Introduction of PS Core Network Elements and little bit of EPC/LTE Network. This is introductory slides pack for a 10 class/slides set for detail introduction of 2G/3G and LTE PS Core Network.

1. Mustafa Golam
PS CoreOverview

2. Training Schedule
#Week Day Date Duration Time Basic/Advance
WK-01 Fri 14thJuly,2017 2Hours 11:00-13:00GMT+3 Basic
WK-02 Fri 21stJuly,2017 2Hours 11:00-13:00GMT+3 Basic
WK-03 Fri 28thJuly,2017 2Hours 11:00-13:00GMT+3 Basic
WK-04 Fri 4thAug,2017 2Hours 11:00-13:00GMT+3 Advance
WK-05 Fri 11thAug,2017 2Hours 11:00-13:00GMT+3 Advance
WK-06 Fri 18thAug,2017 2Hours 11:00-13:00GMT+3 Advance
WK-07 Fri 25thAug,2017 2Hours 11:00-13:00GMT+3 Basic
WK-08 Fri 1stSep,2017 1Hour 11:00-13:00GMT+3 Advance
WK-09 Fri 1stSep,2017 2Hours 11:00-13:00GMT+3
WK-10 Fri 8thSep,2017 2Hours 11:00-13:00GMT+3 Basic
WK-11 Fri 15thSep,2017 2Hours 11:00-13:00GMT+3 Advance
WK-12 Fri 22ndSep,2017 1Hour 11:00-13:00GMT+3 Advance
WK-13 Fri 29thSep,217 1hours 11:00-13:00GMT+3
Subject/ Topics
PacketCore NetworkBasics
GatewayGPRSSupportNode
GatewayGPRSSupportNode - Part03- PISC
GatewayGPRSSupportNode - Part02
PS Core / EPC-Competence DevelopmentTraining -2017
PSCore Course - Exam
IntroductionTo LTE EPC Network- Part03
ServingGPRSSupportNode - SGSN
Course Exam
SAPC Par02
IntroductionTo LTE EPC Network- Part01
IPWorks
SAPC Part01
IntroductionTo LTE EPC Network- Part02

3. BasicGPRS NetworkArchitecture
SGSN GGSN
Gi (IP)Gn
Gs
Gb
Gp
Gr (MAP)
IP
Network
Inter PLMN Backbone
Network
IP
MSC/VLRBTS BSC HLR
MAP
MS
RNCRAN node B
Gp
Iu

4. MS BTS BSC
RNCNODE-BMS
SGSN GGSN
SGSN GGSN
MSC
SCP/Camel
HLR OSS
Corporate
LAN
Gs
SMS
Um Abis Gb
Ge
Gn
GomGr
Gn
Gn
Gn
Gn
Um Iub Iu
Gi
Gi
Gd
GSM
WCDMA ISP
PCRF
ExtendedLogical Network Architecture

5. Functional view on GPRS
Local
area
network
Server
Router
Local
area
network
Server
Router
Corporate 2
Corporate 1
Intra-PLMN
backbone
network
(IP based)
Serving GPRS
Support Node
(SGSN)
Point-To-
Multipoint
Service
Center
(PTM SC)
Gateway GPRS
Support Node
(GGSN)
GPRS
INFRASTRUCTURE
HLR/AuC
MSC
BSCBTS Packet
networkPSTN
Packet
networkSS7
Network
Packet
network
Data
network
(Internet)
Packet
network
Data
network
(X.25)
Packet
network
Inter-PLMN
Backbone
network
Border
Gateway (BG)
Gb
Gr Gd
Gi.IP
Gi.X.25
Firewall
Firewall
Firewall
Um
R/S
SMS-GMSC
Gr Gd
Gs
Gs
Gp
Gn
Gn
EIR
MAP-F

6. Protocol Level Logical NetworkArchitecture

7. SGSN- Functionality
SGSN – Serving GPRS Support Node
SGSN handles the communication with MSs and the establishment of the connection
between an MS and the PDN.
Functionalities at a glance:
•Serves MSs in SGSN area
•Mobility Management functions, e.g
•Update Location, Attach, Paging,..
•Security and access control:
•Authentication, Cipher setting, IMEI Check...
•Routing / Traffic-Management
•Collecting charging data
•Realises Interfaces: Gn, Gb, Gd, Gp, Gr, Gs, Gf
•Controls subscribers in its service area (SLR)
•Lawful Interception
• Routing Area Update (Location Registration)
• Location Update for CS
• Attach / Detach
• P-TMSI allocation / reallocation
• Authentication
• Paging (PS & CS)
Mobility Management
• PDP context activation
• PDP context modification
• PDP context cancellation
Session Management
Ericsson MKVI
Huawei SGSN

8. GGSN- Functionality
GGSN– Gateway GPRS Support Node
SGSN handles the communication with MSs and the establishment of the
connection between an MS and the PDN.
Functionalities at a glance:
•Acts as an interface and a router to external networks
•It contains routing information for GPRS mobiles...
•Tunnel packets through the IP based internal backbone
•Collects charging data
•Packet filter for incoming traffic
•Packet inspection
•Gateway with online charging system
• PDP context activation
• PDP context modification
• PDP context cancellation
Session Management
M120 GGSN
UGW9811 PGW

9. DNS- Functionality
DNS– Domain Name System
DNS interface with SGSN to perform some very important functionality
Functionalities at a glance:
•Resolve the APN to a GGSN IP in the PDP active procedure
•Resolve the RAI to a SGSN IP in the inter-SGSN RAU procedure
•Resolve the RNCID to a SGSN IP in the relocation procedure (UMTS)
IPWorks DNS on SUN HW

10. PCRF – Functionality
PCRF– Policy and Charging Rule Function
PCRF is a Policy Server. It provides Centralized Policy Management
according to the 3GPP Policy and Charging Architecture
Functionalities at a glance:
•Service Authorization
•Redirection
•Bandwidth Management
•Service Based Routing
•Content Filtering
•Charging
•Control based on usage
E// SAPCH// UPCC PCRF

11. Other Elements - Functionality
BGW– Border Gateway
Not defined within GPRS Network
Functionalities at a glance:
•Routes packets from SGSN/GGSN of one operator to a
SGSN/GGSN of another operator.
CGW– Charging Gateway
Not defined within GPRS Network
Functionalities at a glance:
•Collects charging information from SGSNs and GGSNs

12. GPRSAttach
•When a MS is turned on, the first function it performs is a GPRS attach
•GSM access authentication (towards Home Network, HLR
(Authentication Center - AuC))
•User profile is downloaded from HLR to the serving SGSN
•When the GPRS attach is complete, the MS is physically connected to the
visited network

13. AttachProcedure
1.Attach Request
MS BSS New SGSN Old SGSN GGSN EIR
New
MSC/VLR
HLR old
MSC/VLR
2. Identification Request
3. Identification Response
3. Identity Request
3. Identity Response
4. Authentication
5. IMEI check
6a. Update Location
6b. Cancel Location
6c. Cancel Location ACK
6d. Insert Subscriber Data
6d. Insert Subscriber Data ACK
6e. Update Location ACK
8. Attach Accept
9. Attach Complete 10. TMSI Reallocation complete
7c.
Cancel
Location
7d.ACK
7a. Location Update Request
7b. Update Location
7e. Insert Subscriber data
7h. Location Update Accept
7f. Insert Subscriber data ACK
7b. Update Location ACK

14. The Packet Data Protocol (PDP) Context
•In order to be able to send and receive data, the mobile must set-up a
packet data bearer
•The PDP bearer is associated with contexts in each nodes that data are
traversing.
•The bearer is set-up via “PDP context activation” procedures
•PDP context describes requirements of the connection to the packet
networks: Type, network address, Access Point Name (APN), QoS, etc.
•SGSN validates request against subscription information downloaded
from HLR during GPRS Attach
•Access point name sent to DNS, IP address(s) of suitable GGSNs
returned
•Logical connection using GPRS tunnels (GTP) between SGSN and GGSN
•IP address allocated (GGSN pool, DHCP, RADIUS)

15. PDP Context Activation

16. Mobile Address Allocation
GGSN Address Pools
Static, dynamic allocation at GPRS packet data activation
HLR
The HLR may keep a static IP address that is fetched by the SGSN at
GPRS attach
RADIUS
The GGSN may interact with an external AAA server in order to perform
AAA functions as well as dynamic IP address allocation at GPRS packet
data activation
DHCP server
The GGSN may interact with an
external DHCP server to perform
dynamic IP address allocation at
GPRS packet data activation

17. PLMNRoaming
HPLMN
GGSNMS
UPLMN
GGSNSGSN
GGSNSGSNGGSN
VPLMN
GGSNSGSN
ISP
DNS
DNS
APN available in Home PLMN only

18. Roaming Billing
• TAP - Records (Transferred Account Procedure)
– Existing methods of TAP exchanges shall be used
– TAP File Spec 3 required - GPRS enhancements like: data
volume, IP address, APN, etc.
• Different concepts to existing TAP Record Procedures
– Partial Records Generated + Data volume counts
– CDRs from HGGSN and VSGSN - different records from
different networks for the same connection.

19. 2G Mobility StateTransition
PDU transmission
Implicit Detach
or
Cancel Location
GPRS Attach
READY timer expiry
or
Force to STANDBY
GPRS Detach GPRS Attach
PDU reception
GPRS Detach
or
Cancel Location
MM State Model of MS MM State Model of SGSN
IDLE
READY
STANDBY
IDLE
READY
STANDBY
READY timer expiry
or
Force to STANDBY
or
Abnormal RLC condition

20. 3G Mobility StateTransition
PMM-
DETACHED
PS Attach
PS Signalling
Connection Release
PS Signalling
Connection Establish
PS Detach
PMM-
CONNECTEDPMM-IDLE
Detach,
PS Attach Reject,
RAU Reject
PMM-
DETACHED
PS Detach
PMM-
CONNECTED
Serving RNC
relocation
3G-SGSN MM StatesMS MM States
SM-ACTIVE or
INACTIVE
SM-ACTIVE or
INACTIVE
SM-ACTIVE or
INACTIVE
SM-ACTIVE or
INACTIVE
Detach,
PS Attach Reject,
RAU RejectPS Attach
PS Signalling
Connection Establish
PS Signalling
Connection Release
PMM-IDLE

21. Routing Area UpdateProcedure
MS
RAI 2 RAI 4
SGSN SGSN
RAI 1 RAI 3
cell
Intra SGSN-RAU
Inter SGSN -RAU
Gn

22. Paging for GPRS (2G)
5. Any LLC Frame
4. Any LLC Frame
3. GPRS Paging Request
2. Paging Request
1. PDP PDU
MS BSS SGSN
STANDBY
READY
(IMSI, P-TMSI,
Area, Channel
Needed, QoS,
DRX
Parameters)
(Receive Ready or
Information frame)

23. Paging Initiated By PCN(3G)
4. Service Request
4. Service Request
3. Paging Type1
2. Paging
MS RNC MSC/VLR
3G-SGSN
1. PDP PDU or
Downlink signalingPMM IDLE
PMM
CONNECTED
(PCH paging)
(IMSI, P-TMSI,
Area, CN
Domain
Indicator, DRX
parameters)
› PS Paging Initiated by 3G-SGSN without RRC Connection for CS

24. Learning what is EPC?
EPC- Evolved Packet Core
Current system-3G is moving to LTE gradually. According to this new
system, every network system will be in process of change.
Core Network will be changed in EPC which stands for Evolved Packet
Core. It’s called SAE (system architecture evolution) too.
EPC consists of MME, S-GW, P-GW.
Here,
- MME (Mobility Management Entity)
---> for bearer control
- S-GW (Serving Gateway)
---> for routing and transfer user packet
- P-GW (Packet Gateway)
---> for carrying User packet

25. LTE/EPCarchitecture
Let’s compare current system with EPCs!!
GGSN
SGSN
RNC
3G
MME
P-GW
S-GW
LTE
Node b/ hspa
enode b
U-plane
C-plane
* Red Character: Interface
S11
S1-C
S1-U
S10
HLR/HSS
S6a
X2
Direct Tunnel ??
means
- U-plane is connected between
P-GW and eNodeB directly.
Merit:
- Speed up the wireless part.
- Simplify the Dimensioning and
Decrease the delay
S-GWS5
V-PLMN
S8
S5

26. NetworkEvolution
2008/0920072000
3GPP Rel-99 3GPP Rel-7 3GPP Rel-8
NodeB
RNC
SGSN
GGSN
NodeB
RNC
SGSN
GGSN
eNodeB
MME
P+S-GW
User plane directly
between RAN and
GW!
User plane
essentially
outside SGSN!
User plane traffic
through all nodes
PDNPDNPDN
LTE
EPC
EPS
SGSN
GGSN
RNC
SGSN
GGSN
NodeB
RNC
SGSN
GGSN

27. EPCAttachProcedure
UE eNodeB MME HSS SGW PGW PCRF
NAS: Security Mode Complete
S1AP: Uplink NAS Transport
NAS: Attach Accept
S1AP: Initial Context Setup Request
Dia: Update Location (MME ID, IMSI)
Dia: Update Location Answer (APN, QoS, Charging attribution)
GTPCv2: Create Session Request (MME F-TEID(S11), PGW IP address (S5-C),
PDN type, IMSI, bearer QoS, EBI)
GTPCv2: Create Session Request (MME F-TEID(S11), PGW IP address
(S5-C), PDN type, IMSI, bearer QoS, EBI)
Dia: Control Credit Request
(Initial Request, APN, IMSI, QCI&ARP, APN-AMBR)
Dia: Control Credit Answer
(Initial Request, QCI&ARP, APN-MBR, Event-
Trigger)
GTPCv2: Create
Session Response
(Cause, PGW F-
TEID(S5-C, S5-U),
UE-IP address, Bearer
QoS, EBI)
GTPCv2: Create Session Response
(cause, SGW F-TEID(S11, S1-U), UE IP address,
Bearer QoS, PDN F-TEI D(S5-C, S5-U), EBI )
NAS: Attach Accept
S1AP: Initial Context Setup Response
NAS: Attach Complete
NAS: Attach Complete
S1AP: Uplink NAS Transport
GTPCv2: Modify Bearer Request
GTPCv2: Modify Bearer Response

28. 3G
EPCTraffic Cases
2G/3G/EPS Interworking
Iub
Gn
X2
S1-UP
UTRAN
Internet
Evolved
Packet
Core
GPRSPacketCore
S3
S1-CP
eUTRAN
X2
S4
Iub
Iur
Iu
LTE
SGi
S11
EPC
Gb
Abis
2G
GERAN
MME
Serving GW
(S-GW)
GGSN
SGSN
BSC
RNC RNC
PDN GW
(P-GW)
S5/S8

29. Automation
GGSN CDR was piling up in the system because after successfully copying the CDRs mediation moved the CDR file from
default location to GGSN /var/log/CDR_collected. To maintain safe disk usage an automated procedure was required.
So a script was prepared to handle this requirement.
#!/bin/sh
#################################################################
# SCRIPT: remove_old_GGSN_CDR_v0.sh #
# PURPOSE: Remove old CDRs from CDR path in GGSN #
# Author: Mustafa Golam #
#################################################################
now="$(date)"
hostn="$(hostname)"
echo "starting deletion of CDR backlog $now for GGSN $hostn" >>/var/log/CDR_Deleteion_Log
cd /var/log/CDR_collected
wd="$(pwd)"
echo "Current Directory $wd" >> /var/log/CDR_Deleteion_Log
#verification
countlines="$(ls -ltr |wc -l)"
echo "Total CDR files found $countlines" >>/var/log/CDR_Deleteion_Log
#Deletion
/usr/bin/find . -type f -mtime +3 -exec /bin/rm -rf {} ;
echo "Old CDR File Deletion Completed and Remaining CDR Files $countlines" >>/var/log/CDR_Deleteion_Log
The Script
Managing CDR directory usage by GGSN cronjob

30. When you’re confused
Q??