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Revert "bgpd: upon if event, evaluate bnc with matching nexthop"

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This reverts commit 58592be577.

This commit is being reverted because of several issues:

a) tcpdump -i <any interface that bgp happens to use>

This command causes bgp to dump it's entire table to all
of it's peers again.  This is a huge problem in any type
of scaled environment *and* it is not unusual to have an
operator do this.

b) This commit appears to be attempting to solve the problem
with route leaking across vrf's using labels( or somesuch ).
Unfortunately we have absolutely no topotests that show the
behavior.  I am also unable to get any type of how to reproduce
the problem being solved by the commit.  I do know, though,
that the problem really stems from the fact that bgp has
decided to cheat and not create bnc's for route leaking.
Thus when a nexthop changes, bgp is not being notified.
This commit was being used as a hammer to solve the problem.

While I do agree backing out a bug fix for some operator
is less then ideal, I believe that since I cannot get the
operator to tell me the problem it solved and the fact
that sending large amounts of updates with just a simple
tcpdump command ( actually 2 one for tcpdump start and
one for finishing ) is more detrimental in my eyes at
this point in time.  Additionally the solution used
is the wrong one for the problem.

Signed-off-by: Donald Sharp <sharpd@nvidia.com>
This commit is contained in:
Donald Sharp 2025-03-12 09:01:52 -04:00
parent 27953dd141
commit 052aea624e
1 changed files with 1 additions and 39 deletions
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40
bgpd/bgp_nht.c
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@ -763,10 +763,6 @@ static void bgp_nht_ifp_table_handle(struct bgp *bgp,
struct interface *ifp, bool up)
{
struct bgp_nexthop_cache *bnc;
struct nexthop *nhop;
uint16_t other_nh_count;
bool nhop_ll_found = false;
bool nhop_found = false;
if (ifp->ifindex == IFINDEX_INTERNAL) {
zlog_warn("%s: The interface %s ignored", __func__, ifp->name);
@ -774,42 +770,9 @@ static void bgp_nht_ifp_table_handle(struct bgp *bgp,
}
frr_each (bgp_nexthop_cache, table, bnc) {
other_nh_count = 0;
nhop_ll_found = bnc->ifindex_ipv6_ll == ifp->ifindex;
for (nhop = bnc->nexthop; nhop; nhop = nhop->next) {
if (nhop->ifindex == bnc->ifindex_ipv6_ll)
if (bnc->ifindex_ipv6_ll != ifp->ifindex)
continue;
if (nhop->ifindex != ifp->ifindex) {
other_nh_count++;
continue;
}
if (nhop->vrf_id != ifp->vrf->vrf_id) {
other_nh_count++;
continue;
}
nhop_found = true;
}
if (!nhop_found && !nhop_ll_found)
/* The event interface does not match the nexthop cache
* entry */
continue;
if (!up && other_nh_count > 0)
/* Down event ignored in case of multiple next-hop
* interfaces. The other might interfaces might be still
* up. The cases where all interfaces are down or a bnc
* is invalid are processed by a separate zebra rnh
* messages.
*/
continue;
if (!nhop_ll_found) {
evaluate_paths(bnc);
continue;
}
bnc->last_update = monotime(NULL);
bnc->change_flags = 0;
@ -822,7 +785,6 @@ static void bgp_nht_ifp_table_handle(struct bgp *bgp,
if (up) {
SET_FLAG(bnc->flags, BGP_NEXTHOP_VALID);
SET_FLAG(bnc->change_flags, BGP_NEXTHOP_CHANGED);
/* change nexthop number only for ll */
bnc->nexthop_num = 1;
} else {
UNSET_FLAG(bnc->flags, BGP_NEXTHOP_PEER_NOTIFIED);