isisd: implement TI-LFA protection for Adj-SIDs

Signed-off-by: Renato Westphal <renato@opensourcerouting.org>

isisd/isis_lfa.c

@@ -678,8 +678,24 @@ int isis_lfa_check(struct isis_spftree *spftree_pc, struct isis_vertex *vertex)
 	}
 
 	/*
-	 * Check if the adjacency was already covered by node protection.
+	 * Check if the route/adjacency was already covered by node protection.
 	 */
+	if (VTYPE_IS(vertex->type)) {
+		struct isis_adjacency *adj;
+
+		adj = isis_adj_find(spftree_pc->area, spftree_pc->level,
+				    vertex->N.id);
+		if (adj
+		    && isis_sr_adj_sid_find(adj, spftree_pc->family,
+					    ISIS_SR_LAN_BACKUP)) {
+			if (IS_DEBUG_TILFA)
+				zlog_debug(
+					"ISIS-TI-LFA: %s %s already covered by node protection",
+					vtype2string(vertex->type), buf);
+
+			return -1;
+		}
+	}
 	if (VTYPE_IP(vertex->type)) {
 		struct route_table *route_table;
 

isisd/isis_spf.c

@@ -1236,6 +1236,29 @@ static void add_to_paths(struct isis_spftree *spftree,
 		   vertex->d_N);
 #endif /* EXTREME_DEBUG */
 
+	if (VTYPE_IS(vertex->type)
+	    && !CHECK_FLAG(spftree->flags, F_SPFTREE_NO_ADJACENCIES)) {
+		if (listcount(vertex->Adj_N) > 0) {
+			if (spftree->type == SPF_TYPE_TI_LFA) {
+				struct isis_adjacency *adj;
+
+				if (isis_lfa_check(spftree, vertex) != 0)
+					return;
+
+				adj = isis_adj_find(area, spftree->level,
+						    vertex->N.id);
+				if (adj)
+					sr_adj_sid_add_single(
+						adj, spftree->family, true,
+						vertex->Adj_N);
+			}
+		} else if (IS_DEBUG_SPF_EVENTS)
+			zlog_debug(
+				"ISIS-Spf: no adjacencies, do not install backup Adj-SID for %s depth %d dist %d",
+				vid2string(vertex, buff, sizeof(buff)),
+				vertex->depth, vertex->d_N);
+	}
+
 	if (VTYPE_IP(vertex->type)
 	    && !CHECK_FLAG(spftree->flags, F_SPFTREE_NO_ROUTES)) {
 		if (listcount(vertex->Adj_N) > 0) {
@@ -1466,6 +1489,7 @@ static int isis_run_spf_cb(struct thread *thread)
 		return ISIS_WARNING;
 	}
 
+	isis_area_delete_backup_adj_sids(area, level);
 	isis_area_invalidate_routes(area, level);
 
 	if (IS_DEBUG_SPF_EVENTS)

isisd/isis_sr.c

@@ -56,6 +56,7 @@ static void sr_local_block_delete(struct isis_area *area);
 static int sr_local_block_init(struct isis_area *area);
 static void sr_adj_sid_update(struct sr_adjacency *sra,
 			      struct sr_local_block *srlb);
+static void sr_adj_sid_del(struct sr_adjacency *sra);
 
 /* --- RB-Tree Management functions ----------------------------------------- */
 
@@ -1254,6 +1255,23 @@ static void process_node_changes(struct isis_area *area, int level,
 		process_prefix_changes(srn, srp);
 }
 
+/**
+ * Delete all backup Adj-SIDs.
+ *
+ * @param area	IS-IS area
+ * @param level	IS-IS level
+ */
+void isis_area_delete_backup_adj_sids(struct isis_area *area, int level)
+{
+	struct sr_adjacency *sra;
+	struct listnode *node, *nnode;
+
+	for (ALL_LIST_ELEMENTS(area->srdb.adj_sids, node, nnode, sra))
+		if (sra->type == ISIS_SR_LAN_BACKUP
+		    && (sra->adj->level & level))
+			sr_adj_sid_del(sra);
+}
+
 /**
  * Parse and process all SR-related Sub-TLVs after running the SPF algorithm.
  *
@@ -1499,12 +1517,13 @@ static int sr_local_block_release_label(struct sr_local_block *srlb,
 /**
  * Add new local Adjacency-SID.
  *
- * @param adj	  IS-IS Adjacency
+ * @param adj	   IS-IS Adjacency
- * @param family  Inet Family (IPv4 or IPv6)
+ * @param family   Inet Family (IPv4 or IPv6)
- * @param backup  True to initialize backup Adjacency SID
+ * @param backup   True to initialize backup Adjacency SID
+ * @param nexthops List of backup nexthops (for backup Adj-SIDs only)
  */
-static void sr_adj_sid_add_single(struct isis_adjacency *adj, int family,
+void sr_adj_sid_add_single(struct isis_adjacency *adj, int family, bool backup,
-				  bool backup)
+			   struct list *nexthops)
 {
 	struct isis_circuit *circuit = adj->circuit;
 	struct isis_area *area = circuit->area;
@@ -1555,9 +1574,25 @@ static void sr_adj_sid_add_single(struct isis_adjacency *adj, int family,
 
 	sra = XCALLOC(MTYPE_ISIS_SR_INFO, sizeof(*sra));
 	sra->type = backup ? ISIS_SR_LAN_BACKUP : ISIS_SR_ADJ_NORMAL;
+	sra->input_label = input_label;
 	sra->nexthop.family = family;
 	sra->nexthop.address = nexthop;
-	sra->nexthop.label = input_label;
+
+	if (backup && nexthops) {
+		struct isis_vertex_adj *vadj;
+		struct listnode *node;
+
+		sra->backup_nexthops = list_new();
+		for (ALL_LIST_ELEMENTS_RO(nexthops, node, vadj)) {
+			struct isis_adjacency *adj = vadj->sadj->adj;
+			struct mpls_label_stack *label_stack;
+
+			label_stack = vadj->label_stack;
+			adjinfo2nexthop(family, sra->backup_nexthops, adj,
+					label_stack);
+		}
+	}
+
 	switch (circuit->circ_type) {
 	/* LAN Adjacency-SID for Broadcast interface section #2.2.2 */
 	case CIRCUIT_T_BROADCAST:
@@ -1603,8 +1638,7 @@ static void sr_adj_sid_add_single(struct isis_adjacency *adj, int family,
  */
 static void sr_adj_sid_add(struct isis_adjacency *adj, int family)
 {
-	sr_adj_sid_add_single(adj, family, false);
+	sr_adj_sid_add_single(adj, family, false, NULL);
-	sr_adj_sid_add_single(adj, family, true);
 }
 
 static void sr_adj_sid_update(struct sr_adjacency *sra,
@@ -1616,16 +1650,16 @@ static void sr_adj_sid_update(struct sr_adjacency *sra,
 	isis_zebra_send_adjacency_sid(ZEBRA_MPLS_LABELS_DELETE, sra);
 
 	/* Got new label in the new SRLB */
-	sra->nexthop.label = sr_local_block_request_label(srlb);
+	sra->input_label = sr_local_block_request_label(srlb);
-	if (sra->nexthop.label == MPLS_INVALID_LABEL)
+	if (sra->input_label == MPLS_INVALID_LABEL)
 		return;
 
 	switch (circuit->circ_type) {
 	case CIRCUIT_T_BROADCAST:
-		sra->u.ladj_sid->sid = sra->nexthop.label;
+		sra->u.ladj_sid->sid = sra->input_label;
 		break;
 	case CIRCUIT_T_P2P:
-		sra->u.adj_sid->sid = sra->nexthop.label;
+		sra->u.adj_sid->sid = sra->input_label;
 		break;
 	default:
 		flog_warn(EC_LIB_DEVELOPMENT, "%s: unexpected circuit type: %u",
@@ -1669,12 +1703,38 @@ static void sr_adj_sid_del(struct sr_adjacency *sra)
 		exit(1);
 	}
 
+	if (sra->type == ISIS_SR_LAN_BACKUP && sra->backup_nexthops) {
+		sra->backup_nexthops->del =
+			(void (*)(void *))isis_nexthop_delete;
+		list_delete(&sra->backup_nexthops);
+	}
+
 	/* Remove Adjacency-SID from the SRDB */
 	listnode_delete(area->srdb.adj_sids, sra);
 	listnode_delete(sra->adj->adj_sids, sra);
 	XFREE(MTYPE_ISIS_SR_INFO, sra);
 }
 
+/**
+ * Lookup Segment Routing Adj-SID by family and type.
+ *
+ * @param adj	  IS-IS Adjacency
+ * @param family  Inet Family (IPv4 or IPv6)
+ * @param type    Adjacency SID type
+ */
+struct sr_adjacency *isis_sr_adj_sid_find(struct isis_adjacency *adj,
+					  int family, enum sr_adj_type type)
+{
+	struct sr_adjacency *sra;
+	struct listnode *node;
+
+	for (ALL_LIST_ELEMENTS_RO(adj->adj_sids, node, sra))
+		if (sra->nexthop.family == family && sra->type == type)
+			return sra;
+
+	return NULL;
+}
+
 /**
  * Remove all Adjacency-SIDs associated to an adjacency that is going down.
  *

isisd/isis_sr.h

@@ -84,13 +84,18 @@ struct sr_adjacency {
 	/* Adjacency type. */
 	enum sr_adj_type type;
 
+	/* Adjacency-SID input label. */
+	mpls_label_t input_label;
+
 	/* Adjacency-SID nexthop information. */
 	struct {
 		int family;
 		union g_addr address;
-		mpls_label_t label;
 	} nexthop;
 
+	/* Adjacency-SID TI-LFA backup nexthops. */
+	struct list *backup_nexthops;
+
 	/* (LAN-)Adjacency-SID Sub-TLV. */
 	union {
 		struct isis_adj_sid *adj_sid;
@@ -277,6 +282,12 @@ extern void isis_sr_prefix_cfg2subtlv(const struct sr_prefix_cfg *pcfg,
 extern void isis_sr_nexthop_update(struct sr_nexthop_info *srnh,
 				   mpls_label_t label);
 extern void isis_sr_nexthop_reset(struct sr_nexthop_info *srnh);
+extern void sr_adj_sid_add_single(struct isis_adjacency *adj, int family,
+				  bool backup, struct list *nexthops);
+extern struct sr_adjacency *isis_sr_adj_sid_find(struct isis_adjacency *adj,
+						 int family,
+						 enum sr_adj_type type);
+extern void isis_area_delete_backup_adj_sids(struct isis_area *area, int level);
 extern void isis_area_verify_sr(struct isis_area *area);
 extern int isis_sr_start(struct isis_area *area);
 extern void isis_sr_stop(struct isis_area *area);

isisd/isis_zebra.c

@@ -471,6 +471,7 @@ void isis_zebra_send_prefix_sid(int cmd, const struct sr_prefix *srp)
  */
 void isis_zebra_send_adjacency_sid(int cmd, const struct sr_adjacency *sra)
 {
+	struct isis *isis = sra->adj->circuit->area->isis;
 	struct zapi_labels zl;
 	struct zapi_nexthop *znh;
 
@@ -482,11 +483,11 @@ void isis_zebra_send_adjacency_sid(int cmd, const struct sr_adjacency *sra)
 
 	sr_debug("  |- %s label %u for interface %s",
 		 cmd == ZEBRA_MPLS_LABELS_ADD ? "Add" : "Delete",
-		 sra->nexthop.label, sra->adj->circuit->interface->name);
+		 sra->input_label, sra->adj->circuit->interface->name);
 
 	memset(&zl, 0, sizeof(zl));
 	zl.type = ZEBRA_LSP_ISIS_SR;
-	zl.local_label = sra->nexthop.label;
+	zl.local_label = sra->input_label;
 	zl.nexthop_num = 1;
 	znh = &zl.nexthops[0];
 	znh->gate = sra->nexthop.address;
@@ -497,6 +498,24 @@ void isis_zebra_send_adjacency_sid(int cmd, const struct sr_adjacency *sra)
 	znh->label_num = 1;
 	znh->labels[0] = MPLS_LABEL_IMPLICIT_NULL;
 
+	/* Set backup nexthops. */
+	if (sra->type == ISIS_SR_LAN_BACKUP) {
+		int count;
+
+		count = isis_zebra_add_nexthops(isis, sra->backup_nexthops,
+						zl.backup_nexthops,
+						ISIS_MPLS_NEXTHOP_BACKUP, 0);
+		if (count > 0) {
+			SET_FLAG(zl.message, ZAPI_LABELS_HAS_BACKUPS);
+			zl.backup_nexthop_num = count;
+
+			SET_FLAG(znh->flags, ZAPI_NEXTHOP_FLAG_HAS_BACKUP);
+			znh->backup_num = count;
+			for (int i = 0; i < count; i++)
+				znh->backup_idx[i] = i;
+		}
+	}
+
 	(void)zebra_send_mpls_labels(zclient, cmd, &zl);
 }