'Create pair of interfaces
intfname1: name of interface 1
intfname2: name of interface 2
(override this method [and possibly delete()]
to change link type)'

def makeIntfPair(self, intfname1, intfname2, addr1=None, addr2=None, node1=None, node2=None, deleteIntfs=True):

    node1 = (self.node1 if (node1 is None) else node1)
    node2 = (self.node2 if (node2 is None) else node2)
    server1 = getattr(node1, 'server', 'localhost')
    server2 = getattr(node2, 'server', 'localhost')
    if (server1 == server2):
        Link.makeIntfPair(intfname1, intfname2, addr1, addr2, node1, node2, deleteIntfs=deleteIntfs)
        node1.cmd(('ip    link    set    dev    %s    mtu    1450' % intfname1))
        node2.cmd(('ip    link    set    dev    %s    mtu    1450' % intfname2))
    else:
        self.makeTunnel(node1, node2, intfname1, intfname2, addr1, addr2)
        self.tunnel = 1
