Sunday, July 14, 2013

How to build an OpenFlow testbed on an Ubuntu 12.04 VM in VirtualBox

Installing Ubuntu

I started with an Ubuntu Server 12.04.2 64 bit iso, and a VirtualBox VM with 1024MB of RAM and 8GB of hard disk. My version of VirtualBox is 4.0.10r72479 on Windows 7 x64 Professional. The install is pretty normal - if you've never installed Ubuntu Server before, you shouldn't find this too hard - just follow the prompts and keep pressing enter.

This would be a good time to pour yourself a single malt coffee

Don't be too fussy about packages, but as a rule I tend to want to install the OpenSSH server just because it's a good habit to get into - and something that'll trip you up if you forget to just that one time when it's really important.

Pro tip ™

This will take a couple of minutes to finish, and then you'll have an Ubuntu install ready to go. Remember to eject the ISO, and then turn the machine off. Time for the ugly stuff.

Configuring the network stuff

I've set up my testbed with 3x Ubuntu servers, 2 of which were set up like this and left, and a third that we did some special stuff with. For all of them, we'll need to set up extra adaptors on Internal Networks - the two client machines each get a single new adaptor with their own intnet, and the OVS machine (the third one) gets two new adaptors - the first one goes onto intnet1 (to connect to client 1), and the second goes onto intnet2. I've left the original adaptor untouched on all of the machines so we can add packages later without having to break networking.

Edit our new OFSwitch2 VM

Keep Adapter 1 as is so we can download stuff

Intnet1 matches up with client VM 1

Intnet2 to client VM 2

Once you've set this up, find the vbox file for your VM and open it up in your text editor, Make sure you close VirtualBox first - otherwise it won't take your changes. You'll want to add the following lines:

<ExtraDataItem name="VBoxInternal/Devices/e1000/1/LUN#0/Config/IfPolicyPromisc" value="allow-all"/>
<ExtraDataItem name="VBoxInternal/Devices/e1000/2/LUN#0/Config/IfPolicyPromisc" value="allow-all"/>

The secret sauce

That last part is super important - I spend a few hours today and last night trying to figure out why some packets would hit the bridge and others wouldn't - VirtualBox by default will accept broadcasts and unicasts to your address, but not other MAC addresses. Being a switch, you generally want to accept every MAC address except your own, so this is fairly important.

Installing OpenVSwitch

I've used version 1.10 because it's the coolest. Download it to a folder on your VM, untar, and read the INSTALL file because that's what cool kids do. In actual fact, there's a INSTALL.Debian, but that didn't work for me, so I just built it the generic way.

Packages to install (so you don't spend the next hour chasing dependencies):

  • build-essential
  • pkg-config
  • autoconf
  • automake
  • python-qt-dev
  • python-dev
  • python-twisted-conch
  • libtool
Then run the install
sudo make install

I'm pleasantly surprised to say that this all worked the first time - just make sure you install all of those packages in one go and it'll work perfectly from the start :)

Running OpenVSwitch

Now is a good time to start up OpenVSwitch to test that everything is working as you should expect - if we do this right, then the OpenFlow part will be easy. Fire up your two client machines, and set up eth1 on both of them to IPs in the same range - I've used and, but use something else if this would clash with your other network.

Once you have them up, start up OpenVSwitch with the following stuff - I've kept them in separate screens to make it easier

Start a screen (screen)

Screen 0:
sudo modprobe openvswitch
sudo ovsdb-tool create

sudo ovsdb-server --remote=ptcp:9999:

New screen(CTRL+A, C)

Screen 1
sudo ovs-vswitchd tcp:

Screen 2
ovs-vsctl --db=tcp: add-br br0
ovs-vsctl --db=tcp: add-port br0 eth1
ovs-vsctl --db=tcp: add-port br0 eth2
ovs-vsctl --db=tcp: set bridge br0 protocols=OpenFlow12
sudo ifconfig eth1 up
sudo ifconfig eth2 up

If you bring up your client VMs you should be able to ping between them now. If you can, then great - we'll move onto getting OpenFlow working. You need one more line of code, assuming the controller is (or will be) on the same machine:

ovs-vsctl --db=tcp: set-controller br0 tcp:

Getting OpenFlow going

We're on the home straight here. You can install the controller of your choosing, or you can install Ryu with the following instructions:

sudo apt-get install git python-setuptools
git clone
cd ryu
sudo python install

You can then sit and watch as it downloads its dependencies from pypi. When it's done, fire up the controller with an app, and you're ready to go.

ryu-manager ryu/app/

You can check the flow tables (in another screen) with the following command:

sudo ovs-ofctl dump-flows br0

Check out the manpages if you want to learn more:

You've got an OpenFlow testbed now, you can do what you want with it. Play with different controllers, or different versions of OpenFlow - it's all up to you.

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