One of Mininet’s key features is that it makes it very easy to create a complete virtual network including hosts, switches, links and OpenFlow controllers. By default, Mininet runs Open vSwitch in OpenFlow mode, which requires an OpenFlow controller.
As you probably know, Mininet comes with built-in Controller() classes to
support several controllers, including the OpenFlow reference controller
controller), Open vSwitch’s
and the now-deprecated NOX Classic.
You can easily choose which one you want when you invoke the
sudo mn --controller ref sudo mn --controller ovsc sudo mn --controller NOX,pyswitch
Each of the above examples uses a controller which turns your OVS switches into Ethernet bridges (aka learning switches.)
ovsc is easy to install but only supports 16 switches.
You can install the reference controller (patched to support many switches)
install.sh -f. (As of this writing, you can also install NOX
The manual way: using remote controllers
But what do you do if you want another controller like POX? Well, one
way is to start up POX (or Beacon, Floodlight, etc.) in another terminal
window and then use
sudo mn --controller remote,ip=127.0.0.1
If your controller is running locally, you can just use
sudo mn --controller remote
You might be asking: is there a way for Mininet to automatically start up my controller so that I don’t have to do it manually? The answer is, of course, yes!
The automatic way #1: using the command line
The latest Mininet
master branch allows you to change the command and
--controller ref to invoke another controller as
desired. For example, here’s how you could invoke POX:
sudo mn --controller ref,command='python pox.py',cdir=$HOME/pox,cargs='openflow.of_01 --port=%s forwarding.l2_learning'
Note the following options:
cdir: the directory to change to before invoking the controller
command: the command to start your controller
cargs: the controller’s arguments (including
%s for wherever the controller’s listening port should go)
The super automatic way #2: creating a custom
This is much easier than it sounds, and it has worked in Mininet since version 1.0!
Here is a custom class for POX’s l2_learning:
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With this class saved into
pox.py, you can now do the following:
sudo mn --custom pox.py --controller pox
Additionally you can use the custom class in your Mininet scripts
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Note that in this custom class we’ve simply changed
__init__, but in a more complicated example you might
wish to change the
stop() methods as