nat: deal with flows instead of sessions
[vpp.git] / src / plugins / nat / nat.c
old mode 100755 (executable)
new mode 100644 (file)
index b0c30d6..245689d
 #include <vnet/plugin/plugin.h>
 #include <nat/nat.h>
 #include <nat/nat_dpo.h>
-#include <nat/nat_ipfix_logging.h>
-#include <nat/nat_det.h>
-#include <nat/nat64.h>
-#include <nat/nat66.h>
+#include <nat/lib/ipfix_logging.h>
+#include <nat/lib/nat_syslog.h>
 #include <nat/nat_inlines.h>
 #include <nat/nat44/inlines.h>
 #include <nat/nat_affinity.h>
-#include <nat/nat_syslog.h>
-#include <nat/nat_ha.h>
 #include <vnet/fib/fib_table.h>
 #include <vnet/fib/ip4_fib.h>
 #include <vnet/ip/reass/ip4_sv_reass.h>
 #include <vppinfra/bihash_16_8.h>
+#include <nat/nat44/ed_inlines.h>
+#include <vnet/ip/ip_table.h>
+
+#include <nat/nat44-ei/nat44_ei_ha.h>
+#include <nat/nat44-ei/nat44_ei.h>
 
 #include <vpp/app/version.h>
+#include <nat/lib/nat_inlines.h>
 
 snat_main_t snat_main;
 
-fib_source_t nat_fib_src_hi;
-fib_source_t nat_fib_src_low;
+#define skip_if_disabled()                                                    \
+  do                                                                          \
+    {                                                                         \
+      snat_main_t *sm = &snat_main;                                           \
+      if (PREDICT_FALSE (!sm->enabled))                                       \
+       return;                                                               \
+    }                                                                         \
+  while (0)
+
+#define fail_if_enabled()                                                     \
+  do                                                                          \
+    {                                                                         \
+      snat_main_t *sm = &snat_main;                                           \
+      if (PREDICT_FALSE (sm->enabled))                                        \
+       {                                                                     \
+         nat_log_err ("plugin enabled");                                     \
+         return 1;                                                           \
+       }                                                                     \
+    }                                                                         \
+  while (0)
+
+#define fail_if_disabled()                                                    \
+  do                                                                          \
+    {                                                                         \
+      snat_main_t *sm = &snat_main;                                           \
+      if (PREDICT_FALSE (!sm->enabled))                                       \
+       {                                                                     \
+         nat_log_err ("plugin disabled");                                    \
+         return 1;                                                           \
+       }                                                                     \
+    }                                                                         \
+  while (0)
 
 /* *INDENT-OFF* */
 /* Hook up input features */
@@ -84,22 +116,6 @@ VNET_FEATURE_INIT (ip4_nat_classify, static) = {
   .node_name = "nat44-classify",
   .runs_after = VNET_FEATURES ("acl-plugin-in-ip4-fa","ip4-sv-reassembly-feature"),
 };
-VNET_FEATURE_INIT (ip4_snat_det_in2out, static) = {
-  .arc_name = "ip4-unicast",
-  .node_name = "nat44-det-in2out",
-  .runs_after = VNET_FEATURES ("acl-plugin-in-ip4-fa","ip4-sv-reassembly-feature"),
-};
-VNET_FEATURE_INIT (ip4_snat_det_out2in, static) = {
-  .arc_name = "ip4-unicast",
-  .node_name = "nat44-det-out2in",
-  .runs_after = VNET_FEATURES ("acl-plugin-in-ip4-fa","ip4-sv-reassembly-feature",
-                               "ip4-dhcp-client-detect"),
-};
-VNET_FEATURE_INIT (ip4_nat_det_classify, static) = {
-  .arc_name = "ip4-unicast",
-  .node_name = "nat44-det-classify",
-  .runs_after = VNET_FEATURES ("acl-plugin-in-ip4-fa","ip4-sv-reassembly-feature"),
-};
 VNET_FEATURE_INIT (ip4_nat44_ed_in2out, static) = {
   .arc_name = "ip4-unicast",
   .node_name = "nat44-ed-in2out",
@@ -137,11 +153,6 @@ VNET_FEATURE_INIT (ip4_snat_hairpin_dst, static) = {
   .node_name = "nat44-hairpin-dst",
   .runs_after = VNET_FEATURES ("acl-plugin-in-ip4-fa","ip4-sv-reassembly-feature"),
 };
-VNET_FEATURE_INIT (ip4_nat44_ed_hairpin_dst, static) = {
-  .arc_name = "ip4-unicast",
-  .node_name = "nat44-ed-hairpin-dst",
-  .runs_after = VNET_FEATURES ("acl-plugin-in-ip4-fa","ip4-sv-reassembly-feature"),
-};
 
 /* Hook up output features */
 VNET_FEATURE_INIT (ip4_snat_in2out_output, static) = {
@@ -159,15 +170,15 @@ VNET_FEATURE_INIT (ip4_snat_hairpin_src, static) = {
   .node_name = "nat44-hairpin-src",
   .runs_after = VNET_FEATURES ("acl-plugin-out-ip4-fa","ip4-sv-reassembly-output-feature"),
 };
-VNET_FEATURE_INIT (ip4_nat44_ed_in2out_output, static) = {
+VNET_FEATURE_INIT (nat_pre_in2out_output, static) = {
   .arc_name = "ip4-output",
-  .node_name = "nat44-ed-in2out-output",
+  .node_name = "nat-pre-in2out-output",
   .runs_after = VNET_FEATURES ("ip4-sv-reassembly-output-feature"),
   .runs_before = VNET_FEATURES ("acl-plugin-out-ip4-fa"),
 };
-VNET_FEATURE_INIT (ip4_nat44_ed_hairpin_src, static) = {
+VNET_FEATURE_INIT (ip4_nat44_ed_in2out_output, static) = {
   .arc_name = "ip4-output",
-  .node_name = "nat44-ed-hairpin-src",
+  .node_name = "nat44-ed-in2out-output",
   .runs_after = VNET_FEATURES ("ip4-sv-reassembly-output-feature"),
   .runs_before = VNET_FEATURES ("acl-plugin-out-ip4-fa"),
 };
@@ -179,13 +190,6 @@ VNET_FEATURE_INIT (ip4_nat_hairpinning, static) =
   .node_name = "nat44-hairpinning",
   .runs_before = VNET_FEATURES("ip4-local-end-of-arc"),
 };
-VNET_FEATURE_INIT (ip4_nat44_ed_hairpinning, static) =
-{
-  .arc_name = "ip4-local",
-  .node_name = "nat44-ed-hairpinning",
-  .runs_before = VNET_FEATURES("ip4-local-end-of-arc"),
-};
-
 
 VLIB_PLUGIN_REGISTER () = {
     .version = VPP_BUILD_VER,
@@ -193,38 +197,99 @@ VLIB_PLUGIN_REGISTER () = {
 };
 /* *INDENT-ON* */
 
+static void nat44_ed_db_init (u32 translations, u32 translation_buckets,
+                             u32 user_buckets);
+
+static void nat44_ed_db_free ();
+
+static u32
+nat44_ed_get_worker_out2in_cb (vlib_buffer_t * b, ip4_header_t * ip,
+                              u32 rx_fib_index, u8 is_output);
+
+static u32
+nat44_ed_get_worker_in2out_cb (ip4_header_t * ip, u32 rx_fib_index,
+                              u8 is_output);
+
+u32 nat_calc_bihash_buckets (u32 n_elts);
+
+u8 *
+format_session_kvp (u8 * s, va_list * args)
+{
+  clib_bihash_kv_8_8_t *v = va_arg (*args, clib_bihash_kv_8_8_t *);
+
+  s = format (s, "%U session-index %llu", format_snat_key, v->key, v->value);
+
+  return s;
+}
+
+u8 *
+format_static_mapping_kvp (u8 * s, va_list * args)
+{
+  clib_bihash_kv_8_8_t *v = va_arg (*args, clib_bihash_kv_8_8_t *);
+
+  s = format (s, "%U static-mapping-index %llu",
+             format_snat_key, v->key, v->value);
+
+  return s;
+}
+
+u8 *
+format_user_kvp (u8 * s, va_list * args)
+{
+  clib_bihash_kv_8_8_t *v = va_arg (*args, clib_bihash_kv_8_8_t *);
+  snat_user_key_t k;
+
+  k.as_u64 = v->key;
+
+  s = format (s, "%U fib %d user-index %llu", format_ip4_address, &k.addr,
+             k.fib_index, v->value);
+
+  return s;
+}
+
+u8 *
+format_ed_session_kvp (u8 * s, va_list * args)
+{
+  clib_bihash_kv_16_8_t *v = va_arg (*args, clib_bihash_kv_16_8_t *);
+
+  u8 proto;
+  u16 r_port, l_port;
+  ip4_address_t l_addr, r_addr;
+  u32 fib_index;
+
+  split_ed_kv (v, &l_addr, &r_addr, &proto, &fib_index, &l_port, &r_port);
+  s = format (s,
+             "local %U:%d remote %U:%d proto %U fib %d thread-index %u "
+             "session-index %u",
+             format_ip4_address, &l_addr, clib_net_to_host_u16 (l_port),
+             format_ip4_address, &r_addr, clib_net_to_host_u16 (r_port),
+             format_ip_protocol, proto, fib_index,
+             ed_value_get_thread_index (v), ed_value_get_session_index (v));
+
+  return s;
+}
+
 void
 nat_free_session_data (snat_main_t * sm, snat_session_t * s, u32 thread_index,
                       u8 is_ha)
 {
-  snat_session_key_t key;
   clib_bihash_kv_8_8_t kv;
-  nat_ed_ses_key_t ed_key;
-  clib_bihash_kv_16_8_t ed_kv;
   snat_main_per_thread_data_t *tsm =
     vec_elt_at_index (sm->per_thread_data, thread_index);
 
+  if (is_ed_session (s))
+    {
+      per_vrf_sessions_unregister_session (s, thread_index);
+
+      if (nat_ed_ses_i2o_flow_hash_add_del (sm, thread_index, s, 0))
+       nat_elog_warn ("flow hash del failed");
+
+      if (nat_ed_ses_o2i_flow_hash_add_del (sm, thread_index, s, 0))
+       nat_elog_warn ("flow hash del failed");
+    }
+
   if (is_fwd_bypass_session (s))
     {
-      if (snat_is_unk_proto_session (s))
-       {
-         ed_key.proto = s->in2out.port;
-         ed_key.r_port = 0;
-         ed_key.l_port = 0;
-       }
-      else
-       {
-         ed_key.proto = snat_proto_to_ip_proto (s->in2out.protocol);
-         ed_key.l_port = s->in2out.port;
-         ed_key.r_port = s->ext_host_port;
-       }
-      ed_key.l_addr = s->in2out.addr;
-      ed_key.r_addr = s->ext_host_addr;
-      ed_key.fib_index = 0;
-      ed_kv.key[0] = ed_key.as_u64[0];
-      ed_kv.key[1] = ed_key.as_u64[1];
-      if (clib_bihash_add_del_16_8 (&tsm->in2out_ed, &ed_kv, 0))
-       nat_elog_warn ("in2out_ed key del failed");
       return;
     }
 
@@ -233,39 +298,7 @@ nat_free_session_data (snat_main_t * sm, snat_session_t * s, u32 thread_index,
     {
       if (is_affinity_sessions (s))
        nat_affinity_unlock (s->ext_host_addr, s->out2in.addr,
-                            s->in2out.protocol, s->out2in.port);
-      ed_key.l_addr = s->out2in.addr;
-      ed_key.r_addr = s->ext_host_addr;
-      ed_key.fib_index = s->out2in.fib_index;
-      if (snat_is_unk_proto_session (s))
-       {
-         ed_key.proto = s->in2out.port;
-         ed_key.r_port = 0;
-         ed_key.l_port = 0;
-       }
-      else
-       {
-         ed_key.proto = snat_proto_to_ip_proto (s->in2out.protocol);
-         ed_key.l_port = s->out2in.port;
-         ed_key.r_port = s->ext_host_port;
-       }
-      ed_kv.key[0] = ed_key.as_u64[0];
-      ed_kv.key[1] = ed_key.as_u64[1];
-      if (clib_bihash_add_del_16_8 (&tsm->out2in_ed, &ed_kv, 0))
-       nat_elog_warn ("out2in_ed key del failed");
-      ed_key.l_addr = s->in2out.addr;
-      ed_key.fib_index = s->in2out.fib_index;
-      if (!snat_is_unk_proto_session (s))
-       ed_key.l_port = s->in2out.port;
-      if (is_twice_nat_session (s))
-       {
-         ed_key.r_addr = s->ext_host_nat_addr;
-         ed_key.r_port = s->ext_host_nat_port;
-       }
-      ed_kv.key[0] = ed_key.as_u64[0];
-      ed_kv.key[1] = ed_key.as_u64[1];
-      if (clib_bihash_add_del_16_8 (&tsm->in2out_ed, &ed_kv, 0))
-       nat_elog_warn ("in2out_ed key del failed");
+                            s->nat_proto, s->out2in.port);
 
       if (!is_ha)
        nat_syslog_nat44_sdel (s->user_index, s->in2out.fib_index,
@@ -273,14 +306,14 @@ nat_free_session_data (snat_main_t * sm, snat_session_t * s, u32 thread_index,
                               &s->ext_host_nat_addr, s->ext_host_nat_port,
                               &s->out2in.addr, s->out2in.port,
                               &s->ext_host_addr, s->ext_host_port,
-                              s->in2out.protocol, is_twice_nat_session (s));
+                              s->nat_proto, is_twice_nat_session (s));
     }
   else
     {
-      kv.key = s->in2out.as_u64;
+      init_nat_i2o_k (&kv, s);
       if (clib_bihash_add_del_8_8 (&tsm->in2out, &kv, 0))
        nat_elog_warn ("in2out key del failed");
-      kv.key = s->out2in.as_u64;
+      init_nat_o2i_k (&kv, s);
       if (clib_bihash_add_del_8_8 (&tsm->out2in, &kv, 0))
        nat_elog_warn ("out2in key del failed");
 
@@ -288,7 +321,7 @@ nat_free_session_data (snat_main_t * sm, snat_session_t * s, u32 thread_index,
        nat_syslog_nat44_apmdel (s->user_index, s->in2out.fib_index,
                                 &s->in2out.addr, s->in2out.port,
                                 &s->out2in.addr, s->out2in.port,
-                                s->in2out.protocol);
+                                s->nat_proto);
     }
 
   if (snat_is_unk_proto_session (s))
@@ -297,163 +330,36 @@ nat_free_session_data (snat_main_t * sm, snat_session_t * s, u32 thread_index,
   if (!is_ha)
     {
       /* log NAT event */
-      snat_ipfix_logging_nat44_ses_delete (thread_index,
-                                          s->in2out.addr.as_u32,
-                                          s->out2in.addr.as_u32,
-                                          s->in2out.protocol,
-                                          s->in2out.port,
-                                          s->out2in.port,
-                                          s->in2out.fib_index);
-
-      nat_ha_sdel (&s->out2in.addr, s->out2in.port, &s->ext_host_addr,
-                  s->ext_host_port, s->out2in.protocol, s->out2in.fib_index,
-                  thread_index);
-    }
-
-  /* Twice NAT address and port for external host */
-  if (is_twice_nat_session (s))
-    {
-      key.protocol = s->in2out.protocol;
-      key.port = s->ext_host_nat_port;
-      key.addr.as_u32 = s->ext_host_nat_addr.as_u32;
-      snat_free_outside_address_and_port (sm->twice_nat_addresses,
-                                         thread_index, &key);
-    }
-
-  if (snat_is_session_static (s))
-    return;
-
-  snat_free_outside_address_and_port (sm->addresses, thread_index,
-                                     &s->out2in);
-}
-
-void
-nat44_free_session_data (snat_main_t * sm, snat_session_t * s,
-                        u32 thread_index, u8 is_ha)
-{
-  snat_session_key_t key;
-  nat_ed_ses_key_t ed_key;
-  clib_bihash_kv_16_8_t ed_kv;
-  snat_main_per_thread_data_t *tsm =
-    vec_elt_at_index (sm->per_thread_data, thread_index);
-
-  if (is_fwd_bypass_session (s))
-    {
-      if (snat_is_unk_proto_session (s))
-       {
-         ed_key.proto = s->in2out.port;
-         ed_key.r_port = 0;
-         ed_key.l_port = 0;
-       }
-      else
-       {
-         ed_key.proto = snat_proto_to_ip_proto (s->in2out.protocol);
-         ed_key.l_port = s->in2out.port;
-         ed_key.r_port = s->ext_host_port;
-       }
-
-      ed_key.l_addr = s->in2out.addr;
-      ed_key.r_addr = s->ext_host_addr;
-      ed_key.fib_index = 0;
-      ed_kv.key[0] = ed_key.as_u64[0];
-      ed_kv.key[1] = ed_key.as_u64[1];
-
-      if (PREDICT_FALSE
-         (clib_bihash_add_del_16_8 (&tsm->in2out_ed, &ed_kv, 0)))
-       nat_elog_warn ("in2out_ed key del failed");
-      return;
-    }
-
-  /* session lookup tables */
-  if (is_affinity_sessions (s))
-    nat_affinity_unlock (s->ext_host_addr, s->out2in.addr,
-                        s->in2out.protocol, s->out2in.port);
-  ed_key.l_addr = s->out2in.addr;
-  ed_key.r_addr = s->ext_host_addr;
-  ed_key.fib_index = s->out2in.fib_index;
-  if (snat_is_unk_proto_session (s))
-    {
-      ed_key.proto = s->in2out.port;
-      ed_key.r_port = 0;
-      ed_key.l_port = 0;
-    }
-  else
-    {
-      ed_key.proto = snat_proto_to_ip_proto (s->in2out.protocol);
-      ed_key.l_port = s->out2in.port;
-      ed_key.r_port = s->ext_host_port;
-    }
-  ed_kv.key[0] = ed_key.as_u64[0];
-  ed_kv.key[1] = ed_key.as_u64[1];
-
-  if (PREDICT_FALSE (clib_bihash_add_del_16_8 (&tsm->out2in_ed, &ed_kv, 0)))
-    nat_elog_warn ("out2in_ed key del failed");
-
-  ed_key.l_addr = s->in2out.addr;
-  ed_key.fib_index = s->in2out.fib_index;
-
-  if (!snat_is_unk_proto_session (s))
-    ed_key.l_port = s->in2out.port;
-
-  if (is_twice_nat_session (s))
-    {
-      ed_key.r_addr = s->ext_host_nat_addr;
-      ed_key.r_port = s->ext_host_nat_port;
-    }
-
-  ed_kv.key[0] = ed_key.as_u64[0];
-  ed_kv.key[1] = ed_key.as_u64[1];
-
-  if (PREDICT_FALSE (clib_bihash_add_del_16_8 (&tsm->in2out_ed, &ed_kv, 0)))
-    nat_elog_warn ("in2out_ed key del failed");
-
-  if (!is_ha)
-    {
-      nat_syslog_nat44_sdel (s->user_index, s->in2out.fib_index,
-                            &s->in2out.addr, s->in2out.port,
-                            &s->ext_host_nat_addr, s->ext_host_nat_port,
-                            &s->out2in.addr, s->out2in.port,
-                            &s->ext_host_addr, s->ext_host_port,
-                            s->in2out.protocol, is_twice_nat_session (s));
-    }
-
-  if (snat_is_unk_proto_session (s))
-    return;
+      nat_ipfix_logging_nat44_ses_delete (thread_index,
+                                         s->in2out.addr.as_u32,
+                                         s->out2in.addr.as_u32,
+                                         s->nat_proto,
+                                         s->in2out.port,
+                                         s->out2in.port,
+                                         s->in2out.fib_index);
 
-  // is this correct ?
-  if (!is_ha)
-    {
-      snat_ipfix_logging_nat44_ses_delete (thread_index,
-                                          s->in2out.addr.as_u32,
-                                          s->out2in.addr.as_u32,
-                                          s->in2out.protocol,
-                                          s->in2out.port,
-                                          s->out2in.port,
-                                          s->in2out.fib_index);
       nat_ha_sdel (&s->out2in.addr, s->out2in.port, &s->ext_host_addr,
-                  s->ext_host_port, s->out2in.protocol, s->out2in.fib_index,
+                  s->ext_host_port, s->nat_proto, s->out2in.fib_index,
                   thread_index);
     }
 
   /* Twice NAT address and port for external host */
   if (is_twice_nat_session (s))
     {
-      key.protocol = s->in2out.protocol;
-      key.port = s->ext_host_nat_port;
-      key.addr.as_u32 = s->ext_host_nat_addr.as_u32;
       snat_free_outside_address_and_port (sm->twice_nat_addresses,
-                                         thread_index, &key);
+                                         thread_index,
+                                         &s->ext_host_nat_addr,
+                                         s->ext_host_nat_port, s->nat_proto);
     }
 
   if (snat_is_session_static (s))
     return;
 
-  // should be called for every dynamic session
   snat_free_outside_address_and_port (sm->addresses, thread_index,
-                                     &s->out2in);
+                                     &s->out2in.addr, s->out2in.port,
+                                     s->nat_proto);
 }
 
-
 snat_user_t *
 nat_user_get_or_create (snat_main_t * sm, ip4_address_t * addr, u32 fib_index,
                        u32 thread_index)
@@ -471,6 +377,13 @@ nat_user_get_or_create (snat_main_t * sm, ip4_address_t * addr, u32 fib_index,
   /* Ever heard of the "user" = src ip4 address before? */
   if (clib_bihash_search_8_8 (&tsm->user_hash, &kv, &value))
     {
+      if (pool_elts (tsm->users) >= sm->max_users_per_thread)
+       {
+         vlib_increment_simple_counter (&sm->user_limit_reached,
+                                        thread_index, 0, 1);
+         nat_elog_warn ("maximum user limit reached");
+         return NULL;
+       }
       /* no, make a new one */
       pool_get (tsm->users, u);
       clib_memset (u, 0, sizeof (*u));
@@ -506,6 +419,7 @@ nat_user_get_or_create (snat_main_t * sm, ip4_address_t * addr, u32 fib_index,
   return u;
 }
 
+// only NAT EI
 snat_session_t *
 nat_session_alloc_or_recycle (snat_main_t * sm, snat_user_t * u,
                              u32 thread_index, f64 now)
@@ -539,6 +453,8 @@ nat_session_alloc_or_recycle (snat_main_t * sm, snat_user_t * u,
 
       /* Get the session */
       s = pool_elt_at_index (tsm->sessions, session_index);
+
+      // TODO: ONLY EI version should be called
       nat_free_session_data (sm, s, thread_index, 0);
       if (snat_is_session_static (s))
        u->nstaticsessions--;
@@ -571,14 +487,6 @@ nat_session_alloc_or_recycle (snat_main_t * sm, snat_user_t * u,
                          s->per_user_list_head_index,
                          per_user_translation_list_elt - tsm->list_pool);
 
-      dlist_elt_t *global_lru_list_elt;
-      pool_get (tsm->global_lru_pool, global_lru_list_elt);
-      global_lru_list_elt->value = s - tsm->sessions;
-      s->global_lru_index = global_lru_list_elt - tsm->global_lru_pool;
-      clib_dlist_addtail (tsm->global_lru_pool, tsm->global_lru_head_index,
-                         s->global_lru_index);
-      s->last_lru_update = now;
-
       s->user_index = u - tsm->users;
       vlib_set_simple_counter (&sm->total_sessions, thread_index, 0,
                               pool_elts (tsm->sessions));
@@ -589,62 +497,11 @@ nat_session_alloc_or_recycle (snat_main_t * sm, snat_user_t * u,
   return s;
 }
 
-int
-nat_global_lru_free_one (snat_main_t * sm, int thread_index, f64 now)
-{
-  snat_session_t *s = NULL;
-  dlist_elt_t *oldest_elt;
-  u64 sess_timeout_time;
-  u32 oldest_index;
-  snat_main_per_thread_data_t *tsm = &sm->per_thread_data[thread_index];
-  oldest_index = clib_dlist_remove_head (tsm->global_lru_pool,
-                                        tsm->global_lru_head_index);
-  if (~0 != oldest_index)
-    {
-      oldest_elt = pool_elt_at_index (tsm->global_lru_pool, oldest_index);
-      s = pool_elt_at_index (tsm->sessions, oldest_elt->value);
-
-      sess_timeout_time =
-       s->last_heard + (f64) nat44_session_get_timeout (sm, s);
-      if (now >= sess_timeout_time
-         || (s->tcp_close_timestamp && now >= s->tcp_close_timestamp))
-       {
-         nat_free_session_data (sm, s, thread_index, 0);
-         nat44_ed_delete_session (sm, s, thread_index, 0);
-         return 1;
-       }
-      else
-       {
-         clib_dlist_addhead (tsm->global_lru_pool,
-                             tsm->global_lru_head_index, oldest_index);
-       }
-    }
-  return 0;
-}
-
-snat_session_t *
-nat_ed_session_alloc (snat_main_t * sm, u32 thread_index, f64 now)
-{
-  snat_session_t *s;
-  snat_main_per_thread_data_t *tsm = &sm->per_thread_data[thread_index];
-
-  nat_global_lru_free_one (sm, thread_index, now);
-
-  pool_get (tsm->sessions, s);
-  clib_memset (s, 0, sizeof (*s));
-
-  nat44_global_lru_insert (tsm, s, now);
-
-  s->ha_last_refreshed = now;
-  vlib_set_simple_counter (&sm->total_sessions, thread_index, 0,
-                          pool_elts (tsm->sessions));
-  return s;
-}
-
 void
 snat_add_del_addr_to_fib (ip4_address_t * addr, u8 p_len, u32 sw_if_index,
                          int is_add)
 {
+  snat_main_t *sm = &snat_main;
   fib_prefix_t prefix = {
     .fp_len = p_len,
     .fp_proto = FIB_PROTOCOL_IP4,
@@ -657,7 +514,7 @@ snat_add_del_addr_to_fib (ip4_address_t * addr, u8 p_len, u32 sw_if_index,
   if (is_add)
     fib_table_entry_update_one_path (fib_index,
                                     &prefix,
-                                    nat_fib_src_low,
+                                    sm->fib_src_low,
                                     (FIB_ENTRY_FLAG_CONNECTED |
                                      FIB_ENTRY_FLAG_LOCAL |
                                      FIB_ENTRY_FLAG_EXCLUSIVE),
@@ -666,7 +523,7 @@ snat_add_del_addr_to_fib (ip4_address_t * addr, u8 p_len, u32 sw_if_index,
                                     sw_if_index,
                                     ~0, 1, NULL, FIB_ROUTE_PATH_FLAG_NONE);
   else
-    fib_table_entry_delete (fib_index, &prefix, nat_fib_src_low);
+    fib_table_entry_delete (fib_index, &prefix, sm->fib_src_low);
 }
 
 int
@@ -678,14 +535,20 @@ snat_add_address (snat_main_t * sm, ip4_address_t * addr, u32 vrf_id,
   vlib_thread_main_t *tm = vlib_get_thread_main ();
 
   if (twice_nat && !sm->endpoint_dependent)
-    return VNET_API_ERROR_FEATURE_DISABLED;
+    {
+      nat_log_err ("unsupported");
+      return VNET_API_ERROR_UNSUPPORTED;
+    }
 
   /* Check if address already exists */
   /* *INDENT-OFF* */
   vec_foreach (ap, twice_nat ? sm->twice_nat_addresses : sm->addresses)
     {
       if (ap->addr.as_u32 == addr->as_u32)
-        return VNET_API_ERROR_VALUE_EXIST;
+        {
+          nat_log_err ("address exist");
+          return VNET_API_ERROR_VALUE_EXIST;
+        }
     }
   /* *INDENT-ON* */
 
@@ -698,37 +561,41 @@ snat_add_address (snat_main_t * sm, ip4_address_t * addr, u32 vrf_id,
   if (vrf_id != ~0)
     ap->fib_index =
       fib_table_find_or_create_and_lock (FIB_PROTOCOL_IP4, vrf_id,
-                                        nat_fib_src_low);
+                                        sm->fib_src_low);
   else
     ap->fib_index = ~0;
-#define _(N, i, n, s) \
-  clib_memset(ap->busy_##n##_port_refcounts, 0, sizeof(ap->busy_##n##_port_refcounts));\
-  ap->busy_##n##_ports = 0; \
-  ap->busy_##n##_ports_per_thread = 0;\
-  vec_validate_init_empty (ap->busy_##n##_ports_per_thread, tm->n_vlib_mains - 1, 0);
-  foreach_snat_protocol
-#undef _
-    if (twice_nat)
+
+  /* *INDENT-OFF* */
+  #define _(N, i, n, s) \
+    clib_memset(ap->busy_##n##_port_refcounts, 0, sizeof(ap->busy_##n##_port_refcounts));\
+    ap->busy_##n##_ports = 0; \
+    ap->busy_##n##_ports_per_thread = 0;\
+    vec_validate_init_empty (ap->busy_##n##_ports_per_thread, tm->n_vlib_mains - 1, 0);
+    foreach_nat_protocol
+  #undef _
+  /* *INDENT-ON* */
+
+  if (twice_nat)
     return 0;
 
   /* Add external address to FIB */
   /* *INDENT-OFF* */
-  pool_foreach (i, sm->interfaces,
-  ({
+  pool_foreach (i, sm->interfaces)
+   {
     if (nat_interface_is_inside(i) || sm->out2in_dpo)
       continue;
 
     snat_add_del_addr_to_fib(addr, 32, i->sw_if_index, 1);
     break;
-  }));
-  pool_foreach (i, sm->output_feature_interfaces,
-  ({
+  }
+  pool_foreach (i, sm->output_feature_interfaces)
+   {
     if (nat_interface_is_inside(i) || sm->out2in_dpo)
       continue;
 
     snat_add_del_addr_to_fib(addr, 32, i->sw_if_index, 1);
     break;
-  }));
+  }
   /* *INDENT-ON* */
 
   return 0;
@@ -739,31 +606,27 @@ is_snat_address_used_in_static_mapping (snat_main_t * sm, ip4_address_t addr)
 {
   snat_static_mapping_t *m;
   /* *INDENT-OFF* */
-  pool_foreach (m, sm->static_mappings,
-  ({
+  pool_foreach (m, sm->static_mappings)
+   {
       if (is_addr_only_static_mapping (m) ||
           is_out2in_only_static_mapping (m) ||
           is_identity_static_mapping (m))
         continue;
       if (m->external_addr.as_u32 == addr.as_u32)
         return 1;
-  }));
+  }
   /* *INDENT-ON* */
 
   return 0;
 }
 
 static void
-snat_add_static_mapping_when_resolved (snat_main_t * sm,
-                                      ip4_address_t l_addr,
-                                      u16 l_port,
-                                      u32 sw_if_index,
-                                      u16 e_port,
-                                      u32 vrf_id,
-                                      snat_protocol_t proto,
-                                      int addr_only, int is_add, u8 * tag,
-                                      int twice_nat, int out2in_only,
-                                      int identity_nat)
+snat_add_static_mapping_when_resolved (snat_main_t *sm, ip4_address_t l_addr,
+                                      u16 l_port, u32 sw_if_index, u16 e_port,
+                                      u32 vrf_id, nat_protocol_t proto,
+                                      int addr_only, u8 *tag, int twice_nat,
+                                      int out2in_only, int identity_nat,
+                                      ip4_address_t pool_addr, int exact)
 {
   snat_static_map_resolve_t *rp;
 
@@ -775,14 +638,15 @@ snat_add_static_mapping_when_resolved (snat_main_t * sm,
   rp->vrf_id = vrf_id;
   rp->proto = proto;
   rp->addr_only = addr_only;
-  rp->is_add = is_add;
   rp->twice_nat = twice_nat;
   rp->out2in_only = out2in_only;
   rp->identity_nat = identity_nat;
   rp->tag = vec_dup (tag);
+  rp->pool_addr = pool_addr;
+  rp->exact = exact;
 }
 
-static u32
+u32
 get_thread_idx_by_port (u16 e_port)
 {
   snat_main_t *sm = &snat_main;
@@ -797,71 +661,18 @@ get_thread_idx_by_port (u16 e_port)
 }
 
 void
-snat_static_mapping_del_sessions (snat_main_t * sm,
-                                 snat_main_per_thread_data_t * tsm,
-                                 snat_user_key_t u_key, int addr_only,
-                                 ip4_address_t e_addr, u16 e_port)
-{
-  clib_bihash_kv_8_8_t kv, value;
-  kv.key = u_key.as_u64;
-  u64 user_index;
-  dlist_elt_t *head, *elt;
-  snat_user_t *u;
-  snat_session_t *s;
-  u32 elt_index, head_index, ses_index;
-  if (!clib_bihash_search_8_8 (&tsm->user_hash, &kv, &value))
-    {
-      user_index = value.value;
-      u = pool_elt_at_index (tsm->users, user_index);
-      if (u->nstaticsessions)
-       {
-         head_index = u->sessions_per_user_list_head_index;
-         head = pool_elt_at_index (tsm->list_pool, head_index);
-         elt_index = head->next;
-         elt = pool_elt_at_index (tsm->list_pool, elt_index);
-         ses_index = elt->value;
-         while (ses_index != ~0)
-           {
-             s = pool_elt_at_index (tsm->sessions, ses_index);
-             elt = pool_elt_at_index (tsm->list_pool, elt->next);
-             ses_index = elt->value;
-
-             if (!addr_only)
-               {
-                 if ((s->out2in.addr.as_u32 != e_addr.as_u32) ||
-                     (clib_net_to_host_u16 (s->out2in.port) != e_port))
-                   continue;
-               }
-
-             if (is_lb_session (s))
-               continue;
-
-             if (!snat_is_session_static (s))
-               continue;
-
-             nat_free_session_data (sm, s, tsm - sm->per_thread_data, 0);
-             nat44_delete_session (sm, s, tsm - sm->per_thread_data);
-
-             if (!addr_only)
-               break;
-           }
-       }
-    }
-}
-
-void
-snat_ed_static_mapping_del_sessions (snat_main_t * sm,
-                                    snat_main_per_thread_data_t * tsm,
-                                    ip4_address_t l_addr,
-                                    u16 l_port,
-                                    u8 protocol,
-                                    u32 fib_index, int addr_only,
-                                    ip4_address_t e_addr, u16 e_port)
+nat_ed_static_mapping_del_sessions (snat_main_t * sm,
+                                   snat_main_per_thread_data_t * tsm,
+                                   ip4_address_t l_addr,
+                                   u16 l_port,
+                                   u8 protocol,
+                                   u32 fib_index, int addr_only,
+                                   ip4_address_t e_addr, u16 e_port)
 {
   snat_session_t *s;
   u32 *indexes_to_free = NULL;
   /* *INDENT-OFF* */
-  pool_foreach (s, tsm->sessions, {
+  pool_foreach (s, tsm->sessions) {
     if (s->in2out.fib_index != fib_index ||
         s->in2out.addr.as_u32 != l_addr.as_u32)
       {
@@ -870,9 +681,9 @@ snat_ed_static_mapping_del_sessions (snat_main_t * sm,
     if (!addr_only)
       {
         if ((s->out2in.addr.as_u32 != e_addr.as_u32) ||
-            (clib_net_to_host_u16 (s->out2in.port) != e_port) ||
-            clib_net_to_host_u16 (s->in2out.port) != l_port ||
-            s->in2out.protocol != protocol)
+            s->out2in.port != e_port ||
+            s->in2out.port != l_port ||
+            s->nat_proto != protocol)
           continue;
       }
 
@@ -884,27 +695,28 @@ snat_ed_static_mapping_del_sessions (snat_main_t * sm,
     vec_add1 (indexes_to_free, s - tsm->sessions);
     if (!addr_only)
       break;
-  });
+  }
   /* *INDENT-ON* */
   u32 *ses_index;
   vec_foreach (ses_index, indexes_to_free)
   {
     s = pool_elt_at_index (tsm->sessions, *ses_index);
-    nat44_ed_delete_session (sm, s, tsm - sm->per_thread_data, 1);
+    nat_ed_session_delete (sm, s, tsm - sm->per_thread_data, 1);
   }
   vec_free (indexes_to_free);
 }
 
-int
-snat_add_static_mapping (ip4_address_t l_addr, ip4_address_t e_addr,
-                        u16 l_port, u16 e_port, u32 vrf_id, int addr_only,
-                        u32 sw_if_index, snat_protocol_t proto, int is_add,
-                        twice_nat_type_t twice_nat, u8 out2in_only, u8 * tag,
-                        u8 identity_nat)
+static_always_inline int
+nat44_ed_add_del_static_mapping (ip4_address_t l_addr, ip4_address_t e_addr,
+                                u16 l_port, u16 e_port, u32 vrf_id,
+                                int addr_only, u32 sw_if_index,
+                                nat_protocol_t proto, int is_add,
+                                twice_nat_type_t twice_nat, u8 out2in_only,
+                                u8 *tag, u8 identity_nat,
+                                ip4_address_t pool_addr, int exact)
 {
   snat_main_t *sm = &snat_main;
   snat_static_mapping_t *m;
-  snat_session_key_t m_key;
   clib_bihash_kv_8_8_t kv, value;
   snat_address_t *a = 0;
   u32 fib_index = ~0;
@@ -925,7 +737,7 @@ snat_add_static_mapping (ip4_address_t l_addr, ip4_address_t e_addr,
   if (!sm->endpoint_dependent)
     {
       if (twice_nat || out2in_only)
-       return VNET_API_ERROR_FEATURE_DISABLED;
+       return VNET_API_ERROR_UNSUPPORTED;
     }
 
   /* If the external address is a specific interface address */
@@ -961,9 +773,9 @@ snat_add_static_mapping (ip4_address_t l_addr, ip4_address_t e_addr,
          if (rp_match)
            return VNET_API_ERROR_VALUE_EXIST;
 
-         snat_add_static_mapping_when_resolved
-           (sm, l_addr, l_port, sw_if_index, e_port, vrf_id, proto,
-            addr_only, is_add, tag, twice_nat, out2in_only, identity_nat);
+         snat_add_static_mapping_when_resolved (
+           sm, l_addr, l_port, sw_if_index, e_port, vrf_id, proto, addr_only,
+           tag, twice_nat, out2in_only, identity_nat, pool_addr, exact);
 
          /* DHCP resolution required? */
          if (first_int_addr == 0)
@@ -997,11 +809,7 @@ snat_add_static_mapping (ip4_address_t l_addr, ip4_address_t e_addr,
        }
     }
 
-  m_key.addr = e_addr;
-  m_key.port = addr_only ? 0 : e_port;
-  m_key.protocol = addr_only ? 0 : proto;
-  m_key.fib_index = 0;
-  kv.key = m_key.as_u64;
+  init_nat_k (&kv, e_addr, addr_only ? 0 : e_port, 0, addr_only ? 0 : proto);
   if (clib_bihash_search_8_8 (&sm->static_mapping_by_external, &kv, &value))
     m = 0;
   else
@@ -1014,23 +822,20 @@ snat_add_static_mapping (ip4_address_t l_addr, ip4_address_t e_addr,
          if (is_identity_static_mapping (m))
            {
               /* *INDENT-OFF* */
-              pool_foreach (local, m->locals,
-              ({
+              pool_foreach (local, m->locals)
+               {
                 if (local->vrf_id == vrf_id)
                   return VNET_API_ERROR_VALUE_EXIST;
-              }));
+              }
               /* *INDENT-ON* */
              pool_get (m->locals, local);
              local->vrf_id = vrf_id;
              local->fib_index =
                fib_table_find_or_create_and_lock (FIB_PROTOCOL_IP4, vrf_id,
-                                                  nat_fib_src_low);
-             m_key.addr = m->local_addr;
-             m_key.port = m->local_port;
-             m_key.protocol = m->proto;
-             m_key.fib_index = local->fib_index;
-             kv.key = m_key.as_u64;
-             kv.value = m - sm->static_mappings;
+                                                  sm->fib_src_low);
+             init_nat_kv (&kv, m->local_addr, m->local_port,
+                          local->fib_index, m->proto,
+                          m - sm->static_mappings);
              clib_bihash_add_del_8_8 (&sm->static_mapping_by_local, &kv, 1);
              return 0;
            }
@@ -1045,22 +850,19 @@ snat_add_static_mapping (ip4_address_t l_addr, ip4_address_t e_addr,
       if (vrf_id != ~0)
        fib_index =
          fib_table_find_or_create_and_lock (FIB_PROTOCOL_IP4, vrf_id,
-                                            nat_fib_src_low);
+                                            sm->fib_src_low);
       /* If not specified use inside VRF id from SNAT plugin startup config */
       else
        {
          fib_index = sm->inside_fib_index;
          vrf_id = sm->inside_vrf_id;
-         fib_table_lock (fib_index, FIB_PROTOCOL_IP4, nat_fib_src_low);
+         fib_table_lock (fib_index, FIB_PROTOCOL_IP4, sm->fib_src_low);
        }
 
       if (!(out2in_only || identity_nat))
        {
-         m_key.addr = l_addr;
-         m_key.port = addr_only ? 0 : l_port;
-         m_key.protocol = addr_only ? 0 : proto;
-         m_key.fib_index = fib_index;
-         kv.key = m_key.as_u64;
+         init_nat_k (&kv, l_addr, addr_only ? 0 : l_port, fib_index,
+                     addr_only ? 0 : proto);
          if (!clib_bihash_search_8_8
              (&sm->static_mapping_by_local, &kv, &value))
            return VNET_API_ERROR_VALUE_EXIST;
@@ -1079,7 +881,7 @@ snat_add_static_mapping (ip4_address_t l_addr, ip4_address_t e_addr,
                  switch (proto)
                    {
 #define _(N, j, n, s) \
-                    case SNAT_PROTOCOL_##N: \
+                    case NAT_PROTOCOL_##N: \
                       if (a->busy_##n##_port_refcounts[e_port]) \
                         return VNET_API_ERROR_INVALID_VALUE; \
                       ++a->busy_##n##_port_refcounts[e_port]; \
@@ -1089,7 +891,7 @@ snat_add_static_mapping (ip4_address_t l_addr, ip4_address_t e_addr,
                           a->busy_##n##_ports_per_thread[get_thread_idx_by_port(e_port)]++; \
                         } \
                       break;
-                     foreach_snat_protocol
+                     foreach_nat_protocol
 #undef _
                    default:
                      nat_elog_info ("unknown protocol");
@@ -1128,6 +930,13 @@ snat_add_static_mapping (ip4_address_t l_addr, ip4_address_t e_addr,
       m->local_addr = l_addr;
       m->external_addr = e_addr;
       m->twice_nat = twice_nat;
+
+      if (twice_nat == TWICE_NAT && exact)
+       {
+         m->flags |= NAT_STATIC_MAPPING_FLAG_EXACT_ADDRESS;
+         m->pool_addr = pool_addr;
+       }
+
       if (out2in_only)
        m->flags |= NAT_STATIC_MAPPING_FLAG_OUT2IN_ONLY;
       if (addr_only)
@@ -1162,23 +971,19 @@ snat_add_static_mapping (ip4_address_t l_addr, ip4_address_t e_addr,
       else
        tsm = vec_elt_at_index (sm->per_thread_data, sm->num_workers);
 
-      m_key.addr = m->local_addr;
-      m_key.port = m->local_port;
-      m_key.protocol = m->proto;
-      m_key.fib_index = fib_index;
-      kv.key = m_key.as_u64;
-      kv.value = m - sm->static_mappings;
       if (!out2in_only)
-       clib_bihash_add_del_8_8 (&sm->static_mapping_by_local, &kv, 1);
+       {
+         init_nat_kv (&kv, m->local_addr, m->local_port, fib_index, m->proto,
+                      m - sm->static_mappings);
+         clib_bihash_add_del_8_8 (&sm->static_mapping_by_local, &kv, 1);
+       }
 
-      m_key.addr = m->external_addr;
-      m_key.port = m->external_port;
-      m_key.fib_index = 0;
-      kv.key = m_key.as_u64;
-      kv.value = m - sm->static_mappings;
+      init_nat_kv (&kv, m->external_addr, m->external_port, 0, m->proto,
+                  m - sm->static_mappings);
       clib_bihash_add_del_8_8 (&sm->static_mapping_by_external, &kv, 1);
 
       /* Delete dynamic sessions matching local address (+ local port) */
+      // TODO: based on type of NAT EI/ED
       if (!(sm->static_mapping_only))
        {
          u_key.addr = m->local_addr;
@@ -1204,9 +1009,7 @@ snat_add_static_mapping (ip4_address_t l_addr, ip4_address_t e_addr,
                      if (snat_is_session_static (s))
                        continue;
 
-                     if (!addr_only
-                         && (clib_net_to_host_u16 (s->in2out.port) !=
-                             m->local_port))
+                     if (!addr_only && s->in2out.port != m->local_port)
                        continue;
 
                      nat_free_session_data (sm, s,
@@ -1236,11 +1039,11 @@ snat_add_static_mapping (ip4_address_t l_addr, ip4_address_t e_addr,
            vrf_id = sm->inside_vrf_id;
 
           /* *INDENT-OFF* */
-          pool_foreach (local, m->locals,
-          ({
+          pool_foreach (local, m->locals)
+           {
            if (local->vrf_id == vrf_id)
               find = local - m->locals;
-         }));
+         }
           /* *INDENT-ON* */
          if (find == ~0)
            return VNET_API_ERROR_NO_SUCH_ENTRY;
@@ -1263,7 +1066,7 @@ snat_add_static_mapping (ip4_address_t l_addr, ip4_address_t e_addr,
                  switch (proto)
                    {
 #define _(N, j, n, s) \
-                    case SNAT_PROTOCOL_##N: \
+                    case NAT_PROTOCOL_##N: \
                       --a->busy_##n##_port_refcounts[e_port]; \
                       if (e_port > 1024) \
                         { \
@@ -1271,7 +1074,7 @@ snat_add_static_mapping (ip4_address_t l_addr, ip4_address_t e_addr,
                           a->busy_##n##_ports_per_thread[get_thread_idx_by_port(e_port)]--; \
                         } \
                       break;
-                     foreach_snat_protocol
+                     foreach_nat_protocol
 #undef _
                    default:
                      nat_elog_info ("unknown protocol");
@@ -1287,11 +1090,7 @@ snat_add_static_mapping (ip4_address_t l_addr, ip4_address_t e_addr,
       else
        tsm = vec_elt_at_index (sm->per_thread_data, sm->num_workers);
 
-      m_key.addr = m->local_addr;
-      m_key.port = m->local_port;
-      m_key.protocol = m->proto;
-      m_key.fib_index = fib_index;
-      kv.key = m_key.as_u64;
+      init_nat_k (&kv, m->local_addr, m->local_port, fib_index, m->proto);
       if (!out2in_only)
        clib_bihash_add_del_8_8 (&sm->static_mapping_by_local, &kv, 0);
 
@@ -1301,29 +1100,26 @@ snat_add_static_mapping (ip4_address_t l_addr, ip4_address_t e_addr,
        {
          if (sm->endpoint_dependent)
            {
-             snat_ed_static_mapping_del_sessions (sm, tsm, m->local_addr,
-                                                  m->local_port, m->proto,
-                                                  fib_index, addr_only,
-                                                  e_addr, e_port);
+             nat_ed_static_mapping_del_sessions (sm, tsm, m->local_addr,
+                                                 m->local_port, m->proto,
+                                                 fib_index, addr_only,
+                                                 e_addr, e_port);
            }
          else
            {
              u_key.addr = m->local_addr;
              u_key.fib_index = fib_index;
              kv.key = u_key.as_u64;
-             snat_static_mapping_del_sessions (sm, tsm, u_key, addr_only,
-                                               e_addr, e_port);
+             nat44_ei_static_mapping_del_sessions (sm, tsm, u_key, addr_only,
+                                                   e_addr, e_port);
            }
        }
 
-      fib_table_unlock (fib_index, FIB_PROTOCOL_IP4, nat_fib_src_low);
+      fib_table_unlock (fib_index, FIB_PROTOCOL_IP4, sm->fib_src_low);
       if (pool_elts (m->locals))
        return 0;
 
-      m_key.addr = m->external_addr;
-      m_key.port = m->external_port;
-      m_key.fib_index = 0;
-      kv.key = m_key.as_u64;
+      init_nat_k (&kv, m->external_addr, m->external_port, 0, m->proto);
       clib_bihash_add_del_8_8 (&sm->static_mapping_by_external, &kv, 0);
 
       vec_free (m->tag);
@@ -1337,53 +1133,73 @@ snat_add_static_mapping (ip4_address_t l_addr, ip4_address_t e_addr,
 
   /* Add/delete external address to FIB */
   /* *INDENT-OFF* */
-  pool_foreach (interface, sm->interfaces,
-  ({
+  pool_foreach (interface, sm->interfaces)
+   {
     if (nat_interface_is_inside(interface) || sm->out2in_dpo)
       continue;
 
     snat_add_del_addr_to_fib(&e_addr, 32, interface->sw_if_index, is_add);
     break;
-  }));
-  pool_foreach (interface, sm->output_feature_interfaces,
-  ({
+  }
+  pool_foreach (interface, sm->output_feature_interfaces)
+   {
     if (nat_interface_is_inside(interface) || sm->out2in_dpo)
       continue;
 
     snat_add_del_addr_to_fib(&e_addr, 32, interface->sw_if_index, is_add);
     break;
-  }));
+  }
   /* *INDENT-ON* */
 
   return 0;
 }
 
 int
-nat44_add_del_lb_static_mapping (ip4_address_t e_addr, u16 e_port,
-                                snat_protocol_t proto,
-                                nat44_lb_addr_port_t * locals, u8 is_add,
-                                twice_nat_type_t twice_nat, u8 out2in_only,
-                                u8 * tag, u32 affinity)
+snat_add_static_mapping (ip4_address_t l_addr, ip4_address_t e_addr,
+                        u16 l_port, u16 e_port, u32 vrf_id, int addr_only,
+                        u32 sw_if_index, nat_protocol_t proto, int is_add,
+                        twice_nat_type_t twice_nat, u8 out2in_only, u8 *tag,
+                        u8 identity_nat, ip4_address_t pool_addr, int exact)
 {
   snat_main_t *sm = &snat_main;
-  snat_static_mapping_t *m;
-  snat_session_key_t m_key;
-  clib_bihash_kv_8_8_t kv, value;
-  snat_address_t *a = 0;
-  int i;
+  int rv;
+
+  if (sm->endpoint_dependent)
+    {
+      rv = nat44_ed_add_del_static_mapping (
+       l_addr, e_addr, l_port, e_port, vrf_id, addr_only, sw_if_index, proto,
+       is_add, twice_nat, out2in_only, tag, identity_nat, pool_addr, exact);
+    }
+  else
+    {
+      rv = nat44_ei_add_del_static_mapping (
+       l_addr, e_addr, l_port, e_port, proto, sw_if_index, vrf_id, addr_only,
+       identity_nat, tag, is_add);
+    }
+  return rv;
+}
+
+int
+nat44_add_del_lb_static_mapping (ip4_address_t e_addr, u16 e_port,
+                                nat_protocol_t proto,
+                                nat44_lb_addr_port_t * locals, u8 is_add,
+                                twice_nat_type_t twice_nat, u8 out2in_only,
+                                u8 * tag, u32 affinity)
+{
+  snat_main_t *sm = &snat_main;
+  snat_static_mapping_t *m;
+  clib_bihash_kv_8_8_t kv, value;
+  snat_address_t *a = 0;
+  int i;
   nat44_lb_addr_port_t *local;
   snat_main_per_thread_data_t *tsm;
   snat_session_t *s;
   uword *bitmap = 0;
 
   if (!sm->endpoint_dependent)
-    return VNET_API_ERROR_FEATURE_DISABLED;
+    return VNET_API_ERROR_UNSUPPORTED;
 
-  m_key.addr = e_addr;
-  m_key.port = e_port;
-  m_key.protocol = proto;
-  m_key.fib_index = 0;
-  kv.key = m_key.as_u64;
+  init_nat_k (&kv, e_addr, e_port, 0, proto);
   if (clib_bihash_search_8_8 (&sm->static_mapping_by_external, &kv, &value))
     m = 0;
   else
@@ -1410,7 +1226,7 @@ nat44_add_del_lb_static_mapping (ip4_address_t e_addr, u16 e_port,
                  switch (proto)
                    {
 #define _(N, j, n, s) \
-                    case SNAT_PROTOCOL_##N: \
+                    case NAT_PROTOCOL_##N: \
                       if (a->busy_##n##_port_refcounts[e_port]) \
                         return VNET_API_ERROR_INVALID_VALUE; \
                       ++a->busy_##n##_port_refcounts[e_port]; \
@@ -1420,7 +1236,7 @@ nat44_add_del_lb_static_mapping (ip4_address_t e_addr, u16 e_port,
                           a->busy_##n##_ports_per_thread[get_thread_idx_by_port(e_port)]++; \
                         } \
                       break;
-                     foreach_snat_protocol
+                     foreach_nat_protocol
 #undef _
                    default:
                      nat_elog_info ("unknown protocol");
@@ -1452,32 +1268,25 @@ nat44_add_del_lb_static_mapping (ip4_address_t e_addr, u16 e_port,
       else
        m->affinity_per_service_list_head_index = ~0;
 
-      m_key.addr = m->external_addr;
-      m_key.port = m->external_port;
-      m_key.protocol = m->proto;
-      m_key.fib_index = 0;
-      kv.key = m_key.as_u64;
-      kv.value = m - sm->static_mappings;
+      init_nat_kv (&kv, m->external_addr, m->external_port, 0, m->proto,
+                  m - sm->static_mappings);
       if (clib_bihash_add_del_8_8 (&sm->static_mapping_by_external, &kv, 1))
        {
          nat_elog_err ("static_mapping_by_external key add failed");
          return VNET_API_ERROR_UNSPECIFIED;
        }
 
-      m_key.fib_index = m->fib_index;
       for (i = 0; i < vec_len (locals); i++)
        {
          locals[i].fib_index =
            fib_table_find_or_create_and_lock (FIB_PROTOCOL_IP4,
                                               locals[i].vrf_id,
-                                              nat_fib_src_low);
-         m_key.addr = locals[i].addr;
-         m_key.fib_index = locals[i].fib_index;
+                                              sm->fib_src_low);
          if (!out2in_only)
            {
-             m_key.port = locals[i].port;
-             kv.key = m_key.as_u64;
-             kv.value = m - sm->static_mappings;
+             init_nat_kv (&kv, locals[i].addr, locals[i].port,
+                          locals[i].fib_index, m->proto,
+                          m - sm->static_mappings);
              clib_bihash_add_del_8_8 (&sm->static_mapping_by_local, &kv, 1);
            }
          locals[i].prefix = (i == 0) ? locals[i].probability :
@@ -1500,10 +1309,10 @@ nat44_add_del_lb_static_mapping (ip4_address_t e_addr, u16 e_port,
       if (sm->num_workers > 1)
        {
           /* *INDENT-OFF* */
-          clib_bitmap_foreach (i, bitmap,
-            ({
+          clib_bitmap_foreach (i, bitmap)
+             {
                vec_add1(m->workers, i);
-            }));
+            }
           /* *INDENT-ON* */
        }
     }
@@ -1526,7 +1335,7 @@ nat44_add_del_lb_static_mapping (ip4_address_t e_addr, u16 e_port,
                  switch (proto)
                    {
 #define _(N, j, n, s) \
-                    case SNAT_PROTOCOL_##N: \
+                    case NAT_PROTOCOL_##N: \
                       --a->busy_##n##_port_refcounts[e_port]; \
                       if (e_port > 1024) \
                         { \
@@ -1534,7 +1343,7 @@ nat44_add_del_lb_static_mapping (ip4_address_t e_addr, u16 e_port,
                           a->busy_##n##_ports_per_thread[get_thread_idx_by_port(e_port)]--; \
                         } \
                       break;
-                     foreach_snat_protocol
+                     foreach_nat_protocol
 #undef _
                    default:
                      nat_elog_info ("unknown protocol");
@@ -1545,11 +1354,7 @@ nat44_add_del_lb_static_mapping (ip4_address_t e_addr, u16 e_port,
            }
        }
 
-      m_key.addr = m->external_addr;
-      m_key.port = m->external_port;
-      m_key.protocol = m->proto;
-      m_key.fib_index = 0;
-      kv.key = m_key.as_u64;
+      init_nat_k (&kv, m->external_addr, m->external_port, 0, m->proto);
       if (clib_bihash_add_del_8_8 (&sm->static_mapping_by_external, &kv, 0))
        {
          nat_elog_err ("static_mapping_by_external key del failed");
@@ -1557,16 +1362,13 @@ nat44_add_del_lb_static_mapping (ip4_address_t e_addr, u16 e_port,
        }
 
       /* *INDENT-OFF* */
-      pool_foreach (local, m->locals,
-      ({
+      pool_foreach (local, m->locals)
+      {
           fib_table_unlock (local->fib_index, FIB_PROTOCOL_IP4,
-                            nat_fib_src_low);
-          m_key.addr = local->addr;
+                            sm->fib_src_low);
           if (!out2in_only)
             {
-              m_key.port = local->port;
-              m_key.fib_index = local->fib_index;
-              kv.key = m_key.as_u64;
+init_nat_k(&              kv, local->addr, local->port, local->fib_index, m->proto);
               if (clib_bihash_add_del_8_8(&sm->static_mapping_by_local, &kv, 0))
                 {
                   nat_elog_err ("static_mapping_by_local key del failed");
@@ -1586,18 +1388,18 @@ nat44_add_del_lb_static_mapping (ip4_address_t e_addr, u16 e_port,
             tsm = vec_elt_at_index (sm->per_thread_data, sm->num_workers);
 
           /* Delete sessions */
-          pool_foreach (s, tsm->sessions, {
+          pool_foreach (s, tsm->sessions) {
             if (!(is_lb_session (s)))
               continue;
 
             if ((s->in2out.addr.as_u32 != local->addr.as_u32) ||
-                (clib_net_to_host_u16 (s->in2out.port) != local->port))
+                s->in2out.port != local->port)
               continue;
 
             nat_free_session_data (sm, s, tsm - sm->per_thread_data, 0);
-            nat44_ed_delete_session (sm, s, tsm - sm->per_thread_data, 1);
-          });
-      }));
+            nat_ed_session_delete (sm, s, tsm - sm->per_thread_data, 1);
+          }
+      }
       /* *INDENT-ON* */
       if (m->affinity)
        nat_affinity_flush_service (m->affinity_per_service_list_head_index);
@@ -1614,12 +1416,11 @@ nat44_add_del_lb_static_mapping (ip4_address_t e_addr, u16 e_port,
 int
 nat44_lb_static_mapping_add_del_local (ip4_address_t e_addr, u16 e_port,
                                       ip4_address_t l_addr, u16 l_port,
-                                      snat_protocol_t proto, u32 vrf_id,
+                                      nat_protocol_t proto, u32 vrf_id,
                                       u8 probability, u8 is_add)
 {
   snat_main_t *sm = &snat_main;
   snat_static_mapping_t *m = 0;
-  snat_session_key_t m_key;
   clib_bihash_kv_8_8_t kv, value;
   nat44_lb_addr_port_t *local, *prev_local, *match_local = 0;
   snat_main_per_thread_data_t *tsm;
@@ -1631,11 +1432,7 @@ nat44_lb_static_mapping_add_del_local (ip4_address_t e_addr, u16 e_port,
   if (!sm->endpoint_dependent)
     return VNET_API_ERROR_FEATURE_DISABLED;
 
-  m_key.addr = e_addr;
-  m_key.port = e_port;
-  m_key.protocol = proto;
-  m_key.fib_index = 0;
-  kv.key = m_key.as_u64;
+  init_nat_k (&kv, e_addr, e_port, 0, proto);
   if (!clib_bihash_search_8_8 (&sm->static_mapping_by_external, &kv, &value))
     m = pool_elt_at_index (sm->static_mappings, value.value);
 
@@ -1646,15 +1443,15 @@ nat44_lb_static_mapping_add_del_local (ip4_address_t e_addr, u16 e_port,
     return VNET_API_ERROR_INVALID_VALUE;
 
   /* *INDENT-OFF* */
-  pool_foreach (local, m->locals,
-  ({
+  pool_foreach (local, m->locals)
+   {
     if ((local->addr.as_u32 == l_addr.as_u32) && (local->port == l_port) &&
         (local->vrf_id == vrf_id))
       {
         match_local = local;
         break;
       }
-  }));
+  }
   /* *INDENT-ON* */
 
   if (is_add)
@@ -1670,15 +1467,12 @@ nat44_lb_static_mapping_add_del_local (ip4_address_t e_addr, u16 e_port,
       local->vrf_id = vrf_id;
       local->fib_index =
        fib_table_find_or_create_and_lock (FIB_PROTOCOL_IP4, vrf_id,
-                                          nat_fib_src_low);
+                                          sm->fib_src_low);
 
       if (!is_out2in_only_static_mapping (m))
        {
-         m_key.addr = l_addr;
-         m_key.port = l_port;
-         m_key.fib_index = local->fib_index;
-         kv.key = m_key.as_u64;
-         kv.value = m - sm->static_mappings;
+         init_nat_kv (&kv, l_addr, l_port, local->fib_index, proto,
+                      m - sm->static_mappings);
          if (clib_bihash_add_del_8_8 (&sm->static_mapping_by_local, &kv, 1))
            nat_elog_err ("static_mapping_by_local key add failed");
        }
@@ -1692,14 +1486,11 @@ nat44_lb_static_mapping_add_del_local (ip4_address_t e_addr, u16 e_port,
        return VNET_API_ERROR_UNSPECIFIED;
 
       fib_table_unlock (match_local->fib_index, FIB_PROTOCOL_IP4,
-                       nat_fib_src_low);
+                       sm->fib_src_low);
 
       if (!is_out2in_only_static_mapping (m))
        {
-         m_key.addr = l_addr;
-         m_key.port = l_port;
-         m_key.fib_index = match_local->fib_index;
-         kv.key = m_key.as_u64;
+         init_nat_k (&kv, l_addr, l_port, match_local->fib_index, proto);
          if (clib_bihash_add_del_8_8 (&sm->static_mapping_by_local, &kv, 0))
            nat_elog_err ("static_mapping_by_local key del failed");
        }
@@ -1718,17 +1509,17 @@ nat44_lb_static_mapping_add_del_local (ip4_address_t e_addr, u16 e_port,
 
       /* Delete sessions */
       /* *INDENT-OFF* */
-      pool_foreach (s, tsm->sessions, {
+      pool_foreach (s, tsm->sessions) {
         if (!(is_lb_session (s)))
           continue;
 
         if ((s->in2out.addr.as_u32 != match_local->addr.as_u32) ||
-            (clib_net_to_host_u16 (s->in2out.port) != match_local->port))
+            s->in2out.port != match_local->port)
           continue;
 
         nat_free_session_data (sm, s, tsm - sm->per_thread_data, 0);
-        nat44_ed_delete_session (sm, s, tsm - sm->per_thread_data, 1);
-      });
+        nat_ed_session_delete (sm, s, tsm - sm->per_thread_data, 1);
+      }
       /* *INDENT-ON* */
 
       pool_put (m->locals, match_local);
@@ -1737,8 +1528,8 @@ nat44_lb_static_mapping_add_del_local (ip4_address_t e_addr, u16 e_port,
   vec_free (m->workers);
 
   /* *INDENT-OFF* */
-  pool_foreach (local, m->locals,
-  ({
+  pool_foreach (local, m->locals)
+   {
     vec_add1 (locals, local - m->locals);
     if (sm->num_workers > 1)
       {
@@ -1748,7 +1539,7 @@ nat44_lb_static_mapping_add_del_local (ip4_address_t e_addr, u16 e_port,
                                   sm->worker_in2out_cb (&ip, local->fib_index, 0),
                                   1);
       }
-  }));
+  }
   /* *INDENT-ON* */
 
   ASSERT (vec_len (locals) > 1);
@@ -1766,7 +1557,7 @@ nat44_lb_static_mapping_add_del_local (ip4_address_t e_addr, u16 e_port,
   if (sm->num_workers > 1)
     {
       /* *INDENT-OFF* */
-      clib_bitmap_foreach (i, bitmap, ({ vec_add1(m->workers, i); }));
+      clib_bitmap_foreach (i, bitmap)  { vec_add1(m->workers, i); }
       /* *INDENT-ON* */
     }
 
@@ -1797,20 +1588,29 @@ snat_del_address (snat_main_t * sm, ip4_address_t addr, u8 delete_sm,
        }
     }
   if (!a)
-    return VNET_API_ERROR_NO_SUCH_ENTRY;
+    {
+      nat_log_err ("no such address");
+      return VNET_API_ERROR_NO_SUCH_ENTRY;
+    }
 
   if (delete_sm)
     {
+      ip4_address_t pool_addr = { 0 };
       /* *INDENT-OFF* */
-      pool_foreach (m, sm->static_mappings,
-      ({
+      pool_foreach (m, sm->static_mappings)
+       {
           if (m->external_addr.as_u32 == addr.as_u32)
             (void) snat_add_static_mapping (m->local_addr, m->external_addr,
                                             m->local_port, m->external_port,
-                                            m->vrf_id, is_addr_only_static_mapping(m), ~0,
-                                            m->proto, 0, m->twice_nat,
-                                            is_out2in_only_static_mapping(m), m->tag, is_identity_static_mapping(m));
-      }));
+                                            m->vrf_id,
+                                            is_addr_only_static_mapping(m), ~0,
+                                            m->proto, 0 /* is_add */,
+                                            m->twice_nat,
+                                            is_out2in_only_static_mapping(m),
+                                            m->tag,
+                                            is_identity_static_mapping(m),
+                                            pool_addr, 0);
+      }
       /* *INDENT-ON* */
     }
   else
@@ -1818,50 +1618,53 @@ snat_del_address (snat_main_t * sm, ip4_address_t addr, u8 delete_sm,
       /* Check if address is used in some static mapping */
       if (is_snat_address_used_in_static_mapping (sm, addr))
        {
-         nat_elog_notice ("address used in static mapping");
+         nat_log_err ("address used in static mapping");
          return VNET_API_ERROR_UNSPECIFIED;
        }
     }
 
   if (a->fib_index != ~0)
-    fib_table_unlock (a->fib_index, FIB_PROTOCOL_IP4, nat_fib_src_low);
+    fib_table_unlock (a->fib_index, FIB_PROTOCOL_IP4, sm->fib_src_low);
 
   /* Delete sessions using address */
   if (a->busy_tcp_ports || a->busy_udp_ports || a->busy_icmp_ports)
     {
-      /* *INDENT-OFF* */
       vec_foreach (tsm, sm->per_thread_data)
-        {
-          pool_foreach (ses, tsm->sessions, ({
-            if (ses->out2in.addr.as_u32 == addr.as_u32)
-              {
-                nat_free_session_data (sm, ses, tsm - sm->per_thread_data, 0);
-                vec_add1 (ses_to_be_removed, ses - tsm->sessions);
-              }
-          }));
+      {
+        /* *INDENT-OFF* */
+        pool_foreach (ses, tsm->sessions)  {
+          if (ses->out2in.addr.as_u32 == addr.as_u32)
+            {
+              nat_free_session_data (sm, ses, tsm - sm->per_thread_data, 0);
+              vec_add1 (ses_to_be_removed, ses - tsm->sessions);
+            }
+        }
+        /* *INDENT-ON* */
 
-         if (sm->endpoint_dependent){
-             vec_foreach (ses_index, ses_to_be_removed)
-               {
-                 ses = pool_elt_at_index (tsm->sessions, ses_index[0]);
-                 nat44_ed_delete_session (sm, ses, tsm - sm->per_thread_data, 1);
-               }
-         }else{
-             vec_foreach (ses_index, ses_to_be_removed)
-               {
-                 ses = pool_elt_at_index (tsm->sessions, ses_index[0]);
-                 nat44_delete_session (sm, ses, tsm - sm->per_thread_data);
-               }
+       if (sm->endpoint_dependent)
+         {
+           vec_foreach (ses_index, ses_to_be_removed)
+           {
+             ses = pool_elt_at_index (tsm->sessions, ses_index[0]);
+             nat_ed_session_delete (sm, ses, tsm - sm->per_thread_data, 1);
+           }
+         }
+       else
+         {
+           vec_foreach (ses_index, ses_to_be_removed)
+           {
+             ses = pool_elt_at_index (tsm->sessions, ses_index[0]);
+             nat44_delete_session (sm, ses, tsm - sm->per_thread_data);
+           }
          }
 
-          vec_free (ses_to_be_removed);
-        }
-      /* *INDENT-ON* */
+       vec_free (ses_to_be_removed);
+      }
     }
 
 #define _(N, i, n, s) \
   vec_free (a->busy_##n##_ports_per_thread);
-  foreach_snat_protocol
+  foreach_nat_protocol
 #undef _
     if (twice_nat)
     {
@@ -1873,27 +1676,120 @@ snat_del_address (snat_main_t * sm, ip4_address_t addr, u8 delete_sm,
 
   /* Delete external address from FIB */
   /* *INDENT-OFF* */
-  pool_foreach (interface, sm->interfaces,
-  ({
+  pool_foreach (interface, sm->interfaces)
+   {
     if (nat_interface_is_inside(interface) || sm->out2in_dpo)
       continue;
 
     snat_add_del_addr_to_fib(&addr, 32, interface->sw_if_index, 0);
     break;
-  }));
-  pool_foreach (interface, sm->output_feature_interfaces,
-  ({
+  }
+  pool_foreach (interface, sm->output_feature_interfaces)
+   {
     if (nat_interface_is_inside(interface) || sm->out2in_dpo)
       continue;
 
     snat_add_del_addr_to_fib(&addr, 32, interface->sw_if_index, 0);
     break;
-  }));
+  }
   /* *INDENT-ON* */
 
   return 0;
 }
 
+static void
+nat_validate_counters (snat_main_t * sm, u32 sw_if_index)
+{
+#define _(x)                                                                  \
+  vlib_validate_simple_counter (&sm->counters.fastpath.in2out.x,              \
+                                sw_if_index);                                 \
+  vlib_zero_simple_counter (&sm->counters.fastpath.in2out.x, sw_if_index);    \
+  vlib_validate_simple_counter (&sm->counters.fastpath.out2in.x,              \
+                                sw_if_index);                                 \
+  vlib_zero_simple_counter (&sm->counters.fastpath.out2in.x, sw_if_index);    \
+  vlib_validate_simple_counter (&sm->counters.slowpath.in2out.x,              \
+                                sw_if_index);                                 \
+  vlib_zero_simple_counter (&sm->counters.slowpath.in2out.x, sw_if_index);    \
+  vlib_validate_simple_counter (&sm->counters.slowpath.out2in.x,              \
+                                sw_if_index);                                 \
+  vlib_zero_simple_counter (&sm->counters.slowpath.out2in.x, sw_if_index);    \
+  vlib_validate_simple_counter (&sm->counters.fastpath.in2out_ed.x,           \
+                                sw_if_index);                                 \
+  vlib_zero_simple_counter (&sm->counters.fastpath.in2out_ed.x, sw_if_index); \
+  vlib_validate_simple_counter (&sm->counters.fastpath.out2in_ed.x,           \
+                                sw_if_index);                                 \
+  vlib_zero_simple_counter (&sm->counters.fastpath.out2in_ed.x, sw_if_index); \
+  vlib_validate_simple_counter (&sm->counters.slowpath.in2out_ed.x,           \
+                                sw_if_index);                                 \
+  vlib_zero_simple_counter (&sm->counters.slowpath.in2out_ed.x, sw_if_index); \
+  vlib_validate_simple_counter (&sm->counters.slowpath.out2in_ed.x,           \
+                                sw_if_index);                                 \
+  vlib_zero_simple_counter (&sm->counters.slowpath.out2in_ed.x, sw_if_index);
+  foreach_nat_counter;
+#undef _
+  vlib_validate_simple_counter (&sm->counters.hairpinning, sw_if_index);
+  vlib_zero_simple_counter (&sm->counters.hairpinning, sw_if_index);
+}
+
+void
+expire_per_vrf_sessions (u32 fib_index)
+{
+  per_vrf_sessions_t *per_vrf_sessions;
+  snat_main_per_thread_data_t *tsm;
+  snat_main_t *sm = &snat_main;
+
+  /* *INDENT-OFF* */
+  vec_foreach (tsm, sm->per_thread_data)
+    {
+      vec_foreach (per_vrf_sessions, tsm->per_vrf_sessions_vec)
+        {
+          if ((per_vrf_sessions->rx_fib_index == fib_index) ||
+              (per_vrf_sessions->tx_fib_index == fib_index))
+            {
+              per_vrf_sessions->expired = 1;
+            }
+        }
+    }
+  /* *INDENT-ON* */
+}
+
+void
+update_per_vrf_sessions_vec (u32 fib_index, int is_del)
+{
+  snat_main_t *sm = &snat_main;
+  nat_fib_t *fib;
+
+  // we don't care if it is outside/inside fib
+  // we just care about their ref_count
+  // if it reaches 0 sessions should expire
+  // because the fib isn't valid for NAT anymore
+
+  vec_foreach (fib, sm->fibs)
+  {
+    if (fib->fib_index == fib_index)
+      {
+       if (is_del)
+         {
+           fib->ref_count--;
+           if (!fib->ref_count)
+             {
+               vec_del1 (sm->fibs, fib - sm->fibs);
+               expire_per_vrf_sessions (fib_index);
+             }
+           return;
+         }
+       else
+         fib->ref_count++;
+      }
+  }
+  if (!is_del)
+    {
+      vec_add2 (sm->fibs, fib, 1);
+      fib->ref_count = 1;
+      fib->fib_index = fib_index;
+    }
+}
+
 int
 snat_interface_add_del (u32 sw_if_index, u8 is_inside, int is_del)
 {
@@ -1902,32 +1798,41 @@ snat_interface_add_del (u32 sw_if_index, u8 is_inside, int is_del)
   const char *feature_name, *del_feature_name;
   snat_address_t *ap;
   snat_static_mapping_t *m;
-  snat_det_map_t *dm;
   nat_outside_fib_t *outside_fib;
   u32 fib_index = fib_table_get_index_for_sw_if_index (FIB_PROTOCOL_IP4,
                                                       sw_if_index);
 
+  if (!sm->enabled)
+    {
+      nat_log_err ("nat44 is disabled");
+      return VNET_API_ERROR_UNSUPPORTED;
+    }
+
   if (sm->out2in_dpo && !is_inside)
-    return VNET_API_ERROR_UNSUPPORTED;
+    {
+      nat_log_err ("error unsupported");
+      return VNET_API_ERROR_UNSUPPORTED;
+    }
 
   /* *INDENT-OFF* */
-  pool_foreach (i, sm->output_feature_interfaces,
-  ({
+  pool_foreach (i, sm->output_feature_interfaces)
+   {
     if (i->sw_if_index == sw_if_index)
-      return VNET_API_ERROR_VALUE_EXIST;
-  }));
+      {
+        nat_log_err ("error interface already configured");
+        return VNET_API_ERROR_VALUE_EXIST;
+      }
+  }
   /* *INDENT-ON* */
 
   if (sm->static_mapping_only && !(sm->static_mapping_connection_tracking))
     feature_name = is_inside ? "nat44-in2out-fast" : "nat44-out2in-fast";
   else
     {
-      if (sm->num_workers > 1 && !sm->deterministic)
+      if (sm->num_workers > 1)
        feature_name =
          is_inside ? "nat44-in2out-worker-handoff" :
          "nat44-out2in-worker-handoff";
-      else if (sm->deterministic)
-       feature_name = is_inside ? "nat44-det-in2out" : "nat44-det-out2in";
       else if (sm->endpoint_dependent)
        {
          feature_name = is_inside ? "nat-pre-in2out" : "nat-pre-out2in";
@@ -1936,13 +1841,16 @@ snat_interface_add_del (u32 sw_if_index, u8 is_inside, int is_del)
        feature_name = is_inside ? "nat44-in2out" : "nat44-out2in";
     }
 
-  if (sm->fq_in2out_index == ~0 && !sm->deterministic && sm->num_workers > 1)
+  if (sm->fq_in2out_index == ~0 && sm->num_workers > 1)
     sm->fq_in2out_index =
-      vlib_frame_queue_main_init (sm->handoff_in2out_index, NAT_FQ_NELTS);
+      vlib_frame_queue_main_init (sm->in2out_node_index, NAT_FQ_NELTS);
 
-  if (sm->fq_out2in_index == ~0 && !sm->deterministic && sm->num_workers > 1)
+  if (sm->fq_out2in_index == ~0 && sm->num_workers > 1)
     sm->fq_out2in_index =
-      vlib_frame_queue_main_init (sm->handoff_out2in_index, NAT_FQ_NELTS);
+      vlib_frame_queue_main_init (sm->out2in_node_index, NAT_FQ_NELTS);
+
+  if (sm->endpoint_dependent)
+    update_per_vrf_sessions_vec (fib_index, is_del);
 
   if (!is_inside)
     {
@@ -1970,10 +1878,11 @@ snat_interface_add_del (u32 sw_if_index, u8 is_inside, int is_del)
          outside_fib->fib_index = fib_index;
        }
     }
+
 feature_set:
   /* *INDENT-OFF* */
-  pool_foreach (i, sm->interfaces,
-  ({
+  pool_foreach (i, sm->interfaces)
+   {
     if (i->sw_if_index == sw_if_index)
       {
         if (is_del)
@@ -1985,18 +1894,12 @@ feature_set:
                 else
                   i->flags &= ~NAT_INTERFACE_FLAG_IS_OUTSIDE;
 
-                if (sm->num_workers > 1 && !sm->deterministic)
+                if (sm->num_workers > 1)
                   {
                     del_feature_name = "nat44-handoff-classify";
                     feature_name = !is_inside ?  "nat44-in2out-worker-handoff" :
                                                  "nat44-out2in-worker-handoff";
                   }
-                else if (sm->deterministic)
-                  {
-                    del_feature_name = "nat44-det-classify";
-                    feature_name = !is_inside ?  "nat44-det-in2out" :
-                                                 "nat44-det-out2in";
-                  }
                 else if (sm->endpoint_dependent)
                   {
                     del_feature_name = "nat44-ed-classify";
@@ -2018,18 +1921,14 @@ feature_set:
                                              sw_if_index, 1, 0, 0);
                 if (!is_inside)
                   {
-                    if (sm->endpoint_dependent)
-                      vnet_feature_enable_disable ("ip4-local",
-                                                   "nat44-ed-hairpinning",
-                                                   sw_if_index, 1, 0, 0);
-                    else if (!sm->deterministic)
-                      vnet_feature_enable_disable ("ip4-local",
-                                                   "nat44-hairpinning",
-                                                   sw_if_index, 1, 0, 0);
-                  }
-              }
-            else
-              {
+                   if (!sm->endpoint_dependent)
+                     vnet_feature_enable_disable ("ip4-local",
+                                                  "nat44-hairpinning",
+                                                  sw_if_index, 1, 0, 0);
+                 }
+             }
+           else
+             {
                int rv = ip4_sv_reass_enable_disable_with_refcnt (sw_if_index, 0);
                if (rv)
                  return rv;
@@ -2038,47 +1937,38 @@ feature_set:
                 pool_put (sm->interfaces, i);
                 if (is_inside)
                   {
-                    if (sm->endpoint_dependent)
-                      vnet_feature_enable_disable ("ip4-local",
-                                                   "nat44-ed-hairpinning",
-                                                   sw_if_index, 0, 0, 0);
-                    else if (!sm->deterministic)
-                      vnet_feature_enable_disable ("ip4-local",
-                                                   "nat44-hairpinning",
-                                                   sw_if_index, 0, 0, 0);
-                  }
-              }
-          }
-        else
-          {
-            if ((nat_interface_is_inside(i) && is_inside) ||
-                (nat_interface_is_outside(i) && !is_inside))
-              return 0;
-
-            if (sm->num_workers > 1 && !sm->deterministic)
-              {
-                del_feature_name = !is_inside ?  "nat44-in2out-worker-handoff" :
-                                                 "nat44-out2in-worker-handoff";
-                feature_name = "nat44-handoff-classify";
-              }
-            else if (sm->deterministic)
-              {
-                del_feature_name = !is_inside ?  "nat44-det-in2out" :
-                                                 "nat44-det-out2in";
-                feature_name = "nat44-det-classify";
-              }
-            else if (sm->endpoint_dependent)
-              {
-                del_feature_name = !is_inside ?  "nat-pre-in2out" :
-                                                 "nat-pre-out2in";
+                   if (!sm->endpoint_dependent)
+                     vnet_feature_enable_disable ("ip4-local",
+                                                  "nat44-hairpinning",
+                                                  sw_if_index, 0, 0, 0);
+                 }
+             }
+         }
+       else
+         {
+           if ((nat_interface_is_inside (i) && is_inside) ||
+               (nat_interface_is_outside (i) && !is_inside))
+             return 0;
 
-                feature_name = "nat44-ed-classify";
-              }
-            else
-              {
-                del_feature_name = !is_inside ?  "nat44-in2out" : "nat44-out2in";
-                feature_name = "nat44-classify";
-              }
+           if (sm->num_workers > 1)
+             {
+               del_feature_name = !is_inside ? "nat44-in2out-worker-handoff" :
+                                               "nat44-out2in-worker-handoff";
+               feature_name = "nat44-handoff-classify";
+             }
+           else if (sm->endpoint_dependent)
+             {
+               del_feature_name =
+                 !is_inside ? "nat-pre-in2out" : "nat-pre-out2in";
+
+               feature_name = "nat44-ed-classify";
+             }
+           else
+             {
+               del_feature_name =
+                 !is_inside ? "nat44-in2out" : "nat44-out2in";
+               feature_name = "nat44-classify";
+             }
 
            int rv = ip4_sv_reass_enable_disable_with_refcnt (sw_if_index, 1);
            if (rv)
@@ -2089,27 +1979,29 @@ feature_set:
                                          sw_if_index, 1, 0, 0);
             if (!is_inside)
               {
-                if (sm->endpoint_dependent)
-                  vnet_feature_enable_disable ("ip4-local", "nat44-ed-hairpinning",
-                                               sw_if_index, 0, 0, 0);
-                else if (!sm->deterministic)
-                  vnet_feature_enable_disable ("ip4-local", "nat44-hairpinning",
-                                               sw_if_index, 0, 0, 0);
-              }
-            goto set_flags;
-          }
+               if (!sm->endpoint_dependent)
+                 vnet_feature_enable_disable (
+                   "ip4-local", "nat44-hairpinning", sw_if_index, 0, 0, 0);
+             }
+           goto set_flags;
+         }
 
-        goto fib;
+       goto fib;
       }
-  }));
+  }
   /* *INDENT-ON* */
 
   if (is_del)
-    return VNET_API_ERROR_NO_SUCH_ENTRY;
+    {
+      nat_log_err ("error interface couldn't be found");
+      return VNET_API_ERROR_NO_SUCH_ENTRY;
+    }
 
   pool_get (sm->interfaces, i);
   i->sw_if_index = sw_if_index;
   i->flags = 0;
+  nat_validate_counters (sm, sw_if_index);
+
   vnet_feature_enable_disable ("ip4-unicast", feature_name, sw_if_index, 1, 0,
                               0);
 
@@ -2119,10 +2011,7 @@ feature_set:
 
   if (is_inside && !sm->out2in_dpo)
     {
-      if (sm->endpoint_dependent)
-       vnet_feature_enable_disable ("ip4-local", "nat44-ed-hairpinning",
-                                    sw_if_index, 1, 0, 0);
-      else if (!sm->deterministic)
+      if (!sm->endpoint_dependent)
        vnet_feature_enable_disable ("ip4-local", "nat44-hairpinning",
                                     sw_if_index, 1, 0, 0);
     }
@@ -2142,18 +2031,13 @@ fib:
   vec_foreach (ap, sm->addresses)
     snat_add_del_addr_to_fib(&ap->addr, 32, sw_if_index, !is_del);
 
-  pool_foreach (m, sm->static_mappings,
-  ({
+  pool_foreach (m, sm->static_mappings)
+   {
     if (!(is_addr_only_static_mapping(m)) || (m->local_addr.as_u32 == m->external_addr.as_u32))
       continue;
 
     snat_add_del_addr_to_fib(&m->external_addr, 32, sw_if_index, !is_del);
-  }));
-
-  pool_foreach (dm, sm->det_maps,
-  ({
-    snat_add_del_addr_to_fib(&dm->out_addr, dm->out_plen, sw_if_index, !is_del);
-  }));
+  }
   /* *INDENT-ON* */
 
   return 0;
@@ -2171,19 +2055,32 @@ snat_interface_add_del_output_feature (u32 sw_if_index,
   u32 fib_index = fib_table_get_index_for_sw_if_index (FIB_PROTOCOL_IP4,
                                                       sw_if_index);
 
+  if (!sm->enabled)
+    {
+      nat_log_err ("nat44 is disabled");
+      return VNET_API_ERROR_UNSUPPORTED;
+    }
 
-  if (sm->deterministic ||
-      (sm->static_mapping_only && !(sm->static_mapping_connection_tracking)))
-    return VNET_API_ERROR_UNSUPPORTED;
+  if (sm->static_mapping_only && !(sm->static_mapping_connection_tracking))
+    {
+      nat_log_err ("error unsupported");
+      return VNET_API_ERROR_UNSUPPORTED;
+    }
 
   /* *INDENT-OFF* */
-  pool_foreach (i, sm->interfaces,
-  ({
+  pool_foreach (i, sm->interfaces)
+   {
     if (i->sw_if_index == sw_if_index)
-      return VNET_API_ERROR_VALUE_EXIST;
-  }));
+      {
+        nat_log_err ("error interface already configured");
+        return VNET_API_ERROR_VALUE_EXIST;
+      }
+  }
   /* *INDENT-ON* */
 
+  if (sm->endpoint_dependent)
+    update_per_vrf_sessions_vec (fib_index, is_del);
+
   if (!is_inside)
     {
       /* *INDENT-OFF* */
@@ -2225,10 +2122,6 @@ feature_set:
                                                            !is_del);
          if (rv)
            return rv;
-         vnet_feature_enable_disable ("ip4-unicast", "nat44-ed-hairpin-dst",
-                                      sw_if_index, !is_del, 0, 0);
-         vnet_feature_enable_disable ("ip4-output", "nat44-ed-hairpin-src",
-                                      sw_if_index, !is_del, 0, 0);
        }
       else
        {
@@ -2280,7 +2173,7 @@ feature_set:
            return rv;
          vnet_feature_enable_disable ("ip4-unicast", "nat-pre-out2in",
                                       sw_if_index, !is_del, 0, 0);
-         vnet_feature_enable_disable ("ip4-output", "nat44-ed-in2out-output",
+         vnet_feature_enable_disable ("ip4-output", "nat-pre-in2out-output",
                                       sw_if_index, !is_del, 0, 0);
        }
       else
@@ -2304,15 +2197,15 @@ feature_set:
 fq:
   if (sm->fq_in2out_output_index == ~0 && sm->num_workers > 1)
     sm->fq_in2out_output_index =
-      vlib_frame_queue_main_init (sm->handoff_in2out_output_index, 0);
+      vlib_frame_queue_main_init (sm->in2out_output_node_index, 0);
 
   if (sm->fq_out2in_index == ~0 && sm->num_workers > 1)
     sm->fq_out2in_index =
-      vlib_frame_queue_main_init (sm->handoff_out2in_index, 0);
+      vlib_frame_queue_main_init (sm->out2in_node_index, 0);
 
   /* *INDENT-OFF* */
-  pool_foreach (i, sm->output_feature_interfaces,
-  ({
+  pool_foreach (i, sm->output_feature_interfaces)
+   {
     if (i->sw_if_index == sw_if_index)
       {
         if (is_del)
@@ -2322,15 +2215,19 @@ fq:
 
         goto fib;
       }
-  }));
+  }
   /* *INDENT-ON* */
 
   if (is_del)
-    return VNET_API_ERROR_NO_SUCH_ENTRY;
+    {
+      nat_log_err ("error interface couldn't be found");
+      return VNET_API_ERROR_NO_SUCH_ENTRY;
+    }
 
   pool_get (sm->output_feature_interfaces, i);
   i->sw_if_index = sw_if_index;
   i->flags = 0;
+  nat_validate_counters (sm, sw_if_index);
   if (is_inside)
     i->flags |= NAT_INTERFACE_FLAG_IS_INSIDE;
   else
@@ -2345,13 +2242,13 @@ fib:
   vec_foreach (ap, sm->addresses)
     snat_add_del_addr_to_fib(&ap->addr, 32, sw_if_index, !is_del);
 
-  pool_foreach (m, sm->static_mappings,
-  ({
+  pool_foreach (m, sm->static_mappings)
+   {
     if (!((is_addr_only_static_mapping(m)))  || (m->local_addr.as_u32 == m->external_addr.as_u32))
       continue;
 
     snat_add_del_addr_to_fib(&m->external_addr, 32, sw_if_index, !is_del);
-  }));
+  }
   /* *INDENT-ON* */
 
   return 0;
@@ -2371,23 +2268,23 @@ snat_set_workers (uword * bitmap)
 
   vec_free (sm->workers);
   /* *INDENT-OFF* */
-  clib_bitmap_foreach (i, bitmap,
-    ({
+  clib_bitmap_foreach (i, bitmap)
+    {
       vec_add1(sm->workers, i);
       sm->per_thread_data[sm->first_worker_index + i].snat_thread_index = j;
       sm->per_thread_data[sm->first_worker_index + i].thread_index = i;
       j++;
-    }));
+    }
   /* *INDENT-ON* */
 
   sm->port_per_thread = (0xffff - 1024) / _vec_len (sm->workers);
-  sm->num_snat_thread = _vec_len (sm->workers);
 
   return 0;
 }
 
 static void
-snat_update_outside_fib (u32 sw_if_index, u32 new_fib_index,
+snat_update_outside_fib (ip4_main_t * im, uword opaque,
+                        u32 sw_if_index, u32 new_fib_index,
                         u32 old_fib_index)
 {
   snat_main_t *sm = &snat_main;
@@ -2396,32 +2293,32 @@ snat_update_outside_fib (u32 sw_if_index, u32 new_fib_index,
   u8 is_add = 1;
   u8 match = 0;
 
-  if (new_fib_index == old_fib_index)
-    return;
-
-  if (!vec_len (sm->outside_fibs))
-    return;
+  if (!sm->enabled || (new_fib_index == old_fib_index)
+      || (!vec_len (sm->outside_fibs)))
+    {
+      return;
+    }
 
   /* *INDENT-OFF* */
-  pool_foreach (i, sm->interfaces,
-    ({
+  pool_foreach (i, sm->interfaces)
+     {
       if (i->sw_if_index == sw_if_index)
         {
           if (!(nat_interface_is_outside (i)))
            return;
           match = 1;
         }
-    }));
+    }
 
-  pool_foreach (i, sm->output_feature_interfaces,
-    ({
+  pool_foreach (i, sm->output_feature_interfaces)
+     {
       if (i->sw_if_index == sw_if_index)
         {
           if (!(nat_interface_is_outside (i)))
            return;
           match = 1;
         }
-    }));
+    }
   /* *INDENT-ON* */
 
   if (!match)
@@ -2457,12 +2354,9 @@ snat_update_outside_fib (u32 sw_if_index, u32 new_fib_index,
 }
 
 static void
-snat_ip4_table_bind (ip4_main_t * im,
-                    uword opaque,
-                    u32 sw_if_index, u32 new_fib_index, u32 old_fib_index)
-{
-  snat_update_outside_fib (sw_if_index, new_fib_index, old_fib_index);
-}
+snat_update_outside_fib (ip4_main_t * im, uword opaque,
+                        u32 sw_if_index, u32 new_fib_index,
+                        u32 old_fib_index);
 
 static void
 snat_ip4_add_del_interface_address_cb (ip4_main_t * im,
@@ -2480,106 +2374,204 @@ nat_ip4_add_del_addr_only_sm_cb (ip4_main_t * im,
                                 u32 address_length,
                                 u32 if_address_index, u32 is_delete);
 
-static int
-nat_alloc_addr_and_port_default (snat_address_t * addresses,
-                                u32 fib_index,
-                                u32 thread_index,
-                                snat_session_key_t * k,
-                                u16 port_per_thread, u32 snat_thread_index);
+void
+test_key_calc_split ()
+{
+  ip4_address_t l_addr;
+  l_addr.as_u8[0] = 1;
+  l_addr.as_u8[1] = 1;
+  l_addr.as_u8[2] = 1;
+  l_addr.as_u8[3] = 1;
+  ip4_address_t r_addr;
+  r_addr.as_u8[0] = 2;
+  r_addr.as_u8[1] = 2;
+  r_addr.as_u8[2] = 2;
+  r_addr.as_u8[3] = 2;
+  u16 l_port = 40001;
+  u16 r_port = 40301;
+  u8 proto = 9;
+  u32 fib_index = 9000001;
+  u32 thread_index = 3000000001;
+  u32 session_index = 3000000221;
+  clib_bihash_kv_16_8_t kv;
+  init_ed_kv (&kv, l_addr, l_port, r_addr, r_port, fib_index, proto,
+             thread_index, session_index);
+  ip4_address_t l_addr2;
+  ip4_address_t r_addr2;
+  clib_memset (&l_addr2, 0, sizeof (l_addr2));
+  clib_memset (&r_addr2, 0, sizeof (r_addr2));
+  u16 l_port2 = 0;
+  u16 r_port2 = 0;
+  u8 proto2 = 0;
+  u32 fib_index2 = 0;
+  split_ed_kv (&kv, &l_addr2, &r_addr2, &proto2, &fib_index2, &l_port2,
+              &r_port2);
+  ASSERT (l_addr.as_u32 == l_addr2.as_u32);
+  ASSERT (r_addr.as_u32 == r_addr2.as_u32);
+  ASSERT (l_port == l_port2);
+  ASSERT (r_port == r_port2);
+  ASSERT (proto == proto2);
+  ASSERT (fib_index == fib_index2);
+  ASSERT (thread_index == ed_value_get_thread_index (&kv));
+  ASSERT (session_index == ed_value_get_session_index (&kv));
+
+  fib_index = 7001;
+  proto = 5;
+  nat_protocol_t proto3 = ~0;
+  u64 key = calc_nat_key (l_addr, l_port, fib_index, proto);
+  split_nat_key (key, &l_addr2, &l_port2, &fib_index2, &proto3);
+  ASSERT (l_addr.as_u32 == l_addr2.as_u32);
+  ASSERT (l_port == l_port2);
+  ASSERT (proto == proto3);
+  ASSERT (fib_index == fib_index2);
+}
 
 static clib_error_t *
-snat_init (vlib_main_t * vm)
+nat_ip_table_add_del (vnet_main_t * vnm, u32 table_id, u32 is_add)
 {
   snat_main_t *sm = &snat_main;
-  clib_error_t *error = 0;
-  ip4_main_t *im = &ip4_main;
-  ip_lookup_main_t *lm = &im->lookup_main;
-  uword *p;
-  vlib_thread_registration_t *tr;
-  vlib_thread_main_t *tm = vlib_get_thread_main ();
-  uword *bitmap = 0;
-  u32 i;
-  ip4_add_del_interface_address_callback_t cb4;
+  u32 fib_index;
+
+  if (sm->endpoint_dependent)
+    {
+      // TODO: consider removing all NAT interfaces
+      if (!is_add)
+       {
+         fib_index = ip4_fib_index_from_table_id (table_id);
+         if (fib_index != ~0)
+           expire_per_vrf_sessions (fib_index);
+       }
+    }
+  return 0;
+}
+
+VNET_IP_TABLE_ADD_DEL_FUNCTION (nat_ip_table_add_del);
+
+void
+nat44_set_node_indexes (snat_main_t * sm, vlib_main_t * vm)
+{
   vlib_node_t *node;
 
-  sm->vlib_main = vm;
-  sm->vnet_main = vnet_get_main ();
-  sm->ip4_main = im;
-  sm->ip4_lookup_main = lm;
-  sm->api_main = vlibapi_get_main ();
-  sm->first_worker_index = 0;
-  sm->num_workers = 0;
-  sm->num_snat_thread = 1;
-  sm->workers = 0;
-  sm->port_per_thread = 0xffff - 1024;
-  sm->fq_in2out_index = ~0;
-  sm->fq_in2out_output_index = ~0;
-  sm->fq_out2in_index = ~0;
+  node = vlib_get_node_by_name (vm, (u8 *) "nat44-out2in");
+  sm->ei_out2in_node_index = node->index;
+  node = vlib_get_node_by_name (vm, (u8 *) "nat44-in2out");
+  sm->ei_in2out_node_index = node->index;
+  node = vlib_get_node_by_name (vm, (u8 *) "nat44-in2out-output");
+  sm->ei_in2out_output_node_index = node->index;
 
-  sm->alloc_addr_and_port = nat_alloc_addr_and_port_default;
-  sm->addr_and_port_alloc_alg = NAT_ADDR_AND_PORT_ALLOC_ALG_DEFAULT;
-  sm->forwarding_enabled = 0;
-  sm->log_class = vlib_log_register_class ("nat", 0);
-  sm->log_level = SNAT_LOG_ERROR;
-  sm->mss_clamping = 0;
+  node = vlib_get_node_by_name (vm, (u8 *) "nat44-ed-out2in");
+  sm->ed_out2in_node_index = node->index;
+  node = vlib_get_node_by_name (vm, (u8 *) "nat44-ed-in2out");
+  sm->ed_in2out_node_index = node->index;
+  node = vlib_get_node_by_name (vm, (u8 *) "nat44-ed-in2out-output");
+  sm->ed_in2out_output_node_index = node->index;
 
   node = vlib_get_node_by_name (vm, (u8 *) "error-drop");
   sm->error_node_index = node->index;
-
   node = vlib_get_node_by_name (vm, (u8 *) "nat-pre-in2out");
   sm->pre_in2out_node_index = node->index;
   node = vlib_get_node_by_name (vm, (u8 *) "nat-pre-out2in");
   sm->pre_out2in_node_index = node->index;
-
   node = vlib_get_node_by_name (vm, (u8 *) "nat-pre-in2out");
   sm->pre_in2out_node_index = node->index;
-
   node = vlib_get_node_by_name (vm, (u8 *) "nat-pre-out2in");
   sm->pre_out2in_node_index = node->index;
-
-  node = vlib_get_node_by_name (vm, (u8 *) "nat44-in2out");
-  sm->in2out_node_index = node->index;
-  node = vlib_get_node_by_name (vm, (u8 *) "nat44-in2out-output");
-  sm->in2out_output_node_index = node->index;
   node = vlib_get_node_by_name (vm, (u8 *) "nat44-in2out-fast");
   sm->in2out_fast_node_index = node->index;
   node = vlib_get_node_by_name (vm, (u8 *) "nat44-in2out-slowpath");
   sm->in2out_slowpath_node_index = node->index;
   node = vlib_get_node_by_name (vm, (u8 *) "nat44-in2out-output-slowpath");
   sm->in2out_slowpath_output_node_index = node->index;
-
-  node = vlib_get_node_by_name (vm, (u8 *) "nat44-ed-in2out");
-  sm->ed_in2out_node_index = node->index;
   node = vlib_get_node_by_name (vm, (u8 *) "nat44-ed-in2out-slowpath");
   sm->ed_in2out_slowpath_node_index = node->index;
-
-  node = vlib_get_node_by_name (vm, (u8 *) "nat44-out2in");
-  sm->out2in_node_index = node->index;
   node = vlib_get_node_by_name (vm, (u8 *) "nat44-out2in-fast");
   sm->out2in_fast_node_index = node->index;
-
-  node = vlib_get_node_by_name (vm, (u8 *) "nat44-ed-out2in");
-  sm->ed_out2in_node_index = node->index;
   node = vlib_get_node_by_name (vm, (u8 *) "nat44-ed-out2in-slowpath");
   sm->ed_out2in_slowpath_node_index = node->index;
-
-  node = vlib_get_node_by_name (vm, (u8 *) "nat44-det-in2out");
-  sm->det_in2out_node_index = node->index;
-  node = vlib_get_node_by_name (vm, (u8 *) "nat44-det-out2in");
-  sm->det_out2in_node_index = node->index;
-
   node = vlib_get_node_by_name (vm, (u8 *) "nat44-hairpinning");
   sm->hairpinning_node_index = node->index;
   node = vlib_get_node_by_name (vm, (u8 *) "nat44-hairpin-dst");
   sm->hairpin_dst_node_index = node->index;
   node = vlib_get_node_by_name (vm, (u8 *) "nat44-hairpin-src");
   sm->hairpin_src_node_index = node->index;
-  node = vlib_get_node_by_name (vm, (u8 *) "nat44-ed-hairpinning");
-  sm->ed_hairpinning_node_index = node->index;
-  node = vlib_get_node_by_name (vm, (u8 *) "nat44-ed-hairpin-dst");
-  sm->ed_hairpin_dst_node_index = node->index;
-  node = vlib_get_node_by_name (vm, (u8 *) "nat44-ed-hairpin-src");
-  sm->ed_hairpin_src_node_index = node->index;
+}
+
+#define nat_init_simple_counter(c, n, sn) \
+do                                        \
+  {                                       \
+    c.name = n;                           \
+    c.stat_segment_name = sn;             \
+    vlib_validate_simple_counter (&c, 0); \
+    vlib_zero_simple_counter (&c, 0);     \
+  } while (0);
+
+static clib_error_t *
+nat_init (vlib_main_t * vm)
+{
+  snat_main_t *sm = &snat_main;
+  vlib_thread_main_t *tm = vlib_get_thread_main ();
+  vlib_thread_registration_t *tr;
+  ip4_add_del_interface_address_callback_t cbi = { 0 };
+  ip4_table_bind_callback_t cbt = { 0 };
+  u32 i, num_threads = 0;
+  uword *p, *bitmap = 0;
+
+  clib_memset (sm, 0, sizeof (*sm));
+
+  // required
+  sm->vnet_main = vnet_get_main ();
+  // convenience
+  sm->ip4_main = &ip4_main;
+  sm->api_main = vlibapi_get_main ();
+  sm->ip4_lookup_main = &ip4_main.lookup_main;
+
+  // frame queue indices used for handoff
+  sm->fq_out2in_index = ~0;
+  sm->fq_in2out_index = ~0;
+  sm->fq_in2out_output_index = ~0;
+
+  sm->log_level = SNAT_LOG_ERROR;
+
+  nat44_set_node_indexes (sm, vm);
+  sm->log_class = vlib_log_register_class ("nat", 0);
+  nat_ipfix_logging_init (vm);
+
+  nat_init_simple_counter (sm->total_users, "total-users",
+                          "/nat44/total-users");
+  nat_init_simple_counter (sm->total_sessions, "total-sessions",
+                          "/nat44/total-sessions");
+  nat_init_simple_counter (sm->user_limit_reached, "user-limit-reached",
+                          "/nat44/user-limit-reached");
+
+#define _(x)                                            \
+  sm->counters.fastpath.in2out.x.name = #x;             \
+  sm->counters.fastpath.in2out.x.stat_segment_name =    \
+      "/nat44/in2out/fastpath/" #x;                     \
+  sm->counters.slowpath.in2out.x.name = #x;             \
+  sm->counters.slowpath.in2out.x.stat_segment_name =    \
+      "/nat44/in2out/slowpath/" #x;                     \
+  sm->counters.fastpath.out2in.x.name = #x;             \
+  sm->counters.fastpath.out2in.x.stat_segment_name =    \
+      "/nat44/out2in/fastpath/" #x;                     \
+  sm->counters.slowpath.out2in.x.name = #x;             \
+  sm->counters.slowpath.out2in.x.stat_segment_name =    \
+      "/nat44/out2in/slowpath/" #x;                     \
+  sm->counters.fastpath.in2out_ed.x.name = #x;          \
+  sm->counters.fastpath.in2out_ed.x.stat_segment_name = \
+      "/nat44/ed/in2out/fastpath/" #x;                  \
+  sm->counters.slowpath.in2out_ed.x.name = #x;          \
+  sm->counters.slowpath.in2out_ed.x.stat_segment_name = \
+      "/nat44/ed/in2out/slowpath/" #x;                  \
+  sm->counters.fastpath.out2in_ed.x.name = #x;          \
+  sm->counters.fastpath.out2in_ed.x.stat_segment_name = \
+      "/nat44/ed/out2in/fastpath/" #x;                  \
+  sm->counters.slowpath.out2in_ed.x.name = #x;          \
+  sm->counters.slowpath.out2in_ed.x.stat_segment_name = \
+      "/nat44/ed/out2in/slowpath/" #x;
+  foreach_nat_counter;
+#undef _
+  sm->counters.hairpinning.name = "hairpinning";
+  sm->counters.hairpinning.stat_segment_name = "/nat44/hairpinning";
 
   p = hash_get_mem (tm->thread_registrations_by_name, "workers");
   if (p)
@@ -2591,88 +2583,290 @@ snat_init (vlib_main_t * vm)
          sm->first_worker_index = tr->first_index;
        }
     }
-
-  vec_validate (sm->per_thread_data, tm->n_vlib_mains - 1);
+  num_threads = tm->n_vlib_mains - 1;
+  sm->port_per_thread = 0xffff - 1024;
+  vec_validate (sm->per_thread_data, num_threads);
 
   /* Use all available workers by default */
   if (sm->num_workers > 1)
     {
+
       for (i = 0; i < sm->num_workers; i++)
        bitmap = clib_bitmap_set (bitmap, i, 1);
       snat_set_workers (bitmap);
       clib_bitmap_free (bitmap);
     }
   else
-    {
-      sm->per_thread_data[0].snat_thread_index = 0;
-    }
+    sm->per_thread_data[0].snat_thread_index = 0;
+
+  /* callbacks to call when interface address changes. */
+  cbi.function = snat_ip4_add_del_interface_address_cb;
+  vec_add1 (sm->ip4_main->add_del_interface_address_callbacks, cbi);
+  cbi.function = nat_ip4_add_del_addr_only_sm_cb;
+  vec_add1 (sm->ip4_main->add_del_interface_address_callbacks, cbi);
+
+  /* callbacks to call when interface to table biding changes */
+  cbt.function = snat_update_outside_fib;
+  vec_add1 (sm->ip4_main->table_bind_callbacks, cbt);
+
+  sm->fib_src_low =
+    fib_source_allocate ("nat-low", FIB_SOURCE_PRIORITY_LOW,
+                        FIB_SOURCE_BH_SIMPLE);
+  sm->fib_src_hi =
+    fib_source_allocate ("nat-hi", FIB_SOURCE_PRIORITY_HI,
+                        FIB_SOURCE_BH_SIMPLE);
+
+  /* used only by out2in-dpo feature */
+  nat_dpo_module_init ();
 
-  error = snat_api_init (vm, sm);
-  if (error)
-    return error;
+  nat_affinity_init (vm);
+  nat_ha_init (vm, sm->num_workers, num_threads);
 
-  /* Set up the interface address add/del callback */
-  cb4.function = snat_ip4_add_del_interface_address_cb;
-  cb4.function_opaque = 0;
+  test_key_calc_split ();
+  return nat44_api_hookup (vm);
+}
 
-  vec_add1 (im->add_del_interface_address_callbacks, cb4);
+VLIB_INIT_FUNCTION (nat_init);
 
-  cb4.function = nat_ip4_add_del_addr_only_sm_cb;
-  cb4.function_opaque = 0;
+static int
+nat44_ed_plugin_enable (nat44_config_t c)
+{
+  snat_main_t *sm = &snat_main;
+
+  if (c.static_mapping_only && !c.connection_tracking)
+    {
+      nat_log_err ("unsupported combination of configuration");
+      return 1;
+    }
 
-  vec_add1 (im->add_del_interface_address_callbacks, cb4);
+  // nat44 feature configuration
+  sm->endpoint_dependent = c.endpoint_dependent;
+  sm->static_mapping_only = c.static_mapping_only;
+  sm->static_mapping_connection_tracking = c.connection_tracking;
 
-  nat_dpo_module_init ();
+  // EI only feature (could break ED)
+  sm->out2in_dpo = c.out2in_dpo;
+
+  sm->forwarding_enabled = 0;
+  sm->mss_clamping = 0;
+  sm->pat = (!c.static_mapping_only ||
+            (c.static_mapping_only && c.connection_tracking));
+
+  if (!c.users)
+    c.users = 1024;
+
+  // EI only feature (could break ED)
+  sm->max_users_per_thread = c.users;
+  sm->user_buckets = nat_calc_bihash_buckets (c.users);
+
+  if (!c.sessions)
+    c.sessions = 10 * 1024;
+
+  sm->max_translations_per_thread = c.sessions;
+  sm->translation_buckets = nat_calc_bihash_buckets (c.sessions);
+
+  // ED only feature
+  vec_add1 (sm->max_translations_per_fib, sm->max_translations_per_thread);
+
+  // EI only feature (could break ED)
+  sm->max_translations_per_user
+    = c.user_sessions ? c.user_sessions : sm->max_translations_per_thread;
+
+  sm->inside_vrf_id = c.inside_vrf;
+  sm->inside_fib_index =
+    fib_table_find_or_create_and_lock
+    (FIB_PROTOCOL_IP4, c.inside_vrf, sm->fib_src_hi);
+
+  sm->outside_vrf_id = c.outside_vrf;
+  sm->outside_fib_index = fib_table_find_or_create_and_lock (
+    FIB_PROTOCOL_IP4, c.outside_vrf, sm->fib_src_hi);
+
+  sm->worker_in2out_cb = nat44_ed_get_worker_in2out_cb;
+  sm->worker_out2in_cb = nat44_ed_get_worker_out2in_cb;
+
+  sm->in2out_node_index = sm->ed_in2out_node_index;
+  sm->out2in_node_index = sm->ed_out2in_node_index;
+
+  sm->in2out_output_node_index = sm->ed_in2out_output_node_index;
+
+  if (sm->pat)
+    {
+      sm->icmp_match_in2out_cb = NULL;
+      sm->icmp_match_out2in_cb = NULL;
+    }
+  else
+    {
+      sm->icmp_match_in2out_cb = icmp_match_in2out_fast;
+      sm->icmp_match_out2in_cb = icmp_match_out2in_fast;
+    }
+
+  nat44_ed_db_init (sm->max_translations_per_thread, sm->translation_buckets,
+                   sm->user_buckets);
+
+  nat_affinity_enable ();
 
-  /* Init counters */
-  sm->total_users.name = "total-users";
-  sm->total_users.stat_segment_name = "/nat44/total-users";
-  vlib_validate_simple_counter (&sm->total_users, 0);
+  nat_reset_timeouts (&sm->timeouts);
+
+  // TODO: function for reset counters
   vlib_zero_simple_counter (&sm->total_users, 0);
-  sm->total_sessions.name = "total-sessions";
-  sm->total_sessions.stat_segment_name = "/nat44/total-sessions";
-  vlib_validate_simple_counter (&sm->total_sessions, 0);
   vlib_zero_simple_counter (&sm->total_sessions, 0);
+  vlib_zero_simple_counter (&sm->user_limit_reached, 0);
+
+  sm->enabled = 1;
+  sm->rconfig = c;
 
-  /* Init IPFIX logging */
-  snat_ipfix_logging_init (vm);
+  return 0;
+}
 
-  /* Init NAT64 */
-  error = nat64_init (vm);
-  if (error)
-    return error;
+int
+nat44_plugin_enable (nat44_config_t c)
+{
+  fail_if_enabled ();
 
-  nat66_init (vm);
+  // c.static_mapping_only + c.connection_tracking
+  //  - supported in NAT EI & NAT ED
+  // c.out2in_dpo, c.static_mapping_only
+  //  - supported in NAT EI
 
-  ip4_table_bind_callback_t cbt4 = {
-    .function = snat_ip4_table_bind,
+  if (c.endpoint_dependent)
+    {
+      if (c.out2in_dpo || c.users || c.user_sessions)
+       {
+         nat_log_err ("unsupported combination of configuration");
+         return 1;
+       }
+      return nat44_ed_plugin_enable (c);
+    }
+
+  // separation:
+  // for now just copy variables
+
+  nat44_ei_config_t ei_c = {
+    .inside_vrf = c.inside_vrf,
+    .outside_vrf = c.outside_vrf,
+    .users = c.users,
+    .sessions = c.sessions,
+    .user_sessions = c.user_sessions,
+    .out2in_dpo = c.out2in_dpo,
+    .static_mapping_only = c.static_mapping_only,
+    .connection_tracking = c.connection_tracking,
   };
-  vec_add1 (ip4_main.table_bind_callbacks, cbt4);
 
-  nat_fib_src_hi = fib_source_allocate ("nat-hi",
-                                       FIB_SOURCE_PRIORITY_HI,
-                                       FIB_SOURCE_BH_SIMPLE);
-  nat_fib_src_low = fib_source_allocate ("nat-low",
-                                        FIB_SOURCE_PRIORITY_LOW,
-                                        FIB_SOURCE_BH_SIMPLE);
+  return nat44_ei_plugin_enable (ei_c);
+}
+
+void
+nat44_addresses_free (snat_address_t ** addresses)
+{
+  snat_address_t *ap;
+  /* *INDENT-OFF* */
+  vec_foreach (ap, *addresses)
+    {
+    #define _(N, i, n, s) \
+      vec_free (ap->busy_##n##_ports_per_thread);
+      foreach_nat_protocol
+    #undef _
+    }
+  /* *INDENT-ON* */
+  vec_free (*addresses);
+  *addresses = 0;
+}
+
+static int
+nat44_ed_plugin_disable ()
+{
+  snat_main_t *sm = &snat_main;
+  snat_interface_t *i, *vec;
+  int error = 0;
+
+  // first unregister all nodes from interfaces
+  vec = vec_dup (sm->interfaces);
+  /* *INDENT-OFF* */
+  vec_foreach (i, vec)
+    {
+      if (nat_interface_is_inside(i))
+        error = snat_interface_add_del (i->sw_if_index, 1, 1);
+      if (nat_interface_is_outside(i))
+        error = snat_interface_add_del (i->sw_if_index, 0, 1);
+
+      if (error)
+        {
+          nat_log_err ("error occurred while removing interface %u",
+                       i->sw_if_index);
+        }
+    }
+  /* *INDENT-ON* */
+  vec_free (vec);
+  sm->interfaces = 0;
+
+  vec = vec_dup (sm->output_feature_interfaces);
+  /* *INDENT-OFF* */
+  vec_foreach (i, vec)
+    {
+      if (nat_interface_is_inside(i))
+        error = snat_interface_add_del_output_feature (i->sw_if_index, 1, 1);
+      if (nat_interface_is_outside(i))
+        error = snat_interface_add_del_output_feature (i->sw_if_index, 0, 1);
+
+      if (error)
+        {
+          nat_log_err ("error occurred while removing interface %u",
+                       i->sw_if_index);
+        }
+    }
+  /* *INDENT-ON* */
+  vec_free (vec);
+  sm->output_feature_interfaces = 0;
+
+  vec_free (sm->max_translations_per_fib);
+
+  nat44_ed_db_free ();
 
-  return error;
+  nat44_addresses_free (&sm->addresses);
+  nat44_addresses_free (&sm->twice_nat_addresses);
+
+
+  vec_free (sm->to_resolve);
+  vec_free (sm->auto_add_sw_if_indices);
+  vec_free (sm->auto_add_sw_if_indices_twice_nat);
+
+  sm->to_resolve = 0;
+  sm->auto_add_sw_if_indices = 0;
+  sm->auto_add_sw_if_indices_twice_nat = 0;
+
+  sm->forwarding_enabled = 0;
+
+  sm->enabled = 0;
+  clib_memset (&sm->rconfig, 0, sizeof (sm->rconfig));
+
+  return 0;
 }
 
-VLIB_INIT_FUNCTION (snat_init);
+int
+nat44_plugin_disable ()
+{
+  snat_main_t *sm = &snat_main;
+
+  fail_if_disabled ();
+
+  if (sm->endpoint_dependent)
+    return nat44_ed_plugin_disable ();
+  return nat44_ei_plugin_disable ();
+}
 
 void
-snat_free_outside_address_and_port (snat_address_t * addresses,
-                                   u32 thread_index, snat_session_key_t * k)
+snat_free_outside_address_and_port (snat_address_t *addresses,
+                                   u32 thread_index, ip4_address_t *addr,
+                                   u16 port, nat_protocol_t protocol)
 {
   snat_address_t *a;
   u32 address_index;
-  u16 port_host_byte_order = clib_net_to_host_u16 (k->port);
+  u16 port_host_byte_order = clib_net_to_host_u16 (port);
 
   for (address_index = 0; address_index < vec_len (addresses);
        address_index++)
     {
-      if (addresses[address_index].addr.as_u32 == k->addr.as_u32)
+      if (addresses[address_index].addr.as_u32 == addr->as_u32)
        break;
     }
 
@@ -2680,16 +2874,16 @@ snat_free_outside_address_and_port (snat_address_t * addresses,
 
   a = addresses + address_index;
 
-  switch (k->protocol)
+  switch (protocol)
     {
 #define _(N, i, n, s) \
-    case SNAT_PROTOCOL_##N: \
+    case NAT_PROTOCOL_##N: \
       ASSERT (a->busy_##n##_port_refcounts[port_host_byte_order] >= 1); \
       --a->busy_##n##_port_refcounts[port_host_byte_order]; \
       a->busy_##n##_ports--; \
       a->busy_##n##_ports_per_thread[thread_index]--; \
       break;
-      foreach_snat_protocol
+      foreach_nat_protocol
 #undef _
     default:
       nat_elog_info ("unknown protocol");
@@ -2697,32 +2891,33 @@ snat_free_outside_address_and_port (snat_address_t * addresses,
     }
 }
 
-static int
-nat_set_outside_address_and_port (snat_address_t * addresses,
-                                 u32 thread_index, snat_session_key_t * k)
+int
+nat_set_outside_address_and_port (snat_address_t *addresses, u32 thread_index,
+                                 ip4_address_t addr, u16 port,
+                                 nat_protocol_t protocol)
 {
   snat_address_t *a = 0;
   u32 address_index;
-  u16 port_host_byte_order = clib_net_to_host_u16 (k->port);
+  u16 port_host_byte_order = clib_net_to_host_u16 (port);
 
   for (address_index = 0; address_index < vec_len (addresses);
        address_index++)
     {
-      if (addresses[address_index].addr.as_u32 != k->addr.as_u32)
+      if (addresses[address_index].addr.as_u32 != addr.as_u32)
        continue;
 
       a = addresses + address_index;
-      switch (k->protocol)
+      switch (protocol)
        {
 #define _(N, j, n, s) \
-        case SNAT_PROTOCOL_##N: \
+        case NAT_PROTOCOL_##N: \
           if (a->busy_##n##_port_refcounts[port_host_byte_order]) \
             return VNET_API_ERROR_INSTANCE_IN_USE; \
          ++a->busy_##n##_port_refcounts[port_host_byte_order]; \
           a->busy_##n##_ports_per_thread[thread_index]++; \
           a->busy_##n##_ports++; \
           return 0;
-         foreach_snat_protocol
+         foreach_nat_protocol
 #undef _
        default:
          nat_elog_info ("unknown protocol");
@@ -2735,43 +2930,50 @@ nat_set_outside_address_and_port (snat_address_t * addresses,
 
 int
 snat_static_mapping_match (snat_main_t * sm,
-                          snat_session_key_t match,
-                          snat_session_key_t * mapping,
+                          ip4_address_t match_addr,
+                          u16 match_port,
+                          u32 match_fib_index,
+                          nat_protocol_t match_protocol,
+                          ip4_address_t * mapping_addr,
+                          u16 * mapping_port,
+                          u32 * mapping_fib_index,
                           u8 by_external,
                           u8 * is_addr_only,
                           twice_nat_type_t * twice_nat,
                           lb_nat_type_t * lb, ip4_address_t * ext_host_addr,
-                          u8 * is_identity_nat)
+                          u8 * is_identity_nat, snat_static_mapping_t ** out)
 {
   clib_bihash_kv_8_8_t kv, value;
+  clib_bihash_8_8_t *mapping_hash;
   snat_static_mapping_t *m;
-  snat_session_key_t m_key;
-  clib_bihash_8_8_t *mapping_hash = &sm->static_mapping_by_local;
   u32 rand, lo = 0, hi, mid, *tmp = 0, i;
-  u8 backend_index;
   nat44_lb_addr_port_t *local;
+  u8 backend_index;
 
-  m_key.fib_index = match.fib_index;
-  if (by_external)
+  if (!by_external)
     {
-      mapping_hash = &sm->static_mapping_by_external;
-      m_key.fib_index = 0;
+      mapping_hash = &sm->static_mapping_by_local;
+      init_nat_k (&kv, match_addr, match_port, match_fib_index,
+                 match_protocol);
+      if (clib_bihash_search_8_8 (mapping_hash, &kv, &value))
+       {
+         /* Try address only mapping */
+         init_nat_k (&kv, match_addr, 0, match_fib_index, 0);
+         if (clib_bihash_search_8_8 (mapping_hash, &kv, &value))
+           return 1;
+       }
     }
-
-  m_key.addr = match.addr;
-  m_key.port = clib_net_to_host_u16 (match.port);
-  m_key.protocol = match.protocol;
-
-  kv.key = m_key.as_u64;
-
-  if (clib_bihash_search_8_8 (mapping_hash, &kv, &value))
+  else
     {
-      /* Try address only mapping */
-      m_key.port = 0;
-      m_key.protocol = 0;
-      kv.key = m_key.as_u64;
+      mapping_hash = &sm->static_mapping_by_external;
+      init_nat_k (&kv, match_addr, match_port, 0, match_protocol);
       if (clib_bihash_search_8_8 (mapping_hash, &kv, &value))
-       return 1;
+       {
+         /* Try address only mapping */
+         init_nat_k (&kv, match_addr, 0, 0, 0);
+         if (clib_bihash_search_8_8 (mapping_hash, &kv, &value))
+           return 1;
+       }
     }
 
   m = pool_elt_at_index (sm->static_mappings, value.value);
@@ -2783,15 +2985,15 @@ snat_static_mapping_match (snat_main_t * sm,
          if (PREDICT_FALSE (lb != 0))
            *lb = m->affinity ? AFFINITY_LB_NAT : LB_NAT;
          if (m->affinity && !nat_affinity_find_and_lock (ext_host_addr[0],
-                                                         match.addr,
-                                                         match.protocol,
-                                                         match.port,
+                                                         match_addr,
+                                                         match_protocol,
+                                                         match_port,
                                                          &backend_index))
            {
              local = pool_elt_at_index (m->locals, backend_index);
-             mapping->addr = local->addr;
-             mapping->port = clib_host_to_net_u16 (local->port);
-             mapping->fib_index = local->fib_index;
+             *mapping_addr = local->addr;
+             *mapping_port = local->port;
+             *mapping_fib_index = local->fib_index;
              goto end;
            }
          // pick locals matching this worker
@@ -2799,8 +3001,8 @@ snat_static_mapping_match (snat_main_t * sm,
            {
              u32 thread_index = vlib_get_thread_index ();
               /* *INDENT-OFF* */
-              pool_foreach_index (i, m->locals,
-              ({
+              pool_foreach_index (i, m->locals)
+               {
                 local = pool_elt_at_index (m->locals, i);
 
                 ip4_header_t ip = {
@@ -2812,17 +3014,17 @@ snat_static_mapping_match (snat_main_t * sm,
                   {
                     vec_add1 (tmp, i);
                   }
-              }));
+              }
               /* *INDENT-ON* */
              ASSERT (vec_len (tmp) != 0);
            }
          else
            {
               /* *INDENT-OFF* */
-              pool_foreach_index (i, m->locals,
-              ({
+              pool_foreach_index (i, m->locals)
+               {
                 vec_add1 (tmp, i);
-              }));
+              }
               /* *INDENT-ON* */
            }
          hi = vec_len (tmp) - 1;
@@ -2837,13 +3039,13 @@ snat_static_mapping_match (snat_main_t * sm,
          local = pool_elt_at_index (m->locals, tmp[lo]);
          if (!(local->prefix >= rand))
            return 1;
-         mapping->addr = local->addr;
-         mapping->port = clib_host_to_net_u16 (local->port);
-         mapping->fib_index = local->fib_index;
+         *mapping_addr = local->addr;
+         *mapping_port = local->port;
+         *mapping_fib_index = local->fib_index;
          if (m->affinity)
            {
-             if (nat_affinity_create_and_lock (ext_host_addr[0], match.addr,
-                                               match.protocol, match.port,
+             if (nat_affinity_create_and_lock (ext_host_addr[0], match_addr,
+                                               match_protocol, match_port,
                                                tmp[lo], m->affinity,
                                                m->affinity_per_service_list_head_index))
                nat_elog_info ("create affinity record failed");
@@ -2854,21 +3056,20 @@ snat_static_mapping_match (snat_main_t * sm,
        {
          if (PREDICT_FALSE (lb != 0))
            *lb = NO_LB_NAT;
-         mapping->fib_index = m->fib_index;
-         mapping->addr = m->local_addr;
+         *mapping_fib_index = m->fib_index;
+         *mapping_addr = m->local_addr;
          /* Address only mapping doesn't change port */
-         mapping->port = is_addr_only_static_mapping (m) ? match.port
-           : clib_host_to_net_u16 (m->local_port);
+         *mapping_port = is_addr_only_static_mapping (m) ? match_port
+           : m->local_port;
        }
-      mapping->protocol = m->proto;
     }
   else
     {
-      mapping->addr = m->external_addr;
+      *mapping_addr = m->external_addr;
       /* Address only mapping doesn't change port */
-      mapping->port = is_addr_only_static_mapping (m) ? match.port
-       : clib_host_to_net_u16 (m->external_port);
-      mapping->fib_index = sm->outside_fib_index;
+      *mapping_port = is_addr_only_static_mapping (m) ? match_port
+       : m->external_port;
+      *mapping_fib_index = sm->outside_fib_index;
     }
 
 end:
@@ -2881,219 +3082,16 @@ end:
   if (PREDICT_FALSE (is_identity_nat != 0))
     *is_identity_nat = is_identity_static_mapping (m);
 
-  return 0;
-}
-
-static_always_inline u16
-snat_random_port (u16 min, u16 max)
-{
-  snat_main_t *sm = &snat_main;
-  return min + random_u32 (&sm->random_seed) /
-    (random_u32_max () / (max - min + 1) + 1);
-}
+  if (out != 0)
+    *out = m;
 
-int
-snat_alloc_outside_address_and_port (snat_address_t * addresses,
-                                    u32 fib_index,
-                                    u32 thread_index,
-                                    snat_session_key_t * k,
-                                    u16 port_per_thread,
-                                    u32 snat_thread_index)
-{
-  snat_main_t *sm = &snat_main;
-
-  return sm->alloc_addr_and_port (addresses, fib_index, thread_index, k,
-                                 port_per_thread, snat_thread_index);
-}
-
-static int
-nat_alloc_addr_and_port_default (snat_address_t * addresses,
-                                u32 fib_index,
-                                u32 thread_index,
-                                snat_session_key_t * k,
-                                u16 port_per_thread, u32 snat_thread_index)
-{
-  int i;
-  snat_address_t *a, *ga = 0;
-  u32 portnum;
-
-  for (i = 0; i < vec_len (addresses); i++)
-    {
-      a = addresses + i;
-      switch (k->protocol)
-       {
-#define _(N, j, n, s) \
-        case SNAT_PROTOCOL_##N: \
-          if (a->busy_##n##_ports_per_thread[thread_index] < port_per_thread) \
-            { \
-              if (a->fib_index == fib_index) \
-                { \
-                  while (1) \
-                    { \
-                      portnum = (port_per_thread * \
-                        snat_thread_index) + \
-                        snat_random_port(1, port_per_thread) + 1024; \
-                      if (a->busy_##n##_port_refcounts[portnum]) \
-                        continue; \
-                     --a->busy_##n##_port_refcounts[portnum]; \
-                      a->busy_##n##_ports_per_thread[thread_index]++; \
-                      a->busy_##n##_ports++; \
-                      k->addr = a->addr; \
-                      k->port = clib_host_to_net_u16(portnum); \
-                      return 0; \
-                    } \
-                } \
-              else if (a->fib_index == ~0) \
-                { \
-                  ga = a; \
-                } \
-            } \
-          break;
-         foreach_snat_protocol
-#undef _
-       default:
-         nat_elog_info ("unknown protocol");
-         return 1;
-       }
-
-    }
-
-  if (ga)
-    {
-      a = ga;
-      switch (k->protocol)
-       {
-#define _(N, j, n, s) \
-        case SNAT_PROTOCOL_##N: \
-          while (1) \
-            { \
-              portnum = (port_per_thread * \
-                snat_thread_index) + \
-                snat_random_port(1, port_per_thread) + 1024; \
-             if (a->busy_##n##_port_refcounts[portnum]) \
-                continue; \
-             ++a->busy_##n##_port_refcounts[portnum]; \
-              a->busy_##n##_ports_per_thread[thread_index]++; \
-              a->busy_##n##_ports++; \
-              k->addr = a->addr; \
-              k->port = clib_host_to_net_u16(portnum); \
-              return 0; \
-            }
-         break;
-         foreach_snat_protocol
-#undef _
-       default:
-         nat_elog_info ("unknown protocol");
-         return 1;
-       }
-    }
-
-  /* Totally out of translations to use... */
-  snat_ipfix_logging_addresses_exhausted (thread_index, 0);
-  return 1;
-}
-
-static int
-nat_alloc_addr_and_port_mape (snat_address_t * addresses,
-                             u32 fib_index,
-                             u32 thread_index,
-                             snat_session_key_t * k,
-                             u16 port_per_thread, u32 snat_thread_index)
-{
-  snat_main_t *sm = &snat_main;
-  snat_address_t *a = addresses;
-  u16 m, ports, portnum, A, j;
-  m = 16 - (sm->psid_offset + sm->psid_length);
-  ports = (1 << (16 - sm->psid_length)) - (1 << m);
-
-  if (!vec_len (addresses))
-    goto exhausted;
-
-  switch (k->protocol)
-    {
-#define _(N, i, n, s) \
-    case SNAT_PROTOCOL_##N: \
-      if (a->busy_##n##_ports < ports) \
-        { \
-          while (1) \
-            { \
-              A = snat_random_port(1, pow2_mask(sm->psid_offset)); \
-              j = snat_random_port(0, pow2_mask(m)); \
-              portnum = A | (sm->psid << sm->psid_offset) | (j << (16 - m)); \
-             if (a->busy_##n##_port_refcounts[portnum]) \
-                continue; \
-             ++a->busy_##n##_port_refcounts[portnum]; \
-              a->busy_##n##_ports++; \
-              k->addr = a->addr; \
-              k->port = clib_host_to_net_u16 (portnum); \
-              return 0; \
-            } \
-        } \
-      break;
-      foreach_snat_protocol
-#undef _
-    default:
-      nat_elog_info ("unknown protocol");
-      return 1;
-    }
-
-exhausted:
-  /* Totally out of translations to use... */
-  snat_ipfix_logging_addresses_exhausted (thread_index, 0);
-  return 1;
-}
-
-static int
-nat_alloc_addr_and_port_range (snat_address_t * addresses,
-                              u32 fib_index,
-                              u32 thread_index,
-                              snat_session_key_t * k,
-                              u16 port_per_thread, u32 snat_thread_index)
-{
-  snat_main_t *sm = &snat_main;
-  snat_address_t *a = addresses;
-  u16 portnum, ports;
-
-  ports = sm->end_port - sm->start_port + 1;
-
-  if (!vec_len (addresses))
-    goto exhausted;
-
-  switch (k->protocol)
-    {
-#define _(N, i, n, s) \
-    case SNAT_PROTOCOL_##N: \
-      if (a->busy_##n##_ports < ports) \
-        { \
-          while (1) \
-            { \
-              portnum = snat_random_port(sm->start_port, sm->end_port); \
-             if (a->busy_##n##_port_refcounts[portnum]) \
-                continue; \
-             ++a->busy_##n##_port_refcounts[portnum]; \
-              a->busy_##n##_ports++; \
-              k->addr = a->addr; \
-              k->port = clib_host_to_net_u16 (portnum); \
-              return 0; \
-            } \
-        } \
-      break;
-      foreach_snat_protocol
-#undef _
-    default:
-      nat_elog_info ("unknown protocol");
-      return 1;
-    }
-
-exhausted:
-  /* Totally out of translations to use... */
-  snat_ipfix_logging_addresses_exhausted (thread_index, 0);
-  return 1;
+  return 0;
 }
 
 void
 nat44_add_del_address_dpo (ip4_address_t addr, u8 is_add)
 {
+  snat_main_t *sm = &snat_main;
   dpo_id_t dpo_v4 = DPO_INVALID;
   fib_prefix_t pfx = {
     .fp_proto = FIB_PROTOCOL_IP4,
@@ -3104,190 +3102,18 @@ nat44_add_del_address_dpo (ip4_address_t addr, u8 is_add)
   if (is_add)
     {
       nat_dpo_create (DPO_PROTO_IP4, 0, &dpo_v4);
-      fib_table_entry_special_dpo_add (0, &pfx, nat_fib_src_hi,
+      fib_table_entry_special_dpo_add (0, &pfx, sm->fib_src_hi,
                                       FIB_ENTRY_FLAG_EXCLUSIVE, &dpo_v4);
       dpo_reset (&dpo_v4);
     }
   else
     {
-      fib_table_entry_special_remove (0, &pfx, nat_fib_src_hi);
+      fib_table_entry_special_remove (0, &pfx, sm->fib_src_hi);
     }
 }
 
-u8 *
-format_session_kvp (u8 * s, va_list * args)
-{
-  clib_bihash_kv_8_8_t *v = va_arg (*args, clib_bihash_kv_8_8_t *);
-  snat_session_key_t k;
-
-  k.as_u64 = v->key;
-
-  s = format (s, "%U session-index %llu", format_snat_key, &k, v->value);
-
-  return s;
-}
-
-u8 *
-format_static_mapping_kvp (u8 * s, va_list * args)
-{
-  clib_bihash_kv_8_8_t *v = va_arg (*args, clib_bihash_kv_8_8_t *);
-  snat_session_key_t k;
-
-  k.as_u64 = v->key;
-
-  s = format (s, "%U static-mapping-index %llu",
-             format_static_mapping_key, &k, v->value);
-
-  return s;
-}
-
-u8 *
-format_user_kvp (u8 * s, va_list * args)
-{
-  clib_bihash_kv_8_8_t *v = va_arg (*args, clib_bihash_kv_8_8_t *);
-  snat_user_key_t k;
-
-  k.as_u64 = v->key;
-
-  s = format (s, "%U fib %d user-index %llu", format_ip4_address, &k.addr,
-             k.fib_index, v->value);
-
-  return s;
-}
-
-u8 *
-format_ed_session_kvp (u8 * s, va_list * args)
-{
-  clib_bihash_kv_16_8_t *v = va_arg (*args, clib_bihash_kv_16_8_t *);
-  nat_ed_ses_key_t k;
-
-  k.as_u64[0] = v->key[0];
-  k.as_u64[1] = v->key[1];
-
-  s =
-    format (s, "local %U:%d remote %U:%d proto %U fib %d session-index %llu",
-           format_ip4_address, &k.l_addr, clib_net_to_host_u16 (k.l_port),
-           format_ip4_address, &k.r_addr, clib_net_to_host_u16 (k.r_port),
-           format_ip_protocol, k.proto, k.fib_index, v->value);
-
-  return s;
-}
-
 static u32
-snat_get_worker_in2out_cb (ip4_header_t * ip0, u32 rx_fib_index0,
-                          u8 is_output)
-{
-  snat_main_t *sm = &snat_main;
-  u32 next_worker_index = 0;
-  u32 hash;
-
-  next_worker_index = sm->first_worker_index;
-  hash = ip0->src_address.as_u32 + (ip0->src_address.as_u32 >> 8) +
-    (ip0->src_address.as_u32 >> 16) + (ip0->src_address.as_u32 >> 24);
-
-  if (PREDICT_TRUE (is_pow2 (_vec_len (sm->workers))))
-    next_worker_index += sm->workers[hash & (_vec_len (sm->workers) - 1)];
-  else
-    next_worker_index += sm->workers[hash % _vec_len (sm->workers)];
-
-  return next_worker_index;
-}
-
-static u32
-snat_get_worker_out2in_cb (vlib_buffer_t * b, ip4_header_t * ip0,
-                          u32 rx_fib_index0, u8 is_output)
-{
-  snat_main_t *sm = &snat_main;
-  udp_header_t *udp;
-  u16 port;
-  snat_session_key_t m_key;
-  clib_bihash_kv_8_8_t kv, value;
-  snat_static_mapping_t *m;
-  u32 proto;
-  u32 next_worker_index = 0;
-
-  /* first try static mappings without port */
-  if (PREDICT_FALSE (pool_elts (sm->static_mappings)))
-    {
-      m_key.addr = ip0->dst_address;
-      m_key.port = 0;
-      m_key.protocol = 0;
-      m_key.fib_index = rx_fib_index0;
-      kv.key = m_key.as_u64;
-      if (!clib_bihash_search_8_8
-         (&sm->static_mapping_by_external, &kv, &value))
-       {
-         m = pool_elt_at_index (sm->static_mappings, value.value);
-         return m->workers[0];
-       }
-    }
-
-  proto = ip_proto_to_snat_proto (ip0->protocol);
-  udp = ip4_next_header (ip0);
-  port = udp->dst_port;
-
-  /* unknown protocol */
-  if (PREDICT_FALSE (proto == ~0))
-    {
-      /* use current thread */
-      return vlib_get_thread_index ();
-    }
-
-  if (PREDICT_FALSE (ip0->protocol == IP_PROTOCOL_ICMP))
-    {
-      icmp46_header_t *icmp = (icmp46_header_t *) udp;
-      icmp_echo_header_t *echo = (icmp_echo_header_t *) (icmp + 1);
-      if (!icmp_type_is_error_message
-         (vnet_buffer (b)->ip.reass.icmp_type_or_tcp_flags))
-       port = vnet_buffer (b)->ip.reass.l4_src_port;
-      else
-       {
-         /* if error message, then it's not fragmented and we can access it */
-         ip4_header_t *inner_ip = (ip4_header_t *) (echo + 1);
-         proto = ip_proto_to_snat_proto (inner_ip->protocol);
-         void *l4_header = ip4_next_header (inner_ip);
-         switch (proto)
-           {
-           case SNAT_PROTOCOL_ICMP:
-             icmp = (icmp46_header_t *) l4_header;
-             echo = (icmp_echo_header_t *) (icmp + 1);
-             port = echo->identifier;
-             break;
-           case SNAT_PROTOCOL_UDP:
-           case SNAT_PROTOCOL_TCP:
-             port = ((tcp_udp_header_t *) l4_header)->src_port;
-             break;
-           default:
-             return vlib_get_thread_index ();
-           }
-       }
-    }
-
-  /* try static mappings with port */
-  if (PREDICT_FALSE (pool_elts (sm->static_mappings)))
-    {
-      m_key.addr = ip0->dst_address;
-      m_key.port = clib_net_to_host_u16 (port);
-      m_key.protocol = proto;
-      m_key.fib_index = rx_fib_index0;
-      kv.key = m_key.as_u64;
-      if (!clib_bihash_search_8_8
-         (&sm->static_mapping_by_external, &kv, &value))
-       {
-         m = pool_elt_at_index (sm->static_mappings, value.value);
-         return m->workers[0];
-       }
-    }
-
-  /* worker by outside port */
-  next_worker_index = sm->first_worker_index;
-  next_worker_index +=
-    sm->workers[(clib_net_to_host_u16 (port) - 1024) / sm->port_per_thread];
-  return next_worker_index;
-}
-
-static u32
-nat44_ed_get_worker_in2out_cb (ip4_header_t * ip, u32 rx_fib_index,
+nat44_ed_get_worker_in2out_cb (ip4_header_t *ip, u32 rx_fib_index,
                               u8 is_output)
 {
   snat_main_t *sm = &snat_main;
@@ -3340,27 +3166,26 @@ nat44_ed_get_worker_in2out_cb (ip4_header_t * ip, u32 rx_fib_index,
          break;
        }
 
-      make_ed_kv (&kv16, &ip->src_address, &ip->dst_address,
-                 ip->protocol, fib_index, udp->src_port, udp->dst_port);
-
-      /* *INDENT-OFF* */
-      vec_foreach (tsm, sm->per_thread_data)
-        {
-          if (PREDICT_TRUE (!clib_bihash_search_16_8 (&tsm->out2in_ed,
-                                                      &kv16, &value16)))
-            {
-              next_worker_index += tsm->thread_index;
-
-              nat_elog_debug_handoff (
-                "HANDOFF IN2OUT-OUTPUT-FEATURE (session)",
-                next_worker_index, fib_index,
-               clib_net_to_host_u32 (ip->src_address.as_u32),
-               clib_net_to_host_u32 (ip->dst_address.as_u32));
+      init_ed_k (&kv16, ip->src_address, udp->src_port, ip->dst_address,
+                udp->dst_port, fib_index, ip->protocol);
 
-              return next_worker_index;
-            }
-        }
-      /* *INDENT-ON* */
+      if (PREDICT_TRUE (
+           !clib_bihash_search_16_8 (&sm->flow_hash, &kv16, &value16)))
+       {
+         tsm =
+           vec_elt_at_index (sm->per_thread_data,
+                             ed_value_get_thread_index (&value16));
+         next_worker_index += tsm->thread_index;
+
+         nat_elog_debug_handoff ("HANDOFF IN2OUT-OUTPUT-FEATURE (session)",
+                                 next_worker_index, fib_index,
+                                 clib_net_to_host_u32 (ip->
+                                                       src_address.as_u32),
+                                 clib_net_to_host_u32 (ip->
+                                                       dst_address.as_u32));
+
+         return next_worker_index;
+       }
     }
 
   hash = ip->src_address.as_u32 + (ip->src_address.as_u32 >> 8) +
@@ -3404,65 +3229,66 @@ nat44_ed_get_worker_out2in_cb (vlib_buffer_t * b, ip4_header_t * ip,
   snat_static_mapping_t *m;
   u32 hash;
 
-  proto = ip_proto_to_snat_proto (ip->protocol);
+  proto = ip_proto_to_nat_proto (ip->protocol);
 
-  if (PREDICT_TRUE (proto == SNAT_PROTOCOL_UDP || proto == SNAT_PROTOCOL_TCP))
+  if (PREDICT_TRUE (proto == NAT_PROTOCOL_UDP || proto == NAT_PROTOCOL_TCP))
     {
       udp = ip4_next_header (ip);
 
-      make_ed_kv (&kv16, &ip->dst_address, &ip->src_address,
-                 ip->protocol, rx_fib_index, udp->dst_port, udp->src_port);
+      init_ed_k (&kv16, ip->dst_address, udp->dst_port, ip->src_address,
+                udp->src_port, rx_fib_index, ip->protocol);
 
-      /* *INDENT-OFF* */
-      vec_foreach (tsm, sm->per_thread_data)
-        {
-          if (PREDICT_TRUE (!clib_bihash_search_16_8 (&tsm->out2in_ed,
-                                                      &kv16, &value16)))
-            {
-              next_worker_index = sm->first_worker_index + tsm->thread_index;
-              nat_elog_debug_handoff ("HANDOFF OUT2IN (session)",
-                          next_worker_index, rx_fib_index,
-                         clib_net_to_host_u32 (ip->src_address.as_u32),
-                         clib_net_to_host_u32 (ip->dst_address.as_u32));
-              return next_worker_index;
-            }
-          }
-        /* *INDENT-ON* */
+      if (PREDICT_TRUE (
+           !clib_bihash_search_16_8 (&sm->flow_hash, &kv16, &value16)))
+       {
+         tsm =
+           vec_elt_at_index (sm->per_thread_data,
+                             ed_value_get_thread_index (&value16));
+         vnet_buffer2 (b)->nat.cached_session_index =
+           ed_value_get_session_index (&value16);
+         next_worker_index = sm->first_worker_index + tsm->thread_index;
+         nat_elog_debug_handoff ("HANDOFF OUT2IN (session)",
+                                 next_worker_index, rx_fib_index,
+                                 clib_net_to_host_u32 (ip->
+                                                       src_address.as_u32),
+                                 clib_net_to_host_u32 (ip->
+                                                       dst_address.as_u32));
+         return next_worker_index;
+       }
     }
-  else if (proto == SNAT_PROTOCOL_ICMP)
+  else if (proto == NAT_PROTOCOL_ICMP)
     {
-      nat_ed_ses_key_t key;
-
-      if (!get_icmp_o2i_ed_key (b, ip, &key))
+      ip4_address_t lookup_saddr, lookup_daddr;
+      u16 lookup_sport, lookup_dport;
+      u8 lookup_protocol;
+      if (!nat_get_icmp_session_lookup_values (
+           b, ip, &lookup_saddr, &lookup_sport, &lookup_daddr, &lookup_dport,
+           &lookup_protocol))
        {
-
-         key.fib_index = rx_fib_index;
-         kv16.key[0] = key.as_u64[0];
-         kv16.key[1] = key.as_u64[1];
-
-          /* *INDENT-OFF* */
-          vec_foreach (tsm, sm->per_thread_data)
-            {
-              if (PREDICT_TRUE (!clib_bihash_search_16_8 (&tsm->out2in_ed,
-                                                          &kv16, &value16)))
-                {
-                  next_worker_index = sm->first_worker_index +
-                                      tsm->thread_index;
-                  nat_elog_debug_handoff ("HANDOFF OUT2IN (session)",
-                              next_worker_index, rx_fib_index,
-                             clib_net_to_host_u32 (ip->src_address.as_u32),
-                             clib_net_to_host_u32 (ip->dst_address.as_u32));
-                  return next_worker_index;
-                }
-            }
-          /* *INDENT-ON* */
+         init_ed_k (&kv16, lookup_saddr, lookup_sport, lookup_daddr,
+                    lookup_dport, rx_fib_index, lookup_protocol);
+         if (PREDICT_TRUE (
+               !clib_bihash_search_16_8 (&sm->flow_hash, &kv16, &value16)))
+           {
+             tsm =
+               vec_elt_at_index (sm->per_thread_data,
+                                 ed_value_get_thread_index (&value16));
+             next_worker_index = sm->first_worker_index + tsm->thread_index;
+             nat_elog_debug_handoff ("HANDOFF OUT2IN (session)",
+                                     next_worker_index, rx_fib_index,
+                                     clib_net_to_host_u32 (ip->
+                                                           src_address.as_u32),
+                                     clib_net_to_host_u32 (ip->
+                                                           dst_address.as_u32));
+             return next_worker_index;
+           }
        }
     }
 
   /* first try static mappings without port */
   if (PREDICT_FALSE (pool_elts (sm->static_mappings)))
     {
-      make_sm_kv (&kv, &ip->dst_address, 0, 0, 0);
+      init_nat_k (&kv, ip->dst_address, 0, 0, 0);
       if (!clib_bihash_search_8_8
          (&sm->static_mapping_by_external, &kv, &value))
        {
@@ -3473,7 +3299,7 @@ nat44_ed_get_worker_out2in_cb (vlib_buffer_t * b, ip4_header_t * ip,
     }
 
   /* unknown protocol */
-  if (PREDICT_FALSE (proto == ~0))
+  if (PREDICT_FALSE (proto == NAT_PROTOCOL_OTHER))
     {
       /* use current thread */
       next_worker_index = vlib_get_thread_index ();
@@ -3494,17 +3320,17 @@ nat44_ed_get_worker_out2in_cb (vlib_buffer_t * b, ip4_header_t * ip,
        {
          /* if error message, then it's not fragmented and we can access it */
          ip4_header_t *inner_ip = (ip4_header_t *) (echo + 1);
-         proto = ip_proto_to_snat_proto (inner_ip->protocol);
+         proto = ip_proto_to_nat_proto (inner_ip->protocol);
          void *l4_header = ip4_next_header (inner_ip);
          switch (proto)
            {
-           case SNAT_PROTOCOL_ICMP:
+           case NAT_PROTOCOL_ICMP:
              icmp = (icmp46_header_t *) l4_header;
              echo = (icmp_echo_header_t *) (icmp + 1);
              port = echo->identifier;
              break;
-           case SNAT_PROTOCOL_UDP:
-           case SNAT_PROTOCOL_TCP:
+           case NAT_PROTOCOL_UDP:
+           case NAT_PROTOCOL_TCP:
              port = ((tcp_udp_header_t *) l4_header)->src_port;
              break;
            default:
@@ -3517,8 +3343,7 @@ nat44_ed_get_worker_out2in_cb (vlib_buffer_t * b, ip4_header_t * ip,
   /* try static mappings with port */
   if (PREDICT_FALSE (pool_elts (sm->static_mappings)))
     {
-      make_sm_kv (&kv, &ip->dst_address, proto, 0,
-                 clib_net_to_host_u16 (port));
+      init_nat_k (&kv, ip->dst_address, port, 0, proto);
       if (!clib_bihash_search_8_8
          (&sm->static_mapping_by_external, &kv, &value))
        {
@@ -3553,595 +3378,223 @@ done:
   return next_worker_index;
 }
 
-void
-nat_ha_sadd_cb (ip4_address_t * in_addr, u16 in_port,
-               ip4_address_t * out_addr, u16 out_port,
-               ip4_address_t * eh_addr, u16 eh_port,
-               ip4_address_t * ehn_addr, u16 ehn_port, u8 proto,
-               u32 fib_index, u16 flags, u32 thread_index)
+u32
+nat_calc_bihash_buckets (u32 n_elts)
 {
-  snat_main_t *sm = &snat_main;
-  snat_session_key_t key;
-  snat_user_t *u;
-  snat_session_t *s;
-  clib_bihash_kv_8_8_t kv;
-  f64 now = vlib_time_now (sm->vlib_main);
-  nat_outside_fib_t *outside_fib;
-  fib_node_index_t fei = FIB_NODE_INDEX_INVALID;
-  snat_main_per_thread_data_t *tsm;
-  fib_prefix_t pfx = {
-    .fp_proto = FIB_PROTOCOL_IP4,
-    .fp_len = 32,
-    .fp_addr = {
-               .ip4.as_u32 = eh_addr->as_u32,
-               },
-  };
-
-  tsm = vec_elt_at_index (sm->per_thread_data, thread_index);
-
-  key.addr.as_u32 = out_addr->as_u32;
-  key.port = out_port;
-  key.protocol = proto;
-
-  if (!(flags & SNAT_SESSION_FLAG_STATIC_MAPPING))
+  n_elts = n_elts / 2.5;
+  u64 lower_pow2 = 1;
+  while (lower_pow2 * 2 < n_elts)
     {
-      if (nat_set_outside_address_and_port
-         (sm->addresses, thread_index, &key))
-       return;
+      lower_pow2 = 2 * lower_pow2;
     }
+  u64 upper_pow2 = 2 * lower_pow2;
+  if ((upper_pow2 - n_elts) < (n_elts - lower_pow2))
+    {
+      if (upper_pow2 <= UINT32_MAX)
+       {
+         return upper_pow2;
+       }
+    }
+  return lower_pow2;
+}
 
-  u = nat_user_get_or_create (sm, in_addr, fib_index, thread_index);
-  if (!u)
-    return;
-
-  s = nat_session_alloc_or_recycle (sm, u, thread_index, now);
-  if (!s)
-    return;
+u32
+nat44_get_max_session_limit ()
+{
+  snat_main_t *sm = &snat_main;
+  u32 max_limit = 0, len = 0;
 
-  s->last_heard = now;
-  s->flags = flags;
-  s->ext_host_addr.as_u32 = eh_addr->as_u32;
-  s->ext_host_port = eh_port;
-  user_session_increment (sm, u, snat_is_session_static (s));
-  switch (vec_len (sm->outside_fibs))
+  for (; len < vec_len (sm->max_translations_per_fib); len++)
     {
-    case 0:
-      key.fib_index = sm->outside_fib_index;
-      break;
-    case 1:
-      key.fib_index = sm->outside_fibs[0].fib_index;
-      break;
-    default:
-      /* *INDENT-OFF* */
-      vec_foreach (outside_fib, sm->outside_fibs)
-        {
-          fei = fib_table_lookup (outside_fib->fib_index, &pfx);
-          if (FIB_NODE_INDEX_INVALID != fei)
-            {
-              if (fib_entry_get_resolving_interface (fei) != ~0)
-                {
-                  key.fib_index = outside_fib->fib_index;
-                  break;
-                }
-            }
-        }
-      /* *INDENT-ON* */
-      break;
+      if (max_limit < sm->max_translations_per_fib[len])
+       max_limit = sm->max_translations_per_fib[len];
     }
-  s->out2in = key;
-  kv.key = key.as_u64;
-  kv.value = s - tsm->sessions;
-  if (clib_bihash_add_del_8_8 (&tsm->out2in, &kv, 1))
-    nat_elog_warn ("out2in key add failed");
-
-  key.addr.as_u32 = in_addr->as_u32;
-  key.port = in_port;
-  key.fib_index = fib_index;
-  s->in2out = key;
-  kv.key = key.as_u64;
-  if (clib_bihash_add_del_8_8 (&tsm->in2out, &kv, 1))
-    nat_elog_warn ("in2out key add failed");
+  return max_limit;
 }
 
-void
-nat_ha_sdel_cb (ip4_address_t * out_addr, u16 out_port,
-               ip4_address_t * eh_addr, u16 eh_port, u8 proto, u32 fib_index,
-               u32 ti)
+int
+nat44_set_session_limit (u32 session_limit, u32 vrf_id)
 {
   snat_main_t *sm = &snat_main;
-  snat_session_key_t key;
-  clib_bihash_kv_8_8_t kv, value;
-  u32 thread_index;
-  snat_session_t *s;
-  snat_main_per_thread_data_t *tsm;
+  u32 fib_index = fib_table_find (FIB_PROTOCOL_IP4, vrf_id);
+  u32 len = vec_len (sm->max_translations_per_fib);
 
-  if (sm->num_workers > 1)
-    thread_index =
-      sm->first_worker_index +
-      (sm->workers[(clib_net_to_host_u16 (out_port) -
-                   1024) / sm->port_per_thread]);
-  else
-    thread_index = sm->num_workers;
-  tsm = vec_elt_at_index (sm->per_thread_data, thread_index);
-
-  key.addr.as_u32 = out_addr->as_u32;
-  key.port = out_port;
-  key.protocol = proto;
-  key.fib_index = fib_index;
-  kv.key = key.as_u64;
-  if (clib_bihash_search_8_8 (&tsm->out2in, &kv, &value))
-    return;
+  if (len <= fib_index)
+    {
+      vec_validate (sm->max_translations_per_fib, fib_index + 1);
+
+      for (; len < vec_len (sm->max_translations_per_fib); len++)
+       sm->max_translations_per_fib[len] = sm->max_translations_per_thread;
+    }
 
-  s = pool_elt_at_index (tsm->sessions, value.value);
-  nat_free_session_data (sm, s, thread_index, 1);
-  nat44_delete_session (sm, s, thread_index);
+  sm->max_translations_per_fib[fib_index] = session_limit;
+  return 0;
 }
 
-void
-nat_ha_sref_cb (ip4_address_t * out_addr, u16 out_port,
-               ip4_address_t * eh_addr, u16 eh_port, u8 proto, u32 fib_index,
-               u32 total_pkts, u64 total_bytes, u32 thread_index)
+int
+nat44_update_session_limit (u32 session_limit, u32 vrf_id)
 {
   snat_main_t *sm = &snat_main;
-  snat_session_key_t key;
-  clib_bihash_kv_8_8_t kv, value;
-  snat_session_t *s;
-  snat_main_per_thread_data_t *tsm;
 
-  tsm = vec_elt_at_index (sm->per_thread_data, thread_index);
+  if (nat44_set_session_limit (session_limit, vrf_id))
+    return 1;
+  sm->max_translations_per_thread = nat44_get_max_session_limit ();
 
-  key.addr.as_u32 = out_addr->as_u32;
-  key.port = out_port;
-  key.protocol = proto;
-  key.fib_index = fib_index;
-  kv.key = key.as_u64;
-  if (clib_bihash_search_8_8 (&tsm->out2in, &kv, &value))
-    return;
+  sm->translation_buckets =
+    nat_calc_bihash_buckets (sm->max_translations_per_thread);
 
-  s = pool_elt_at_index (tsm->sessions, value.value);
-  s->total_pkts = total_pkts;
-  s->total_bytes = total_bytes;
+  nat44_sessions_clear ();
+  return 0;
 }
 
-void
-nat_ha_sadd_ed_cb (ip4_address_t * in_addr, u16 in_port,
-                  ip4_address_t * out_addr, u16 out_port,
-                  ip4_address_t * eh_addr, u16 eh_port,
-                  ip4_address_t * ehn_addr, u16 ehn_port, u8 proto,
-                  u32 fib_index, u16 flags, u32 thread_index)
+static void
+nat44_ed_worker_db_init (snat_main_per_thread_data_t *tsm, u32 translations,
+                        u32 translation_buckets, u32 user_buckets)
 {
-  snat_main_t *sm = &snat_main;
-  snat_session_key_t key;
-  snat_session_t *s;
-  clib_bihash_kv_16_8_t kv;
-  f64 now = vlib_time_now (sm->vlib_main);
-  nat_outside_fib_t *outside_fib;
-  fib_node_index_t fei = FIB_NODE_INDEX_INVALID;
-  snat_main_per_thread_data_t *tsm;
-  fib_prefix_t pfx = {
-    .fp_proto = FIB_PROTOCOL_IP4,
-    .fp_len = 32,
-    .fp_addr = {
-               .ip4.as_u32 = eh_addr->as_u32,
-               },
-  };
+  dlist_elt_t *head;
 
-  tsm = vec_elt_at_index (sm->per_thread_data, thread_index);
+  pool_alloc (tsm->sessions, translations);
+  pool_alloc (tsm->lru_pool, translations);
 
-  key.addr.as_u32 = out_addr->as_u32;
-  key.port = out_port;
-  key.protocol = proto;
+  pool_get (tsm->lru_pool, head);
+  tsm->tcp_trans_lru_head_index = head - tsm->lru_pool;
+  clib_dlist_init (tsm->lru_pool, tsm->tcp_trans_lru_head_index);
 
-  if (!(flags & SNAT_SESSION_FLAG_STATIC_MAPPING))
-    {
-      if (nat_set_outside_address_and_port
-         (sm->addresses, thread_index, &key))
-       return;
-    }
+  pool_get (tsm->lru_pool, head);
+  tsm->tcp_estab_lru_head_index = head - tsm->lru_pool;
+  clib_dlist_init (tsm->lru_pool, tsm->tcp_estab_lru_head_index);
 
-  key.addr.as_u32 = ehn_addr->as_u32;
-  key.port = ehn_port;
-  if (flags & SNAT_SESSION_FLAG_TWICE_NAT)
-    {
-      if (nat_set_outside_address_and_port
-         (sm->twice_nat_addresses, thread_index, &key))
-       return;
-    }
+  pool_get (tsm->lru_pool, head);
+  tsm->udp_lru_head_index = head - tsm->lru_pool;
+  clib_dlist_init (tsm->lru_pool, tsm->udp_lru_head_index);
 
-  s = nat_ed_session_alloc (sm, thread_index, now);
-  if (!s)
-    return;
+  pool_get (tsm->lru_pool, head);
+  tsm->icmp_lru_head_index = head - tsm->lru_pool;
+  clib_dlist_init (tsm->lru_pool, tsm->icmp_lru_head_index);
 
-  s->last_heard = now;
-  s->flags = flags;
-  s->ext_host_nat_addr.as_u32 = s->ext_host_addr.as_u32 = eh_addr->as_u32;
-  s->ext_host_nat_port = s->ext_host_port = eh_port;
-  if (is_twice_nat_session (s))
-    {
-      s->ext_host_nat_addr.as_u32 = ehn_addr->as_u32;
-      s->ext_host_nat_port = ehn_port;
-    }
-  switch (vec_len (sm->outside_fibs))
-    {
-    case 0:
-      key.fib_index = sm->outside_fib_index;
-      break;
-    case 1:
-      key.fib_index = sm->outside_fibs[0].fib_index;
-      break;
-    default:
-      /* *INDENT-OFF* */
-      vec_foreach (outside_fib, sm->outside_fibs)
-        {
-          fei = fib_table_lookup (outside_fib->fib_index, &pfx);
-          if (FIB_NODE_INDEX_INVALID != fei)
-            {
-              if (fib_entry_get_resolving_interface (fei) != ~0)
-                {
-                  key.fib_index = outside_fib->fib_index;
-                  break;
-                }
-            }
-        }
-      /* *INDENT-ON* */
-      break;
-    }
-  key.addr.as_u32 = out_addr->as_u32;
-  key.port = out_port;
-  s->out2in = key;
-  kv.value = s - tsm->sessions;
-
-  key.addr.as_u32 = in_addr->as_u32;
-  key.port = in_port;
-  key.fib_index = fib_index;
-  s->in2out = key;
-
-  make_ed_kv (&kv, in_addr, &s->ext_host_nat_addr,
-             snat_proto_to_ip_proto (proto), fib_index, in_port,
-             s->ext_host_nat_port);
-  if (clib_bihash_add_del_16_8 (&tsm->in2out_ed, &kv, 1))
-    nat_elog_warn ("in2out key add failed");
-
-  make_ed_kv (&kv, out_addr, eh_addr, snat_proto_to_ip_proto (proto),
-             s->out2in.fib_index, out_port, eh_port);
-  if (clib_bihash_add_del_16_8 (&tsm->out2in_ed, &kv, 1))
-    nat_elog_warn ("out2in key add failed");
+  pool_get (tsm->lru_pool, head);
+  tsm->unk_proto_lru_head_index = head - tsm->lru_pool;
+  clib_dlist_init (tsm->lru_pool, tsm->unk_proto_lru_head_index);
+
+  // TODO: ED nat is not using these
+  // before removal large refactor required
+  pool_alloc (tsm->list_pool, translations);
+  clib_bihash_init_8_8 (&tsm->user_hash, "users", user_buckets, 0);
+  clib_bihash_set_kvp_format_fn_8_8 (&tsm->user_hash, format_user_kvp);
 }
 
-void
-nat_ha_sdel_ed_cb (ip4_address_t * out_addr, u16 out_port,
-                  ip4_address_t * eh_addr, u16 eh_port, u8 proto,
-                  u32 fib_index, u32 ti)
+static void
+reinit_ed_flow_hash ()
+{
+  snat_main_t *sm = &snat_main;
+  // we expect 2 flows per session, so multiply translation_buckets by 2
+  clib_bihash_init_16_8 (
+    &sm->flow_hash, "ed-flow-hash",
+    clib_max (1, sm->num_workers) * 2 * sm->translation_buckets, 0);
+  clib_bihash_set_kvp_format_fn_16_8 (&sm->flow_hash, format_ed_session_kvp);
+}
+
+static void
+nat44_ed_db_init (u32 translations, u32 translation_buckets, u32 user_buckets)
 {
   snat_main_t *sm = &snat_main;
-  nat_ed_ses_key_t key;
-  clib_bihash_kv_16_8_t kv, value;
-  u32 thread_index;
-  snat_session_t *s;
   snat_main_per_thread_data_t *tsm;
+  u32 static_mapping_buckets = 1024;
+  u32 static_mapping_memory_size = 64 << 20;
 
-  if (sm->num_workers > 1)
-    thread_index =
-      sm->first_worker_index +
-      (sm->workers[(clib_net_to_host_u16 (out_port) -
-                   1024) / sm->port_per_thread]);
-  else
-    thread_index = sm->num_workers;
-  tsm = vec_elt_at_index (sm->per_thread_data, thread_index);
-
-  key.l_addr.as_u32 = out_addr->as_u32;
-  key.l_port = out_port;
-  key.r_addr.as_u32 = eh_addr->as_u32;
-  key.r_port = eh_port;
-  key.proto = proto;
-  key.fib_index = fib_index;
-  kv.key[0] = key.as_u64[0];
-  kv.key[1] = key.as_u64[1];
-  if (clib_bihash_search_16_8 (&tsm->out2in_ed, &kv, &value))
-    return;
+  reinit_ed_flow_hash ();
+
+  clib_bihash_init_8_8 (&sm->static_mapping_by_local,
+                       "static_mapping_by_local", static_mapping_buckets,
+                       static_mapping_memory_size);
+  clib_bihash_set_kvp_format_fn_8_8 (&sm->static_mapping_by_local,
+                                    format_static_mapping_kvp);
+
+  clib_bihash_init_8_8 (&sm->static_mapping_by_external,
+                       "static_mapping_by_external", static_mapping_buckets,
+                       static_mapping_memory_size);
+  clib_bihash_set_kvp_format_fn_8_8 (&sm->static_mapping_by_external,
+                                    format_static_mapping_kvp);
 
-  s = pool_elt_at_index (tsm->sessions, value.value);
-  nat_free_session_data (sm, s, thread_index, 1);
-  nat44_delete_session (sm, s, thread_index);
+  if (sm->pat)
+    {
+      vec_foreach (tsm, sm->per_thread_data)
+       {
+         nat44_ed_worker_db_init (tsm, sm->max_translations_per_thread,
+                                  sm->translation_buckets, sm->user_buckets);
+       }
+    }
 }
 
-void
-nat_ha_sref_ed_cb (ip4_address_t * out_addr, u16 out_port,
-                  ip4_address_t * eh_addr, u16 eh_port, u8 proto,
-                  u32 fib_index, u32 total_pkts, u64 total_bytes,
-                  u32 thread_index)
+static void
+nat44_ed_worker_db_free (snat_main_per_thread_data_t *tsm)
 {
-  snat_main_t *sm = &snat_main;
-  nat_ed_ses_key_t key;
-  clib_bihash_kv_16_8_t kv, value;
-  snat_session_t *s;
-  snat_main_per_thread_data_t *tsm;
+  pool_free (tsm->sessions);
+  pool_free (tsm->lru_pool);
 
-  tsm = vec_elt_at_index (sm->per_thread_data, thread_index);
-
-  key.l_addr.as_u32 = out_addr->as_u32;
-  key.l_port = out_port;
-  key.r_addr.as_u32 = eh_addr->as_u32;
-  key.r_port = eh_port;
-  key.proto = proto;
-  key.fib_index = fib_index;
-  kv.key[0] = key.as_u64[0];
-  kv.key[1] = key.as_u64[1];
-  if (clib_bihash_search_16_8 (&tsm->out2in_ed, &kv, &value))
-    return;
+  vec_free (tsm->per_vrf_sessions_vec);
 
-  s = pool_elt_at_index (tsm->sessions, value.value);
-  s->total_pkts = total_pkts;
-  s->total_bytes = total_bytes;
+  // TODO: resolve static mappings (put only to !ED)
+  pool_free (tsm->list_pool);
+  pool_free (tsm->users);
+  clib_bihash_free_8_8 (&tsm->user_hash);
 }
 
-static clib_error_t *
-snat_config (vlib_main_t * vm, unformat_input_t * input)
+static void
+nat44_ed_db_free ()
 {
   snat_main_t *sm = &snat_main;
-  nat66_main_t *nm = &nat66_main;
-  //dslite_main_t *dm = &dslite_main;
   snat_main_per_thread_data_t *tsm;
 
-  u32 static_mapping_buckets = 1024;
-  uword static_mapping_memory_size = 64 << 20;
-
-  u32 nat64_bib_buckets = 1024;
-  u32 nat64_bib_memory_size = 128 << 20;
-
-  u32 nat64_st_buckets = 2048;
-  uword nat64_st_memory_size = 256 << 20;
-
-  u32 user_buckets = 128;
-  uword user_memory_size = 64 << 20;
-  u32 translation_buckets = 1024;
-  uword translation_memory_size = 128 << 20;
-
-  u32 max_translations_per_user = ~0;
+  pool_free (sm->static_mappings);
+  clib_bihash_free_16_8 (&sm->flow_hash);
+  clib_bihash_free_8_8 (&sm->static_mapping_by_local);
+  clib_bihash_free_8_8 (&sm->static_mapping_by_external);
 
-  u32 outside_vrf_id = 0;
-  u32 outside_ip6_vrf_id = 0;
-  u32 inside_vrf_id = 0;
-  u8 static_mapping_only = 0;
-  u8 static_mapping_connection_tracking = 0;
-
-  // configurable timeouts
-  u32 udp_timeout = SNAT_UDP_TIMEOUT;
-  u32 icmp_timeout = SNAT_ICMP_TIMEOUT;
-  u32 tcp_transitory_timeout = SNAT_TCP_TRANSITORY_TIMEOUT;
-  u32 tcp_established_timeout = SNAT_TCP_ESTABLISHED_TIMEOUT;
-
-  sm->deterministic = 0;
-  sm->out2in_dpo = 0;
-  sm->endpoint_dependent = 0;
-
-  while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
+  if (sm->pat)
     {
-      if (unformat
-         (input, "translation hash buckets %d", &translation_buckets))
-       ;
-      else if (unformat (input, "udp timeout %d", &udp_timeout))
-       ;
-      else if (unformat (input, "icmp timeout %d", &icmp_timeout))
-       ;
-      else if (unformat (input, "tcp transitory timeout %d",
-                        &tcp_transitory_timeout));
-      else if (unformat (input, "tcp established timeout %d",
-                        &tcp_established_timeout));
-      else if (unformat (input, "translation hash memory %d",
-                        &translation_memory_size));
-      else if (unformat (input, "user hash buckets %d", &user_buckets))
-       ;
-      else if (unformat (input, "user hash memory %d", &user_memory_size))
-       ;
-      else if (unformat (input, "max translations per user %d",
-                        &max_translations_per_user))
-       ;
-      else if (unformat (input, "outside VRF id %d", &outside_vrf_id))
-       ;
-      else if (unformat (input, "outside ip6 VRF id %d", &outside_ip6_vrf_id))
-       ;
-      else if (unformat (input, "inside VRF id %d", &inside_vrf_id))
-       ;
-      else if (unformat (input, "static mapping only"))
+      vec_foreach (tsm, sm->per_thread_data)
        {
-         static_mapping_only = 1;
-         if (unformat (input, "connection tracking"))
-           static_mapping_connection_tracking = 1;
+         nat44_ed_worker_db_free (tsm);
        }
-      else if (unformat (input, "deterministic"))
-       sm->deterministic = 1;
-      else if (unformat (input, "nat64 bib hash buckets %d",
-                        &nat64_bib_buckets))
-       ;
-      else if (unformat (input, "nat64 bib hash memory %d",
-                        &nat64_bib_memory_size))
-       ;
-      else
-       if (unformat (input, "nat64 st hash buckets %d", &nat64_st_buckets))
-       ;
-      else if (unformat (input, "nat64 st hash memory %d",
-                        &nat64_st_memory_size))
-       ;
-      else if (unformat (input, "out2in dpo"))
-       sm->out2in_dpo = 1;
-      //else if (unformat (input, "dslite ce"))
-      //dslite_set_ce (dm, 1);
-      else if (unformat (input, "endpoint-dependent"))
-       sm->endpoint_dependent = 1;
-      else
-       return clib_error_return (0, "unknown input '%U'",
-                                 format_unformat_error, input);
-    }
-
-  if (sm->deterministic && sm->endpoint_dependent)
-    return clib_error_return (0,
-                             "deterministic and endpoint-dependent modes are mutually exclusive");
-
-  if (static_mapping_only && (sm->deterministic || sm->endpoint_dependent))
-    return clib_error_return (0,
-                             "static mapping only mode available only for simple nat");
-
-  if (sm->out2in_dpo && (sm->deterministic || sm->endpoint_dependent))
-    return clib_error_return (0,
-                             "out2in dpo mode available only for simple nat");
-
-  /* optionally configurable timeouts for testing purposes */
-  sm->udp_timeout = udp_timeout;
-  sm->tcp_transitory_timeout = tcp_transitory_timeout;
-  sm->tcp_established_timeout = tcp_established_timeout;
-  sm->icmp_timeout = icmp_timeout;
-
-  sm->user_buckets = user_buckets;
-  sm->user_memory_size = user_memory_size;
-
-  sm->translation_buckets = translation_buckets;
-  sm->translation_memory_size = translation_memory_size;
-
-  /* do not exceed load factor 10 */
-  sm->max_translations = 10 * translation_buckets;
-  sm->max_translations_per_user = max_translations_per_user == ~0 ?
-    sm->max_translations : max_translations_per_user;
-
-  sm->outside_vrf_id = outside_vrf_id;
-  sm->outside_fib_index = fib_table_find_or_create_and_lock (FIB_PROTOCOL_IP4,
-                                                            outside_vrf_id,
-                                                            nat_fib_src_hi);
-  nm->outside_vrf_id = outside_ip6_vrf_id;
-  nm->outside_fib_index = fib_table_find_or_create_and_lock (FIB_PROTOCOL_IP6,
-                                                            outside_ip6_vrf_id,
-                                                            nat_fib_src_hi);
-  sm->inside_vrf_id = inside_vrf_id;
-  sm->inside_fib_index = fib_table_find_or_create_and_lock (FIB_PROTOCOL_IP4,
-                                                           inside_vrf_id,
-                                                           nat_fib_src_hi);
-  sm->static_mapping_only = static_mapping_only;
-  sm->static_mapping_connection_tracking = static_mapping_connection_tracking;
-
-  nat64_set_hash (nat64_bib_buckets, nat64_bib_memory_size, nat64_st_buckets,
-                 nat64_st_memory_size);
-
-  if (sm->deterministic)
-    {
-      sm->in2out_node_index = snat_det_in2out_node.index;
-      sm->in2out_output_node_index = ~0;
-      sm->out2in_node_index = snat_det_out2in_node.index;
-      sm->icmp_match_in2out_cb = icmp_match_in2out_det;
-      sm->icmp_match_out2in_cb = icmp_match_out2in_det;
     }
-  else
-    {
-      if (sm->endpoint_dependent)
-       {
-         sm->worker_in2out_cb = nat44_ed_get_worker_in2out_cb;
-         sm->worker_out2in_cb = nat44_ed_get_worker_out2in_cb;
-
-         sm->handoff_out2in_index = nat_pre_out2in_node.index;
-         sm->handoff_in2out_index = nat_pre_in2out_node.index;
-         sm->handoff_in2out_output_index = nat44_ed_in2out_output_node.index;
-
-         sm->in2out_node_index = nat44_ed_in2out_node.index;
-         sm->in2out_output_node_index = nat44_ed_in2out_output_node.index;
-         sm->out2in_node_index = nat44_ed_out2in_node.index;
-
-         sm->icmp_match_in2out_cb = icmp_match_in2out_ed;
-         sm->icmp_match_out2in_cb = icmp_match_out2in_ed;
-         nat_affinity_init (vm);
-         nat_ha_init (vm, nat_ha_sadd_ed_cb, nat_ha_sdel_ed_cb,
-                      nat_ha_sref_ed_cb);
-       }
-      else
-       {
-         sm->worker_in2out_cb = snat_get_worker_in2out_cb;
-         sm->worker_out2in_cb = snat_get_worker_out2in_cb;
-
-         sm->handoff_out2in_index = snat_out2in_node.index;
-         sm->handoff_in2out_index = snat_in2out_node.index;
-         sm->handoff_in2out_output_index = snat_in2out_output_node.index;
-
-         sm->in2out_node_index = snat_in2out_node.index;
-         sm->in2out_output_node_index = snat_in2out_output_node.index;
-         sm->out2in_node_index = snat_out2in_node.index;
-         sm->icmp_match_in2out_cb = icmp_match_in2out_slow;
-         sm->icmp_match_out2in_cb = icmp_match_out2in_slow;
-         nat_ha_init (vm, nat_ha_sadd_cb, nat_ha_sdel_cb, nat_ha_sref_cb);
-       }
-      if (!static_mapping_only ||
-         (static_mapping_only && static_mapping_connection_tracking))
-       {
-          /* *INDENT-OFF* */
-          vec_foreach (tsm, sm->per_thread_data)
-            {
-              pool_alloc (tsm->sessions, sm->max_translations);
-              pool_alloc (tsm->list_pool, sm->max_translations);
-              pool_alloc (tsm->global_lru_pool, sm->max_translations);
-
-              dlist_elt_t *head;
-              pool_get (tsm->global_lru_pool, head);
-              tsm->global_lru_head_index = head - tsm->global_lru_pool;
-              clib_dlist_init (tsm->global_lru_pool,
-                               tsm->global_lru_head_index);
+}
 
-              if (sm->endpoint_dependent)
-                {
-                  clib_bihash_init_16_8 (&tsm->in2out_ed, "in2out-ed",
-                                         translation_buckets,
-                                         translation_memory_size);
-                  clib_bihash_set_kvp_format_fn_16_8 (&tsm->in2out_ed,
-                                                      format_ed_session_kvp);
-
-                  clib_bihash_init_16_8 (&tsm->out2in_ed, "out2in-ed",
-                                         translation_buckets,
-                                         translation_memory_size);
-                  clib_bihash_set_kvp_format_fn_16_8 (&tsm->out2in_ed,
-                                                      format_ed_session_kvp);
-                }
-              else
-                {
-                  clib_bihash_init_8_8 (&tsm->in2out, "in2out",
-                                        translation_buckets,
-                                        translation_memory_size);
-                  clib_bihash_set_kvp_format_fn_8_8 (&tsm->in2out,
-                                                     format_session_kvp);
-
-                  clib_bihash_init_8_8 (&tsm->out2in, "out2in",
-                                        translation_buckets,
-                                        translation_memory_size);
-                  clib_bihash_set_kvp_format_fn_8_8 (&tsm->out2in,
-                                                     format_session_kvp);
-                }
+void
+nat44_ed_sessions_clear ()
+{
+  snat_main_t *sm = &snat_main;
+  snat_main_per_thread_data_t *tsm;
 
-              clib_bihash_init_8_8 (&tsm->user_hash, "users", user_buckets,
-                                    user_memory_size);
-              clib_bihash_set_kvp_format_fn_8_8 (&tsm->user_hash,
-                                                 format_user_kvp);
-            }
-          /* *INDENT-ON* */
+  reinit_ed_flow_hash ();
 
-       }
-      else
+  if (sm->pat)
+    {
+      vec_foreach (tsm, sm->per_thread_data)
        {
-         sm->icmp_match_in2out_cb = icmp_match_in2out_fast;
-         sm->icmp_match_out2in_cb = icmp_match_out2in_fast;
+
+         nat44_ed_worker_db_free (tsm);
+         nat44_ed_worker_db_init (tsm, sm->max_translations_per_thread,
+                                  sm->translation_buckets, sm->user_buckets);
        }
-      clib_bihash_init_8_8 (&sm->static_mapping_by_local,
-                           "static_mapping_by_local", static_mapping_buckets,
-                           static_mapping_memory_size);
-      clib_bihash_set_kvp_format_fn_8_8 (&sm->static_mapping_by_local,
-                                        format_static_mapping_kvp);
-
-      clib_bihash_init_8_8 (&sm->static_mapping_by_external,
-                           "static_mapping_by_external",
-                           static_mapping_buckets,
-                           static_mapping_memory_size);
-      clib_bihash_set_kvp_format_fn_8_8 (&sm->static_mapping_by_external,
-                                        format_static_mapping_kvp);
     }
 
-  return 0;
+  // TODO: function for reset counters
+  vlib_zero_simple_counter (&sm->total_users, 0);
+  vlib_zero_simple_counter (&sm->total_sessions, 0);
+  vlib_zero_simple_counter (&sm->user_limit_reached, 0);
 }
 
-VLIB_CONFIG_FUNCTION (snat_config, "nat");
+void
+nat44_sessions_clear ()
+{
+  snat_main_t *sm = &snat_main;
+
+  if (sm->endpoint_dependent)
+    nat44_ed_sessions_clear ();
+  else
+    nat44_ei_sessions_clear ();
+}
 
 static void
 nat_ip4_add_del_addr_only_sm_cb (ip4_main_t * im,
@@ -4154,11 +3607,13 @@ nat_ip4_add_del_addr_only_sm_cb (ip4_main_t * im,
   snat_main_t *sm = &snat_main;
   snat_static_map_resolve_t *rp;
   snat_static_mapping_t *m;
-  snat_session_key_t m_key;
   clib_bihash_kv_8_8_t kv, value;
   int i, rv;
   ip4_address_t l_addr;
 
+  if (!sm->enabled)
+    return;
+
   for (i = 0; i < vec_len (sm->to_resolve); i++)
     {
       rp = sm->to_resolve + i;
@@ -4171,11 +3626,8 @@ nat_ip4_add_del_addr_only_sm_cb (ip4_main_t * im,
   return;
 
 match:
-  m_key.addr.as_u32 = address->as_u32;
-  m_key.port = rp->addr_only ? 0 : rp->e_port;
-  m_key.protocol = rp->addr_only ? 0 : rp->proto;
-  m_key.fib_index = sm->outside_fib_index;
-  kv.key = m_key.as_u64;
+  init_nat_k (&kv, *address, rp->addr_only ? 0 : rp->e_port,
+             sm->outside_fib_index, rp->addr_only ? 0 : rp->proto);
   if (clib_bihash_search_8_8 (&sm->static_mapping_by_external, &kv, &value))
     m = 0;
   else
@@ -4206,7 +3658,8 @@ match:
                                rp->vrf_id,
                                rp->addr_only, ~0 /* sw_if_index */ ,
                                rp->proto, !is_delete, rp->twice_nat,
-                               rp->out2in_only, rp->tag, rp->identity_nat);
+                               rp->out2in_only, rp->tag, rp->identity_nat,
+                               rp->pool_addr, rp->exact);
   if (rv)
     nat_elog_notice_X1 ("snat_add_static_mapping returned %d", "i4", rv);
 }
@@ -4227,6 +3680,9 @@ snat_ip4_add_del_interface_address_cb (ip4_main_t * im,
   u8 twice_nat = 0;
   snat_address_t *addresses = sm->addresses;
 
+  if (!sm->enabled)
+    return;
+
   for (i = 0; i < vec_len (sm->auto_add_sw_if_indices); i++)
     {
       if (sw_if_index == sm->auto_add_sw_if_indices[i])
@@ -4267,17 +3723,11 @@ match:
              else
                l_addr.as_u32 = rp->l_addr.as_u32;
              /* Add the static mapping */
-             rv = snat_add_static_mapping (l_addr,
-                                           address[0],
-                                           rp->l_port,
-                                           rp->e_port,
-                                           rp->vrf_id,
-                                           rp->addr_only,
-                                           ~0 /* sw_if_index */ ,
-                                           rp->proto,
-                                           rp->is_add, rp->twice_nat,
-                                           rp->out2in_only, rp->tag,
-                                           rp->identity_nat);
+             rv = snat_add_static_mapping (
+               l_addr, address[0], rp->l_port, rp->e_port, rp->vrf_id,
+               rp->addr_only, ~0 /* sw_if_index */, rp->proto, 1,
+               rp->twice_nat, rp->out2in_only, rp->tag, rp->identity_nat,
+               rp->pool_addr, rp->exact);
              if (rv)
                nat_elog_notice_X1 ("snat_add_static_mapping returned %d",
                                    "i4", rv);
@@ -4292,7 +3742,6 @@ match:
     }
 }
 
-
 int
 snat_add_interface_address (snat_main_t * sm, u32 sw_if_index, int is_del,
                            u8 twice_nat)
@@ -4361,57 +3810,12 @@ snat_add_interface_address (snat_main_t * sm, u32 sw_if_index, int is_del,
   return 0;
 }
 
-int
-nat44_del_session (snat_main_t * sm, ip4_address_t * addr, u16 port,
-                  snat_protocol_t proto, u32 vrf_id, int is_in)
-{
-  snat_main_per_thread_data_t *tsm;
-  clib_bihash_kv_8_8_t kv, value;
-  ip4_header_t ip;
-  u32 fib_index = fib_table_find (FIB_PROTOCOL_IP4, vrf_id);
-  snat_session_key_t key;
-  snat_session_t *s;
-  clib_bihash_8_8_t *t;
-
-  if (sm->endpoint_dependent)
-    return VNET_API_ERROR_UNSUPPORTED;
-
-  ip.dst_address.as_u32 = ip.src_address.as_u32 = addr->as_u32;
-  if (sm->num_workers > 1)
-    tsm =
-      vec_elt_at_index (sm->per_thread_data,
-                       sm->worker_in2out_cb (&ip, fib_index, 0));
-  else
-    tsm = vec_elt_at_index (sm->per_thread_data, sm->num_workers);
-
-  key.addr.as_u32 = addr->as_u32;
-  key.port = clib_host_to_net_u16 (port);
-  key.protocol = proto;
-  key.fib_index = fib_index;
-  kv.key = key.as_u64;
-  t = is_in ? &tsm->in2out : &tsm->out2in;
-  if (!clib_bihash_search_8_8 (t, &kv, &value))
-    {
-      if (pool_is_free_index (tsm->sessions, value.value))
-       return VNET_API_ERROR_UNSPECIFIED;
-
-      s = pool_elt_at_index (tsm->sessions, value.value);
-      nat_free_session_data (sm, s, tsm - sm->per_thread_data, 0);
-      nat44_delete_session (sm, s, tsm - sm->per_thread_data);
-      return 0;
-    }
-
-  return VNET_API_ERROR_NO_SUCH_ENTRY;
-}
-
 int
 nat44_del_ed_session (snat_main_t * sm, ip4_address_t * addr, u16 port,
                      ip4_address_t * eh_addr, u16 eh_port, u8 proto,
                      u32 vrf_id, int is_in)
 {
   ip4_header_t ip;
-  clib_bihash_16_8_t *t;
-  nat_ed_ses_key_t key;
   clib_bihash_kv_16_8_t kv, value;
   u32 fib_index = fib_table_find (FIB_PROTOCOL_IP4, vrf_id);
   snat_session_t *s;
@@ -4428,58 +3832,20 @@ nat44_del_ed_session (snat_main_t * sm, ip4_address_t * addr, u16 port,
   else
     tsm = vec_elt_at_index (sm->per_thread_data, sm->num_workers);
 
-  t = is_in ? &tsm->in2out_ed : &tsm->out2in_ed;
-  key.l_addr.as_u32 = addr->as_u32;
-  key.r_addr.as_u32 = eh_addr->as_u32;
-  key.l_port = clib_host_to_net_u16 (port);
-  key.r_port = clib_host_to_net_u16 (eh_port);
-  key.proto = proto;
-  key.fib_index = fib_index;
-  kv.key[0] = key.as_u64[0];
-  kv.key[1] = key.as_u64[1];
-  if (clib_bihash_search_16_8 (t, &kv, &value))
-    return VNET_API_ERROR_NO_SUCH_ENTRY;
+  init_ed_k (&kv, *addr, port, *eh_addr, eh_port, fib_index, proto);
+  if (clib_bihash_search_16_8 (&sm->flow_hash, &kv, &value))
+    {
+      return VNET_API_ERROR_NO_SUCH_ENTRY;
+    }
 
-  if (pool_is_free_index (tsm->sessions, value.value))
+  if (pool_is_free_index (tsm->sessions, ed_value_get_session_index (&value)))
     return VNET_API_ERROR_UNSPECIFIED;
-  s = pool_elt_at_index (tsm->sessions, value.value);
+  s = pool_elt_at_index (tsm->sessions, ed_value_get_session_index (&value));
   nat_free_session_data (sm, s, tsm - sm->per_thread_data, 0);
-  nat44_ed_delete_session (sm, s, tsm - sm->per_thread_data, 1);
+  nat_ed_session_delete (sm, s, tsm - sm->per_thread_data, 1);
   return 0;
 }
 
-void
-nat_set_alloc_addr_and_port_mape (u16 psid, u16 psid_offset, u16 psid_length)
-{
-  snat_main_t *sm = &snat_main;
-
-  sm->addr_and_port_alloc_alg = NAT_ADDR_AND_PORT_ALLOC_ALG_MAPE;
-  sm->alloc_addr_and_port = nat_alloc_addr_and_port_mape;
-  sm->psid = psid;
-  sm->psid_offset = psid_offset;
-  sm->psid_length = psid_length;
-}
-
-void
-nat_set_alloc_addr_and_port_range (u16 start_port, u16 end_port)
-{
-  snat_main_t *sm = &snat_main;
-
-  sm->addr_and_port_alloc_alg = NAT_ADDR_AND_PORT_ALLOC_ALG_RANGE;
-  sm->alloc_addr_and_port = nat_alloc_addr_and_port_range;
-  sm->start_port = start_port;
-  sm->end_port = end_port;
-}
-
-void
-nat_set_alloc_addr_and_port_default (void)
-{
-  snat_main_t *sm = &snat_main;
-
-  sm->addr_and_port_alloc_alg = NAT_ADDR_AND_PORT_ALLOC_ALG_DEFAULT;
-  sm->alloc_addr_and_port = nat_alloc_addr_and_port_default;
-}
-
 VLIB_NODE_FN (nat_default_node) (vlib_main_t * vm,
                                 vlib_node_runtime_t * node,
                                 vlib_frame_t * frame)
@@ -4498,17 +3864,349 @@ VLIB_REGISTER_NODE (nat_default_node) = {
   .next_nodes = {
     [NAT_NEXT_DROP] = "error-drop",
     [NAT_NEXT_ICMP_ERROR] = "ip4-icmp-error",
-    [NAT_NEXT_IN2OUT_PRE] = "nat-pre-in2out",
-    [NAT_NEXT_OUT2IN_PRE] = "nat-pre-out2in",
     [NAT_NEXT_IN2OUT_ED_FAST_PATH] = "nat44-ed-in2out",
     [NAT_NEXT_IN2OUT_ED_SLOW_PATH] = "nat44-ed-in2out-slowpath",
+    [NAT_NEXT_IN2OUT_ED_OUTPUT_FAST_PATH] = "nat44-ed-in2out-output",
     [NAT_NEXT_IN2OUT_ED_OUTPUT_SLOW_PATH] = "nat44-ed-in2out-output-slowpath",
     [NAT_NEXT_OUT2IN_ED_FAST_PATH] = "nat44-ed-out2in",
     [NAT_NEXT_OUT2IN_ED_SLOW_PATH] = "nat44-ed-out2in-slowpath",
+    [NAT_NEXT_IN2OUT_CLASSIFY] = "nat44-in2out-worker-handoff",
+    [NAT_NEXT_OUT2IN_CLASSIFY] = "nat44-out2in-worker-handoff",
   },
 };
 /* *INDENT-ON* */
 
+void
+nat_6t_l3_l4_csum_calc (nat_6t_flow_t *f)
+{
+  f->l3_csum_delta = 0;
+  f->l4_csum_delta = 0;
+  if (f->ops & NAT_FLOW_OP_SADDR_REWRITE &&
+      f->rewrite.saddr.as_u32 != f->match.saddr.as_u32)
+    {
+      f->l3_csum_delta =
+       ip_csum_add_even (f->l3_csum_delta, f->rewrite.saddr.as_u32);
+      f->l3_csum_delta =
+       ip_csum_sub_even (f->l3_csum_delta, f->match.saddr.as_u32);
+    }
+  else
+    {
+      f->rewrite.saddr.as_u32 = f->match.saddr.as_u32;
+    }
+  if (f->ops & NAT_FLOW_OP_DADDR_REWRITE &&
+      f->rewrite.daddr.as_u32 != f->match.daddr.as_u32)
+    {
+      f->l3_csum_delta =
+       ip_csum_add_even (f->l3_csum_delta, f->rewrite.daddr.as_u32);
+      f->l3_csum_delta =
+       ip_csum_sub_even (f->l3_csum_delta, f->match.daddr.as_u32);
+    }
+  else
+    {
+      f->rewrite.daddr.as_u32 = f->match.daddr.as_u32;
+    }
+  if (f->ops & NAT_FLOW_OP_SPORT_REWRITE && f->rewrite.sport != f->match.sport)
+    {
+      f->l4_csum_delta = ip_csum_add_even (f->l4_csum_delta, f->rewrite.sport);
+      f->l4_csum_delta = ip_csum_sub_even (f->l4_csum_delta, f->match.sport);
+    }
+  else
+    {
+      f->rewrite.sport = f->match.sport;
+    }
+  if (f->ops & NAT_FLOW_OP_DPORT_REWRITE && f->rewrite.dport != f->match.dport)
+    {
+      f->l4_csum_delta = ip_csum_add_even (f->l4_csum_delta, f->rewrite.dport);
+      f->l4_csum_delta = ip_csum_sub_even (f->l4_csum_delta, f->match.dport);
+    }
+  else
+    {
+      f->rewrite.dport = f->match.dport;
+    }
+  if (f->ops & NAT_FLOW_OP_ICMP_ID_REWRITE &&
+      f->rewrite.icmp_id != f->match.icmp_id)
+    {
+      f->l4_csum_delta =
+       ip_csum_add_even (f->l4_csum_delta, f->rewrite.icmp_id);
+      f->l4_csum_delta = ip_csum_sub_even (f->l4_csum_delta, f->match.icmp_id);
+    }
+  else
+    {
+      f->rewrite.icmp_id = f->match.icmp_id;
+    }
+  if (f->ops & NAT_FLOW_OP_TXFIB_REWRITE)
+    {
+    }
+  else
+    {
+      f->rewrite.fib_index = f->match.fib_index;
+    }
+}
+
+static_always_inline int nat_6t_flow_icmp_translate (snat_main_t *sm,
+                                                    vlib_buffer_t *b,
+                                                    ip4_header_t *ip,
+                                                    nat_6t_flow_t *f);
+
+static_always_inline void
+nat_6t_flow_ip4_translate (snat_main_t *sm, vlib_buffer_t *b, ip4_header_t *ip,
+                          nat_6t_flow_t *f, nat_protocol_t proto,
+                          int is_icmp_inner_ip4)
+{
+  udp_header_t *udp = ip4_next_header (ip);
+  tcp_header_t *tcp = (tcp_header_t *) udp;
+
+  if ((NAT_PROTOCOL_TCP == proto || NAT_PROTOCOL_UDP == proto) &&
+      !vnet_buffer (b)->ip.reass.is_non_first_fragment)
+    {
+      if (!is_icmp_inner_ip4)
+       { // regular case
+         ip->src_address = f->rewrite.saddr;
+         ip->dst_address = f->rewrite.daddr;
+         udp->src_port = f->rewrite.sport;
+         udp->dst_port = f->rewrite.dport;
+       }
+      else
+       { // icmp inner ip4 - reversed saddr/daddr
+         ip->src_address = f->rewrite.daddr;
+         ip->dst_address = f->rewrite.saddr;
+         udp->src_port = f->rewrite.dport;
+         udp->dst_port = f->rewrite.sport;
+       }
+
+      if (NAT_PROTOCOL_TCP == proto)
+       {
+         ip_csum_t tcp_sum = tcp->checksum;
+         tcp_sum = ip_csum_sub_even (tcp_sum, f->l3_csum_delta);
+         tcp_sum = ip_csum_sub_even (tcp_sum, f->l4_csum_delta);
+         mss_clamping (sm->mss_clamping, tcp, &tcp_sum);
+         tcp->checksum = ip_csum_fold (tcp_sum);
+       }
+      else if (proto == NAT_PROTOCOL_UDP && udp->checksum)
+       {
+         ip_csum_t udp_sum = udp->checksum;
+         udp_sum = ip_csum_sub_even (udp_sum, f->l3_csum_delta);
+         udp_sum = ip_csum_sub_even (udp_sum, f->l4_csum_delta);
+         udp->checksum = ip_csum_fold (udp_sum);
+       }
+    }
+  else
+    {
+      if (!is_icmp_inner_ip4)
+       { // regular case
+         ip->src_address = f->rewrite.saddr;
+         ip->dst_address = f->rewrite.daddr;
+       }
+      else
+       { // icmp inner ip4 - reversed saddr/daddr
+         ip->src_address = f->rewrite.daddr;
+         ip->dst_address = f->rewrite.saddr;
+       }
+    }
+
+  ip_csum_t ip_sum = ip->checksum;
+  ip_sum = ip_csum_sub_even (ip_sum, f->l3_csum_delta);
+  ip->checksum = ip_csum_fold (ip_sum);
+  ASSERT (ip->checksum == ip4_header_checksum (ip));
+}
+
+static_always_inline int
+nat_6t_flow_icmp_translate (snat_main_t *sm, vlib_buffer_t *b,
+                           ip4_header_t *ip, nat_6t_flow_t *f)
+{
+  if (IP_PROTOCOL_ICMP != ip->protocol)
+    return NAT_ED_TRNSL_ERR_TRANSLATION_FAILED;
+
+  icmp46_header_t *icmp = ip4_next_header (ip);
+  icmp_echo_header_t *echo = (icmp_echo_header_t *) (icmp + 1);
+
+  if ((!vnet_buffer (b)->ip.reass.is_non_first_fragment))
+    {
+      if (icmp->checksum == 0)
+       icmp->checksum = 0xffff;
+
+      if (!icmp_type_is_error_message (icmp->type))
+       {
+         if ((f->ops & NAT_FLOW_OP_ICMP_ID_REWRITE) &&
+             (f->rewrite.icmp_id != echo->identifier))
+           {
+             ip_csum_t sum = icmp->checksum;
+             sum = ip_csum_update (sum, echo->identifier, f->rewrite.icmp_id,
+                                   icmp_echo_header_t,
+                                   identifier /* changed member */);
+             echo->identifier = f->rewrite.icmp_id;
+             icmp->checksum = ip_csum_fold (sum);
+           }
+       }
+      else
+       {
+         // errors are not fragmented
+         ip4_header_t *inner_ip = (ip4_header_t *) (echo + 1);
+
+         if (!ip4_header_checksum_is_valid (inner_ip))
+           {
+             return NAT_ED_TRNSL_ERR_TRANSLATION_FAILED;
+           }
+
+         nat_protocol_t inner_proto =
+           ip_proto_to_nat_proto (inner_ip->protocol);
+
+         ip_csum_t icmp_sum = icmp->checksum;
+
+         switch (inner_proto)
+           {
+           case NAT_PROTOCOL_UDP:
+           case NAT_PROTOCOL_TCP:
+             nat_6t_flow_ip4_translate (sm, b, inner_ip, f, inner_proto,
+                                        1 /* is_icmp_inner_ip4 */);
+             icmp_sum = ip_csum_sub_even (icmp_sum, f->l3_csum_delta);
+             icmp->checksum = ip_csum_fold (icmp_sum);
+             break;
+           case NAT_PROTOCOL_ICMP:
+             if (f->ops & NAT_FLOW_OP_ICMP_ID_REWRITE)
+               {
+                 icmp46_header_t *inner_icmp = ip4_next_header (inner_ip);
+                 icmp_echo_header_t *inner_echo =
+                   (icmp_echo_header_t *) (inner_icmp + 1);
+                 if (f->rewrite.icmp_id != inner_echo->identifier)
+                   {
+                     ip_csum_t sum = icmp->checksum;
+                     sum = ip_csum_update (
+                       sum, inner_echo->identifier, f->rewrite.icmp_id,
+                       icmp_echo_header_t, identifier /* changed member */);
+                     icmp->checksum = ip_csum_fold (sum);
+                     ip_csum_t inner_sum = inner_icmp->checksum;
+                     inner_sum = ip_csum_update (
+                       sum, inner_echo->identifier, f->rewrite.icmp_id,
+                       icmp_echo_header_t, identifier /* changed member */);
+                     inner_icmp->checksum = ip_csum_fold (inner_sum);
+                     inner_echo->identifier = f->rewrite.icmp_id;
+                   }
+               }
+             break;
+           default:
+             clib_warning ("unexpected NAT protocol value `%d'", inner_proto);
+             return NAT_ED_TRNSL_ERR_TRANSLATION_FAILED;
+           }
+       }
+    }
+  return NAT_ED_TRNSL_ERR_SUCCESS;
+}
+
+nat_translation_error_e
+nat_6t_flow_buf_translate (snat_main_t *sm, vlib_buffer_t *b, ip4_header_t *ip,
+                          nat_6t_flow_t *f, nat_protocol_t proto,
+                          int is_output_feature)
+{
+  if (!is_output_feature && f->ops & NAT_FLOW_OP_TXFIB_REWRITE)
+    {
+      vnet_buffer (b)->sw_if_index[VLIB_TX] = f->rewrite.fib_index;
+    }
+
+  nat_6t_flow_ip4_translate (sm, b, ip, f, proto, 0 /* is_icmp_inner_ip4 */);
+
+  if (NAT_PROTOCOL_ICMP == proto)
+    {
+      return nat_6t_flow_icmp_translate (sm, b, ip, f);
+    }
+
+  return NAT_ED_TRNSL_ERR_SUCCESS;
+}
+
+u8 *
+format_nat_6t (u8 *s, va_list *args)
+{
+  nat_6t_t *t = va_arg (*args, nat_6t_t *);
+
+  s = format (s, "saddr %U sport %u daddr %U dport %u proto %U fib_idx %u",
+             format_ip4_address, t->saddr.as_u8,
+             clib_net_to_host_u16 (t->sport), format_ip4_address,
+             t->daddr.as_u8, clib_net_to_host_u16 (t->dport),
+             format_ip_protocol, t->proto, t->fib_index);
+  return s;
+}
+
+u8 *
+format_nat_ed_translation_error (u8 *s, va_list *args)
+{
+  nat_translation_error_e e = va_arg (*args, nat_translation_error_e);
+
+  switch (e)
+    {
+    case NAT_ED_TRNSL_ERR_SUCCESS:
+      s = format (s, "success");
+      break;
+    case NAT_ED_TRNSL_ERR_TRANSLATION_FAILED:
+      s = format (s, "translation-failed");
+      break;
+    case NAT_ED_TRNSL_ERR_FLOW_MISMATCH:
+      s = format (s, "flow-mismatch");
+      break;
+    }
+  return s;
+}
+
+u8 *
+format_nat_6t_flow (u8 *s, va_list *args)
+{
+  nat_6t_flow_t *f = va_arg (*args, nat_6t_flow_t *);
+
+  s = format (s, "match: %U ", format_nat_6t, &f->match);
+  int r = 0;
+  if (f->ops & NAT_FLOW_OP_SADDR_REWRITE)
+    {
+      s = format (s, "rewrite: saddr %U ", format_ip4_address,
+                 f->rewrite.saddr.as_u8);
+      r = 1;
+    }
+  if (f->ops & NAT_FLOW_OP_SPORT_REWRITE)
+    {
+      if (!r)
+       {
+         s = format (s, "rewrite: ");
+         r = 1;
+       }
+      s = format (s, "sport %u ", clib_net_to_host_u16 (f->rewrite.sport));
+    }
+  if (f->ops & NAT_FLOW_OP_DADDR_REWRITE)
+    {
+      if (!r)
+       {
+         s = format (s, "rewrite: ");
+         r = 1;
+       }
+      s = format (s, "daddr %U ", format_ip4_address, f->rewrite.daddr.as_u8);
+    }
+  if (f->ops & NAT_FLOW_OP_DPORT_REWRITE)
+    {
+      if (!r)
+       {
+         s = format (s, "rewrite: ");
+         r = 1;
+       }
+      s = format (s, "dport %u ", clib_net_to_host_u16 (f->rewrite.dport));
+    }
+  if (f->ops & NAT_FLOW_OP_ICMP_ID_REWRITE)
+    {
+      if (!r)
+       {
+         s = format (s, "rewrite: ");
+         r = 1;
+       }
+      s = format (s, "icmp-id %u ", clib_net_to_host_u16 (f->rewrite.icmp_id));
+    }
+  if (f->ops & NAT_FLOW_OP_TXFIB_REWRITE)
+    {
+      if (!r)
+       {
+         s = format (s, "rewrite: ");
+         r = 1;
+       }
+      s = format (s, "txfib %u ", f->rewrite.fib_index);
+    }
+  return s;
+}
+
 /*
  * fd.io coding-style-patch-verification: ON
  *