sccp: Handle N-NOTICE.ind (Routing Failure of SCCP CL messages)

ITU Q.714 2.8:
"""
When an end node is informed of a routing failure, this information
is forwarded towards the SCCP user by using the N-DISCONNECT primitive
(refer to reason for release in 2.1.1.2.4/Q.711) or the N-NOTICE primitive
(refer to reason for return in 2.2.2.2.4/Q.711)
"""

We are already handling N-DISCONNECT.ind for CO messages, but
N-NOTICE.ind for CL messages was not being handled.

If CL messages are not arriving to the Lb peer, then reset the link
and mark the peer as disconnected, until a new RESET can successfully fo
through.

Related: OS#5917
Change-Id: I4bfea43a99c768162faefde06558941f697bd718

include/osmocom/smlc/cell_locations.h

@@ -23,7 +23,7 @@
 
 #include <stdint.h>
 #include <osmocom/core/linuxlist.h>
-#include <osmocom/sigtran/sccp_sap.h>
+#include <osmocom/gsm/gsm0808_utils.h>
 
 struct osmo_gad;
 

include/osmocom/smlc/lb_peer.h

@@ -1,5 +1,7 @@
 #pragma once
 
+#include <stdint.h>
+
 #include <osmocom/core/linuxlist.h>
 #include <osmocom/gsm/gsm0808.h>
 #include <osmocom/sigtran/sccp_sap.h>
@@ -49,8 +51,8 @@ enum lb_peer_event {
 	LB_PEER_EV_MSG_DOWN_CO,
 	LB_PEER_EV_RX_RESET,
 	LB_PEER_EV_RX_RESET_ACK,
-	LB_PEER_EV_CONNECTION_SUCCESS,
+	LB_PEER_EV_AVAILABLE,
-	LB_PEER_EV_CONNECTION_TIMEOUT,
+	LB_PEER_EV_UNAVAILABLE,
 };
 
 struct lb_peer_ev_ctx {
@@ -60,8 +62,8 @@ struct lb_peer_ev_ctx {
 };
 
 struct lb_peer *lb_peer_find_or_create(struct sccp_lb_inst *sli, const struct osmo_sccp_addr *peer_addr);
-struct lb_peer *lb_peer_find(struct sccp_lb_inst *sli, const struct osmo_sccp_addr *peer_addr);
+struct lb_peer *lb_peer_find(const struct sccp_lb_inst *sli, const struct osmo_sccp_addr *peer_addr);
+struct lb_peer *lb_peer_find_by_pc(const struct sccp_lb_inst *sli, uint32_t pc);
 
 int lb_peer_up_l2(struct sccp_lb_inst *sli, const struct osmo_sccp_addr *calling_addr, bool co, uint32_t conn_id,
 		  struct msgb *l2);
-void lb_peer_disconnect(struct sccp_lb_inst *sli, uint32_t conn_id);

include/osmocom/smlc/smlc_data.h

@@ -37,6 +37,7 @@ enum smlc_ctrl_node {
 	_LAST_CTRL_NODE_SMLC
 };
 
+/* rate_ctr */
 enum {
 	SMLC_CTR_BSSMAP_LE_RX_UDT_RESET,
 	SMLC_CTR_BSSMAP_LE_RX_UDT_RESET_ACK,
@@ -58,3 +59,9 @@ enum {
 	SMLC_CTR_BSSMAP_LE_TX_DT1_PERFORM_LOCATION_RESPONSE,
 	SMLC_CTR_BSSMAP_LE_TX_DT1_BSSLAP_TA_REQUEST,
 };
+
+/* osmo_stat */
+enum {
+	SMLC_STAT_LB_PEERS_TOTAL,
+	SMLC_STAT_LB_PEERS_ACTIVE,
+};

include/osmocom/smlc/smlc_vty.h

@@ -5,3 +5,5 @@
 enum smlc_vty_node {
 	CELLS_NODE = _LAST_OSMOVTY_NODE + 1,
 };
+
+void smlc_vty_init(struct vty_app_info *vty_app_info);

src/osmo-smlc/Makefile.am

@@ -32,6 +32,7 @@ osmo_smlc_SOURCES = \
 	smlc_loc_req.c \
 	smlc_main.c \
 	smlc_subscr.c \
+	smlc_vty.c \
 	$(NULL)
 
 osmo_smlc_LDADD = \

src/osmo-smlc/lb_peer.c

@@ -1,5 +1,5 @@
 /*
- * (C) 2019 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
+ * (C) 2019-2025 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
  * All Rights Reserved
  *
  * SPDX-License-Identifier: AGPL-3.0+
@@ -23,6 +23,7 @@
 #include <osmocom/core/linuxlist.h>
 #include <osmocom/core/logging.h>
 #include <osmocom/core/fsm.h>
+#include <osmocom/core/stat_item.h>
 #include <osmocom/gsm/bssmap_le.h>
 #include <osmocom/sigtran/sccp_helpers.h>
 
@@ -57,6 +58,7 @@ static struct lb_peer *lb_peer_alloc(struct sccp_lb_inst *sli, const struct osmo
 	fi->priv = lbp;
 
 	llist_add(&lbp->entry, &sli->lb_peers);
+	osmo_stat_item_inc(osmo_stat_item_group_get_item(g_smlc->statg, SMLC_STAT_LB_PEERS_TOTAL), 1);
 
 	return lbp;
 }
@@ -69,7 +71,7 @@ struct lb_peer *lb_peer_find_or_create(struct sccp_lb_inst *sli, const struct os
 	return lb_peer_alloc(sli, peer_addr);
 }
 
-struct lb_peer *lb_peer_find(struct sccp_lb_inst *sli, const struct osmo_sccp_addr *peer_addr)
+struct lb_peer *lb_peer_find(const struct sccp_lb_inst *sli, const struct osmo_sccp_addr *peer_addr)
 {
 	struct lb_peer *lbp;
 	llist_for_each_entry(lbp, &sli->lb_peers, entry) {
@@ -80,6 +82,15 @@ struct lb_peer *lb_peer_find(struct sccp_lb_inst *sli, const struct osmo_sccp_ad
 	return NULL;
 }
 
+/* Find an lb_peer by its remote SCCP address */
+struct lb_peer *lb_peer_find_by_pc(const struct sccp_lb_inst *sli, uint32_t pc)
+{
+	struct osmo_sccp_addr rem_addr;
+
+	osmo_sccp_make_addr_pc_ssn(&rem_addr, pc, OSMO_SCCP_SSN_BSC_BSSAP_LE);
+	return lb_peer_find(sli, &rem_addr);
+}
+
 static const struct osmo_tdef_state_timeout lb_peer_fsm_timeouts[32] = {
 	[LB_PEER_ST_WAIT_RX_RESET_ACK] = { .T = -13 },
 	[LB_PEER_ST_DISCARDING] = { .T = -14 },
@@ -88,7 +99,7 @@ static const struct osmo_tdef_state_timeout lb_peer_fsm_timeouts[32] = {
 #define lb_peer_state_chg(LB_PEER, NEXT_STATE) \
 	osmo_tdef_fsm_inst_state_chg((LB_PEER)->fi, NEXT_STATE, lb_peer_fsm_timeouts, g_smlc_tdefs, 5)
 
-void lb_peer_discard_all_conns(struct lb_peer *lbp)
+static void lb_peer_discard_all_conns(struct lb_peer *lbp)
 {
 	struct lb_conn *lb_conn, *next;
 
@@ -137,7 +148,7 @@ static void lb_peer_rx_reset_ack(struct lb_peer *lbp, struct msgb* msg)
 	lb_peer_state_chg(lbp, LB_PEER_ST_READY);
 }
 
-void lb_peer_reset(struct lb_peer *lbp)
+static void lb_peer_reset(struct lb_peer *lbp)
 {
 	struct bssap_le_pdu reset = {
 		.discr = BSSAP_LE_MSG_DISCR_BSSMAP_LE,
@@ -167,7 +178,18 @@ void lb_peer_reset(struct lb_peer *lbp)
 	}
 }
 
-void lb_peer_allstate_action(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+static void lb_peer_disconnect(struct sccp_lb_inst *sli, uint32_t conn_id)
+{
+	struct lb_conn *lb_conn;
+	llist_for_each_entry(lb_conn, &sli->lb_conns, entry) {
+		if (lb_conn->sccp_conn_id == conn_id) {
+			lb_conn_discard(lb_conn);
+			return;
+		}
+	}
+}
+
+static void lb_peer_allstate_action(struct osmo_fsm_inst *fi, uint32_t event, void *data)
 {
 	struct lb_peer *lbp = fi->priv;
 	struct lb_peer_ev_ctx *ctx = data;
@@ -196,7 +218,7 @@ void lb_peer_allstate_action(struct osmo_fsm_inst *fi, uint32_t event, void *dat
 	}
 }
 
-void lb_peer_st_wait_rx_reset(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+static void lb_peer_st_wait_rx_reset(struct osmo_fsm_inst *fi, uint32_t event, void *data)
 {
 	struct lb_peer *lbp = fi->priv;
 	struct lb_peer_ev_ctx *ctx;
@@ -224,13 +246,22 @@ void lb_peer_st_wait_rx_reset(struct osmo_fsm_inst *fi, uint32_t event, void *da
 		lb_peer_rx_reset(lbp, msg);
 		return;
 
+	case LB_PEER_EV_AVAILABLE:
+		/* Send a RESET to the peer. */
+		lb_peer_reset(lbp);
+		return;
+
+	case LB_PEER_EV_UNAVAILABLE:
+		/* Do nothing, wait for peer to come up again. */
+		return;
+
 	default:
 		LOG_LB_PEER(lbp, LOGL_ERROR, "Unhandled event: %s\n", osmo_fsm_event_name(&lb_peer_fsm, event));
 		return;
 	}
 }
 
-void lb_peer_st_wait_rx_reset_ack(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+static void lb_peer_st_wait_rx_reset_ack(struct osmo_fsm_inst *fi, uint32_t event, void *data)
 {
 	struct lb_peer *lbp = fi->priv;
 	struct lb_peer_ev_ctx *ctx;
@@ -259,13 +290,28 @@ void lb_peer_st_wait_rx_reset_ack(struct osmo_fsm_inst *fi, uint32_t event, void
 		lb_peer_rx_reset(lbp, msg);
 		return;
 
+	case LB_PEER_EV_AVAILABLE:
+		/* Send a RESET to the peer. */
+		lb_peer_reset(lbp);
+		return;
+
+	case LB_PEER_EV_UNAVAILABLE:
+		lb_peer_state_chg(lbp, LB_PEER_ST_WAIT_RX_RESET);
+		return;
+
 	default:
 		LOG_LB_PEER(lbp, LOGL_ERROR, "Unhandled event: %s\n", osmo_fsm_event_name(&lb_peer_fsm, event));
 		return;
 	}
 }
 
-void lb_peer_st_ready(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+static void lb_peer_st_ready_onenter(struct osmo_fsm_inst *fi, uint32_t prev_state)
+{
+	if (prev_state != LB_PEER_ST_READY)
+		osmo_stat_item_inc(osmo_stat_item_group_get_item(g_smlc->statg, SMLC_STAT_LB_PEERS_ACTIVE), 1);
+}
+
+static void lb_peer_st_ready(struct osmo_fsm_inst *fi, uint32_t event, void *data)
 {
 	struct lb_peer *lbp = fi->priv;
 	struct lb_peer_ev_ctx *ctx;
@@ -323,12 +369,28 @@ void lb_peer_st_ready(struct osmo_fsm_inst *fi, uint32_t event, void *data)
 		lb_peer_rx_reset(lbp, msg);
 		return;
 
+	case LB_PEER_EV_AVAILABLE:
+		/* Send a RESET to the peer. */
+		lb_peer_reset(lbp);
+		return;
+
+	case LB_PEER_EV_UNAVAILABLE:
+		lb_peer_discard_all_conns(lbp);
+		lb_peer_state_chg(lbp, LB_PEER_ST_WAIT_RX_RESET);
+		return;
+
 	default:
 		LOG_LB_PEER(lbp, LOGL_ERROR, "Unhandled event: %s\n", osmo_fsm_event_name(&lb_peer_fsm, event));
 		return;
 	}
 }
 
+static void lb_peer_st_ready_onleave(struct osmo_fsm_inst *fi, uint32_t next_state)
+{
+	if (next_state != LB_PEER_ST_READY)
+		osmo_stat_item_dec(osmo_stat_item_group_get_item(g_smlc->statg, SMLC_STAT_LB_PEERS_ACTIVE), 1);
+}
+
 static int lb_peer_fsm_timer_cb(struct osmo_fsm_inst *fi)
 {
 	struct lb_peer *lbp = fi->priv;
@@ -336,10 +398,17 @@ static int lb_peer_fsm_timer_cb(struct osmo_fsm_inst *fi)
 	return 0;
 }
 
-void lb_peer_fsm_cleanup(struct osmo_fsm_inst *fi, enum osmo_fsm_term_cause cause)
+/* struct lb_peer destructor: */
+static void lb_peer_fsm_cleanup(struct osmo_fsm_inst *fi, enum osmo_fsm_term_cause cause)
 {
 	struct lb_peer *lbp = fi->priv;
+
 	lb_peer_discard_all_conns(lbp);
+
+	if (lbp->fi->state == LB_PEER_ST_READY)
+		osmo_stat_item_dec(osmo_stat_item_group_get_item(g_smlc->statg, SMLC_STAT_LB_PEERS_ACTIVE), 1);
+	osmo_stat_item_dec(osmo_stat_item_group_get_item(g_smlc->statg, SMLC_STAT_LB_PEERS_TOTAL), 1);
+
 	llist_del(&lbp->entry);
 }
 
@@ -352,8 +421,8 @@ static const struct value_string lb_peer_fsm_event_names[] = {
 	OSMO_VALUE_STRING(LB_PEER_EV_MSG_DOWN_CO),
 	OSMO_VALUE_STRING(LB_PEER_EV_RX_RESET),
 	OSMO_VALUE_STRING(LB_PEER_EV_RX_RESET_ACK),
-	OSMO_VALUE_STRING(LB_PEER_EV_CONNECTION_SUCCESS),
+	OSMO_VALUE_STRING(LB_PEER_EV_AVAILABLE),
-	OSMO_VALUE_STRING(LB_PEER_EV_CONNECTION_TIMEOUT),
+	OSMO_VALUE_STRING(LB_PEER_EV_UNAVAILABLE),
 	{}
 };
 
@@ -367,7 +436,8 @@ static const struct osmo_fsm_state lb_peer_fsm_states[] = {
 			| S(LB_PEER_EV_RX_RESET)
 			| S(LB_PEER_EV_MSG_UP_CO_INITIAL)
 			| S(LB_PEER_EV_MSG_UP_CO)
-			| S(LB_PEER_EV_CONNECTION_TIMEOUT)
+			| S(LB_PEER_EV_AVAILABLE)
+			| S(LB_PEER_EV_UNAVAILABLE)
 			,
 		.out_state_mask = 0
 			| S(LB_PEER_ST_WAIT_RX_RESET)
@@ -384,7 +454,8 @@ static const struct osmo_fsm_state lb_peer_fsm_states[] = {
 			| S(LB_PEER_EV_RX_RESET_ACK)
 			| S(LB_PEER_EV_MSG_UP_CO_INITIAL)
 			| S(LB_PEER_EV_MSG_UP_CO)
-			| S(LB_PEER_EV_CONNECTION_TIMEOUT)
+			| S(LB_PEER_EV_AVAILABLE)
+			| S(LB_PEER_EV_UNAVAILABLE)
 			,
 		.out_state_mask = 0
 			| S(LB_PEER_ST_WAIT_RX_RESET)
@@ -396,6 +467,8 @@ static const struct osmo_fsm_state lb_peer_fsm_states[] = {
 	[LB_PEER_ST_READY] = {
 		.name = "READY",
 		.action = lb_peer_st_ready,
+		.onenter = lb_peer_st_ready_onenter,
+		.onleave = lb_peer_st_ready_onleave,
 		.in_event_mask = 0
 			| S(LB_PEER_EV_RX_RESET)
 			| S(LB_PEER_EV_MSG_UP_CO_INITIAL)
@@ -403,6 +476,8 @@ static const struct osmo_fsm_state lb_peer_fsm_states[] = {
 			| S(LB_PEER_EV_MSG_DOWN_CO_INITIAL)
 			| S(LB_PEER_EV_MSG_DOWN_CO)
 			| S(LB_PEER_EV_MSG_DOWN_CL)
+			| S(LB_PEER_EV_AVAILABLE)
+			| S(LB_PEER_EV_UNAVAILABLE)
 			,
 		.out_state_mask = 0
 			| S(LB_PEER_ST_WAIT_RX_RESET)
@@ -482,14 +557,3 @@ int lb_peer_up_l2(struct sccp_lb_inst *sli, const struct osmo_sccp_addr *calling
 
 	return osmo_fsm_inst_dispatch(lb_peer->fi, event, &ctx);
 }
-
-void lb_peer_disconnect(struct sccp_lb_inst *sli, uint32_t conn_id)
-{
-	struct lb_conn *lb_conn;
-	llist_for_each_entry(lb_conn, &sli->lb_conns, entry) {
-		if (lb_conn->sccp_conn_id == conn_id) {
-			lb_conn_discard(lb_conn);
-			return;
-		}
-	}
-}

src/osmo-smlc/sccp_lb_inst.c

@@ -1,5 +1,5 @@
 /*
- * (C) 2020 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
+ * (C) 2020-2025 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
  * All Rights Reserved
  *
  * SPDX-License-Identifier: AGPL-3.0+
@@ -85,6 +85,126 @@ struct sccp_lb_inst *sccp_lb_init(void *talloc_ctx, struct osmo_sccp_instance *s
 	return sli;
 }
 
+static void handle_notice_ind(struct sccp_lb_inst *sli, const struct osmo_scu_notice_param *ni)
+{
+	struct lb_peer *lbp;
+
+	lbp = lb_peer_find(sli, &ni->calling_addr);
+	if (!lbp) {
+		LOG_SCCP_LB(sli, LOGL_DEBUG, "(calling_addr=%s) N-NOTICE.ind cause=%u='%s' importance=%u didn't match any lb_peer, ignoring\n",
+			    osmo_sccp_addr_dump(&ni->calling_addr),
+			    ni->cause, osmo_sccp_return_cause_name(ni->cause),
+			    ni->importance);
+		return;
+	}
+
+	LOG_LB_PEER(lbp, LOGL_NOTICE, "N-NOTICE.ind cause=%u='%s' importance=%u\n",
+		     ni->cause, osmo_sccp_return_cause_name(ni->cause),
+		     ni->importance);
+
+	switch (ni->cause) {
+	case SCCP_RETURN_CAUSE_SUBSYSTEM_CONGESTION:
+	case SCCP_RETURN_CAUSE_NETWORK_CONGESTION:
+		/* Transient failures (hopefully), keep going. */
+		return;
+	default:
+		break;
+	}
+
+	/* Messages are not arriving to lb_peer. Signal it is unavailable to update local state. */
+	osmo_fsm_inst_dispatch(lbp->fi, LB_PEER_EV_UNAVAILABLE, NULL);
+}
+
+static void handle_pcstate_ind(struct sccp_lb_inst *sli, const struct osmo_scu_pcstate_param *pcst)
+{
+	struct osmo_ss7_instance *cs7 = osmo_sccp_get_ss7(sli->sccp);
+	struct lb_peer *lbp;
+	bool connected;
+	bool disconnected;
+
+	LOG_SCCP_LB(sli, LOGL_DEBUG, "N-PCSTATE ind: affected_pc=%u=%s sp_status=%s remote_sccp_status=%s\n",
+		    pcst->affected_pc, osmo_ss7_pointcode_print(cs7, pcst->affected_pc),
+		    osmo_sccp_sp_status_name(pcst->sp_status),
+		    osmo_sccp_rem_sccp_status_name(pcst->remote_sccp_status));
+
+	/* If we don't care about that point-code, ignore PCSTATE. */
+	lbp = lb_peer_find_by_pc(sli, pcst->affected_pc);
+	if (!lbp) {
+		LOG_SCCP_LB(sli, LOGL_DEBUG, "No lb_peer found under pc=%u=%s\n",
+			    pcst->affected_pc, osmo_ss7_pointcode_print(cs7, pcst->affected_pc));
+		return;
+	}
+
+	/* See if this marks the point code to have become available, or to have been lost.
+	 *
+	 * I want to detect two events:
+	 * - connection event (both indicators say PC is reachable).
+	 * - disconnection event (at least one indicator says the PC is not reachable).
+	 *
+	 * There are two separate incoming indicators with various possible values -- the incoming events can be:
+	 *
+	 * - neither connection nor disconnection indicated -- just indicating congestion
+	 *   connected == false, disconnected == false --> do nothing.
+	 * - both incoming values indicate that we are connected
+	 *   --> trigger connected
+	 * - both indicate we are disconnected
+	 *   --> trigger disconnected
+	 * - one value indicates 'connected', the other indicates 'disconnected'
+	 *   --> trigger disconnected
+	 *
+	 * Congestion could imply that we're connected, but it does not indicate that a PC's reachability changed, so no need to
+	 * trigger on that.
+	 */
+	connected = false;
+	disconnected = false;
+
+	switch (pcst->sp_status) {
+	case OSMO_SCCP_SP_S_ACCESSIBLE:
+		connected = true;
+		break;
+	case OSMO_SCCP_SP_S_INACCESSIBLE:
+		disconnected = true;
+		break;
+	default:
+	case OSMO_SCCP_SP_S_CONGESTED:
+		/* Neither connecting nor disconnecting */
+		break;
+	}
+
+	switch (pcst->remote_sccp_status) {
+	case OSMO_SCCP_REM_SCCP_S_AVAILABLE:
+		if (!disconnected)
+			connected = true;
+		break;
+	case OSMO_SCCP_REM_SCCP_S_UNAVAILABLE_UNKNOWN:
+	case OSMO_SCCP_REM_SCCP_S_UNEQUIPPED:
+	case OSMO_SCCP_REM_SCCP_S_INACCESSIBLE:
+		disconnected = true;
+		connected = false;
+		break;
+	default:
+	case OSMO_SCCP_REM_SCCP_S_CONGESTED:
+		/* Neither connecting nor disconnecting */
+		break;
+	}
+
+	if (disconnected) {
+		LOG_SCCP_LB(sli, LOGL_NOTICE,
+			    "now unreachable: N-PCSTATE ind: pc=%u=%s sp_status=%s remote_sccp_status=%s\n",
+			    pcst->affected_pc, osmo_ss7_pointcode_print(cs7, pcst->affected_pc),
+			    osmo_sccp_sp_status_name(pcst->sp_status),
+			    osmo_sccp_rem_sccp_status_name(pcst->remote_sccp_status));
+		osmo_fsm_inst_dispatch(lbp->fi, LB_PEER_EV_UNAVAILABLE, NULL);
+	} else if (connected) {
+		LOG_SCCP_LB(sli, LOGL_NOTICE,
+			    "now available: N-PCSTATE ind: pc=%u=%s sp_status=%s remote_sccp_status=%s\n",
+			    pcst->affected_pc, osmo_ss7_pointcode_print(cs7, pcst->affected_pc),
+			    osmo_sccp_sp_status_name(pcst->sp_status),
+			    osmo_sccp_rem_sccp_status_name(pcst->remote_sccp_status));
+		osmo_fsm_inst_dispatch(lbp->fi, LB_PEER_EV_AVAILABLE, NULL);
+	}
+}
+
 static int sccp_lb_sap_up(struct osmo_prim_hdr *oph, void *_scu)
 {
 	struct osmo_sccp_user *scu = _scu;
@@ -163,6 +283,24 @@ static int sccp_lb_sap_up(struct osmo_prim_hdr *oph, void *_scu)
 		rc = lb_peer_up_l2(sli, peer_addr, false, 0, oph->msg);
 		break;
 
+	case OSMO_PRIM(OSMO_SCU_PRIM_N_NOTICE, PRIM_OP_INDICATION):
+		handle_notice_ind(sli, &prim->u.notice);
+		rc = 0;
+		break;
+
+	case OSMO_PRIM(OSMO_SCU_PRIM_N_PCSTATE, PRIM_OP_INDICATION):
+		handle_pcstate_ind(sli, &prim->u.pcstate);
+		rc = 0;
+		break;
+
+	case OSMO_PRIM(OSMO_SCU_PRIM_N_STATE, PRIM_OP_INDICATION):
+		LOG_SCCP_LB(sli, LOGL_INFO,
+			    "SCCP-User-SAP: Ignoring %s.%s\n",
+			    osmo_scu_prim_type_name(oph->primitive),
+			    get_value_string(osmo_prim_op_names, oph->operation));
+		rc = 0;
+		break;
+
 	default:
 		LOG_SCCP_LB_CL(sli, NULL, LOGL_ERROR, "%s(%s) unsupported\n", __func__, osmo_scu_prim_name(oph));
 		rc = -1;

src/osmo-smlc/smlc_data.c

@@ -54,6 +54,19 @@ static const struct rate_ctr_group_desc smlc_ctrg_desc = {
 	smlc_ctr_description,
 };
 
+static const struct osmo_stat_item_desc smlc_stat_item_description[] = {
+	[SMLC_STAT_LB_PEERS_TOTAL]	= { "lb_peers.total", "Total Lb peers seen since startup", OSMO_STAT_ITEM_NO_UNIT, 4, 0},
+	[SMLC_STAT_LB_PEERS_ACTIVE]	= { "lb_peers.active", "Currently active Lb peers", OSMO_STAT_ITEM_NO_UNIT, 4, 0},
+};
+
+static const struct osmo_stat_item_group_desc smlc_statg_desc = {
+	"smlc",
+	"serving mobile location center",
+	OSMO_STATS_CLASS_GLOBAL,
+	ARRAY_SIZE(smlc_stat_item_description),
+	smlc_stat_item_description,
+};
+
 struct smlc_state *smlc_state_alloc(void *ctx)
 {
 	struct smlc_state *smlc = talloc_zero(ctx, struct smlc_state);
@@ -61,5 +74,14 @@ struct smlc_state *smlc_state_alloc(void *ctx)
 	INIT_LLIST_HEAD(&smlc->subscribers);
 	INIT_LLIST_HEAD(&smlc->cell_locations);
 	smlc->ctrs = rate_ctr_group_alloc(smlc, &smlc_ctrg_desc, 0);
+
+	smlc->statg = osmo_stat_item_group_alloc(smlc, &smlc_statg_desc, 0);
+	if (!smlc->statg)
+		goto ret_free;
 	return smlc;
+
+ret_free:
+	rate_ctr_group_free(smlc->ctrs);
+	talloc_free(smlc);
+	return NULL;
 }

src/osmo-smlc/smlc_main.c

@@ -19,7 +19,6 @@
 #include <osmocom/ctrl/control_cmd.h>
 #include <osmocom/ctrl/control_if.h>
 #include <osmocom/ctrl/ports.h>
-#include <osmocom/ctrl/control_vty.h>
 
 #include <osmocom/core/application.h>
 #include <osmocom/core/linuxlist.h>
@@ -29,9 +28,6 @@
 #include <osmocom/core/rate_ctr.h>
 #include <osmocom/vty/telnet_interface.h>
 #include <osmocom/vty/ports.h>
-#include <osmocom/vty/logging.h>
-#include <osmocom/vty/command.h>
-#include <osmocom/vty/misc.h>
 
 #include <osmocom/sigtran/xua_msg.h>
 #include <osmocom/sigtran/sccp_sap.h>
@@ -40,7 +36,7 @@
 #include <osmocom/smlc/debug.h>
 #include <osmocom/smlc/smlc_data.h>
 #include <osmocom/smlc/sccp_lb_inst.h>
-#include <osmocom/smlc/cell_locations.h>
+#include <osmocom/smlc/smlc_vty.h>
 
 #define _GNU_SOURCE
 #include <getopt.h>
@@ -241,17 +237,11 @@ int main(int argc, char **argv)
 
 	g_smlc = smlc_state_alloc(tall_smlc_ctx);
 
-	/* This needs to precede handle_options() */
-	vty_init(&vty_info);
-	logging_vty_add_cmds();
-	osmo_talloc_vty_add_cmds();
-	ctrl_vty_init(tall_smlc_ctx);
-	cell_locations_vty_init();
-
 	/* Initialize SS7 */
 	OSMO_ASSERT(osmo_ss7_init() == 0);
-	osmo_ss7_vty_init_asp(tall_smlc_ctx);
+
-	osmo_sccp_vty_init();
+	/* This needs to precede handle_options() */
+	smlc_vty_init(&vty_info);
 
 	/* parse options */
 	handle_options(argc, argv);

src/osmo-smlc/smlc_vty.c

@@ -0,0 +1,48 @@
+/*
+ * (C) 2025 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
+ * All Rights Reserved
+ *
+ * SPDX-License-Identifier: AGPL-3.0+
+ *
+ * Author: Pau Espin Pedrol
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <osmocom/ctrl/control_vty.h>
+#include <osmocom/vty/logging.h>
+#include <osmocom/vty/misc.h>
+#include <osmocom/vty/stats.h>
+#include <osmocom/vty/vty.h>
+
+#include <osmocom/sigtran/osmo_ss7.h>
+#include <osmocom/sigtran/sccp_sap.h>
+
+#include <osmocom/smlc/cell_locations.h>
+
+void smlc_vty_init(struct vty_app_info *vty_app_info)
+{
+	vty_init(vty_app_info);
+
+	logging_vty_add_cmds();
+	osmo_talloc_vty_add_cmds();
+	ctrl_vty_init(vty_app_info->tall_ctx);
+	osmo_fsm_vty_add_cmds();
+	osmo_stats_vty_add_cmds();
+
+	osmo_ss7_vty_init_asp(vty_app_info->tall_ctx);
+	osmo_sccp_vty_init();
+
+	cell_locations_vty_init();
+}