def makeIntfPair( cls, intf1, intf2 ):
     """Create pair of interfaces
        intf1: name of interface 1
        intf2: name of interface 2
        (override this class method [and possibly delete()]
        to change link type)"""
     makeIntfPair( intf1, intf2  )

 def makeIntfPair(cls,
                  intfname1,
                  intfname2,
                  addr1=None,
                  addr2=None,
                  node1=None,
                  node2=None,
                  deleteIntfs=True):
     """Create pair of interfaces
        intfname1: name for interface 1
        intfname2: name for interface 2
        addr1: MAC address for interface 1 (optional)
        addr2: MAC address for interface 2 (optional)
        node1: home node for interface 1 (optional)
        node2: home node for interface 2 (optional)
        (override this method [and possibly delete()]
        to change link type)"""
     # Leave this as a class method for now
     assert cls
     return makeIntfPair(
         intfname1,
         intfname2,
         addr1,
         addr2,
         node1,
         node2,
         deleteIntfs=deleteIntfs)

 def makeIntfPair( _cls, intfname1, intfname2, addr1=None, addr2=None ):
     """Create pair of interfaces
        intfname1: name of interface 1
        intfname2: name of interface 2
        (override this method [and possibly delete()]
        to change link type)"""
     return makeIntfPair( intfname1, intfname2, addr1, addr2 )

 def makeIntfPair( cls, intfname1, intfname2, addr1=None, addr2=None ):
     """Create pair of interfaces
        intfname1: name of interface 1
        intfname2: name of interface 2
        (override this method [and possibly delete()]
        to change link type)"""
     # Leave this as a class method for now
     assert cls
     return makeIntfPair( intfname1, intfname2, addr1, addr2 )

 def linkTo( self, node2, port1=None, port2=None ):
     """Create link to another node, making two new interfaces.
        node2: Node to link us to
        port1: our port number (optional)
        port2: node2 port number (optional)
        returns: intf1 name, intf2 name"""
     node1 = self
     if port1 is None:
         port1 = node1.newPort()
     if port2 is None:
         port2 = node2.newPort()
     intf1 = node1.intfName( port1 )
     intf2 = node2.intfName( port2 )
     makeIntfPair( intf1, intf2 )
     node1.addIntf( intf1, port1 )
     node2.addIntf( intf2, port2 )
     node1.registerIntf( intf1, node2, intf2 )
     node2.registerIntf( intf2, node1, intf1 )
     return intf1, intf2

 def makeIntfPair( self, intfname1, intfname2, addr1=None, addr2=None ):
     """Create pair of interfaces
         intfname1: name of interface 1
         intfname2: name of interface 2
         (override this method [and possibly delete()]
         to change link type)"""
     node1, node2 = self.node1, self.node2
     server1 = getattr( node1, 'server', 'localhost' )
     server2 = getattr( node2, 'server', 'localhost' )
     if server1 == 'localhost' and server2 == 'localhost':
         # Local link
         return makeIntfPair( intfname1, intfname2, addr1, addr2 )
     elif server1 == server2:
         # Remote link on same remote server
         return makeIntfPair( intfname1, intfname2, addr1, addr2,
                              run=node1.rcmd )
     # Otherwise, make a tunnel
     self.tunnel = self.makeTunnel( node1, node2, intfname1, intfname2, addr1, addr2 )
     return self.tunnel