public static String compactLinkString(Link link) {
        return String.format(COMPACT, link.src().elementId(), link.src().port(),
                link.dst().elementId(), link.dst().port());
    }
@Test
    public void linkStringFuBah() {
        String compact = TopoUtils.compactLinkString(LINK_FU_BAH);
        assertEquals("wrong link id", "fu:001/3-bah:002/5", compact);
    }