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Month: December 2014

Setting up OpenVswitch and Mininet 2.2 on Ubuntu 14.04

In this tutorial I’ll briefly describe how to perform a standard installation of Mininet. This tutorial should work on Ubuntu 14.04.

sudo apt-get update
sudo apt-get install -y git
git clone git://github.com/mininet/mininet
cd mininet
git checkout -b 2.2.0 2.2.0
util/install.sh -nfv

Do install.sh -h to explore additional options.

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Topology Discovery with Ryu

How can be openflow used to do topology discovery? Why would you want to do that?

You might be interest in doing topology discovery on your topology for multiple reasons such as applying custom forwarding strategies from a centralized global view of the network. You may want something simple like running spanning tree or you may want to run shortest path forwarding. OpenFlow gives you the power to do that or even harder things.

SDN controllers can capitalize on the centralized view of the network and perform all kinds of operations such as pre-computing and installing backup paths.*

In this tutorial I’ll briefly describe the topology discovery module of the RYU controller and guide you through the development of a very naive application to print the information of the network.

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Shortest Path forwarding with Openflow on RYU

So, Openflow doesn’t do shortest path forwarding? How can a network architecture NOT do shortest path forwarding? SDN is BS.

Yes, Openflow doesn’t do shortest path forwarding by itself, in fact, it doesn’t do anything by itself. Openflow is a tool that allows you to programmatically control your network devices.

However, it gives you the power to do it. In this post I’ll guide you through the development of a shortest-path forwarding network application using the RYU Controller and Openflow. Hopefully I’ll post a few thoughts on different forwarding schemes and Openflow.

For this tutorial, I’m assuming you are familiar with Openflow, Mininet and RYU. If you are not, go ahead and check this other posts. I’m using¬†RYU, which is an OpenFlow Controller written in python with support to OpenFlow 1.3. To know more about it visit their website

To install RYU you can easily do pip install ryu and BOOM! If it doesn’t work you can try using the Mininet installation script with the -y option.

The network application will be organized in three blocks:

  • topology discovery
  • network view construction
  • forwarding

For the topology discovery we’ll use a RYU module/library called topology. For network view construction we’ll use an awesome python graph library called networkX. For forwarding we’ll use OpenFlow.

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