A best effort service to comment code and learn about this lab.

1. Install network simulator $sudo apt install ns2

2. Download xgraph from http://www.xgraph.org/linux/index.html for appropriate Ubuntu on your machine.

3. Untar the downloaded file : $sudo tar -C /bin/xgraph/ -xvf xgraph_4.38_linux64.tar.gz
   
   NOTE:
   a. I have untarred this to my /bin/xgraph/ directory(of which the xgraph dir is once which Ive mkdir'd).You can choose to untar it to your desired location by replacing /bin/xgraph to your destination dir path.
   
   b. This untared dir has a bin dir which contains the xgraph executable which we need to add to .bashrc

4. Navigate to home using directory and open .bashrc file (.bashrc is a hidden file and hence may not show up in your file-explorer,either options->show hidden files or open it on VIM via the terminal).

5. Create Alias for the command , add the below line into bashrc file
   alias xgraph='path_to_the_untarred_dir/bin/xgraph'

6. Run the below command to reflect changes made to bashrc :
   $ source ~/.bashrc

7. Have fun with tcl.`