Open vSwitch 1.9.0 on Red Hat Enterprise Linux (RHEL) 6.4

I’ve been using Open vSwitch as a replacement for the stock bridge module in Linux for a few months now.

Open vSwitch is basically a open source virtual switch for Linux. It gives you much greater flexibility than the stock bridge module, effectively turning it into a managed, virtual layer 2 switch.

Open vSwitch has a very long list of features, but I chose to use it instead of the stock bridging module because Open vSwitch offers much greater flexibility with VLANing on Virtual Machines than what is possible with the stock Linux bridge module.

As my KVM servers are running an older version of Open vSwitch (1.4.6), I decided to upgrade to the latest version, which is 1.9.0 at time of writing this post.

RedHat actually provide RPMs for Open vSwitch as part of a tech preview in the Red Hat OpenStack Folsom Preview repository. They also include the Open vSwitch kernel module in their kernel, but they are using version 1.7.1, I wanted 1.9.0, so I decided to write this blog post.

EDIT: 10/04/2013 – Looking closer, it looks like RedHat also have an RPM for 1.9.0, but they do not include the brcompat module. If you need this module, then you’ll have to build your own RPMs.

RedHat have actually back-ported a number of functions from newer kernels into the kernel provided with RHEL. This causes a problem when compiling the Open vSwitch kernel module as the OVS guys have also back-ported those functions and were using kernel version checks to apply those backports.

The OVS guys have pushed a patch into the OVS git repo which fixes this problem, so I won’t be using the tarball provided on the OVS site, but rather building from the OVS 1.9 branch of the git repository.

When using the git version of Open vSwitch, we need to run the bootstrap script to create the configure script etc, but this requires a newer version of autoconf. You can either compile autoconf yourself, or I’m sure someone has create a RHEL6 RPM for a newer version of autoconf somewhere, but I just done this part on a Fedora machine instead as it was easier:
git clone git://openvswitch.org/openvswitch
git checkout -b branch-1.9 origin/branch-1.9
./boot.sh
./configure
make dist

Now you’ll have a shiny new tarball: openvswitch-1.9.1.tar.gz

I moved this over to my dedicated RPM building virtual machine and extracted it:
tar -xf openvswitch-1.9.1.tar.gz
cd openvswitch-1.9.1

I got a compilation error when trying to build the Open vSwitch tools inside mock as openssl-devel isn’t listed as a requirement in the spec file so mock doesn’t pull it in. It’s an easy fix, I edited the spec file and added openssl/openssl-devel to it:
--- openvswitch.spec.orig 2013-04-01 18:43:50.337000000 +0100
+++ openvswitch.spec 2013-04-01 18:44:10.612000000 +0100
@@ -19,7 +19,8 @@ License: ASL 2.0
Release: 1
Source: openvswitch-%{version}.tar.gz
Buildroot: /tmp/openvswitch-rpm
-Requires: openvswitch-kmod, logrotate, python
+Requires: openvswitch-kmod, logrotate, python, openssl
+BuildRequires: openssl-devel

%description
Open vSwitch provides standard network bridging functions and

Next, I created the SRPMs using mock:

mock -r epel-6-x86_64 --sources ../ --spec rhel/openvswitch.spec --buildsrpm
mv /var/lib/mock/epel-6-x86_64/result/*.rpm ./


mock -r epel-6-x86_64 --sources ../ --spec rhel/openvswitch-kmod-rhel6.spec --buildsrpm
mv /var/lib/mock/epel-6-x86_64/result/*.rpm ./

Then, actually build the RPMs:

mkdir ~/openvswitch-rpms/

mock -r epel-6-x86_64 --rebuild openvswitch-1.9.1-1.src.rpm
mv /var/lib/mock/epel-6-x86_64/result/*.rpm ~/openvswitch-rpms/

mock -r epel-6-x86_64 --rebuild openvswitch-kmod-1.9.1-1.el6.src.rpm
mv /var/lib/mock/epel-6-x86_64/result/*.rpm ~/openvswitch-rpms/

All done! Next either sign and dump the freshly built RPMs from ~/openvswitch-rpms/ into into your yum repository, or scp them over to each host you will be installing them on, and use yum to install:
yum localinstall openvswitch-1.9.1-1.x86_64.rpm kmod-openvswitch-1.9.1-1.el6.x86_64.rpm

I won’t go into configuration of Open vSwitch in this post, but it’s not too difficult, and there are many posts elsewhere that go into this.