this the manual for installation http://inet.omnetpp.org/doc/INET/inet-manual-draft.pdf

but is it important install ??

Hello Israa,

Following are the instructions for INET installation:

//Automatic Installation

Recent versions of the OMNeT++ IDE can download and install INET (the latest stable version) for you.

How does it work?

Open the OMNeT++ IDE (omnetpp)

Go to the workbench (dismiss the Welcome screen). The first time you do this, a prompt will ask if you want to install INET.

Keep the boxes checked and proceed.

If you skipped this step (opened the workbench but skipped installing INET), nothing is lost:

Go to Help -> Install Simulation Models.

A dialog will appear with the available simulation models. Currently only INET is listed there, simply select it and follow the prompts.

Both ways, the IDE will download, unzip, and automatically build INET from the sources.

Manual Installation

You’ll need manual installation if you downloaded an INET version other than the latest stable one, or you have cloned the INET git repository to the local filesystem. The only “tricky” part is how to import the project into the workspace.

Download the INET sources

Unpack it into the directory of your choice: tar xvfz inet-.tgz

Start the OMNeT++ IDE, and import the project via File -> Import -> Existing Projects to the Workspace. A project named INET should appear.

Build with Project -> Build, or hit Ctrl+B

Now you should be able to launch example simulations.

Please also read the INSTALLATION file in the INET sources, as it may contain additional information.// Source: https://inet.omnetpp.org/Installation.html

Installing INET is partially necessary as it is considered as the base framework to begin with. It contains useful examples that you can utilize for your simulation depending on the network you want to simulate.

Hope this helps.