ docker exec -it <ovn-nb/ovn-sb/ovn-northd/ovn-controller> /bin/bash

Reporting Bugs

Report problems to bugs@openvswitch.org.