diff --git a/mininet/net.py b/mininet/net.py
index 135163b..d1dafab 100755
--- a/mininet/net.py
+++ b/mininet/net.py
@@ -235,6 +235,9 @@ class Mininet( object ):
             # BL: do we want to do this here or not?
             # May not make sense if we have CPU lmiting...
             # quietRun( 'renice +18 -p ' + repr( host.pid ) )
+            # This may not be the right place to do this, but
+            # it needs to be done somewhere.
+            host.cmd( 'ifconfig lo up' )
         info( '\n' )
 
     def buildFromTopo( self, topo=None ):