As you can see from the above figure that we have two hosts and
also both the hosts are connected to a
switch S
You can launch the above topology on the network by a command mentioned below
sudo mn

At this instant, you can see the command sudo mn creates
- Create a network
- Add controllers
- Adding two hosts
and
- Adding a switch
- As you can see from the above topology we need two links to connect
,
and
- Mininet is doing default configuration on hosts
and
- Mininet is starting a controller c0
- Mininet is starting a switch
- In the end, you will get a Mininet prompt where you can interact with the network
You can check the interfaces of the host by using the below command
h1 ifconfig -a
Similarly, you can also check interfaces of host by replacing
with
h2 ifconfig -a
You can ping host machine h1 to host machine h2 because there is a link is present in between them
h1 ping h2
Similarly, You can ping host machine h2 to host machine h1 because there is a link is present in between them
h2 ping h1
You can also ping h2 to h1 by using an IP address of h1
h2 ping 10.0.0.1
To exit the ping command use the short key Ctrl+c
To exit the current topology in the Mininet use the command mentioned below
exit
You can also view links information
links
To view the number of nodes in a topology
nodes
Shows even more info
dump
Shows the connectivity between nodes of the topology
net
Another example
As you can see, we have another Mininet topology to implement
so, you can launch the above topology by using the below command
sudo mn --topo=tree,depth=2,fanout=2
The above command shows that it will launch a tree base topology and depth=2 means the height of the tree will be two
Fanout =2 means the children that each node will have will be two
With the help of the above command, the mininet created a network topology by adding four hosts to the network

Finally, you can ping one host to another host in this network topology such
h1 ping h4
h1 ping h3
We can create even more customized or complex topologies by writing python programs and Mininet can execute these python programs to launch a topology
How to compile a python script with Mininet
If you like to create custom topologies with Mininet then you can use python scripts
So, to compile python scripts on Mininet first type the command mentioned below to check whether you have python ide
python
If you see something python versions such as python 3.8.5 or any other version that means you have a python ide

To exit from python-mode
Quit()
Note: that the commands that you use in the linux terminal are also applicable in the Mininet terminal
Let us create a folder for python scripts
mkdir Mininet_scripts
Get in the directory or folder Mininet_scripts
cd Mininet_scripts
Create a python file and edit it
Cat>simple_python_script.py
Type your python script
Print(“this is just a simple script to test”)
Save and exit the python program by a short key Ctrl+d
Compile the python script
Sudo python simple_python_script.py
If you like to edit the saved program then you can do it by using the below command
nano simple_python_script.py
To exit the nano command to use Ctrl+x
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