Thierry pls do not delete this page
How to define and use multi-hop topologies¶
Prerequisite¶
Before going through this tutorial, you should:- know the basics of writing and running an experiment script
- have installed a disk image on the nodes of the testbed you are using (for example, "baseline.ndz").
Objective¶
In this tutorial, you will learn how to define and use multi-hop topologies in your experiments.
After installing an image on all the nodes of a testbed, three default topologies are generated. One of them (system:topo:active) lists all the nodes that were correctly imaged. It lists all those nodes on the testbed that are currently working and have the requested disk image.
In this tutorial, you will use this default active topology to create your own multi-hop topologies.
The Tutorial Experiment¶
This experiment is given in the tut_topo_2.rb script.
This file contains extensive comments that should help you understand the different steps involved in defining and using multi-hop topologies.
Since all nodes are more or less within each others' 802.11 radio range in the current testbeds, this experiment is using a MAC address filtering tool to force given nodes to ignore other ones, thus emulating a multi-hop connectivity map.
There are currently three filtering tools to choose from: iptable, ebtable, and mackill. Before running this tutorial script, you have to make sure that the particular tool that you selected is indeed installed on the experiment nodes.
You can find more detailed information on the available commands to define topologies here.
To run this example script, use the following command:
omf exec tut_topo_2.rb
The Results¶
Click here to see the experiment screen output. Click here to see the experiment log file.
You can also access the results of this particular experiment example in the SQlite database, using the experiment ID: "grid_2007_11_20_18_58_12" (please refer to the Analysing Results page for more information.
Finally, as explained in the tut_topo_2.rb script, you can optionally save a graph of your multi-hop topology into a file that should look like this (in .jpg and .dot displayed with a tool such as graphviz) .