Lab 1: Switchyard & Mininet

Overview

In this chapter we will introduce all preparations for our network experiments. Then your are going to modify the examples we provide according to our requirements.

Details

Our lab assignments are based on CS640 in University of Wisconsin. Most materials are the same. In the future, we will improve the experiment based on your feedback.

In this lab assignment, you will gradually master our experimental environment. But some preliminary abilities are required in our experiments such as how to program and debug in Linux. If you are not familiar with these, feel free to contact TAs. We will provide you with some helpful information to get started quickly.

Platform

The platform of our labs is Switchyard. You can implement a device with various functions in Switchyard by writing Python codes. Then you can run your device in Mininet and capture packets using Wireshark. You will use Git to manage your projects and submit them. All these software are installed on Linux. We recommend using Visual Studio Code as your editor.

Here is the list of softwares we mentioned (sorted by learning order).

• Linux
• Python
• Git
• Mininet
• Wireshark
• Switchyard
• VS Code

Your Tasks

[!NOTE] The sentences marked with ✅ are related to the content of your report. Please pay attention.

Task 1: Get Ready

Meet the requirements for using Linux, Python and Git. We assume that you have a basic understanding of these contents.

Start your task here

Task 2: An Example

Meet the requirements for using Mininet, Wireshark and Switchyard. At the meantime you will learn how to complete this assignment.

Start your task here

Task 3: NJU GitLab

Sign up on NJU GitLab and prepare for submission.

Start your task here

[!DANGER] Do not skip this task. We use NJU GitLab to collect your projects.

Task 4: Your Modification

After Task 1 2 3, you are ready to do some exercises on our platform and count 4.

Start your task here

Handing it in

Report

We will provide a template of your lab assignment report here. You need to submit the report in your repository named <学号><姓名>_lab_1. The format of your report can be Microsoft Doc or PDF. An example is 123456789拾佰仟_lab_1.pdf.

Capture file

The capture file's name should be lab_1.pcapng or lab_1.pcap. If you capture packets using superuser, you may meet some problems. Read the tips below.

[!WARNING] You may (or as I expect you must) meet the error when you try to modify/delete the files generated by Wireshark or Switchyard programs running on hosts in Mininet. It is because the owner of these files is superuser root. You need to change the owner to your login user. Run the command below on your capture file. Replace <file> to the file path of your capture file.

$ sudo chown $USER:$USER <file>

Another useful command ls -l can check if the owner of the file is root. You can see the file belonging to root is test.log in the example.

(syenv) cyq@cyq-VirtualBox:~/switchyard$ ls -l
total 88
-rw-rw-r-- 1 cyq  cyq  35147 2月  20 17:33 COPYING
-rw-rw-r-- 1 cyq  cyq    427 2月  20 17:33 Dockerfile
drwxrwxr-x 6 cyq  cyq   4096 2月  20 17:33 docs
drwxrwxr-x 3 cyq  cyq   4096 2月  20 17:33 documentation
drwxrwxr-x 4 cyq  cyq   4096 2月  21 00:01 examples
-rw-rw-r-- 1 cyq  cyq   5119 2月  20 17:33 README.rst
-rw-rw-r-- 1 cyq  cyq    144 2月  20 17:33 requirements.txt
-rwxrwxr-x 1 cyq  cyq    405 2月  20 17:33 runtests.sh
-rw-rw-r-- 1 cyq  cyq   2266 2月  20 17:33 setup.py
drwxrwxr-x 4 cyq  cyq   4096 2月  20 17:33 switchyard
drwxrwxr-x 6 cyq  cyq   4096 2月  20 17:37 syenv
-rw-r--r-- 1 root root   181 2月  21 21:42 lab_1.pcap
drwxrwxr-x 2 cyq  cyq   4096 2月  20 17:33 tests

In this case, running the command sudo chown $USER:$USER ./lab_1.pcap can change the owner to my user cyq. As we mentioned before, be careful when using sudo since it may have potential risks.

Submit to NJU GitLab

When you are ready to submit, do the following.

1. Modify your code according to Task 3, complete your report and save your capture file.

2. When you have done your work, put your report, code and capture file in the folder lab_1 and commit them. Tag the commit named <学号/lab_1> which you want to submit. An example is 123456789/lab_1. For more about tag, read Git 基础 - 打标签. Finally your project will look like

   switchyard/
     ├─docs/
     ├─.../
   m ├─lab_1/
   + │ ├─123456789拾佰仟_lab_1.pdf
   m │ ├─hubtests.py
   + │ ├─lab_1.pcapng
   m │ ├─myhub.py
   m │ └─start_mininet.py
     ├─.gitignore
     └─...
   

   [!WARNING] The file names in your submission have to exactly match the file names above. Otherwise, you will lose points!

3. Submit your work by pushing your local repository to your remote repository with your tags by running the command git push origin --tags.

   [!WARNING] Only commit your source code to your local repository. If there are some generated files that are not source code, ignore them by adding them in the file .gitignore.