What is Mininet?

Mininet is a lightweight network emulator that creates a virtual network with hosts, switches, links, and controllers all on a single machine. It’s widely used in Software-Defined Networking (SDN) research and education.
mininet

Key Features

Lightweight and runs real code (like real Linux hosts)
Allows fast prototyping of large networks
Integrates well with OpenFlow and SDN controllers like POX, Ryu, and ONOS

Installation

mininet download

Basic Concepts

Host: virtual end device (eg, h1, h2)
Switch: OpenFlow-enabled switch (eg, s1)
Controller: Manages forwarding rules (eg, POX, Ryu)
Link: Virtual cable between nodes

Simple Command

Mininet Command Structure

Mininet commands fall into three categories:

Network Startup Parameters – —topo, —custom, —switch, —controller, —mac, etc.
Interactive CLI Commands – net, nodes, pingall, dump, iperf, etc.
External Parameters – -c (cleanup), -h (help), etc.

create simple topology

sudo mn

This launches the default topology (2 hosts, 1 switch, 1 controller)

Single Switch, Multiple Hosts

1	sudo mn --topo=single,5

Linear Topology (Switches connected in a line)

1 2	sudo mn --topo=linear,3 sudo mn --topo=linear,3,2

Tree Topology (Hierarchical switches)

1	sudo mn --topo=tree,depth=3,fanout=2

depth: Number of switch levels
fanout: Number of child switches/hosts per parent

list all nodes

nodes

show connections

net

test connectivity

pingall

show host IP

1	h1 ifconfig

test ping between hosts

1	h1 ping h2

exit & clean up

1	sudo mn -c

Custom Topology Example (Python Script)

from mininet.topo import Topo
from mininet.net import Mininet
from mininet.node import Controller
from mininet.cli import CLI
from mininet.link import TCLink

class MyTopo(Topo):
    def build(self):
        h1 = self.addHost('h1')
        h2 = self.addHost('h2')
        s1 = self.addSwitch('s1')
        self.addLink(h1, s1)
        self.addLink(h2, s1)

if __name__ == '__main__':
    topo = MyTopo()
    net = Mininet(topo=topo, controller=Controller)
    net.start()
    CLI(net)
    net.stop()