diff --git a/daemon/face/internal-transport.cpp b/daemon/face/internal-transport.cpp
index d9dc238..070a4b5 100644
--- a/daemon/face/internal-transport.cpp
+++ b/daemon/face/internal-transport.cpp
@@ -40,6 +40,7 @@
   this->setScope(scope);
   this->setPersistency(ndn::nfd::FACE_PERSISTENCY_PERMANENT);
   this->setLinkType(linkType);
+  this->setMtu(MTU_UNLIMITED);
 
   NFD_LOG_FACE_INFO("Creating transport");
 }
diff --git a/daemon/face/transport.cpp b/daemon/face/transport.cpp
index d6008f7..0c4f4ee 100644
--- a/daemon/face/transport.cpp
+++ b/daemon/face/transport.cpp
@@ -60,15 +60,13 @@
 Transport::Transport()
   : m_face(nullptr)
   , m_service(nullptr)
-  , m_scope(ndn::nfd::FACE_SCOPE_NON_LOCAL)
-  , m_persistency(ndn::nfd::FACE_PERSISTENCY_PERSISTENT)
-  , m_linkType(ndn::nfd::LINK_TYPE_POINT_TO_POINT)
-  , m_mtu(MTU_UNLIMITED)
+  , m_scope(ndn::nfd::FACE_SCOPE_NONE)
+  , m_persistency(ndn::nfd::FACE_PERSISTENCY_NONE)
+  , m_linkType(ndn::nfd::LINK_TYPE_NONE)
+  , m_mtu(MTU_INVALID)
   , m_state(TransportState::UP)
   , m_counters(nullptr)
 {
-  // warning: Subclass constructor must explicitly initialize all static properties
-  // using setters, and should not rely on the defaults here.
 }
 
 Transport::~Transport()
diff --git a/daemon/face/transport.hpp b/daemon/face/transport.hpp
index b7f1c30..55efe3b 100644
--- a/daemon/face/transport.hpp
+++ b/daemon/face/transport.hpp
@@ -55,6 +55,10 @@
  */
 const ssize_t MTU_UNLIMITED = -1;
 
+/** \brief (for internal use) indicates MTU field is unset
+ */
+const ssize_t MTU_INVALID = -2;
+
 /** \brief the lower part of an LpFace
  *  \sa LpFace
  */
@@ -89,6 +93,14 @@
     EndpointId remoteEndpoint;
   };
 
+  /** \brief constructor
+   *
+   *  Transport constructor initializes static properties to invalid values.
+   *  Subclass constructor must explicitly set every static property.
+   *
+   *  This constructor initializes TransportState to UP;
+   *  subclass constructor can rely on this default value.
+   */
   Transport();
 
   virtual