Bob Lantz
54bd4e4d3a
than CPU-limited, which should expose the feature we are trying to demonstrate (TCP data rate slowing down as latency increases due to congestion control.)
127 lines
4.0 KiB
Python
Executable File
127 lines
4.0 KiB
Python
Executable File
#!/usr/bin/python
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"""
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Test bandwidth (using iperf) on linear networks of varying size,
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using both kernel and user datapaths.
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We construct a network of N hosts and N-1 switches, connected as follows:
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h1 <-> s1 <-> s2 .. sN-1
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h2 h3 hN
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WARNING: by default, the reference controller only supports 16
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switches, so this test WILL NOT WORK unless you have recompiled
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your controller to support 100 switches (or more.)
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In addition to testing the bandwidth across varying numbers
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of switches, this example demonstrates:
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- creating a custom topology, LinearTestTopo
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- using the ping() and iperf() tests from Mininet()
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- testing both the kernel and user switches
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"""
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from mininet.net import Mininet
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from mininet.node import UserSwitch, OVSKernelSwitch, Controller
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from mininet.topo import Topo
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from mininet.log import lg, info
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from mininet.util import irange, quietRun
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from mininet.link import TCLink
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from functools import partial
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import sys
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flush = sys.stdout.flush
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class LinearTestTopo( Topo ):
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"Topology for a string of N hosts and N-1 switches."
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def __init__( self, N, **params ):
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# Initialize topology
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Topo.__init__( self, **params )
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# Create switches and hosts
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hosts = [ self.addHost( 'h%s' % h )
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for h in irange( 1, N ) ]
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switches = [ self.addSwitch( 's%s' % s )
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for s in irange( 1, N - 1 ) ]
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# Wire up switches
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last = None
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for switch in switches:
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if last:
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self.addLink( last, switch )
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last = switch
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# Wire up hosts
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self.addLink( hosts[ 0 ], switches[ 0 ] )
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for host, switch in zip( hosts[ 1: ], switches ):
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self.addLink( host, switch )
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def linearBandwidthTest( lengths ):
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"Check bandwidth at various lengths along a switch chain."
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results = {}
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switchCount = max( lengths )
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hostCount = switchCount + 1
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switches = { 'reference user': UserSwitch,
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'Open vSwitch kernel': OVSKernelSwitch }
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# UserSwitch is horribly slow with recent kernels.
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# We can reinstate it once its performance is fixed
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del switches[ 'reference user' ]
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topo = LinearTestTopo( hostCount )
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# Select TCP Reno
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output = quietRun( 'sysctl -w net.ipv4.tcp_congestion_control=reno' )
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assert 'reno' in output
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for datapath in switches.keys():
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info( "*** testing", datapath, "datapath\n" )
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Switch = switches[ datapath ]
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results[ datapath ] = []
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link = partial( TCLink, delay='2ms', bw=10 )
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net = Mininet( topo=topo, switch=Switch,
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controller=Controller, waitConnected=True,
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link=link )
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net.start()
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info( "*** testing basic connectivity\n" )
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for n in lengths:
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net.ping( [ net.hosts[ 0 ], net.hosts[ n ] ] )
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info( "*** testing bandwidth\n" )
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for n in lengths:
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src, dst = net.hosts[ 0 ], net.hosts[ n ]
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# Try to prime the pump to reduce PACKET_INs during test
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# since the reference controller is reactive
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src.cmd( 'telnet', dst.IP(), '5001' )
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info( "testing", src.name, "<->", dst.name, '\n' )
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# serverbw = received; _clientbw = buffered
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serverbw, _clientbw = net.iperf( [ src, dst ], seconds=10 )
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info( serverbw, '\n' )
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flush()
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results[ datapath ] += [ ( n, serverbw ) ]
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net.stop()
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for datapath in switches.keys():
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info( "\n*** Linear network results for", datapath, "datapath:\n" )
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result = results[ datapath ]
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info( "SwitchCount\tiperf Results\n" )
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for switchCount, serverbw in result:
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info( switchCount, '\t\t' )
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info( serverbw, '\n' )
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info( '\n')
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info( '\n' )
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if __name__ == '__main__':
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lg.setLogLevel( 'info' )
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sizes = [ 1, 10, 20, 40, 60, 80 ]
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info( "*** Running linearBandwidthTest", sizes, '\n' )
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linearBandwidthTest( sizes )
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