bgpd: Derive and set MED from IGP or AIGP

bgpd/bgp_attr.c

@@ -1177,8 +1177,7 @@ struct attr *bgp_attr_aggregate_intern(
 	SET_FLAG(attr.flag, ATTR_FLAG_BIT(BGP_ATTR_ORIGIN));
 
 	/* MED */
-	attr.med = 0;
-	SET_FLAG(attr.flag, ATTR_FLAG_BIT(BGP_ATTR_MULTI_EXIT_DISC));
+	bgp_attr_set_med(&attr, 0);
 
 	/* AS path attribute. */
 	if (aspath)
@@ -1933,9 +1932,7 @@ static enum bgp_attr_parse_ret bgp_attr_med(struct bgp_attr_parser_args *args)
 					  args->total);
 	}
 
-	attr->med = stream_getl(peer->curr);
-
-	SET_FLAG(attr->flag, ATTR_FLAG_BIT(BGP_ATTR_MULTI_EXIT_DISC));
+	bgp_attr_set_med(attr, stream_getl(peer->curr));
 
 	return BGP_ATTR_PARSE_PROCEED;
 }

bgpd/bgp_attr.h

@@ -608,6 +608,12 @@ static inline uint64_t bgp_aigp_metric_total(struct bgp_path_info *bpi)
 		return aigp;
 }
 
+static inline void bgp_attr_set_med(struct attr *attr, uint32_t med)
+{
+	attr->med = med;
+	SET_FLAG(attr->flag, ATTR_FLAG_BIT(BGP_ATTR_MULTI_EXIT_DISC));
+}
+
 static inline struct cluster_list *bgp_attr_get_cluster(const struct attr *attr)
 {
 	return attr->cluster1;

bgpd/bgp_route.c

@@ -3727,11 +3727,10 @@ static void bgp_process_main_one(struct bgp *bgp, struct bgp_dest *dest,
 
 		/* If there is a change of interest to peers, reannounce the
 		 * route. */
-		if (CHECK_FLAG(old_select->flags, BGP_PATH_ATTR_CHANGED)
-		    || CHECK_FLAG(old_select->flags, BGP_PATH_LINK_BW_CHG)
-		    || CHECK_FLAG(dest->flags, BGP_NODE_LABEL_CHANGED)) {
+		if (CHECK_FLAG(old_select->flags, BGP_PATH_ATTR_CHANGED) ||
+		    CHECK_FLAG(dest->flags, BGP_NODE_LABEL_CHANGED) ||
+		    bgp_zebra_has_route_changed(old_select)) {
 			group_announce_route(bgp, afi, safi, dest, new_select);
-
 			/* unicast routes must also be annouced to
 			 * labeled-unicast update-groups */
 			if (safi == SAFI_UNICAST)
@@ -6747,8 +6746,8 @@ void bgp_static_update(struct bgp *bgp, const struct prefix *p,
 	bgp_attr_default_set(&attr, bgp, BGP_ORIGIN_IGP);
 
 	attr.nexthop = bgp_static->igpnexthop;
-	attr.med = bgp_static->igpmetric;
-	attr.flag |= ATTR_FLAG_BIT(BGP_ATTR_MULTI_EXIT_DISC);
+
+	bgp_attr_set_med(&attr, bgp_static->igpmetric);
 
 	if (afi == AFI_IP)
 		attr.mp_nexthop_len = BGP_ATTR_NHLEN_IPV4;
@@ -9015,9 +9014,8 @@ void bgp_redistribute_add(struct bgp *bgp, struct prefix *p,
 	else
 		UNSET_FLAG(attr.nh_flags, BGP_ATTR_NH_IF_OPERSTATE);
 
-	attr.med = metric;
+	bgp_attr_set_med(&attr, metric);
 	attr.distance = distance;
-	attr.flag |= ATTR_FLAG_BIT(BGP_ATTR_MULTI_EXIT_DISC);
 	attr.tag = tag;
 
 	if (metric)

bgpd/bgp_routemap.c

@@ -125,6 +125,10 @@ o Local extensions
 #define RMAP_VALUE_ADD 1
 #define RMAP_VALUE_SUB 2
 
+#define RMAP_VALUE_TYPE_RTT  1
+#define RMAP_VALUE_TYPE_IGP  2
+#define RMAP_VALUE_TYPE_AIGP 3
+
 struct rmap_value {
 	uint8_t action;
 	uint8_t variable;
@@ -140,14 +144,21 @@ static int route_value_match(struct rmap_value *rv, uint32_t value)
 }
 
 static uint32_t route_value_adjust(struct rmap_value *rv, uint32_t current,
-				   struct peer *peer)
+				   struct bgp_path_info *bpi)
 {
 	uint32_t value;
+	struct peer *peer = bpi->peer;
 
 	switch (rv->variable) {
-	case 1:
+	case RMAP_VALUE_TYPE_RTT:
 		value = peer->rtt;
 		break;
+	case RMAP_VALUE_TYPE_IGP:
+		value = bpi->extra ? bpi->extra->igpmetric : 0;
+		break;
+	case RMAP_VALUE_TYPE_AIGP:
+		value = MIN(bpi->attr->aigp_metric, UINT32_MAX);
+		break;
 	default:
 		value = rv->value;
 		break;
@@ -187,11 +198,14 @@ static void *route_value_compile(const char *arg)
 		larg = strtoul(arg, &endptr, 10);
 		if (*arg == 0 || *endptr != 0 || errno || larg > UINT32_MAX)
 			return NULL;
+	} else if (strmatch(arg, "rtt")) {
+		var = RMAP_VALUE_TYPE_RTT;
+	} else if (strmatch(arg, "igp")) {
+		var = RMAP_VALUE_TYPE_IGP;
+	} else if (strmatch(arg, "aigp")) {
+		var = RMAP_VALUE_TYPE_AIGP;
 	} else {
-		if (strcmp(arg, "rtt") == 0)
-			var = 1;
-		else
-			return NULL;
+		return NULL;
 	}
 
 	rv = XMALLOC(MTYPE_ROUTE_MAP_COMPILED, sizeof(struct rmap_value));
@@ -2145,7 +2159,7 @@ route_set_local_pref(void *rule, const struct prefix *prefix, void *object)
 		locpref = path->attr->local_pref;
 
 	path->attr->flag |= ATTR_FLAG_BIT(BGP_ATTR_LOCAL_PREF);
-	path->attr->local_pref = route_value_adjust(rv, locpref, path->peer);
+	path->attr->local_pref = route_value_adjust(rv, locpref, path);
 
 	return RMAP_OKAY;
 }
@@ -2172,7 +2186,7 @@ route_set_weight(void *rule, const struct prefix *prefix, void *object)
 	path = object;
 
 	/* Set weight value. */
-	path->attr->weight = route_value_adjust(rv, 0, path->peer);
+	path->attr->weight = route_value_adjust(rv, 0, path);
 
 	return RMAP_OKAY;
 }
@@ -2222,8 +2236,7 @@ route_set_metric(void *rule, const struct prefix *prefix, void *object)
 	if (path->attr->flag & ATTR_FLAG_BIT(BGP_ATTR_MULTI_EXIT_DISC))
 		med = path->attr->med;
 
-	path->attr->med = route_value_adjust(rv, med, path->peer);
-	path->attr->flag |= ATTR_FLAG_BIT(BGP_ATTR_MULTI_EXIT_DISC);
+	bgp_attr_set_med(path->attr, route_value_adjust(rv, med, path));
 
 	return RMAP_OKAY;
 }

bgpd/bgp_updgrp_adv.c

@@ -906,8 +906,8 @@ void subgroup_default_originate(struct update_subgroup *subgrp, bool withdraw)
 	assert(attr.aspath);
 
 	aspath = attr.aspath;
-	attr.med = 0;
-	attr.flag |= ATTR_FLAG_BIT(BGP_ATTR_MULTI_EXIT_DISC);
+
+	bgp_attr_set_med(&attr, 0);
 
 	if ((afi == AFI_IP6) || peer_cap_enhe(peer, afi, safi)) {
 		/* IPv6 global nexthop must be included. */

bgpd/rfapi/rfapi.c

@@ -667,10 +667,8 @@ void add_vnc_route(struct rfapi_descriptor *rfd, /* cookie, VPN UN addr, peer */
 		attr.flag |= ATTR_FLAG_BIT(BGP_ATTR_LOCAL_PREF);
 	}
 
-	if (med) {
-		attr.med = *med;
-		attr.flag |= ATTR_FLAG_BIT(BGP_ATTR_MULTI_EXIT_DISC);
-	}
+	if (med)
+		bgp_attr_set_med(&attr, *med);
 
 	/* override default weight assigned by bgp_attr_default_set() */
 	attr.weight = rfd->peer ? rfd->peer->weight[afi][safi] : 0;
@@ -863,10 +861,8 @@ void add_vnc_route(struct rfapi_descriptor *rfd, /* cookie, VPN UN addr, peer */
 
 	red = bgp_redist_lookup(bgp, afi, type, 0);
 
-	if (red && red->redist_metric_flag) {
-		attr.med = red->redist_metric;
-		attr.flag |= ATTR_FLAG_BIT(BGP_ATTR_MULTI_EXIT_DISC);
-	}
+	if (red && red->redist_metric_flag)
+		bgp_attr_set_med(&attr, red->redist_metric);
 
 	bn = bgp_afi_node_get(bgp->rib[afi][safi], afi, safi, p, prd);
 

bgpd/rfapi/vnc_export_bgp.c

@@ -96,15 +96,16 @@ static void encap_attr_export_ce(struct attr *new, struct attr *orig,
 	 *          neighbor NEIGHBOR attribute-unchanged med
 	 */
 	if (!CHECK_FLAG(new->flag, BGP_ATTR_MULTI_EXIT_DISC)) {
+		uint32_t med = 255;
+
 		if (CHECK_FLAG(new->flag, BGP_ATTR_LOCAL_PREF)) {
 			if (new->local_pref > 255)
-				new->med = 0;
+				med = 0;
 			else
-				new->med = 255 - new->local_pref;
-		} else {
-			new->med = 255; /* shouldn't happen */
+				med = 255 - new->local_pref;
 		}
-		new->flag |= ATTR_FLAG_BIT(BGP_ATTR_MULTI_EXIT_DISC);
+
+		bgp_attr_set_med(new, med);
 	}
 
 	/*
@@ -642,15 +643,16 @@ encap_attr_export(struct attr *new, struct attr *orig,
 	 *          neighbor NEIGHBOR attribute-unchanged med
 	 */
 	if (!CHECK_FLAG(new->flag, BGP_ATTR_MULTI_EXIT_DISC)) {
+		uint32_t med = 255;
+
 		if (CHECK_FLAG(new->flag, BGP_ATTR_LOCAL_PREF)) {
 			if (new->local_pref > 255)
-				new->med = 0;
+				med = 0;
 			else
-				new->med = 255 - new->local_pref;
-		} else {
-			new->med = 255; /* shouldn't happen */
+				med = 255 - new->local_pref;
 		}
-		new->flag |= ATTR_FLAG_BIT(BGP_ATTR_MULTI_EXIT_DISC);
+
+		bgp_attr_set_med(new, med);
 	}
 
 	/*

doc/user/routemap.rst

@@ -305,13 +305,18 @@ Route Map Set Command
 
    Set the route's weight.
 
-.. clicmd:: set metric <[+|-](1-4294967295)|rtt|+rtt|-rtt>
+.. clicmd:: set metric <[+|-](1-4294967295)|rtt|+rtt|-rtt|igp|aigp>
 
    Set the route metric. When used with BGP, set the BGP attribute MED to a
    specific value. Use `+`/`-` to add or subtract the specified value to/from
    the existing/MED. Use `rtt` to set the MED to the round trip time or
    `+rtt`/`-rtt` to add/subtract the round trip time to/from the MED.
 
+   If ``igp`` is specified, then the actual value from the IGP protocol is used.
+
+   If ``aigp`` is specified, then the actual value from the AIGP metric is used
+   (encoded as MED instead of AIGP attribute).
+
 .. clicmd:: set min-metric <(0-4294967295)>
 
    Set the minimum metric for the route.

lib/routemap_cli.c

@@ -922,13 +922,15 @@ DEFPY_YANG(
 
 DEFPY_YANG(
 	set_metric, set_metric_cmd,
-	"set metric <(-4294967295-4294967295)$metric|rtt$rtt|+rtt$artt|-rtt$srtt>",
+	"set metric <(-4294967295-4294967295)$metric|rtt$rtt|+rtt$artt|-rtt$srtt|igp$igp|aigp$aigp>",
 	SET_STR
 	"Metric value for destination routing protocol\n"
 	"Metric value (use +/- for additions or subtractions)\n"
 	"Assign round trip time\n"
 	"Add round trip time\n"
-	"Subtract round trip time\n")
+	"Subtract round trip time\n"
+	"Metric value from IGP protocol\n"
+	"Metric value from AIGP (Accumulated IGP)\n")
 {
 	const char *xpath = "./set-action[action='frr-route-map:set-metric']";
 	char xpath_value[XPATH_MAXLEN];
@@ -939,6 +941,12 @@ DEFPY_YANG(
 		snprintf(xpath_value, sizeof(xpath_value),
 			 "%s/rmap-set-action/use-round-trip-time", xpath);
 		snprintf(value, sizeof(value), "true");
+	} else if (igp) {
+		snprintf(xpath_value, sizeof(xpath_value), "%s/rmap-set-action/use-igp", xpath);
+		snprintf(value, sizeof(value), "true");
+	} else if (aigp) {
+		snprintf(xpath_value, sizeof(xpath_value), "%s/rmap-set-action/use-aigp", xpath);
+		snprintf(value, sizeof(value), "true");
 	} else if (artt) {
 		snprintf(xpath_value, sizeof(xpath_value),
 			 "%s/rmap-set-action/add-round-trip-time", xpath);
@@ -1148,23 +1156,19 @@ void route_map_action_show(struct vty *vty, const struct lyd_node *dnode,
 		if (yang_dnode_get(dnode,
 				   "./rmap-set-action/use-round-trip-time")) {
 			vty_out(vty, " set metric rtt\n");
-		} else if (yang_dnode_get(
-				   dnode,
-				   "./rmap-set-action/add-round-trip-time")) {
+		} else if (yang_dnode_get(dnode, "./rmap-set-action/use-igp")) {
+			vty_out(vty, " set metric igp\n");
+		} else if (yang_dnode_get(dnode, "./rmap-set-action/use-aigp")) {
+			vty_out(vty, " set metric aigp\n");
+		} else if (yang_dnode_get(dnode, "./rmap-set-action/add-round-trip-time")) {
 			vty_out(vty, " set metric +rtt\n");
-		} else if (
-			yang_dnode_get(
-				dnode,
-				"./rmap-set-action/subtract-round-trip-time")) {
+		} else if (yang_dnode_get(dnode, "./rmap-set-action/subtract-round-trip-time")) {
 			vty_out(vty, " set metric -rtt\n");
-		} else if (yang_dnode_get(dnode,
-					  "./rmap-set-action/add-metric")) {
+		} else if (yang_dnode_get(dnode, "./rmap-set-action/add-metric")) {
 			vty_out(vty, " set metric +%s\n",
 				yang_dnode_get_string(
 					dnode, "./rmap-set-action/add-metric"));
-		} else if (yang_dnode_get(
-				   dnode,
-				   "./rmap-set-action/subtract-metric")) {
+		} else if (yang_dnode_get(dnode, "./rmap-set-action/subtract-metric")) {
 			vty_out(vty, " set metric -%s\n",
 				yang_dnode_get_string(
 					dnode,

lib/routemap_northbound.c

@@ -1213,6 +1213,34 @@ static int lib_route_map_entry_set_action_use_round_trip_time_destroy(
 	return lib_route_map_entry_set_action_value_destroy(args);
 }
 
+/*
+ * XPath: /frr-route-map:lib/route-map/entry/set-action/use-igp
+ */
+static int lib_route_map_entry_set_action_use_igp_modify(struct nb_cb_modify_args *args)
+{
+	return set_action_modify(args->event, args->dnode, args->resource, "igp", args->errmsg,
+				 args->errmsg_len);
+}
+
+static int lib_route_map_entry_set_action_use_igp_destroy(struct nb_cb_destroy_args *args)
+{
+	return lib_route_map_entry_set_action_value_destroy(args);
+}
+
+/*
+ * XPath: /frr-route-map:lib/route-map/entry/set-action/use-aigp
+ */
+static int lib_route_map_entry_set_action_use_aigp_modify(struct nb_cb_modify_args *args)
+{
+	return set_action_modify(args->event, args->dnode, args->resource, "aigp", args->errmsg,
+				 args->errmsg_len);
+}
+
+static int lib_route_map_entry_set_action_use_aigp_destroy(struct nb_cb_destroy_args *args)
+{
+	return lib_route_map_entry_set_action_value_destroy(args);
+}
+
 /*
  * XPath: /frr-route-map:lib/route-map/entry/set-action/add-round-trip-time
  */
@@ -1516,6 +1544,20 @@ const struct frr_yang_module_info frr_route_map_info = {
 				.destroy = lib_route_map_entry_set_action_use_round_trip_time_destroy,
 			}
 		},
+		{
+			.xpath = "/frr-route-map:lib/route-map/entry/set-action/rmap-set-action/use-igp",
+			.cbs = {
+				.modify = lib_route_map_entry_set_action_use_igp_modify,
+				.destroy = lib_route_map_entry_set_action_use_igp_destroy,
+			}
+		},
+		{
+			.xpath = "/frr-route-map:lib/route-map/entry/set-action/rmap-set-action/use-aigp",
+			.cbs = {
+				.modify = lib_route_map_entry_set_action_use_aigp_modify,
+				.destroy = lib_route_map_entry_set_action_use_aigp_destroy,
+			}
+		},
 		{
 			.xpath = "/frr-route-map:lib/route-map/entry/set-action/rmap-set-action/add-round-trip-time",
 			.cbs = {

tests/topotests/bgp_aigp/r1/bgpd.conf

@@ -9,4 +9,20 @@ router bgp 65001
  neighbor 10.0.0.3 timers 1 3
  neighbor 10.0.0.3 timers connect 1
  neighbor 10.0.0.3 update-source lo
+ neighbor 192.168.18.8 remote-as external
+ neighbor 192.168.18.8 timers 1 3
+ neighbor 192.168.18.8 timers connect 1
+ address-family ipv4
+  neighbor 192.168.18.8 route-map r8 out
+ exit-address-family
 !
+ip prefix-list p71 seq 5 permit 10.0.0.71/32
+ip prefix-list p72 seq 5 permit 10.0.0.72/32
+!
+route-map r8 permit 10
+ match ip address prefix-list p71
+ set metric igp
+route-map r8 permit 20
+ match ip address prefix-list p72
+ set metric aigp
+exit