bgpd: Fix BGP-LS initial TED sync and cleanup on peer deactivation

bgpd/bgp_ls.c

@@ -729,6 +729,11 @@ bool bgp_ls_register(struct bgp *bgp)
 		return false;
 	}
 
+	if (ls_request_sync(bgp_zclient) == -1)
+		zlog_warn("BGP-LS: Failed to request initial Link State database sync");
+	else
+		zlog_info("BGP-LS: Requested initial Link State database sync");
+
 	bgp->ls_info->registered_ls_db = true;
 
 	zlog_info("BGP-LS: Registered with Link State database for BGP instance %s",

bgpd/bgp_ls_ted.c

@@ -20,6 +20,7 @@
 #include "bgpd/bgp_ls.h"
 #include "bgpd/bgp_ls_nlri.h"
 #include "bgpd/bgp_ls_ted.h"
+#include "bgpd/bgp_route.h"
 
 /*
  * ===========================================================================
@@ -957,6 +958,7 @@ int bgp_ls_process_vertex(struct bgp *bgp, struct ls_vertex *vertex, uint8_t eve
 	}
 
 	switch (event) {
+	case LS_MSG_EVENT_SYNC:
 	case LS_MSG_EVENT_ADD:
 	case LS_MSG_EVENT_UPDATE:
 		return bgp_ls_originate_node(bgp, protocol_id, router_id, router_id_len, area_id,
@@ -1030,6 +1032,7 @@ int bgp_ls_process_edge(struct bgp *bgp, struct ls_edge *edge, uint8_t event)
 	}
 
 	switch (event) {
+	case LS_MSG_EVENT_SYNC:
 	case LS_MSG_EVENT_ADD:
 	case LS_MSG_EVENT_UPDATE:
 		return bgp_ls_originate_link(bgp, protocol_id, local_router_id,
@@ -1092,6 +1095,7 @@ int bgp_ls_process_subnet(struct bgp *bgp, struct ls_subnet *subnet, uint8_t eve
 	}
 
 	switch (event) {
+	case LS_MSG_EVENT_SYNC:
 	case LS_MSG_EVENT_ADD:
 	case LS_MSG_EVENT_UPDATE:
 		return bgp_ls_originate_prefix(bgp, protocol_id, router_id, router_id_len,
@@ -1168,7 +1172,8 @@ int bgp_ls_process_message(struct bgp *bgp, struct ls_message *msg)
 		if (BGP_DEBUG(zebra, ZEBRA) || BGP_DEBUG(linkstate, LINKSTATE))
 			zlog_debug("%s: Link edge", __func__);
 
-		if (msg->event == LS_MSG_EVENT_ADD || msg->event == LS_MSG_EVENT_UPDATE) {
+		if (msg->event == LS_MSG_EVENT_SYNC || msg->event == LS_MSG_EVENT_ADD ||
+		    msg->event == LS_MSG_EVENT_UPDATE) {
 			/* Search for the reverse edge and link both directions. */
 			reverse_edge = ls_find_edge_by_destination(bgp->ls_info->ted,
 								   edge->attributes);
@@ -1212,7 +1217,8 @@ int bgp_ls_process_message(struct bgp *bgp, struct ls_message *msg)
 			 * destination.
 			 */
 			if (reverse_edge &&
-			    (msg->event == LS_MSG_EVENT_ADD || reverse_edge_dst_updated)) {
+			    (msg->event == LS_MSG_EVENT_SYNC || msg->event == LS_MSG_EVENT_ADD ||
+			     reverse_edge_dst_updated)) {
 				uint8_t reverse_event = msg->event;
 
 				if (msg->event == LS_MSG_EVENT_UPDATE && reverse_edge_dst_updated)
@@ -1264,6 +1270,49 @@ int bgp_ls_process_message(struct bgp *bgp, struct ls_message *msg)
 	return 0;
 }
 
+/*
+ * Remove all entries from the TED.
+ */
+static void bgp_ls_ted_clear(struct ls_ted *ted)
+{
+	struct ls_vertex *vertex;
+	struct ls_edge *edge;
+	struct ls_subnet *subnet;
+
+	frr_each_safe (vertices, &ted->vertices, vertex)
+		ls_vertex_del_all(ted, vertex);
+	frr_each_safe (edges, &ted->edges, edge)
+		ls_edge_del_all(ted, edge);
+	frr_each_safe (subnets, &ted->subnets, subnet)
+		ls_subnet_del_all(ted, subnet);
+}
+
+/*
+ * Withdraw all locally originated BGP-LS routes and reset the TED.
+ *
+ * Called when the last BGP-LS peer is deactivated: performs a single bulk
+ * walk of the BGP-LS RIB via bgp_clear_route() to remove all self-originated
+ * paths at once, then clears all TED entries.
+ *
+ * @param bgp - BGP instance
+ */
+void bgp_ls_withdraw_ted(struct bgp *bgp)
+{
+	if (!bgp || !bgp->ls_info || !bgp->ls_info->ted)
+		return;
+
+	if (BGP_DEBUG(linkstate, LINKSTATE))
+		zlog_debug("BGP-LS: Withdrawing all locally originated routes and resetting TED");
+
+	/* Remove all self-originated BGP-LS paths from the RIB */
+	bgp_clear_route(bgp->peer_self, AFI_BGP_LS, SAFI_BGP_LS);
+
+	/* Clear all TED entries */
+	bgp_ls_ted_clear(bgp->ls_info->ted);
+
+	zlog_info("BGP-LS: All locally originated BGP-LS routes withdrawn and TED reset");
+}
+
 /*
  * Handle link-state SYNC/UPDATE messages from zebra
  */

bgpd/bgp_ls_ted.h

@@ -208,4 +208,15 @@ extern int bgp_ls_process_linkstate_message(struct stream *s, uint8_t msg_type);
  */
 extern int bgp_ls_process_message(struct bgp *bgp, struct ls_message *msg);
 
+/*
+ * Withdraw all locally originated BGP-LS routes and reset the TED.
+ *
+ * Called when the last BGP-LS peer is deactivated. Withdraws every node,
+ * link, and prefix NLRI that was originated from the TED, then discards
+ * the stale TED.
+ *
+ * @param bgp - BGP instance
+ */
+extern void bgp_ls_withdraw_ted(struct bgp *bgp);
+
 #endif /* _FRR_BGP_LS_TED_H */

bgpd/bgpd.c

@@ -81,6 +81,7 @@
 #include "bgpd/bgp_trace.h"
 #include "bgpd/bgp_srv6.h"
 #include "bgpd/bgp_ls.h"
+#include "bgpd/bgp_ls_ted.h"
 
 DEFINE_MTYPE_STATIC(BGPD, PEER_TX_SHUTDOWN_MSG, "Peer shutdown message (TX)");
 DEFINE_QOBJ_TYPE(bgp_master);
@@ -2850,6 +2851,8 @@ int peer_deactivate(struct peer *peer, afi_t afi, safi_t safi)
 		}
 
 		if (last_peer) {
+			bgp_ls_withdraw_ted(bgp);
+
 			if (!bgp_ls_unregister(bgp)) {
 				zlog_err("BGP-LS: Failed to unregister from link-state database for instance %s",
 					 bgp->name_pretty);

tests/topotests/bgp_link_state/test_bgp_link_state.py

@@ -213,6 +213,22 @@ def get_bgp_ls_count(router):
     return len(data)
 
 
+def check_bgp_ls_empty(router):
+    """
+    Check that the BGP-LS routing table is empty.
+
+    Args:
+        router: Router instance
+
+    Returns:
+        None if table is empty, error message otherwise
+    """
+    count = get_bgp_ls_count(router)
+    if count > 0:
+        return f"BGP-LS table not empty: {count} route(s) still present"
+    return None
+
+
 def build_topo(tgen):
     """Build the test topology"""
 
@@ -853,6 +869,97 @@ def test_bgp_ls_r4_link_no_shutdown():
     assert result is None, '"rr" did not receive BGP-LS r4 link up update'
 
 
+def test_bgp_ls_peer_deactivate():
+    """
+    Test that deactivating the last BGP-LS peer:
+    - Withdraws all locally originated BGP-LS routes on the producer (r2)
+    - Clears all received BGP-LS routes on the consumer (rr)
+    """
+    tgen = get_topogen()
+
+    if tgen.routers_have_failure():
+        pytest.skip(tgen.errors)
+
+    logger.info(
+        "Deactivating BGP-LS peer on r2 and verifying route withdrawal on r2 and rr"
+    )
+
+    r2 = tgen.gears["r2"]
+
+    # Deactivate the only BGP-LS peer on r2 (neighbor 10.0.3.4 = rr).
+    r2.vtysh_cmd(
+        "configure terminal\n"
+        "router bgp 65000\n"
+        "address-family link-state\n"
+        "no neighbor 10.0.3.4 activate"
+    )
+
+    # r2 must have withdrawn all its locally originated BGP-LS routes
+    test_func = functools.partial(check_bgp_ls_empty, r2)
+    _, result = topotest.run_and_expect(test_func, None, count=30, wait=1)
+    assert result is None, '"r2" BGP-LS routes not withdrawn after peer deactivation'
+
+    # rr (consumer) must have no BGP-LS routes once r2's session goes down
+    consumer = tgen.gears["rr"]
+    test_func = functools.partial(check_bgp_ls_empty, consumer)
+    _, result = topotest.run_and_expect(test_func, None, count=30, wait=1)
+    assert result is None, '"rr" BGP-LS routes not cleared after r2 peer deactivation'
+
+
+def test_bgp_ls_peer_reactivate():
+    """
+    Test that reactivating a BGP-LS peer after deactivation:
+    - Triggers a fresh TED sync from the IGP
+    - Re-originates all IGP topology as BGP-LS NLRIs
+    - Re-advertises all routes to the consumer (rr)
+
+    The previous test (test_bgp_ls_peer_deactivate) must run first.
+    """
+    tgen = get_topogen()
+
+    if tgen.routers_have_failure():
+        pytest.skip(tgen.errors)
+
+    logger.info(
+        "Reactivating BGP-LS peer on r2 and verifying route re-advertisement on r2 and rr"
+    )
+
+    r2 = tgen.gears["r2"]
+
+    # Reactivate the BGP-LS peer.
+    r2.vtysh_cmd(
+        "configure terminal\n"
+        "router bgp 65000\n"
+        "address-family link-state\n"
+        "neighbor 10.0.3.4 activate"
+    )
+
+    # r2 must re-originate all BGP-LS NLRIs for the full ISIS topology
+    reffile = os.path.join(CWD, "r2/bgp_ls_nlri.json")
+    expected = json.loads(open(reffile).read())
+    test_func = functools.partial(
+        topotest.router_json_cmp,
+        r2,
+        "show bgp link-state link-state json",
+        expected,
+    )
+    _, result = topotest.run_and_expect(test_func, None, count=60, wait=1)
+    assert result is None, '"r2" did not re-originate BGP-LS routes after peer reactivation'
+
+    # rr (consumer) must receive all BGP-LS routes again
+    consumer = tgen.gears["rr"]
+    reffile = os.path.join(CWD, "rr/bgp_ls_nlri.json")
+    expected = json.loads(open(reffile).read())
+    test_func = functools.partial(
+        topotest.router_json_cmp,
+        consumer,
+        "show bgp link-state link-state json",
+        expected,
+    )
+    _, result = topotest.run_and_expect(test_func, None, count=60, wait=1)
+    assert result is None, '"rr" did not receive BGP-LS routes after r2 peer reactivation'
+
+
 def test_memory_leak():
     """Run the memory leak test and report results"""
     tgen = get_topogen()