bgpd: Store reason why bestpath was choosen

Store in bgp_node the reason why we choose a particular
best path over another.  At this point we do not do
anything other than just store this data when we make
the decision.  Future commits will display it.

Signed-off-by: Donald Sharp <sharpd@cumulusnetworks.com>

diff --git a/bgpd/bgp_route.c b/bgpd/bgp_route.c
index 81917820473595e971c9b620983abce9155d946d..d24a152f138578820a64257cb7b83aa4ef0fe883 100644 (file)
--- a/bgpd/bgp_route.c
+++ b/bgpd/bgp_route.c
@@ -434,7 +434,8 @@ void bgp_path_info_path_with_addpath_rx_str(struct bgp_path_info *pi, char *buf)
 static int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
                             struct bgp_path_info *exist, int *paths_eq,
                             struct bgp_maxpaths_cfg *mpath_cfg, int debug,
-                            char *pfx_buf, afi_t afi, safi_t safi)
+                            char *pfx_buf, afi_t afi, safi_t safi,
+                            enum bgp_path_selection_reason *reason)
 {
        struct attr *newattr, *existattr;
        bgp_peer_sort_t new_sort;
@@ -463,6 +464,7 @@ static int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
 
        /* 0. Null check. */
        if (new == NULL) {
+               *reason = bgp_path_selection_none;
                if (debug)
                        zlog_debug("%s: new is NULL", pfx_buf);
                return 0;
@@ -472,6 +474,7 @@ static int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
                bgp_path_info_path_with_addpath_rx_str(new, new_buf);
 
        if (exist == NULL) {
+               *reason = bgp_path_selection_first;
                if (debug)
                        zlog_debug("%s: %s is the initial bestpath", pfx_buf,
                                   new_buf);
@@ -514,6 +517,7 @@ static int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
                        }
 
                        if (newattr->sticky && !existattr->sticky) {
+                               *reason = bgp_path_selection_evpn_sticky_mac;
                                if (debug)
                                        zlog_debug(
                                                "%s: %s wins over %s due to sticky MAC flag",
@@ -522,6 +526,7 @@ static int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
                        }
 
                        if (!newattr->sticky && existattr->sticky) {
+                               *reason = bgp_path_selection_evpn_sticky_mac;
                                if (debug)
                                        zlog_debug(
                                                "%s: %s loses to %s due to sticky MAC flag",
@@ -534,6 +539,7 @@ static int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
                exist_mm_seq = mac_mobility_seqnum(existattr);
 
                if (new_mm_seq > exist_mm_seq) {
+                       *reason = bgp_path_selection_evpn_seq;
                        if (debug)
                                zlog_debug(
                                        "%s: %s wins over %s due to MM seq %u > %u",
@@ -543,6 +549,7 @@ static int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
                }
 
                if (new_mm_seq < exist_mm_seq) {
+                       *reason = bgp_path_selection_evpn_seq;
                        if (debug)
                                zlog_debug(
                                        "%s: %s loses to %s due to MM seq %u < %u",
@@ -557,6 +564,7 @@ static int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
                 */
                nh_cmp = bgp_path_info_nexthop_cmp(new, exist);
                if (nh_cmp < 0) {
+                       *reason = bgp_path_selection_evpn_lower_ip;
                        if (debug)
                                zlog_debug(
                                        "%s: %s wins over %s due to same MM seq %u and lower IP %s",
@@ -565,6 +573,7 @@ static int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
                        return 1;
                }
                if (nh_cmp > 0) {
+                       *reason = bgp_path_selection_evpn_lower_ip;
                        if (debug)
                                zlog_debug(
                                        "%s: %s loses to %s due to same MM seq %u and higher IP %s",
@@ -579,6 +588,7 @@ static int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
        exist_weight = existattr->weight;
 
        if (new_weight > exist_weight) {
+               *reason = bgp_path_selection_weight;
                if (debug)
                        zlog_debug("%s: %s wins over %s due to weight %d > %d",
                                   pfx_buf, new_buf, exist_buf, new_weight,
@@ -587,6 +597,7 @@ static int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
        }
 
        if (new_weight < exist_weight) {
+               *reason = bgp_path_selection_weight;
                if (debug)
                        zlog_debug("%s: %s loses to %s due to weight %d < %d",
                                   pfx_buf, new_buf, exist_buf, new_weight,
@@ -603,6 +614,7 @@ static int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
                exist_pref = existattr->local_pref;
 
        if (new_pref > exist_pref) {
+               *reason = bgp_path_selection_local_pref;
                if (debug)
                        zlog_debug(
                                "%s: %s wins over %s due to localpref %d > %d",
@@ -612,6 +624,7 @@ static int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
        }
 
        if (new_pref < exist_pref) {
+               *reason = bgp_path_selection_local_pref;
                if (debug)
                        zlog_debug(
                                "%s: %s loses to %s due to localpref %d < %d",
@@ -627,6 +640,7 @@ static int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
         */
        if (!(new->sub_type == BGP_ROUTE_NORMAL ||
              new->sub_type == BGP_ROUTE_IMPORTED)) {
+               *reason = bgp_path_selection_local_route;
                if (debug)
                        zlog_debug(
                                "%s: %s wins over %s due to preferred BGP_ROUTE type",
@@ -636,6 +650,7 @@ static int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
 
        if (!(exist->sub_type == BGP_ROUTE_NORMAL ||
              exist->sub_type == BGP_ROUTE_IMPORTED)) {
+               *reason = bgp_path_selection_local_route;
                if (debug)
                        zlog_debug(
                                "%s: %s loses to %s due to preferred BGP_ROUTE type",
@@ -655,6 +670,7 @@ static int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
                        aspath_hops += aspath_count_confeds(newattr->aspath);
 
                        if (aspath_hops < (exist_hops + exist_confeds)) {
+                               *reason = bgp_path_selection_confed_as_path;
                                if (debug)
                                        zlog_debug(
                                                "%s: %s wins over %s due to aspath (with confeds) hopcount %d < %d",
@@ -665,6 +681,7 @@ static int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
                        }
 
                        if (aspath_hops > (exist_hops + exist_confeds)) {
+                               *reason = bgp_path_selection_confed_as_path;
                                if (debug)
                                        zlog_debug(
                                                "%s: %s loses to %s due to aspath (with confeds) hopcount %d > %d",
@@ -677,6 +694,7 @@ static int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
                        int newhops = aspath_count_hops(newattr->aspath);
 
                        if (newhops < exist_hops) {
+                               *reason = bgp_path_selection_as_path;
                                if (debug)
                                        zlog_debug(
                                                "%s: %s wins over %s due to aspath hopcount %d < %d",
@@ -686,6 +704,7 @@ static int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
                        }
 
                        if (newhops > exist_hops) {
+                               *reason = bgp_path_selection_as_path;
                                if (debug)
                                        zlog_debug(
                                                "%s: %s loses to %s due to aspath hopcount %d > %d",
@@ -698,6 +717,7 @@ static int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
 
        /* 5. Origin check. */
        if (newattr->origin < existattr->origin) {
+               *reason = bgp_path_selection_origin;
                if (debug)
                        zlog_debug("%s: %s wins over %s due to ORIGIN %s < %s",
                                   pfx_buf, new_buf, exist_buf,
@@ -707,6 +727,7 @@ static int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
        }
 
        if (newattr->origin > existattr->origin) {
+               *reason = bgp_path_selection_origin;
                if (debug)
                        zlog_debug("%s: %s loses to %s due to ORIGIN %s > %s",
                                   pfx_buf, new_buf, exist_buf,
@@ -732,6 +753,7 @@ static int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
                exist_med = bgp_med_value(exist->attr, bgp);
 
                if (new_med < exist_med) {
+                       *reason = bgp_path_selection_med;
                        if (debug)
                                zlog_debug(
                                        "%s: %s wins over %s due to MED %d < %d",
@@ -741,6 +763,7 @@ static int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
                }
 
                if (new_med > exist_med) {
+                       *reason = bgp_path_selection_med;
                        if (debug)
                                zlog_debug(
                                        "%s: %s loses to %s due to MED %d > %d",
@@ -756,6 +779,7 @@ static int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
 
        if (new_sort == BGP_PEER_EBGP
            && (exist_sort == BGP_PEER_IBGP || exist_sort == BGP_PEER_CONFED)) {
+               *reason = bgp_path_selection_peer;
                if (debug)
                        zlog_debug(
                                "%s: %s wins over %s due to eBGP peer > iBGP peer",
@@ -765,6 +789,7 @@ static int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
 
        if (exist_sort == BGP_PEER_EBGP
            && (new_sort == BGP_PEER_IBGP || new_sort == BGP_PEER_CONFED)) {
+               *reason = bgp_path_selection_peer;
                if (debug)
                        zlog_debug(
                                "%s: %s loses to %s due to iBGP peer < eBGP peer",
@@ -834,6 +859,7 @@ static int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
        if (CHECK_FLAG(bgp->config, BGP_CONFIG_CONFEDERATION)) {
                if (new_sort == BGP_PEER_CONFED
                    && exist_sort == BGP_PEER_IBGP) {
+                       *reason = bgp_path_selection_confed;
                        if (debug)
                                zlog_debug(
                                        "%s: %s wins over %s due to confed-external peer > confed-internal peer",
@@ -843,6 +869,7 @@ static int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
 
                if (exist_sort == BGP_PEER_CONFED
                    && new_sort == BGP_PEER_IBGP) {
+                       *reason = bgp_path_selection_confed;
                        if (debug)
                                zlog_debug(
                                        "%s: %s loses to %s due to confed-internal peer < confed-external peer",
@@ -918,6 +945,7 @@ static int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
                                        "%s: %s loses to %s after IGP metric comparison",
                                        pfx_buf, new_buf, exist_buf);
                }
+               *reason = bgp_path_selection_igp_metric;
                return ret;
        }
 
@@ -928,6 +956,7 @@ static int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
        if (!bgp_flag_check(bgp, BGP_FLAG_COMPARE_ROUTER_ID)
            && new_sort == BGP_PEER_EBGP && exist_sort == BGP_PEER_EBGP) {
                if (CHECK_FLAG(new->flags, BGP_PATH_SELECTED)) {
+                       *reason = bgp_path_selection_older;
                        if (debug)
                                zlog_debug(
                                        "%s: %s wins over %s due to oldest external",
@@ -936,6 +965,7 @@ static int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
                }
 
                if (CHECK_FLAG(exist->flags, BGP_PATH_SELECTED)) {
+                       *reason = bgp_path_selection_older;
                        if (debug)
                                zlog_debug(
                                        "%s: %s loses to %s due to oldest external",
@@ -959,6 +989,7 @@ static int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
                exist_id.s_addr = exist->peer->remote_id.s_addr;
 
        if (ntohl(new_id.s_addr) < ntohl(exist_id.s_addr)) {
+               *reason = bgp_path_selection_router_id;
                if (debug)
                        zlog_debug(
                                "%s: %s wins over %s due to Router-ID comparison",
@@ -967,6 +998,7 @@ static int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
        }
 
        if (ntohl(new_id.s_addr) > ntohl(exist_id.s_addr)) {
+               *reason = bgp_path_selection_router_id;
                if (debug)
                        zlog_debug(
                                "%s: %s loses to %s due to Router-ID comparison",
@@ -979,6 +1011,7 @@ static int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
        exist_cluster = BGP_CLUSTER_LIST_LENGTH(exist->attr);
 
        if (new_cluster < exist_cluster) {
+               *reason = bgp_path_selection_cluster_length;
                if (debug)
                        zlog_debug(
                                "%s: %s wins over %s due to CLUSTER_LIST length %d < %d",
@@ -988,6 +1021,7 @@ static int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
        }
 
        if (new_cluster > exist_cluster) {
+               *reason = bgp_path_selection_cluster_length;
                if (debug)
                        zlog_debug(
                                "%s: %s loses to %s due to CLUSTER_LIST length %d > %d",
@@ -1001,6 +1035,7 @@ static int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
         * valid peer information (as the connection may or may not be up).
         */
        if (CHECK_FLAG(exist->flags, BGP_PATH_STALE)) {
+               *reason = bgp_path_selection_stale;
                if (debug)
                        zlog_debug(
                                "%s: %s wins over %s due to latter path being STALE",
@@ -1009,6 +1044,7 @@ static int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
        }
 
        if (CHECK_FLAG(new->flags, BGP_PATH_STALE)) {
+               *reason = bgp_path_selection_stale;
                if (debug)
                        zlog_debug(
                                "%s: %s loses to %s due to former path being STALE",
@@ -1017,14 +1053,19 @@ static int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
        }
 
        /* locally configured routes to advertise do not have su_remote */
-       if (new->peer->su_remote == NULL)
+       if (new->peer->su_remote == NULL) {
+               *reason = bgp_path_selection_local_configured;
                return 0;
-       if (exist->peer->su_remote == NULL)
+       }
+       if (exist->peer->su_remote == NULL) {
+               *reason = bgp_path_selection_local_configured;
                return 1;
+       }
 
        ret = sockunion_cmp(new->peer->su_remote, exist->peer->su_remote);
 
        if (ret == 1) {
+               *reason = bgp_path_selection_neighbor_ip;
                if (debug)
                        zlog_debug(
                                "%s: %s loses to %s due to Neighor IP comparison",
@@ -1033,6 +1074,7 @@ static int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
        }
 
        if (ret == -1) {
+               *reason = bgp_path_selection_neighbor_ip;
                if (debug)
                        zlog_debug(
                                "%s: %s wins over %s due to Neighor IP comparison",
@@ -1040,6 +1082,7 @@ static int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
                return 1;
        }
 
+       *reason = bgp_path_selection_default;
        if (debug)
                zlog_debug("%s: %s wins over %s due to nothing left to compare",
                           pfx_buf, new_buf, exist_buf);
@@ -1053,12 +1096,13 @@ static int bgp_path_info_cmp(struct bgp *bgp, struct bgp_path_info *new,
  * This version is compatible with */
 int bgp_path_info_cmp_compatible(struct bgp *bgp, struct bgp_path_info *new,
                                 struct bgp_path_info *exist, char *pfx_buf,
-                                afi_t afi, safi_t safi)
+                                afi_t afi, safi_t safi,
+                                enum bgp_path_selection_reason *reason)
 {
        int paths_eq;
        int ret;
        ret = bgp_path_info_cmp(bgp, new, exist, &paths_eq, NULL, 0, pfx_buf,
-                               afi, safi);
+                               afi, safi, reason);
 
        if (paths_eq)
                ret = 0;
@@ -1955,7 +1999,8 @@ void bgp_best_selection(struct bgp *bgp, struct bgp_node *rn,
                                        if (bgp_path_info_cmp(
                                                    bgp, pi2, new_select,
                                                    &paths_eq, mpath_cfg, debug,
-                                                   pfx_buf, afi, safi)) {
+                                                   pfx_buf, afi, safi,
+                                                   &rn->reason)) {
                                                bgp_path_info_unset_flag(
                                                        rn, new_select,
                                                        BGP_PATH_DMED_SELECTED);
@@ -2028,7 +2073,7 @@ void bgp_best_selection(struct bgp *bgp, struct bgp_node *rn,
                bgp_path_info_unset_flag(rn, pi, BGP_PATH_DMED_CHECK);
 
                if (bgp_path_info_cmp(bgp, pi, new_select, &paths_eq, mpath_cfg,
-                                     debug, pfx_buf, afi, safi)) {
+                                     debug, pfx_buf, afi, safi, &rn->reason)) {
                        new_select = pi;
                }
        }
@@ -2084,7 +2129,8 @@ void bgp_best_selection(struct bgp *bgp, struct bgp_node *rn,
                        }
 
                        bgp_path_info_cmp(bgp, pi, new_select, &paths_eq,
-                                         mpath_cfg, debug, pfx_buf, afi, safi);
+                                         mpath_cfg, debug, pfx_buf, afi, safi,
+                                         &rn->reason);
 
                        if (paths_eq) {
                                if (debug)

diff --git a/bgpd/bgp_route.h b/bgpd/bgp_route.h
index 0d16ffc90c35b875633777d8e34ffa12db89d274..f7150844509704e199fc85ab273e197997cd2f25 100644 (file)
--- a/bgpd/bgp_route.h
+++ b/bgpd/bgp_route.h
@@ -588,7 +588,8 @@ extern void bgp_path_info_restore(struct bgp_node *rn,
 extern int bgp_path_info_cmp_compatible(struct bgp *bgp,
                                        struct bgp_path_info *new,
                                        struct bgp_path_info *exist,
-                                       char *pfx_buf, afi_t afi, safi_t safi);
+                                       char *pfx_buf, afi_t afi, safi_t safi,
+                                       enum bgp_path_selection_reason *reason);
 extern void bgp_attr_add_gshut_community(struct attr *attr);
 
 extern void bgp_best_selection(struct bgp *bgp, struct bgp_node *rn,

diff --git a/bgpd/bgp_table.h b/bgpd/bgp_table.h
index 040e83a8cd9e8a92ca278759f89cf27967137209..b3542e7848a9b11f632d8a90013d5cfecd4e7d54 100644 (file)
--- a/bgpd/bgp_table.h
+++ b/bgpd/bgp_table.h
@@ -42,6 +42,31 @@ struct bgp_table {
        uint64_t version;
 };
 
+enum bgp_path_selection_reason {
+       bgp_path_selection_none,
+       bgp_path_selection_first,
+       bgp_path_selection_evpn_sticky_mac,
+       bgp_path_selection_evpn_seq,
+       bgp_path_selection_evpn_lower_ip,
+       bgp_path_selection_weight,
+       bgp_path_selection_local_pref,
+       bgp_path_selection_local_route,
+       bgp_path_selection_confed_as_path,
+       bgp_path_selection_as_path,
+       bgp_path_selection_origin,
+       bgp_path_selection_med,
+       bgp_path_selection_peer,
+       bgp_path_selection_confed,
+       bgp_path_selection_igp_metric,
+       bgp_path_selection_older,
+       bgp_path_selection_router_id,
+       bgp_path_selection_cluster_length,
+       bgp_path_selection_stale,
+       bgp_path_selection_local_configured,
+       bgp_path_selection_neighbor_ip,
+       bgp_path_selection_default,
+};
+
 struct bgp_node {
        /*
         * CAUTION
@@ -72,6 +97,8 @@ struct bgp_node {
 #define BGP_NODE_REGISTERED_FOR_LABEL   (1 << 3)
 
        struct bgp_addpath_node_data tx_addpath;
+
+       enum bgp_path_selection_reason reason;
 };
 
 /*

diff --git a/bgpd/rfapi/rfapi_import.c b/bgpd/rfapi/rfapi_import.c
index d67361620db84c0967e5e91e8a740dfd4099de45..ad0900c2b8543f0b8e8f915211812ea84d50a918 100644 (file)
--- a/bgpd/rfapi/rfapi_import.c
+++ b/bgpd/rfapi/rfapi_import.c
@@ -1984,11 +1984,14 @@ static void rfapiBgpInfoAttachSorted(struct agg_node *rn,
 
        for (prev = NULL, next = rn->info; next;
             prev = next, next = next->next) {
+               enum bgp_path_selection_reason reason;
+
                if (!bgp
                    || (!CHECK_FLAG(info_new->flags, BGP_PATH_REMOVED)
                        && CHECK_FLAG(next->flags, BGP_PATH_REMOVED))
                    || bgp_path_info_cmp_compatible(bgp, info_new, next,
-                                                   pfx_buf, afi, safi)
+                                                   pfx_buf, afi, safi,
+                                                   &reason)
                               == -1) { /* -1 if 1st is better */
                        break;
                }