diff --git a/model/cs/custom-policies/probability-policy.h b/model/cs/custom-policies/probability-policy.h
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+/* -*-  Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * Copyright (c) 2012 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 PROBABILITY_POLICY_H_
+#define PROBABILITY_POLICY_H_
+
+#include <boost/intrusive/options.hpp>
+#include <boost/intrusive/list.hpp>
+
+#include <ns3/random-variable.h>
+
+namespace ns3 {
+namespace ndn {
+namespace ndnSIM {
+
+/**
+ * @brief Traits for freshness policy
+ */
+struct probability_policy_traits
+{
+  static std::string GetName () { return "ProbabilityImpl"; }
+
+  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;
+    
+    class type : public policy_container
+    {
+    public:
+      typedef policy policy_base; // to get access to get_freshness methods from outside
+      typedef Container parent_trie;
+
+      type (Base &base)
+        : base_ (base)
+        , max_size_ (100)
+        , probability_ (1.0)
+      {
+      }
+
+      inline void
+      update (typename parent_trie::iterator item)
+      {
+      }
+
+      inline bool
+      insert (typename parent_trie::iterator item)
+      {
+        if (ns3_rand_.GetValue () < probability_)
+          {
+            policy_container::push_back (*item);
+
+            // allow caching
+            return true;
+          }
+        else
+          {
+            // don't allow caching
+            return false;
+          }
+      }
+
+      inline void
+      lookup (typename parent_trie::iterator item)
+      {
+        // do nothing. it's random policy
+      }
+
+      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_;
+      }
+
+      inline void
+      set_probability (double probability)
+      {
+        probability_ = probability;
+      }
+
+      inline double
+      get_probability () const
+      {
+        return probability_;
+      }      
+
+    private:
+      type () : base_(*((Base*)0)) { };
+
+    private:
+      Base &base_;
+      size_t max_size_;
+      double probability_;
+      UniformVariable ns3_rand_;
+    };
+  };
+};
+
+} // ndnSIM
+} // ndn
+} // ns3
+
+#endif // PROBABILITY_POLICY_H