add 1ms delay to all links to exaggerate TCP bandwidth decrease across an...

add 1ms delay to all links to exaggerate TCP bandwidth decrease across an increasing number of links

examples/linearbandwidth.py

@@ -24,10 +24,12 @@
 """
 
 from mininet.net import Mininet
-from mininet.node import OVSKernelSwitch, Controller
+from mininet.node import UserSwitch, OVSKernelSwitch, Controller
 from mininet.topo import Topo
 from mininet.log import lg
 from mininet.util import irange
+from mininet.link import TCLink
+from functools import partial
 
 import sys
 flush = sys.stdout.flush
@@ -67,15 +69,23 @@ def linearBandwidthTest( lengths ):
     switchCount = max( lengths )
     hostCount = switchCount + 1
 
-    switches = { 'Open vSwitch kernel': OVSKernelSwitch }
+    switches = { 'reference user': UserSwitch,
+                 'Open vSwitch kernel': OVSKernelSwitch }
 
     topo = LinearTestTopo( hostCount )
 
     for datapath in switches.keys():
+        # we can remove this later when/if the userswitch is fixed
+        if switches[ datapath ] is UserSwitch:
+            print "*** Skipping User Switch due to poor performance"
+            continue
         print "*** testing", datapath, "datapath"
         Switch = switches[ datapath ]
         results[ datapath ] = []
-        net = Mininet( topo=topo, switch=Switch, controller=Controller, waitConnected=True )
+        link = partial( TCLink, delay='1ms' )
+        net = Mininet( topo=topo, switch=Switch,
+                       controller=Controller, waitConnected=True,
+                       link=link )
         net.start()
         print "*** testing basic connectivity"
         for n in lengths: