QualNet 5.0 Exercises: Chapter 2. Application Layer

Objective

The purpose of this exercise is to develop an appreciation for the client-server network application architecture in modern network applications. Moreover, it helps to gain further experience with QualNet GUI and to start using command line based QualNet.

Overview

First, you will configure and run Web applications over a wireless network of 30 nodes under QualNet GUI. Then, you will use command-line based QualNet to simulate above network applications again with provided configuration files.

Procedure

Part 1. Using GUI based QualNet

Create a new scenario named 'exp2' under the directory '[QUALNET_HOME]/scenarios/ user/' in the Scenario Designer (please refer related part in Chapter 1 exercise for details).
Place 30 nodes automatically in the network.
- From the Experiment pull down menu, select Place Nodes (If it's gray/disabled, double click the canvas/ScenarioDesigner).
- Within the Automatic Node Placement Wizard, input '30' as Number of Nodes.
- Click Next, choose 'Uniform' as Placement Strategy.
- Click Next, use '1' as Seed.
- Click Finish and the resulting canvas should look like the following.
Add a Web application with node 1 as the HTTP client and nodes 2, 5 and 11 as HTTP servers.
- In the Inspector, expand Hierarchy(0)->Nodes->host1, right click SingleHostApplications and choose Add.
- Within the Single Host Application Wizard, select HTTP
  and click Finish.
- Click Finish and there is a HTTP sign shown beside node 1 on the canvas.
- In the Inspector, expand host1's SingleHostApplications to modify HTTP properties. Set Start Time as '10S', Threshold Time as '120S', and List of Servers as '2 5 11'. This means the HTTP client on node 1 chooses among HTTP servers {2, 5, 11} when requesting web pages. It begins browsing after 10 seconds of simulation time, and will "think" (remain idle) for at most 2 minutes at a time.
Set simulation time to 15 minutes by modifying corresponding property of General after expanding ConfigSettings->General in the Inspector.
Choose 'AODV' as Routing Protocol under ConfigSettings->Network Protocols->Routing Protocol->Routing Policy->Routing Protocol in the Inspector.
Run scenario in the Animator (refer related part in Chapter 1 exercise for details).
Review Application statistics in the Analyzer (refer related part in Chapter 1 exercise for details).
Go back Scenario Designer to add another Web application with node 15 as the HTTP client and nodes 2, 5 and 8 as HTTP servers, similarly to step 3.
Run the modified scenario.
Check Application statistics in the Analyzer again.

Part 2. Using command line based QualNet

Download the configuration files (exp2a.config, exp2a.app, exp2b.config, exp2b.app) here. Browse and try understanding the main idea of each file, especially the app files (for detailed description, refer corresponding default files with the same suffix under the directory '[QUALNET_HOME]/scenarios/default/'). Place the four downloaded files in the directory '[QUALNET_HOME]/bin/'.
Experiment 2a: Under above directory, type 'qualnet exp2a.config' to run QualNet command line with the application file exp2a.app, which defines the same Web application with one HTTP client and three HTTP servers, as in step 3 of Part 1. The statistics file this experiment produces is exp2a.stat.
Experiment 2b: Similarly, type 'qualnet exp2b.config' in command line to run QualNet with the application file exp2b.app, which simulates the same HTTP traffic with two HTTP clients and four HTTP servers, as in step 8 of Part 1. The statistics file this experiment produces is exp2b.stat.

Questions

What transport layer protocol is used to support the Web application, TCP or UDP?
In the application file exp2b.app, what are the HTTP clients and servers?
Compare collected statistics files exp2a.stat and exp2b.stat in experiments 2a and 2b. What is the time used by each HTTP server to send data in experiments 2a and 2b?
Examine statistics Connection Length(s) reported in exp2a.stat and exp2b.stat. What is the relationship between the client's and server's reported connection lengths?

References and Further Readings

Section 2.1 and 2.2 of the textbook.
QualNet 5.0 User's Guide.