linearbandwidth.py

#!/usr/bin/python

"""
Test bandwidth (using iperf) on linear networks of varying size,
using both kernel and user datapaths.

We construct a network of N hosts and N-1 switches, connected as follows:

h1 <-> s1 <-> s2 .. sN-1
       |       |    |
       h2      h3   hN

WARNING: by default, the reference controller only supports 16
switches, so this test WILL NOT WORK unless you have recompiled
your controller to support 100 switches (or more.)

In addition to testing the bandwidth across varying numbers
of switches, this example demonstrates:

- creating a custom topology, LinearTestTopo
- using the ping() and iperf() tests from Mininet()
- testing both the kernel and user switches

"""

from mininet.net import Mininet
from mininet.node import UserSwitch, OVSKernelSwitch
from mininet.topo import Topo
from mininet.log import lg
from mininet.util import irange

import sys
flush = sys.stdout.flush

class LinearTestTopo( Topo ):
    "Topology for a string of N hosts and N-1 switches."

    def __init__( self, N, **params ):

        # Initialize topology
        Topo.__init__( self, **params )

        # Create switches and hosts
        hosts = [ self.addHost( 'h%s' % h )
                  for h in irange( 1, N ) ]
        switches = [ self.addSwitch( 's%s' % s )
                     for s in irange( 1, N - 1 ) ]

        # Wire up switches
        last = None
        for switch in switches:
            if last:
                self.addLink( last, switch )
            last = switch

        # Wire up hosts
        self.addLink( hosts[ 0 ], switches[ 0 ] )
        for host, switch in zip( hosts[ 1: ], switches ):
            self.addLink( host, switch )


def linearBandwidthTest( lengths ):

    "Check bandwidth at various lengths along a switch chain."

    results = {}
    switchCount = max( lengths )
    hostCount = switchCount + 1

    switches = { 'reference user': UserSwitch,
                 'Open vSwitch kernel': OVSKernelSwitch }

    topo = LinearTestTopo( hostCount )

    for datapath in switches.keys():
        print "*** testing", datapath, "datapath"
        Switch = switches[ datapath ]
        results[ datapath ] = []
        net = Mininet( topo=topo, switch=Switch )
        net.start()
        print "*** testing basic connectivity"
        for n in lengths:
            net.ping( [ net.hosts[ 0 ], net.hosts[ n ] ] )
        print "*** testing bandwidth"
        for n in lengths:
            src, dst = net.hosts[ 0 ], net.hosts[ n ]
            print "testing", src.name, "<->", dst.name,
            bandwidth = net.iperf( [ src, dst ] )
            print bandwidth
            flush()
            results[ datapath ] += [ ( n, bandwidth ) ]
        net.stop()

    for datapath in switches.keys():
        print
        print "*** Linear network results for", datapath, "datapath:"
        print
        result = results[ datapath ]
        print "SwitchCount\tiperf Results"
        for switchCount, bandwidth in result:
            print switchCount, '\t\t',
            print bandwidth[ 0 ], 'server, ', bandwidth[ 1 ], 'client'
        print
    print

if __name__ == '__main__':
    lg.setLogLevel( 'info' )
    sizes = [ 1, 10, 20, 40, 60, 80, 100 ]
    print "*** Running linearBandwidthTest", sizes
    linearBandwidthTest( sizes  )