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bgpd: remove dmed check not required in bestpath selection

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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 83ad94694b)
This commit is contained in:
Donald Sharp 2025-02-20 14:28:15 -05:00 committed by Mergify
parent f526b3d8f0
commit 41c3eb672e
1 changed files with 0 additions and 15 deletions
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15
bgpd/bgp_route.c
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@ -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,