diff --git a/model/ccnx-face.h b/model/ccnx-face.h
index 787bfa0..4370ab9 100644
--- a/model/ccnx-face.h
+++ b/model/ccnx-face.h
@@ -31,9 +31,10 @@
 class Packet;
 class Node;
 
+  
 /**
  * \ingroup ccnx
- * \defgroup ccnx-face
+ * \defgroup ccnx-face Faces
  */
 /**
  * \ingroup ccnx-face
@@ -54,7 +55,7 @@
    * \param face Face from which packet has been received
    * \param packet Received packet
    */
-  typedef Callback<void,const Ptr<CcnxFace>&,const Ptr<Packet>& > ProtocolHandler;
+  typedef Callback<void,const Ptr<CcnxFace>&,const Ptr<const Packet>& > ProtocolHandler;
   
   /**
    * \brief Interface ID
diff --git a/model/ccnx-l3-protocol.cc b/model/ccnx-l3-protocol.cc
index 07bf848..ff3f926 100644
--- a/model/ccnx-l3-protocol.cc
+++ b/model/ccnx-l3-protocol.cc
@@ -155,7 +155,7 @@
 
   m_faces.push_back (face);
   m_faceCounter ++;
-  return m_faceCounter;
+  return face->GetId ();
 }
 
 Ptr<CcnxFace>
@@ -177,7 +177,7 @@
 
 // Callback from lower layer
 void 
-CcnxL3Protocol::Receive (const Ptr<CcnxFace> &face, const Ptr<Packet> &p)
+CcnxL3Protocol::Receive (const Ptr<CcnxFace> &face, const Ptr<const Packet> &p)
 {
   NS_LOG_LOGIC ("Packet from face " << &face << " received on node " <<  m_node->GetId ());
 
diff --git a/model/ccnx-l3-protocol.h b/model/ccnx-l3-protocol.h
index 4743bdd..145051f 100644
--- a/model/ccnx-l3-protocol.h
+++ b/model/ccnx-l3-protocol.h
@@ -105,7 +105,7 @@
   Ptr<CcnxForwardingStrategy> GetForwardingStrategy () const;
 
   virtual void Send (const Ptr<CcnxFace> &face, const Ptr<Packet> &packet);
-  virtual void Receive (const Ptr<CcnxFace> &device, const Ptr<Packet> &p);
+  virtual void Receive (const Ptr<CcnxFace> &face, const Ptr<const Packet> &p);
 
   virtual uint32_t AddFace (const Ptr<CcnxFace> &face);
   virtual uint32_t GetNFaces () const;
@@ -113,7 +113,7 @@
 
 protected:
   /**
-   * Actual processing of incoming CCNx packets. Also processing packets coming from local apps
+   * \brief Actual processing of incoming CCNx interests
    * 
    * Processing Interest packets
    */
@@ -124,7 +124,7 @@
 
   
   /**
-   * Actual processing of incoming CCNx packets. Also processing packets coming from local apps
+   * \brief Actual processing of incoming CCNx content objects
    * 
    * Processing ContentObject packets
    */
@@ -153,12 +153,12 @@
   ReceiveAndProcess (Ptr<CcnxFace> face, Ptr<Header> header, Ptr<Packet> p);
 
 private:
-  uint32_t m_faceCounter; ///< counter of faces. Increased every time a new face is added to the stack
+  uint32_t m_faceCounter; ///< \brief counter of faces. Increased every time a new face is added to the stack
   typedef std::vector<Ptr<CcnxFace> > CcnxFaceList;
-  CcnxFaceList m_faces;
+  CcnxFaceList m_faces; ///< \brief list of faces that belongs to ccnx stack on this node
 
-  Ptr<Node> m_node;
-  Ptr<CcnxForwardingStrategy> m_forwardingStrategy;
+  Ptr<Node> m_node; ///< \brief node on which ccnx stack is installed
+  Ptr<CcnxForwardingStrategy> m_forwardingStrategy; ///< \brief smart pointer to the selected forwarding strategy
 
   // TracedCallback<Ptr<const Packet>, Ptr<const CcnxFace> > m_sendOutgoingTrace;
   // TracedCallback<Ptr<const Packet>, Ptr<const CcnxFace> > m_unicastForwardTrace;
diff --git a/model/ccnx-net-device-face.cc b/model/ccnx-net-device-face.cc
index 37a3555..b5816a4 100644
--- a/model/ccnx-net-device-face.cc
+++ b/model/ccnx-net-device-face.cc
@@ -44,14 +44,14 @@
 }
 
 /** 
- * By default, Ccnx face are created in the "down" state
- *  with no IP addresses.  Before becoming useable, the user must 
- * invoke SetUp on them once an Ccnx address and mask have been set.
+ * By default, Ccnx face are created in the "down" state.  Before
+ * becoming useable, the user must invoke SetUp on the face
  */
-CcnxNetDeviceFace::CcnxNetDeviceFace () 
-  : m_netDevice (0)
+CcnxNetDeviceFace::CcnxNetDeviceFace (const Ptr<NetDevice> &netDevice) 
 {
   NS_LOG_FUNCTION (this);
+
+  m_netDevice = netDevice;
 }
 
 CcnxNetDeviceFace::~CcnxNetDeviceFace ()
@@ -77,12 +77,6 @@
   Object::DoDispose ();
 }
 
-void 
-CcnxNetDeviceFace::SetNetDevice (Ptr<NetDevice> netDevice)
-{
-  m_netDevice = netDevice;
-}
-
 Ptr<NetDevice>
 CcnxNetDeviceFace::GetNetDevice () const
 {
@@ -127,7 +121,7 @@
                                          const Address &to,
                                          NetDevice::PacketType packetType)
 {
-  // bla bla bla
+  m_protocolHandler (Ptr<CcnxFace>(this), p);
 }
 
 
diff --git a/model/ccnx-net-device-face.h b/model/ccnx-net-device-face.h
index 397d6c1..baf6a48 100644
--- a/model/ccnx-net-device-face.h
+++ b/model/ccnx-net-device-face.h
@@ -36,6 +36,10 @@
  * component responsible for actual delivery of data packet to and
  * from CCNx stack
  *
+ * CcnxNetDevice face is permanently associated with one NetDevice
+ * object and this object cannot be changed for the lifetime of the
+ * face
+ *
  * \see CcnxLocalFace, CcnxNetDeviceFace, CcnxIpv4Face, CcnxUdpFace
  */
 class CcnxNetDeviceFace  : public CcnxFace
@@ -49,9 +53,12 @@
   static TypeId GetTypeId (void);
 
   /**
-   * \brief Default constructor
+   * \brief Constructor
+   *
+   * \param netDevice a smart pointer to NetDevice object to which
+   * this face will be associate
    */
-  CcnxNetDeviceFace ();
+  CcnxNetDeviceFace (const Ptr<NetDevice> &netDevice);
   virtual ~CcnxNetDeviceFace();
 
   ////////////////////////////////////////////////////////////////////
@@ -64,13 +71,6 @@
   ////////////////////////////////////////////////////////////////////
 
   /**
-   * \brief Associate NetDevice object with face
-   *
-   * \param node smart pointer to a NetDevice object
-   */
-  void SetNetDevice (Ptr<NetDevice> node);
-
-  /**
    * \brief Get NetDevice associated with the face
    *
    * \returns smart pointer to NetDevice associated with the face
@@ -84,7 +84,7 @@
   CcnxNetDeviceFace (const CcnxNetDeviceFace &); ///< \brief Disabled copy constructor
   CcnxNetDeviceFace& operator= (const CcnxNetDeviceFace &); ///< \brief Disabled copy operator
 
-  // callback
+  /// \brief callback from lower layers
   void ReceiveFromNetDevice (Ptr<NetDevice> device,
                              Ptr<const Packet> p,
                              uint16_t protocol,
diff --git a/model/ccnx.h b/model/ccnx.h
index 1cbe428..412fd2e 100644
--- a/model/ccnx.h
+++ b/model/ccnx.h
@@ -90,7 +90,7 @@
    * \param p the packet
    */
   virtual void
-  Receive (const Ptr<CcnxFace> &device, const Ptr<Packet> &p) = 0;
+  Receive (const Ptr<CcnxFace> &face, const Ptr<const Packet> &p) = 0;
 
   /**
    * \brief Register a new forwarding strategy to be used by this Ccnx