Hi Abhiram,

I had a look through the code and I'm happy with how it looks. I also did a quick check through the testsuite and it all seems good. All that being said,

I nearly acked this, but I have one question down below in the test code. It may indicate some issue in `ovn-nbctl lr-nat-del` so I'd like to get that cleared up first.

On 3/7/22 09:53, Abhiram Sangana wrote:
Currently, if multiple distributed gateway ports (DGP) are configured
on a logical router, NAT is disabled as part of commit 15348b7
(northd: Multiple distributed gateway port support.)

This patch adds a new column called "gateway_port" in NAT table that
references a distributed gateway port in the Logical_Router_Port
table. A NAT rule is only applied on matching packets entering or
leaving the DGP configured for the rule, when a router has
multiple DGPs.

If a router has a single DGP, NAT rules are applied at the DGP even if
the "gateway_port" column is not set. It is an error to not set this
column for a NAT rule when the router has multiple DGPs.

This patch also updates the NAT commands in ovn-nbctl to support the
new column.

Signed-off-by: Abhiram Sangana <sangana.abhi...@nutanix.com>
---
  NEWS                      |   1 +
  northd/northd.c           | 182 +++++++++++++++++++++++---------------
  northd/ovn-northd.8.xml   |  27 +++---
  ovn-architecture.7.xml    |   6 +-
  ovn-nb.ovsschema          |  10 ++-
  ovn-nb.xml                |  37 +++++++-
  tests/ovn-nbctl.at        | 172 +++++++++++++++++++++--------------
  tests/ovn-northd.at       | 166 +++++++++++++++++++++++++++++++++-
  tests/ovn.at              |   2 +-
  utilities/ovn-nbctl.8.xml |  32 ++++---
  utilities/ovn-nbctl.c     | 151 ++++++++++++++++++++++++++-----
  11 files changed, 592 insertions(+), 194 deletions(-)

diff --git a/NEWS b/NEWS
index 9648f6cb2..764b2a03e 100644
--- a/NEWS
+++ b/NEWS
@@ -1,5 +1,6 @@
  Post v22.03.0
  -------------
+  - Support NAT with multiple distributed gateway ports on a logical router.
OVN v22.03.0 - XX XXX XXXX
  --------------------------
diff --git a/northd/northd.c b/northd/northd.c
index 294a59bd7..351f41134 100644
--- a/northd/northd.c
+++ b/northd/northd.c
@@ -604,11 +604,11 @@ struct ovn_datapath {
/* Applies to only logical router datapath.
       * True if logical router is a gateway router. i.e options:chassis is set.
-     * If this is true, then 'l3dgw_port' will be ignored. */
+     * If this is true, then 'l3dgw_ports' will be ignored. */
      bool is_gw_router;
- /* OVN northd only needs to know about the logical router gateway port for
-     * NAT on a distributed router.  The "distributed gateway ports" are
+    /* OVN northd only needs to know about logical router gateway ports for
+     * NAT/LB on a distributed router.  The "distributed gateway ports" are
       * populated only when there is a gateway chassis or ha chassis group
       * specified for some of the ports on the logical router. Otherwise this
       * will be NULL. */
@@ -761,16 +761,6 @@ init_nat_entries(struct ovn_datapath *od)
          return;
      }
- if (od->n_l3dgw_ports > 1) {
-        static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 1);
-        VLOG_WARN_RL(&rl, "NAT is configured on logical router %s, which has %"
-                     PRIuSIZE" distributed gateway ports. NAT is not supported"
-                     " yet when there is more than one distributed gateway "
-                     "port on the router.",
-                     od->nbr->name, od->n_l3dgw_ports);
-        return;
-    }
-
      od->nat_entries = xmalloc(od->nbr->n_nat * sizeof *od->nat_entries);
for (size_t i = 0; i < od->nbr->n_nat; i++) {
@@ -2704,8 +2694,9 @@ join_logical_ports(struct northd_input *input_data,
   * by one or more IP addresses, and if the port is a distributed gateway
   * port, followed by 'is_chassis_resident("LPORT_NAME")', where the
   * LPORT_NAME is the name of the L3 redirect port or the name of the
- * logical_port specified in a NAT rule.  These strings include the
- * external IP addresses of all NAT rules defined on that router, and all
+ * logical_port specified in a NAT rule. These strings include the
+ * external IP addresses of NAT rules defined on that router which have
+ * gateway_port not set or have gateway_port as the router port 'op', and all
   * of the IP addresses used in load balancer VIPs defined on that router.
   *
   * The caller must free each of the n returned strings with free(),
@@ -2718,8 +2709,7 @@ get_nat_addresses(const struct ovn_port *op, size_t *n, 
bool routable_only,
      struct eth_addr mac;
      if (!op || !op->nbrp || !op->od || !op->od->nbr
          || (!op->od->nbr->n_nat && !op->od->has_lb_vip)
-        || !eth_addr_from_string(op->nbrp->mac, &mac)
-        || op->od->n_l3dgw_ports > 1) {
+        || !eth_addr_from_string(op->nbrp->mac, &mac)) {
          *n = n_nats;
          return NULL;
      }
@@ -2748,6 +2738,12 @@ get_nat_addresses(const struct ovn_port *op, size_t *n, 
bool routable_only,
              continue;
          }
+ /* Not including external IP of NAT rules whose gateway_port is
+         * not 'op'. */
+        if (nat->gateway_port && nat->gateway_port != op->nbrp) {
+            continue;
+        }
+
          /* Determine whether this NAT rule satisfies the conditions for
           * distributed NAT processing. */
          if (op->od->n_l3dgw_ports && !strcmp(nat->type, "dnat_and_snat")
@@ -2818,9 +2814,9 @@ get_nat_addresses(const struct ovn_port *op, size_t *n, 
bool routable_only,
      if (central_ip_address) {
          /* Gratuitous ARP for centralized NAT rules on distributed gateway
           * ports should be restricted to the gateway chassis. */
-        if (op->od->n_l3dgw_ports) {
+        if (is_l3dgw_port(op)) {
              ds_put_format(&c_addresses, " is_chassis_resident(%s)",
-                          op->od->l3dgw_ports[0]->cr_port->json_key);
+                          op->cr_port->json_key);
          }
addresses[n_nats++] = ds_steal_cstr(&c_addresses);
@@ -3453,9 +3449,12 @@ ovn_port_update_sbrec(struct northd_input *input_data,
                  }
if (op->peer->od->n_l3dgw_ports) {
+                    const struct ovn_port *l3dgw_port = (
+                        is_l3dgw_port(op->peer)
+                        ? op->peer
+                        : op->peer->od->l3dgw_ports[0]);
                      ds_put_format(&garp_info, " is_chassis_resident(%s)",
-                                  op->peer->od->l3dgw_ports[0]
-                                  ->cr_port->json_key);
+                                  l3dgw_port->cr_port->json_key);
                  }
n_nats++;
@@ -10278,6 +10277,12 @@ build_lrouter_port_nat_arp_nd_flow(struct ovn_port *op,
      const struct nbrec_nat *nat = nat_entry->nb;
      struct ds match = DS_EMPTY_INITIALIZER;
+ /* ARP/ND should be sent from distributed gateway port specified in
+     * the NAT rule. */
+    if (nat->gateway_port && nat->gateway_port != op->nbrp) {
+        return;
+    }
+
      /* Mac address to use when replying to ARP/NS. */
      const char *mac_s = REG_INPORT_ETH_ADDR;
      struct eth_addr mac;
@@ -10301,10 +10306,9 @@ build_lrouter_port_nat_arp_nd_flow(struct ovn_port *op,
           * upstream MAC learning points to the gateway chassis.
           * Also need to avoid generation of multiple ARP responses
           * from different chassis. */
-        if (op->od->n_l3dgw_ports) {
-            ds_put_format(&match, "is_chassis_resident(%s)",
-                          op->od->l3dgw_ports[0]->cr_port->json_key);
-        }
+        ovs_assert(is_l3dgw_port(op));
+        ds_put_format(&match, "is_chassis_resident(%s)",
+                      op->cr_port->json_key);
      }
/* Respond to ARP/NS requests on the chassis that binds the gw
@@ -12007,7 +12011,7 @@ build_ipv6_input_flows_for_lrouter_port(
          struct ds *match, struct ds *actions,
          const struct shash *meter_groups)
  {
-    if (op->nbrp && (!op->l3dgw_port)) {
+    if (op->nbrp && !is_cr_port(op)) {
          /* No ingress packets are accepted on a chassisredirect
           * port, so no need to program flows for that port. */
          if (op->lrp_networks.n_ipv6_addrs) {
@@ -12136,7 +12140,7 @@ build_ipv6_input_flows_for_lrouter_port(
              ds_clear(match);
              ds_clear(actions);
              ds_clear(&ip_ds);
-            if (op->od->n_l3dgw_ports && op->od->l3dgw_ports[0] == op) {
+            if (is_l3dgw_port(op)) {
                  ds_put_cstr(&ip_ds, "ip6.dst <-> ip6.src");
              } else {
                  ds_put_format(&ip_ds, "ip6.dst = ip6.src; ip6.src = %s",
@@ -12226,7 +12230,7 @@ build_lrouter_ipv4_ip_input(struct ovn_port *op,
  {
      /* No ingress packets are accepted on a chassisredirect
       * port, so no need to program flows for that port. */
-    if (op->nbrp && (!op->l3dgw_port)) {
+    if (op->nbrp && !is_cr_port(op)) {
          if (op->lrp_networks.n_ipv4_addrs) {
              /* L3 admission control: drop packets that originate from an
               * IPv4 address owned by the router or a broadcast address
@@ -12268,7 +12272,7 @@ build_lrouter_ipv4_ip_input(struct ovn_port *op,
              ds_clear(match);
              ds_clear(actions);
              ds_clear(&ip_ds);
-            if (op->od->n_l3dgw_ports && op->od->l3dgw_ports[0] == op) {
+            if (is_l3dgw_port(op)) {
                  ds_put_cstr(&ip_ds, "ip4.dst <-> ip4.src");
              } else {
                  ds_put_format(&ip_ds, "ip4.dst = ip4.src; ip4.src = %s",
@@ -12513,7 +12517,8 @@ build_lrouter_ipv4_ip_input(struct ovn_port *op,
  static void
  build_lrouter_in_unsnat_flow(struct hmap *lflows, struct ovn_datapath *od,
                               const struct nbrec_nat *nat, struct ds *match,
-                             struct ds *actions, bool distributed, bool is_v6)
+                             struct ds *actions, bool distributed, bool is_v6,
+                             struct ovn_port *l3dgw_port)
  {
      /* Ingress UNSNAT table: It is for already established connections'
      * reverse traffic. i.e., SNAT has already been done in egress
@@ -12552,12 +12557,12 @@ build_lrouter_in_unsnat_flow(struct hmap *lflows, 
struct ovn_datapath *od,
          ds_clear(actions);
          ds_put_format(match, "ip && ip%s.dst == %s && inport == %s && "
                        "flags.loopback == 0", is_v6 ? "6" : "4",
-                      nat->external_ip, od->l3dgw_ports[0]->json_key);
+                      nat->external_ip, l3dgw_port->json_key);
          if (!distributed && od->n_l3dgw_ports) {
              /* Flows for NAT rules that are centralized are only
              * programmed on the gateway chassis. */
              ds_put_format(match, " && is_chassis_resident(%s)",
-                          od->l3dgw_ports[0]->cr_port->json_key);
+                          l3dgw_port->cr_port->json_key);
          }
if (!strcmp(nat->type, "dnat_and_snat") && stateless) {
@@ -12577,12 +12582,12 @@ build_lrouter_in_unsnat_flow(struct hmap *lflows, 
struct ovn_datapath *od,
              ds_put_format(match, "ip && ip%s.dst == %s && inport == %s && "
                            "flags.loopback == 1 && flags.use_snat_zone == 1",
                            is_v6 ? "6" : "4", nat->external_ip,
-                          od->l3dgw_ports[0]->json_key);
+                          l3dgw_port->json_key);
              if (!distributed && od->n_l3dgw_ports) {
                  /* Flows for NAT rules that are centralized are only
                  * programmed on the gateway chassis. */
                  ds_put_format(match, " && is_chassis_resident(%s)",
-                            od->l3dgw_ports[0]->cr_port->json_key);
+                            l3dgw_port->cr_port->json_key);
              }
              ds_put_cstr(actions, "ct_snat;");
              ovn_lflow_add_with_hint(lflows, od, S_ROUTER_IN_UNSNAT,
@@ -12596,7 +12601,8 @@ static void
  build_lrouter_in_dnat_flow(struct hmap *lflows, struct ovn_datapath *od,
                             const struct nbrec_nat *nat, struct ds *match,
                             struct ds *actions, bool distributed,
-                           ovs_be32 mask, bool is_v6)
+                           ovs_be32 mask, bool is_v6,
+                           struct ovn_port *l3dgw_port)
  {
      /* Ingress DNAT table: Packets enter the pipeline with destination
      * IP address that needs to be DNATted from a external IP address
@@ -12648,12 +12654,12 @@ build_lrouter_in_dnat_flow(struct hmap *lflows, 
struct ovn_datapath *od,
              ds_clear(match);
              ds_put_format(match, "ip && ip%s.dst == %s && inport == %s",
                            is_v6 ? "6" : "4", nat->external_ip,
-                          od->l3dgw_ports[0]->json_key);
+                          l3dgw_port->json_key);
              if (!distributed && od->n_l3dgw_ports) {
                  /* Flows for NAT rules that are centralized are only
                  * programmed on the gateway chassis. */
                  ds_put_format(match, " && is_chassis_resident(%s)",
-                              od->l3dgw_ports[0]->cr_port->json_key);
+                              l3dgw_port->cr_port->json_key);
              }
              ds_clear(actions);
              if (nat->allowed_ext_ips || nat->exempted_ext_ips) {
@@ -12683,7 +12689,8 @@ static void
  build_lrouter_out_undnat_flow(struct hmap *lflows, struct ovn_datapath *od,
                                const struct nbrec_nat *nat, struct ds *match,
                                struct ds *actions, bool distributed,
-                              struct eth_addr mac, bool is_v6)
+                              struct eth_addr mac, bool is_v6,
+                              struct ovn_port *l3dgw_port)
  {
      /* Egress UNDNAT table: It is for already established connections'
      * reverse traffic. i.e., DNAT has already been done in ingress
@@ -12700,12 +12707,12 @@ build_lrouter_out_undnat_flow(struct hmap *lflows, 
struct ovn_datapath *od,
      ds_clear(match);
      ds_put_format(match, "ip && ip%s.src == %s && outport == %s",
                    is_v6 ? "6" : "4", nat->logical_ip,
-                  od->l3dgw_ports[0]->json_key);
+                  l3dgw_port->json_key);
      if (!distributed && od->n_l3dgw_ports) {
          /* Flows for NAT rules that are centralized are only
          * programmed on the gateway chassis. */
          ds_put_format(match, " && is_chassis_resident(%s)",
-                      od->l3dgw_ports[0]->cr_port->json_key);
+                      l3dgw_port->cr_port->json_key);
      }
      ds_clear(actions);
      if (distributed) {
@@ -12731,7 +12738,7 @@ static void
  build_lrouter_out_is_dnat_local(struct hmap *lflows, struct ovn_datapath *od,
                                  const struct nbrec_nat *nat, struct ds *match,
                                  struct ds *actions, bool distributed,
-                                bool is_v6)
+                                bool is_v6, struct ovn_port *l3dgw_port)
  {
      /* Note that this only applies for NAT on a distributed router.
       */
@@ -12746,7 +12753,7 @@ build_lrouter_out_is_dnat_local(struct hmap *lflows, 
struct ovn_datapath *od,
          ds_put_format(match, "is_chassis_resident(\"%s\")", 
nat->logical_port);
      } else {
          ds_put_format(match, "is_chassis_resident(%s)",
-                      od->l3dgw_ports[0]->cr_port->json_key);
+                      l3dgw_port->cr_port->json_key);
      }
ds_clear(actions);
@@ -12762,7 +12769,8 @@ build_lrouter_out_snat_flow(struct hmap *lflows, struct 
ovn_datapath *od,
                              const struct nbrec_nat *nat, struct ds *match,
                              struct ds *actions, bool distributed,
                              struct eth_addr mac, ovs_be32 mask,
-                            int cidr_bits, bool is_v6)
+                            int cidr_bits, bool is_v6,
+                            struct ovn_port *l3dgw_port)
  {
      /* Egress SNAT table: Packets enter the egress pipeline with
      * source ip address that needs to be SNATted to a external ip
@@ -12809,7 +12817,7 @@ build_lrouter_out_snat_flow(struct hmap *lflows, struct 
ovn_datapath *od,
          ds_clear(match);
          ds_put_format(match, "ip && ip%s.src == %s && outport == %s",
                        is_v6 ? "6" : "4", nat->logical_ip,
-                      od->l3dgw_ports[0]->json_key);
+                      l3dgw_port->json_key);
          if (od->n_l3dgw_ports) {
              if (distributed) {
                  ovs_assert(nat->logical_port);
@@ -12821,7 +12829,7 @@ build_lrouter_out_snat_flow(struct hmap *lflows, struct 
ovn_datapath *od,
                  * programmed on the gateway chassis. */
                  priority += 128;
                  ds_put_format(match, " && is_chassis_resident(%s)",
-                              od->l3dgw_ports[0]->cr_port->json_key);
+                              l3dgw_port->cr_port->json_key);
              }
          }
          ds_clear(actions);
@@ -12880,13 +12888,13 @@ build_lrouter_ingress_nat_check_pkt_len(struct hmap 
*lflows,
                                          const struct nbrec_nat *nat,
                                          struct ovn_datapath *od, bool is_v6,
                                          struct ds *match, struct ds *actions,
-                                        int mtu,
+                                        int mtu, struct ovn_port *l3dgw_port,
                                          const struct shash *meter_groups)
  {
          ds_clear(match);
          ds_put_format(match, "inport == %s && "REGBIT_PKT_LARGER
                        " && "REGBIT_EGRESS_LOOPBACK" == 0",
-                      od->l3dgw_ports[0]->json_key);
+                      l3dgw_port->json_key);
ds_clear(actions);
          if (!is_v6) {
@@ -12907,7 +12915,7 @@ build_lrouter_ingress_nat_check_pkt_len(struct hmap 
*lflows,
                  "outport = %s; flags.loopback = 1; output; };",
                  nat->external_mac,
                  nat->external_ip,
-                mtu, od->l3dgw_ports[0]->json_key);
+                mtu, l3dgw_port->json_key);
              ovn_lflow_add_with_hint__(lflows, od, S_ROUTER_IN_IP_INPUT, 160,
                                        ds_cstr(match), ds_cstr(actions),
                                        NULL,
@@ -12934,7 +12942,7 @@ build_lrouter_ingress_nat_check_pkt_len(struct hmap 
*lflows,
                  "outport = %s; flags.loopback = 1; output; };",
                  nat->external_mac,
                  nat->external_ip,
-                mtu, od->l3dgw_ports[0]->json_key);
+                mtu, l3dgw_port->json_key);
              ovn_lflow_add_with_hint__(lflows, od, S_ROUTER_IN_IP_INPUT, 160,
                                        ds_cstr(match), ds_cstr(actions),
                                        NULL,
@@ -12951,13 +12959,14 @@ build_lrouter_ingress_flow(struct hmap *lflows, 
struct ovn_datapath *od,
                             const struct nbrec_nat *nat, struct ds *match,
                             struct ds *actions, struct eth_addr mac,
                             bool distributed, bool is_v6,
+                           struct ovn_port *l3dgw_port,
                             const struct shash *meter_groups)
  {
      if (od->n_l3dgw_ports && !strcmp(nat->type, "snat")) {
          ds_clear(match);
          ds_put_format(
              match, "inport == %s && %s == %s",
-            od->l3dgw_ports[0]->json_key,
+            l3dgw_port->json_key,
              is_v6 ? "ip6.src" : "ip4.src", nat->external_ip);
          ovn_lflow_add_with_hint(lflows, od, S_ROUTER_IN_IP_INPUT,
                                  120, ds_cstr(match), "next;",
@@ -12973,32 +12982,33 @@ build_lrouter_ingress_flow(struct hmap *lflows, 
struct ovn_datapath *od,
          * This will save us from having to match on inport further
          * down in the pipeline.
          */
-        int gw_mtu = smap_get_int(&od->l3dgw_ports[0]->nbrp->options,
+        int gw_mtu = smap_get_int(&l3dgw_port->nbrp->options,
                                    "gateway_mtu", 0);
          ds_clear(match);
          ds_put_format(match,
                        "eth.dst == "ETH_ADDR_FMT" && inport == %s"
                        " && is_chassis_resident(\"%s\")",
                        ETH_ADDR_ARGS(mac),
-                      od->l3dgw_ports[0]->json_key,
+                      l3dgw_port->json_key,
                        nat->logical_port);
-        build_gateway_mtu_flow(lflows, od->l3dgw_ports[0],
+        build_gateway_mtu_flow(lflows, l3dgw_port,
                                 S_ROUTER_IN_ADMISSION, 50, 55,
                                 match, actions, &nat->header_,
                                 REG_INPORT_ETH_ADDR " = %s; next;",
-                               od->l3dgw_ports[0]->lrp_networks.ea_s);
+                               l3dgw_port->lrp_networks.ea_s);
          if (gw_mtu) {
              build_lrouter_ingress_nat_check_pkt_len(lflows, nat, od, is_v6,
                                                      match, actions, gw_mtu,
-                                                    meter_groups);
+                                                    l3dgw_port, meter_groups);
          }
      }
  }
static int
  lrouter_check_nat_entry(struct ovn_datapath *od, const struct nbrec_nat *nat,
-                        ovs_be32 *mask, bool *is_v6, int *cidr_bits,
-                        struct eth_addr *mac, bool *distributed)
+                        const struct hmap *ports, ovs_be32 *mask,
+                        bool *is_v6, int *cidr_bits, struct eth_addr *mac,
+                        bool *distributed, struct ovn_port **nat_l3dgw_port)
  {
      struct in6_addr ipv6, mask_v6, v6_exact = IN6ADDR_EXACT_INIT;
      ovs_be32 ip;
@@ -13032,6 +13042,32 @@ lrouter_check_nat_entry(struct ovn_datapath *od, const 
struct nbrec_nat *nat,
          *is_v6 = true;
      }
+ /* Validate gateway_port of NAT rule. */
+    *nat_l3dgw_port = NULL;
+    if (nat->gateway_port == NULL) {
+        if (od->n_l3dgw_ports > 1) {
+            static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 1);
+            VLOG_WARN_RL(&rl, "NAT configured on logical router: %s with"
+                         "multiple distributed gateway ports needs to specify"
+                         "valid gateway_port.", od->nbr->name);
+            return -EINVAL;
+        } else if (od->n_l3dgw_ports) {
+            *nat_l3dgw_port = od->l3dgw_ports[0];
+        }
+    } else {
+        *nat_l3dgw_port = ovn_port_find(ports, nat->gateway_port->name);
+
+        if (!(*nat_l3dgw_port) || (*nat_l3dgw_port)->od != od ||
+            !is_l3dgw_port(*nat_l3dgw_port)) {
+            static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 1);
+            VLOG_WARN_RL(&rl, "gateway_port: %s of NAT configured on "
+                         "logical router: %s is not a valid distributed "
+                         "gateway port on that router",
+                         nat->gateway_port->name, od->nbr->name);
+            return -EINVAL;
+        }
+    }
+
      /* Check the validity of nat->logical_ip. 'logical_ip' can
      * be a subnet when the type is "snat". */
      if (*is_v6) {
@@ -13131,7 +13167,7 @@ build_lrouter_nat_defrag_and_lb(struct ovn_datapath 
*od, struct hmap *lflows,
      ovn_lflow_add(lflows, od, S_ROUTER_OUT_SNAT, 120, "nd_ns", "next;");
/* NAT rules are only valid on Gateway routers and routers with
-     * l3dgw_port (router has a port with gateway chassis
+     * l3dgw_ports (router has port(s) with gateway chassis
       * specified). */
      if (!od->is_gw_router && !od->n_l3dgw_ports) {
          return;
@@ -13150,18 +13186,19 @@ build_lrouter_nat_defrag_and_lb(struct ovn_datapath 
*od, struct hmap *lflows,
          bool is_v6, distributed;
          ovs_be32 mask;
          int cidr_bits;
+        struct ovn_port *l3dgw_port;
- if (lrouter_check_nat_entry(od, nat, &mask, &is_v6, &cidr_bits,
-                                    &mac, &distributed) < 0) {
+        if (lrouter_check_nat_entry(od, nat, ports, &mask, &is_v6, &cidr_bits,
+                                    &mac, &distributed, &l3dgw_port) < 0) {
              continue;
          }
/* S_ROUTER_IN_UNSNAT */
          build_lrouter_in_unsnat_flow(lflows, od, nat, match, actions, 
distributed,
-                                     is_v6);
+                                     is_v6, l3dgw_port);
          /* S_ROUTER_IN_DNAT */
          build_lrouter_in_dnat_flow(lflows, od, nat, match, actions, 
distributed,
-                                   mask, is_v6);
+                                   mask, is_v6, l3dgw_port);
/* ARP resolve for NAT IPs. */
          if (od->is_gw_router) {
@@ -13174,14 +13211,14 @@ build_lrouter_nat_defrag_and_lb(struct ovn_datapath 
*od, struct hmap *lflows,
                  ds_clear(match);
                  ds_put_format(
                      match, "outport == %s && %s == %s",
-                    od->l3dgw_ports[0]->json_key,
+                    l3dgw_port->json_key,
                      is_v6 ? REG_NEXT_HOP_IPV6 : REG_NEXT_HOP_IPV4,
                      nat->external_ip);
                  ds_clear(actions);
                  ds_put_format(
                      actions, "eth.dst = %s; next;",
                      distributed ? nat->external_mac :
-                    od->l3dgw_ports[0]->lrp_networks.ea_s);
+                    l3dgw_port->lrp_networks.ea_s);
                  ovn_lflow_add_with_hint(lflows, od,
                                          S_ROUTER_IN_ARP_RESOLVE,
                                          100, ds_cstr(match),
@@ -13193,18 +13230,19 @@ build_lrouter_nat_defrag_and_lb(struct ovn_datapath 
*od, struct hmap *lflows,
/* S_ROUTER_OUT_DNAT_LOCAL */
          build_lrouter_out_is_dnat_local(lflows, od, nat, match, actions,
-                                        distributed, is_v6);
+                                        distributed, is_v6, l3dgw_port);
/* S_ROUTER_OUT_UNDNAT */
          build_lrouter_out_undnat_flow(lflows, od, nat, match, actions, 
distributed,
-                                      mac, is_v6);
+                                      mac, is_v6, l3dgw_port);
          /* S_ROUTER_OUT_SNAT */
          build_lrouter_out_snat_flow(lflows, od, nat, match, actions, 
distributed,
-                                    mac, mask, cidr_bits, is_v6);
+                                    mac, mask, cidr_bits, is_v6, l3dgw_port);
/* S_ROUTER_IN_ADMISSION - S_ROUTER_IN_IP_INPUT */
-        build_lrouter_ingress_flow(lflows, od, nat, match, actions,
-                                   mac, distributed, is_v6, meter_groups);
+        build_lrouter_ingress_flow(lflows, od, nat, match, actions, mac,
+                                   distributed, is_v6, l3dgw_port,
+                                   meter_groups);
/* Ingress Gateway Redirect Table: For NAT on a distributed
           * router, add flows that are specific to a NAT rule.  These
@@ -13221,7 +13259,7 @@ build_lrouter_nat_defrag_and_lb(struct ovn_datapath 
*od, struct hmap *lflows,
              ds_put_format(match,
                            "ip%s.src == %s && outport == %s",
                            is_v6 ? "6" : "4", nat->logical_ip,
-                          od->l3dgw_ports[0]->json_key);
+                          l3dgw_port->json_key);
              /* Add a rule to drop traffic from a distributed NAT if
               * the virtual port has not claimed yet becaused otherwise
               * the traffic will be centralized misconfiguring the TOR switch.
@@ -13254,10 +13292,10 @@ build_lrouter_nat_defrag_and_lb(struct ovn_datapath 
*od, struct hmap *lflows,
              ds_put_format(match, "ip%s.dst == %s && outport == %s",
                            is_v6 ? "6" : "4",
                            nat->external_ip,
-                          od->l3dgw_ports[0]->json_key);
+                          l3dgw_port->json_key);
              if (!distributed) {
                  ds_put_format(match, " && is_chassis_resident(%s)",
-                              od->l3dgw_ports[0]->cr_port->json_key);
+                              l3dgw_port->cr_port->json_key);
              } else {
                  ds_put_format(match, " && is_chassis_resident(\"%s\")",
                                nat->logical_port);
diff --git a/northd/ovn-northd.8.xml b/northd/ovn-northd.8.xml
index e495db46a..6adec765b 100644
--- a/northd/ovn-northd.8.xml
+++ b/northd/ovn-northd.8.xml
@@ -2943,7 +2943,8 @@ icmp6 {
                <code>ip &amp;&amp;
                ip6.dst == <var>B</var> &amp;&amp; inport == <var>GW</var>
                &amp;&amp; flags.loopback == 0</code>
-              where <var>GW</var> is the logical router gateway port, with an
+              where <var>GW</var> is the distributed gateway port
+              specified in the NAT rule, with an
                action <code>ct_snat_in_czone;</code> to unSNAT in the common
                zone.  If the NAT rule is of type dnat_and_snat and has
                <code>stateless=true</code> in the options, then the action
@@ -2968,7 +2969,8 @@ icmp6 {
                ip6.dst == <var>B</var> &amp;&amp; inport == <var>GW</var>
                &amp;&amp; flags.loopback == 0 &amp;&amp;
                flags.use_snat_zone == 1</code>
-              where <var>GW</var> is the logical router gateway port, with an
+              where <var>GW</var> is the distributed gateway port
+              specified in the NAT rule, with an
                action <code>ct_snat;</code> to unSNAT in the snat zone. If the
                NAT rule is of type dnat_and_snat and has
                <code>stateless=true</code> in the options, then the action
@@ -3249,9 +3251,10 @@ icmp6 {
            to change the destination IP address of a packet from <var>A</var> 
to
            <var>B</var>, a priority-100 flow matches <code>ip &amp;&amp;
            ip4.dst == <var>B</var> &amp;&amp; inport == <var>GW</var></code>,
-          where <var>GW</var> is the logical router gateway port, with an
-          action <code>ct_dnat(<var>B</var>);</code>.  The match will
-          include <code>ip6.dst == <var>B</var></code> in the IPv6 case.
+          where <var>GW</var> is the logical router gateway port configured
+          for the NAT rule, with an action
+          <code>ct_dnat(<var>B</var>);</code>.  The match will include
+          <code>ip6.dst == <var>B</var></code> in the IPv6 case.
            If the NAT rule is of type dnat_and_snat and has
            <code>stateless=true</code> in the options, then the action
            would be <code>ip4/6.dst=(<var>B</var>)</code>.
@@ -4061,10 +4064,11 @@ icmp6 {
          flow with match <code>ip4.src == <var>B</var> &amp;&amp;
          outport == <var>GW</var></code> &amp;&amp;
          is_chassis_resident(<var>P</var>), where <var>GW</var> is
-        the logical router distributed gateway port and <var>P</var>
-        is the NAT logical port. IP traffic matching the above rule
-        will be managed locally setting <code>reg1</code> to <var>C</var>
-        and <code>eth.src</code> to <var>D</var>, where <var>C</var> is NAT
+        the distributed gateway port specified in the
+        NAT rule and <var>P</var> is the NAT logical port. IP traffic
+        matching the above rule will be managed locally setting
+        <code>reg1</code> to <var>C</var> and
+        <code>eth.src</code> to <var>D</var>, where <var>C</var> is NAT
          external ip and <var>D</var> is NAT external mac.
        </li>
@@ -4531,8 +4535,9 @@ nd_ns {
            outport == <var>GW</var> &amp;&amp;
            is_chassis_resident(<var>P</var>)</code>, where <var>E</var> is the
            external IP address specified in the NAT rule, <var>GW</var>
-          is the logical router distributed gateway port. For dnat_and_snat
-          NAT rule, <var>P</var> is the logical port specified in the NAT rule.
+          is the distributed gateway port specified in the NAT rule.
+          For dnat_and_snat NAT rule, <var>P</var> is the logical port
+          specified in the NAT rule.
            If <ref column="logical_port"
            table="NAT" db="OVN_Northbound"/> column of
            <ref table="NAT" db="OVN_Northbound"/> table is NOT set, then
diff --git a/ovn-architecture.7.xml b/ovn-architecture.7.xml
index ef8d669a2..a48757761 100644
--- a/ovn-architecture.7.xml
+++ b/ovn-architecture.7.xml
@@ -742,9 +742,9 @@
<p>
      A logical router can have multiple distributed gateway ports, each
-    connecting different external networks. However, some features, such as NAT
-    and load balancers, are not supported yet for logical routers with more
-    than one distributed gateway port configured.
+    connecting different external networks. Load balancing is not yet
+    supported for logical routers with more than one distributed gateway
+    port configured.
    </p>
<h4>Physical VLAN MTU Issues</h4>
diff --git a/ovn-nb.ovsschema b/ovn-nb.ovsschema
index 80b830629..1a342c473 100644
--- a/ovn-nb.ovsschema
+++ b/ovn-nb.ovsschema
@@ -1,7 +1,7 @@
  {
      "name": "OVN_Northbound",
-    "version": "6.1.0",
-    "cksum": "4010776751 31237",
+    "version": "6.2.0",
+    "cksum": "3707848838 31535",
      "tables": {
          "NB_Global": {
              "columns": {
@@ -479,6 +479,12 @@
                              "refType": "strong"},
                      "min": 0,
                      "max": 1}},
+                "gateway_port": {
+                    "type": {"key": {"type": "uuid",
+                                     "refTable": "Logical_Router_Port",
+                                     "refType": "strong"},
+                             "min": 0,
+                             "max": 1}},
                  "options": {"type": {"key": "string", "value": "string",
                                       "min": 0, "max": "unlimited"}},
                  "external_ids": {
diff --git a/ovn-nb.xml b/ovn-nb.xml
index beb3ded79..fc2b917ac 100644
--- a/ovn-nb.xml
+++ b/ovn-nb.xml
@@ -2590,8 +2590,8 @@
        <p>
          There can be more than one distributed gateway ports configured
          on each logical router, each connecting to different L2 segments.
-        However, features such as NAT and load-balancer are not supported
-        on logical routers with more than one distributed gateway ports.
+        Load-balancing is not yet supported on logical routers with more
+        than one distributed gateway ports.
        </p>
<p>
@@ -3323,6 +3323,39 @@
        </p>
      </column>
+ <column name="gateway_port">
+      <p>
+        A distributed gateway port in the <ref table="Logical_Router_Port"/>
+        table where the NAT rule needs to be applied.
+      </p>
+
+      <p>
+        This column needs to be set when multiple distributed gateway ports
+        are configured on a <ref table="Logical_Router"/> for the NAT rule to
+        be applied. If logical router has a single distributed gateway port,
+        NAT rule is applied at the distributed gateway port even if this
+        column is not set.
+      </p>
+
+      <p>
+        When multiple distributed gateway ports are configured on a
+        <ref table="Logical_Router"/>, applying a NAT rule at each of the
+        distributed gateway ports might not be desired. Consider the case
+        where a logical router has 2 distributed gateway port, one with
+        <ref column="networks" table="Logical_Router_Port"/>
+        <code>50.0.0.10/24</code> and the other with
+        <ref column="networks" table="Logical_Router_Port"/>
+        <code>60.0.0.10/24</code>. If the logical router has a
+        NAT rule of <ref column="type"/> <code>snat</code>,
+        <ref column="logical_ip"/> <code>10.1.1.0/24</code> and
+        <ref column="external_ip"/> <code>50.1.1.20/24</code>, the rule needs
+        to be selectively applied on matching packets entering/leaving
+        through the distributed gateway port with
+        <ref column="networks" table="Logical_Router_Port"/>
+        <code>50.0.0.10/24</code>.
+      </p>
+    </column>
+
      <column name="options" key="stateless">
        Indicates if a dnat_and_snat rule should lead to connection
        tracking state or not.
diff --git a/tests/ovn-nbctl.at b/tests/ovn-nbctl.at
index 539a121c0..b4acb2da6 100644
--- a/tests/ovn-nbctl.at
+++ b/tests/ovn-nbctl.at
@@ -510,64 +510,64 @@ AT_CHECK([ovn-nbctl lr-nat-add lr0 dnat_and_snat fd01::1 
fd11::2])
  AT_CHECK([ovn-nbctl lr-nat-add lr0 dnat_and_snat 30.0.0.2 192.168.1.3 lp0 
00:00:00:01:02:03])
  AT_CHECK([ovn-nbctl lr-nat-add lr0 dnat_and_snat fd01::2 fd11::3 lp0 
00:00:00:01:02:03])
  AT_CHECK([ovn-nbctl lr-nat-list lr0], [0], [dnl
-TYPE             EXTERNAL_IP        EXTERNAL_PORT    LOGICAL_IP            
EXTERNAL_MAC         LOGICAL_PORT
-dnat             30.0.0.1                            192.168.1.2
-dnat             fd01::1                             fd11::2
-dnat_and_snat    30.0.0.1                            192.168.1.2
-dnat_and_snat    30.0.0.2                            192.168.1.3           
00:00:00:01:02:03    lp0
-dnat_and_snat    fd01::1                             fd11::2
-dnat_and_snat    fd01::2                             fd11::3               
00:00:00:01:02:03    lp0
-snat             30.0.0.1                            192.168.1.0/24
-snat             fd01::1                             fd11::/64
+TYPE             GATEWAY_PORT          EXTERNAL_IP        EXTERNAL_PORT    
LOGICAL_IP          EXTERNAL_MAC         LOGICAL_PORT
+dnat                                   30.0.0.1                            
192.168.1.2
+dnat                                   fd01::1                             
fd11::2
+dnat_and_snat                          30.0.0.1                            
192.168.1.2
+dnat_and_snat                          30.0.0.2                            
192.168.1.3         00:00:00:01:02:03    lp0
+dnat_and_snat                          fd01::1                             
fd11::2
+dnat_and_snat                          fd01::2                             
fd11::3             00:00:00:01:02:03    lp0
+snat                                   30.0.0.1                            
192.168.1.0/24
+snat                                   fd01::1                             
fd11::/64
  ])
  AT_CHECK([ovn-nbctl lr-nat-add lr0 snat 30.0.0.1 192.168.1.0/24], [1], [],
-[ovn-nbctl: 30.0.0.1, 192.168.1.0/24: a NAT with this external_ip and 
logical_ip already exists
+[ovn-nbctl: 30.0.0.1, 192.168.1.0/24, : a NAT with this external_ip, 
logical_ip and gateway_port already exists
  ])
  AT_CHECK([ovn-nbctl lr-nat-add lr0 snat 30.0.0.1 192.168.1.10/24], [1], [],
-[ovn-nbctl: 30.0.0.1, 192.168.1.0/24: a NAT with this external_ip and 
logical_ip already exists
+[ovn-nbctl: 30.0.0.1, 192.168.1.0/24, : a NAT with this external_ip, 
logical_ip and gateway_port already exists
  ])
  AT_CHECK([ovn-nbctl --may-exist lr-nat-add lr0 snat 30.0.0.1 192.168.1.0/24])
  AT_CHECK([ovn-nbctl lr-nat-add lr0 snat 30.0.0.2 192.168.1.0/24], [1], [],
-[ovn-nbctl: a NAT with this type (snat) and logical_ip (192.168.1.0/24) 
already exists
+[ovn-nbctl: a NAT with this type (snat), logical_ip (192.168.1.0/24) and 
gateway_port () already exists
  ])
  AT_CHECK([ovn-nbctl lr-nat-add lr0 dnat 30.0.0.1 192.168.1.2], [1], [],
-[ovn-nbctl: 30.0.0.1, 192.168.1.2: a NAT with this external_ip and logical_ip 
already exists
+[ovn-nbctl: 30.0.0.1, 192.168.1.2, : a NAT with this external_ip, logical_ip 
and gateway_port already exists
  ])
  AT_CHECK([ovn-nbctl --may-exist lr-nat-add lr0 dnat 30.0.0.1 192.168.1.2])
  AT_CHECK([ovn-nbctl lr-nat-add lr0 dnat 30.0.0.1 192.168.1.3], [1], [],
-[ovn-nbctl: a NAT with this type (dnat) and external_ip (30.0.0.1) already 
exists
+[ovn-nbctl: a NAT with this type (dnat), external_ip (30.0.0.1) and 
gateway_port () already exists
  ])
  AT_CHECK([ovn-nbctl lr-nat-add lr0 dnat_and_snat 30.0.0.1 192.168.1.2], [1], 
[],
-[ovn-nbctl: 30.0.0.1, 192.168.1.2: a NAT with this external_ip and logical_ip 
already exists
+[ovn-nbctl: 30.0.0.1, 192.168.1.2, : a NAT with this external_ip, logical_ip 
and gateway_port already exists
  ])
  AT_CHECK([ovn-nbctl --may-exist lr-nat-add lr0 dnat_and_snat 30.0.0.1 
192.168.1.2])
  AT_CHECK([ovn-nbctl lr-nat-add lr0 dnat_and_snat 30.0.0.1 192.168.1.3], [1], 
[],
-[ovn-nbctl: a NAT with this type (dnat_and_snat) and external_ip (30.0.0.1) 
already exists
+[ovn-nbctl: a NAT with this type (dnat_and_snat), external_ip (30.0.0.1) and 
gateway_port () already exists
  ])
  AT_CHECK([ovn-nbctl --may-exist lr-nat-add lr0 dnat_and_snat 30.0.0.2 
192.168.1.3 lp0 00:00:00:04:05:06])
  AT_CHECK([ovn-nbctl lr-nat-list lr0], [0], [dnl
-TYPE             EXTERNAL_IP        EXTERNAL_PORT    LOGICAL_IP            
EXTERNAL_MAC         LOGICAL_PORT
-dnat             30.0.0.1                            192.168.1.2
-dnat             fd01::1                             fd11::2
-dnat_and_snat    30.0.0.1                            192.168.1.2
-dnat_and_snat    30.0.0.2                            192.168.1.3           
00:00:00:04:05:06    lp0
-dnat_and_snat    fd01::1                             fd11::2
-dnat_and_snat    fd01::2                             fd11::3               
00:00:00:01:02:03    lp0
-snat             30.0.0.1                            192.168.1.0/24
-snat             fd01::1                             fd11::/64
+TYPE             GATEWAY_PORT          EXTERNAL_IP        EXTERNAL_PORT    
LOGICAL_IP          EXTERNAL_MAC         LOGICAL_PORT
+dnat                                   30.0.0.1                            
192.168.1.2
+dnat                                   fd01::1                             
fd11::2
+dnat_and_snat                          30.0.0.1                            
192.168.1.2
+dnat_and_snat                          30.0.0.2                            
192.168.1.3         00:00:00:04:05:06    lp0
+dnat_and_snat                          fd01::1                             
fd11::2
+dnat_and_snat                          fd01::2                             
fd11::3             00:00:00:01:02:03    lp0
+snat                                   30.0.0.1                            
192.168.1.0/24
+snat                                   fd01::1                             
fd11::/64
  ])
  AT_CHECK([ovn-nbctl --may-exist lr-nat-add lr0 dnat_and_snat 30.0.0.2 
192.168.1.3])
  AT_CHECK([ovn-nbctl --may-exist lr-nat-add lr0 dnat_and_snat fd01::2 fd11::3])
  AT_CHECK([ovn-nbctl lr-nat-list lr0], [0], [dnl
-TYPE             EXTERNAL_IP        EXTERNAL_PORT    LOGICAL_IP            
EXTERNAL_MAC         LOGICAL_PORT
-dnat             30.0.0.1                            192.168.1.2
-dnat             fd01::1                             fd11::2
-dnat_and_snat    30.0.0.1                            192.168.1.2
-dnat_and_snat    30.0.0.2                            192.168.1.3
-dnat_and_snat    fd01::1                             fd11::2
-dnat_and_snat    fd01::2                             fd11::3
-snat             30.0.0.1                            192.168.1.0/24
-snat             fd01::1                             fd11::/64
+TYPE             GATEWAY_PORT          EXTERNAL_IP        EXTERNAL_PORT    
LOGICAL_IP          EXTERNAL_MAC         LOGICAL_PORT
+dnat                                   30.0.0.1                            
192.168.1.2
+dnat                                   fd01::1                             
fd11::2
+dnat_and_snat                          30.0.0.1                            
192.168.1.2
+dnat_and_snat                          30.0.0.2                            
192.168.1.3
+dnat_and_snat                          fd01::1                             
fd11::2
+dnat_and_snat                          fd01::2                             
fd11::3
+snat                                   30.0.0.1                            
192.168.1.0/24
+snat                                   fd01::1                             
fd11::/64
  ])
check_row_count nb:NAT 0 options:stateless=true
@@ -598,40 +598,31 @@ AT_CHECK([ovn-nbctl --stateless lr-nat-add lr0 
dnat_and_snat 40.0.0.3 192.168.1.
  ])
dnl Deletes the NATs
-AT_CHECK([ovn-nbctl lr-nat-del lr0 dnat_and_snat 30.0.0.3], [1], [],
-[ovn-nbctl: no matching NAT with the type (dnat_and_snat) and external_ip 
(30.0.0.3)
-])
-AT_CHECK([ovn-nbctl lr-nat-del lr0 dnat 30.0.0.2], [1], [],
-[ovn-nbctl: no matching NAT with the type (dnat) and external_ip (30.0.0.2)
-])
-AT_CHECK([ovn-nbctl lr-nat-del lr0 snat 192.168.10.0/24], [1], [],
-[ovn-nbctl: no matching NAT with the type (snat) and logical_ip 
(192.168.10.0/24)
-])
-AT_CHECK([ovn-nbctl --if-exists lr-nat-del lr0 snat 192.168.10.0/24])
+AT_CHECK([ovn-nbctl lr-nat-del lr0 dnat_and_snat 30.0.0.3])

I don't understand the above change. First, I don't understand why many of the lr-nat-del checks were removed. Second, I don't understand why the lr-nat-del of 30.0.0.3 doesn't return an error. There is no NAT with that address, so shouldn't that return an error?

AT_CHECK([ovn-nbctl lr-nat-del lr0 dnat_and_snat 30.0.0.1])
  AT_CHECK([ovn-nbctl lr-nat-del lr0 dnat_and_snat fd01::1])
  AT_CHECK([ovn-nbctl lr-nat-list lr0], [0], [dnl
-TYPE             EXTERNAL_IP        EXTERNAL_PORT    LOGICAL_IP            
EXTERNAL_MAC         LOGICAL_PORT
-dnat             30.0.0.1                            192.168.1.2
-dnat             fd01::1                             fd11::2
-dnat_and_snat    30.0.0.2                            192.168.1.3
-dnat_and_snat    40.0.0.2                            192.168.1.4
-dnat_and_snat    fd01::2                             fd11::3
-snat             30.0.0.1                            192.168.1.0/24
-snat             40.0.0.3                            192.168.1.6
-snat             fd01::1                             fd11::/64
+TYPE             GATEWAY_PORT          EXTERNAL_IP        EXTERNAL_PORT    
LOGICAL_IP          EXTERNAL_MAC         LOGICAL_PORT
+dnat                                   30.0.0.1                            
192.168.1.2
+dnat                                   fd01::1                             
fd11::2
+dnat_and_snat                          30.0.0.2                            
192.168.1.3
+dnat_and_snat                          40.0.0.2                            
192.168.1.4
+dnat_and_snat                          fd01::2                             
fd11::3
+snat                                   30.0.0.1                            
192.168.1.0/24
+snat                                   40.0.0.3                            
192.168.1.6
+snat                                   fd01::1                             
fd11::/64
  ])
AT_CHECK([ovn-nbctl lr-nat-del lr0 dnat])
  AT_CHECK([ovn-nbctl lr-nat-list lr0], [0], [dnl
-TYPE             EXTERNAL_IP        EXTERNAL_PORT    LOGICAL_IP            
EXTERNAL_MAC         LOGICAL_PORT
-dnat_and_snat    30.0.0.2                            192.168.1.3
-dnat_and_snat    40.0.0.2                            192.168.1.4
-dnat_and_snat    fd01::2                             fd11::3
-snat             30.0.0.1                            192.168.1.0/24
-snat             40.0.0.3                            192.168.1.6
-snat             fd01::1                             fd11::/64
+TYPE             GATEWAY_PORT          EXTERNAL_IP        EXTERNAL_PORT    
LOGICAL_IP          EXTERNAL_MAC         LOGICAL_PORT
+dnat_and_snat                          30.0.0.2                            
192.168.1.3
+dnat_and_snat                          40.0.0.2                            
192.168.1.4
+dnat_and_snat                          fd01::2                             
fd11::3
+snat                                   30.0.0.1                            
192.168.1.0/24
+snat                                   40.0.0.3                            
192.168.1.6
+snat                                   fd01::1                             
fd11::/64
  ])
AT_CHECK([ovn-nbctl lr-nat-del lr0])
@@ -702,12 +693,12 @@ AT_CHECK([ovn-nbctl show lr0 | grep -C2 'external port(s): 
"1"' | uuidfilt], [0]
  ])
AT_CHECK([ovn-nbctl lr-nat-list lr0], [0], [dnl
-TYPE             EXTERNAL_IP        EXTERNAL_PORT    LOGICAL_IP            
EXTERNAL_MAC         LOGICAL_PORT
-dnat             40.0.0.4           1-3000           192.168.1.7
-dnat             40.0.0.5           1                192.168.1.10
-dnat_and_snat    40.0.0.5           1-3000           192.168.1.8
-dnat_and_snat    40.0.0.6           1-3000           192.168.1.9           
00:00:00:04:05:06    lp0
-snat             40.0.0.3           21-65535         192.168.1.6
+TYPE             GATEWAY_PORT          EXTERNAL_IP        EXTERNAL_PORT    
LOGICAL_IP          EXTERNAL_MAC         LOGICAL_PORT
+dnat                                   40.0.0.4           1-3000           
192.168.1.7
+dnat                                   40.0.0.5           1                
192.168.1.10
+dnat_and_snat                          40.0.0.5           1-3000           
192.168.1.8
+dnat_and_snat                          40.0.0.6           1-3000           
192.168.1.9         00:00:00:04:05:06    lp0
+snat                                   40.0.0.3           21-65535         
192.168.1.6
  ])
AT_CHECK([ovn-nbctl lr-nat-del lr0])
@@ -755,7 +746,54 @@ AT_CHECK([ovn-nbctl lr-nat-update-ext-ip lr0 snat 
192.168.16 allowed_range], [1]
  [ovn-nbctl: 192.168.16: Invalid IP address or CIDR
  ])
-AT_CHECK([ovn-nbctl lr-nat-del lr0])])
+AT_CHECK([ovn-nbctl lr-nat-del lr0])
+
+AT_CHECK([ovn-nbctl lrp-add lr0 lrp00 00:00:00:01:02:03 172.64.0.10/24])
+AT_CHECK([ovn-nbctl lrp-add lr0 lrp01 00:00:00:01:02:04 172.64.1.10/24])
+AT_CHECK([ovn-nbctl lrp-set-gateway-chassis lrp00 chassis1])
+AT_CHECK([ovn-nbctl lr-add lr1])
+AT_CHECK([ovn-nbctl lrp-add lr1 lrp10 00:00:00:01:02:05 172.64.2.10/24])
+
+AT_CHECK([ovn-nbctl --gateway-port=lrp00 lr-nat-add lr0 snat 172.64.0.10 
20.0.0.10])
+AT_CHECK([ovn-nbctl --gateway-port=lrp01 lr-nat-add lr0 dnat 172.64.1.10 
20.0.0.10], [1], [],
+[ovn-nbctl: lrp01 is not a distributed gateway router port.
+])
+AT_CHECK([ovn-nbctl --gateway-port=lrp10 lr-nat-add lr0 dnat_and_snat 
172.64.2.10 20.0.0.10], [1], [],
+[ovn-nbctl: lrp10 is not a router port of logical router: lr0.
+])
+
+AT_CHECK([ovn-nbctl lrp-set-gateway-chassis lrp01 chassis2])
+
+AT_CHECK([ovn-nbctl lr-nat-add lr0 dnat 172.64.1.10 20.0.0.10], [1], [],
+[ovn-nbctl: logical router: lr0 has multiple distributed gateway ports. NAT 
rule needs to specify gateway_port.
+])
+AT_CHECK([ovn-nbctl --gateway-port=lrp00 lr-nat-add lr0 dnat 30.0.0.10 
20.0.0.10])
+AT_CHECK([ovn-nbctl --gateway-port=lrp01 lr-nat-add lr0 dnat 30.0.0.10 
20.0.0.10])
+AT_CHECK([ovn-nbctl --gateway-port=lrp01 lr-nat-add lr0 dnat 30.0.0.10 
20.0.0.20], [1], [],
+[ovn-nbctl: a NAT with this type (dnat), external_ip (30.0.0.10) and 
gateway_port (lrp01) already exists
+])
+
+AT_CHECK([ovn-nbctl lr-nat-list lr0], [0], [dnl
+TYPE             GATEWAY_PORT          EXTERNAL_IP        EXTERNAL_PORT    
LOGICAL_IP          EXTERNAL_MAC         LOGICAL_PORT
+dnat             lrp00                 30.0.0.10                           
20.0.0.10
+dnat             lrp01                 30.0.0.10                           
20.0.0.10
+snat             lrp00                 172.64.0.10                         
20.0.0.10
+])
+
+AT_CHECK([ovn-nbctl lr-nat-del lr0 dnat 30.0.0.10])
+AT_CHECK([ovn-nbctl lr-nat-list lr0], [0], [dnl
+TYPE             GATEWAY_PORT          EXTERNAL_IP        EXTERNAL_PORT    
LOGICAL_IP          EXTERNAL_MAC         LOGICAL_PORT
+snat             lrp00                 172.64.0.10                         
20.0.0.10
+])
+AT_CHECK([ovn-nbctl lr-nat-del lr0 dnat 30.0.0.10 lrp00], [1], [],
+[ovn-nbctl: no matching NAT with the type (dnat), external_ip (30.0.0.10) and 
gateway_port (lrp00)
+])
+AT_CHECK([ovn-nbctl lr-nat-del lr0 snat 20.0.0.10 lrp01], [1], [],
+[ovn-nbctl: no matching NAT with the type (snat), logical_ip (20.0.0.10) and 
gateway_port (lrp01)
+])
+AT_CHECK([ovn-nbctl --if-exists lr-nat-del lr0 snat 20.0.0.10 lrp01])
+AT_CHECK([ovn-nbctl lr-nat-del lr0 snat 20.0.0.10 lrp00])
+])
dnl --------------------------------------------------------------------- diff --git a/tests/ovn-northd.at b/tests/ovn-northd.at
index fe2786973..166e1e0e9 100644
--- a/tests/ovn-northd.at
+++ b/tests/ovn-northd.at
@@ -4296,8 +4296,6 @@ check ovn-nbctl lsp-set-options lrp1-attachment 
router-port=lrp1
  check ovn-nbctl lr-nat-add lr0 dnat 42.42.42.42 192.168.0.2
  check ovn-nbctl --wait=sb sync
-ovn-trace --minimal 'inport == "sw1-port1" && eth.src == 50:54:00:00:00:03 && eth.dst == 00:00:00:00:ff:02 && ip4.dst == 42.42.42.42 && ip4.src == 11.0.0.2 && ip.ttl == 64'
-
  AT_CHECK([ovn-trace --minimal 'inport == "sw1-port1" && eth.src == 50:54:00:00:00:03 && eth.dst == 00:00:00:00:ff:02 
&& ip4.dst == 42.42.42.42 && ip4.src == 11.0.0.2 && ip.ttl == 64' | grep "output(\"sw0-port1\")"], [0], 
[ignore])
dnl If we remove the DNAT entry we will be unable to trace to the DNAT address
@@ -6249,3 +6247,167 @@ check_log_flows_count 0 in
AT_CLEANUP
  ])
+
+AT_SETUP([ovn-northd -- lr multiple gw ports NAT])
+AT_KEYWORDS([multiple-l3dgw-ports])
+ovn_start
+
+# Logical network:
+# 1 Logical Router, 3 bridged Logical Switches,
+# 1 gateway chassis attached to each corresponding LRP.
+#
+#                | S1 (gw1)
+#                |
+#      ls  ----  DR -- S3 (gw3)
+# (20.0.0.0/24)  |
+#                | S2 (gw2)
+#
+# Validate SNAT, DNAT and DNAT_AND_SNAT behavior with multiple
+# distributed gateway LRPs.
+
+check ovn-sbctl chassis-add gw1 geneve 127.0.0.1
+check ovn-sbctl chassis-add gw2 geneve 128.0.0.1
+check ovn-sbctl chassis-add gw3 geneve 129.0.0.1
+
+check ovn-nbctl lr-add DR
+check ovn-nbctl lrp-add DR DR-S1 02:ac:10:01:00:01 172.16.1.1/24
+check ovn-nbctl lrp-add DR DR-S2 03:ac:10:01:00:01 10.0.0.1/24
+check ovn-nbctl lrp-add DR DR-S3 04:ac:10:01:00:01 192.168.0.1/24
+check ovn-nbctl lrp-add DR DR-ls 05:ac:10:01:00:01 20.0.0.1/24
+
+check ovn-nbctl ls-add S1
+check ovn-nbctl lsp-add S1 S1-DR
+check ovn-nbctl lsp-set-type S1-DR router
+check ovn-nbctl lsp-set-addresses S1-DR router
+check ovn-nbctl --wait=sb lsp-set-options S1-DR router-port=DR-S1
+
+check ovn-nbctl ls-add S2
+check ovn-nbctl lsp-add S2 S2-DR
+check ovn-nbctl lsp-set-type S2-DR router
+check ovn-nbctl lsp-set-addresses S2-DR router
+check ovn-nbctl --wait=sb lsp-set-options S2-DR router-port=DR-S2
+
+check ovn-nbctl ls-add S3
+check ovn-nbctl lsp-add S3 S3-DR
+check ovn-nbctl lsp-set-type S3-DR router
+check ovn-nbctl lsp-set-addresses S3-DR router
+check ovn-nbctl --wait=sb lsp-set-options S3-DR router-port=DR-S3
+
+check ovn-nbctl ls-add  ls
+check ovn-nbctl lsp-add ls ls-DR
+check ovn-nbctl lsp-set-type ls-DR router
+check ovn-nbctl lsp-set-addresses ls-DR router
+check ovn-nbctl --wait=sb lsp-set-options ls-DR router-port=DR-ls
+
+check ovn-nbctl lrp-set-gateway-chassis DR-S1 gw1
+check ovn-nbctl lrp-set-gateway-chassis DR-S2 gw2
+check ovn-nbctl lrp-set-gateway-chassis DR-S3 gw3
+
+check ovn-nbctl --wait=sb sync
+
+# Configure SNAT
+check ovn-nbctl --gateway-port=DR-S1 lr-nat-add DR snat  172.16.1.10    
20.0.0.10
+check ovn-nbctl --gateway-port=DR-S2 lr-nat-add DR snat  10.0.0.10      
20.0.0.10
+check ovn-nbctl --gateway-port=DR-S3 lr-nat-add DR snat  192.168.0.10   
20.0.0.10
+
+ovn-sbctl dump-flows DR > lrflows
+AT_CAPTURE_FILE([lrflows])
+
+check_lr_in_arp_nat_flows() {
+    AT_CHECK([grep lr_in_ip_input lrflows | grep arp | grep -e 172.16.1.10 -e 
10.0.0.10 -e 192.168.0.10 | sed 's/table=../table=??/' | sort], [0], [dnl
+  table=??(lr_in_ip_input     ), priority=90   , match=(arp.op == 1 && arp.tpa == 
10.0.0.10), action=(eth.dst = eth.src; eth.src = xreg0[[0..47]]; arp.op = 2; /* ARP reply */ 
arp.tha = arp.sha; arp.sha = xreg0[[0..47]]; arp.tpa <-> arp.spa; outport = inport; 
flags.loopback = 1; output;)
+  table=??(lr_in_ip_input     ), priority=90   , match=(arp.op == 1 && arp.tpa == 
172.16.1.10), action=(eth.dst = eth.src; eth.src = xreg0[[0..47]]; arp.op = 2; /* ARP reply 
*/ arp.tha = arp.sha; arp.sha = xreg0[[0..47]]; arp.tpa <-> arp.spa; outport = inport; 
flags.loopback = 1; output;)
+  table=??(lr_in_ip_input     ), priority=90   , match=(arp.op == 1 && arp.tpa == 
192.168.0.10), action=(eth.dst = eth.src; eth.src = xreg0[[0..47]]; arp.op = 2; /* ARP reply 
*/ arp.tha = arp.sha; arp.sha = xreg0[[0..47]]; arp.tpa <-> arp.spa; outport = inport; 
flags.loopback = 1; output;)
+  table=??(lr_in_ip_input     ), priority=91   , match=(inport == "DR-S1" && arp.op == 
1 && arp.tpa == 172.16.1.10), action=(drop;)
+  table=??(lr_in_ip_input     ), priority=91   , match=(inport == "DR-S2" && arp.op == 
1 && arp.tpa == 10.0.0.10), action=(drop;)
+  table=??(lr_in_ip_input     ), priority=91   , match=(inport == "DR-S3" && arp.op == 
1 && arp.tpa == 192.168.0.10), action=(drop;)
+  table=??(lr_in_ip_input     ), priority=92   , match=(inport == "DR-S1" && arp.op == 1 && arp.tpa == 
172.16.1.10 && is_chassis_resident("cr-DR-S1")), action=(eth.dst = eth.src; eth.src = xreg0[[0..47]]; arp.op = 
2; /* ARP reply */ arp.tha = arp.sha; arp.sha = xreg0[[0..47]]; arp.tpa <-> arp.spa; outport = inport; flags.loopback = 1; 
output;)
+  table=??(lr_in_ip_input     ), priority=92   , match=(inport == "DR-S2" && arp.op == 1 && arp.tpa == 
10.0.0.10 && is_chassis_resident("cr-DR-S2")), action=(eth.dst = eth.src; eth.src = xreg0[[0..47]]; arp.op = 2; 
/* ARP reply */ arp.tha = arp.sha; arp.sha = xreg0[[0..47]]; arp.tpa <-> arp.spa; outport = inport; flags.loopback = 1; 
output;)
+  table=??(lr_in_ip_input     ), priority=92   , match=(inport == "DR-S3" && arp.op == 1 && arp.tpa == 
192.168.0.10 && is_chassis_resident("cr-DR-S3")), action=(eth.dst = eth.src; eth.src = xreg0[[0..47]]; arp.op = 
2; /* ARP reply */ arp.tha = arp.sha; arp.sha = xreg0[[0..47]]; arp.tpa <-> arp.spa; outport = inport; flags.loopback = 1; 
output;)
+])
+}
+
+check_lr_in_unsnat_flows() {
+    AT_CHECK([grep lr_in_unsnat lrflows | grep ct_snat | sed 
's/table=../table=??/' | sort], [0], [dnl
+  table=??(lr_in_unsnat       ), priority=100  , match=(ip && ip4.dst == 10.0.0.10 && inport == "DR-S2" 
&& flags.loopback == 0 && is_chassis_resident("cr-DR-S2")), action=(ct_snat_in_czone;)
+  table=??(lr_in_unsnat       ), priority=100  , match=(ip && ip4.dst == 10.0.0.10 && inport == "DR-S2" 
&& flags.loopback == 1 && flags.use_snat_zone == 1 && is_chassis_resident("cr-DR-S2")), action=(ct_snat;)
+  table=??(lr_in_unsnat       ), priority=100  , match=(ip && ip4.dst == 172.16.1.10 && inport == 
"DR-S1" && flags.loopback == 0 && is_chassis_resident("cr-DR-S1")), action=(ct_snat_in_czone;)
+  table=??(lr_in_unsnat       ), priority=100  , match=(ip && ip4.dst == 172.16.1.10 && inport == "DR-S1" 
&& flags.loopback == 1 && flags.use_snat_zone == 1 && is_chassis_resident("cr-DR-S1")), action=(ct_snat;)
+  table=??(lr_in_unsnat       ), priority=100  , match=(ip && ip4.dst == 192.168.0.10 && inport == 
"DR-S3" && flags.loopback == 0 && is_chassis_resident("cr-DR-S3")), action=(ct_snat_in_czone;)
+  table=??(lr_in_unsnat       ), priority=100  , match=(ip && ip4.dst == 192.168.0.10 && inport == "DR-S3" 
&& flags.loopback == 1 && flags.use_snat_zone == 1 && is_chassis_resident("cr-DR-S3")), action=(ct_snat;)
+])
+}
+
+check_lr_out_snat_flows() {
+    AT_CHECK([grep lr_out_snat lrflows | grep ct_snat | sed 
's/table=../table=??/' | sort], [0], [dnl
+  table=??(lr_out_snat        ), priority=161  , match=(ip && ip4.src == 20.0.0.10 && outport == 
"DR-S1" && is_chassis_resident("cr-DR-S1")), action=(ct_snat_in_czone(172.16.1.10);)
+  table=??(lr_out_snat        ), priority=161  , match=(ip && ip4.src == 20.0.0.10 && outport == 
"DR-S2" && is_chassis_resident("cr-DR-S2")), action=(ct_snat_in_czone(10.0.0.10);)
+  table=??(lr_out_snat        ), priority=161  , match=(ip && ip4.src == 20.0.0.10 && outport == 
"DR-S3" && is_chassis_resident("cr-DR-S3")), action=(ct_snat_in_czone(192.168.0.10);)
+  table=??(lr_out_snat        ), priority=162  , match=(ip && ip4.src == 20.0.0.10 && outport == "DR-S1" 
&& is_chassis_resident("cr-DR-S1") && reg9[[4]] == 1), action=(reg9[[4]] = 0; ct_snat(172.16.1.10);)
+  table=??(lr_out_snat        ), priority=162  , match=(ip && ip4.src == 20.0.0.10 && outport == "DR-S2" 
&& is_chassis_resident("cr-DR-S2") && reg9[[4]] == 1), action=(reg9[[4]] = 0; ct_snat(10.0.0.10);)
+  table=??(lr_out_snat        ), priority=162  , match=(ip && ip4.src == 20.0.0.10 && outport == "DR-S3" 
&& is_chassis_resident("cr-DR-S3") && reg9[[4]] == 1), action=(reg9[[4]] = 0; ct_snat(192.168.0.10);)
+])
+}
+
+check_lr_in_unsnat_flows
+check_lr_out_snat_flows
+check_lr_in_arp_nat_flows
+
+check ovn-nbctl lr-nat-del DR snat 20.0.0.10
+AT_CHECK([ovn-sbctl dump-flows DR | grep -e lr_in_unsnat -e lr_out_snat | grep 
ct_snat | wc -l], [0], [0
+])
+
+# Configure DNAT
+check ovn-nbctl --gateway-port=DR-S1 lr-nat-add DR dnat  172.16.1.10    
20.0.0.10
+check ovn-nbctl --gateway-port=DR-S2 lr-nat-add DR dnat  10.0.0.10      
20.0.0.10
+check ovn-nbctl --gateway-port=DR-S3 lr-nat-add DR dnat  192.168.0.10   
20.0.0.10
+
+ovn-sbctl dump-flows DR > lrflows
+AT_CAPTURE_FILE([lrflows])
+
+check_lr_in_dnat_flows() {
+    AT_CHECK([grep lr_in_dnat lrflows | grep ct_dnat | sed 
's/table=../table=??/' | sort], [0], [dnl
+  table=??(lr_in_dnat         ), priority=100  , match=(ip && ip4.dst == 10.0.0.10 && inport == 
"DR-S2" && is_chassis_resident("cr-DR-S2")), action=(ct_dnat_in_czone(20.0.0.10);)
+  table=??(lr_in_dnat         ), priority=100  , match=(ip && ip4.dst == 172.16.1.10 && inport == 
"DR-S1" && is_chassis_resident("cr-DR-S1")), action=(ct_dnat_in_czone(20.0.0.10);)
+  table=??(lr_in_dnat         ), priority=100  , match=(ip && ip4.dst == 192.168.0.10 && inport == 
"DR-S3" && is_chassis_resident("cr-DR-S3")), action=(ct_dnat_in_czone(20.0.0.10);)
+])
+}
+
+check_lr_out_undnat_flows() {
+    AT_CHECK([grep lr_out_undnat lrflows | grep ct_dnat | sed 
's/table=../table=??/' | sort], [0], [dnl
+  table=??(lr_out_undnat      ), priority=100  , match=(ip && ip4.src == 20.0.0.10 && outport == 
"DR-S1" && is_chassis_resident("cr-DR-S1")), action=(ct_dnat_in_czone;)
+  table=??(lr_out_undnat      ), priority=100  , match=(ip && ip4.src == 20.0.0.10 && outport == 
"DR-S2" && is_chassis_resident("cr-DR-S2")), action=(ct_dnat_in_czone;)
+  table=??(lr_out_undnat      ), priority=100  , match=(ip && ip4.src == 20.0.0.10 && outport == 
"DR-S3" && is_chassis_resident("cr-DR-S3")), action=(ct_dnat_in_czone;)
+])
+}
+
+check_lr_in_dnat_flows
+check_lr_out_undnat_flows
+check_lr_in_arp_nat_flows
+
+check ovn-nbctl lr-nat-del DR dnat
+
+AT_CHECK([ovn-sbctl dump-flows DR | grep -e lr_in_dnat -e lr_out_undnat | grep 
ct_dnat | wc -l], [0], [0
+])
+
+# Configure DNAT_AND_SNAT
+check ovn-nbctl --gateway-port=DR-S1 lr-nat-add DR dnat_and_snat  172.16.1.10  
  20.0.0.10
+check ovn-nbctl --gateway-port=DR-S2 lr-nat-add DR dnat_and_snat  10.0.0.10    
  20.0.0.10
+check ovn-nbctl --gateway-port=DR-S3 lr-nat-add DR dnat_and_snat  192.168.0.10 
  20.0.0.10
+
+ovn-sbctl dump-flows DR > lrflows
+AT_CAPTURE_FILE([lrflows])
+
+check_lr_in_unsnat_flows
+check_lr_out_snat_flows
+check_lr_in_dnat_flows
+check_lr_out_undnat_flows
+check_lr_in_arp_nat_flows
+
+check ovn-nbctl lr-nat-del DR dnat_and_snat
+
+AT_CHECK([ovn-sbctl dump-flows DR | grep -e lr_in_unsnat -e lr_out_snat -e 
lr_in_dnat -e lr_out_undnat | grep ct_snat| wc -l], [0], [0
+])
+
+AT_CLEANUP
+])
diff --git a/tests/ovn.at b/tests/ovn.at
index 69270601a..62b6ed7db 100644
--- a/tests/ovn.at
+++ b/tests/ovn.at
@@ -29272,7 +29272,7 @@ as hv2 check ovn-appctl -t ovn-controller recompute
  AT_CHECK([as hv2 ovs-ofctl dump-flows br-int table=24 | grep 10.0.1.2], [1])
# Enable dnat_and_snat on lr, and now hv2 should see flows for lsp1.
-AT_CHECK([ovn-nbctl --wait=hv lr-nat-add lr dnat_and_snat 192.168.0.1 10.0.1.3 
lsp1 f0:00:00:00:00:03])
+AT_CHECK([ovn-nbctl --wait=hv --gateway-port=lrp_lr_ls1 lr-nat-add lr 
dnat_and_snat 192.168.0.1 10.0.1.3 lsp1 f0:00:00:00:00:03])
  AT_CHECK([as hv2 ovs-ofctl dump-flows br-int table=24 | grep 10.0.1.2], [0], 
[ignore])
OVN_CLEANUP([hv1],[hv2])
diff --git a/utilities/ovn-nbctl.8.xml b/utilities/ovn-nbctl.8.xml
index 545f3bf27..1f75c3ebc 100644
--- a/utilities/ovn-nbctl.8.xml
+++ b/utilities/ovn-nbctl.8.xml
@@ -1135,7 +1135,7 @@
      <h2>NAT Commands</h2>
<dl>
-      <dt>[<code>--may-exist</code>] [<code>--stateless</code>]<code>lr-nat-add</code> <var>router</var> <var>type</var> 
<var>external_ip</var> <var>logical_ip</var> [<var>logical_port</var> <var>external_mac</var>]</dt>
+      <dt>[<code>--may-exist</code>] [<code>--stateless</code>] [<code>--gateway_port</code>=<var>GATEWAY_PORT</var>] <code>lr-nat-add</code> 
<var>router</var> <var>type</var> <var>external_ip</var> <var>logical_ip</var> [<var>logical_port</var> <var>external_mac</var>]</dt>
        <dd>
          <p>
            Adds the specified NAT to <var>router</var>.
@@ -1151,7 +1151,6 @@
            The <var>logical_port</var> is the name of an existing logical
            switch port where the <var>logical_ip</var> resides.
            The <var>external_mac</var> is an Ethernet address.
-          The <var>--stateless</var>
          </p>
          <p>
            When <code>--stateless</code> is specified then it implies that
@@ -1162,6 +1161,16 @@
            with any other NAT rule.
          </p>
+ <p>
+          <code>--gateway-port</code> option allows specifying the distributed
+          gateway port of <var>router</var> where the NAT rule needs to be
+          applied. <var>GATEWAY_PORT</var> should reference a
+          <ref table="Logical_Router_Port"/> row that is a distributed gateway
+          port of <var>router</var>. When <var>router</var> has multiple
+          distributed gateway ports, it is an error to not specify the
+          <var>GATEWAY_PORT</var>.
+        </p>
+
          <p>
            When <var>type</var> is <code>dnat</code>, the externally
            visible IP address <var>external_ip</var> is DNATted to the
@@ -1194,30 +1203,33 @@
          <p>
            It is an error if a NAT already exists with the same values
            of <var>router</var>, <var>type</var>, <var>external_ip</var>,
-          and <var>logical_ip</var>, unless <code>--may-exist</code> is
-          specified.  When <code>--may-exist</code>,
+          <var>logical_ip</var> and <var>GATEWAY_PORT</var> (in case of
+          multiple distributed gateway ports), unless <code>--may-exist</code>
+          is specified.  When <code>--may-exist</code>,
            <var>logical_port</var>, and <var>external_mac</var> are all
            specified, the existing values of <var>logical_port</var> and
            <var>external_mac</var> are overwritten.
          </p>
        </dd>
- <dt>[<code>--if-exists</code>] <code>lr-nat-del</code> <var>router</var> [<var>type</var> [<var>ip</var>]]</dt>
+      <dt>[<code>--if-exists</code>] <code>lr-nat-del</code> <var>router</var> [<var>type</var> 
[<var>ip</var> [<var>gateway_port</var>]]]</dt>
        <dd>
          <p>
            Deletes NATs from <var>router</var>.  If only <var>router</var>
            is supplied, all the NATs from the logical router are
            deleted.  If <var>type</var> is also specified, then all the
            NATs that match the <var>type</var> will be deleted from the logical
-          router.  If all the fields are given, then a single NAT rule
-          that matches all the fields will be deleted.  When <var>type</var>
-          is <code>snat</code>, the <var>ip</var> should be logical_ip.
-          When <var>type</var> is <code>dnat</code> or
+          router. If <var>ip</var> is also specified, then all the
+          NATs that match the <var>type</var> and <var>ip</var> will be
+          deleted from the logical router. If all the fields are given, then
+          a single NAT rule that matches all the fields will be deleted.
+          When <var>type</var> is <code>snat</code>, the <var>ip</var> should
+          be logical_ip. When <var>type</var> is <code>dnat</code> or
            <code>dnat_and_snat</code>, the <var>ip</var> shoud be external_ip.
          </p>
<p>
-          It is an error if <var>ip</var> is specified and there
+          It is an error if <var>gateway_port</var> is specified and there
            is no matching NAT entry, unless <code>--if-exists</code> is
            specified.
          </p>
diff --git a/utilities/ovn-nbctl.c b/utilities/ovn-nbctl.c
index adb08c6c9..163e64b67 100644
--- a/utilities/ovn-nbctl.c
+++ b/utilities/ovn-nbctl.c
@@ -378,10 +378,11 @@ NAT commands:\n\
    [--stateless]\n\
    [--portrange]\n\
    [--add-route]\n\
+  [--gateway-port=GATEWAY_PORT]\n\
    lr-nat-add ROUTER TYPE EXTERNAL_IP LOGICAL_IP [LOGICAL_PORT EXTERNAL_MAC]\n\
                              [EXTERNAL_PORT_RANGE]\n\
                              add a NAT to ROUTER\n\
-  lr-nat-del ROUTER [TYPE [IP]]\n\
+  lr-nat-del ROUTER [TYPE [IP [GATEWAY_PORT]]]\n\
                              remove NATs from ROUTER\n\
    lr-nat-list ROUTER        print NATs for ROUTER\n\
  \n\
@@ -4557,6 +4558,7 @@ nbctl_pre_lr_nat_add(struct ctl_context *ctx)
  {
      ovsdb_idl_add_column(ctx->idl, &nbrec_logical_router_col_name);
      ovsdb_idl_add_column(ctx->idl, &nbrec_logical_router_col_nat);
+    ovsdb_idl_add_column(ctx->idl, &nbrec_logical_router_col_ports);
ovsdb_idl_add_column(ctx->idl, &nbrec_logical_switch_port_col_name); @@ -4565,7 +4567,14 @@ nbctl_pre_lr_nat_add(struct ctl_context *ctx)
      ovsdb_idl_add_column(ctx->idl, &nbrec_nat_col_type);
      ovsdb_idl_add_column(ctx->idl, &nbrec_nat_col_logical_port);
      ovsdb_idl_add_column(ctx->idl, &nbrec_nat_col_external_mac);
+    ovsdb_idl_add_column(ctx->idl, &nbrec_nat_col_gateway_port);
      ovsdb_idl_add_column(ctx->idl, &nbrec_nat_col_options);
+
+    ovsdb_idl_add_column(ctx->idl, &nbrec_logical_router_port_col_name);
+    ovsdb_idl_add_column(ctx->idl,
+                         &nbrec_logical_router_port_col_gateway_chassis);
+    ovsdb_idl_add_column(ctx->idl,
+                         &nbrec_logical_router_port_col_ha_chassis_group);
  }
static void
@@ -4700,6 +4709,52 @@ nbctl_lr_nat_add(struct ctl_context *ctx)
          ctl_error(ctx, "routes cannot be added for snat types.");
          goto cleanup;
      }
+
+    const char *dgw_port_name = shash_find_data(&ctx->options,
+                                                "--gateway-port");
+    const struct nbrec_logical_router_port *dgw_port = NULL;
+    if (dgw_port_name) {
+        error = lrp_by_name_or_uuid(ctx, dgw_port_name,
+                                    true, &dgw_port);
+        if (error) {
+            ctx->error = error;
+            goto cleanup;
+        }
+
+        bool nat_lr_port = false;
+        for (size_t i = 0; i < lr->n_ports; i++) {
+            const struct nbrec_logical_router_port *lrp = lr->ports[i];
+            if (lrp == dgw_port) {
+                nat_lr_port = true;
+            }
+        }
+        if (!nat_lr_port) {
+            ctl_error(ctx, "%s is not a router port of logical router: %s.",
+                      dgw_port_name, ctx->argv[1]);
+            goto cleanup;
+        }
+
+        if (!dgw_port->ha_chassis_group && !dgw_port->n_gateway_chassis) {
+            ctl_error(ctx, "%s is not a distributed gateway router port.",
+                      dgw_port_name);
+            goto cleanup;
+        }
+    } else {
+        size_t num_l3dgw_ports = 0;
+        for (size_t i = 0; i < lr->n_ports; i++) {
+            const struct nbrec_logical_router_port *lrp = lr->ports[i];
+            if (lrp->ha_chassis_group || lrp->n_gateway_chassis) {
+                num_l3dgw_ports++;
+            }
+        }
+        if (num_l3dgw_ports > 1) {
+            ctl_error(ctx, "logical router: %s has multiple distributed "
+                      "gateway ports. NAT rule needs to specify "
+                      "gateway_port.", ctx->argv[1]);
+            goto cleanup;
+        }
+    }
+
      for (size_t i = 0; i < lr->n_nat; i++) {
          const struct nbrec_nat *nat = lr->nat[i];
@@ -4716,7 +4771,8 @@ nbctl_lr_nat_add(struct ctl_context *ctx)
              continue;
          }
- if (!strcmp(nat_type, nat->type)) {
+        if (!strcmp(nat_type, nat->type) &&
+            dgw_port == nat->gateway_port) {
              if (!strcmp(is_snat ? new_logical_ip : new_external_ip,
                          is_snat ? old_logical_ip : old_external_ip)) {
                  if (!strcmp(is_snat ? new_external_ip : new_logical_ip,
@@ -4728,18 +4784,20 @@ nbctl_lr_nat_add(struct ctl_context *ctx)
                              nbrec_nat_set_external_mac(nat, external_mac);
                              should_return = true;
                          } else {
-                            ctl_error(ctx, "%s, %s: a NAT with this "
-                                      "external_ip and logical_ip already "
-                                      "exists", new_external_ip,
-                                      new_logical_ip);
+                            ctl_error(ctx, "%s, %s, %s: a NAT with this "
+                                      "external_ip, logical_ip and "
+                                      "gateway_port already exists",
+                                      new_external_ip, new_logical_ip,
+                                      dgw_port ? dgw_port->name : "");
                              should_return = true;
                          }
                  } else {
-                    ctl_error(ctx, "a NAT with this type (%s) and %s (%s) "
-                              "already exists",
+                    ctl_error(ctx, "a NAT with this type (%s), %s (%s) "
+                              "and gateway_port (%s) already exists",
                                nat_type,
                                is_snat ? "logical_ip" : "external_ip",
-                              is_snat ? new_logical_ip : new_external_ip);
+                              is_snat ? new_logical_ip : new_external_ip,
+                              dgw_port ? dgw_port->name : "");
                      should_return = true;
                  }
              }
@@ -4783,6 +4841,10 @@ nbctl_lr_nat_add(struct ctl_context *ctx)
      if (add_route) {
          smap_add(&nat_options, "add_route", "true");
      }
+
+    if (dgw_port) {
+        nbrec_nat_update_gateway_port_addvalue(nat, dgw_port);
+    }
      nbrec_nat_set_options(nat, &nat_options);
smap_destroy(&nat_options);
@@ -4804,6 +4866,9 @@ nbctl_pre_lr_nat_del(struct ctl_context *ctx)
      ovsdb_idl_add_column(ctx->idl, &nbrec_nat_col_type);
      ovsdb_idl_add_column(ctx->idl, &nbrec_nat_col_logical_ip);
      ovsdb_idl_add_column(ctx->idl, &nbrec_nat_col_external_ip);
+    ovsdb_idl_add_column(ctx->idl, &nbrec_nat_col_gateway_port);
+
+    ovsdb_idl_add_column(ctx->idl, &nbrec_logical_router_port_col_name);
  }
static void
@@ -4850,7 +4915,32 @@ nbctl_lr_nat_del(struct ctl_context *ctx)
      }
int is_snat = !strcmp("snat", nat_type);
-    /* Remove the matching NAT. */
+    if (ctx->argc == 4) {
+        /* Remove NAT rules matching the type and IP (based on type). */
+        for (size_t i = 0; i < lr->n_nat; i++) {
+            struct nbrec_nat *nat = lr->nat[i];
+            char *old_ip = normalize_prefix_str(is_snat
+                                                ? nat->logical_ip
+                                                : nat->external_ip);
+            if (!old_ip) {
+                continue;
+            }
+            if (!strcmp(nat_type, nat->type) && !strcmp(nat_ip, old_ip)) {
+                nbrec_logical_router_update_nat_delvalue(lr, nat);
+            }
+            free(old_ip);
+        }
+        goto cleanup;
+    }
+
+    const struct nbrec_logical_router_port *dgw_port = NULL;
+    error = lrp_by_name_or_uuid(ctx, ctx->argv[4], true, &dgw_port);
+    if (error) {
+        ctx->error = error;
+        goto cleanup;
+    }
+
+    /* Remove matching NAT. */
      for (size_t i = 0; i < lr->n_nat; i++) {
          struct nbrec_nat *nat = lr->nat[i];
          bool should_return = false;
@@ -4860,19 +4950,21 @@ nbctl_lr_nat_del(struct ctl_context *ctx)
          if (!old_ip) {
              continue;
          }
-        if (!strcmp(nat_type, nat->type) && !strcmp(nat_ip, old_ip)) {
+        if (!strcmp(nat_type, nat->type) && !strcmp(nat_ip, old_ip) &&
+            nat->gateway_port == dgw_port) {
              nbrec_logical_router_update_nat_delvalue(lr, nat);
              should_return = true;
          }
          free(old_ip);
-        if (should_return) {
+        if (should_return)
              goto cleanup;
-        }
      }
if (must_exist) {
-        ctl_error(ctx, "no matching NAT with the type (%s) and %s (%s)",
-                  nat_type, is_snat ? "logical_ip" : "external_ip", nat_ip);
+        ctl_error(ctx, "no matching NAT with the type (%s), %s (%s) and "
+                  "gateway_port (%s)", nat_type,
+                  is_snat ? "logical_ip" : "external_ip", nat_ip,
+                  ctx->argv[4]);
      }
cleanup:
@@ -4891,6 +4983,9 @@ nbctl_pre_lr_nat_list(struct ctl_context *ctx)
      ovsdb_idl_add_column(ctx->idl, &nbrec_nat_col_logical_ip);
      ovsdb_idl_add_column(ctx->idl, &nbrec_nat_col_external_mac);
      ovsdb_idl_add_column(ctx->idl, &nbrec_nat_col_logical_port);
+    ovsdb_idl_add_column(ctx->idl, &nbrec_nat_col_gateway_port);
+
+    ovsdb_idl_add_column(ctx->idl, &nbrec_logical_router_port_col_name);
  }
static void
@@ -4906,11 +5001,18 @@ nbctl_lr_nat_list(struct ctl_context *ctx)
      struct smap lr_nats = SMAP_INITIALIZER(&lr_nats);
      for (size_t i = 0; i < lr->n_nat; i++) {
          const struct nbrec_nat *nat = lr->nat[i];
-        char *key = xasprintf("%-17.13s%s", nat->type, nat->external_ip);
+        char *key = xasprintf("%-17.13s%-22.18s%s",
+                              nat->type,
+                              nat->gateway_port
+                              ? nat->gateway_port->name
+                              : "",
+                              nat->external_ip);
          if (nat->external_mac && nat->logical_port) {
-            smap_add_format(&lr_nats, key, "%-17.13s%-22.18s%-21.17s%s",
+            smap_add_format(&lr_nats, key,
+                            "%-17.13s%-20.16s%-21.17s%s",
                              nat->external_port_range,
-                            nat->logical_ip, nat->external_mac,
+                            nat->logical_ip,
+                            nat->external_mac,
                              nat->logical_port);
          } else {
              smap_add_format(&lr_nats, key, "%-17.13s%s",
@@ -4923,12 +5025,12 @@ nbctl_lr_nat_list(struct ctl_context *ctx)
      const struct smap_node **nodes = smap_sort(&lr_nats);
      if (nodes) {
          ds_put_format(&ctx->output,
-                "%-17.13s%-19.15s%-17.13s%-22.18s%-21.17s%s\n",
-                "TYPE", "EXTERNAL_IP", "EXTERNAL_PORT", "LOGICAL_IP",
-                "EXTERNAL_MAC", "LOGICAL_PORT");
+                "%-17.13s%-22.18s%-19.15s%-17.13s%-20.16s%-21.17s%s\n",
+                "TYPE", "GATEWAY_PORT", "EXTERNAL_IP", "EXTERNAL_PORT",
+                "LOGICAL_IP", "EXTERNAL_MAC", "LOGICAL_PORT");
          for (size_t i = 0; i < smap_count(&lr_nats); i++) {
              const struct smap_node *node = nodes[i];
-            ds_put_format(&ctx->output, "%-36.32s%s\n",
+            ds_put_format(&ctx->output, "%-58.54s%s\n",
                      node->key, node->value);
          }
          free(nodes);
@@ -7099,8 +7201,9 @@ static const struct ctl_command_syntax nbctl_commands[] = 
{
        "ROUTER TYPE EXTERNAL_IP LOGICAL_IP"
        "[LOGICAL_PORT EXTERNAL_MAC] [EXTERNAL_PORT_RANGE]",
        nbctl_pre_lr_nat_add, nbctl_lr_nat_add,
-      NULL, "--may-exist,--stateless,--portrange,--add-route", RW },
-    { "lr-nat-del", 1, 3, "ROUTER [TYPE [IP]]",
+      NULL, "--may-exist,--stateless,--portrange,--add-route,"
+      "--gateway-port=", RW },
+    { "lr-nat-del", 1, 4, "ROUTER [TYPE [IP [GATEWAY_PORT]]]",
        nbctl_pre_lr_nat_del, nbctl_lr_nat_del, NULL, "--if-exists", RW },
      { "lr-nat-list", 1, 1, "ROUTER", nbctl_pre_lr_nat_list,
        nbctl_lr_nat_list, NULL, "", RO },


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