Question

In this assignment you will start with Python code that builds a 2 host network connected by a legacy router. You will modify it such that the two hosts can send packets to each other. It requires that you understand subnet addressing and the function of a router. The network built using Miniedit on a Mininet virtual machine: python mininet/examples/miniedit.py. We need to also make 6 static routes to make the program work.

This is the work that I have so far!!

#!/usr/bin/python
from mininet.net import Mininet
from mininet.node import Controller, RemoteController,OVSController
from mininet.node import Host, Node
from mininet.node import OVSKernelSwitch, UserSwitch
from mininet.node import IVSSwitch
from mininet.cli import CLI
from mininet.log import setLogLevel, info
from mininet.link import TCLink, Intf
from subprocess import call

def myNetwork():
net = Mininet( topo=None, build=False,ipBase='10.0.0.0/24')
info( '*** Adding controller\n' )
c0=net.addController(name='c0',controller=Controller, protocol='tcp',port=6633)

s1 = net.addSwitch('s1', cls=OVSKernelSwitch)
s2 = net.addSwitch('s2', cls=OVSKernelSwitch)

info( '*** Add switches\n')
r5 = net.addHost('r5', cls=Node, ip=' 10.0.1.1/24', defaultRoute='via 192.168.56.1')
r5.cmd('sysctl -w net.ipv4.ip_forward=1')
r4 = net.addHost('r4', cls=Node, ip=' 10.0.2.1/24', defaultRoute='via 192.168.56.2')
r4.cmd('sysctl -w net.ipv4.ip_forward=1')
r3 = net.addHost('r3', cls=Node, ip=' 10.0.3.1/24', defaultRoute='via 192.168.56.3')
r3.cmd('sysctl -w net.ipv4.ip_forward=1')

info( '*** Add hosts\n')
h1 = net.addHost('h1', cls=Host, ip='10.0.0.1',defaultRoute='via 10.0.3.1')
h2 = net.addHost('h2', cls=Host, ip='10.0.0.2',defaultRoute='via 10.0.1.1')

info( '*** Add links\n')
net.addLink(h1, s1)
net.addLink(h2, s2)
net.addLink(s2, r5, intfName2='r5-eth1', params2={ 'ip' : '10.0.1.1/24'})
net.addLink(s1, r3, intfName2='r3-eth1', params2={ 'ip' : '10.0.3.1/24'})
net.addLink(r3, r4, intfName1='r3-eth2', params1={ 'ip' : '192.168.56.3'}, intfName1='r4-eth2', params0={'192.168.56.2'})
net.addLink(r4, r5, intfName1='r4-eth1', params1={ 'ip' : '10.0.2.1/24'}, intfName2='r5-eth2', params2={'192.168.56.1'})

info( '*** Starting network\n')
net.build()

info( '*** Starting controllers\n')
for controller in net.controllers:
controller.start()

info( '*** Starting switches\n')
net.get('s2').start([c0])
net.get('s1').start([c0])

info( '*** Post configure switches and hosts\n')
CLI(net)
net.stop()
if __name__ == '__main__':
setLogLevel( 'info' )
myNetwork()

Answer 1

inuxrouter.py: Example network with Linux IP router
	This example converts a Node into a router using IP forwarding
	already built into Linux.
	The example topology creates a router and three IP subnets:
	- 192.168.1.0/24 (r0-eth1, IP: 192.168.1.1)
	- 172.16.0.0/12 (r0-eth2, IP: 172.16.0.1)
	- 10.0.0.0/8 (r0-eth3, IP: 10.0.0.1)
	Each subnet consists of a single host connected to
	a single switch:
	r0-eth1 - s1-eth1 - h1-eth0 (IP: 192.168.1.100)
	r0-eth2 - s2-eth1 - h2-eth0 (IP: 172.16.0.100)
	r0-eth3 - s3-eth1 - h3-eth0 (IP: 10.0.0.100)
	The example relies on default routing entries that are
	automatically created for each router interface, as well
	as 'defaultRoute' parameters for the host interfaces.
	Additional routes may be added to the router or hosts by
	executing 'ip route' or 'route' commands on the router or hosts.
	"""
	from mininet.topo import Topo
	from mininet.net import Mininet
	from mininet.node import Node
	from mininet.log import setLogLevel, info
	from mininet.cli import CLI
	class LinuxRouter( Node ):
	"A Node with IP forwarding enabled."
	def config( self, **params ):
	super( LinuxRouter, self).config( **params )
	# Enable forwarding on the router
	self.cmd( 'sysctl net.ipv4.ip_forward=1' )
	def terminate( self ):
	self.cmd( 'sysctl net.ipv4.ip_forward=0' )
	super( LinuxRouter, self ).terminate()
	class NetworkTopo( Topo ):
	"A LinuxRouter connecting three IP subnets"
	def build( self, **_opts ):
	defaultIP = '192.168.1.1/24' # IP address for r0-eth1
	router = self.addNode( 'r0', cls=LinuxRouter, ip=defaultIP )
	s1, s2, s3 = [ self.addSwitch( s ) for s in ( 's1', 's2', 's3' ) ]
	self.addLink( s1, router, intfName2='r0-eth1',
	params2={ 'ip' : defaultIP } ) # for clarity
	self.addLink( s2, router, intfName2='r0-eth2',
	params2={ 'ip' : '172.16.0.1/12' } )
	self.addLink( s3, router, intfName2='r0-eth3',
	params2={ 'ip' : '10.0.0.1/8' } )
	h1 = self.addHost( 'h1', ip='192.168.1.100/24',
	defaultRoute='via 192.168.1.1' )
	h2 = self.addHost( 'h2', ip='172.16.0.100/12',
	defaultRoute='via 172.16.0.1' )
	h3 = self.addHost( 'h3', ip='10.0.0.100/8',
	defaultRoute='via 10.0.0.1' )
	for h, s in [ (h1, s1), (h2, s2), (h3, s3) ]:
	self.addLink( h, s )
	def run():
	"Test linux router"
	topo = NetworkTopo()
	net = Mininet( topo=topo ) # controller is used by s1-s3
	net.start()
	info( '*** Routing Table on Router:\n' )
	info( net[ 'r0' ].cmd( 'route' ) )
	CLI( net )
	net.stop()
	if __name__ == '__main__':
	setLogLevel( 'info' )
	run()