diff --git a/mininet/link.py b/mininet/link.py
index 3bc63ec..a1d1ad9 100644
--- a/mininet/link.py
+++ b/mininet/link.py
@@ -465,13 +465,13 @@ class Link( object ):
     def delete( self ):
         "Delete this link"
         self.intf1.delete()
-        # We only need to delete one side, but this doesn't seem to
-        # cost us anything and may help subclasses.
-        self.intf2.delete()
+        # We only need to delete one side, though this doesn't seem to
+        # cost us much and might help subclasses.
+        # self.intf2.delete()
 
     def stop( self ):
         "Override to stop and clean up link as needed"
-        pass
+        self.delete()
 
     def status( self ):
         "Return link status as a string"
diff --git a/mininet/node.py b/mininet/node.py
index f263ad0..ffbedec 100644
--- a/mininet/node.py
+++ b/mininet/node.py
@@ -259,7 +259,7 @@ class Node( object ):
            and return without waiting for the command to complete.
            args: command and arguments, or string
            printPid: print command's PID?"""
-        assert not self.waiting
+        assert self.shell and not self.waiting
         printPid = kwargs.get( 'printPid', True )
         # Allow sendCmd( [ list ] )
         if len( args ) == 1 and isinstance( args[ 0 ], list ):
@@ -339,8 +339,11 @@ class Node( object ):
         verbose = kwargs.get( 'verbose', False )
         log = info if verbose else debug
         log( '*** %s : %s\n' % ( self.name, args ) )
-        self.sendCmd( *args, **kwargs )
-        return self.waitOutput( verbose )
+        if self.shell:
+            self.sendCmd( *args, **kwargs )
+            return self.waitOutput( verbose )
+        else:
+            warn( '(%s exited - ignoring cmd%s)\n' % ( self, args ) )
 
     def cmdPrint( self, *args):
         """Call cmd and printing its output