def METHOD_NAME():
    tgen = get_topogen()
    if tgen.routers_have_failure():
        pytest.skip(tgen.errors)
    def _bgp_converge():
        output = json.loads(
            tgen.gears["r2"].vtysh_cmd("show ip bgp 172.16.255.254/32 json")
        )
        expected = {"paths": [{"community": {"list": ["blackhole", "noExport"]}}]}
        return topotest.json_cmp(output, expected)
    def _bgp_no_advertise_ebgp():
        output = json.loads(
            tgen.gears["r2"].vtysh_cmd(
                "show ip bgp neighbor r2-eth1 advertised-routes json"
            )
        )
        expected = {
            "advertisedRoutes": {},
            "totalPrefixCounter": 0,
            "filteredPrefixCounter": 0,
        }
        return topotest.json_cmp(output, expected)
    def _bgp_no_advertise_ibgp():
        output = json.loads(
            tgen.gears["r2"].vtysh_cmd(
                "show ip bgp neighbor r2-eth2 advertised-routes json"
            )
        )
        expected = {
            "advertisedRoutes": {"172.16.255.254/32": {}},
            "totalPrefixCounter": 2,
        }
        return topotest.json_cmp(output, expected)
    def _bgp_verify_nexthop_validity():
        output = json.loads(tgen.gears["r4"].vtysh_cmd("show bgp nexthop json"))
        expected = {
            "ipv6": {
                "fe80::202:ff:fe00:99": {
                    "valid": True,
                    "complete": True,
                    "igpMetric": 0,
                    "pathCount": 2,
                    "nexthops": [{"interfaceName": "r4-eth0"}],
                },
            }
        }
        return topotest.json_cmp(output, expected)
    test_func = functools.partial(_bgp_converge)
    success, result = topotest.run_and_expect(test_func, None, count=60, wait=0.5)
    assert result is None, 'Failed bgp convergence in "{}"'.format(tgen.gears["r2"])
    step("Check if 172.16.255.254/32 is not advertised to eBGP peers")
    test_func = functools.partial(_bgp_no_advertise_ebgp)
    success, result = topotest.run_and_expect(test_func, None, count=60, wait=0.5)
    assert (
        result is None
    ), 'Advertised blackhole tagged prefix to eBGP peers in "{}"'.format(
        tgen.gears["r2"]
    )
    step("Check if 172.16.255.254/32 is advertised to iBGP peers")
    test_func = functools.partial(_bgp_no_advertise_ibgp)
    success, result = topotest.run_and_expect(test_func, None, count=60, wait=0.5)
    assert (
        result is None
    ), 'Withdrawn blackhole tagged prefix to iBGP peers in "{}"'.format(
        tgen.gears["r2"]
    )
    step("Verify if the nexthop set via route-map on r4 is marked valid")
    test_func = functools.partial(_bgp_verify_nexthop_validity)
    success, result = topotest.run_and_expect(test_func, None, count=60, wait=0.5)
    assert result is None, 'Nexthops are not valid "{}"'.format(tgen.gears["r4"])