diff --git a/model/ndn-l3-protocol.cc b/model/ndn-l3-protocol.cc
index a32c7fa..86002e3 100644
--- a/model/ndn-l3-protocol.cc
+++ b/model/ndn-l3-protocol.cc
@@ -186,6 +186,13 @@
 Ptr<Face>
 L3Protocol::GetFace (uint32_t index) const
 {
+  NS_ASSERT (0 <= index && index < m_faces.size ());
+  return m_faces[index];
+}
+
+Ptr<Face>
+L3Protocol::GetFaceById (uint32_t index) const
+{
   BOOST_FOREACH (const Ptr<Face> &face, m_faces) // this function is not supposed to be called often, so linear search is fine
     {
       if (face->GetId () == index)
diff --git a/model/ndn-l3-protocol.h b/model/ndn-l3-protocol.h
index 372ac6a..25dfd39 100644
--- a/model/ndn-l3-protocol.h
+++ b/model/ndn-l3-protocol.h
@@ -67,6 +67,8 @@
     public Object
 {
 public:
+  typedef std::vector<Ptr<Face> > FaceList;
+
   /**
    * \brief Interface ID
    *
@@ -103,14 +105,22 @@
    */
   virtual uint32_t
   GetNFaces () const;
-  
+
   /**
    * \brief Get face by face index
-   * \param face The face number of an Ndn interface.
+   * \param face The face number (number in face list)
    * \returns The NdnFace associated with the Ndn face number.
    */
   virtual Ptr<Face>
   GetFace (uint32_t face) const;
+  
+  /**
+   * \brief Get face by face ID
+   * \param face The face ID number
+   * \returns The NdnFace associated with the Ndn face number.
+   */
+  virtual Ptr<Face>
+  GetFaceById (uint32_t face) const;
 
   /**
    * \brief Remove face from ndn stack (remove callbacks)
@@ -143,7 +153,6 @@
   
 private:
   uint32_t m_faceCounter; ///< \brief counter of faces. Increased every time a new face is added to the stack
-  typedef std::vector<Ptr<Face> > FaceList;
   FaceList m_faces; ///< \brief list of faces that belongs to ndn stack on this node
 
   // These objects are aggregated, but for optimization, get them here