Merge pull request #14528 from opensourcerouting/feature/bgpd_handle_addpath_capability_via_dynamic_capability

bgpd: Handle Addpath capability using dynamic capabilities

bgpd/bgp_addpath.c

@@ -10,6 +10,8 @@
 
 #include "bgp_addpath.h"
 #include "bgp_route.h"
+#include "bgp_open.h"
+#include "bgp_packet.h"
 
 static const struct bgp_addpath_strategy_names strat_names[BGP_ADDPATH_MAX] = {
 	{
@@ -359,6 +361,31 @@ void bgp_addpath_type_changed(struct bgp *bgp)
 	}
 }
 
+int bgp_addpath_capability_action(enum bgp_addpath_strat addpath_type,
+				  uint8_t paths)
+{
+	int action = CAPABILITY_ACTION_UNSET;
+
+	switch (addpath_type) {
+	case BGP_ADDPATH_ALL:
+	case BGP_ADDPATH_BEST_PER_AS:
+		action = CAPABILITY_ACTION_SET;
+		break;
+	case BGP_ADDPATH_BEST_SELECTED:
+		if (paths)
+			action = CAPABILITY_ACTION_SET;
+		else
+			action = CAPABILITY_ACTION_UNSET;
+		break;
+	case BGP_ADDPATH_NONE:
+	case BGP_ADDPATH_MAX:
+		action = CAPABILITY_ACTION_UNSET;
+		break;
+	}
+
+	return action;
+}
+
 /*
  * Change the addpath type assigned to a peer, or peer group. In addition to
  * adjusting the counts, peer sessions will be reset as needed to make the
@@ -373,6 +400,7 @@ void bgp_addpath_set_peer_type(struct peer *peer, afi_t afi, safi_t safi,
 	struct listnode *node, *nnode;
 	struct peer *tmp_peer;
 	struct peer_group *group;
+	int action = bgp_addpath_capability_action(addpath_type, paths);
 
 	if (safi == SAFI_LABELED_UNICAST)
 		safi = SAFI_UNICAST;
@@ -430,9 +458,12 @@ void bgp_addpath_set_peer_type(struct peer *peer, afi_t afi, safi_t safi,
 			}
 		}
 	} else {
-		peer_change_action(peer, afi, safi, peer_change_reset);
+		if (!CHECK_FLAG(peer->cap, PEER_CAP_DYNAMIC_RCV) &&
+		    !CHECK_FLAG(peer->cap, PEER_CAP_DYNAMIC_ADV))
+			peer_change_action(peer, afi, safi, peer_change_reset);
 	}
 
+	bgp_capability_send(peer, afi, safi, CAPABILITY_CODE_ADDPATH, action);
 }
 
 /*

bgpd/bgp_addpath.h

@@ -15,6 +15,12 @@
 #include "bgpd/bgp_table.h"
 #include "lib/json.h"
 
+struct bgp_addpath_capability {
+	uint16_t afi;
+	uint8_t safi;
+	uint8_t flags;
+};
+
 #define BGP_ADDPATH_TX_ID_FOR_DEFAULT_ORIGINATE 1
 
 void bgp_addpath_init_bgp_data(struct bgp_addpath_bgp_data *d);
@@ -57,4 +63,6 @@ void bgp_addpath_update_ids(struct bgp *bgp, struct bgp_dest *dest, afi_t afi,
 			    safi_t safi);
 
 void bgp_addpath_type_changed(struct bgp *bgp);
+extern int bgp_addpath_capability_action(enum bgp_addpath_strat addpath_type,
+					 uint8_t paths);
 #endif

bgpd/bgp_open.c

@@ -682,15 +682,17 @@ static int bgp_capability_addpath(struct peer *peer,
 		uint8_t send_receive = stream_getc(s);
 
 		if (bgp_debug_neighbor_events(peer))
-			zlog_debug(
+			zlog_debug("%s OPEN has %s capability for afi/safi: %s/%s%s%s",
-				"%s OPEN has %s capability for afi/safi: %s/%s%s%s",
+				   peer->host,
-				peer->host,
+				   lookup_msg(capcode_str, hdr->code, NULL),
-				lookup_msg(capcode_str, hdr->code, NULL),
+				   iana_afi2str(pkt_afi),
-				iana_afi2str(pkt_afi), iana_safi2str(pkt_safi),
+				   iana_safi2str(pkt_safi),
-				(send_receive & BGP_ADDPATH_RX) ? ", receive"
+				   CHECK_FLAG(send_receive, BGP_ADDPATH_RX)
-								: "",
+					   ? ", receive"
-				(send_receive & BGP_ADDPATH_TX) ? ", transmit"
+					   : "",
-								: "");
+				   CHECK_FLAG(send_receive, BGP_ADDPATH_TX)
+					   ? ", transmit"
+					   : "");
 
 		/* Convert AFI, SAFI to internal values, check. */
 		if (bgp_map_afi_safi_iana2int(pkt_afi, pkt_safi, &afi, &safi)) {
@@ -709,13 +711,19 @@ static int bgp_capability_addpath(struct peer *peer,
 			continue;
 		}
 
-		if (send_receive & BGP_ADDPATH_RX)
+		if (CHECK_FLAG(send_receive, BGP_ADDPATH_RX))
 			SET_FLAG(peer->af_cap[afi][safi],
 				 PEER_CAP_ADDPATH_AF_RX_RCV);
+		else
+			UNSET_FLAG(peer->af_cap[afi][safi],
+				   PEER_CAP_ADDPATH_AF_RX_RCV);
 
-		if (send_receive & BGP_ADDPATH_TX)
+		if (CHECK_FLAG(send_receive, BGP_ADDPATH_TX))
 			SET_FLAG(peer->af_cap[afi][safi],
 				 PEER_CAP_ADDPATH_AF_TX_RCV);
+		else
+			UNSET_FLAG(peer->af_cap[afi][safi],
+				   PEER_CAP_ADDPATH_AF_TX_RCV);
 	}
 
 	return 0;

bgpd/bgp_packet.c

@@ -24,6 +24,7 @@
 #include "lib_errors.h"
 
 #include "bgpd/bgpd.h"
+#include "bgpd/bgp_addpath.h"
 #include "bgpd/bgp_table.h"
 #include "bgpd/bgp_dump.h"
 #include "bgpd/bgp_bmp.h"
@@ -1211,6 +1212,8 @@ void bgp_capability_send(struct peer *peer, afi_t afi, safi_t safi,
 	unsigned long cap_len;
 	uint16_t len;
 	uint32_t gr_restart_time;
+	uint8_t addpath_afi_safi_count = 0;
+	bool adv_addpath_tx = false;
 	const char *capability = lookup_msg(capcode_str, capability_code,
 					    "Unknown");
 
@@ -1374,11 +1377,91 @@ void bgp_capability_send(struct peer *peer, afi_t afi, safi_t safi,
 				   capability, iana_afi2str(pkt_afi),
 				   iana_safi2str(pkt_safi));
 		break;
+	case CAPABILITY_CODE_ADDPATH:
+		SET_FLAG(peer->cap, PEER_CAP_ADDPATH_ADV);
+
+		FOREACH_AFI_SAFI (afi, safi) {
+			if (peer->afc[afi][safi]) {
+				addpath_afi_safi_count++;
+
+				/* Only advertise addpath TX if a feature that
+				* will use it is
+				* configured */
+				if (peer->addpath_type[afi][safi] !=
+				    BGP_ADDPATH_NONE)
+					adv_addpath_tx = true;
+
+				/* If we have enabled labeled unicast, we MUST check
+				* against unicast SAFI because addpath IDs are
+				* allocated under unicast SAFI, the same as the RIB
+				* is managed in unicast SAFI.
+				*/
+				if (safi == SAFI_LABELED_UNICAST)
+					if (peer->addpath_type[afi][SAFI_UNICAST] !=
+					    BGP_ADDPATH_NONE)
+						adv_addpath_tx = true;
+			}
+		}
+
+		stream_putc(s, action);
+		stream_putc(s, CAPABILITY_CODE_ADDPATH);
+		stream_putc(s, CAPABILITY_CODE_ADDPATH_LEN *
+				       addpath_afi_safi_count);
+
+		FOREACH_AFI_SAFI (afi, safi) {
+			if (peer->afc[afi][safi]) {
+				bool adv_addpath_rx =
+					!CHECK_FLAG(peer->af_flags[afi][safi],
+						    PEER_FLAG_DISABLE_ADDPATH_RX);
+				uint8_t flags = 0;
+
+				/* Convert AFI, SAFI to values for packet. */
+				bgp_map_afi_safi_int2iana(afi, safi, &pkt_afi,
+							  &pkt_safi);
+
+				stream_putw(s, pkt_afi);
+				stream_putc(s, pkt_safi);
+
+				if (adv_addpath_rx) {
+					SET_FLAG(flags, BGP_ADDPATH_RX);
+					SET_FLAG(peer->af_cap[afi][safi],
+						 PEER_CAP_ADDPATH_AF_RX_ADV);
+				} else {
+					UNSET_FLAG(peer->af_cap[afi][safi],
+						   PEER_CAP_ADDPATH_AF_RX_ADV);
+				}
+
+				if (adv_addpath_tx) {
+					SET_FLAG(flags, BGP_ADDPATH_TX);
+					SET_FLAG(peer->af_cap[afi][safi],
+						 PEER_CAP_ADDPATH_AF_TX_ADV);
+					if (safi == SAFI_LABELED_UNICAST)
+						SET_FLAG(peer->af_cap[afi]
+								     [SAFI_UNICAST],
+							 PEER_CAP_ADDPATH_AF_TX_ADV);
+				} else {
+					UNSET_FLAG(peer->af_cap[afi][safi],
+						   PEER_CAP_ADDPATH_AF_TX_ADV);
+				}
+
+				stream_putc(s, flags);
+			}
+		}
+
+		if (bgp_debug_neighbor_events(peer))
+			zlog_debug("%pBP sending CAPABILITY has %s %s for afi/safi: %s/%s",
+				   peer,
+				   action == CAPABILITY_ACTION_SET
+					   ? "Advertising"
+					   : "Removing",
+				   capability, iana_afi2str(pkt_afi),
+				   iana_safi2str(pkt_safi));
+
+		break;
 	case CAPABILITY_CODE_REFRESH:
 	case CAPABILITY_CODE_ORF:
 	case CAPABILITY_CODE_AS4:
 	case CAPABILITY_CODE_DYNAMIC:
-	case CAPABILITY_CODE_ADDPATH:
 	case CAPABILITY_CODE_ENHANCED_RR:
 	case CAPABILITY_CODE_FQDN:
 	case CAPABILITY_CODE_ENHE:
@@ -2871,6 +2954,96 @@ static int bgp_route_refresh_receive(struct peer_connection *connection,
 	return BGP_PACKET_NOOP;
 }
 
+static void bgp_dynamic_capability_addpath(uint8_t *pnt, int action,
+					   struct capability_header *hdr,
+					   struct peer *peer)
+{
+	uint8_t *data = pnt + 3;
+	uint8_t *end = data + hdr->length;
+	size_t len = end - data;
+	afi_t afi;
+	safi_t safi;
+
+	if (action == CAPABILITY_ACTION_SET) {
+		if (len % CAPABILITY_CODE_ADDPATH_LEN) {
+			flog_warn(EC_BGP_CAPABILITY_INVALID_LENGTH,
+				  "Add Path: Received invalid length %zu, non-multiple of 4",
+				  len);
+			return;
+		}
+
+		SET_FLAG(peer->cap, PEER_CAP_ADDPATH_RCV);
+
+		while (data + CAPABILITY_CODE_ADDPATH_LEN <= end) {
+			afi_t afi;
+			safi_t safi;
+			iana_afi_t pkt_afi;
+			iana_safi_t pkt_safi;
+			struct bgp_addpath_capability bac;
+
+			memcpy(&bac, data, sizeof(bac));
+			pkt_afi = ntohs(bac.afi);
+			pkt_safi = safi_int2iana(bac.safi);
+
+			if (bgp_debug_neighbor_events(peer))
+				zlog_debug("%s OPEN has %s capability for afi/safi: %s/%s%s%s",
+					   peer->host,
+					   lookup_msg(capcode_str, hdr->code,
+						      NULL),
+					   iana_afi2str(pkt_afi),
+					   iana_safi2str(pkt_safi),
+					   (bac.flags & BGP_ADDPATH_RX)
+						   ? ", receive"
+						   : "",
+					   (bac.flags & BGP_ADDPATH_TX)
+						   ? ", transmit"
+						   : "");
+
+			if (bgp_map_afi_safi_iana2int(pkt_afi, pkt_safi, &afi,
+						      &safi)) {
+				if (bgp_debug_neighbor_events(peer))
+					zlog_debug("%s Addr-family %s/%s(afi/safi) not supported. Ignore the Addpath Attribute for this AFI/SAFI",
+						   peer->host,
+						   iana_afi2str(pkt_afi),
+						   iana_safi2str(pkt_safi));
+				continue;
+			} else if (!peer->afc[afi][safi]) {
+				if (bgp_debug_neighbor_events(peer))
+					zlog_debug("%s Addr-family %s/%s(afi/safi) not enabled. Ignore the AddPath capability for this AFI/SAFI",
+						   peer->host,
+						   iana_afi2str(pkt_afi),
+						   iana_safi2str(pkt_safi));
+				continue;
+			}
+
+			if (CHECK_FLAG(bac.flags, BGP_ADDPATH_RX))
+				SET_FLAG(peer->af_cap[afi][safi],
+					 PEER_CAP_ADDPATH_AF_RX_RCV);
+			else
+				UNSET_FLAG(peer->af_cap[afi][safi],
+					   PEER_CAP_ADDPATH_AF_RX_RCV);
+
+			if (CHECK_FLAG(bac.flags, BGP_ADDPATH_TX))
+				SET_FLAG(peer->af_cap[afi][safi],
+					 PEER_CAP_ADDPATH_AF_TX_RCV);
+			else
+				UNSET_FLAG(peer->af_cap[afi][safi],
+					   PEER_CAP_ADDPATH_AF_TX_RCV);
+
+			data += CAPABILITY_CODE_ADDPATH_LEN;
+		}
+	} else {
+		FOREACH_AFI_SAFI (afi, safi) {
+			UNSET_FLAG(peer->af_cap[afi][safi],
+				   PEER_CAP_ADDPATH_AF_RX_RCV);
+			UNSET_FLAG(peer->af_cap[afi][safi],
+				   PEER_CAP_ADDPATH_AF_TX_RCV);
+		}
+
+		UNSET_FLAG(peer->cap, PEER_CAP_ADDPATH_RCV);
+	}
+}
+
 static void bgp_dynamic_capability_llgr(uint8_t *pnt, int action,
 					struct capability_header *hdr,
 					struct peer *peer)
@@ -3225,11 +3398,13 @@ static int bgp_capability_msg_parse(struct peer *peer, uint8_t *pnt,
 		case CAPABILITY_CODE_LLGR:
 			bgp_dynamic_capability_llgr(pnt, action, hdr, peer);
 			break;
+		case CAPABILITY_CODE_ADDPATH:
+			bgp_dynamic_capability_addpath(pnt, action, hdr, peer);
+			break;
 		case CAPABILITY_CODE_REFRESH:
 		case CAPABILITY_CODE_ORF:
 		case CAPABILITY_CODE_AS4:
 		case CAPABILITY_CODE_DYNAMIC:
-		case CAPABILITY_CODE_ADDPATH:
 		case CAPABILITY_CODE_ENHANCED_RR:
 		case CAPABILITY_CODE_FQDN:
 		case CAPABILITY_CODE_ENHE:

bgpd/bgp_vty.c

@@ -8840,13 +8840,21 @@ DEFUN(neighbor_disable_addpath_rx,
 	struct peer *peer;
 	afi_t afi = bgp_node_afi(vty);
 	safi_t safi = bgp_node_safi(vty);
+	int ret;
+	int action;
 
 	peer = peer_and_group_lookup_vty(vty, peer_str);
 	if (!peer)
 		return CMD_WARNING_CONFIG_FAILED;
 
-	return peer_af_flag_set_vty(vty, peer_str, afi, safi,
+	action = bgp_addpath_capability_action(peer->addpath_type[afi][safi], 0);
-				    PEER_FLAG_DISABLE_ADDPATH_RX);
+
+	ret = peer_af_flag_set_vty(vty, peer_str, afi, safi,
+				   PEER_FLAG_DISABLE_ADDPATH_RX);
+
+	bgp_capability_send(peer, afi, safi, CAPABILITY_CODE_ADDPATH, action);
+
+	return ret;
 }
 
 DEFUN(no_neighbor_disable_addpath_rx,
@@ -8861,13 +8869,21 @@ DEFUN(no_neighbor_disable_addpath_rx,
 	struct peer *peer;
 	afi_t afi = bgp_node_afi(vty);
 	safi_t safi = bgp_node_safi(vty);
+	int ret;
+	int action;
 
 	peer = peer_and_group_lookup_vty(vty, peer_str);
 	if (!peer)
 		return CMD_WARNING_CONFIG_FAILED;
 
-	return peer_af_flag_unset_vty(vty, peer_str, afi, safi,
+	action = bgp_addpath_capability_action(peer->addpath_type[afi][safi], 0);
-				      PEER_FLAG_DISABLE_ADDPATH_RX);
+
+	ret = peer_af_flag_unset_vty(vty, peer_str, afi, safi,
+				     PEER_FLAG_DISABLE_ADDPATH_RX);
+
+	bgp_capability_send(peer, afi, safi, CAPABILITY_CODE_ADDPATH, action);
+
+	return ret;
 }
 
 DEFUN (neighbor_addpath_tx_all_paths,
@@ -8879,13 +8895,15 @@ DEFUN (neighbor_addpath_tx_all_paths,
 {
 	int idx_peer = 1;
 	struct peer *peer;
+	afi_t afi = bgp_node_afi(vty);
+	safi_t safi = bgp_node_safi(vty);
 
 	peer = peer_and_group_lookup_vty(vty, argv[idx_peer]->arg);
 	if (!peer)
 		return CMD_WARNING_CONFIG_FAILED;
 
-	bgp_addpath_set_peer_type(peer, bgp_node_afi(vty), bgp_node_safi(vty),
+	bgp_addpath_set_peer_type(peer, afi, safi, BGP_ADDPATH_ALL, 0);
-				  BGP_ADDPATH_ALL, 0);
+
 	return CMD_SUCCESS;
 }
 
@@ -8905,20 +8923,20 @@ DEFUN (no_neighbor_addpath_tx_all_paths,
 {
 	int idx_peer = 2;
 	struct peer *peer;
+	afi_t afi = bgp_node_afi(vty);
+	safi_t safi = bgp_node_safi(vty);
 
 	peer = peer_and_group_lookup_vty(vty, argv[idx_peer]->arg);
 	if (!peer)
 		return CMD_WARNING_CONFIG_FAILED;
 
-	if (peer->addpath_type[bgp_node_afi(vty)][bgp_node_safi(vty)]
+	if (peer->addpath_type[afi][safi] != BGP_ADDPATH_ALL) {
-	    != BGP_ADDPATH_ALL) {
 		vty_out(vty,
 			"%% Peer not currently configured to transmit all paths.");
 		return CMD_WARNING_CONFIG_FAILED;
 	}
 
-	bgp_addpath_set_peer_type(peer, bgp_node_afi(vty), bgp_node_safi(vty),
+	bgp_addpath_set_peer_type(peer, afi, safi, BGP_ADDPATH_NONE, 0);
-				  BGP_ADDPATH_NONE, 0);
 
 	return CMD_SUCCESS;
 }

bgpd/bgpd.c

@@ -4552,7 +4552,7 @@ static const struct peer_flag_action peer_af_flag_action_list[] = {
 	{PEER_FLAG_AS_OVERRIDE, 1, peer_change_reset_out},
 	{PEER_FLAG_REMOVE_PRIVATE_AS_ALL_REPLACE, 1, peer_change_reset_out},
 	{PEER_FLAG_WEIGHT, 0, peer_change_reset_in},
-	{PEER_FLAG_DISABLE_ADDPATH_RX, 0, peer_change_reset},
+	{PEER_FLAG_DISABLE_ADDPATH_RX, 0, peer_change_none},
 	{PEER_FLAG_SOO, 0, peer_change_reset},
 	{PEER_FLAG_ACCEPT_OWN, 0, peer_change_reset},
 	{0, 0, 0}};

tests/topotests/bgp_dynamic_capability/r1/frr.conf

@@ -12,4 +12,8 @@ router bgp 65001
  neighbor 192.168.1.2 timers 1 3
  neighbor 192.168.1.2 timers connect 1
  neighbor 192.168.1.2 capability dynamic
+ !
+ address-family ipv4 unicast
+  neighbor 192.168.1.2 addpath-tx-all-paths
+ exit-address-family
 !

tests/topotests/bgp_dynamic_capability/test_bgp_dynamic_capability_addpath.py

@@ -0,0 +1,170 @@
+#!/usr/bin/env python
+# SPDX-License-Identifier: ISC
+
+# Copyright (c) 2023 by
+# Donatas Abraitis <donatas@opensourcerouting.org>
+#
+
+"""
+Test if Addpath capability is adjusted dynamically.
+"""
+
+import os
+import re
+import sys
+import json
+import pytest
+import functools
+
+pytestmark = pytest.mark.bgpd
+
+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 setup_module(mod):
+    topodef = {"s1": ("r1", "r2")}
+    tgen = Topogen(topodef, mod.__name__)
+    tgen.start_topology()
+
+    router_list = tgen.routers()
+
+    for _, (rname, router) in enumerate(router_list.items(), 1):
+        router.load_frr_config(os.path.join(CWD, "{}/frr.conf".format(rname)))
+
+    tgen.start_router()
+
+
+def teardown_module(mod):
+    tgen = get_topogen()
+    tgen.stop_topology()
+
+
+def test_bgp_dynamic_capability_role():
+    tgen = get_topogen()
+
+    if tgen.routers_have_failure():
+        pytest.skip(tgen.errors)
+
+    r1 = tgen.gears["r1"]
+    r2 = tgen.gears["r2"]
+
+    def _bgp_converge():
+        output = json.loads(r1.vtysh_cmd("show bgp neighbor json"))
+        expected = {
+            "192.168.1.2": {
+                "bgpState": "Established",
+                "neighborCapabilities": {
+                    "dynamic": "advertisedAndReceived",
+                    "addPath": {
+                        "ipv4Unicast": {
+                            "txAdvertised": True,
+                            "rxAdvertisedAndReceived": True,
+                        }
+                    },
+                },
+            }
+        }
+        return topotest.json_cmp(output, expected)
+
+    test_func = functools.partial(
+        _bgp_converge,
+    )
+    _, result = topotest.run_and_expect(test_func, None, count=30, wait=1)
+    assert result is None, "Can't converge"
+
+    step("Enable Addpath capability and check if it's exchanged dynamically")
+
+    # Clear message stats to check if we receive a notification or not after we
+    # change the settings fo LLGR.
+    r1.vtysh_cmd("clear bgp 192.168.1.2 message-stats")
+    r2.vtysh_cmd(
+        """
+    configure terminal
+    router bgp
+     address-family ipv4 unicast
+      neighbor 192.168.1.1 addpath-tx-all-paths
+    """
+    )
+
+    def _bgp_check_if_addpath_rx_tx_and_session_not_reset():
+        output = json.loads(r1.vtysh_cmd("show bgp neighbor json"))
+        expected = {
+            "192.168.1.2": {
+                "bgpState": "Established",
+                "neighborCapabilities": {
+                    "dynamic": "advertisedAndReceived",
+                    "addPath": {
+                        "ipv4Unicast": {
+                            "txAdvertisedAndReceived": True,
+                            "rxAdvertisedAndReceived": True,
+                        }
+                    },
+                },
+                "messageStats": {
+                    "notificationsRecv": 0,
+                    "capabilityRecv": 1,
+                },
+            }
+        }
+        return topotest.json_cmp(output, expected)
+
+    test_func = functools.partial(
+        _bgp_check_if_addpath_rx_tx_and_session_not_reset,
+    )
+    _, result = topotest.run_and_expect(test_func, None, count=30, wait=1)
+    assert result is None, "Session was reset after enabling Addpath capability"
+
+    step("Disable Addpath capability RX and check if it's exchanged dynamically")
+
+    # Clear message stats to check if we receive a notification or not after we
+    # change the settings fo LLGR.
+    r1.vtysh_cmd("clear bgp 192.168.1.2 message-stats")
+    r2.vtysh_cmd(
+        """
+    configure terminal
+    router bgp
+     address-family ipv4 unicast
+      neighbor 192.168.1.1 disable-addpath-rx
+    """
+    )
+
+    def _bgp_check_if_addpath_tx_and_session_not_reset():
+        output = json.loads(r1.vtysh_cmd("show bgp neighbor json"))
+        expected = {
+            "192.168.1.2": {
+                "bgpState": "Established",
+                "neighborCapabilities": {
+                    "dynamic": "advertisedAndReceived",
+                    "addPath": {
+                        "ipv4Unicast": {
+                            "txAdvertisedAndReceived": True,
+                            "rxAdvertised": True,
+                        }
+                    },
+                },
+                "messageStats": {
+                    "notificationsRecv": 0,
+                    "capabilityRecv": 1,
+                },
+            }
+        }
+        return topotest.json_cmp(output, expected)
+
+    test_func = functools.partial(
+        _bgp_check_if_addpath_tx_and_session_not_reset,
+    )
+    _, result = topotest.run_and_expect(test_func, None, count=30, wait=1)
+    assert result is None, "Session was reset after disabling Addpath RX flags"
+
+
+if __name__ == "__main__":
+    args = ["-s"] + sys.argv[1:]
+    sys.exit(pytest.main(args))