diff --git a/utils/empty-policy.h b/utils/empty-policy.h
index c5f324c..a04507d 100644
--- a/utils/empty-policy.h
+++ b/utils/empty-policy.h
@@ -24,6 +24,9 @@
 namespace ndnSIM
 {
 
+/**
+ * @brief Traits for empty (bogus) replacement policy
+ */
 struct empty_policy_traits
 {
   typedef void* policy_hook_type;
diff --git a/utils/fifo-policy.h b/utils/fifo-policy.h
index 2dccbe4..7a61721 100644
--- a/utils/fifo-policy.h
+++ b/utils/fifo-policy.h
@@ -27,6 +27,9 @@
 namespace ndnSIM
 {
 
+/**
+ * @brief Traits for First In First Out replacement policy
+ */
 struct fifo_policy_traits
 {
   struct policy_hook_type : public boost::intrusive::list_member_hook<> {};
diff --git a/utils/lru-policy.h b/utils/lru-policy.h
index 077d602..92a9953 100644
--- a/utils/lru-policy.h
+++ b/utils/lru-policy.h
@@ -27,6 +27,9 @@
 namespace ndnSIM
 {
 
+/**
+ * @brief Traits for Least Recently Used replacement policy
+ */
 struct lru_policy_traits
 {
   struct policy_hook_type : public boost::intrusive::list_member_hook<> {};
diff --git a/utils/payload-policy.h b/utils/payload-policy.h
new file mode 100644
index 0000000..5eb384a
--- /dev/null
+++ b/utils/payload-policy.h
@@ -0,0 +1,131 @@
+/* -*-  Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * Copyright (c) 2011 University of California, Los Angeles
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation;
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ * Author: Alexander Afanasyev <alexander.afanasyev@ucla.edu>
+ */
+
+#ifndef PAYLOAD_POLICY_H_
+#define PAYLOAD_POLICY_H_
+
+#include <boost/intrusive/options.hpp>
+#include <boost/intrusive/list.hpp>
+
+namespace ndnSIM
+{
+
+/**
+ * @brief Traits for policy that keeps items in a sorted order using payload member
+ */
+template<class Member>
+struct payload_policy_traits
+{
+  struct policy_hook_type : public boost::intrusive::set_member_hook<> {};
+
+  template<class Container>
+  struct container_hook
+  {
+    typedef boost::intrusive::member_hook< Container,
+                                           policy_hook_type,
+                                           &Container::policy_hook_ > type;
+  };
+
+  template<class Base,
+           class Container,
+           class Hook>
+  struct policy 
+  {
+    typedef typename boost::intrusive::list< Container, Hook > policy_container;
+    
+    // could be just typedef
+    class type : public policy_container
+    {
+    public:
+      typedef Container parent_trie;
+    
+      type (Base &base)
+        : base_ (base)
+        , max_size_ (100)
+      {
+      }
+
+      inline void
+      update (typename parent_trie::iterator item)
+      {
+        // do relocation
+        policy_container::splice (policy_container::end (),
+                                  *this,
+                                  policy_container::s_iterator_to (*item));
+      }
+  
+      inline bool
+      insert (typename parent_trie::iterator item)
+      {
+        if (policy_container::size () >= max_size_)
+          {
+            base_.erase (&(*policy_container::begin ()));
+          }
+      
+        policy_container::push_back (*item);
+        return true;
+      }
+  
+      inline void
+      lookup (typename parent_trie::iterator item)
+      {
+        // do relocation
+        policy_container::splice (policy_container::end (),
+                                  *this,
+                                  policy_container::s_iterator_to (*item));
+      }
+  
+      inline void
+      erase (typename parent_trie::iterator item)
+      {
+        policy_container::erase (policy_container::s_iterator_to (*item));
+      }
+
+      inline void
+      clear ()
+      {
+        policy_container::clear ();
+      }
+
+      inline void
+      set_max_size (size_t max_size)
+      {
+        max_size_ = max_size;
+      }
+
+      inline size_t
+      get_max_size () const
+      {
+        return max_size_;
+      }
+
+    private:
+      type () : base_(*((Base*)0)) { };
+
+    private:
+      Base &base_;
+      size_t max_size_;
+    };
+  };
+};
+
+} // ndnSIM
+
+#endif // PAYLOAD_POLICY_H
diff --git a/utils/persistent-policy.h b/utils/persistent-policy.h
new file mode 100644
index 0000000..fb72864
--- /dev/null
+++ b/utils/persistent-policy.h
@@ -0,0 +1,125 @@
+/* -*-  Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * Copyright (c) 2011 University of California, Los Angeles
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation;
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ * Author: Alexander Afanasyev <alexander.afanasyev@ucla.edu>
+ */
+
+#ifndef PERSISTENT_POLICY_H_
+#define PERSISTENT_POLICY_H_
+
+#include <boost/intrusive/options.hpp>
+#include <boost/intrusive/list.hpp>
+
+namespace ndnSIM
+{
+
+/**
+ * @brief Traits for persistent replacement policy
+ *
+ * In this policy entries are added until there is a space (controlled by set_max_size call).
+ * If maximum is reached, new entries will not be added and nothing will be removed from the container
+ */
+struct persistent_policy_traits
+{
+  struct policy_hook_type : public boost::intrusive::list_member_hook<> {};
+
+  template<class Container>
+  struct container_hook
+  {
+    typedef boost::intrusive::member_hook< Container,
+                                           policy_hook_type,
+                                           &Container::policy_hook_ > type;
+  };
+
+  template<class Base,
+           class Container,
+           class Hook>
+  struct policy 
+  {
+    typedef typename boost::intrusive::list< Container, Hook > policy_container;
+    
+    // could be just typedef
+    class type : public policy_container
+    {
+    public:
+      typedef Container parent_trie;
+    
+      type (Base &base)
+        : base_ (base)
+        , max_size_ (100) // when 0, policy is not enforced
+      {
+      }
+
+      inline void
+      update (typename parent_trie::iterator item)
+      {
+        // do nothing
+      }
+  
+      inline bool
+      insert (typename parent_trie::iterator item)
+      {
+        if (max_size_ != 0 && policy_container::size () >= max_size_)
+          return false;
+      
+        policy_container::push_back (*item);
+        return true;
+      }
+  
+      inline void
+      lookup (typename parent_trie::iterator item)
+      {
+        // do nothing
+      }
+  
+      inline void
+      erase (typename parent_trie::iterator item)
+      {
+        policy_container::erase (policy_container::s_iterator_to (*item));
+      }
+
+      inline void
+      clear ()
+      {
+        policy_container::clear ();
+      }
+
+      inline void
+      set_max_size (size_t max_size)
+      {
+        max_size_ = max_size;
+      }
+
+      inline size_t
+      get_max_size () const
+      {
+        return max_size_;
+      }
+
+    private:
+      // type () : base_(*((Base*)0)) { };
+
+    private:
+      Base &base_;
+      size_t max_size_;
+    };
+  };
+};
+
+} // ndnSIM
+
+#endif // PERSISTENT_POLICY_H_
diff --git a/utils/random-policy.h b/utils/random-policy.h
index 7a96712..288cd74 100644
--- a/utils/random-policy.h
+++ b/utils/random-policy.h
@@ -29,6 +29,9 @@
 namespace ndnSIM
 {
 
+/**
+ * @brief Traits for random replacement policy
+ */
 struct random_policy_traits
 {
   struct policy_hook_type : public boost::intrusive::set_member_hook<> { uint32_t randomOrder; };
diff --git a/utils/trie-with-policy.h b/utils/trie-with-policy.h
index a2be29a..ea194b3 100644
--- a/utils/trie-with-policy.h
+++ b/utils/trie-with-policy.h
@@ -34,7 +34,6 @@
 {
 public:
   typedef trie< FullKey,
-                typename PayloadTraits::payload_type,
                 PayloadTraits,
                 typename PolicyTraits::policy_hook_type > parent_trie;
 
@@ -133,6 +132,16 @@
     return foundItem;
   }
 
+  // /**
+  //  * @brief Const version of the longest common prefix match
+  //  * (semi-const, because there could be update of the policy anyways)
+  //  */
+  // inline const_iterator
+  // longest_prefix_match (const FullKey &key) const
+  // {
+  //   return static_cast<trie_with_policy*> (this)->longest_prefix_match (key);
+  // }
+
   /**
    * @brief Find a node that has prefix at least as the key (cache lookup)
    */
@@ -221,7 +230,7 @@
   
 private:
   parent_trie      trie_;
-  policy_container policy_;
+  mutable policy_container policy_;
 };
 
 } // ndnSIM
diff --git a/utils/trie.h b/utils/trie.h
index 1b2056e..50288af 100644
--- a/utils/trie.h
+++ b/utils/trie.h
@@ -71,24 +71,23 @@
 // forward declarations
 //
 template<typename FullKey,
-         typename Payload,
          typename PayloadTraits,
          typename PolicyHook >
 class trie; 
 
-template<typename FullKey, typename Payload, typename PayloadTraits, typename PolicyHook>
+template<typename FullKey, typename PayloadTraits, typename PolicyHook>
 inline std::ostream&
 operator << (std::ostream &os,
-             const trie<FullKey, Payload, PayloadTraits, PolicyHook> &trie_node);
+             const trie<FullKey, PayloadTraits, PolicyHook> &trie_node);
 
-template<typename FullKey, typename Payload, typename PayloadTraits, typename PolicyHook>
+template<typename FullKey, typename PayloadTraits, typename PolicyHook>
 bool
-operator== (const trie<FullKey, Payload, PayloadTraits, PolicyHook> &a,
-            const trie<FullKey, Payload, PayloadTraits, PolicyHook> &b);
+operator== (const trie<FullKey, PayloadTraits, PolicyHook> &a,
+            const trie<FullKey, PayloadTraits, PolicyHook> &b);
 
-template<typename FullKey, typename Payload, typename PayloadTraits, typename PolicyHook >
+template<typename FullKey, typename PayloadTraits, typename PolicyHook >
 std::size_t
-hash_value (const trie<FullKey, Payload, PayloadTraits, PolicyHook> &trie_node);
+hash_value (const trie<FullKey, PayloadTraits, PolicyHook> &trie_node);
 
 ///////////////////////////////////////////////////
 // actual definition
@@ -97,7 +96,7 @@
 class trie_iterator;
 
 template<typename FullKey,
-	 typename Payload, typename PayloadTraits,
+	 typename PayloadTraits,
          typename PolicyHook >
 class trie
 {
@@ -109,6 +108,8 @@
 
   typedef trie_iterator<trie> recursive_iterator;
   typedef trie_iterator<const trie> const_recursive_iterator;
+
+  typedef PayloadTraits payload_traits;
   
   inline
   trie (const Key &key, size_t bucketSize = 10, size_t bucketIncrement = 10)
@@ -155,11 +156,11 @@
   
   // actual entry
   friend bool
-  operator== <> (const trie<FullKey, Payload, PayloadTraits, PolicyHook> &a,
-                 const trie<FullKey, Payload, PayloadTraits, PolicyHook> &b);
+  operator== <> (const trie<FullKey, PayloadTraits, PolicyHook> &a,
+                 const trie<FullKey, PayloadTraits, PolicyHook> &b);
 
   friend std::size_t
-  hash_value <> (const trie<FullKey, Payload, PayloadTraits, PolicyHook> &trie_node);
+  hash_value <> (const trie<FullKey, PayloadTraits, PolicyHook> &trie_node);
 
   inline std::pair<iterator, bool>
   insert (const FullKey &key,
@@ -231,11 +232,11 @@
     return this;
   }
 
-  inline boost::tuple<const iterator, bool, const iterator>
-  find (const FullKey &key) const
-  {
-    return const_cast<trie*> (this)->find (key);
-  }
+  // inline boost::tuple<const iterator, bool, const iterator>
+  // find (const FullKey &key) const
+  // {
+  //   return const_cast<trie*> (this)->find (key);
+  // }
 
   /**
    * @brief Perform the longest prefix match
@@ -280,7 +281,7 @@
     if (payload_ != PayloadTraits::empty_payload)
       return this;
 
-    typedef trie<FullKey, Payload, PayloadTraits, PolicyHook> trie;
+    typedef trie<FullKey, PayloadTraits, PolicyHook> trie;
     for (typename trie::unordered_set::iterator subnode = children_.begin ();
          subnode != children_.end ();
          subnode++ )
@@ -300,13 +301,13 @@
    * @returns end() or a valid iterator pointing to the trie leaf (order is not defined, enumeration )
    */
   template<class Predicate>
-  inline iterator
+  inline const iterator
   find_if (Predicate pred)
   {
     if (payload_ != PayloadTraits::empty_payload && pred (payload_))
       return this;
 
-    typedef trie<FullKey, Payload, PayloadTraits, PolicyHook> trie;
+    typedef trie<FullKey, PayloadTraits, PolicyHook> trie;
     for (typename trie::unordered_set::iterator subnode = children_.begin ();
          subnode != children_.end ();
          subnode++ )
@@ -414,12 +415,12 @@
 
 
 
-template<typename FullKey, typename Payload, typename PayloadTraits, typename PolicyHook>
+template<typename FullKey, typename PayloadTraits, typename PolicyHook>
 inline std::ostream&
-operator << (std::ostream &os, const trie<FullKey, Payload, PayloadTraits, PolicyHook> &trie_node)
+operator << (std::ostream &os, const trie<FullKey, PayloadTraits, PolicyHook> &trie_node)
 {
   os << "# " << trie_node.key_ << ((trie_node.payload_ != 0)?"*":"") << std::endl;
-  typedef trie<FullKey, Payload, PayloadTraits, PolicyHook> trie;
+  typedef trie<FullKey, PayloadTraits, PolicyHook> trie;
 
   for (typename trie::unordered_set::const_iterator subnode = trie_node.children_.begin ();
        subnode != trie_node.children_.end ();
@@ -436,9 +437,9 @@
   return os;
 }
 
-template<typename FullKey, typename Payload, typename PayloadTraits, typename PolicyHook>
+template<typename FullKey, typename PayloadTraits, typename PolicyHook>
 inline void
-trie<FullKey, Payload, PayloadTraits, PolicyHook>
+trie<FullKey, PayloadTraits, PolicyHook>
 ::PrintStat (std::ostream &os) const
 {
   os << "# " << key_ << ((payload_ != 0)?"*":"") << ": " << children_.size() << " children" << std::endl;
@@ -450,7 +451,7 @@
     }
   os << "\n";
 
-  typedef trie<FullKey, Payload, PayloadTraits, PolicyHook> trie;
+  typedef trie<FullKey, PayloadTraits, PolicyHook> trie;
   for (typename trie::unordered_set::const_iterator subnode = children_.begin ();
        subnode != children_.end ();
        subnode++ )
@@ -461,17 +462,17 @@
 }
 
 
-template<typename FullKey, typename Payload, typename PayloadTraits, typename PolicyHook>
+template<typename FullKey, typename PayloadTraits, typename PolicyHook>
 inline bool
-operator == (const trie<FullKey, Payload, PayloadTraits, PolicyHook> &a,
-             const trie<FullKey, Payload, PayloadTraits, PolicyHook> &b)
+operator == (const trie<FullKey, PayloadTraits, PolicyHook> &a,
+             const trie<FullKey, PayloadTraits, PolicyHook> &b)
 {
   return a.key_ == b.key_;
 }
 
-template<typename FullKey, typename Payload, typename PayloadTraits, typename PolicyHook>
+template<typename FullKey, typename PayloadTraits, typename PolicyHook>
 inline std::size_t
-hash_value (const trie<FullKey, Payload, PayloadTraits, PolicyHook> &trie_node)
+hash_value (const trie<FullKey, PayloadTraits, PolicyHook> &trie_node)
 {
   return boost::hash_value (trie_node.key_);
 }