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VLC DASH Tutorial using OpenFlow LoadBalancer

In this tutorial, we will show how to run VLC DASH using OpenFlow on GENI. Dynamic Adaptive Streaming over HTTP (DASH) is used to adapt the quality of the video based on the bandwidth between the video streaming server and the client.

This exercise builds on the OpenFlow Load Balancer Tutorial that can be found here.


This tutorial leverages resources on the GENI aggregate in order to experiment with VLC DASH. For this tutorial, you will install an Apache server with videos that have already been encoded in a DASH format on one node and install an OMLified VLC client on another node. You will then be able to run the load-balancer using OpenFlow and OVS switches and subsequently use LabWiki to observe how the quality of the video changes based on available bandwidth between the server and the client.



1. Trema
Each exercise in this assignment will require you to design and implement an OpenFlow controller. Numerous libraries and controller frameworks are available for this task. The guidelines in this assignment assume that you are using the Trema controller framework. The Trema project web site,, contains documentation, a number of helpful examples, and some tutorial material for learning to use Trema.

2. Traffic Control (tc)
The tc command is available in the GNU Linux distributions on GENI nodes, found in the /sbin directory. This command manipulates the Linux network forwarding tables, allowing for configuration of queuing disciplines, which change the policies controlling which packets are forwarded in what order and which are dropped; and network emulation, which allows the Linux kernel to emulate various network conditions such as delay or loss. These two effects are provided by the qdisc and netem subcommands, respectively. In these exercises, tc will be used to modify network conditions and enable different scheduling policies. Example command lines will be provided.

3. Iperf
Iperf is available on the GENI nodes, located at /usr/local/etc/emulab/emulab-iperf. Iperf is used to measure the bandwidth performance of Internet links. In these exercises, it is used to study the behavior of TCP in the face of changing link characteristics. Iperf runs as both a server and a client. The server is started with the -s command line option, and listens for connections from the client. The client is started with the -c <server> command line option, and connects to the server and sends data at either the fastest possible rate (given the underlying network) or a user-specified rate. The -u option causes the sender or receiver to use UDP instead of TCP. Various other options will be required for these exercises, and provided in the appropriate sections. All Iperf measurement data should be recorded from the TCP receiver (server) side.

How to get Help

  • Always ask your tutors (tutorial helper/presenter/TA) first. They are the fastest way to solve the problem.
  • If you are using a specific aggregate or tool, you should consider registering in their mailing list. It is a great way to get connected with other GENI users and it is an excellent source of wisdom.
  • Send mail to the GENI help list:
  • If you want to chat real-time with other GENI users and ask questions, join us in a GENI chatroom.

Tutorial Instructions

  • Part II: Execute
    • 2. Configure and Initialize services
    • 3. Run your experiment
    • Appendix: Hints and Explanations

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