tests: add a bgp path selection topotest

Add a bgp path selection topotest to the IGP metric path selection.

Signed-off-by: Louis Scalbert <louis.scalbert@6wind.com>

tests/topotests/bgp_path_selection/r1/bgpd.conf

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+router bgp 65001
+ no bgp ebgp-requires-policy
+ neighbor 192.0.2.2 remote-as 65002
+ neighbor 192.0.2.2 timers 1 3
+ neighbor 192.0.2.2 timers connect 1
+ neighbor 192.0.2.2 ebgp-multihop 2
+ neighbor 192.0.2.3 remote-as 65002
+ neighbor 192.0.2.3 timers 1 3
+ neighbor 192.0.2.3 timers connect 1
+ neighbor 192.0.2.3 ebgp-multihop 2
+ address-family ipv4
+  redistribute connected
+ exit-address-family
+ address-family ipv4 vpn
+  neighbor 192.0.2.2 activate
+  neighbor 192.0.2.3 activate
+ exit-address-family
+!
+router bgp 65001 vrf vrf1
+ bgp router-id 192.0.2.1
+ address-family ipv4 unicast
+  label vpn export 101
+  rd vpn export 101:1
+  rt vpn both 52:100
+  import vpn
+  export vpn
+ exit-address-family
+!

tests/topotests/bgp_path_selection/r1/ldpd.conf

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+hostname r1
+log file ldpd.log
+password zebra
+!
+! debug mpls ldp zebra
+! debug mpls ldp event
+! debug mpls ldp errors
+! debug mpls ldp messages recv
+! debug mpls ldp messages sent
+! debug mpls ldp discovery hello recv
+! debug mpls ldp discovery hello sent
+!
+mpls ldp
+ router-id 192.0.2.1
+ !
+ address-family ipv4
+  discovery transport-address 192.0.2.1
+  !
+  interface r1-eth0
+  !
+  interface r1-eth1
+  !
+ !
+!
+line vty
+!

tests/topotests/bgp_path_selection/r1/staticd.conf

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+ip route 192.0.2.2/32 192.168.1.2
+ip route 192.0.2.3/32 192.168.2.2

tests/topotests/bgp_path_selection/r1/zebra.conf

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+!
+interface lo
+ ip address 192.0.2.1/32
+ ip address 172.16.255.1/32
+!
+interface r1-eth0
+ ip address 192.168.1.1/24
+!
+interface r1-eth1
+ ip address 192.168.2.1/24
+!

tests/topotests/bgp_path_selection/r2/bgpd.conf

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+router bgp 65002
+ no bgp network import-check
+ network 192.0.2.8/32
+ no bgp ebgp-requires-policy
+ neighbor 192.168.1.1 remote-as 65001
+ neighbor 192.168.1.1 timers 1 3
+ neighbor 192.168.1.1 timers connect 1
+ neighbor 192.168.1.1 ebgp-multihop 2
+ neighbor 192.168.1.1 update-source 192.0.2.2
+ address-family ipv4 vpn
+  neighbor 192.168.1.1 activate
+ exit-address-family
+!
+router bgp 65002 vrf vrf1
+ bgp router-id 192.0.2.2
+ no bgp ebgp-requires-policy
+ address-family ipv4 unicast
+  redistribute connected
+  label vpn export 102
+  rd vpn export 102:1
+  rt vpn both 52:100
+  import vpn
+  export vpn
+ exit-address-family
+!

tests/topotests/bgp_path_selection/r2/ldpd.conf

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+hostname r2
+log file ldpd.log
+password zebra
+!
+! debug mpls ldp zebra
+! debug mpls ldp event
+! debug mpls ldp errors
+! debug mpls ldp messages recv
+! debug mpls ldp messages sent
+! debug mpls ldp discovery hello recv
+! debug mpls ldp discovery hello sent
+!
+mpls ldp
+ router-id 192.0.2.2
+ !
+ address-family ipv4
+  discovery transport-address 192.0.2.2
+  !
+  interface r2-eth0
+  !
+  interface r2-eth1
+  !
+ !
+!
+line vty
+!

tests/topotests/bgp_path_selection/r2/zebra.conf

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+!
+int lo
+ ip address 192.0.2.2/32
+!
+interface r2-eth0
+ ip address 192.168.1.2/24
+!

tests/topotests/bgp_path_selection/r3/bgpd.conf

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+router bgp 65002
+ no bgp network import-check
+ network 192.0.2.8/32
+ no bgp ebgp-requires-policy
+ neighbor 192.168.2.1 remote-as 65001
+ neighbor 192.168.2.1 timers 1 3
+ neighbor 192.168.2.1 timers connect 1
+ neighbor 192.168.2.1 ebgp-multihop 2
+ neighbor 192.168.1.1 update-source 192.0.2.3
+ address-family ipv4 vpn
+  neighbor 192.168.2.1 activate
+ exit-address-family
+!
+router bgp 65002 vrf vrf1
+ bgp router-id 192.0.2.3
+ no bgp ebgp-requires-policy
+ address-family ipv4 unicast
+  redistribute connected
+  label vpn export 103
+  rd vpn export 102:1
+  rt vpn both 52:100
+  import vpn
+  export vpn
+ exit-address-family
+!

tests/topotests/bgp_path_selection/r3/ldpd.conf

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+hostname r3
+password zebra
+log file ldpd.log
+!
+! debug mpls ldp zebra
+! debug mpls ldp event
+! debug mpls ldp errors
+! debug mpls ldp messages recv
+! debug mpls ldp messages sent
+! debug mpls ldp discovery hello recv
+! debug mpls ldp discovery hello sent
+!
+mpls ldp
+ router-id 192.0.2.3
+ !
+ address-family ipv4
+  discovery transport-address 192.0.2.3
+  !
+  interface r3-eth0
+  !
+ !
+!
+line vty
+!

tests/topotests/bgp_path_selection/r3/zebra.conf

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+!
+int lo
+ ip address 192.0.2.3/32
+!
+interface r3-eth0
+ ip address 192.168.2.2/24
+!

tests/topotests/bgp_path_selection/test_bgp_path_selection.py

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+#!/usr/bin/env python
+
+#
+# Copyright (c) 2022 by
+# Louis Scalbert <louis.scalbert@6wind.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.
+#
+
+"""
+
+"""
+
+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.common_config import step
+
+pytestmark = [pytest.mark.bgpd]
+
+
+def build_topo(tgen):
+    for routern in range(1, 4):
+        tgen.add_router("r{}".format(routern))
+
+    switch = tgen.add_switch("s1")
+    switch.add_link(tgen.gears["r1"])
+    switch.add_link(tgen.gears["r2"])
+
+    switch = tgen.add_switch("s2")
+    switch.add_link(tgen.gears["r1"])
+    switch.add_link(tgen.gears["r3"])
+
+
+def setup_module(mod):
+    tgen = Topogen(build_topo, mod.__name__)
+    tgen.start_topology()
+
+    router_list = tgen.routers()
+
+    for routern in range(1, 4):
+        tgen.gears["r{}".format(routern)].cmd("ip link add vrf1 type vrf table 10")
+        tgen.gears["r{}".format(routern)].cmd("ip link set vrf1 up")
+        tgen.gears["r{}".format(routern)].cmd("ip address add dev vrf1 {}.{}.{}.{}/32".format(routern, routern, routern,routern))
+    tgen.gears["r2"].cmd("ip address add dev vrf1 192.0.2.8/32")
+    tgen.gears["r3"].cmd("ip address add dev vrf1 192.0.2.8/32")
+
+    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))
+        )
+        router.load_config(
+            TopoRouter.RD_LDP, os.path.join(CWD, "{}/ldpd.conf".format(rname))
+        )
+
+    tgen.start_router()
+
+    tgen.gears["r1"].cmd("ip route add 192.0.2.2 via 192.168.1.2 metric 20")
+    tgen.gears["r1"].cmd("ip route add 192.0.2.3 via 192.168.2.2 metric 20")
+
+
+def teardown_module(mod):
+    tgen = get_topogen()
+    tgen.stop_topology()
+
+def test_bgp_path_selection_ecmp():
+    tgen = get_topogen()
+
+    if tgen.routers_have_failure():
+        pytest.skip(tgen.errors)
+
+    def _bgp_check_path_selection_ecmp():
+        output = json.loads(
+            tgen.gears["r1"].vtysh_cmd("show bgp ipv4 unicast 192.0.2.8/32 json")
+        )
+        expected = {
+            "paths": [
+                {
+                    "valid": True,
+                    "aspath": {"string": "65002"},
+                    "multipath": True,
+                    "nexthops": [{"ip": "192.0.2.2", "metric": 20}],
+                },
+                {
+                    "valid": True,
+                    "aspath": {"string": "65002"},
+                    "multipath": True,
+                    "nexthops": [{"ip": "192.0.2.3", "metric": 20}],
+                }
+            ]
+        }
+
+        return topotest.json_cmp(output, expected)
+
+    step("Check if two ECMP paths are present")
+    test_func = functools.partial(_bgp_check_path_selection_ecmp)
+    _, result = topotest.run_and_expect(test_func, None, count=60, wait=0.5)
+    assert result is None, "Failed to see BGP prefixes on R1"
+
+
+def test_bgp_path_selection_vpn_ecmp():
+    tgen = get_topogen()
+
+    if tgen.routers_have_failure():
+        pytest.skip(tgen.errors)
+
+    def _bgp_check_path_selection_vpn_ecmp():
+        output = json.loads(
+            tgen.gears["r1"].vtysh_cmd("show bgp vrf vrf1 ipv4 unicast 192.0.2.8/32 json")
+        )
+        expected = {
+            "paths": [
+                {
+                    "valid": True,
+                    "aspath": {"string": "65002"},
+                    "multipath": True,
+                    "nexthops": [{"ip": "192.0.2.2", "metric": 20}],
+                },
+                {
+                    "valid": True,
+                    "aspath": {"string": "65002"},
+                    "multipath": True,
+                    "nexthops": [{"ip": "192.0.2.3", "metric": 20}],
+                }
+            ]
+        }
+
+        return topotest.json_cmp(output, expected)
+
+    step("Check if two ECMP paths are present")
+    test_func = functools.partial(_bgp_check_path_selection_vpn_ecmp)
+    _, result = topotest.run_and_expect(test_func, None, count=60, wait=0.5)
+    assert result is None, "Failed to see BGP prefixes on R1"
+
+
+def test_bgp_path_selection_metric():
+    tgen = get_topogen()
+
+    if tgen.routers_have_failure():
+        pytest.skip(tgen.errors)
+
+    def _bgp_check_path_selection_metric():
+        output = json.loads(
+            tgen.gears["r1"].vtysh_cmd("show bgp ipv4 unicast 192.0.2.8/32 json")
+        )
+        expected = {
+            "paths": [
+                {
+                    "valid": True,
+                    "aspath": {"string": "65002"},
+                    "nexthops": [{"ip": "192.0.2.2", "metric": 10}],
+                    "bestpath":{ "selectionReason":"IGP Metric"},
+                },
+                {
+                    "valid": True,
+                    "aspath": {"string": "65002"},
+                    "nexthops": [{"ip": "192.0.2.3", "metric": 20}],
+                }
+            ]
+        }
+
+        return topotest.json_cmp(output, expected)
+
+    tgen.gears["r1"].cmd("ip route add 192.0.2.2 via 192.168.1.2 metric 10")
+    tgen.gears["r1"].cmd("ip route del 192.0.2.2 via 192.168.1.2 metric 20")
+
+    step("Check if IGP metric best path is selected")
+    test_func = functools.partial(_bgp_check_path_selection_metric)
+    _, result = topotest.run_and_expect(test_func, None, count=60, wait=0.5)
+    assert result is None, "Failed to see BGP prefixes on R1"
+
+
+def test_bgp_path_selection_vpn_metric():
+    tgen = get_topogen()
+
+    if tgen.routers_have_failure():
+        pytest.skip(tgen.errors)
+
+    def _bgp_check_path_selection_vpn_metric():
+        output = json.loads(
+            tgen.gears["r1"].vtysh_cmd("show bgp vrf vrf1 ipv4 unicast 192.0.2.8/32 json")
+        )
+        expected = {
+            "paths": [
+                {
+                    "valid": True,
+                    "aspath": {"string": "65002"},
+                    "nexthops": [{"ip": "192.0.2.2", "metric": 10}],
+                    "bestpath":{ "selectionReason":"IGP Metric"},
+                },
+                {
+                    "valid": True,
+                    "aspath": {"string": "65002"},
+                    "nexthops": [{"ip": "192.0.2.3", "metric": 20}],
+                }
+            ]
+        }
+
+        return topotest.json_cmp(output, expected)
+
+    step("Check if IGP metric best path is selected")
+    test_func = functools.partial(_bgp_check_path_selection_vpn_metric)
+    _, result = topotest.run_and_expect(test_func, None, count=60, wait=0.5)
+    assert result is None, "Failed to see BGP prefixes on R1"
+
+
+if __name__ == "__main__":
+    args = ["-s"] + sys.argv[1:]
+    sys.exit(pytest.main(args))