This MIB module manages the GPRS Tunneling Protocol
version 2(GTPv2) statistics for the Evolved Packet
Core(EPC) architecture.
        
SGW and PGW are the key elements of EPC architecture.
        
The PGW is the permanent IP point-of-attachment for 
access via the E-UTRAN. The PGW performs IP policy and
charging enforcement on packet flows to and from mobile 
devices.
        
The SGW is a local mobility anchor for E-UTRAN mobility,
switching packets between the S5 interface and the GTP
based S1-U interface for mobiles in connected mode.
        
The following diagram illustrates the EPC logical
architecture with the name of inter-node interface:        
        
+------------------------------------------------+  
|                                                |
|                                                |
|           +=======+__________                  |
|           | UTRAN |          |S12              | 
|           |      +======+    |                 | 
|           +======|      |    |                 |
|           +======| SGSN |___ |                 |
|           |      +======+   ||                 |
|           | GERAN |  |    S4||                 |
|           +=======+  |(GTP-C||                 |
|                    S3| VO,V1||                 |
|                      |  GTPU||                 |   
|                      |VO,V1)||                 |
|                  +======+   ||                 | 
|              ____| MME  |__ ||                 |
|              |   +======+  |||                 |
|        S1-MME|      S11    |||                 |
|              |     GTP-C   |||                 |
|              |  (V0,V1,V2) |||                 |
|+====+ +========+        +======+     +======+  |  +===+
|| UE |-|E-Utran |        | SGW  |     | PGW  |-SGi-|PDN|
||    | |(EnodeB)|        |      |     |      |  |  |   |
|+====+ +========+        +======+     +======+  |  +===+
|              |            |  |  GTP-C   |      | 
|              |            |  |(vo,v1,v2)|      | 
|              |            |  |GTP-C     |      |  
|              |            |  |  (vo,v1) |      | 
|              |  GTP v2-u  |  |          |      |
|               ------------   -----------       |
|                  (S1-U)          S5            |
|                                                |
+------------------------------------------------+
        
GTP is the protocol between SGW and PGW in the EPC
backbone network. It includes both the GTP signaling
and data transfer procedures.
        
The GTP signaling provides control and support for
the user data and is know as control plane messages.
Where as the user data is known as user plane messages.
        
SGW and PGW supports GTPv2, GTPv1 and GTPv0
simultaneously. 
        
GTPv2 has been introduced in this evolution. It is
different from GTPv1 and GTPv0 in few respects, for E-UTRAN
access to EPC, the PDN connectivity service is provided
by EPS bearer. An EPS bearer uniquely identifies traffic
flows between an UE and EPC.
        
Acronyms and terms:
        
 3GPP   3rd Generation Partnership Project
 EPC    Evolved Packet Core
 EPS    Evolved Packet System
 E-UTRAN Evolved UTRAN
 GPRS   General Packet Radio Service
 GTP    GPRS Tunneling Protocol
 PDN    Public Data Network
 PGW    PDN Gateway
 SGW    Serving Gateway
 UE     User Equipment
 UMTS   Universal Mobile Telecommunications System
 UTRAN  UMTS Radio Access Network
        
        
REFERENCE
        
[1] 3GPP: Evolved GPRS Tunneling Protocol for Control
    Plane (GTPv2-C). 3GPP TS 29.274 V1.3.1
        
[2] 3GPP: GPRS enhancements for EUTRAN access.
    3GPP TS 23.401 V8.3.0