Internet Technologies and Applications (ITS 413)

Assignment 1

Format:

Group project, 2 or 3 students per group

Weight:

25% of course score

Deadline:

23:59 Wednesday 28 March 2012

Late assignments:

-10% per hour

Overview and Requirements

This assignment involves learning about wireless LANs and transport protocol performance. You will be required to configure a small wireless LAN and run experiments that evaluate the performance of the wireless LAN against a wired Ethernet, especially when using UDP and TCP transport protocols. In addition to learning about networks and network performance, you will learn how to setup and report on network experiments.

The assignment will be run across several phases. You will be required to complete each phase by a deadline. You will also receive feedback after each phase.

Your group will be supplied with a wireless LAN access point. You are required to use your own laptop computers for wireless LAN clients. Two laptops per group should be sufficient. If you don't have access to two laptops then you can use lab computers at SIIT. Let me know if you have problems getting regular access to a computer.

Phase 1: Configure a Wireless LAN

Due Date: 13:30 Wednesday 1 Feb 2012

Your aim is to setup a small wireless LAN of a single AP (supplied) and two clients (your laptops). This will give you the opportunity to learn about the different wireless LAN parameters available to the end-user. To allow for experiments in subsequent phases you will used OpenWRT on the AP.

Your tasks are:

1. Install OpenWRT on the supplied Linksys WRT54GL wireless LAN AP. Use version Backfire 10.03.1 with the Broadcom Linux 2.4 kernel, i.e. this firmware image. Set the hostname to your group ID and the password to its413
2. Enable and test the wireless LAN. Set the ESSID to your group ID.
3. Explore the different parameters available to the user in OpenWRT, especially for configuring the wireless LAN.

Deliverables: You need to demonstrate your wireless LAN in class (e.g. I should be able to associate and transfer data via the wireless LAN, as well as login to the AP). There is no written deliverable (this phase is primarily for you to setup the AP and learn the OpenWRT interfaces).

Phase 2: Determine peak throughput of Wireless LAN and Ethernet

Due Date: 17:00 Thursday 15 Feb 2012

Phase 2 reports, with comments, are available for download, as are the marks for phase 2.

Your aim is to measure the maximum throughput that can be achieved over a wireless LAN and Ethernet link.

Your tasks are:

1. Using the default OpenWRT parameters, use iperf to measure the UDP throughput over each link (wireless LAN and Ethernet) with different sending rates (i.e. increasing the sending rate until you finally determine the maximum possible throughput).
2. Write a draft report on the experiments conducted so far.

Deliverables: You need to submit the draft report for evaluation (template in DOCX or PDF. You will receive a score (worth 5%) and feedback on the draft. Your draft will also be made available to the other groups, so they can see different examples and feedback.

Some further information on the tools and measurements include (note some of the hints below are not relevant for this phase, but may be for phase 3, i.e. you don't need tc in phase 2):

• Using iperf to Measure Application Throughput in the Internet, a video demonstrating iperf on the command line
• Quick Start Guide for iperf and tc
• Dropping Packets in Ubuntu Linux using tc and iptables
• Some parts of this assignment are similar to previous years. Hence comments I provided on the ITS413 Mailing List may provide useful information. But beware, some parts of the assignments have changed, so not everything is relevant. Some specific posts include:
  • Installing iperf and tc on Ubuntu
  • Reporting results from iperf server or client
  • What the options in iperf mean
  • iperf and other software on Mac OS
  • Reporting results from iperf
  • What not to submit
  • Why use iperf command line (instead of jperf)?
  • Further hints on iperf
  • iperf and the length option
  • TCP and bandwidth delay product

Phase 3: Performance Analysis of Transport Protocols over Wireless LAN and Ethernet

Due Date: 23:59 Wednesday 28 Mar 2012

Your aim is to determine how different parameters and scenarios impact on the performance of transport protocols (TCP and UDP) in a wireless LAN and Ethernet link.

Your tasks are:

1. Design a set of experiments that will most likely demonstrate the main factors that impact on throughput in a wireless LAN and/or Ethernet. Suggest experiments are listed below. (The links are some extra explanations and hints about how to conduct each experiment; they mainly come from notes and the email archive).
   • TCP vs UDP
   • TCP over wireless vs wired
   • Impact of packet drops on TCP performance (dropping packets with iptables)
   • Impact of window sizes on TCP performance (explanation of iperf options)
   • TCP and the bandwidth delay product (detailed experiment setup, email discussion)
   • Impact of different congestion control algorithms on TCP (how to change congestion control algorithm in Linux
   • Multiple TCP sessions
   • TCP and UDP sessions
   • TCP sessions over varying durations
2. Conduct the experiments.
3. Write a final report on all experiments (including from phase 2).

Deliverables: You need to submit the final report for evaluation. You will receive a score (worth 20%) and feedback. This is the final report and there is no opportunity for re-submission.

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