Hi Lucas! I tried to fix the same situation, but when learning happens through multiple transit switches. I thought it would be right hashing ICDB route UUID - In essence, its matching routes from ICDB to routes in NBDB directly. This approach also fix situation you described, but with your patch, ICDB will have two routes, but only one will be learned by the router. With mine, router will have two identical routes, which is generally questionable. In either case, network won't work because packets will flapping between availability zones when processed on the transit switch, so I don't have any strong arguments for whether this is a good or bad thing. In SBDB on the router, even with two routes, we'll only see one logical flow because routes are literally identical. One small argument: it seems it will be easier for the user to see that the situation as such is not valid if he sees two routes instead of one. Here's the patch I made - https://github.com/Sashhkaa/ovn/commit/74c6a322a7505c0a13efdb20f58b1f6018f3d016
What do you think? If you don't mind, I can send you this patch. And again, sorry if I interrupted your work on this. On 24.02.2026 15:16, Rukomoinikova Aleksandra wrote: > Hi Lucas! > >> Avoid learned route loop if two differents AZs >> configure the same address and adv ther same prefix. >> Do not remove the route from routes learned structure, >> mark the route as not stale. > nit: Maybe, it's worth clarifying that the patch solves the problem when such > learning happen through a single transit switch? > > In case where there are multiple transit switches, routes won't be > endlessly learned, but there will be a different problem with the > endless updating of external_ids, which will be updated with different > transit switch's TS. This problem is not related to the problem of > endless route learning in general, but it seems worth mentioning for > easier tracking later. > >> Signed-off-by: Lucas Vargas Dias <lucas.vdias at luizalabs.com >> <https://mail.openvswitch.org/mailman/listinfo/ovs-dev>> >> --- >> ic/ovn-ic.c | 17 ++++++++------ >> tests/ovn-ic.at | 60 +++++++++++++++++++++++++++++++++++++++++++++++++ >> 2 files changed, 70 insertions(+), 7 deletions(-) >> >> diff --git a/ic/ovn-ic.c b/ic/ovn-ic.c >> index 95d73cb4b..3f3c0d99d 100644 >> --- a/ic/ovn-ic.c >> +++ b/ic/ovn-ic.c >> @@ -1300,6 +1300,7 @@ struct ic_route_info { >> const struct nbrec_logical_router_static_route *nb_route; >> const struct nbrec_logical_router_port *nb_lrp; >> const struct nbrec_load_balancer *nb_lb; >> + bool stale; /* True if the route is stale and should be removed. */ >> }; >> >> static uint32_t >> @@ -1393,6 +1394,7 @@ 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; >> + ic_route->stale = true; >> hmap_insert(routes_learned, &ic_route->node, >> ic_route_hash(&prefix, plen, &nexthop, origin, >> nb_route->route_table)); >> @@ -2168,8 +2170,7 @@ sync_learned_routes(struct ic_context *ctx, >> route_learned->nb_route, "ic-learned-route", >> uuid_s); >> free(uuid_s); >> } >> - hmap_remove(&ic_lr->routes_learned, &route_learned->node); >> - free(route_learned); >> + route_learned->stale = false; >> } else { >> /* Create the missing route in NB. */ >> const struct nbrec_logical_router_static_route *nb_route = >> @@ -2197,11 +2198,13 @@ sync_learned_routes(struct ic_context *ctx, >> /* Delete extra learned routes. */ >> struct ic_route_info *route_learned; >> HMAP_FOR_EACH_SAFE (route_learned, node, &ic_lr->routes_learned) { >> - VLOG_DBG("Delete route %s -> %s that is not in IC-SB from NB.", >> - route_learned->nb_route->ip_prefix, >> - route_learned->nb_route->nexthop); >> - nbrec_logical_router_update_static_routes_delvalue( >> - ic_lr->lr, route_learned->nb_route); >> + if (route_learned->stale) { >> + VLOG_DBG("Delete route %s -> %s that is not in IC-SB from NB.", >> + route_learned->nb_route->ip_prefix, >> + route_learned->nb_route->nexthop); >> + nbrec_logical_router_update_static_routes_delvalue( >> + ic_lr->lr, route_learned->nb_route); >> + } >> hmap_remove(&ic_lr->routes_learned, &route_learned->node); >> free(route_learned); >> } >> diff --git a/tests/ovn-ic.at b/tests/ovn-ic.at >> index 1a826aa1c..ead16aa91 100644 >> --- a/tests/ovn-ic.at >> +++ b/tests/ovn-ic.at >> @@ -3394,6 +3394,66 @@ OVN_CLEANUP_IC([az1], [az2]) >> AT_CLEANUP >> ]) >> >> +OVN_FOR_EACH_NORTHD([ >> +AT_SETUP([ovn-ic -- check loop with LSP of duplicated address]) >> + >> +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$i >> + >> + lr=lr1$i >> + check ovn-nbctl lr-add $lr >> + >> + check ovn-ic-nbctl --wait=sb --may-exist ts-add ts11 >> + >> + lrp=lrp-$lr-ts11 >> + lsp=lsp-ts11-$lr >> + # Create LRP and connect to TS >> + check ovn-nbctl lrp-add $lr $lrp aa:aa:aa:aa:a1:0$i 169.254.101.1/24 >> + check ovn-nbctl lsp-add-router-port ts11 $lsp $lrp >> +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" >> +sleep 2 > nit: It seems like a sleep is not needed here, bc line below calls WAIT macro > >> +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 >> +]) >> + >> +OVN_CLEANUP_IC([az1], [az2], [az3]) >> + >> +AT_CLEANUP >> +]) >> + >> OVN_FOR_EACH_NORTHD([ >> AT_SETUP([ovn-ic -- prefix filter -- filtering routes]) >> ovn_init_ic_db >> -- >> 2.43.0 > |Reviewed-by:| Alexandra Rukomoinikova <[email protected]> > -- regards, Alexandra. _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
