From: vivek <vivek@cumulusnetworks.com>
Date: Thu, 3 Dec 2020 04:04:19 +0000 (-0800)
Subject: bgpd: Fix deterministic-med check for stale paths
X-Git-Tag: frr-8.4.3~11^2~2
X-Git-Url: https://git.puffer.fish/?a=commitdiff_plain;h=38efc4b35e43fa2b6ad2a6d4bb41f3fcb3a5d559;p=mirror%2Ffrr.git

bgpd: Fix deterministic-med check for stale paths

When performing deterministic MED processing, ensure that the peer
status is not checked when we encounter a stale path. Otherwise, this
path will be skipped from the DMED consideration leading to it potentially
not being installed.

Test scenario: Consider a prefix with 2 (multi)paths. The peer that
announces the path with the winning DMED undergoes a graceful-restart.
Before it comes back up, the other path goes away. Prior to the fix, a
third router that receives both these paths would have ended up not
having any path installed to the prefix after the above events.

Signed-off-by: Vivek Venkatraman <vivek@nvidia.com>

For internal use:
Ticket: CM-32032
Testing done: Multiple manual testing

(cherry picked from commit de692a4ebe0b8ea8e191d8ac1f3b41a386edd577)
---

diff --git a/bgpd/bgp_route.c b/bgpd/bgp_route.c
index 29e2768d17..501e169b05 100644
--- a/bgpd/bgp_route.c
+++ b/bgpd/bgp_route.c
@@ -2590,9 +2590,12 @@ void bgp_best_selection(struct bgp *bgp, struct bgp_dest *dest,
 				continue;
 			if (BGP_PATH_HOLDDOWN(pi1))
 				continue;
-			if (pi1->peer != bgp->peer_self)
+			if (pi1->peer != bgp->peer_self &&
+			    !CHECK_FLAG(pi1->peer->sflags,
+					PEER_STATUS_NSF_WAIT)) {
 				if (!peer_established(pi1->peer))
 					continue;
+			}
 
 			new_select = pi1;
 			if (pi1->next) {