def METHOD_NAME(tgen):
    "Build function"
    # Create 2 routers
    r1 = tgen.add_router("r1")
    r2 = tgen.add_router("r2")
    # Create a p2p connection between r1 and r2
    tgen.add_link(r1, r2)
    # Create a switch with one router connected to it to simulate a empty network.
    switch = tgen.add_switch("s1")
    switch.add_link(r1)
    # Create a p2p connection between r1 and r2
    switch = tgen.add_switch("s2")
    switch.add_link(r1)
    switch.add_link(r2)