Transcript GGSN

行動通訊簡訊及多媒體訊息
溫志宏 博士
吳承崧 博士
蘇暉凱 博士
國立中正大學電信研究中心
Outlines
 課程內容：
 GSM Introduction (3 hrs)
 GPRS Introduction (3 hrs)
 SMS & EMS (3 hrs) (Ref: 3GPP TS 23.040_MMS.pdf)
 MMS (9 hrs) (Ref: 3GPP TS 23.140_MMSFD.pdf)
 MMS Application (Java 2 Micro Edition) Programming (9 hrs)
 實習：
 MMS Application (Java 2 Micro Edition) Programming (9 hrs)
GPRS network
Logical network elements
BS
S
GPRS
Core
network
Extern
al
packet
networ
ks
Value
added
service
s
(WAP)
GPRS network
Logical network elements
BTS
NMS
BSC
Billing SGSN
Center GGSN
SGSN
CG
NMS
BG
CG
FW
LIG
= Serving GPRS Support Node
= Gateway GPRS Support Node
= Network Management System
= Border Gateway
= Charging Gateway
= Firewall
= Lawful Interception Gateway
FW
GPRS
Backbone
GGSN
BG
Internet
Intranet
GGSN
LIG
GGSN
DNS
Router
Server
LAN
FW
InterPLMN
Network
Corporate
Operator
Services
LAN
SGSN & GGSN
functionalities
HLR
BTS
MSC/
VLR
BSC
GGSN
SS7
SGSN
• GTP tunneling to SGSN
• Interfaces to external IP
networks
• Charging & statistics
• NMS interfaces
SGSN
• Authentication
• GTP tunneling to GGSN
• Ciphering & compression
• Mobility management
• Interaction with HLR,
MSC/VLR
• Charging & statistics
• NMS interfaces
GPRS
Backbone
IP Network
GGSN
Internet
FW
Serving GPRS Support Node
(SGSN)
Functions……….
• Mobility management
• Authentication
• Ciphering & compression
• Protocol conversion
• GTP tunneling to GGSN
• Interaction with HLR, MSC/VLR
• Charging & statistics
• NMS interfaces
Gateway GPRS Support Node
(GGSN)
Functions……….
• Essentially a router
• Interfaces to external IP networks
• GTP tunneling to SGSN
• Charging & statistics
• NMS interfaces
Border Gateway (BG)
Functions……….
• Essentially a router similar to GGSN
• Provides a secure 'tunnel' for
transferring data on the inter-PLMN
backbone between different
operators
• Supports protocols like BGP-4
Domain Name Server (DNS)
Functions……….
• Standard IP device
• Converts domain names into IP addresses
• Based on a hierarchical & distributed
model
Firewall (FW)
Functions……….
• Standard IP device
• Protects against unauthorized access
(hackers)
Charging Gateway (CG)
Functions……….
• Collects charging data from SGSN & GGSN
• Processes the charging data & forwards it
to the Billing System
Lawful Interception Gateway
(LIG)
Functions……….
• Intercepts user data, MM information,
subscriber information etc.
• Forwards it to Law Enforcement Agency (LEA)
GPRS Interfaces
MSC/
VLR
HLR
Signalling and data
SMSGMSC
EIR
Signalling
Gr
Gs
Ga
SGSN
BSC
Gb
CG
Gd
Gf
Gc
G
a
Gi
Gn
External
packet
network
GGSN
Abis
Air (Um)
Gn
BG
Gp
Inter-PLMN
GPRS
Backbone
GGSN functionalities
HLR
BTS
MSC/
VLR
BSC
SS7
SGSN
GPRS
Core
Network
GGSN
Internet
Server
Application Layer
USER
PAYLOAD
GTP
GPRS
Backbone
Layers 1 & 2
UDP
IP
L2
L1
Tunnelled
payload
APP
TCP/UDP
IP
L2
GPRS tunnel L1
Transport layer
Network layer
Transport layer
Network layer
Public
Data Network
Layers 1 & 2
GPRS architecture key points (1)
The Gateway GPRS Support Node (GGSN):
– acts as the interface between the GPRS network and external
networks
– collects charging data and traffic statistics
– can allocate IP-addresses for users
– routes packets coming from external networks towards the
correct SGSN and vice versa
Serving GPRS Support Node (SGSN):
– converts protocols used in the IP backbone to protocols used in
the BSS and the MS
– takes care of authentication and mobility management
– routes data to the relevant GGSN when connection to an
external network is required
– collects charging data and traffic statistics.
Mobility Management States
– The tracking of the location of an MS depends on the
mobility management state. GPRS has three mobility
management states.
•
IDLE
•
READY
•
STANDBY
– Each state describes a certain level of functionality &
information allocated.
– The change between the states happens upon activity or
when a timer expires.
Mobility Management States
• Idle State
– Subscriber is not attached to the GPRS network
– No valid MM context of the subscriber e.g. MS
switched off
HLR
IMSI 244...
VLR-1
BSC
IMSI
LAI
SGSN ?
SGSN-1
RA-1
LA-1
VLR
IMSI
RA
Cell
?
?
?
Mobility Management States
• Ready State
– After successful GPRS Attach
– Location tracked to the cell level
– Activation & deactivation of PDP context possible
– Sending and receiving of SMS is possible
– MS can receive paging for circuit switched services
(optional)
– Data can not be transferred until a PDP context is
activated. After the PDP context activation, the SGSN
can send data to the MS without paging at any time.
– Ready timer expiry moves MS to the STANDBY state
Mobility Management States
• Standby State
– Subscriber is attached to the MM context
– Location tracked at RA level
– If SGSN receives a packet for the MS, it pages in the
RA. A PDP context must be active.
– Activation of PDP context possible. If the MS sends
data, it moves to the ready state.
– MS can receive paging for CS services (optional)
– The MS Reachable Timer starts ticking when the MS
enters the Standby state & the MS is detached (IDLE
state) upon its expiry (Implicit detach).
Mobility Management - GPRS
Attach (1)
HLR
SGSN-1
2a
2b
1
BSC
RA-1
LA-1
(1) MS requests GPRS attach
(2a) The MS is not known in the PLMN so the SGSN requests
subscriber identity (first time)
(2b) The MS sends its IMSI.
GPRS Attach (2) -Authentication
3b
HLR
3a
SGSN-1
3c
3d
BSC
RA-1
LA-1
(3a) SGSN requests triplets from HLR
(3b) The AC generates the triplets and hands them to the SGSN
(3c) The SGSN sends an Authentication Request to the MS
(3d) MS sends back the Authentication Response
The SGSN performs the authentication
GPRS Attach (3) - IMEI check
4d
EIR
4c
SGSN-1
4a
4b
BSC
RA-1
LA-1
(4a) SGSN asks for the MS IMEI
(4b) MS sends the IMEI
(4c) SGSN sends a Check IMEI message to the EIR
(4d) EIR replies with a Check IMEI ack that will include the list type
Mobility Management - GPRS Attach (4)
HLR
5d
5b
5a
SGSN-1
5c
6a
BSC
6b
RA-1
LA-1
(5a) SGSN sends an Update location message to the HLR with the IMSI
(5b) The HLR responds by giving subscriber data to the SGSN
(5c) The SGSN acknowledges that it has received the subscriber data ok
(5d) The HLR ends the transaction with an Update Location acknowledge
(6a) The SGSN accepts the GPRS attach and sends the MS a new P-TMSI
(6b) The MS acknowledges that it has received the new P-TMSI
Session Management - PDP Context
Activation
Process of assigning an IP address for becoming a part of the IP network
• One or more addresses can be assigned to an IMSI (MS).
• Contains mapping and routing information for transferring
PDUs between MS and GGSN.
• Information includes: IP address, Access Point Name,
QoS, Radio Priority, NSAPI, and LLC SAPI.
• Static addresses: address allocated by operator to an MS
permanently and this address is stored in the HLR.
• Dynamic addresses: GGSN dynamically allocates and
releases addresses as PDP contexts are activated and
deactivated.
PDP context activation
Overview
SGSN
3b
GGSN
3a
BSC
RA-1
LA-1
4
2
1. Activate PDP context request
1
2. Auth. /IMEI check (optional)
3a. Create PDP context request
3b. Create PDP context response
4. Activate PDP context accept
PDP Context Activation - 1
1. MS sends "Activate PDP
Context Request" to
SGSN
HLR
2
BSC
BTS
SS7
1
APN=
"Intranet.Ltd.com"
– Access Point Name
– PDP Type (IP)
– PDP Address (empty =
dynamic)
– QoS & other options
SGSN
DNS
GPRS
Core
Network
Access
Point
Intranet
GGSN
Internet
2. SGSN checks Subscription data
Access Point Name
Dynamic / static IP address
PDP Context Activation - 2:
Finding the GGSN
3. SGSN gets the GGSN IP address from
DNS
APN maps to the GGSN IP address
BTS
BSC
SGSN
3
4
GPRS
Core
Network
4. SGSN sends "Create PDP Context Request"
to GGSN
PDP Type (e.g. IP)
PDP Address (if empty=> dynamic address)
Access Point Name
DNS
QoS & other options
Access
Point
Intranet
GGSN
Internet
PDP Context Activation - 3
Access Point Selection
BTS
BSC
SGSN
• Access Point Name refers to
the external network the
subscriber wants to use
– Physical/logical interface in
GGSN
• Access Point configuration in
GGSN defines where to
connect the user
DNS
APN=
"Intranet.Ltd.com"
GPRS
Core
Network
Intranet
GGSN
Internet
PDP Context Deactivation
•The MS or the network can deactivate a PDP context.
•Every address can be deactivated separately, but performing a
GPRS Detach will automatically remove all the PDP contexts.
SMS data transfer
a) MSC address
b) SGSN address
2)
HLR
3a)
MSC
1) SMS
3b)
SGSN
G-MSC
SMSC
2). Send routing info. for Short Message
(GMSC-HLR)
Send routing info. for Short Message result
(HLR-GMSC)
PDP Context Activation - 4
Context Activated
BTS
• User authenticated OK (nontransparent case)
• User dynamic IP address allocated
by RADIUS server, or DHCP server,
or GGSN internal pool
5. GGSN sends "Create PDP Context
Response" back to SGSN
BSC
6. SGSN sends "Activate PDP Context Accept"
to the MS
6
SGSN
GPRS
Core
Network
• SGSN now ready to route user traffic between
MS and GGSN
GGSN
Intranet
5
Internet
GPRS Attach v/s PDP Context
Activation
• GPRS Attach
– MOBILITY MANAGEMENT PROCEDURE
– Establishes a logical link between the MS and the
SGSN.
– Makes the MS available for SMS over GPRS, paging
via SGSN, and notification of incoming GPRS data.
– Transmission of user data is not possible
• PDP Context Activation
– IP address is assigned to the MS.
– Makes the MS known in the corresponding GGSN.
– SESSION MANAGEMENT PROCEDURE
Context Activation for a Roaming User (0)
Visited Operator
DNS
.GPRS
DNS
SGSN
BG
Inter-PLMN
GPRS
Backbone
DNS
HOME
BG
HOME
Operator
GPRS
GGSN
Context Activation for a Roaming User (1)
Visited Operator, Singapore
DNS
2
3
Singapore
GPRS
SGSN Backbone
.GPRS
DNS
BG
Inter-PLMN
GPRS
Backbone
1
DNS
HOME
BG
HOME
Operator
GPRS
GGSN
GSM OPERATOR, Finland
Embassy
Intranet
Context Activation for a Roaming User (2)
Visited Operator, Singapore
DNS
Singapore
GPRS
SGSN Backbone
5
BG
DNS
HOME
BG
HOME
Operator
GPRS
.GPRS
DNS
4
Inter-PLMN
GPRS
Backbone
GGSN
GSMOPERATOR, Finland
Embassy
Intranet
Context Activation for a Roaming User (3)
Visited Operator, Singapore
DNS
Singapore
GPRS
SGSN Backbone
BG
7
6
DNS
HOME
.GPRS
DNS
BG
HOME
Operator
GPRS
Inter-PLMN
GPRS
Backbone
GGSN
GSMOPERATOR, Finland
Embassy
Intranet
Context Activation for a Roaming User (4)
Visited Operator, Singapore
DNS
8
Singapore
GPRS
SGSN Backbone
.GPRS
DNS
BG
9
DNS
HOME
BG
HOME
Operator
GPRS
Inter-PLMN
GPRS
Backbone
GGSN
GSMOPERATOR, Finland
Embassy
Intranet
The Data Flow in a Roaming Case
Visited Operator, Singapore
Singapore
GPRS
SGSN Backbone
BG
Inter-PLMN
Backbone
BG
HOME
Operator
GPRS
GGSN
GSMOPERATOR, Finland
Embassy
Intranet
Connection options
SGSN
Gp
Singapore
GPRS
Backbone
BG
GGSN
Internet
Inter-PLMN
Backbone
Gp
Gi
BG
HOME
Operator
GPRS
GGSN
Gi
Embassy
Intranet
Roaming, Dynamic IP-address from Home
Network, APN Always the Same
Visited Operator
SGSN
Visited-PLMN
GPRS
Backbone
GGSN
BG
Inter-PLMN
GPRS
Backbone
IP address changes
BG
HOME
Operator
GPRS
GGSN
Internet/
Intranet
Access Point
Roaming, Dynamic IP-address from
a Visited Network
Visited Operator
SGSN
Visited-PLMN
GPRS
Backbone
GGSN
Access Point
BG
Inter-PLMN
GPRS
Backbone
x.x.x.x
Internet
BG
HOME
Operator
GPRS
GGSN
Charging of GPRS services
GTP'
Charging gateway
Nokia GPRS Charging
Gateway:
SGSN
Operator
IP backbone
Border Gateway
Inter operator
IP network
Billing System
GTP'
GGSN
Internet
* receives CDRs generated by
SGSN and GGSN
•consolidates and merges
CDRs to a suitable format for
BS
GGSN Charging Functions
CG
SGSN
Operator
IP backbone
G-CDRs
GGSN
Internet
GGSN CDR (PDP context data) : G-CDR
Start collection:
- PDP context activation
Stop collection:
- PDP context deactivation
Collected information e.g.
- Traffic volumes
uplink/downlink
- QoS negotiated
- Duration
- SGSN & GGSN address
- Access Point Name
SGSN Charging Functions
S-CDRs
M-CDRs
SMSCDRs
CG
SGSN
Operator
IP backbone
GGSN
Internet
SGSN CDR (PDP context data) : S-CDR
Start collection:
- PDP context activation
Stop collection:
- PDP context deactivation
Collected information e.g.
- Traffic volumes uplink/downlink
- QoS requested/negotiated
- Duration
- SGSN & GGSN address
- Access Point Name
Mobility Management CDR : M-CDR
Start collection:
- GPRS activation / Incoming SGSN RA
update
Stop collection:
- GPRS deactivation / Outgoing SGSN RA
update
Collected information
- Location changes
CG Functionality
Main tasks of CG are:
• CDR collection from GSNs (CG receives the CDRs
with GTP')
• intermediate storage for CDRs
• CDR validation
• CDR consolidation
• CDR formatting
• adaptation to different CCB System interfaces
• to reduce the CDR processing load of the CCB System
GPRS Charging introduces new billing
concepts
GSM
traffic
GPRS
traffic
Rating
based on:
Dialled digits
Access Point Name
IP Address Allocation
Usage
based on:
Call duration
SMS transaction
Data Volume
Context duration
SMS transaction
Intermediate
records:
Not needed
Necessary
Roaming case 1
Visitor
CLEARING
CCB
CCB
CG
CG
SGSN
HOME
NETWORK
SGSN
Operator B
IP backbone
Operator A
IP backbone
Border Gateway
GGSN
APN
GGSN
APN
Internet
VISITING
NETWORK
Roaming case 2
Visitor
CLEARING
CCB
SGSN
HOME
NETWORK
CCB
CG
CG
SGSN
Operator B
IP backbone
Operator A
IP backbone
Border Gateway
GGSN
APN
GGSN
APN
Internet
VISITING
NETWORK
APN (Access Point Name)
•APN=Network ID+Operator ID
Example:
internet201.kgt.com,tw.mnc088.mcc466.gprs
•Selection Mode
*SentByMS: MS-provided APN, subscription not verified.
*Subscribed: MS or Network-provided APN, subscription verified.
*ChosenBySGSN: Network-provided APN, subscription not verified.
•The SGSN select the APN to be used to derive the GGSN address
•Wild Card APN: The user can select whichever APN he wants
Selection Algorithm
Y
MS Request ?
N
Y
N
Wild Card ?
N
SentByMS
Subscribed
Wild Card ?
Y
ChosenBySGSN
N
Single PDP in HLR?
Y
Subscribed
PDP Context
Activate Reject
Wild Card APN in HLR
IMSI .................... 46688xxxxxxxxxxxxx
SGSN ADDRESS ............
MT-SMS VIA SGSN ......... N
NETWORK ACCESS .......... BOTH
PDP CONTEXT ID .......... 1
PDP TYPE ................ IPv4
PDP ADDRESS .............
VPLMN ALLOWED ........... N
PRECEDENSE CLASS ........ 2
DELAY CLASS ............. 4
RELIABILITY CLASS ....... 2
PEAK THROUGHPUT CLASS ... 9
MEAN THROUGHPUT CLASS ... 31
APN ..................... *
3 PDP Context in HLR
IMSI .................... 46688xxxxxxxxxxxxx
SGSN ADDRESS ............
MT-SMS VIA SGSN ......... N
NETWORK ACCESS .......... BOTH
PDP CONTEXT ID .......... 1
PDP TYPE ................ IPv4
PDP ADDRESS .............
VPLMN ALLOWED ........... N
PRECEDENSE CLASS ........ 2
DELAY CLASS ............. 4
RELIABILITY CLASS ....... 3
PEAK THROUGHPUT CLASS ... 9
MEAN THROUGHPUT CLASS ... 31
APN ..................... internet
Aicent
Hutchison
GGSN
Roaming connectivity
Root DNS
Vlan
Gn Vlan
MS
IT Router
BSS
INTERNET
BG
HLR
SGSN
E1
Lambda ATM PVC
DCN Router
SS7
Gp VLAN1
BG1
.
MS1
MS1
Roaming APN :x.x.x.x
BG2
BSS
HLR
mnc088.mcc466.gprs
MS1
sgsn-01
ggsn01
ggsn02
BSS
sgsn
ggsn03
(Gn VLAN)
ggsn04
Router
ggsn01
(Gn VLAN)
Router
MS2
ggsn02
ggsn03
sgsn-02
Dns-1
Dns-2
Router
ggsn01
GRX connectivity (via internet)
VPN via internet
(Gn VLAN)
BSS
sgsn
ggsn02