This MIB module manages the Quality of Service 
parameters of GGSN in a GPRS system.

GGSN is the Gateway GPRS Support Node in the GPRS
architecture. It provides interworking of GPRS 
network with external packet-switched networks 
- PDNs or other data networks.

The following diagram illustrates a simplified GPRS
logical architecture with the name of inter-node
interface:

+---------------------------------------------+
|                         +======+   a PLMN   |
|                         | SGSN |            |
|                         +======+            |
|                            |                |
|                            Gn               |
|                            |                |
|+====+   +====+ +=====+ +======+    +======+ |    +===+
|| TE |-R-| MT |-| BSS |-| SGSN |-Gn-| GGSN |-|-Gi-|PDN|
|+====+   +====+ +=====+ +======+    +======+ |    +===+
|                                        |    |
|                                        |    |
+----------------------------------------|----+
                                         Gp
                                         |
                +-----------------------------+
                | +====+   +=====+   +======+ |
                | | MS |---| BSS |---| SGSN | |
                | +====+   +=====+   +======+ |
                |                             |
                |                other PLMN   |
                +-----------------------------+

A PDP Context is an information set maintained by MS
and GSNs which describes the mobile wireless service
call or session.

Three types of QoS mapping method are supported on GGSN:
canonical, delay and UMTS. Canonical QoS mapping 
consists of Best Effort, Normal and Premium QoS classes.
Delay QoS mapping consists of four classes: delay1, 
delay2, delay3 and delay-besteffort. UMTS QoS has the 
following traffic classes: signalling, conversational, 
streaming, interactive and background. UMTS QoS is 
based on differentiated services network model.

A QoS Profile is associated with each PDP context which
defines multiple attributes like precedence, delay,
reliability, peak throughput, mean throughput and 
traffic class.  Based on the precedence, delay and mean
throughput an user is classified into different 
canonical and delay QoS classes .  Based on delay, 
jitter, bandwidth and reliability user is classified 
into the UMTS traffic classes.

In GGSN, the QoS remapping mechanism is that, for 
uplink traffic, the GGSN remaps the TOS in the user 
traffic before forwarding the packet to the Gi 
interface and for downlink traffic, the GGSN will 
only setup the TOS for the IP header for the Tunnel, 
not the IP header for user traffic. Traffic from MS 
to PDN is considered as uplink and the reverse is 
considered as downlink traffic.

Acronyms and terms:

APN      Access Point Name
BSS      Base Station System
ETSI     European Telecommunications Standards
         Institute
DS       Differentiated Service 
DSCP     DS Code Point
GGSN     Gateway GPRS Support Node
GPRS     General Packet Radio Service
GSM      Global System for Mobile communication
GSN      GPRS Support Node
G-PDU    GTP PDU
MS       Mobile Station
MT       Mobile Terminal
PDN      Packet Data Network
PDP      Packet Data Protocol
PDU      Protocol Data Unit
PHB      Per-hop Behavior
PLMN     Public Land Mobile Network
SGSN     Serving GPRS support Node
TE       Terminal Equipment
T-PDU    the payload of G-PDU
UMTS     Universal Mobile Telecommunication System
IMS      IP Multimedia Subsystem
GBR      Guaranteed Bit Rate
MBR      Maximum Bit Rate
CAC      Call Admission Control
QOS      Quality Of Service

REFERENCE

[1] GSM 03.60: Digital cellular telecommunications
    system (Phase 2+); General Packet Radio Service
    (GPRS); Service description; Stage 2. V7.1.0

[2] GSM 09.60: Digital cellular telecommunication
    system (Phase 2+); General Packet Radio Service
    (GPRS); GPRS Tunnelling Protocol (GTP) across
    Gn and Gp Interface. V7.3.0

[3] 3GPP; Technical Specification Group Services
    and System Aspects; QoS Concept and Architecture.
    3G TS 23.107 v3.2.0.

[4] 3GPP; Technical Specification Group Core Network;
    General Packet Radio Service(GPRS); GPRS 
    Tunnelling Protocol (GTP) across Gn and Gp 
    Interface (Release 1999). 3G TS 29.060 v3.5.0.

[5] 3GPP; Technical Specification Group Services
    and System Aspects; General Packet Radio 
    Service(GPRS); Service description; Stage 2 
    (Release 1999) 3G TS 23.060 v3.3.1.