tests: Advertise FIB installed routes to bgp peers

Added test case for bgp suppress-fib-pending
Updated document

Signed-off-by: kssoman <somanks@gmail.com>

doc/user/bgp.rst

@@ -3412,6 +3412,48 @@ starting the daemon and the configuration gets saved, the option will persist
 unless removed from the configuration with the negating command prior to the
 configuration write operation.
 
+.. _bgp-suppress-fib:
+
+Suppressing routes not installed in FIB
+=======================================
+
+The FRR implementation of BGP advertises prefixes learnt from a peer to other
+peers even if the routes do not get installed in the FIB. There can be
+scenarios where the hardware tables in some of the routers (along the path from
+the source to destination) is full which will result in all routes not getting
+installed in the FIB. If these routes are advertised to the downstream routers
+then traffic will start flowing and will be dropped at the intermediate router.
+
+The solution is to provide a configurable option to check for the FIB install
+status of the prefixes and advertise to peers if the prefixes are successfully
+installed in the FIB. The advertisement of the prefixes are suppressed if it is
+not installed in FIB.
+
+The following conditions apply will apply when checking for route installation
+status in FIB:
+1. The advertisement or suppression of routes based on FIB install status
+   applies only for newly learnt routes from peer (routes which are not in
+   BGP local RIB).
+2. If the route received from peer already exists in BGP local RIB and route
+   attributes have changed (best path changed), the old path is deleted and
+   new path is installed in FIB. The FIB install status will not have any
+   effect. Therefore only when the route is received first time the checks
+   apply.
+3. The feature will not apply for routes learnt through other means like
+   redistribution to bgp from other protocols. This is applicable only to
+   peer learnt routes.
+4. If a route is installed in FIB and then gets deleted from the dataplane,
+   then routes will not be withdrawn from peers. This will be considered as
+   dataplane issue.
+5. The feature will slightly increase the time required to advertise the routes
+   to peers since the route install status needs to be received from the FIB
+6. If routes are received by the peer before the configuration is applied, then
+   the bgp sessions need to be reset for the configuration to take effect.
+7. If the route which is already installed in dataplane is removed for some
+   reason, sending withdraw message to peers is not currently supported.
+
+.. index:: [no] bgp suppress-fib-pending
+.. clicmd:: [no] bgp suppress-fib-pending
 
 .. _routing-policy:
 

tests/topotests/bgp_suppress_fib/r1/bgpd.conf

@@ -0,0 +1,15 @@
+! exit1
+router bgp 1
+  no bgp ebgp-requires-policy
+  neighbor 10.0.0.2 remote-as 2
+
+ address-family ipv4 unicast
+  redistribute static
+  neighbor 10.0.0.2 route-map rmap out
+ exit-address-family
+
+ip prefix-list plist seq 5 permit any
+
+route-map rmap permit 1
+  match ip address prefix-list plist
+!

tests/topotests/bgp_suppress_fib/r1/zebra.conf

@@ -0,0 +1,9 @@
+! exit1
+interface r1-eth0
+ ip address 10.0.0.1/30
+!
+ip forwarding
+!
+ip route 40.0.0.0/8 blackhole
+ip route 50.0.0.0/8 blackhole
+!

tests/topotests/bgp_suppress_fib/r2/bgpd.conf

@@ -0,0 +1,6 @@
+!
+router bgp 2
+  no bgp ebgp-requires-policy
+  bgp suppress-fib-pending
+  neighbor 10.0.0.1 remote-as 1
+  neighbor 10.0.0.10 remote-as 3

tests/topotests/bgp_suppress_fib/r2/zebra.conf

@@ -0,0 +1,13 @@
+!
+interface r2-eth0
+ ip address 10.0.0.2/30
+!
+interface r2-eth1
+ ip address 10.0.0.9/30
+
+access-list access seq 5 permit 40.0.0.0/8
+
+route-map LIMIT permit 10
+  match ip address access
+
+ip protocol bgp route-map LIMIT

tests/topotests/bgp_suppress_fib/r3/bgpd.conf

@@ -0,0 +1,9 @@
+!
+router bgp 3
+  no bgp ebgp-requires-policy
+  neighbor 10.0.0.9 remote-as 2
+
+route-map rmap permit 1
+  match ip address prefix-list plist
+  !
+!

tests/topotests/bgp_suppress_fib/r3/v4_route.json

@@ -0,0 +1,29 @@
+{
+  "40.0.0.0\/8":[
+    {
+      "prefix":"40.0.0.0\/8",
+      "protocol":"bgp",
+      "selected":true,
+      "destSelected":true,
+      "distance":20,
+      "metric":0,
+      "installed":true,
+      "table":254,
+      "internalStatus":16,
+      "internalFlags":8,
+      "internalNextHopNum":1,
+      "internalNextHopActiveNum":1,
+      "nexthops":[
+        {
+          "flags":3,
+          "fib":true,
+          "ip":"10.0.0.9",
+          "afi":"ipv4",
+          "interfaceIndex":2,
+          "interfaceName":"r3-eth0",
+          "active":true
+        }
+      ]
+    }
+  ]
+}

tests/topotests/bgp_suppress_fib/r3/v4_route2.json

@@ -0,0 +1,4 @@
+{
+  "0.0.0.0\/0":[
+  ]
+}

tests/topotests/bgp_suppress_fib/r3/zebra.conf

@@ -0,0 +1,6 @@
+!
+interface r3-eth0
+ ip address 10.0.0.10/30
+!
+ip forwarding
+!

tests/topotests/bgp_suppress_fib/test_bgp_suppress_fib.py

@@ -0,0 +1,119 @@
+#!/usr/bin/env python
+
+#
+# test_bgp_suppress_fib.py
+#
+# Copyright (c) 2019 by
+#
+# 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 time
+import pytest
+from functools import partial
+from time import sleep
+
+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
+
+
+class TemplateTopo(Topo):
+    def build(self, *_args, **_opts):
+        tgen = get_topogen(self)
+
+        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["r2"])
+        switch.add_link(tgen.gears["r3"])
+
+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_route():
+    tgen = get_topogen()
+
+    if tgen.routers_have_failure():
+        pytest.skip(tgen.errors)
+
+    r3 = tgen.gears["r3"]
+
+    sleep(5)
+
+    json_file = "{}/r3/v4_route.json".format(CWD)
+    expected = json.loads(open(json_file).read())
+
+    test_func = partial(
+        topotest.router_json_cmp,
+        r3,
+        "show ip route 40.0.0.0 json",
+        expected,
+    )
+    _, result = topotest.run_and_expect(test_func, None, count=2, wait=0.5)
+    assertmsg = '"r3" JSON output mismatches'
+    assert result is None, assertmsg
+
+    json_file = "{}/r3/v4_route2.json".format(CWD)
+    expected = json.loads(open(json_file).read())
+
+    test_func = partial(
+        topotest.router_json_cmp,
+        r3,
+        "show ip route 50.0.0.0 json",
+        expected,
+    )
+    _, result = topotest.run_and_expect(test_func, None, count=3, wait=0.5)
+    assertmsg = '"r3" JSON output mismatches'
+    assert result is None, assertmsg
+
+if __name__ == "__main__":
+    args = ["-s"] + sys.argv[1:]
+    sys.exit(pytest.main(args))