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4.2. Wireless 3GPP Network Architecture

4.2. Wireless 3GPP Network Architecture​

The CLAT function on the User Equipment (UE) provides an [RFC1918] address and IPv4 default route to the local node's network stack. The applications on the UE can use the private IPv4 address for reaching global IPv4 hosts via translation on both the CLAT and the PLAT. On the other hand, reaching IPv6 hosts (including hosts presented via DNS64 [RFC6147]) does not require the CLAT function on the UE.

Presenting a private IPv4 network for tethering via NAT44 and stateless translation on the UE is also an application of the CLAT.

                              +------+
                              |  v6  |
                              | host |
                              +--+---+
                                 |
                             .---+---.
                            /         \
                           /   IPv6    \
                          |   Internet  |
                           \           /
  UE / Mobile Phone         `---------'
+----------------------+          |
| +----+    |          |      .---+---.                   .------.
| | v6 +----+   +------+     /         \     +------+    /        \
| +----+    |   |      |    / IPv6 PDP  \    |      |   /   IPv4   \
|           +---+ CLAT +---+ Mobile Core +---+ PLAT +--+  Internet  |
|           |   |      |    \    GGSN   /    |      |   \          /
|           |   +------+     \         '     +------+    `----+---'
| +-----+   |          |      `-------'                       |
| | v4p +---+          |                                   +--+---+
| +-----+   |          |                                   | v4g  |
+----------------------+                                   | host |
                                                          +------+

       <- v4p -> XLAT <--------- v6 --------> XLAT <- v4g ->

 v6   : Global IPv6
 v4p  : Private IPv4
 v4g  : Global IPv4
 PDP  : Packet Data Protocol
 GGSN : Gateway GPRS Support Node

Figure 2: Wireless 3GPP Network Topology

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