+-------------+
        Private +----------+ IPv4-in-IPv6|Stateful AFTR|
+------+  IPv4  |    B4    |    Tunnel   |------+------+     _______
| IPv4 |------->| Encap./  |------------>|Encap.|      |    ( IPv4  )
|Device|<-------|  Decap.  |<------------|  /   | NAPT +--( Internet )
+------+        +----------+      ^      |Decap.|  44  |   (________)
                                  |      +------+------+
                            Operator IPv6
                              Network