CI matrix build + 20.04 fixes (#990)

Ubuntu 20.04 fixes:
- fixes sshd test
- speeds up examples/{treeping64,tree1024}.py
- debugging hacks/output for testLinkChange
- removes cfs from examples/popen.py
- improves nat in nodelib (netplan fixes?)
- makes some tests executable
- waits for switches to connect in tests to
  avoid race conditions
-- adds mn -w option and wait CLI command
Changes:
- REMOVES default "-v" argument for Controller()
  and adds verbose(=False) option; avoiding logging
  makes it faster
- CHANGES waitConnected to wait for 5 seconds
  as documented; we may wish to implement an argument
  to -w to set this timeout
Issues?
- There may still be an issue with the ovs-netplan-clean
  service causing the boot to hang ;-(

.github/workflows/run-tests.yaml

@@ -9,7 +9,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-18.04, ubuntu-16.04]
+        os: [ubuntu-20.04, ubuntu-18.04, ubuntu-16.04]
         python-version: [3.x, 2.x]
     steps:
       - name: Check out Mininet source
@@ -47,12 +47,10 @@ jobs:
           export sudo="sudo env PATH=$PATH"
           export PYTHON=`which python`
           rm -f pexpect.out
-          $sudo $PYTHON mininet/test/runner.py -v -quick || \
+          $sudo $PYTHON mininet/test/runner.py -v -quick
-            (cat pexpect.out && exit 1)
       - name: Run examples tests (quick)
         run: |
           export sudo="sudo env PATH=$PATH"
           export PYTHON=`which python`
           rm -f pexpect.out
-          $sudo $PYTHON examples/test/runner.py -v -quick || \
+          $sudo $PYTHON examples/test/runner.py -v -quick
-            (cat pexpect.out && exit 1)

README.md

@@ -132,4 +132,4 @@ Bob Lantz
 Mininet Core Team
 
 [1]: https://travis-ci.org/mininet/mininet.svg?branch=master
-[2]: https://github.com/mininet/mininet/workflows/mininet%20tests/badge.svg
+[2]: https://github.com/mininet/mininet/workflows/mininet-tests/badge.svg

bin/mn

@@ -284,6 +284,8 @@ class MininetRunner( object ):
                          " Mininet's IP subnet, see the --ipbase option." )
         opts.add_option( '--version', action='callback', callback=version,
                          help='prints the version and exits' )
+        opts.add_option( '--wait', '-w', action='store_true',
+                         default=False, help='wait for switches to connect' )
         opts.add_option( '--cluster', type='string', default=None,
                          metavar='server1,server2...',
                          help=( 'run on multiple servers (experimental!)' ) )
@@ -385,6 +387,7 @@ class MininetRunner( object ):
                   ipBase=opts.ipbase, inNamespace=opts.innamespace,
                   xterms=opts.xterms, autoSetMacs=opts.mac,
                   autoStaticArp=opts.arp, autoPinCpus=opts.pin,
+                  waitConnected=opts.wait,
                   listenPort=opts.listenport )
 
         if opts.ensure_value( 'nat', False ):

examples/bind.py

@@ -53,7 +53,7 @@ def testHostWithPrivateDirs():
                       '/var/mn' ]
     host = partial( Host,
                     privateDirs=privateDirs )
-    net = Mininet( topo=topo, host=host )
+    net = Mininet( topo=topo, host=host, waitConnected=True )
     net.start()
     directories = [ directory[ 0 ] if isinstance( directory, tuple )
                     else directory for directory in privateDirs ]

examples/cluster.py

@@ -875,7 +875,7 @@ class MininetCluster( Mininet ):
 
 def testNsTunnels( remote='ubuntu2', link=RemoteGRELink ):
     "Test tunnels between nodes in namespaces"
-    net = Mininet( host=RemoteHost, link=link )
+    net = Mininet( host=RemoteHost, link=link, waitConnected=True )
     h1 = net.addHost( 'h1')
     h2 = net.addHost( 'h2', server=remote )
     net.addLink( h1, h2 )
@@ -891,7 +891,8 @@ def testNsTunnels( remote='ubuntu2', link=RemoteGRELink ):
 def testRemoteNet( remote='ubuntu2', link=RemoteGRELink ):
     "Test remote Node classes"
     info( '*** Remote Node Test\n' )
-    net = Mininet( host=RemoteHost, switch=RemoteOVSSwitch, link=link )
+    net = Mininet( host=RemoteHost, switch=RemoteOVSSwitch, link=link,
+                   waitConnected=True )
     c0 = net.addController( 'c0' )
     # Make sure controller knows its non-loopback address
     Intf( 'eth0', node=c0 ).updateIP()

examples/clusterperf.py

@@ -8,7 +8,7 @@ from mininet.log import setLogLevel
 
 def perf(Link):
     "Test connectivity nand performance over Link"
-    net = Mininet( host=RemoteHost, link=Link )
+    net = Mininet( host=RemoteHost, link=Link, waitConnected=True )
     h1 = net.addHost( 'h1')
     h2 = net.addHost( 'h2', server='ubuntu2' )
     net.addLink( h1, h2 )

examples/controllers.py

@@ -27,7 +27,7 @@ class MultiSwitch( OVSSwitch ):
         return OVSSwitch.start( self, [ cmap[ self.name ] ] )
 
 topo = TreeTopo( depth=2, fanout=2 )
-net = Mininet( topo=topo, switch=MultiSwitch, build=False )
+net = Mininet( topo=topo, switch=MultiSwitch, build=False, waitConnected=True )
 for c in [ c0, c1 ]:
     net.addController(c)
 net.build()

examples/controllers2.py

@@ -20,7 +20,8 @@ from mininet.log import setLogLevel, info
 def multiControllerNet():
     "Create a network from semi-scratch with multiple controllers."
 
-    net = Mininet( controller=Controller, switch=OVSSwitch )
+    net = Mininet( controller=Controller, switch=OVSSwitch,
+                   waitConnected=True )
 
     info( "*** Creating (reference) controllers\n" )
     c1 = net.addController( 'c1', port=6633 )

examples/controlnet.py

@@ -123,7 +123,8 @@ def run():
 
     info( '* Creating Control Network\n' )
     ctopo = ControlNetwork( n=4, dataController=DataController )
-    cnet = Mininet( topo=ctopo, ipBase='192.168.123.0/24', controller=None )
+    cnet = Mininet( topo=ctopo, ipBase='192.168.123.0/24',
+                    controller=None, waitConnected=True )
     info( '* Adding Control Network Controller\n')
     cnet.addController( 'cc0', controller=Controller )
     info( '* Starting Control Network\n')
@@ -133,7 +134,8 @@ def run():
     topo = TreeTopo( depth=2, fanout=2 )
     # UserSwitch so we can easily test failover
     sw = partial( UserSwitch, opts='--inactivity-probe=1 --max-backoff=1' )
-    net = Mininet( topo=topo, switch=sw, controller=None )
+    net = Mininet( topo=topo, switch=sw, controller=None,
+                   waitConnected=True )
     info( '* Adding Controllers to Data Network\n' )
     for host in cnet.hosts:
         if isinstance(host, Controller):

examples/cpu.py

@@ -52,7 +52,7 @@ def bwtest( cpuLimits, period_us=100000, seconds=10 ):
                            period_us=period_us,
                            cpu=.5*cpu )
             try:
-                net = Mininet( topo=topo, host=host )
+                net = Mininet( topo=topo, host=host, waitConnected=True )
             # pylint: disable=bare-except
             except:
                 info( '*** Skipping scheduler %s and cleaning up\n' % sched )

examples/emptynet.py

@@ -14,7 +14,7 @@ def emptyNet():
 
     "Create an empty network and add nodes to it."
 
-    net = Mininet( controller=Controller )
+    net = Mininet( controller=Controller, waitConnected=True )
 
     info( '*** Adding controller\n' )
     net.addController( 'c0' )

examples/hwintf.py

@@ -38,7 +38,7 @@ if __name__ == '__main__':
     checkIntf( intfName )
 
     info( '*** Creating network\n' )
-    net = Mininet( topo=TreeTopo( depth=1, fanout=2 ) )
+    net = Mininet( topo=TreeTopo( depth=1, fanout=2 ), waitConnected=True )
 
     switch = net.switches[ 0 ]
     info( '*** Adding hardware interface', intfName, 'to switch',

examples/intfoptions.py

@@ -13,7 +13,7 @@ from mininet.link import TCLink
 
 def intfOptions():
     "run various traffic control commands on a single interface"
-    net = Mininet( autoStaticArp=True )
+    net = Mininet( autoStaticArp=True, waitConnected=True )
     net.addController( 'c0' )
     h1 = net.addHost( 'h1' )
     h2 = net.addHost( 'h2' )

examples/limit.py

@@ -34,7 +34,7 @@ def limit( bw=10, cpu=.1 ):
                       'Skipping this test\n' )
                 continue
         host = custom( CPULimitedHost, sched=sched, cpu=cpu )
-        net = Mininet( topo=myTopo, intf=intf, host=host )
+        net = Mininet( topo=myTopo, intf=intf, host=host, waitConnected=True )
         net.start()
         testLinkLimit( net, bw=bw )
         net.runCpuLimitTest( cpu=cpu )
@@ -43,7 +43,7 @@ def limit( bw=10, cpu=.1 ):
 def verySimpleLimit( bw=150 ):
     "Absurdly simple limiting test"
     intf = custom( TCIntf, bw=bw )
-    net = Mininet( intf=intf )
+    net = Mininet( intf=intf, waitConnected=True )
     h1, h2 = net.addHost( 'h1' ), net.addHost( 'h2' )
     net.addLink( h1, h2 )
     net.start()

examples/linearbandwidth.py

@@ -83,10 +83,10 @@ def linearBandwidthTest( lengths ):
         info( "*** testing", datapath, "datapath\n" )
         Switch = switches[ datapath ]
         results[ datapath ] = []
-        link = partial( TCLink, delay='2ms', bw=10 )
+        link = partial( TCLink, delay='30ms', bw=100 )
         net = Mininet( topo=topo, switch=Switch,
-                       controller=Controller, waitConnected=True,
+                       controller=Controller, link=link,
-                       link=link )
+                       waitConnected=True )
         net.start()
         info( "*** testing basic connectivity\n" )
         for n in lengths:
@@ -99,7 +99,7 @@ def linearBandwidthTest( lengths ):
             src.cmd( 'telnet', dst.IP(), '5001' )
             info( "testing", src.name, "<->", dst.name, '\n' )
             # serverbw = received; _clientbw = buffered
-            serverbw, _clientbw = net.iperf( [ src, dst ], seconds=10 )
+            serverbw, _clientbw = net.iperf( [ src, dst ], seconds=5 )
             info( serverbw, '\n' )
             flush()
             results[ datapath ] += [ ( n, serverbw ) ]
@@ -117,6 +117,6 @@ def linearBandwidthTest( lengths ):
 
 if __name__ == '__main__':
     lg.setLogLevel( 'info' )
-    sizes = [ 1, 10, 20, 40, 60, 80 ]
+    sizes = [ 1, 2, 3, 4 ]
     info( "*** Running linearBandwidthTest", sizes, '\n' )
     linearBandwidthTest( sizes  )

examples/linuxrouter.py

@@ -79,7 +79,8 @@ class NetworkTopo( Topo ):
 def run():
     "Test linux router"
     topo = NetworkTopo()
-    net = Mininet( topo=topo )  # controller is used by s1-s3
+    net = Mininet( topo=topo,
+                   waitConnected=True )  # controller is used by s1-s3
     net.start()
     info( '*** Routing Table on Router:\n' )
     info( net[ 'r0' ].cmd( 'route' ) )

examples/mobility.py

@@ -107,7 +107,8 @@ def moveHost( host, oldSwitch, newSwitch, newPort=None ):
 def mobilityTest():
     "A simple test of mobility"
     info( '* Simple mobility test\n' )
-    net = Mininet( topo=LinearTopo( 3 ), switch=MobilitySwitch )
+    net = Mininet( topo=LinearTopo( 3 ), switch=MobilitySwitch,
+                                    waitConnected=True )
     info( '* Starting network:\n' )
     net.start()
     printConnections( net.switches )

examples/multilink.py

@@ -13,7 +13,7 @@ from mininet.topo import Topo
 def runMultiLink():
     "Create and run multiple link network"
     topo = simpleMultiLinkTopo( n=2 )
-    net = Mininet( topo=topo )
+    net = Mininet( topo=topo, waitConnected=True )
     net.start()
     CLI( net )
     net.stop()

examples/multipoll.py

@@ -53,7 +53,7 @@ def monitorFiles( outfiles, seconds, timeoutms ):
 def monitorTest( N=3, seconds=3 ):
     "Run pings and monitor multiple hosts"
     topo = SingleSwitchTopo( N )
-    net = Mininet( topo )
+    net = Mininet( topo, waitConnected=True )
     net.start()
     hosts = net.hosts
     info( "Starting test...\n" )

examples/multitest.py

@@ -22,7 +22,8 @@ if __name__ == '__main__':
     info( "*** Initializing Mininet and kernel modules\n" )
     OVSKernelSwitch.setup()
     info( "*** Creating network\n" )
-    network = Mininet( TreeTopo( depth=2, fanout=2 ), switch=OVSKernelSwitch )
+    network = Mininet( TreeTopo( depth=2, fanout=2), switch=OVSKernelSwitch,
+                       waitConnected=True )
     info( "*** Starting network\n" )
     network.start()
     info( "*** Running ping test\n" )

examples/nat.py

@@ -12,7 +12,7 @@ from mininet.topolib import TreeNet
 
 if __name__ == '__main__':
     lg.setLogLevel( 'info')
-    net = TreeNet( depth=1, fanout=4 )
+    net = TreeNet( depth=1, fanout=4, waitConnected=True )
     # Add NAT connectivity
     net.addNAT().configDefault()
     net.start()

examples/natnet.py

@@ -57,7 +57,7 @@ class InternetTopo(Topo):
 def run():
     "Create network and run the CLI"
     topo = InternetTopo()
-    net = Mininet(topo=topo)
+    net = Mininet(topo=topo, waitConnected=True )
     net.start()
     CLI(net)
     net.stop()

examples/numberedports.py

@@ -28,7 +28,7 @@ def testPortNumbering():
        mid-level API) and check that implicit and
        explicit port numbering works as expected."""
 
-    net = Mininet( controller=Controller )
+    net = Mininet( controller=Controller, waitConnected=True )
 
     info( '*** Adding controller\n' )
     net.addController( 'c0' )

examples/popen.py

@@ -5,19 +5,15 @@ This example monitors a number of hosts using host.popen() and
 pmonitor()
 """
 
-
 from mininet.net import Mininet
-from mininet.node import CPULimitedHost
 from mininet.topo import SingleSwitchTopo
 from mininet.log import setLogLevel, info
-from mininet.util import custom, pmonitor
+from mininet.util import pmonitor
 
-def monitorhosts( hosts=5, sched='cfs' ):
+def monitorhosts( hosts=5 ):
     "Start a bunch of pings and monitor them using popen"
     mytopo = SingleSwitchTopo( hosts )
-    cpu = .5 / hosts
+    net = Mininet( topo=mytopo, waitConnected=True )
-    myhost = custom( CPULimitedHost, cpu=cpu, sched=sched )
-    net = Mininet( topo=mytopo, host=myhost )
     net.start()
     # Start a bunch of pings
     popens = {}

examples/popenpoll.py

@@ -13,7 +13,7 @@ from signal import SIGINT
 def pmonitorTest( N=3, seconds=10 ):
     "Run pings and monitor multiple hosts using pmonitor"
     topo = SingleSwitchTopo( N )
-    net = Mininet( topo )
+    net = Mininet( topo, waitConnected=True )
     net.start()
     hosts = net.hosts
     info( "Starting test...\n" )

examples/sshd.py

@@ -29,7 +29,7 @@ from mininet.util import waitListening
 def TreeNet( depth=1, fanout=2, **kwargs ):
     "Convenience function for creating tree networks."
     topo = TreeTopo( depth, fanout )
-    return Mininet( topo, **kwargs )
+    return Mininet( topo, waitConnected=True, **kwargs )
 
 def connectToRootNS( network, switch, ip, routes ):
     """Connect hosts to root namespace via switch. Starts network.

examples/test/test_clusterSanity.py

@@ -14,6 +14,8 @@ class clusterSanityCheck( unittest.TestCase ):
     def testClusterPingAll( self ):
         p = pexpect.spawn( 'python -m mininet.examples.clusterSanity' )
         p.expect( self.prompt )
+        p.sendline( 'py net.waitConnected()' )
+        p.expect( self.prompt )
         p.sendline( 'pingall' )
         p.expect ( '(\d+)% dropped' )
         percent = int( p.match.group( 1 ) ) if p.match else -1

examples/test/test_sshd.py

@@ -16,7 +16,8 @@ class testSSHD( unittest.TestCase ):
         "Log into ssh server, check banner, then exit"
         # Note: this test will fail if "Welcome" is not in the sshd banner
         # and '#'' or '$'' are not in the prompt
-        p = pexpect.spawn( 'ssh -i /tmp/ssh/test_rsa %s' % ip, timeout=10 )
+        ssh = 'ssh -o StrictHostKeyChecking=no -i /tmp/ssh/test_rsa ' + ip
+        p = pexpect.spawn( ssh, timeout=5 )
         while True:
             index = p.expect( self.opts )
             if index == 0:
@@ -57,4 +58,3 @@ class testSSHD( unittest.TestCase ):
 
 if __name__ == '__main__':
     unittest.main()
-

examples/tree1024.py

@@ -9,10 +9,13 @@ and running sysctl -p. Check util/sysctl_addon.
 
 from mininet.cli import CLI
 from mininet.log import setLogLevel
-from mininet.node import OVSSwitch
+from mininet.node import OVSSwitch, Host
 from mininet.topolib import TreeNet
+from mininet.examples.treeping64 import HostV4, QuietController
 
 if __name__ == '__main__':
     setLogLevel( 'info' )
-    network = TreeNet( depth=2, fanout=32, switch=OVSSwitch )
+    network = TreeNet( depth=2, fanout=32, host=HostV4,
+                       switch=OVSSwitch, controller=QuietController,
+                       waitConnected=True)
     network.run( CLI, network )

examples/treeping64.py

@@ -4,21 +4,34 @@
 
 
 from mininet.log import setLogLevel, info
-from mininet.node import UserSwitch, OVSKernelSwitch  # , KernelSwitch
+from mininet.node import UserSwitch, OVSKernelSwitch, Host, Controller
 from mininet.topolib import TreeNet
 
+
+class HostV4( Host ):
+    "Try to IPv6 and its awful neighbor discovery"
+    def __init__( self, *args, **kwargs ):
+        super( HostV4, self ).__init__( *args, **kwargs )
+        cfgs = [ 'all.disable_ipv6=1', 'default.disable_ipv6=1',
+                 'default.autoconf=0', 'lo.autoconf=0' ]
+        for cfg in cfgs:
+            self.cmd( 'sysctl -w net.ipv6.conf.' + cfg )
+
+
+
+
 def treePing64():
     "Run ping test on 64-node tree networks."
 
     results = {}
-    switches = {  # 'reference kernel': KernelSwitch,
+    switches = { 'reference user': UserSwitch,
-                  'reference user': UserSwitch,
+                 'Open vSwitch kernel': OVSKernelSwitch }
-                  'Open vSwitch kernel': OVSKernelSwitch }
 
     for name in switches:
         info( "*** Testing", name, "datapath\n" )
         switch = switches[ name ]
-        network = TreeNet( depth=2, fanout=8, switch=switch )
+        network = TreeNet( depth=2, fanout=8, switch=switch,
+                           waitConnected=True )
         result = network.run( network.pingAll )
         results[ name ] = result
 

examples/vlanhost.py

@@ -65,7 +65,7 @@ def exampleAllHosts( vlan ):
 
     # Start a basic network using our VLANHost
     topo = SingleSwitchTopo( k=2 )
-    net = Mininet( host=host, topo=topo )
+    net = Mininet( host=host, topo=topo, waitConnected=True )
     net.start()
     CLI( net )
     net.stop()
@@ -96,7 +96,7 @@ class VLANStarTopo( Topo ):
 def exampleCustomTags():
     """Simple example that exercises VLANStarTopo"""
 
-    net = Mininet( topo=VLANStarTopo() )
+    net = Mininet( topo=VLANStarTopo(), waitConnected=True )
     net.start()
     CLI( net )
     net.stop()

mininet/cli.py

@@ -399,6 +399,10 @@ class CLI( Cmd ):
                 error( 'invalid command: '
                        'switch <switch name> {start, stop}\n' )
 
+    def do_wait( self, line ):
+        "Wait until all switches have connected to a controller"
+        self.mn.waitConnected()
+
     def default( self, line ):
         """Called on an input line when the command prefix is not recognized.
            Overridden to run shell commands when a node is the first

mininet/net.py

@@ -173,7 +173,7 @@ class Mininet( object ):
         if topo and build:
             self.build()
 
-    def waitConnected( self, timeout=None, delay=.5 ):
+    def waitConnected( self, timeout=5, delay=.5 ):
         """wait for each switch to connect to a controller,
            up to 5 seconds
            timeout: time to wait, or None to wait indefinitely

mininet/node.py

@@ -1382,10 +1382,12 @@ class Controller( Node ):
        OpenFlow controller."""
 
     def __init__( self, name, inNamespace=False, command='controller',
-                  cargs='-v ptcp:%d', cdir=None, ip="127.0.0.1",
+                  cargs='ptcp:%d', cdir=None, ip="127.0.0.1",
-                  port=6653, protocol='tcp', **params ):
+                  port=6653, protocol='tcp', verbose=False, **params ):
         self.command = command
         self.cargs = cargs
+        if verbose:
+            cargs = '-v ' + cargs
         self.cdir = cdir
         # Accept 'ip:port' syntax as shorthand
         if ':' in ip:

mininet/nodelib.py

@@ -84,13 +84,35 @@ class NAT( Node ):
         self.flush = flush
         self.forwardState = self.cmd( 'sysctl -n net.ipv4.ip_forward' ).strip()
 
+    def setManualConfig( self, intf ):
+        """Prevent network-manager/networkd from messing with our interface
+           by specifying manual configuration in /etc/network/interfaces"""
+        cfile = '/etc/network/interfaces'
+        line = '\niface %s inet manual\n' % intf
+        try:
+            with open( cfile ) as f:
+                config = f.read()
+        except IOError:
+            config = ''
+        if ( line ) not in config:
+            info( '*** Adding "' + line.strip() + '" to ' + cfile + '\n' )
+            with open( cfile, 'a' ) as f:
+                f.write( line )
+            # Probably need to restart network manager to be safe -
+            # hopefully this won't disconnect you
+            self.cmd( 'service network-manager restart || netplan apply' )
+
     def config( self, **params ):
         """Configure the NAT and iptables"""
-        super( NAT, self).config( **params )
 
         if not self.localIntf:
             self.localIntf = self.defaultIntf()
 
+        self.setManualConfig( self.localIntf )
+
+        # Now we can configure manually without interference
+        super( NAT, self).config( **params )
+
         if self.flush:
             self.cmd( 'sysctl net.ipv4.ip_forward=0' )
             self.cmd( 'iptables -F' )
@@ -114,19 +136,7 @@ class NAT( Node ):
         # Instruct the kernel to perform forwarding
         self.cmd( 'sysctl net.ipv4.ip_forward=1' )
 
-        # Prevent network-manager from messing with our interface
+
-        # by specifying manual configuration in /etc/network/interfaces
-        intf = self.localIntf
-        cfile = '/etc/network/interfaces'
-        line = '\niface %s inet manual\n' % intf
-        config = open( cfile ).read()
-        if ( line ) not in config:
-            info( '*** Adding "' + line.strip() + '" to ' + cfile + '\n' )
-            with open( cfile, 'a' ) as f:
-                f.write( line )
-        # Probably need to restart network-manager to be safe -
-        # hopefully this won't disconnect you
-        self.cmd( 'service network-manager restart' )
 
     def terminate( self ):
         "Stop NAT/forwarding between Mininet and external network"

mininet/test/test_walkthrough.py

@@ -43,17 +43,18 @@ class testWalkthrough( unittest.TestCase ):
             tshark = pexpect.spawn( 'tshark -i lo -R of' )
         else:
             tshark = pexpect.spawn( 'tshark -i lo -Y openflow_v1' )
-        tshark.expect( [ 'Capturing on lo', "Capturing on 'Loopback'" ] )
+        tshark.expect( [ 'Capturing on lo', "Capturing on 'Loopback" ] )
         mn = pexpect.spawn( 'mn --test pingall' )
         mn.expect( '0% dropped' )
         tshark.expect( [ '74 Hello', '74 of_hello', '74 Type: OFPT_HELLO' ] )
         tshark.sendintr()
         mn.expect( pexpect.EOF )
+        tshark.expect( 'aptured' )  # 'xx packets captured'
         tshark.expect( pexpect.EOF )
 
     def testBasic( self ):
         "Test basic CLI commands (help, nodes, net, dump)"
-        p = pexpect.spawn( 'mn' )
+        p = pexpect.spawn( 'mn -w' )
         p.expect( self.prompt )
         # help command
         p.sendline( 'help' )
@@ -92,7 +93,7 @@ class testWalkthrough( unittest.TestCase ):
 
     def testHostCommands( self ):
         "Test ifconfig and ps on h1 and s1"
-        p = pexpect.spawn( 'mn' )
+        p = pexpect.spawn( 'mn -w' )
         p.expect( self.prompt )
         # Third pattern is a local interface beginning with 'eth' or 'en'
         interfaces = [ r'h1-eth0[:\s]', r's1-eth1[:\s]',
@@ -144,7 +145,7 @@ class testWalkthrough( unittest.TestCase ):
 
     def testConnectivity( self ):
         "Test ping and pingall"
-        p = pexpect.spawn( 'mn' )
+        p = pexpect.spawn( 'mn -w' )
         p.expect( self.prompt )
         p.sendline( 'h1 ping -c 1 h2' )
         p.expect( '1 packets transmitted, 1 received' )
@@ -161,7 +162,7 @@ class testWalkthrough( unittest.TestCase ):
             httpserver = 'SimpleHTTPServer'
         else:
             httpserver = 'http.server'
-        p = pexpect.spawn( 'mn' )
+        p = pexpect.spawn( 'mn -w' )
         p.expect( self.prompt )
         p.sendline( 'h1 python -m %s 80 &' % httpserver )
         # The walkthrough doesn't specify a delay here, and
@@ -213,7 +214,9 @@ class testWalkthrough( unittest.TestCase ):
 
     def testLinkChange( self ):
         "Test TCLink bw and delay"
-        p = pexpect.spawn( 'mn --link tc,bw=10,delay=10ms' )
+        p = pexpect.spawn( 'mn -w --link tc,bw=10,delay=10ms' )
+        p.expect( self.prompt )
+        p.sendline( 'h1 route && ping -c1 h2' )
         # test bw
         p.expect( self.prompt )
         p.sendline( 'iperf' )
@@ -319,7 +322,7 @@ class testWalkthrough( unittest.TestCase ):
     # PART 3
     def testPythonInterpreter( self ):
         "Test py and px by checking IP for h1 and adding h3"
-        p = pexpect.spawn( 'mn' )
+        p = pexpect.spawn( 'mn -w' )
         p.expect( self.prompt )
         # test host IP
         p.sendline( 'py h1.IP()' )
@@ -341,7 +344,7 @@ class testWalkthrough( unittest.TestCase ):
 
     def testLink( self ):
         "Test link CLI command using ping"
-        p = pexpect.spawn( 'mn' )
+        p = pexpect.spawn( 'mn -w' )
         p.expect( self.prompt )
         p.sendline( 'link s1 h1 down' )
         p.expect( self.prompt )