--- /dev/null
+#!/usr/bin/env python
+
+# Copyright (c) 2020 by
+# Donatas Abraitis <donatas.abraitis@gmail.com>
+#
+# Permission to use, copy, modify, and/or distribute this software
+# for any purpose with or without fee is hereby granted, provided
+# that the above copyright notice and this permission notice appear
+# in all copies.
+#
+# THE SOFTWARE IS PROVIDED "AS IS" AND NETDEF DISCLAIMS ALL WARRANTIES
+# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL NETDEF BE LIABLE FOR
+# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY
+# DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
+# WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
+# ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
+# OF THIS SOFTWARE.
+#
+
+"""
+Reference: https://www.cmand.org/communityexploration
+
+ --y2--
+ / | \
+ c1 ---- x1 ---- y1 | z1
+ \ | /
+ --y3--
+
+1. z1 announces 192.168.255.254/32 to y2, y3.
+2. y2 and y3 tags this prefix at ingress with appropriate
+communities 65004:2 (y2) and 65004:3 (y3).
+3. x1 filters all communities at the egress to c1.
+4. Shutdown the link between y1 and y2.
+5. y1 will generate a BGP UPDATE message regarding the next-hop change.
+6. x1 will generate a BGP UPDATE message regarding community change.
+
+To avoid sending duplicate BGP UPDATE messages we should make sure
+we send only actual route updates. In this example, x1 will skip
+BGP UPDATE to c1 because the actual route is the same
+(filtered communities - nothing changes).
+"""
+
+import os
+import sys
+import json
+import pytest
+import functools
+
+CWD = os.path.dirname(os.path.realpath(__file__))
+sys.path.append(os.path.join(CWD, "../"))
+
+# pylint: disable=C0413
+from lib import topotest
+from lib.topogen import Topogen, TopoRouter, get_topogen
+from lib.topolog import logger
+from mininet.topo import Topo
+
+from lib.common_config import step
+from time import sleep
+
+
+class TemplateTopo(Topo):
+ def build(self, *_args, **_opts):
+ tgen = get_topogen(self)
+
+ tgen.add_router("z1")
+ tgen.add_router("y1")
+ tgen.add_router("y2")
+ tgen.add_router("y3")
+ tgen.add_router("x1")
+ tgen.add_router("c1")
+
+ # 10.0.1.0/30
+ switch = tgen.add_switch("s1")
+ switch.add_link(tgen.gears["c1"])
+ switch.add_link(tgen.gears["x1"])
+
+ # 10.0.2.0/30
+ switch = tgen.add_switch("s2")
+ switch.add_link(tgen.gears["x1"])
+ switch.add_link(tgen.gears["y1"])
+
+ # 10.0.3.0/30
+ switch = tgen.add_switch("s3")
+ switch.add_link(tgen.gears["y1"])
+ switch.add_link(tgen.gears["y2"])
+
+ # 10.0.4.0/30
+ switch = tgen.add_switch("s4")
+ switch.add_link(tgen.gears["y1"])
+ switch.add_link(tgen.gears["y3"])
+
+ # 10.0.5.0/30
+ switch = tgen.add_switch("s5")
+ switch.add_link(tgen.gears["y2"])
+ switch.add_link(tgen.gears["y3"])
+
+ # 10.0.6.0/30
+ switch = tgen.add_switch("s6")
+ switch.add_link(tgen.gears["y2"])
+ switch.add_link(tgen.gears["z1"])
+
+ # 10.0.7.0/30
+ switch = tgen.add_switch("s7")
+ switch.add_link(tgen.gears["y3"])
+ switch.add_link(tgen.gears["z1"])
+
+
+def setup_module(mod):
+ tgen = Topogen(TemplateTopo, mod.__name__)
+ tgen.start_topology()
+
+ router_list = tgen.routers()
+
+ for i, (rname, router) in enumerate(router_list.items(), 1):
+ router.load_config(
+ TopoRouter.RD_ZEBRA, os.path.join(CWD, "{}/zebra.conf".format(rname))
+ )
+ router.load_config(
+ TopoRouter.RD_BGP, os.path.join(CWD, "{}/bgpd.conf".format(rname))
+ )
+
+ tgen.start_router()
+
+
+def teardown_module(mod):
+ tgen = get_topogen()
+ tgen.stop_topology()
+
+
+def test_bgp_community_update_path_change():
+ tgen = get_topogen()
+
+ if tgen.routers_have_failure():
+ pytest.skip(tgen.errors)
+
+ def _bgp_converge_initial():
+ output = json.loads(
+ tgen.gears["c1"].vtysh_cmd("show ip bgp neighbor 10.0.1.2 json")
+ )
+ expected = {
+ "10.0.1.2": {
+ "bgpState": "Established",
+ "addressFamilyInfo": {"ipv4Unicast": {"acceptedPrefixCounter": 8}},
+ }
+ }
+ return topotest.json_cmp(output, expected)
+
+ step("Check if an initial topology is converged")
+ test_func = functools.partial(_bgp_converge_initial)
+ success, result = topotest.run_and_expect(test_func, None, count=60, wait=0.5)
+ assert result is None, "Failed to see bgp convergence in c1"
+
+ step("Disable link between y1 and y2")
+ tgen.gears["y1"].run("ip link set dev y1-eth1 down")
+
+ def _bgp_converge_link_disabled():
+ output = json.loads(tgen.gears["y1"].vtysh_cmd("show ip bgp nei 10.0.3.2 json"))
+ expected = {"10.0.3.2": {"bgpState": "Active"}}
+ return topotest.json_cmp(output, expected)
+
+ step("Check if a topology is converged after a link down between y1 and y2")
+ test_func = functools.partial(_bgp_converge_link_disabled)
+ success, result = topotest.run_and_expect(test_func, None, count=60, wait=0.5)
+ assert result is None, "Failed to see bgp convergence in y1"
+
+ def _bgp_check_for_duplicate_updates():
+ duplicate = False
+ i = 0
+ while i < 5:
+ if (
+ len(
+ tgen.gears["c1"].run(
+ 'grep "10.0.1.2 rcvd 192.168.255.254/32 IPv4 unicast...duplicate ignored" bgpd.log'
+ )
+ )
+ > 0
+ ):
+ duplicate = True
+ i += 1
+ sleep(0.5)
+ return duplicate
+
+ step("Check if we see duplicate BGP UPDATE message in c1 (suppress-duplicates)")
+ assert (
+ _bgp_check_for_duplicate_updates() == False
+ ), "Seen duplicate BGP UPDATE message in c1 from x1"
+
+ step("Disable bgp suppress-duplicates at x1")
+ tgen.gears["x1"].run(
+ "vtysh -c 'conf' -c 'router bgp' -c 'no bgp suppress-duplicates'"
+ )
+
+ step("Enable link between y1 and y2")
+ tgen.gears["y1"].run("ip link set dev y1-eth1 up")
+
+ def _bgp_converge_link_enabled():
+ output = json.loads(tgen.gears["y1"].vtysh_cmd("show ip bgp nei 10.0.3.2 json"))
+ expected = {
+ "10.0.3.2": {
+ "bgpState": "Established",
+ "addressFamilyInfo": {
+ "ipv4Unicast": {"acceptedPrefixCounter": 5, "sentPrefixCounter": 4}
+ },
+ }
+ }
+ return topotest.json_cmp(output, expected)
+
+ step("Check if a topology is converged after a link up between y1 and y2")
+ test_func = functools.partial(_bgp_converge_link_enabled)
+ success, result = topotest.run_and_expect(test_func, None, count=60, wait=0.5)
+ assert result is None, "Failed to see bgp convergence in y1"
+
+ step(
+ "Check if we see duplicate BGP UPDATE message in c1 (no bgp suppress-duplicates)"
+ )
+ assert (
+ _bgp_check_for_duplicate_updates() == True
+ ), "Didn't see duplicate BGP UPDATE message in c1 from x1"
+
+
+if __name__ == "__main__":
+ args = ["-s"] + sys.argv[1:]
+ sys.exit(pytest.main(args))
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