diff --git a/model/ccnx-l3-protocol.cc b/model/ccnx-l3-protocol.cc
index 4b832a4..d045339 100644
--- a/model/ccnx-l3-protocol.cc
+++ b/model/ccnx-l3-protocol.cc
@@ -38,6 +38,8 @@
 #include "ccnx-interest-header.h"
 #include "ccnx-content-object-header.h"
 
+#include "ccnx-net-device-face.h"
+
 #include <boost/foreach.hpp>
 
 NS_LOG_COMPONENT_DEFINE ("CcnxL3Protocol");
@@ -184,6 +186,20 @@
   return 0;
 }
 
+Ptr<CcnxFace>
+CcnxL3Protocol::GetFaceByNetDevice (Ptr<NetDevice> netDevice) const
+{
+  BOOST_FOREACH (const Ptr<CcnxFace> &face, m_faces) // this function is not supposed to be called often, so linear search is fine
+    {
+      Ptr<CcnxNetDeviceFace> netDeviceFace = DynamicCast<CcnxNetDeviceFace> (face);
+      if (netDeviceFace == 0) continue;
+
+      if (netDeviceFace->GetNetDevice () == netDevice)
+        return face;
+    }
+  return 0;
+}
+
 uint32_t 
 CcnxL3Protocol::GetNFaces (void) const
 {