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diff --git a/src/plugins/nat/nat44/inlines.h b/src/plugins/nat/nat44/inlines.h
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+++ b/src/plugins/nat/nat44/inlines.h
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+/*
+ * Copyright (c) 2020 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+/**
+ * @brief The NAT44 inline functions
+ */
+
+#ifndef included_nat44_inlines_h__
+#define included_nat44_inlines_h__
+
+#include <vnet/fib/ip4_fib.h>
+#include <nat/nat.h>
+
+static_always_inline u8
+nat44_maximum_sessions_exceeded (snat_main_t * sm, u32 thread_index)
+{
+  if (pool_elts (sm->per_thread_data[thread_index].sessions) >=
+      sm->max_translations)
+    return 1;
+  return 0;
+}
+
+static_always_inline void
+nat44_session_cleanup (snat_session_t * s, u32 thread_index)
+{
+  snat_main_t *sm = &snat_main;
+
+  nat_free_session_data (sm, s, thread_index, 0);
+  nat44_delete_session (sm, s, thread_index);
+}
+
+static_always_inline void
+nat44_user_try_cleanup (snat_user_t * u, u32 thread_index, f64 now)
+{
+  dlist_elt_t *elt;
+  snat_session_t *s;
+  u64 sess_timeout_time;
+
+  snat_main_t *sm = &snat_main;
+  snat_main_per_thread_data_t *tsm = &sm->per_thread_data[thread_index];
+
+  // get head
+  elt = pool_elt_at_index (tsm->list_pool,
+			   u->sessions_per_user_list_head_index);
+  // get first element
+  elt = pool_elt_at_index (tsm->list_pool, elt->next);
+
+  while (elt->value != ~0)
+    {
+      s = pool_elt_at_index (tsm->sessions, elt->value);
+      elt = pool_elt_at_index (tsm->list_pool, elt->next);
+
+      sess_timeout_time = s->last_heard +
+	(f64) nat44_session_get_timeout (sm, s);
+
+      if (now < sess_timeout_time)
+	continue;
+
+      nat44_session_cleanup (s, thread_index);
+    }
+}
+
+static_always_inline void
+nat44_session_try_cleanup (ip4_address_t * addr,
+			   u32 fib_index, u32 thread_index, f64 now)
+{
+  snat_user_t *u = 0;
+  snat_user_key_t user_key;
+  clib_bihash_kv_8_8_t kv, value;
+
+  snat_main_t *sm = &snat_main;
+  snat_main_per_thread_data_t *tsm = &sm->per_thread_data[thread_index];
+
+  user_key.addr.as_u32 = addr->as_u32;
+  user_key.fib_index = fib_index;
+  kv.key = user_key.as_u64;
+
+  // lookup user for this traffic
+  if (PREDICT_FALSE (clib_bihash_search_8_8 (&tsm->user_hash, &kv, &value)))
+    {
+      // there is still place and a new user can be created
+      if (PREDICT_TRUE (pool_elts (tsm->sessions) < sm->max_translations))
+	return;
+
+      // there is no place so we try to cleanup all users in this thread
+      /* *INDENT-OFF* */
+      pool_foreach (u, tsm->users,
+      ({
+        nat44_user_try_cleanup (u, thread_index, now);
+      }));
+      /* *INDENT-ON* */
+      return;
+    }
+
+  // each time user creates a new session we try to cleanup expired sessions
+  nat44_user_try_cleanup (pool_elt_at_index (tsm->users, value.value),
+			  thread_index, now);
+}
+
+#endif /* included_nat44_inlines_h__ */
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */