On Thu, Mar 5, 2026 at 6:44 PM Mark Michelson via dev <
[email protected]> wrote:

> Hi Alexandra, thanks for the patch!
>
> I have a couple of small notes below. They're so minor, that I think
> that a maintainer can fix them when merging, so there is no need for a
> v4.
>
> Acked-by: Mark Michelson <[email protected]>
>
> On Mon, Mar 2, 2026 at 7:35 AM Alexandra Rukomoinikova
> <[email protected]> wrote:
> >
> > The learned routes hash previously only used route parameters (prefix,
> > nexthop, origin, route_table). This caused collisions when identical
> > routes were learned through different transit switches, leading to
> > infinite route re-learning.
> >
> > While such configurations are invalid due to overlapping IP addressing
> > - ICshould handle them without looping.
> >
> > Fix by including the IC route UUID in the hash to distinguish routes
> > with identical parameters but different origins. As a result, routers
> > will now learn the correct number of prefixes as ECMP routes, making
> > the misconfiguration visible to the user.
> >
> > Signed-off-by: Alexandra Rukomoinikova <[email protected]>
> > ---
> > v1 --> v2: fixed typo in the tests
> > v2 --> v3: fixed hash calculation
> > ---
> >  ic/ovn-ic.c     | 56 ++++++++++++++--------------
> >  tests/ovn-ic.at | 98 +++++++++++++++++++++++++++++++++++++++++++++++++
> >  2 files changed, 127 insertions(+), 27 deletions(-)
> >
> > diff --git a/ic/ovn-ic.c b/ic/ovn-ic.c
> > index 95d73cb4b..7d2f9442a 100644
> > --- a/ic/ovn-ic.c
> > +++ b/ic/ovn-ic.c
> > @@ -1286,6 +1286,7 @@ struct ic_route_info {
> >      const char *origin;
> >      const char *route_table;
> >      const char *route_tag;
> > +    struct uuid ic_route_uuid;
> >
> >      const struct nbrec_logical_router *nb_lr;
> >
> > @@ -1305,9 +1306,11 @@ struct ic_route_info {
> >  static uint32_t
> >  ic_route_hash(const struct in6_addr *prefix, unsigned int plen,
> >                const struct in6_addr *nexthop, const char *origin,
> > -              const char *route_table)
> > +              const char *route_table, const struct uuid *ic_route_uuid)
> >  {
> > -    uint32_t basis = hash_bytes(prefix, sizeof *prefix, (uint32_t)plen);
> > +    uint32_t basis = ic_route_uuid ? uuid_hash(ic_route_uuid) : 0;
> > +    basis = hash_bytes(prefix, sizeof *prefix, basis);
> > +    basis = hash_int((uint32_t) plen, basis);
> >      basis = hash_string(origin, basis);
> >      basis = hash_string(route_table, basis);
> >      return hash_bytes(nexthop, sizeof *nexthop, basis);
> > @@ -1316,18 +1319,22 @@ ic_route_hash(const struct in6_addr *prefix,
> unsigned int plen,
> >  static struct ic_route_info *
> >  ic_route_find(struct hmap *routes, const struct in6_addr *prefix,
> >                unsigned int plen, const struct in6_addr *nexthop,
> > -              const char *origin, const char *route_table, uint32_t
> hash)
> > +              const char *origin, const char *route_table,
> > +              const struct uuid *ic_route_uuid, uint32_t hash)
> >  {
> >      struct ic_route_info *r;
> >      if (!hash) {
> > -        hash = ic_route_hash(prefix, plen, nexthop, origin,
> route_table);
> > +        hash = ic_route_hash(prefix, plen, nexthop, origin, route_table,
> > +                             ic_route_uuid);
> >      }
> >      HMAP_FOR_EACH_WITH_HASH (r, node, hash, routes) {
> >          if (ipv6_addr_equals(&r->prefix, prefix) &&
> >              r->plen == plen &&
> >              ipv6_addr_equals(&r->nexthop, nexthop) &&
> >              !strcmp(r->origin, origin) &&
> > -            !strcmp(r->route_table ? r->route_table : "", route_table))
> {
> > +            !strcmp(r->route_table ? r->route_table : "", route_table)
> &&
> > +            (!ic_route_uuid || uuid_equals(&r->ic_route_uuid,
> > +                                           ic_route_uuid))) {
> >              return r;
> >          }
> >      }
> > @@ -1370,7 +1377,8 @@ parse_route(const char *s_prefix, const char
> *s_nexthop,
> >  static bool
> >  add_to_routes_learned(struct hmap *routes_learned,
> >                        const struct nbrec_logical_router_static_route
> *nb_route,
> > -                      const struct nbrec_logical_router *nb_lr)
> > +                      const struct nbrec_logical_router *nb_lr,
> > +                      const struct uuid *ic_route_uuid)
> >  {
> >      struct in6_addr prefix, nexthop;
> >      unsigned int plen;
> > @@ -1379,8 +1387,11 @@ add_to_routes_learned(struct hmap *routes_learned,
> >          return false;
> >      }
> >      const char *origin = smap_get_def(&nb_route->options, "origin", "");
> > +
> > +    uint32_t hash = ic_route_hash(&prefix, plen, &nexthop, origin,
> > +                                  nb_route->route_table, ic_route_uuid);
> >      if (ic_route_find(routes_learned, &prefix, plen, &nexthop, origin,
> > -                      nb_route->route_table, 0)) {
> > +                      nb_route->route_table, ic_route_uuid, hash)) {
> >          /* Route was added to learned on previous iteration. */
> >          return true;
> >      }
> > @@ -1393,9 +1404,9 @@ add_to_routes_learned(struct hmap *routes_learned,
> >      ic_route->origin = origin;
> >      ic_route->route_table = nb_route->route_table;
> >      ic_route->nb_lr = nb_lr;
> > -    hmap_insert(routes_learned, &ic_route->node,
> > -                ic_route_hash(&prefix, plen, &nexthop, origin,
> > -                              nb_route->route_table));
> > +    memcpy(&ic_route->ic_route_uuid, ic_route_uuid, sizeof(struct
> uuid));
>
> There's no need for memcpy here. You can just do a struct assignment:
>
> ic_route->ic_route_uuid = *ic_route_uuid;
>
> > +    hmap_insert(routes_learned, &ic_route->node, hash);
> > +
> >      return true;
> >  }
> >
> > @@ -1562,10 +1573,11 @@ add_to_routes_ad(struct hmap *routes_ad, const
> struct in6_addr prefix,
> >          route_table = "";
> >      }
> >
> > -    uint hash = ic_route_hash(&prefix, plen, &nexthop, origin,
> route_table);
> > +    uint hash = ic_route_hash(&prefix, plen, &nexthop, origin,
> > +                              route_table, NULL);
> >
> >      if (!ic_route_find(routes_ad, &prefix, plen, &nexthop, origin,
> route_table,
> > -                       hash)) {
> > +                       NULL, hash)) {
> >          struct ic_route_info *ic_route = xzalloc(sizeof *ic_route);
> >          ic_route->prefix = prefix;
> >          ic_route->plen = plen;
> > @@ -2154,20 +2166,9 @@ sync_learned_routes(struct ic_context *ctx,
> >              struct ic_route_info *route_learned
> >                  = ic_route_find(&ic_lr->routes_learned, &prefix, plen,
> >                                  &nexthop, isb_route->origin,
> > -                                isb_route->route_table, 0);
> > +                                isb_route->route_table,
> > +                                &isb_route->header_.uuid, 0);
> >              if (route_learned) {
> > -                /* Sync external-ids */
> > -                struct uuid ext_id;
> > -                smap_get_uuid(&route_learned->nb_route->external_ids,
> > -                              "ic-learned-route", &ext_id);
> > -                if (!uuid_equals(&ext_id, &isb_route->header_.uuid)) {
> > -                    char *uuid_s =
> > -                        xasprintf(UUID_FMT,
> > -                                  UUID_ARGS(&isb_route->header_.uuid));
> > -
> nbrec_logical_router_static_route_update_external_ids_setkey(
> > -                        route_learned->nb_route, "ic-learned-route",
> uuid_s);
> > -                    free(uuid_s);
> > -                }
> >                  hmap_remove(&ic_lr->routes_learned,
> &route_learned->node);
> >                  free(route_learned);
> >              } else {
> > @@ -2275,7 +2276,7 @@ advertise_routes(struct ic_context *ctx,
> >          }
> >          struct ic_route_info *route_adv =
> >              ic_route_find(routes_ad, &prefix, plen, &nexthop,
> > -                          isb_route->origin, isb_route->route_table, 0);
> > +                          isb_route->origin, isb_route->route_table,
> NULL, 0);
> >          if (!route_adv) {
> >              /* Delete the extra route from IC-SB. */
> >              VLOG_DBG("Delete route %s -> %s from IC-SB, which is not
> found"
> > @@ -2349,7 +2350,8 @@ build_ts_routes_to_adv(struct ic_context *ctx,
> >          if (smap_get_uuid(&nb_route->external_ids, "ic-learned-route",
> >                            &isb_uuid)) {
> >              /* It is a learned route */
> > -            if (!add_to_routes_learned(&ic_lr->routes_learned,
> nb_route, lr)) {
> > +            if (!add_to_routes_learned(&ic_lr->routes_learned,
> nb_route, lr,
> > +                                       &isb_uuid)) {
> >                  static struct vlog_rate_limit rl =
> VLOG_RATE_LIMIT_INIT(5, 1);
> >                  VLOG_WARN_RL(&rl, "Bad format of learned route in NB: "
> >                               "%s -> %s. Delete it.",
> nb_route->ip_prefix,
> > diff --git a/tests/ovn-ic.at b/tests/ovn-ic.at
> > index 1a826aa1c..c633cdeb4 100644
> > --- a/tests/ovn-ic.at
> > +++ b/tests/ovn-ic.at
> > @@ -4594,3 +4594,101 @@ OVN_CLEANUP_IC([az1], [az2])
> >
> >  AT_CLEANUP
> >  ])
> > +
> > +OVN_FOR_EACH_NORTHD([
> > +AT_SETUP([ovn-ic -- check loop with annonce duplicated prefixes -
> multiple ts])
>
> s/annonce/announce/
>
> The same mistake happens a few other times in this test as well.
>
>
>
> > +
> > +ovn_init_ic_db
> > +ovn-ic-nbctl ts-add ts11
> > +ovn-ic-nbctl ts-add ts12
> > +
> > +for i in 1 2; do
> > +    ovn_start az$i
> > +    ovn_as az$i
> > +
> > +    # Enable route learning at AZ level
> > +    check ovn-nbctl set nb_global . options:ic-route-learn=true
> > +    # Enable route advertising at AZ level
> > +    check ovn-nbctl set nb_global . options:ic-route-adv=true
> > +done
> > +
> > +for i in 1 2; do
> > +    ovn_as az$i
> > +
> > +    check ovn-nbctl lr-add lr$i
> > +
> > +    check ovn-nbctl lrp-add lr$i lr-lrp-$i aa:aa:aa:aa:a1:0$i
> 169.254.101.1/24
> > +    check ovn-nbctl lsp-add-router-port ts11 lsp-az$i lr-lrp-$i
> > +
> > +    # Create subnet for annonce.
> > +    check ovn-nbctl lrp-add lr$i lr-lrp-subnet-$i aa:aa:aa:aa:a2:0$i
> 192.168.0.$i/24
> > +
> > +    # Create one more lrp-ts port through another transit switch.
> > +    check ovn-nbctl lrp-add lr$i lr-lrp-dup$i aa:aa:aa:aa:a3:01
> 169.254.101.1/24
> > +    check ovn-nbctl lsp-add-router-port ts12 lsp-dup-az$i lr-lrp-dup$i
> > +done
> > +
> > +OVS_WAIT_FOR_OUTPUT([ovn_as az1 ovn-nbctl lr-route-list lr1 | grep
> 192.168 |
> > +                     grep learned | awk '{print $1, $2}' | sort ], [0],
> [dnl
> > +192.168.0.0/24 169.254.101.1
> > +192.168.0.0/24 169.254.101.1
> > +])
> > +
> > +OVN_CLEANUP_IC([az1], [az2])
> > +AT_CLEANUP
> > +])
> > +
> > +OVN_FOR_EACH_NORTHD([
> > +AT_SETUP([ovn-ic -- check loop with annonce duplicated prefixes -
> single ts])
> > +
> > +ovn_init_ic_db
> > +
> > +for i in 1 2 3; do
> > +    ovn_start az$i
> > +    ovn_as az$i
> > +
> > +    # Enable route learning at AZ level
> > +    check ovn-nbctl set nb_global . options:ic-route-learn=true
> > +    # Enable route advertising at AZ level
> > +    check ovn-nbctl set nb_global . options:ic-route-adv=true
> > +done
> > +
> > +# Create new transit switches and LRs. Test topology is next:
> > +#                            logical router (lr12)
> > +#                                   |
> > +# logical router (lr11) -  / transit switch (ts11) \ - logical router
> (lr13)
> > +#
> > +
> > +# Create lr11, lr13, ts11 and connect them
> > +for i in 1 3; do
> > +    ovn_as az$i
> > +
> > +    check ovn-nbctl lr-add lr1$i
> > +    check ovn-ic-nbctl --wait=sb --may-exist ts-add ts11
> > +
> > +    # Create LRP and connect to TS
> > +    check ovn-nbctl lrp-add lr1$i lrp-lr1$i-ts11 aa:aa:aa:aa:a1:0$i
> 169.254.101.1/24
> > +    check ovn-nbctl lsp-add-router-port ts11 lsp-ts11-lr1$i
> lrp-lr1$i-ts11
> > +done
> > +
> > +# Create lr12 and connect it to ts11
> > +ovn_as az2
> > +check ovn-nbctl lr-add lr12
> > +
> > +# Create LRP and connect to TS
> > +check ovn-nbctl lrp-add lr12 lrp-lr12-ts11 aa:aa:aa:aa:a1:03
> 169.254.101.2/24
> > +check ovn-nbctl lsp-add-router-port ts11 lsp-lr12-ts11 lrp-lr12-ts11
> > +
> > +# Create directly-connected route in lr11
> > +check ovn_as az1 ovn-nbctl lrp-add lr11 lrp-lr11 aa:aa:aa:aa:bb:01 "
> 192.168.0.1/24"
> > +check ovn_as az3 ovn-nbctl lrp-add lr13 lrp-lr13 aa:aa:aa:aa:bb:03 "
> 192.168.0.1/24"
> > +
> > +OVS_WAIT_FOR_OUTPUT([ovn_as az2 ovn-nbctl lr-route-list lr12 | grep
> 192.168 |
> > +                     grep learned | awk '{print $1, $2}' | sort ], [0],
> [dnl
> > +192.168.0.0/24 169.254.101.1
> > +192.168.0.0/24 169.254.101.1
> > +])
> > +
> > +OVN_CLEANUP_IC([az1], [az2], [az3])
> > +AT_CLEANUP
> > +])
> > --
> > 2.48.1
> >
> > _______________________________________________
> > dev mailing list
> > [email protected]
> > https://mail.openvswitch.org/mailman/listinfo/ovs-dev
> >
>
> _______________________________________________
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Thank you Alexandra and Mark,

I'm slightly confused; the commit message says it's a fix, but there isn't
a Fixes tag. Also based on the commit message about invalid configuration I
don't think this needs a backport, please let me know if that's not the
case. I've fixed the nits and applied to main.

Regards,
Ales
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