bgpd: remove dmed check not required in bestpath selection

As part of the upstream master commit (f3575f61c7 bgpd: Sort the
bgp_path_inf) the snippet of the code for dmed check condition
left out, which leads to an issue of selecting incorrect bestpath.

As an example:

During the bestpath selection local route looses to another path due
to dmed condition being hit.

The snippet of the logs:

2025/02/20 03:06:20.131441 BGP: [JW7VP-K1YVV]
[2]:[0]:[48]:[00:92:00:00:00:10](VRF default): Comparing path
27.0.0.7 flags Valid  with path Static announcement flags Selected Valid Attr Changed Unsorted
2025/02/20 03:06:20.131445 BGP: [SYTDR-QV6X9] [2]:[0]:[48]:[00:92:00:00:00:10]: path 27.0.0.7 loses to path Static announcement as ES 03:44:38:39:ff:ff:02:00:00:01 is same and local
2025/02/20 03:06:20.131452 BGP: [JW7VP-K1YVV] [2]:[0]:[48]:[00:92:00:00:00:10](VRF default): Comparing path 27.0.0.8 flags Valid  with path Static announcement flags Selected Valid Attr Changed Unsorted
2025/02/20 03:06:20.131456 BGP: [SYTDR-QV6X9] [2]:[0]:[48]:[00:92:00:00:00:10]: path 27.0.0.8 loses to path Static announcement as ES 03:44:38:39:ff:ff:02:00:00:01 is same and local
2025/02/20 03:06:20.131458 BGP: [WEWEC-8SE72] [2]:[0]:[48]:[00:92:00:00:00:10](VRF default): path Static announcement is the bestpath from AS 0   <<<< static is best
2025/02/20 03:06:20.131463 BGP: [Z3A78-GM3G5] bgp_best_selection: [2]:[0]:[48]:[00:92:00:00:00:10](VRF default) pi 27.0.0.7 dmed
2025/02/20 03:06:20.131467 BGP: [Z3A78-GM3G5] bgp_best_selection: [2]:[0]:[48]:[00:92:00:00:00:10](VRF default) pi 27.0.0.8 dmed
2025/02/20 03:06:20.131471 BGP: [N6CTF-2RSKS] [2]:[0]:[48]:[00:92:00:00:00:10](VRF default): After path selection, newbest is path 27.0.0.7 oldbest was Static announce

Signed-off-by: Donald Sharp <sharpd@nvidia.com>
(cherry picked from commit 83ad94694bc061e1ff5f43db42cba46320e0df73)

diff --git a/bgpd/bgp_route.c b/bgpd/bgp_route.c
index de8c5c8ab045b1ee5179d78e571d379c47ff78db..a12fe28ad2eb86805b8c48efc5566c4b17be24c1 100644 (file)
--- a/bgpd/bgp_route.c
+++ b/bgpd/bgp_route.c
@@ -3135,21 +3135,6 @@ void bgp_best_selection(struct bgp *bgp, struct bgp_dest *dest,
 
                        bgp_path_info_unset_flag(dest, look_thru,
                                                 BGP_PATH_DMED_CHECK);
-                       if (CHECK_FLAG(bgp->flags, BGP_FLAG_DETERMINISTIC_MED) &&
-                           (!CHECK_FLAG(look_thru->flags,
-                                        BGP_PATH_DMED_SELECTED))) {
-                               bgp_path_info_unset_flag(dest, look_thru,
-                                                        BGP_PATH_DMED_CHECK);
-                               if (debug)
-                                       zlog_debug("%s: %pBD(%s) pi %s dmed",
-                                                  __func__, dest,
-                                                  bgp->name_pretty,
-                                                  look_thru->peer->host);
-
-                               worse = look_thru;
-                               continue;
-                       }
-
                        reason = dest->reason;
                        any_comparisons = true;
                        if (bgp_path_info_cmp(bgp, first, look_thru, &paths_eq,