diff --git a/include/ovn/logical-fields.h b/include/ovn/logical-fields.h
index dc3f3caf54..d6c4a9b6b3 100644
--- a/include/ovn/logical-fields.h
+++ b/include/ovn/logical-fields.h
@@ -197,13 +197,13 @@ const struct ovn_field *ovn_field_from_name(const char *name);
 #define OVN_CT_NATTED_BIT  1
 #define OVN_CT_LB_SKIP_SNAT_BIT 2
 #define OVN_CT_LB_FORCE_SNAT_BIT 3
-#define OVN_CT_OBS_AFTER_LB_BIT 4
+#define OVN_CT_OBS_STAGE_1ST_BIT 4
+#define OVN_CT_OBS_STAGE_END_BIT 5
 
 #define OVN_CT_BLOCKED 1
 #define OVN_CT_NATTED  2
 #define OVN_CT_LB_SKIP_SNAT 4
 #define OVN_CT_LB_FORCE_SNAT 8
-#define OVN_CT_OBS_AFTER_LB 16
 
 #define OVN_CT_ECMP_ETH_1ST_BIT 32
 #define OVN_CT_ECMP_ETH_END_BIT 79
diff --git a/lib/logical-fields.c b/lib/logical-fields.c
index 4e95aba4b3..134d2674fd 100644
--- a/lib/logical-fields.c
+++ b/lib/logical-fields.c
@@ -165,9 +165,10 @@ ovn_init_symtab(struct shash *symtab)
                                     OVN_CT_STR(OVN_CT_LB_FORCE_SNAT_BIT)
                                     "]",
                                     WR_CT_COMMIT);
-    expr_symtab_add_subfield_scoped(symtab, "ct_mark.obs_after_lb", NULL,
+    expr_symtab_add_subfield_scoped(symtab, "ct_mark.obs_stage", NULL,
                                     "ct_mark["
-                                    OVN_CT_STR(OVN_CT_OBS_AFTER_LB_BIT)
+                                    OVN_CT_STR(OVN_CT_OBS_STAGE_1ST_BIT) ".."
+                                    OVN_CT_STR(OVN_CT_OBS_STAGE_END_BIT)
                                     "]",
                                     WR_CT_COMMIT);
     expr_symtab_add_subfield_scoped(symtab, "ct_mark.obs_collector_id", NULL,
diff --git a/northd/northd.c b/northd/northd.c
index 6c41f52cc8..97bc54129c 100644
--- a/northd/northd.c
+++ b/northd/northd.c
@@ -144,8 +144,20 @@ static bool vxlan_mode;
 #define REGBIT_ACL_VERDICT_ALLOW "reg8[16]"
 #define REGBIT_ACL_VERDICT_DROP "reg8[17]"
 #define REGBIT_ACL_VERDICT_REJECT "reg8[18]"
+#define REGBIT_ACL_OBS_STAGE "reg8[19..20]"
 #define REG_ACL_TIER "reg8[30..31]"
 
+enum acl_observation_stage {
+    ACL_OBS_FROM_LPORT,
+    ACL_OBS_FROM_LPORT_AFTER_LB,
+    ACL_OBS_TO_LPORT,
+    ACL_OBS_STAGE_MAX
+};
+
+/* enum acl_observation_stage_t values must fit in the 2 bits of
+ * REGBIT_ACL_OBS_STAGE .*/
+BUILD_ASSERT_DECL(ACL_OBS_STAGE_MAX < (1 << 2));
+
 /* Indicate that this packet has been recirculated using egress
  * loopback.  This allows certain checks to be bypassed, such as a
  * logical router dropping packets with source IP address equals
@@ -191,7 +203,6 @@ static bool vxlan_mode;
 #define REG_OBS_POINT_ID_EST "reg9"
 #define REG_OBS_COLLECTOR_ID_NEW "reg8[0..7]"
 #define REG_OBS_COLLECTOR_ID_EST "reg2[16..23]"
-#define REGBIT_OBS_AFTER_LB "reg8[19]"
 
 /* Register used for temporarily store ECMP eth.src to avoid masked ct_label
  * access. It doesn't really occupy registers because the content of the
@@ -6525,7 +6536,7 @@ static void
 build_acl_sample_label_action(struct ds *actions, const struct nbrec_acl *acl,
                               const struct nbrec_sample *sample_new,
                               const struct nbrec_sample *sample_est,
-                              bool obs_after_lb)
+                              enum acl_observation_stage obs_stage)
 {
     if (!acl->label && !sample_new && !sample_est) {
         return;
@@ -6559,10 +6570,10 @@ build_acl_sample_label_action(struct ds *actions, const struct nbrec_acl *acl,
                            REG_OBS_POINT_ID_EST " = %"PRIu32"; "
                            REG_OBS_COLLECTOR_ID_NEW " = %"PRIu8"; "
                            REG_OBS_COLLECTOR_ID_EST " = %"PRIu8"; "
-                           REGBIT_OBS_AFTER_LB " = %c; ",
+                           REGBIT_ACL_OBS_STAGE " = %"PRIu8"; ",
                   point_id_new, point_id_est,
                   collector_id_new, collector_id_est,
-                  obs_after_lb ? '1' : '0');
+                  (uint8_t) obs_stage);
 }
 
 /* This builds an ACL logical flow specific match that selects traffic
@@ -6737,6 +6748,7 @@ static void
 build_acl_sample_generic_new_flows(const struct ovn_datapath *od,
                                    struct lflow_table *lflows,
                                    enum ovn_stage stage,
+                                   enum acl_observation_stage obs_stage,
                                    struct ds *match, struct ds *actions,
                                    const struct nbrec_sample_collector *coll,
                                    uint8_t sample_domain_id, bool stateful,
@@ -6746,10 +6758,10 @@ build_acl_sample_generic_new_flows(const struct ovn_datapath *od,
     ds_clear(actions);
 
     ds_put_format(match, "ip %s&& "REG_OBS_COLLECTOR_ID_NEW" == %"PRIu8" && "
-                         REGBIT_OBS_AFTER_LB" == %c",
+                         REGBIT_ACL_OBS_STAGE " == %"PRIu8,
                          stateful ? "&& ct.new " : "",
                          (uint8_t) coll->set_id,
-                         stage == S_SWITCH_IN_ACL_AFTER_LB_SAMPLE ? '1' : '0');
+                         (uint8_t) obs_stage);
 
     ds_put_format(actions, "sample(probability=%"PRIu16","
                            "collector_set=%"PRIu8","
@@ -6772,6 +6784,7 @@ static void
 build_acl_sample_generic_est_flows(const struct ovn_datapath *od,
                                    struct lflow_table *lflows,
                                    enum ovn_stage stage,
+                                   enum acl_observation_stage obs_stage,
                                    struct ds *match, struct ds *actions,
                                    const struct nbrec_sample_collector *coll,
                                    uint8_t sample_domain_id,
@@ -6785,9 +6798,9 @@ build_acl_sample_generic_est_flows(const struct ovn_datapath *od,
 
     size_t match_len = match->length;
     ds_put_format(match, "!ct.rpl && ct_mark.obs_collector_id == %"PRIu8" && "
-                         "ct_mark.obs_after_lb == %c",
+                         "ct_mark.obs_stage == %"PRIu8,
                          (uint8_t) coll->set_id,
-                         stage == S_SWITCH_IN_ACL_AFTER_LB_SAMPLE ? '1' : '0');
+                         (uint8_t) obs_stage);
 
     ds_put_format(actions, "sample(probability=%"PRIu16","
                            "collector_set=%"PRIu8","
@@ -6857,13 +6870,17 @@ build_acl_sample_flows(const struct ls_stateful_record *ls_stateful_rec,
 
     bool ingress = !strcmp(acl->direction, "from-lport") ? true : false;
     enum ovn_stage stage;
+    enum acl_observation_stage obs_stage;
 
     if (ingress && smap_get_bool(&acl->options, "apply-after-lb", false)) {
         stage = S_SWITCH_IN_ACL_AFTER_LB_SAMPLE;
+        obs_stage = ACL_OBS_FROM_LPORT_AFTER_LB;
     } else if (ingress) {
         stage = S_SWITCH_IN_ACL_SAMPLE;
+        obs_stage = ACL_OBS_FROM_LPORT;
     } else {
         stage = S_SWITCH_OUT_ACL_SAMPLE;
+        obs_stage = ACL_OBS_TO_LPORT;
     }
 
     uint8_t sample_new_domain_id =
@@ -6872,7 +6889,8 @@ build_acl_sample_flows(const struct ls_stateful_record *ls_stateful_rec,
         sampling_app_get_id(sampling_apps, SAMPLING_APP_ACL_EST_TRAFFIC);
 
     if (acl_use_generic_sample_flows(acl->sample_new, features)) {
-        build_acl_sample_generic_new_flows(od, lflows, stage, match, actions,
+        build_acl_sample_generic_new_flows(od, lflows, stage, obs_stage,
+                                           match, actions,
                                            acl->sample_new->collectors[0],
                                            sample_new_domain_id,
                                            stateful_match, lflow_ref);
@@ -6887,7 +6905,8 @@ build_acl_sample_flows(const struct ls_stateful_record *ls_stateful_rec,
     }
 
     if (acl_use_generic_sample_flows(acl->sample_est, features)) {
-        build_acl_sample_generic_est_flows(od, lflows, stage, match, actions,
+        build_acl_sample_generic_est_flows(od, lflows, stage, obs_stage,
+                                           match, actions,
                                            acl->sample_est->collectors[0],
                                            sample_est_domain_id, lflow_ref);
     } else {
@@ -6922,15 +6941,17 @@ consider_acl(struct lflow_table *lflows, const struct ovn_datapath *od,
 {
     bool ingress = !strcmp(acl->direction, "from-lport") ? true :false;
     enum ovn_stage stage;
+    enum acl_observation_stage obs_stage;
 
-    bool apply_after_lb = false;
     if (ingress && smap_get_bool(&acl->options, "apply-after-lb", false)) {
         stage = S_SWITCH_IN_ACL_AFTER_LB_EVAL;
-        apply_after_lb = true;
+        obs_stage = ACL_OBS_FROM_LPORT_AFTER_LB;
     } else if (ingress) {
         stage = S_SWITCH_IN_ACL_EVAL;
+        obs_stage = ACL_OBS_FROM_LPORT;
     } else {
         stage = S_SWITCH_OUT_ACL_EVAL;
+        obs_stage = ACL_OBS_TO_LPORT;
     }
 
     const char *verdict;
@@ -6965,7 +6986,7 @@ consider_acl(struct lflow_table *lflows, const struct ovn_datapath *od,
 
         /* For stateless ACLs just sample "new" packets. */
         build_acl_sample_label_action(actions, acl, acl->sample_new, NULL,
-                                      apply_after_lb);
+                                      obs_stage);
 
         ds_put_cstr(actions, "next;");
         ds_put_format(match, "(%s)", acl->match);
@@ -7004,7 +7025,7 @@ consider_acl(struct lflow_table *lflows, const struct ovn_datapath *od,
 
         /* For stateful ACLs sample "new" and "established" packets. */
         build_acl_sample_label_action(actions, acl, acl->sample_new,
-                                      acl->sample_est, apply_after_lb);
+                                      acl->sample_est, obs_stage);
         ds_put_cstr(actions, "next;");
         ovn_lflow_add_with_hint(lflows, od, stage, priority,
                                 ds_cstr(match), ds_cstr(actions),
@@ -7028,7 +7049,7 @@ consider_acl(struct lflow_table *lflows, const struct ovn_datapath *od,
 
         /* For stateful ACLs sample "new" and "established" packets. */
         build_acl_sample_label_action(actions, acl, acl->sample_new,
-                                      acl->sample_est, apply_after_lb);
+                                      acl->sample_est, obs_stage);
         ds_put_cstr(actions, "next;");
         ovn_lflow_add_with_hint(lflows, od, stage, priority,
                                 ds_cstr(match), ds_cstr(actions),
@@ -7049,7 +7070,7 @@ consider_acl(struct lflow_table *lflows, const struct ovn_datapath *od,
 
         /* For drop ACLs just sample all packets as "new" packets. */
         build_acl_sample_label_action(actions, acl, acl->sample_new, NULL,
-                                      apply_after_lb);
+                                      obs_stage);
         ds_put_cstr(actions, "next;");
         ovn_lflow_add_with_hint(lflows, od, stage, priority,
                                 ds_cstr(match), ds_cstr(actions),
@@ -7073,7 +7094,7 @@ consider_acl(struct lflow_table *lflows, const struct ovn_datapath *od,
 
         /* For drop ACLs just sample all packets as "new" packets. */
         build_acl_sample_label_action(actions, acl, acl->sample_new, NULL,
-                                      apply_after_lb);
+                                      obs_stage);
         ds_put_cstr(actions, "ct_commit { ct_mark.blocked = 1; }; next;");
         ovn_lflow_add_with_hint(lflows, od, stage, priority,
                                 ds_cstr(match), ds_cstr(actions),
@@ -8195,7 +8216,7 @@ build_stateful(struct ovn_datapath *od, struct lflow_table *lflows,
     ds_put_cstr(&actions,
                  "ct_commit { "
                     "ct_mark.blocked = 0; "
-                    "ct_mark.obs_after_lb = " REGBIT_OBS_AFTER_LB "; "
+                    "ct_mark.obs_stage = " REGBIT_ACL_OBS_STAGE "; "
                     "ct_mark.obs_collector_id = " REG_OBS_COLLECTOR_ID_EST "; "
                     "ct_label.obs_point_id = " REG_OBS_POINT_ID_EST "; "
                   "}; next;");
diff --git a/tests/ovn-northd.at b/tests/ovn-northd.at
index c8a16d1892..f4adff1a81 100644
--- a/tests/ovn-northd.at
+++ b/tests/ovn-northd.at
@@ -4608,7 +4608,7 @@ check_stateful_flows() {
     AT_CHECK([grep "ls_in_stateful" sw0flows | ovn_strip_lflows], [0], [dnl
   table=??(ls_in_stateful     ), priority=0    , match=(1), action=(next;)
   table=??(ls_in_stateful     ), priority=100  , match=(reg0[[1]] == 1 && reg0[[13]] == 0), action=(ct_commit { ct_mark.blocked = 0; }; next;)
-  table=??(ls_in_stateful     ), priority=100  , match=(reg0[[1]] == 1 && reg0[[13]] == 1), action=(ct_commit { ct_mark.blocked = 0; ct_mark.obs_after_lb = reg8[[19]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; }; next;)
+  table=??(ls_in_stateful     ), priority=100  , match=(reg0[[1]] == 1 && reg0[[13]] == 1), action=(ct_commit { ct_mark.blocked = 0; ct_mark.obs_stage = reg8[[19..20]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; }; next;)
 ])
 
     AT_CHECK_UNQUOTED([grep "ls_out_pre_lb" sw0flows | ovn_strip_lflows], [0], [dnl
@@ -4632,7 +4632,7 @@ check_stateful_flows() {
     AT_CHECK([grep "ls_out_stateful" sw0flows | ovn_strip_lflows], [0], [dnl
   table=??(ls_out_stateful    ), priority=0    , match=(1), action=(next;)
   table=??(ls_out_stateful    ), priority=100  , match=(reg0[[1]] == 1 && reg0[[13]] == 0), action=(ct_commit { ct_mark.blocked = 0; }; next;)
-  table=??(ls_out_stateful    ), priority=100  , match=(reg0[[1]] == 1 && reg0[[13]] == 1), action=(ct_commit { ct_mark.blocked = 0; ct_mark.obs_after_lb = reg8[[19]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; }; next;)
+  table=??(ls_out_stateful    ), priority=100  , match=(reg0[[1]] == 1 && reg0[[13]] == 1), action=(ct_commit { ct_mark.blocked = 0; ct_mark.obs_stage = reg8[[19..20]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; }; next;)
 ])
 }
 
@@ -4674,7 +4674,7 @@ AT_CHECK([grep "ls_in_lb " sw0flows | ovn_strip_lflows], [0], [dnl
 AT_CHECK([grep "ls_in_stateful" sw0flows | ovn_strip_lflows], [0], [dnl
   table=??(ls_in_stateful     ), priority=0    , match=(1), action=(next;)
   table=??(ls_in_stateful     ), priority=100  , match=(reg0[[1]] == 1 && reg0[[13]] == 0), action=(ct_commit { ct_mark.blocked = 0; }; next;)
-  table=??(ls_in_stateful     ), priority=100  , match=(reg0[[1]] == 1 && reg0[[13]] == 1), action=(ct_commit { ct_mark.blocked = 0; ct_mark.obs_after_lb = reg8[[19]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; }; next;)
+  table=??(ls_in_stateful     ), priority=100  , match=(reg0[[1]] == 1 && reg0[[13]] == 1), action=(ct_commit { ct_mark.blocked = 0; ct_mark.obs_stage = reg8[[19..20]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; }; next;)
 ])
 
 AT_CHECK([grep "ls_out_pre_lb" sw0flows | ovn_strip_lflows], [0], [dnl
@@ -4695,7 +4695,7 @@ AT_CHECK([grep "ls_out_pre_stateful" sw0flows | ovn_strip_lflows], [0], [dnl
 AT_CHECK([grep "ls_out_stateful" sw0flows | ovn_strip_lflows], [0], [dnl
   table=??(ls_out_stateful    ), priority=0    , match=(1), action=(next;)
   table=??(ls_out_stateful    ), priority=100  , match=(reg0[[1]] == 1 && reg0[[13]] == 0), action=(ct_commit { ct_mark.blocked = 0; }; next;)
-  table=??(ls_out_stateful    ), priority=100  , match=(reg0[[1]] == 1 && reg0[[13]] == 1), action=(ct_commit { ct_mark.blocked = 0; ct_mark.obs_after_lb = reg8[[19]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; }; next;)
+  table=??(ls_out_stateful    ), priority=100  , match=(reg0[[1]] == 1 && reg0[[13]] == 1), action=(ct_commit { ct_mark.blocked = 0; ct_mark.obs_stage = reg8[[19..20]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; }; next;)
 ])
 
 # LB with event=false and reject=false
@@ -4724,23 +4724,23 @@ ovn-sbctl dump-flows sw0 > sw0flows
 AT_CAPTURE_FILE([sw0flows])
 
 AT_CHECK([grep -w "ls_in_acl_eval" sw0flows | grep 2002 | ovn_strip_lflows], [0], [dnl
-  table=??(ls_in_acl_eval     ), priority=2002 , match=(reg0[[7]] == 1 && (tcp)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 1234; reg9 = 1234; reg8[[0..7]] = 0; reg2[[16..23]] = 0; reg8[[19]] = 0; next;)
-  table=??(ls_in_acl_eval     ), priority=2002 , match=(reg0[[8]] == 1 && (tcp)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 1234; reg9 = 1234; reg8[[0..7]] = 0; reg2[[16..23]] = 0; reg8[[19]] = 0; next;)
+  table=??(ls_in_acl_eval     ), priority=2002 , match=(reg0[[7]] == 1 && (tcp)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 1234; reg9 = 1234; reg8[[0..7]] = 0; reg2[[16..23]] = 0; reg8[[19..20]] = 0; next;)
+  table=??(ls_in_acl_eval     ), priority=2002 , match=(reg0[[8]] == 1 && (tcp)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 1234; reg9 = 1234; reg8[[0..7]] = 0; reg2[[16..23]] = 0; reg8[[19..20]] = 0; next;)
 ])
 AT_CHECK([grep "ls_in_stateful" sw0flows | ovn_strip_lflows], [0], [dnl
   table=??(ls_in_stateful     ), priority=0    , match=(1), action=(next;)
   table=??(ls_in_stateful     ), priority=100  , match=(reg0[[1]] == 1 && reg0[[13]] == 0), action=(ct_commit { ct_mark.blocked = 0; }; next;)
-  table=??(ls_in_stateful     ), priority=100  , match=(reg0[[1]] == 1 && reg0[[13]] == 1), action=(ct_commit { ct_mark.blocked = 0; ct_mark.obs_after_lb = reg8[[19]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; }; next;)
+  table=??(ls_in_stateful     ), priority=100  , match=(reg0[[1]] == 1 && reg0[[13]] == 1), action=(ct_commit { ct_mark.blocked = 0; ct_mark.obs_stage = reg8[[19..20]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; }; next;)
 ])
 
 AT_CHECK([grep -w "ls_out_acl_eval" sw0flows | grep 2002 | ovn_strip_lflows], [0], [dnl
-  table=??(ls_out_acl_eval    ), priority=2002 , match=(reg0[[7]] == 1 && (tcp)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 1234; reg9 = 1234; reg8[[0..7]] = 0; reg2[[16..23]] = 0; reg8[[19]] = 0; next;)
-  table=??(ls_out_acl_eval    ), priority=2002 , match=(reg0[[8]] == 1 && (tcp)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 1234; reg9 = 1234; reg8[[0..7]] = 0; reg2[[16..23]] = 0; reg8[[19]] = 0; next;)
+  table=??(ls_out_acl_eval    ), priority=2002 , match=(reg0[[7]] == 1 && (tcp)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 1234; reg9 = 1234; reg8[[0..7]] = 0; reg2[[16..23]] = 0; reg8[[19..20]] = 2; next;)
+  table=??(ls_out_acl_eval    ), priority=2002 , match=(reg0[[8]] == 1 && (tcp)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 1234; reg9 = 1234; reg8[[0..7]] = 0; reg2[[16..23]] = 0; reg8[[19..20]] = 2; next;)
 ])
 AT_CHECK([grep "ls_out_stateful" sw0flows | ovn_strip_lflows], [0], [dnl
   table=??(ls_out_stateful    ), priority=0    , match=(1), action=(next;)
   table=??(ls_out_stateful    ), priority=100  , match=(reg0[[1]] == 1 && reg0[[13]] == 0), action=(ct_commit { ct_mark.blocked = 0; }; next;)
-  table=??(ls_out_stateful    ), priority=100  , match=(reg0[[1]] == 1 && reg0[[13]] == 1), action=(ct_commit { ct_mark.blocked = 0; ct_mark.obs_after_lb = reg8[[19]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; }; next;)
+  table=??(ls_out_stateful    ), priority=100  , match=(reg0[[1]] == 1 && reg0[[13]] == 1), action=(ct_commit { ct_mark.blocked = 0; ct_mark.obs_stage = reg8[[19..20]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; }; next;)
 ])
 
 # Add new ACL without label
@@ -4751,27 +4751,27 @@ ovn-sbctl dump-flows sw0 > sw0flows
 AT_CAPTURE_FILE([sw0flows])
 
 AT_CHECK([grep -w "ls_in_acl_eval" sw0flows | grep 2002 | ovn_strip_lflows], [0], [dnl
-  table=??(ls_in_acl_eval     ), priority=2002 , match=(reg0[[7]] == 1 && (tcp)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 1234; reg9 = 1234; reg8[[0..7]] = 0; reg2[[16..23]] = 0; reg8[[19]] = 0; next;)
+  table=??(ls_in_acl_eval     ), priority=2002 , match=(reg0[[7]] == 1 && (tcp)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 1234; reg9 = 1234; reg8[[0..7]] = 0; reg2[[16..23]] = 0; reg8[[19..20]] = 0; next;)
   table=??(ls_in_acl_eval     ), priority=2002 , match=(reg0[[7]] == 1 && (udp)), action=(reg8[[16]] = 1; reg0[[1]] = 1; next;)
-  table=??(ls_in_acl_eval     ), priority=2002 , match=(reg0[[8]] == 1 && (tcp)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 1234; reg9 = 1234; reg8[[0..7]] = 0; reg2[[16..23]] = 0; reg8[[19]] = 0; next;)
+  table=??(ls_in_acl_eval     ), priority=2002 , match=(reg0[[8]] == 1 && (tcp)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 1234; reg9 = 1234; reg8[[0..7]] = 0; reg2[[16..23]] = 0; reg8[[19..20]] = 0; next;)
   table=??(ls_in_acl_eval     ), priority=2002 , match=(reg0[[8]] == 1 && (udp)), action=(reg8[[16]] = 1; next;)
 ])
 AT_CHECK([grep "ls_in_stateful" sw0flows | ovn_strip_lflows], [0], [dnl
   table=??(ls_in_stateful     ), priority=0    , match=(1), action=(next;)
   table=??(ls_in_stateful     ), priority=100  , match=(reg0[[1]] == 1 && reg0[[13]] == 0), action=(ct_commit { ct_mark.blocked = 0; }; next;)
-  table=??(ls_in_stateful     ), priority=100  , match=(reg0[[1]] == 1 && reg0[[13]] == 1), action=(ct_commit { ct_mark.blocked = 0; ct_mark.obs_after_lb = reg8[[19]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; }; next;)
+  table=??(ls_in_stateful     ), priority=100  , match=(reg0[[1]] == 1 && reg0[[13]] == 1), action=(ct_commit { ct_mark.blocked = 0; ct_mark.obs_stage = reg8[[19..20]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; }; next;)
 ])
 
 AT_CHECK([grep -w "ls_out_acl_eval" sw0flows | grep 2002 | ovn_strip_lflows], [0], [dnl
-  table=??(ls_out_acl_eval    ), priority=2002 , match=(reg0[[7]] == 1 && (tcp)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 1234; reg9 = 1234; reg8[[0..7]] = 0; reg2[[16..23]] = 0; reg8[[19]] = 0; next;)
+  table=??(ls_out_acl_eval    ), priority=2002 , match=(reg0[[7]] == 1 && (tcp)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 1234; reg9 = 1234; reg8[[0..7]] = 0; reg2[[16..23]] = 0; reg8[[19..20]] = 2; next;)
   table=??(ls_out_acl_eval    ), priority=2002 , match=(reg0[[7]] == 1 && (udp)), action=(reg8[[16]] = 1; reg0[[1]] = 1; next;)
-  table=??(ls_out_acl_eval    ), priority=2002 , match=(reg0[[8]] == 1 && (tcp)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 1234; reg9 = 1234; reg8[[0..7]] = 0; reg2[[16..23]] = 0; reg8[[19]] = 0; next;)
+  table=??(ls_out_acl_eval    ), priority=2002 , match=(reg0[[8]] == 1 && (tcp)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 1234; reg9 = 1234; reg8[[0..7]] = 0; reg2[[16..23]] = 0; reg8[[19..20]] = 2; next;)
   table=??(ls_out_acl_eval    ), priority=2002 , match=(reg0[[8]] == 1 && (udp)), action=(reg8[[16]] = 1; next;)
 ])
 AT_CHECK([grep "ls_out_stateful" sw0flows | ovn_strip_lflows], [0], [dnl
   table=??(ls_out_stateful    ), priority=0    , match=(1), action=(next;)
   table=??(ls_out_stateful    ), priority=100  , match=(reg0[[1]] == 1 && reg0[[13]] == 0), action=(ct_commit { ct_mark.blocked = 0; }; next;)
-  table=??(ls_out_stateful    ), priority=100  , match=(reg0[[1]] == 1 && reg0[[13]] == 1), action=(ct_commit { ct_mark.blocked = 0; ct_mark.obs_after_lb = reg8[[19]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; }; next;)
+  table=??(ls_out_stateful    ), priority=100  , match=(reg0[[1]] == 1 && reg0[[13]] == 1), action=(ct_commit { ct_mark.blocked = 0; ct_mark.obs_stage = reg8[[19..20]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; }; next;)
 ])
 
 # Delete new ACL with label
@@ -4788,7 +4788,7 @@ AT_CHECK([grep -w "ls_in_acl_eval" sw0flows | grep 2002 | ovn_strip_lflows], [0]
 AT_CHECK([grep "ls_in_stateful" sw0flows | ovn_strip_lflows], [0], [dnl
   table=??(ls_in_stateful     ), priority=0    , match=(1), action=(next;)
   table=??(ls_in_stateful     ), priority=100  , match=(reg0[[1]] == 1 && reg0[[13]] == 0), action=(ct_commit { ct_mark.blocked = 0; }; next;)
-  table=??(ls_in_stateful     ), priority=100  , match=(reg0[[1]] == 1 && reg0[[13]] == 1), action=(ct_commit { ct_mark.blocked = 0; ct_mark.obs_after_lb = reg8[[19]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; }; next;)
+  table=??(ls_in_stateful     ), priority=100  , match=(reg0[[1]] == 1 && reg0[[13]] == 1), action=(ct_commit { ct_mark.blocked = 0; ct_mark.obs_stage = reg8[[19..20]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; }; next;)
 ])
 
 AT_CHECK([grep -w "ls_out_acl_eval" sw0flows | grep 2002 | ovn_strip_lflows], [0], [dnl
@@ -4798,7 +4798,7 @@ AT_CHECK([grep -w "ls_out_acl_eval" sw0flows | grep 2002 | ovn_strip_lflows], [0
 AT_CHECK([grep "ls_out_stateful" sw0flows | ovn_strip_lflows], [0], [dnl
   table=??(ls_out_stateful    ), priority=0    , match=(1), action=(next;)
   table=??(ls_out_stateful    ), priority=100  , match=(reg0[[1]] == 1 && reg0[[13]] == 0), action=(ct_commit { ct_mark.blocked = 0; }; next;)
-  table=??(ls_out_stateful    ), priority=100  , match=(reg0[[1]] == 1 && reg0[[13]] == 1), action=(ct_commit { ct_mark.blocked = 0; ct_mark.obs_after_lb = reg8[[19]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; }; next;)
+  table=??(ls_out_stateful    ), priority=100  , match=(reg0[[1]] == 1 && reg0[[13]] == 1), action=(ct_commit { ct_mark.blocked = 0; ct_mark.obs_stage = reg8[[19..20]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; }; next;)
 ])
 AT_CLEANUP
 ])
@@ -4826,7 +4826,7 @@ check ovn-nbctl --wait=sb -- acl-del ls -- --label=1234 acl-add ls from-lport 1
 
 dnl Check that the label is committed to conntrack in the ingress pipeline
 AT_CHECK_UNQUOTED([ovn_trace --ct new --ct new --ct new ls "$flow" | grep -e ls_in_stateful -A 2 | grep commit], [0], [dnl
-    ct_commit { ct_mark.blocked = 0; ct_mark.obs_after_lb = reg8[[19]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; };
+    ct_commit { ct_mark.blocked = 0; ct_mark.obs_stage = reg8[[19..20]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; };
 ])
 
 AS_BOX([from-lport --apply-after-lb allow-related ACL])
@@ -4834,7 +4834,7 @@ check ovn-nbctl --wait=sb -- acl-del ls -- --apply-after-lb --label=1234 acl-add
 
 dnl Check that the label is committed to conntrack in the ingress pipeline
 AT_CHECK_UNQUOTED([ovn_trace --ct new --ct new --ct new ls "$flow" | grep -e ls_in_stateful -A 2 | grep commit], [0], [dnl
-    ct_commit { ct_mark.blocked = 0; ct_mark.obs_after_lb = reg8[[19]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; };
+    ct_commit { ct_mark.blocked = 0; ct_mark.obs_stage = reg8[[19..20]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; };
 ])
 
 AS_BOX([to-lport allow-related ACL])
@@ -4842,7 +4842,7 @@ check ovn-nbctl --wait=sb -- acl-del ls -- --label=1234 acl-add ls to-lport 1 ip
 
 dnl Check that the label is committed to conntrack in the ingress pipeline
 AT_CHECK_UNQUOTED([ovn_trace --ct new --ct new --ct new ls "$flow" | grep -e ls_out_stateful -A 2 | grep commit], [0], [dnl
-    ct_commit { ct_mark.blocked = 0; ct_mark.obs_after_lb = reg8[[19]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; };
+    ct_commit { ct_mark.blocked = 0; ct_mark.obs_stage = reg8[[19..20]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; };
 ])
 
 AT_CLEANUP
@@ -7678,7 +7678,7 @@ AT_CHECK([grep -e "ls_in_lb " lsflows | ovn_strip_lflows], [0], [dnl
 AT_CHECK([grep -e "ls_in_stateful" lsflows | ovn_strip_lflows], [0], [dnl
   table=??(ls_in_stateful     ), priority=0    , match=(1), action=(next;)
   table=??(ls_in_stateful     ), priority=100  , match=(reg0[[1]] == 1 && reg0[[13]] == 0), action=(ct_commit { ct_mark.blocked = 0; }; next;)
-  table=??(ls_in_stateful     ), priority=100  , match=(reg0[[1]] == 1 && reg0[[13]] == 1), action=(ct_commit { ct_mark.blocked = 0; ct_mark.obs_after_lb = reg8[[19]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; }; next;)
+  table=??(ls_in_stateful     ), priority=100  , match=(reg0[[1]] == 1 && reg0[[13]] == 1), action=(ct_commit { ct_mark.blocked = 0; ct_mark.obs_stage = reg8[[19..20]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; }; next;)
 ])
 
 AS_BOX([Remove and add the ACLs back with the apply-after-lb option])
@@ -7733,7 +7733,7 @@ AT_CHECK([grep -e "ls_in_lb " lsflows | ovn_strip_lflows], [0], [dnl
 AT_CHECK([grep -e "ls_in_stateful" lsflows | ovn_strip_lflows], [0], [dnl
   table=??(ls_in_stateful     ), priority=0    , match=(1), action=(next;)
   table=??(ls_in_stateful     ), priority=100  , match=(reg0[[1]] == 1 && reg0[[13]] == 0), action=(ct_commit { ct_mark.blocked = 0; }; next;)
-  table=??(ls_in_stateful     ), priority=100  , match=(reg0[[1]] == 1 && reg0[[13]] == 1), action=(ct_commit { ct_mark.blocked = 0; ct_mark.obs_after_lb = reg8[[19]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; }; next;)
+  table=??(ls_in_stateful     ), priority=100  , match=(reg0[[1]] == 1 && reg0[[13]] == 1), action=(ct_commit { ct_mark.blocked = 0; ct_mark.obs_stage = reg8[[19..20]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; }; next;)
 ])
 
 AS_BOX([Remove and add the ACLs back with a few ACLs with apply-after-lb option])
@@ -7788,7 +7788,7 @@ AT_CHECK([grep -e "ls_in_lb " lsflows | ovn_strip_lflows], [0], [dnl
 AT_CHECK([grep -e "ls_in_stateful" lsflows | ovn_strip_lflows], [0], [dnl
   table=??(ls_in_stateful     ), priority=0    , match=(1), action=(next;)
   table=??(ls_in_stateful     ), priority=100  , match=(reg0[[1]] == 1 && reg0[[13]] == 0), action=(ct_commit { ct_mark.blocked = 0; }; next;)
-  table=??(ls_in_stateful     ), priority=100  , match=(reg0[[1]] == 1 && reg0[[13]] == 1), action=(ct_commit { ct_mark.blocked = 0; ct_mark.obs_after_lb = reg8[[19]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; }; next;)
+  table=??(ls_in_stateful     ), priority=100  , match=(reg0[[1]] == 1 && reg0[[13]] == 1), action=(ct_commit { ct_mark.blocked = 0; ct_mark.obs_stage = reg8[[19..20]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; }; next;)
 ])
 
 AT_CLEANUP
@@ -12599,8 +12599,8 @@ AS_BOX([from-lport ACL sampling (new, est)])
 check ovn-nbctl acl-del ls
 check ovn-nbctl --wait=sb --sample-new=$sample1 --sample-est=$sample2 acl-add ls from-lport 1 "1" allow-related
 AT_CHECK([ovn-sbctl lflow-list | grep -e ls_in_acl_sample -e ls_in_acl_eval -e ls_out_acl_sample | ovn_strip_lflows | ovn_strip_collector_set | grep -e reg3 -e reg9 -e sample], [0], [dnl
-  table=??(ls_in_acl_eval     ), priority=1001 , match=(reg0[[7]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 4302; reg8[[0..7]] = 0; reg2[[16..23]] = 0; reg8[[19]] = 0; next;)
-  table=??(ls_in_acl_eval     ), priority=1001 , match=(reg0[[8]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 4302; reg8[[0..7]] = 0; reg2[[16..23]] = 0; reg8[[19]] = 0; next;)
+  table=??(ls_in_acl_eval     ), priority=1001 , match=(reg0[[7]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 4302; reg8[[0..7]] = 0; reg2[[16..23]] = 0; reg8[[19..20]] = 0; next;)
+  table=??(ls_in_acl_eval     ), priority=1001 , match=(reg0[[8]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 4302; reg8[[0..7]] = 0; reg2[[16..23]] = 0; reg8[[19..20]] = 0; next;)
   table=??(ls_in_acl_sample   ), priority=0    , match=(1), action=(next;)
   table=??(ls_in_acl_sample   ), priority=1100 , match=(ip && ct.new && reg3 == 4301), action=(sample(probability=65535,collector_set=??,obs_domain=42,obs_point=4301);sample(probability=65535,collector_set=??,obs_domain=42,obs_point=4301); next;)
   table=??(ls_in_acl_sample   ), priority=1200 , match=(ip && ct.trk && (ct.est || ct.rel) && !ct.rpl && ct_label.obs_point_id == 4302 && ct_label.obs_unused == 0), action=(sample(probability=65535,collector_set=??,obs_domain=43,obs_point=4302);sample(probability=65535,collector_set=??,obs_domain=43,obs_point=4302); next;)
@@ -12611,7 +12611,7 @@ AT_CHECK([ovn-sbctl lflow-list | grep -e ls_in_acl_sample -e ls_in_acl_eval -e l
 dnl Trace new connections.
 flow="$base_flow"
 AT_CHECK_UNQUOTED([ovn_trace --ct new ls "$flow" | TRACE_FILTER], [0], [dnl
-    ct_commit { ct_mark.blocked = 0; ct_mark.obs_after_lb = reg8[[19]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; };
+    ct_commit { ct_mark.blocked = 0; ct_mark.obs_stage = reg8[[19..20]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; };
     reg9 = 4302;
     sample(probability=65535,collector_set=1,obs_domain=42,obs_point=4301);
     sample(probability=65535,collector_set=2,obs_domain=42,obs_point=4301);
@@ -12629,8 +12629,8 @@ AS_BOX([from-lport ACL sampling (new)])
 check ovn-nbctl acl-del ls
 check ovn-nbctl --wait=sb --sample-new=$sample1 acl-add ls from-lport 1 "1" allow-related
 AT_CHECK([ovn-sbctl lflow-list | grep -e ls_in_acl_sample -e ls_in_acl_eval -e ls_out_acl_sample | ovn_strip_lflows | ovn_strip_collector_set | grep -e reg3 -e reg9 -e sample], [0], [dnl
-  table=??(ls_in_acl_eval     ), priority=1001 , match=(reg0[[7]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 0; reg8[[0..7]] = 0; reg2[[16..23]] = 0; reg8[[19]] = 0; next;)
-  table=??(ls_in_acl_eval     ), priority=1001 , match=(reg0[[8]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 0; reg8[[0..7]] = 0; reg2[[16..23]] = 0; reg8[[19]] = 0; next;)
+  table=??(ls_in_acl_eval     ), priority=1001 , match=(reg0[[7]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 0; reg8[[0..7]] = 0; reg2[[16..23]] = 0; reg8[[19..20]] = 0; next;)
+  table=??(ls_in_acl_eval     ), priority=1001 , match=(reg0[[8]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 0; reg8[[0..7]] = 0; reg2[[16..23]] = 0; reg8[[19..20]] = 0; next;)
   table=??(ls_in_acl_sample   ), priority=0    , match=(1), action=(next;)
   table=??(ls_in_acl_sample   ), priority=1100 , match=(ip && ct.new && reg3 == 4301), action=(sample(probability=65535,collector_set=??,obs_domain=42,obs_point=4301);sample(probability=65535,collector_set=??,obs_domain=42,obs_point=4301); next;)
   table=??(ls_out_acl_sample  ), priority=0    , match=(1), action=(next;)
@@ -12639,7 +12639,7 @@ AT_CHECK([ovn-sbctl lflow-list | grep -e ls_in_acl_sample -e ls_in_acl_eval -e l
 dnl Trace new connections.
 flow="$base_flow"
 AT_CHECK_UNQUOTED([ovn_trace --ct new ls "$flow" | TRACE_FILTER], [0], [dnl
-    ct_commit { ct_mark.blocked = 0; ct_mark.obs_after_lb = reg8[[19]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; };
+    ct_commit { ct_mark.blocked = 0; ct_mark.obs_stage = reg8[[19..20]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; };
     reg9 = 0;
     sample(probability=65535,collector_set=1,obs_domain=42,obs_point=4301);
     sample(probability=65535,collector_set=2,obs_domain=42,obs_point=4301);
@@ -12656,8 +12656,8 @@ AS_BOX([from-lport-after-lb ACL sampling (new, est)])
 check ovn-nbctl acl-del ls
 check ovn-nbctl --wait=sb --apply-after-lb --sample-new=$sample1 --sample-est=$sample2 acl-add ls from-lport 1 "1" allow-related
 AT_CHECK([ovn-sbctl lflow-list | grep -e ls_in_acl_after_lb_sample -e ls_in_acl_after_lb_eval -e ls_out_acl_sample | ovn_strip_lflows | ovn_strip_collector_set | grep -e reg3 -e reg9 -e sample], [0], [dnl
-  table=??(ls_in_acl_after_lb_eval), priority=1001 , match=(reg0[[7]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 4302; reg8[[0..7]] = 0; reg2[[16..23]] = 0; reg8[[19]] = 1; next;)
-  table=??(ls_in_acl_after_lb_eval), priority=1001 , match=(reg0[[8]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 4302; reg8[[0..7]] = 0; reg2[[16..23]] = 0; reg8[[19]] = 1; next;)
+  table=??(ls_in_acl_after_lb_eval), priority=1001 , match=(reg0[[7]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 4302; reg8[[0..7]] = 0; reg2[[16..23]] = 0; reg8[[19..20]] = 1; next;)
+  table=??(ls_in_acl_after_lb_eval), priority=1001 , match=(reg0[[8]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 4302; reg8[[0..7]] = 0; reg2[[16..23]] = 0; reg8[[19..20]] = 1; next;)
   table=??(ls_in_acl_after_lb_sample), priority=0    , match=(1), action=(next;)
   table=??(ls_in_acl_after_lb_sample), priority=1100 , match=(ip && ct.new && reg3 == 4301), action=(sample(probability=65535,collector_set=??,obs_domain=42,obs_point=4301);sample(probability=65535,collector_set=??,obs_domain=42,obs_point=4301); next;)
   table=??(ls_in_acl_after_lb_sample), priority=1200 , match=(ip && ct.trk && (ct.est || ct.rel) && !ct.rpl && ct_label.obs_point_id == 4302 && ct_label.obs_unused == 0), action=(sample(probability=65535,collector_set=??,obs_domain=43,obs_point=4302);sample(probability=65535,collector_set=??,obs_domain=43,obs_point=4302); next;)
@@ -12668,7 +12668,7 @@ AT_CHECK([ovn-sbctl lflow-list | grep -e ls_in_acl_after_lb_sample -e ls_in_acl_
 dnl Trace new connections.
 flow="$base_flow"
 AT_CHECK_UNQUOTED([ovn_trace --ct new ls "$flow" | TRACE_FILTER], [0], [dnl
-    ct_commit { ct_mark.blocked = 0; ct_mark.obs_after_lb = reg8[[19]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; };
+    ct_commit { ct_mark.blocked = 0; ct_mark.obs_stage = reg8[[19..20]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; };
     reg9 = 4302;
     sample(probability=65535,collector_set=1,obs_domain=42,obs_point=4301);
     sample(probability=65535,collector_set=2,obs_domain=42,obs_point=4301);
@@ -12686,8 +12686,8 @@ AS_BOX([from-lport-after-lb ACL sampling (new)])
 check ovn-nbctl acl-del ls
 check ovn-nbctl --wait=sb --apply-after-lb --sample-new=$sample1 acl-add ls from-lport 1 "1" allow-related
 AT_CHECK([ovn-sbctl lflow-list | grep -e ls_in_acl_after_lb_sample -e ls_in_acl_after_lb_eval -e ls_out_acl_sample | ovn_strip_lflows | ovn_strip_collector_set | grep -e reg3 -e reg9 -e sample], [0], [dnl
-  table=??(ls_in_acl_after_lb_eval), priority=1001 , match=(reg0[[7]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 0; reg8[[0..7]] = 0; reg2[[16..23]] = 0; reg8[[19]] = 1; next;)
-  table=??(ls_in_acl_after_lb_eval), priority=1001 , match=(reg0[[8]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 0; reg8[[0..7]] = 0; reg2[[16..23]] = 0; reg8[[19]] = 1; next;)
+  table=??(ls_in_acl_after_lb_eval), priority=1001 , match=(reg0[[7]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 0; reg8[[0..7]] = 0; reg2[[16..23]] = 0; reg8[[19..20]] = 1; next;)
+  table=??(ls_in_acl_after_lb_eval), priority=1001 , match=(reg0[[8]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 0; reg8[[0..7]] = 0; reg2[[16..23]] = 0; reg8[[19..20]] = 1; next;)
   table=??(ls_in_acl_after_lb_sample), priority=0    , match=(1), action=(next;)
   table=??(ls_in_acl_after_lb_sample), priority=1100 , match=(ip && ct.new && reg3 == 4301), action=(sample(probability=65535,collector_set=??,obs_domain=42,obs_point=4301);sample(probability=65535,collector_set=??,obs_domain=42,obs_point=4301); next;)
   table=??(ls_out_acl_sample  ), priority=0    , match=(1), action=(next;)
@@ -12696,7 +12696,7 @@ AT_CHECK([ovn-sbctl lflow-list | grep -e ls_in_acl_after_lb_sample -e ls_in_acl_
 dnl Trace new connections.
 flow="$base_flow"
 AT_CHECK_UNQUOTED([ovn_trace --ct new ls "$flow" | TRACE_FILTER], [0], [dnl
-    ct_commit { ct_mark.blocked = 0; ct_mark.obs_after_lb = reg8[[19]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; };
+    ct_commit { ct_mark.blocked = 0; ct_mark.obs_stage = reg8[[19..20]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; };
     reg9 = 0;
     sample(probability=65535,collector_set=1,obs_domain=42,obs_point=4301);
     sample(probability=65535,collector_set=2,obs_domain=42,obs_point=4301);
@@ -12715,8 +12715,8 @@ check ovn-nbctl --wait=sb --sample-new=$sample1 --sample-est=$sample2 acl-add ls
 AT_CHECK([ovn-sbctl lflow-list | grep -e ls_out_acl_sample -e ls_out_acl_eval -e ls_in_acl_sample | ovn_strip_lflows | ovn_strip_collector_set | grep -e reg3 -e reg9 -e sample], [0], [dnl
   table=??(ls_in_acl_sample   ), priority=0    , match=(1), action=(next;)
   table=??(ls_in_acl_sample   ), priority=1200 , match=(ip && ct.trk && (ct.est || ct.rel) && ct.rpl && ct_label.obs_point_id == 4302 && ct_label.obs_unused == 0), action=(sample(probability=65535,collector_set=??,obs_domain=43,obs_point=4302);sample(probability=65535,collector_set=??,obs_domain=43,obs_point=4302); next;)
-  table=??(ls_out_acl_eval    ), priority=1001 , match=(reg0[[7]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 4302; reg8[[0..7]] = 0; reg2[[16..23]] = 0; reg8[[19]] = 0; next;)
-  table=??(ls_out_acl_eval    ), priority=1001 , match=(reg0[[8]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 4302; reg8[[0..7]] = 0; reg2[[16..23]] = 0; reg8[[19]] = 0; next;)
+  table=??(ls_out_acl_eval    ), priority=1001 , match=(reg0[[7]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 4302; reg8[[0..7]] = 0; reg2[[16..23]] = 0; reg8[[19..20]] = 2; next;)
+  table=??(ls_out_acl_eval    ), priority=1001 , match=(reg0[[8]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 4302; reg8[[0..7]] = 0; reg2[[16..23]] = 0; reg8[[19..20]] = 2; next;)
   table=??(ls_out_acl_sample  ), priority=0    , match=(1), action=(next;)
   table=??(ls_out_acl_sample  ), priority=1100 , match=(ip && ct.new && reg3 == 4301), action=(sample(probability=65535,collector_set=??,obs_domain=42,obs_point=4301);sample(probability=65535,collector_set=??,obs_domain=42,obs_point=4301); next;)
   table=??(ls_out_acl_sample  ), priority=1200 , match=(ip && ct.trk && (ct.est || ct.rel) && !ct.rpl && ct_label.obs_point_id == 4302 && ct_label.obs_unused == 0), action=(sample(probability=65535,collector_set=??,obs_domain=43,obs_point=4302);sample(probability=65535,collector_set=??,obs_domain=43,obs_point=4302); next;)
@@ -12725,7 +12725,7 @@ AT_CHECK([ovn-sbctl lflow-list | grep -e ls_out_acl_sample -e ls_out_acl_eval -e
 dnl Trace new connections.
 flow="$base_flow"
 AT_CHECK_UNQUOTED([ovn_trace --ct new --ct new ls "$flow" | TRACE_FILTER], [0], [dnl
-    ct_commit { ct_mark.blocked = 0; ct_mark.obs_after_lb = reg8[[19]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; };
+    ct_commit { ct_mark.blocked = 0; ct_mark.obs_stage = reg8[[19..20]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; };
     ct_commit { ct_mark.blocked = 0; };
     reg9 = 4302;
     sample(probability=65535,collector_set=1,obs_domain=42,obs_point=4301);
@@ -12745,8 +12745,8 @@ check ovn-nbctl acl-del ls
 check ovn-nbctl --wait=sb --sample-new=$sample1 acl-add ls to-lport 1 "1" allow-related
 AT_CHECK([ovn-sbctl lflow-list | grep -e ls_out_acl_sample -e ls_out_acl_eval -e ls_in_acl_sample | ovn_strip_lflows | ovn_strip_collector_set | grep -e reg3 -e reg9 -e sample], [0], [dnl
   table=??(ls_in_acl_sample   ), priority=0    , match=(1), action=(next;)
-  table=??(ls_out_acl_eval    ), priority=1001 , match=(reg0[[7]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 0; reg8[[0..7]] = 0; reg2[[16..23]] = 0; reg8[[19]] = 0; next;)
-  table=??(ls_out_acl_eval    ), priority=1001 , match=(reg0[[8]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 0; reg8[[0..7]] = 0; reg2[[16..23]] = 0; reg8[[19]] = 0; next;)
+  table=??(ls_out_acl_eval    ), priority=1001 , match=(reg0[[7]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 0; reg8[[0..7]] = 0; reg2[[16..23]] = 0; reg8[[19..20]] = 2; next;)
+  table=??(ls_out_acl_eval    ), priority=1001 , match=(reg0[[8]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 0; reg8[[0..7]] = 0; reg2[[16..23]] = 0; reg8[[19..20]] = 2; next;)
   table=??(ls_out_acl_sample  ), priority=0    , match=(1), action=(next;)
   table=??(ls_out_acl_sample  ), priority=1100 , match=(ip && ct.new && reg3 == 4301), action=(sample(probability=65535,collector_set=??,obs_domain=42,obs_point=4301);sample(probability=65535,collector_set=??,obs_domain=42,obs_point=4301); next;)
 ])
@@ -12754,7 +12754,7 @@ AT_CHECK([ovn-sbctl lflow-list | grep -e ls_out_acl_sample -e ls_out_acl_eval -e
 dnl Trace new connections.
 flow="$base_flow"
 AT_CHECK_UNQUOTED([ovn_trace --ct new --ct new ls "$flow" | TRACE_FILTER], [0], [dnl
-    ct_commit { ct_mark.blocked = 0; ct_mark.obs_after_lb = reg8[[19]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; };
+    ct_commit { ct_mark.blocked = 0; ct_mark.obs_stage = reg8[[19..20]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; };
     ct_commit { ct_mark.blocked = 0; };
     reg9 = 0;
     sample(probability=65535,collector_set=1,obs_domain=42,obs_point=4301);
@@ -12806,8 +12806,8 @@ check ovn-sbctl chassis-add gw1 geneve 127.0.0.1 \
 check ovn-nbctl acl-del ls
 check ovn-nbctl --wait=sb --sample-new=$sample1 --sample-est=$sample2 acl-add ls from-lport 1 "1" allow-related
 AT_CHECK([ovn-sbctl lflow-list | grep -e ls_in_acl_sample -e ls_in_acl_eval -e ls_out_acl_sample | ovn_strip_lflows | ovn_strip_collector_set | grep -e reg3 -e reg9 -e sample], [0], [dnl
-  table=??(ls_in_acl_eval     ), priority=1001 , match=(reg0[[7]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 4302; reg8[[0..7]] = 1; reg2[[16..23]] = 1; reg8[[19]] = 0; next;)
-  table=??(ls_in_acl_eval     ), priority=1001 , match=(reg0[[8]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 4302; reg8[[0..7]] = 1; reg2[[16..23]] = 1; reg8[[19]] = 0; next;)
+  table=??(ls_in_acl_eval     ), priority=1001 , match=(reg0[[7]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 4302; reg8[[0..7]] = 1; reg2[[16..23]] = 1; reg8[[19..20]] = 0; next;)
+  table=??(ls_in_acl_eval     ), priority=1001 , match=(reg0[[8]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 4302; reg8[[0..7]] = 1; reg2[[16..23]] = 1; reg8[[19..20]] = 0; next;)
   table=??(ls_in_acl_sample   ), priority=0    , match=(1), action=(next;)
   table=??(ls_in_acl_sample   ), priority=1100 , match=(ip && ct.new && reg3 == 4301), action=(sample(probability=65535,collector_set=??,obs_domain=42,obs_point=4301); next;)
   table=??(ls_in_acl_sample   ), priority=1200 , match=(ip && ct.trk && (ct.est || ct.rel) && !ct.rpl && ct_label.obs_point_id == 4302 && ct_label.obs_unused == 0), action=(sample(probability=65535,collector_set=??,obs_domain=43,obs_point=4302); next;)
@@ -12818,7 +12818,7 @@ AT_CHECK([ovn-sbctl lflow-list | grep -e ls_in_acl_sample -e ls_in_acl_eval -e l
 dnl Trace new connections.
 flow="$base_flow"
 AT_CHECK_UNQUOTED([ovn_trace --ct new ls "$flow" | TRACE_FILTER], [0], [dnl
-    ct_commit { ct_mark.blocked = 0; ct_mark.obs_after_lb = reg8[[19]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; };
+    ct_commit { ct_mark.blocked = 0; ct_mark.obs_stage = reg8[[19..20]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; };
     reg2[[16..23]] = 1;
     reg9 = 4302;
     sample(probability=65535,collector_set=1,obs_domain=42,obs_point=4301);
@@ -12839,11 +12839,11 @@ AS_BOX([from-lport ACL sampling (new, est)])
 check ovn-nbctl acl-del ls
 check ovn-nbctl --wait=sb --sample-new=$sample1 --sample-est=$sample2 acl-add ls from-lport 1 "1" allow-related
 AT_CHECK([ovn-sbctl lflow-list | grep -e ls_in_acl_sample -e ls_in_acl_eval -e ls_out_acl_sample | ovn_strip_lflows | ovn_strip_collector_set | grep -e reg3 -e reg9 -e sample], [0], [dnl
-  table=??(ls_in_acl_eval     ), priority=1001 , match=(reg0[[7]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 4302; reg8[[0..7]] = 1; reg2[[16..23]] = 1; reg8[[19]] = 0; next;)
-  table=??(ls_in_acl_eval     ), priority=1001 , match=(reg0[[8]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 4302; reg8[[0..7]] = 1; reg2[[16..23]] = 1; reg8[[19]] = 0; next;)
+  table=??(ls_in_acl_eval     ), priority=1001 , match=(reg0[[7]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 4302; reg8[[0..7]] = 1; reg2[[16..23]] = 1; reg8[[19..20]] = 0; next;)
+  table=??(ls_in_acl_eval     ), priority=1001 , match=(reg0[[8]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 4302; reg8[[0..7]] = 1; reg2[[16..23]] = 1; reg8[[19..20]] = 0; next;)
   table=??(ls_in_acl_sample   ), priority=0    , match=(1), action=(next;)
-  table=??(ls_in_acl_sample   ), priority=1000 , match=(ip && ct.new && reg8[[0..7]] == 1 && reg8[[19]] == 0), action=(sample(probability=65535,collector_set=??,obs_domain=42,obs_point=reg3); next;)
-  table=??(ls_in_acl_sample   ), priority=1000 , match=(ip && ct.trk && (ct.est || ct.rel) && ct_label.obs_unused == 0 && !ct.rpl && ct_mark.obs_collector_id == 1 && ct_mark.obs_after_lb == 0), action=(sample(probability=65535,collector_set=??,obs_domain=43,obs_point=ct_label.obs_point_id); next;)
+  table=??(ls_in_acl_sample   ), priority=1000 , match=(ip && ct.new && reg8[[0..7]] == 1 && reg8[[19..20]] == 0), action=(sample(probability=65535,collector_set=??,obs_domain=42,obs_point=reg3); next;)
+  table=??(ls_in_acl_sample   ), priority=1000 , match=(ip && ct.trk && (ct.est || ct.rel) && ct_label.obs_unused == 0 && !ct.rpl && ct_mark.obs_collector_id == 1 && ct_mark.obs_stage == 0), action=(sample(probability=65535,collector_set=??,obs_domain=43,obs_point=ct_label.obs_point_id); next;)
   table=??(ls_out_acl_sample  ), priority=0    , match=(1), action=(next;)
   table=??(ls_out_acl_sample  ), priority=1000 , match=(ip && ct.trk && (ct.est || ct.rel) && ct_label.obs_unused == 0 && ct.rpl && ct_mark.obs_collector_id == 1), action=(sample(probability=65535,collector_set=??,obs_domain=43,obs_point=ct_label.obs_point_id); next;)
 ])
@@ -12851,14 +12851,14 @@ AT_CHECK([ovn-sbctl lflow-list | grep -e ls_in_acl_sample -e ls_in_acl_eval -e l
 dnl Trace new connections.
 flow="$base_flow"
 AT_CHECK_UNQUOTED([ovn_trace --ct new ls "$flow" | TRACE_FILTER], [0], [dnl
-    ct_commit { ct_mark.blocked = 0; ct_mark.obs_after_lb = reg8[[19]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; };
+    ct_commit { ct_mark.blocked = 0; ct_mark.obs_stage = reg8[[19..20]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; };
     reg2[[16..23]] = 1;
     reg9 = 4302;
     sample(probability=65535,collector_set=1,obs_domain=42,obs_point=reg3);
 ])
 
 dnl Trace estasblished connections.
-flow="$base_flow && ct_label.obs_point_id == 4302 && ct_mark.obs_after_lb == 0 && ct_mark.obs_collector_id == 1"
+flow="$base_flow && ct_label.obs_point_id == 4302 && ct_mark.obs_stage == 0 && ct_mark.obs_collector_id == 1"
 AT_CHECK_UNQUOTED([ovn_trace --ct est ls "$flow" | TRACE_FILTER], [0], [dnl
     reg2[[16..23]] = 1;
     reg9 = 4302;
@@ -12869,17 +12869,17 @@ AS_BOX([from-lport ACL sampling (new)])
 check ovn-nbctl acl-del ls
 check ovn-nbctl --wait=sb --sample-new=$sample1 acl-add ls from-lport 1 "1" allow-related
 AT_CHECK([ovn-sbctl lflow-list | grep -e ls_in_acl_sample -e ls_in_acl_eval -e ls_out_acl_sample | ovn_strip_lflows | ovn_strip_collector_set | grep -e reg3 -e reg9 -e sample], [0], [dnl
-  table=??(ls_in_acl_eval     ), priority=1001 , match=(reg0[[7]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 0; reg8[[0..7]] = 1; reg2[[16..23]] = 0; reg8[[19]] = 0; next;)
-  table=??(ls_in_acl_eval     ), priority=1001 , match=(reg0[[8]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 0; reg8[[0..7]] = 1; reg2[[16..23]] = 0; reg8[[19]] = 0; next;)
+  table=??(ls_in_acl_eval     ), priority=1001 , match=(reg0[[7]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 0; reg8[[0..7]] = 1; reg2[[16..23]] = 0; reg8[[19..20]] = 0; next;)
+  table=??(ls_in_acl_eval     ), priority=1001 , match=(reg0[[8]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 0; reg8[[0..7]] = 1; reg2[[16..23]] = 0; reg8[[19..20]] = 0; next;)
   table=??(ls_in_acl_sample   ), priority=0    , match=(1), action=(next;)
-  table=??(ls_in_acl_sample   ), priority=1000 , match=(ip && ct.new && reg8[[0..7]] == 1 && reg8[[19]] == 0), action=(sample(probability=65535,collector_set=??,obs_domain=42,obs_point=reg3); next;)
+  table=??(ls_in_acl_sample   ), priority=1000 , match=(ip && ct.new && reg8[[0..7]] == 1 && reg8[[19..20]] == 0), action=(sample(probability=65535,collector_set=??,obs_domain=42,obs_point=reg3); next;)
   table=??(ls_out_acl_sample  ), priority=0    , match=(1), action=(next;)
 ])
 
 dnl Trace new connections.
 flow="$base_flow"
 AT_CHECK_UNQUOTED([ovn_trace --ct new ls "$flow" | TRACE_FILTER], [0], [dnl
-    ct_commit { ct_mark.blocked = 0; ct_mark.obs_after_lb = reg8[[19]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; };
+    ct_commit { ct_mark.blocked = 0; ct_mark.obs_stage = reg8[[19..20]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; };
     reg2[[16..23]] = 0;
     reg9 = 0;
     sample(probability=65535,collector_set=1,obs_domain=42,obs_point=reg3);
@@ -12887,7 +12887,7 @@ AT_CHECK_UNQUOTED([ovn_trace --ct new ls "$flow" | TRACE_FILTER], [0], [dnl
 
 dnl Trace established connections (no point id was committed in the label in
 dnl the original direction).
-flow="$base_flow && ct_label.obs_point_id == 0 && ct_mark.obs_after_lb == 0 && ct_mark.obs_collector_id == 0"
+flow="$base_flow && ct_label.obs_point_id == 0 && ct_mark.obs_stage == 0 && ct_mark.obs_collector_id == 0"
 AT_CHECK_UNQUOTED([ovn_trace --ct est ls "$flow" | TRACE_FILTER], [0], [dnl
     reg2[[16..23]] = 0;
     reg9 = 0;
@@ -12897,11 +12897,11 @@ AS_BOX([from-lport-after-lb ACL sampling (new, est)])
 check ovn-nbctl acl-del ls
 check ovn-nbctl --wait=sb --apply-after-lb --sample-new=$sample1 --sample-est=$sample2 acl-add ls from-lport 1 "1" allow-related
 AT_CHECK([ovn-sbctl lflow-list | grep -e ls_in_acl_after_lb_sample -e ls_in_acl_after_lb_eval -e ls_out_acl_sample | ovn_strip_lflows | ovn_strip_collector_set | grep -e reg3 -e reg9 -e sample], [0], [dnl
-  table=??(ls_in_acl_after_lb_eval), priority=1001 , match=(reg0[[7]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 4302; reg8[[0..7]] = 1; reg2[[16..23]] = 1; reg8[[19]] = 1; next;)
-  table=??(ls_in_acl_after_lb_eval), priority=1001 , match=(reg0[[8]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 4302; reg8[[0..7]] = 1; reg2[[16..23]] = 1; reg8[[19]] = 1; next;)
+  table=??(ls_in_acl_after_lb_eval), priority=1001 , match=(reg0[[7]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 4302; reg8[[0..7]] = 1; reg2[[16..23]] = 1; reg8[[19..20]] = 1; next;)
+  table=??(ls_in_acl_after_lb_eval), priority=1001 , match=(reg0[[8]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 4302; reg8[[0..7]] = 1; reg2[[16..23]] = 1; reg8[[19..20]] = 1; next;)
   table=??(ls_in_acl_after_lb_sample), priority=0    , match=(1), action=(next;)
-  table=??(ls_in_acl_after_lb_sample), priority=1000 , match=(ip && ct.new && reg8[[0..7]] == 1 && reg8[[19]] == 1), action=(sample(probability=65535,collector_set=??,obs_domain=42,obs_point=reg3); next;)
-  table=??(ls_in_acl_after_lb_sample), priority=1000 , match=(ip && ct.trk && (ct.est || ct.rel) && ct_label.obs_unused == 0 && !ct.rpl && ct_mark.obs_collector_id == 1 && ct_mark.obs_after_lb == 1), action=(sample(probability=65535,collector_set=??,obs_domain=43,obs_point=ct_label.obs_point_id); next;)
+  table=??(ls_in_acl_after_lb_sample), priority=1000 , match=(ip && ct.new && reg8[[0..7]] == 1 && reg8[[19..20]] == 1), action=(sample(probability=65535,collector_set=??,obs_domain=42,obs_point=reg3); next;)
+  table=??(ls_in_acl_after_lb_sample), priority=1000 , match=(ip && ct.trk && (ct.est || ct.rel) && ct_label.obs_unused == 0 && !ct.rpl && ct_mark.obs_collector_id == 1 && ct_mark.obs_stage == 1), action=(sample(probability=65535,collector_set=??,obs_domain=43,obs_point=ct_label.obs_point_id); next;)
   table=??(ls_out_acl_sample  ), priority=0    , match=(1), action=(next;)
   table=??(ls_out_acl_sample  ), priority=1000 , match=(ip && ct.trk && (ct.est || ct.rel) && ct_label.obs_unused == 0 && ct.rpl && ct_mark.obs_collector_id == 1), action=(sample(probability=65535,collector_set=??,obs_domain=43,obs_point=ct_label.obs_point_id); next;)
 ])
@@ -12909,14 +12909,14 @@ AT_CHECK([ovn-sbctl lflow-list | grep -e ls_in_acl_after_lb_sample -e ls_in_acl_
 dnl Trace new connections.
 flow="$base_flow"
 AT_CHECK_UNQUOTED([ovn_trace --ct new ls "$flow" | TRACE_FILTER], [0], [dnl
-    ct_commit { ct_mark.blocked = 0; ct_mark.obs_after_lb = reg8[[19]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; };
+    ct_commit { ct_mark.blocked = 0; ct_mark.obs_stage = reg8[[19..20]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; };
     reg2[[16..23]] = 1;
     reg9 = 4302;
     sample(probability=65535,collector_set=1,obs_domain=42,obs_point=reg3);
 ])
 
 dnl Trace estasblished connections.
-flow="$base_flow && ct_label.obs_point_id == 4302 && ct_mark.obs_after_lb == 1 && ct_mark.obs_collector_id == 1"
+flow="$base_flow && ct_label.obs_point_id == 4302 && ct_mark.obs_stage == 1 && ct_mark.obs_collector_id == 1"
 AT_CHECK_UNQUOTED([ovn_trace --ct est ls "$flow" | TRACE_FILTER], [0], [dnl
     reg2[[16..23]] = 1;
     reg9 = 4302;
@@ -12927,17 +12927,17 @@ AS_BOX([from-lport-after-lb ACL sampling (new)])
 check ovn-nbctl acl-del ls
 check ovn-nbctl --wait=sb --apply-after-lb --sample-new=$sample1 acl-add ls from-lport 1 "1" allow-related
 AT_CHECK([ovn-sbctl lflow-list | grep -e ls_in_acl_after_lb_sample -e ls_in_acl_after_lb_eval -e ls_out_acl_sample | ovn_strip_lflows | ovn_strip_collector_set | grep -e reg3 -e reg9 -e sample], [0], [dnl
-  table=??(ls_in_acl_after_lb_eval), priority=1001 , match=(reg0[[7]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 0; reg8[[0..7]] = 1; reg2[[16..23]] = 0; reg8[[19]] = 1; next;)
-  table=??(ls_in_acl_after_lb_eval), priority=1001 , match=(reg0[[8]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 0; reg8[[0..7]] = 1; reg2[[16..23]] = 0; reg8[[19]] = 1; next;)
+  table=??(ls_in_acl_after_lb_eval), priority=1001 , match=(reg0[[7]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 0; reg8[[0..7]] = 1; reg2[[16..23]] = 0; reg8[[19..20]] = 1; next;)
+  table=??(ls_in_acl_after_lb_eval), priority=1001 , match=(reg0[[8]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 0; reg8[[0..7]] = 1; reg2[[16..23]] = 0; reg8[[19..20]] = 1; next;)
   table=??(ls_in_acl_after_lb_sample), priority=0    , match=(1), action=(next;)
-  table=??(ls_in_acl_after_lb_sample), priority=1000 , match=(ip && ct.new && reg8[[0..7]] == 1 && reg8[[19]] == 1), action=(sample(probability=65535,collector_set=??,obs_domain=42,obs_point=reg3); next;)
+  table=??(ls_in_acl_after_lb_sample), priority=1000 , match=(ip && ct.new && reg8[[0..7]] == 1 && reg8[[19..20]] == 1), action=(sample(probability=65535,collector_set=??,obs_domain=42,obs_point=reg3); next;)
   table=??(ls_out_acl_sample  ), priority=0    , match=(1), action=(next;)
 ])
 
 dnl Trace new connections.
 flow="$base_flow"
 AT_CHECK_UNQUOTED([ovn_trace --ct new ls "$flow" | TRACE_FILTER], [0], [dnl
-    ct_commit { ct_mark.blocked = 0; ct_mark.obs_after_lb = reg8[[19]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; };
+    ct_commit { ct_mark.blocked = 0; ct_mark.obs_stage = reg8[[19..20]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; };
     reg2[[16..23]] = 0;
     reg9 = 0;
     sample(probability=65535,collector_set=1,obs_domain=42,obs_point=reg3);
@@ -12945,7 +12945,7 @@ AT_CHECK_UNQUOTED([ovn_trace --ct new ls "$flow" | TRACE_FILTER], [0], [dnl
 
 dnl Trace established connections (no point id was committed in the label in
 dnl the original direction).
-flow="$base_flow && ct_label.obs_point_id == 0 && ct_mark.obs_after_lb == 0 && ct_mark.obs_collector_id == 0"
+flow="$base_flow && ct_label.obs_point_id == 0 && ct_mark.obs_stage == 0 && ct_mark.obs_collector_id == 0"
 AT_CHECK_UNQUOTED([ovn_trace --ct est ls "$flow" | TRACE_FILTER], [0], [dnl
     reg2[[16..23]] = 0;
     reg9 = 0;
@@ -12957,17 +12957,17 @@ check ovn-nbctl --wait=sb --sample-new=$sample1 --sample-est=$sample2 acl-add ls
 AT_CHECK([ovn-sbctl lflow-list | grep -e ls_out_acl_sample -e ls_out_acl_eval -e ls_in_acl_sample | ovn_strip_lflows | ovn_strip_collector_set | grep -e reg3 -e reg9 -e sample], [0], [dnl
   table=??(ls_in_acl_sample   ), priority=0    , match=(1), action=(next;)
   table=??(ls_in_acl_sample   ), priority=1000 , match=(ip && ct.trk && (ct.est || ct.rel) && ct_label.obs_unused == 0 && ct.rpl && ct_mark.obs_collector_id == 1), action=(sample(probability=65535,collector_set=??,obs_domain=43,obs_point=ct_label.obs_point_id); next;)
-  table=??(ls_out_acl_eval    ), priority=1001 , match=(reg0[[7]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 4302; reg8[[0..7]] = 1; reg2[[16..23]] = 1; reg8[[19]] = 0; next;)
-  table=??(ls_out_acl_eval    ), priority=1001 , match=(reg0[[8]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 4302; reg8[[0..7]] = 1; reg2[[16..23]] = 1; reg8[[19]] = 0; next;)
+  table=??(ls_out_acl_eval    ), priority=1001 , match=(reg0[[7]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 4302; reg8[[0..7]] = 1; reg2[[16..23]] = 1; reg8[[19..20]] = 2; next;)
+  table=??(ls_out_acl_eval    ), priority=1001 , match=(reg0[[8]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 4302; reg8[[0..7]] = 1; reg2[[16..23]] = 1; reg8[[19..20]] = 2; next;)
   table=??(ls_out_acl_sample  ), priority=0    , match=(1), action=(next;)
-  table=??(ls_out_acl_sample  ), priority=1000 , match=(ip && ct.new && reg8[[0..7]] == 1 && reg8[[19]] == 0), action=(sample(probability=65535,collector_set=??,obs_domain=42,obs_point=reg3); next;)
-  table=??(ls_out_acl_sample  ), priority=1000 , match=(ip && ct.trk && (ct.est || ct.rel) && ct_label.obs_unused == 0 && !ct.rpl && ct_mark.obs_collector_id == 1 && ct_mark.obs_after_lb == 0), action=(sample(probability=65535,collector_set=??,obs_domain=43,obs_point=ct_label.obs_point_id); next;)
+  table=??(ls_out_acl_sample  ), priority=1000 , match=(ip && ct.new && reg8[[0..7]] == 1 && reg8[[19..20]] == 2), action=(sample(probability=65535,collector_set=??,obs_domain=42,obs_point=reg3); next;)
+  table=??(ls_out_acl_sample  ), priority=1000 , match=(ip && ct.trk && (ct.est || ct.rel) && ct_label.obs_unused == 0 && !ct.rpl && ct_mark.obs_collector_id == 1 && ct_mark.obs_stage == 2), action=(sample(probability=65535,collector_set=??,obs_domain=43,obs_point=ct_label.obs_point_id); next;)
 ])
 
 dnl Trace new connections.
 flow="$base_flow"
 AT_CHECK_UNQUOTED([ovn_trace --ct new --ct new ls "$flow" | TRACE_FILTER], [0], [dnl
-    ct_commit { ct_mark.blocked = 0; ct_mark.obs_after_lb = reg8[[19]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; };
+    ct_commit { ct_mark.blocked = 0; ct_mark.obs_stage = reg8[[19..20]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; };
     ct_commit { ct_mark.blocked = 0; };
     reg2[[16..23]] = 1;
     reg9 = 4302;
@@ -12975,7 +12975,7 @@ AT_CHECK_UNQUOTED([ovn_trace --ct new --ct new ls "$flow" | TRACE_FILTER], [0],
 ])
 
 dnl Trace estasblished connections.
-flow="$base_flow && ct_label.obs_point_id == 4302 && ct_mark.obs_after_lb == 0 && ct_mark.obs_collector_id == 1"
+flow="$base_flow && ct_label.obs_point_id == 4302 && ct_mark.obs_stage == 2 && ct_mark.obs_collector_id == 1"
 AT_CHECK_UNQUOTED([ovn_trace --ct est --ct est ls "$flow" | TRACE_FILTER], [0], [dnl
     reg2[[16..23]] = 1;
     reg9 = 4302;
@@ -12987,16 +12987,16 @@ check ovn-nbctl acl-del ls
 check ovn-nbctl --wait=sb --sample-new=$sample1 acl-add ls to-lport 1 "1" allow-related
 AT_CHECK([ovn-sbctl lflow-list | grep -e ls_out_acl_sample -e ls_out_acl_eval -e ls_in_acl_sample | ovn_strip_lflows | ovn_strip_collector_set | grep -e reg3 -e reg9 -e sample], [0], [dnl
   table=??(ls_in_acl_sample   ), priority=0    , match=(1), action=(next;)
-  table=??(ls_out_acl_eval    ), priority=1001 , match=(reg0[[7]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 0; reg8[[0..7]] = 1; reg2[[16..23]] = 0; reg8[[19]] = 0; next;)
-  table=??(ls_out_acl_eval    ), priority=1001 , match=(reg0[[8]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 0; reg8[[0..7]] = 1; reg2[[16..23]] = 0; reg8[[19]] = 0; next;)
+  table=??(ls_out_acl_eval    ), priority=1001 , match=(reg0[[7]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[1]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 0; reg8[[0..7]] = 1; reg2[[16..23]] = 0; reg8[[19..20]] = 2; next;)
+  table=??(ls_out_acl_eval    ), priority=1001 , match=(reg0[[8]] == 1 && (1)), action=(reg8[[16]] = 1; reg0[[13]] = 1; reg3 = 4301; reg9 = 0; reg8[[0..7]] = 1; reg2[[16..23]] = 0; reg8[[19..20]] = 2; next;)
   table=??(ls_out_acl_sample  ), priority=0    , match=(1), action=(next;)
-  table=??(ls_out_acl_sample  ), priority=1000 , match=(ip && ct.new && reg8[[0..7]] == 1 && reg8[[19]] == 0), action=(sample(probability=65535,collector_set=??,obs_domain=42,obs_point=reg3); next;)
+  table=??(ls_out_acl_sample  ), priority=1000 , match=(ip && ct.new && reg8[[0..7]] == 1 && reg8[[19..20]] == 2), action=(sample(probability=65535,collector_set=??,obs_domain=42,obs_point=reg3); next;)
 ])
 
 dnl Trace new connections.
 flow="$base_flow"
 AT_CHECK_UNQUOTED([ovn_trace --ct new --ct new ls "$flow" | TRACE_FILTER], [0], [dnl
-    ct_commit { ct_mark.blocked = 0; ct_mark.obs_after_lb = reg8[[19]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; };
+    ct_commit { ct_mark.blocked = 0; ct_mark.obs_stage = reg8[[19..20]]; ct_mark.obs_collector_id = reg2[[16..23]]; ct_label.obs_point_id = reg9; };
     ct_commit { ct_mark.blocked = 0; };
     reg2[[16..23]] = 0;
     reg9 = 0;
@@ -13005,7 +13005,7 @@ AT_CHECK_UNQUOTED([ovn_trace --ct new --ct new ls "$flow" | TRACE_FILTER], [0],
 
 dnl Trace established connections (no point id was committed in the label in
 dnl the original direction).
-flow="$base_flow && ct_label.obs_point_id == 0 && ct_mark.obs_after_lb == 0 && ct_mark.obs_collector_id == 0"
+flow="$base_flow && ct_label.obs_point_id == 0 && ct_mark.obs_stage == 2 && ct_mark.obs_collector_id == 0"
 AT_CHECK_UNQUOTED([ovn_trace --ct est --ct est ls "$flow" | TRACE_FILTER], [0], [dnl
     reg2[[16..23]] = 0;
     reg9 = 0;
diff --git a/tests/ovn.at b/tests/ovn.at
index 122cac5529..b4cf495acd 100644
--- a/tests/ovn.at
+++ b/tests/ovn.at
@@ -336,8 +336,8 @@ ct_mark.blocked = ct_mark[0]
 ct_mark.ecmp_reply_port = ct_mark[16..31]
 ct_mark.force_snat = ct_mark[3]
 ct_mark.natted = ct_mark[1]
-ct_mark.obs_after_lb = ct_mark[4]
 ct_mark.obs_collector_id = ct_mark[16..23]
+ct_mark.obs_stage = ct_mark[4..5]
 ct_mark.skip_snat = ct_mark[2]
 ct_state = NXM_NX_CT_STATE
 ]])
diff --git a/tests/system-ovn.at b/tests/system-ovn.at
index b440b6d489..a9cb54b452 100644
--- a/tests/system-ovn.at
+++ b/tests/system-ovn.at
@@ -7724,7 +7724,7 @@ NS_CHECK_EXEC([sw0-p3], [ping -q -c 10 -i 0.3 -w 15 10.0.0.2 | FORMAT_PING], \
 AT_CHECK([ovs-appctl dpctl/dump-conntrack | FORMAT_CT(10.0.0.2) | \
 sed -e 's/zone=[[0-9]]*/zone=<cleared>/' | \
 sed -e 's/labels=0x4d3[[0-9a-f]]*/labels=0x4d3000000000000000000000000/'], [0], [dnl
-icmp,orig=(src=10.0.0.4,dst=10.0.0.2,id=<cleared>,type=8,code=0),reply=(src=10.0.0.2,dst=10.0.0.4,id=<cleared>,type=0,code=0),zone=<cleared>,labels=0x4d3000000000000000000000000
+icmp,orig=(src=10.0.0.4,dst=10.0.0.2,id=<cleared>,type=8,code=0),reply=(src=10.0.0.2,dst=10.0.0.4,id=<cleared>,type=0,code=0),zone=<cleared>,mark=32,labels=0x4d3000000000000000000000000
 icmp,orig=(src=10.0.0.4,dst=10.0.0.2,id=<cleared>,type=8,code=0),reply=(src=10.0.0.2,dst=10.0.0.4,id=<cleared>,type=0,code=0),zone=<cleared>
 ])
 
@@ -7866,7 +7866,7 @@ NS_CHECK_EXEC([sw0-p3], [ping -q -c 10 -i 0.3 -w 15 10.0.0.2 | FORMAT_PING], \
 AT_CHECK([ovs-appctl dpctl/dump-conntrack | FORMAT_CT(10.0.0.2) | \
 sed -e 's/zone=[[0-9]]*/zone=<cleared>/' | \
 sed -e 's/labels=0x4d3[[0-9a-f]]*/labels=0x4d3000000000000000000000000/'], [0], [dnl
-icmp,orig=(src=10.0.0.4,dst=10.0.0.2,id=<cleared>,type=8,code=0),reply=(src=10.0.0.2,dst=10.0.0.4,id=<cleared>,type=0,code=0),zone=<cleared>,labels=0x4d3000000000000000000000000
+icmp,orig=(src=10.0.0.4,dst=10.0.0.2,id=<cleared>,type=8,code=0),reply=(src=10.0.0.2,dst=10.0.0.4,id=<cleared>,type=0,code=0),zone=<cleared>,mark=32,labels=0x4d3000000000000000000000000
 icmp,orig=(src=10.0.0.4,dst=10.0.0.2,id=<cleared>,type=8,code=0),reply=(src=10.0.0.2,dst=10.0.0.4,id=<cleared>,type=0,code=0),zone=<cleared>
 ])