tests: Add a test to ensure that the received NHG id works as expected

Add a simple test that does some basic exercising of the receivedNHGId
and that it worked as expected.

Signed-off-by: Donald Sharp <[email protected]>

Author: donaldsharp

tests/topotests/zebra_received_nhe_kept/r1/frr.conf

@@ -0,0 +1,14 @@
+!
+interface r1-eth0
+ ip address 192.168.1.1/24
+!
+!
+ip route 10.0.0.0/32 192.168.1.1
+ip route 10.0.0.1/32 10.0.0.0
+ip route 10.0.0.2/32 10.0.0.0
+ip route 10.0.0.3/32 10.0.0.0
+ip route 10.0.0.4/32 10.0.0.0
+ip route 10.0.0.5/32 10.0.0.0
+!
+line vty
+!

tests/topotests/zebra_received_nhe_kept/test_zebra_received_nhe_kept.py

@@ -0,0 +1,267 @@
+#!/usr/bin/env python
+# SPDX-License-Identifier: ISC
+
+#
+# test_zebra_received_nhe_kept.py
+#
+# Copyright (c) 2025 by Donald Sharp, Nvidia Inc.
+#
+
+"""
+test_zebra_received_nhe_kept.py: Test of Zebra Next Hop Entry Kept
+"""
+
+import os
+import sys
+import pytest
+import json
+from functools import partial
+
+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 lib.common_config import step
+
+def build_topo(tgen):
+    "Build function"
+
+    # Create router r1
+    tgen.add_router("r1")
+
+    # Create a switch to connect to r1's interface
+    switch = tgen.add_switch("s1")
+    switch.add_link(tgen.gears["r1"])
+
+
+def setup_module(mod):
+    "Sets up the pytest environment"
+    tgen = Topogen(build_topo, mod.__name__)
+    tgen.start_topology()
+
+    # For all registered routers, load the zebra configuration file
+    for rname, router in tgen.routers().items():
+        logger.info("Loading router %s" % rname)
+        router.load_frr_config(os.path.join(CWD, "{}/frr.conf".format(rname)))
+
+    # After loading the configurations, this function loads configured daemons.
+    tgen.start_router()
+
+
+def teardown_module():
+    "Teardown the pytest environment"
+    tgen = get_topogen()
+
+    # This function tears down the whole topology.
+    tgen.stop_topology()
+
+
+def test_zebra_received_nhe_kept():
+    "Test that zebra keeps received next hop entries"
+    tgen = get_topogen()
+    if tgen.routers_have_failure():
+        pytest.skip(tgen.errors)
+
+    r1 = tgen.gears["r1"]
+    
+    step("Get the route information")
+    # Get the route information
+    route_info = r1.vtysh_cmd("show ip route json")
+    route_json = json.loads(route_info)
+    
+    # Get the NHG ID for 10.0.0.1
+    nhg_id = None
+    for prefix, route in route_json.items():
+        if prefix == "10.0.0.1/32":
+            nhg_id = route[0].get("receivedNexthopGroupId")
+            break
+    
+    step("Verify all routes 10.0.0.1-.5 have the same NHG ID {}".format(nhg_id))
+    # Verify all routes 10.0.0.1-.5 have the same NHG ID
+    for i in range(1, 6):
+        prefix = f"10.0.0.{i}/32"
+        assert prefix in route_json, f"Route {prefix} not found"
+        route = route_json[prefix][0]
+        assert "receivedNexthopGroupId" in route, f"Route {prefix} missing receivedNexthopGroupId"
+        assert route["receivedNexthopGroupId"] == nhg_id, f"Route {prefix} has different NHG ID"
+
+    step("Verify NHG {} has refcount of 5".format(nhg_id))
+    # Get the NHG information
+    nhg_info = r1.vtysh_cmd("show nexthop-group rib {} json".format(nhg_id))
+    nhg_json = json.loads(nhg_info)
+    assert nhg_json[str(nhg_id)]["refCount"] == 5, "NHG refcount is not 5"
+
+
+def test_zebra_received_nhe_kept_remove_routes():
+    "Test that zebra updates refcount when routes are removed"
+    tgen = get_topogen()
+    if tgen.routers_have_failure():
+        pytest.skip(tgen.errors)
+
+    r1 = tgen.gears["r1"]
+    
+    step("Remove routes 10.0.0.3, 10.0.0.4, and 10.0.0.5")
+    # Remove the routes
+    for i in range(3, 6):
+        r1.vtysh_cmd("configure terminal\n no ip route 10.0.0.{}/32 10.0.0.0\n end".format(i))
+    
+    # Wait for zebra to process the route removals
+    def check_routes_removed():
+        route_info = r1.vtysh_cmd("show ip route json")
+        route_json = json.loads(route_info)
+        
+        # Check routes 10.0.0.1 and 10.0.0.2 exist
+        for i in range(1, 3):
+            prefix = f"10.0.0.{i}/32"
+            if prefix not in route_json:
+                return False
+        
+        # Check routes 10.0.0.3 through 10.0.0.5 don't exist
+        for i in range(3, 6):
+            prefix = f"10.0.0.{i}/32"
+            if prefix in route_json:
+                return False
+        
+        return True
+    
+    step("Wait for routes to be removed")
+    _, result = topotest.run_and_expect(check_routes_removed, True, count=30, wait=1)
+    assert result, "Routes were not properly removed"
+    
+    step("Get the route information")
+    # Get the route information
+    route_info = r1.vtysh_cmd("show ip route json")
+    route_json = json.loads(route_info)
+    
+    # Get the NHG ID for 10.0.0.1
+    nhg_id = None
+    for prefix, route in route_json.items():
+        if prefix == "10.0.0.1/32":
+            nhg_id = route[0].get("receivedNexthopGroupId")
+            break
+    
+    step("Verify NHG {} has refcount of 2".format(nhg_id))
+    # Get the NHG information
+    nhg_info = r1.vtysh_cmd("show nexthop-group rib {} json".format(nhg_id))
+    nhg_json = json.loads(nhg_info)
+    assert nhg_json[str(nhg_id)]["refCount"] == 2, "NHG refcount is not 2"
+
+
+def test_zebra_received_nhe_kept_add_routes():
+    "Test that zebra updates refcount when routes are added"
+    tgen = get_topogen()
+    if tgen.routers_have_failure():
+        pytest.skip(tgen.errors)
+
+    r1 = tgen.gears["r1"]
+    
+    step("Add routes 10.0.0.3 through 10.0.0.10")
+    # Add the routes
+    for i in range(3, 11):
+        r1.vtysh_cmd("configure terminal\n ip route 10.0.0.{}/32 10.0.0.0\n end".format(i))
+    
+    # Wait for zebra to process the route additions
+    def check_routes_added():
+        route_info = r1.vtysh_cmd("show ip route json")
+        route_json = json.loads(route_info)
+        
+        # Check all routes 10.0.0.1 through 10.0.0.10 exist
+        for i in range(1, 11):
+            prefix = f"10.0.0.{i}/32"
+            if prefix not in route_json:
+                return False
+            route = route_json[prefix][0]
+            if "receivedNexthopGroupId" not in route:
+                return False
+        
+        return True
+    
+    step("Wait for routes to be added")
+    _, result = topotest.run_and_expect(check_routes_added, True, count=30, wait=1)
+    assert result, "Routes were not properly added"
+    
+    step("Get the route information")
+    # Get the route information
+    route_info = r1.vtysh_cmd("show ip route json")
+    route_json = json.loads(route_info)
+    
+    # Get the NHG ID for 10.0.0.1
+    nhg_id = None
+    for prefix, route in route_json.items():
+        if prefix == "10.0.0.1/32":
+            nhg_id = route[0].get("receivedNexthopGroupId")
+            break
+    
+    step("Verify all routes 10.0.0.1-.10 have the same NHG ID {}".format(nhg_id))
+    # Verify all routes 10.0.0.1-.10 have the same NHG ID
+    for i in range(1, 11):
+        prefix = f"10.0.0.{i}/32"
+        assert prefix in route_json, f"Route {prefix} not found"
+        route = route_json[prefix][0]
+        assert "receivedNexthopGroupId" in route, f"Route {prefix} missing receivedNexthopGroupId"
+        assert route["receivedNexthopGroupId"] == nhg_id, f"Route {prefix} has different NHG ID"
+
+    step("Verify NHG {} has refcount of 10".format(nhg_id))
+    # Get the NHG information
+    nhg_info = r1.vtysh_cmd("show nexthop-group rib {} json".format(nhg_id))
+    nhg_json = json.loads(nhg_info)
+    assert nhg_json[str(nhg_id)]["refCount"] == 10, "NHG refcount is not 10"
+
+
+def test_zebra_received_nhe_kept_remove_all_routes():
+    "Test that zebra removes NHG when all routes are removed"
+    tgen = get_topogen()
+    if tgen.routers_have_failure():
+        pytest.skip(tgen.errors)
+
+    r1 = tgen.gears["r1"]
+    
+    step("Get the NHG ID before removing routes")
+    # Get the route information
+    route_info = r1.vtysh_cmd("show ip route 10.0.0.1/32 json")
+    route_json = json.loads(route_info)
+    
+    # Get the NHG ID for 10.0.0.1
+    nhg_id = None
+    for prefix, route in route_json.items():
+        if prefix == "10.0.0.1/32":
+            nhg_id = route[0].get("receivedNexthopGroupId")
+            break
+    
+    step("Remove all routes 10.0.0.1 through 10.0.0.10")
+    # Remove all routes
+    for i in range(1, 11):
+        r1.vtysh_cmd("configure terminal\n no ip route 10.0.0.{}/32 10.0.0.0\n end".format(i))
+    
+    # Wait for zebra to process the route removals
+    def check_all_routes_removed():
+        route_info = r1.vtysh_cmd("show ip route json")
+        route_json = json.loads(route_info)
+        
+        # Check no 10.0.0.x routes exist
+        for i in range(1, 11):
+            prefix = f"10.0.0.{i}/32"
+            if prefix in route_json:
+                return False
+        
+        return True
+    
+    step("Wait for all routes to be removed")
+    _, result = topotest.run_and_expect(check_all_routes_removed, True, count=30, wait=1)
+    assert result, "Routes were not properly removed"
+    
+    step("Get NHG information")
+    # Get all NHG information
+    nhg_info = r1.vtysh_cmd("show nexthop-group rib json")
+    nhg_json = json.loads(nhg_info)
+    
+    # Verify the specific NHG we looked up is no longer present
+    assert str(nhg_id) not in nhg_json, f"NHG {nhg_id} still exists after removing all routes"
+    
+
+if __name__ == "__main__":
+    args = ["-s"] + sys.argv[1:]
+    sys.exit(pytest.main(args))