Merge pull request #17219 from zhou-run/202406201119

isisd: When the ISIS types of the routers do not match on a P2P link, the neighbor status remains UP

isisd/isis_pdu.c

@@ -231,7 +231,8 @@ static int process_p2p_hello(struct iih_info *iih)
 			return ISIS_OK;
 		}
 	}
-	if (!adj || adj->level != iih->calculated_type) {
+	if (!adj || adj->level != iih->calculated_type ||
+	    !(iih->circuit->is_type & iih->circ_type)) {
 		if (!adj) {
 			adj = isis_new_adj(iih->sys_id, NULL,
 					   iih->calculated_type, iih->circuit);

tests/topotests/isis_topo1/test_isis_topo1.py

@@ -12,6 +12,7 @@
 """
 test_isis_topo1.py: Test ISIS topology.
 """
+import time
 import datetime
 import functools
 import json
@@ -314,6 +315,107 @@ def test_isis_neighbor_json():
         ), assertmsg
 
 
+def test_isis_neighbor_state():
+    "Check that the neighbor states remain normal when the ISIS type is switched."
+
+    tgen = get_topogen()
+    # Don't run this test if we have any failure.
+    if tgen.routers_have_failure():
+        pytest.skip(tgen.errors)
+
+    logger.info("Checking 'show isis neighbor state on a p2p link'")
+
+    # Establish a P2P link
+    # When the IS-IS type of r3 is set to level-1-2 and the IS-IS type of r5 is set to level-1,
+    # it is expected that all neighbors exist and are in the Up state
+    r3 = tgen.gears["r3"]
+    r3.vtysh_cmd(
+        """
+        configure
+        router isis 1
+            no redistribute ipv4 connected level-1
+            no redistribute ipv4 connected level-2
+            no redistribute ipv6 connected level-1
+            no redistribute ipv6 connected level-2
+        interface r3-eth1
+            no isis circuit-type
+            isis network point-to-point
+        end
+        """
+    )
+    r5 = tgen.gears["r5"]
+    r5.vtysh_cmd(
+        """
+        configure
+        router isis 1
+            no redistribute ipv4 connected level-1
+            no redistribute ipv6 connected level-1
+            no redistribute ipv4 table 20 level-1
+        interface r5-eth0
+            no isis circuit-type
+            isis network point-to-point
+        end
+        """
+    )
+    result = _check_isis_neighbor_json("r3", "r5", True, "Up")
+    assert result is True, result
+    result = _check_isis_neighbor_json("r5", "r3", True, "Up")
+    assert result is True, result
+
+    # Remove the configuration that affects the switch of IS-IS type.
+    # Configure the IS-IS type of r3 to transition from level-1-2 to level-2-only,
+    # while maintaining the IS-IS type of r5 as level-1.
+    # In this scenario,
+    # the expectation is that some neighbors do not exist or are in the Initializing state
+    r3.vtysh_cmd(
+        """
+        configure
+        router isis 1
+            is-type level-2-only
+        end
+        """
+    )
+    result = _check_isis_neighbor_json("r3", "r5", False, "Initializing")
+    assert result is True, result
+    result = _check_isis_neighbor_json("r5", "r3", False, "Initializing")
+    assert result is True, result
+
+    # Restore to initial configuration
+    logger.info("Checking 'restore to initial configuration'")
+    r3.vtysh_cmd(
+        """
+        configure
+        interface r3-eth1
+            isis circuit-type level-1
+            no isis network point-to-point
+        router isis 1
+            no is-type
+            redistribute ipv4 connected level-1
+            redistribute ipv4 connected level-2
+            redistribute ipv6 connected level-1
+            redistribute ipv6 connected level-2
+        end
+        """
+    )
+    r5.vtysh_cmd(
+        """
+        configure
+        interface r5-eth0
+            isis circuit-type level-1
+            no isis network point-to-point
+        router isis 1
+            redistribute ipv4 connected level-1
+            redistribute ipv6 connected level-1
+            redistribute ipv4 table 20 level-1
+        end
+        """
+    )
+    result = _check_isis_neighbor_json("r3", "r5", True, "Up")
+    assert result is True, result
+    result = _check_isis_neighbor_json("r5", "r3", True, "Up")
+    assert result is True, result
+
+
 def test_isis_database_json():
     "Check json struct in show isis database json"
 
@@ -623,6 +725,65 @@ def test_isis_hello_padding_during_adjacency_formation():
     assert result is True, result
 
 
+def _check_isis_neighbor_json(
+    self, neighbor, neighbor_expected, neighbor_state_expected
+):
+    tgen = get_topogen()
+    router = tgen.gears[self]
+    logger.info(
+        f"check_isis_neighbor_json {router} {neighbor} {neighbor_expected} {neighbor_state_expected}"
+    )
+
+    result = _check_isis_neighbor_exist(self, neighbor)
+    if result == True:
+        return _check_isis_neighbor_state(self, neighbor, neighbor_state_expected)
+    elif neighbor_expected == True:
+        return "{} with expected neighbor {} got none ".format(router.name, neighbor)
+    else:
+        return True
+
+
+@retry(retry_timeout=60)
+def _check_isis_neighbor_exist(self, neighbor):
+    tgen = get_topogen()
+    router = tgen.gears[self]
+    logger.info(f"check_isis_neighbor_exist {router} {neighbor}")
+    neighbor_json = router.vtysh_cmd("show isis neighbor json", isjson=True)
+
+    circuits = neighbor_json.get("areas", [])[0].get("circuits", [])
+    for circuit in circuits:
+        if "adj" in circuit and circuit["adj"] == neighbor:
+            return True
+
+    return "The neighbor {} of router {} has not been learned yet ".format(
+        neighbor, router.name
+    )
+
+
+@retry(retry_timeout=5)
+def _check_isis_neighbor_state(self, neighbor, neighbor_state_expected):
+    tgen = get_topogen()
+    router = tgen.gears[self]
+    logger.info(
+        f"check_isis_neighbor_state {router} {neighbor} {neighbor_state_expected}"
+    )
+    neighbor_json = router.vtysh_cmd(
+        "show isis neighbor {} json".format(neighbor), isjson=True
+    )
+
+    circuits = neighbor_json.get("areas", [])[0].get("circuits", [])
+    for circuit in circuits:
+        interface = circuit.get("interface", {})
+        if "state" in interface:
+            neighbor_state = interface["state"]
+            if neighbor_state == neighbor_state_expected:
+                return True
+
+    return "{} peer with expected neighbor_state {} got {} ".format(
+        router.name, neighbor_state_expected, neighbor_state
+    )
+
+
 @retry(retry_timeout=10)
 def check_last_iih_packet_for_padding(router, expect_padding):
     logfilename = "{}/{}".format(router.gearlogdir, "isisd.log")