Packet Switch Core in 2G and 3G network.pptx

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1. Packet Switching Core in 2G , 3G Networks Committed to Excellence In Mobile Networks

2. Introduction to PS Packet Switching Networks

3. Introduction to PS Packet Switching Networks 3 PSTN Circuit switched core Network Packet switched core Network Packet Data Network Evolved Packet Core Network BSC RNC GSM BTS UMTS Node B LTE eNB PCU UE UE UE 2G 3G 4G 🠶 Evolution of Core Network in All Mobile generations

4. Introduction to PS Packet Switching Networks 🠶 Review over CS Core Networks 2G Access Networks 3G Access Networks MSC SMSC HLR EIR GMSC FNR AUC Packet switched Network 4

5. Introduction to PS Packet Switching Networks 🠶 Circuit Switching vs Packet Switching Channel assignment Data Transmission Bit- Rate Charging Delay CIRCUIT SWITCHING NETWORK CS Networks is the Networks used in voice calls mainly PACKET SWITCHING NETWORK Channel for one user PS Networks is the Networks used in data sessions mainly Data Tx in one Path Fixed Bit- Rate Charging/Time Less Delay Connected to 2g , 3G Core Networks the Same in 2g , 3G Channel for Multiple users Data Tx in multiple paths Variable Bit- Rate Charging/Volume More Delay Connected to 2G , 3G Core Networks the same in 2G , 3G Access Networks Core Networks 5

6. PS Packet Switching Network Architecture

7. PS Packet Switching Network Architecture 🠶 What is Packet Switching ? Technology that allows data transfer between users in Cellular Networks. Benefits Higher data rates Resources are reserved only when needed Connection Setup time Flexibility to new services. 7

8. PS Packet Switching Network Architecture 🠶 Packet Switched Core Network 2G Access Networks 3G Access Networks SGSN HLR GGSN Circuit switched Network PDN 8 Packets Routing User Authentication Tracks User Location IP Packets Tunneling Mobility Management Stores users Profile Offline Charging Interface to External Network Packets Tunneling Hosts All External Networks APN’s

9. PDN HLR Site SGSN 9 PDN HLR Site RNC SGSN GGSN GGSN HPLMN VPLMN UE RNC User moves from HPLMN to VPLMN UE PS Packet Switching Network Architecture 🠶 Roaming in PS Core Networks

10. 10 PS Packet Switching Network Architecture 🠶 Roaming in PS Core Networks We Have two Types of Roamers: Out- Bound Roamers In-Bound Roamers

11. Site RNC SGSN GGSN 11 PDN Site RNC SGSN GGSN HPLMN VPLMN UE UE PS Packet Switching Network Architecture 🠶 Roaming in PS Core Networks PDN 1 2 3 4 Outbound Roamer 1 2 3 4

12. PS Packet Switching Network Architecture 🠶 DNS Domain Name server 🠶 Types of DNS Nodes Used ? 1. iDNS Internal DNS (Internal DNS) 2. eDNS External DNS (External DNS) . DNS SGSN 12 #2 Required IP Address

13. PS Packet Switching Network Architecture 🠶 iDNS ~ Internal DNS . GGSN PDN1 PDN2 PDN3 SGSN UE Requested APN 13 GGSN IP=1.1.1.1 GGSN GGSN IP=2.2.2.2 GGSN GGSN IP=3.3.3.3 iDNS Domain Name Example: Internet.t- Mobile

14. Site RNC SGSN HPLMN 14 PDN VPLMN UE PS Packet Switching Network Architecture 2 10 🠶 eDNS ~ External DNS iDNS eDNS GRX 3 4 5 6 7 8 9 1 Attach req. GGSN GGSN IP=1.1.1.1

15. PS Packet Switching Network Architecture 🠶 PCRF Policy and charging Rules functions PDN UE GGSN 15 Traffic Flow Traffic Flow PCRF PCC Rules Policy and charging Control Rules Means charging each different Traffic Stream with a specific rate. PCC Rules May instruct the GGSN to totally block the traffic or throttle it to a certain rate. RBN Rule Base Name It is a set of PCC Rules

16. PS Packet Switching Network Architecture 🠶 PCC Rules Policy & Charging Control PDN UE GGSN Traffic Flow Traffic Flow PCRF Rule Base Name (RBN) Mark WhatsApp with RG10 Mark Twitter and telegram with RG 20 Mark all other traffic with RG 50 Throttle file download traffic to 64 Kbps Block Skype Traffic 16

17. PS Packet Switching Network Architecture 🠶 DPI Deep packet Inspection PDN UE GGSN DPI Traffic Flow Traffic Flow 17

18. Identifiers in PS Core Network

19. Identifiers in PS Core Network 19 🠶 Location Identifiers PLMN Location Area Identifier (LAI) Routing area Identifier (RAI) Cell Global Identifier (CGI) Service Area Identifier (SAI)

20. Identifiers in PS Core Network 🠶 Public Land Mobile Network PLMN MCC (3 Digits) MNC (2or3 Digits) PLMN Address MCC Mobile Country Code : It is a unique identifier , given to every Country in the world. MNC Mobile Network Code: It is a unique code given to every network inside a country 2G Access Networks 3G Access Networks SGSN HLR Circuit switched Network GGSN PDN 20

21. Identifiers in PS Core Network 🠶 RAI & LAI Routing area identifier & Location Area Identifier. Every group of cells forms a RA . Every group of RA’s forms a LA. RA RA RA Location Area (LA) UE 21

22. Identifiers in PS Core Network 🠶 RAI & LAI MCC MNC LAC PLMN Address LAI MCC MNC LAC LAC 22 LAI RAI

23. Identifiers in PS Core Network 🠶 Cell Identifiers LAI LAI MCC MNC LAC SAC SAI MCC MNC LAC CI CGI 2G Site 3G Site 23

24. Identifiers in PS Core Network 24 🠶 UE Identifiers IMSI International Mobile Subscriber Identity MSISDN Mobile Station ISDN number IMEI International Mobile Equipment Identity P- TMSI Temporary Mobile Subscriber Identity

25. Identifiers in PS Core Network 🠶 IMSI 🠶 MSISDN MCC MNC MSIN PLMN Address IMSI Max 15 Digits CC NDC SN MSISDN 25

26. Identifiers in PS Core Network 26 🠶 IMEI It is an identifier for the hardware of the UE 🠶 IMEISV Represents the software version installed on the UE

27. Identifiers in PS Core Network 🠶 P- TMSI UE Attach Request (IMSI) TMSI Allocation SGSN 27

28. Identifiers in PS Core Network 28 🠶 NSAPI : Network Layer Service access point identifier. Identifier in the PDP context for each APN. 🠶 TI : Transaction Identifier Identifier for each user have a PDP Context PDP Identifiers

29. Interfaces in PS Core Network 29

30. Network Interfaces UE BSC SGSN GGSN HLR PDN RNC UE UE Site Site IU- PS RANAP BSSGP GB Gr MAP GTP GN GTP- U Gi VPLMN GGSN 30 GTP GP

31. Network Interfaces UE BSC SGSN GGSN PDN Site 31 CG Ga Ga Charging Gateway PSTN MSC Gs PCRF OCS

32. PDP Context in 2G,3G Networks & It’s Characteristics 32

33. PDP Context in 2G,3G Networks & It’s Characteristics 🠶 What is PDP Context ? UE SGSN GGSN PDP Context Corporate APN Other APN IP Address Internet IP Address Internet IP Address Range Internet APN Internet PDN PS Connectivity Service 33

34. PDP Context in 2G,3G Networks & It’s Characteristics 🠶 PDP Context Characteristics UE SGSN GGSN Internet APN IP Address Internet IP Address Internet IP Address Range Internet PDN PDP Context PDP Address QOS 34 Packet Data Protocol

35. PDP Context in 2G,3G Networks & It’s Characteristics 🠶 QOS Quality of Service During PDP Creation the GGSN should assign a quality of service to each PDP Based on this QOS the PDP priority will be determined. Most Important Attributes in QOS: Traffic Class The ‘ARP’ Value Maximum Bitrate UE SGSN GGSN Internet APN Internet IP Address Range PDP Context QOS Quality of Service 35

36. PDP Context in 2G,3G Networks & It’s Characteristics 36 🠶 1- Traffic Classes Conversational Streaming Interactive Background Traffic classes most important factor are distinguishable to is the Delay Sensitive traffic and Delay insensitive traffic.

37. PDP Context in 2G,3G Networks & It’s Characteristics 37 🠶 2- ARP Allocation and Retention Priority It is used when Network Nodes are not able for offering resources to all the requesting users by another meaning it is used when the Network resources are congested. In this case some users requests will be neglected and some will be processed. ARP value from 1 to 3 where 1 is the highest, 3 is the lowest. Each PDP have an ARP value 🠶 3- Maximum Bit-Rate It defines the maximum Bit-rate assigned for this PDP For the flow traffic over it

38. PDP Context in 2G,3G Networks & It’s Characteristics 38 🠶 Requested, Subscribed, Negotiated QOS Requested QOS: It is the QOS that is Requested by the User to get in the “Active PDP context Request Message”. Subscribed QOS : The QOS assigned to this User and exists in the UE Subscription information. Negotiated QOS : The QOS which exists During the Negotiation phase between Nodes

39. PDP Context in 2G,3G Networks & It’s Characteristics UE SGSN GGSN Internet APN Internet IP Address Range 🠶 PDP Address PDP Context PDP Address 39 During the PDP Context Activation the GGSN assigns an IP address to the PDP The PDP address is that IP Address. The UE will use this IP address while communication with the PDN. PDP Address Types: Dynamic Static

40. PDP Context in 2G,3G Networks & It’s Characteristics UE SGSN GGSN Internet APN Internet IP Address Range 🠶 PDP Address Dynamic IP Address PDP Context PDP Address 40 The GGSN assigns the IP from a pool of Ips configured in the GGSN. So in case of Dynamic every time the subscriber requests a PDP it takes Different IP. Static IP Address Static PDP address exists in the UE Subscription data.

41. PDP Context in 2G,3G Networks & It’s Characteristics UE SGSN GGSN Internet APN Internet IP Address Range 🠶 PDP Type PDP Context PDP Address 41 PDP Type is the type of the IP Address existing in the PDP. PDP Type exists in the subscription data of the UE. PDP Types: IPV4 IPV6 IPV4V6 (Dual Stack)

42. PDP Context in 2G,3G Networks & It’s Characteristics 🠶 Direct Tunneling reduces the load on SGSN. Let’s see what happens when using Direct tunneling and when not using it. 1. Direct Tunnel is not used Direct Tunneling is used Direct tunneling reduces the load on the SGSN RNC SGSN GGSN Control plane User plane 42 🠶 Direct Tunneling in 3G UE Site RNC SGSN GGSN UE Site PDN Internet

43. PDP Context in 2G,3G Networks & It’s Characteristics UE BSC SGSN GGSN GTP GTP GTP Tunnel RNC SGSN GGSN GTP GTP GTP Tunnel GTP GTP UE RNC GGSN GTP GTP Tunnel GTP UE GTP Tunnel 2G 3G 3G with direct Tunneling 43 🠶 GTP Tunnel & TEID PDP

44. PDP Context in 2G,3G Networks & It’s Characteristics UE BSC SGSN GGSN PDP GGSN TEID GTP Tunnel SGSN TEID TEID TEID 44 TEID = Tunnel End Point Identifier 🠶 GTP Tunnel & TEID

45. UE State Management in PS Core Networks 45

46. UE State Management in PS Core Networks 46 🠶 MM Mobility Management States in 2G 🠶 MM State is parameter that exists in user profile that usually exists in UE & SGSN. 🠶 MM States Values: Idle Ready Standby

47. UE State Management in PS Core Networks 🠶 MM States Values: Ready State The Network Knows the UE Exists in which Cell The packets can be normally sent between the UE and the SGSN. The UE enters the ready state when it makes the attach procedure. Cell Idle Ready Standby Attach RA 47 Ready timer Expiry PDU Transmission Detach 🠶 MM Mobility Management States in 2G

48. UE State Management in PS Core Networks 🠶 MM States Values: Standby State The Network Knows the UE Exists in which RA No packets is sent between the UE and the SGSN. There is a timer exists between the UE and SGSN called Ready timer if it expires without sending or receiving any packets ,the UE state Become Standby to save resources. Then if any packet is sent again between UE and SGSN , the MM state becomes Ready. Ready Standby Attach Ready timer Expiry PDU Transmission Detach 🠶 MM Mobility Management States in 2G Idle RA 48

49. UE State Management in PS Core Networks 🠶 MM States Values: Idle State The Network don’t Know about the existence of the UE. The UE moves to Idle state when it make the detach procedures. Ready Standby Attach Ready timer Expiry PDU Transmission Detach 🠶 MM Mobility Management States in 2G Idle 49

50. UE State Management in PS Core Networks 50 🠶 MM Mobility Management States in 3G 🠶 PMM State is parameter that exists in user profile that usually exists in UE & SGSN. 🠶 PMM States Values: PMM- Connected PMM- Idle PMM- Detached

51. UE State Management in PS Core Networks 🠶 MM States Values: PMM Connected State The Network Knows the UE Exists in which Cell The packets can be normally sent between the UE and the SGSN. The UE enters the PMM Connected state when it makes the attach procedure. Cell RA PMM- Detached PMM Connected PMM Idle PS Connection Release PS Connection Establishment 51 🠶 MM Mobility Management States in 3G

52. UE State Management in PS Core Networks 🠶 MM States Values: PMM Idle State The Network Knows the UE Exists in which RA No packets is sent between the UE and the SGSN. RA PMM- Detached PMM Connected PMM Idle PS Connection Release PS Connection Establishment UE New SGSN RNC PS Signaling Connection 52 🠶 MM Mobility Management States in 3G

53. UE State Management in PS Core Networks 🠶 MM States Values: PMM Detached State The Network don’t Know about the existence of the UE. The UE moves to PMM Detached state when it make the detach procedures or attach rejected by SGSN or RAU rejected. PMM- Detached PMM Connected PMM Idle PS Connection Establishment 🠶 MM Mobility Management States in 3G 53

54. UE State Management in PS Core Networks 🠶 PDP Context States:- PDP Context can be one of two states. These States are session management states. UE SGSN GGSN Internet APN Internet IP Address Range Internet PDN PDP Context 54 🠶 Session Management States

55. UE State Management in PS Core Networks PDN. ACTIVE INACTIVE PDP Context Activation PDP Context Deactivation or the MM States Moved to idle (2G) or PMM Detached (3G) UE INACTIVE State : User data can not be sent between the UE and the User Data 🠶 Session Management States 🠶 Session Management States :- Active State Inactive State PDN 55

56. UE State Management in PS Core Networks PDN. ACTIVE INACTIVE PDP Context Activation PDP Context Deactivation or the MM States Moved to idle (2G) or PMM Detached (3G) UE ACTIVE State : User data can be sent normally between the UE and the User Data 🠶 Session Management States 🠶 Session Management States :- Active State Inactive State PDN 56

57. PS Packet Switching Core Network Contexts 57

58. PS Packet Switching Core Network Contexts 🠶 MM Context is a Context that provides Mobility information of a MS. 🠶 PDP Context: is a context that supports packet delivery to PDN. MM Context MS SGSN GGSN 58 IMSI MM State TMSI IMEI MSISDN Routing Area VLR Address SGSN Address Authentication triplets KC Subscribed charging characteristics PDP Context MS SGSN PDP Context Identifiers PDP State PDP type PDP Address APN in use QOS Profile TEID Allowed VPLMN’s Subscribed charging characteristics

59. Mobility Management Timer Functions in PS Core 59

60. Mobility Management Timer Functions in PS Core Ready Timer: Ready Timer Starts after MS sends a packet or after SGSN receives a packet. It Controls the Time MS remains in Ready state. UE 🠶 Ready Timer SGSN 1- Send Packets 2- Ready Timer Starts 1- Receive Packets 60 2- Ready Timer Starts

61. Mobility Management Timer Functions in PS Core Periodic RA Update Timer: This Timer monitors the periodic Routing area update procedures. Upon Expiry, MS starts Periodic RA update. UE 🠶 Periodic RA Update Timer SGSN Periodic RA update Timer expires Periodic RA update req. 61

62. Mobility Management Timer Functions in PS Core Mobile Reachable Timer: This Timer monitors the periodic Routing area update procedures. Upon Expiry, SGSN Marks the Subscriber as unreachable. UE SGSN 🠶 Mobile Reachable Timer Mobile Reachable Timer expires SGSN puts unreachable flag on UE 62

63. Mobility Management Timer Functions in PS Core Implicit Detach Timer: This Timer monitors the reachability of the UE. If Timer Expires, SGSN Starts Detaching Subscriber UE 🠶 Implicit Detach Timer SGSN Unreachable Flag raised SGSN starts implicit detach timer SGSN starts Detaching subscriber 63

64. PS Packet Core Procedures

65. PS Packet Core Procedures 65 🠶 Attach Procedures For a UE to Start sending/Receiving packets with external PDN’s Packet data network. It should first Attach to the Network (SGSN) and then open a PDP context with the (GGSN).

66. PS Packet Core Procedures 🠶 Attach Procedures UE SGSN GGSN Internet APN Internet IP Address Range Internet PDN PDP Context 1. Attach Request 2. PDP Context Activation Request 66 Authentication Ciphering Location update TMSI Allocation

67. PS Packet Core Procedures 🠶 Signaling in Attach Procedure 1. Authentication 2. Location Update HLR BSC/RNC UE SGSN Attach Request Update Location Insert subscriber data Insert Subscriber data Ack. Update location Ack. Attach Accept Attach Complete 67 🠶 Attach Procedures Send Authentication info. EIR Send Authentication info. Ack. Send Authentication info. Send Authentication info. Ack. Check IMEI Check IMEI Ack.

68. PS Packet Core Procedures 🠶 Attach Procedures | UE Not Purged Purged means UE Detached, But It’s data still exists. So, SGSN Still have the MM Context & Authentication Parameters UE Attach Request Attach Accept Attach Complete SGSN MM Context 68

69. HLR UE BSC/RNC New SGSN Attach Request Insert subscriber data Insert Subscriber data Ack. Update location Ack. Attach Accept Attach Complete 69 PS Packet Core Procedures 🠶 Attach Procedures | SGSN changed Send Authentication info. Send Authentication info. Ack. Send Authentication info. Send Authentication info. Ack. EIR Check IMEI Check IMEI Ack. Old SGSN Identification Req. Identification Resp. Send Identity Req. Send identity Resp. Update Location Cancel loc. Cancel loc. Ack.

70. PS Packet Core Procedures 70 🠶 Combined Attach | CS + PS Send Authentication info. Send Authentication info. Ack. Send Authentication info. Send Authentication info. Ack. Check IMEI Check IMEI Ack. New SGSN Old SGSN Identification Req. Identification Resp. Send Identity Req. Send identity Resp. Update Location Request UE BSC/RNC Attach Request Attach Accept Attach Complete MSC HLR EIR Cancel loc. Cancel loc. Ack. Insert Subscriber data Insert subscriber data Ack. Update location Ack. Update Location Request Update Location ISD ISD Ack. UPL Ack Update Location Accept

71. PS Packet Core Procedures 71 🠶 Detach Procedures 🠶 Detach Procedures : Means De-registering the UE from the Network and deleting any existing PDP for it. The Detach Procedure may be initiated from the UE , SGSN & HLR. UE : power off or SIM card removed from it. SGSN : Can’t afford the required resources for this UE. HLR : UE Subscription information is changed and HLR Needs to Detach the UE and to make the SGSN retrieve the new subscription information in the next attach .

72. UE BSC/RNC SGSN PS Packet Core Procedures 🠶 Detach Procedures | MS initiated Detach Detach Request Detach accept GGSN MSC- S Delete PDP Context Req. Delete PDP Context Res. IMSI Detach indication GPRS Detach indication PS Signaling connection release 72

73. UE BSC/RNC SGSN PS Packet Core Procedures 🠶 Detach Procedures | SGSN initiated Detach Detach Request Detach accept GGSN MSC- S Delete PDP Context Req. Delete PDP Context Res. GPRS Detach indication PS Signaling connection release 73

74. UE BSC/RNC SGSN PS Packet Core Procedures 🠶 Detach Procedures | HLR initiated Detach Detach Request Detach accept GGSN MSC- S HLR Cancel Location Cancel Location Ack. Delete PDP Context Req. Delete PDP Context Res. IMSI Detach indication GPRS Detach indication PS Signaling connection release 74

75. PS Packet Core Procedures 75 🠶 Purge Procedures After the UE has detached. The SGSN may be configured to immediately delete the Detached UE contexts by using the Purge Procedures . It also may be configured to keep them for a determined amount of time, Keeping the existing contexts of UE will reduce the signaling towards the HLR Next Time.

76. PS Packet Core Procedures UE RNC/BSC SGSN Purge MS Ack. GGSN Purge MS HLR IMSI 76 2. HLR replies with acknowledgement Of Deletion. 🠶 Purge Procedures Signaling 1. First The SGSN Deletes the contexts of this UE and send a Purge MS to the HLR including the UE IMSI.

77. PS Packet Core Procedures UE RNC SGSN GGSN RAB Assignment request Establish radio bearer 77 🠶 PDP Context Activation Signaling Activate PDP Context Request DNS Requested APN GGSN IP Address Create PDP Context Request Activate PDP Context Response RAB Assignment Response update PDP Context Request update PDP Context Response Activate PDP Context Accept PCRF OCS CCR- I CCA- I CCR- I CCA- I

78. PS Packet Core Procedures RNC SGSN Modify PDP context request Modify PDP Context accept GGSN Update PDP Context request Update PDP Context response RAB Modification Update PDP Context request Update PDP Context response 78 🠶 PDP Context Modification It Is used to modify the values of the Parameters of the PDP Context Between the Nodes . PDP Context Modification can be initiated from the UE , RNC , SGSN , GGSN . UE “UE Initiated PDP Context Modification” 1. UE sends “Modify” including the requested Changing parameters. 2. GGSN Updates it and send it back.

79. PS Packet Core Procedures PDN 🠶 PDP Context During Active session UE RG:10 RG:20 DPI GGSN GGSN OCS CCR- U CCA- U RG20 CCR- U Quota=100MB CCA- U RG20 CCR- U Error Code=Credit limit reached CCA- U Quota=100MB RG10 79 Rule Base Name :1 Mark WhatsApp with RG10,Free of charge Mark Twitter with RG20 , Not free of charge.

80. PS Packet Core Procedures PDP Context De- Activation UE Initiated the PDP Context Deactivation Incase of 3G Network ,RAB release occurs. UE RNC SGSN Delete PDP Context response GGSN Deactivate PDP context request Delete PDP Context request Deactivate PDP Context accept RAB Release 80 OCS PCRF CCR- T CCA- T CCR- T CCA- T

81. 2 Inter SGSN RAU Intra SGSN RAU PS Packet Core Procedures 🠶 Routing Area Update 🠶 RA & RAU Every group of sites are called RA Routing area Group of RA’s are called Location For a UE who moves from one RA to another This is done By RAU Routing area update

82. Routing Area Update Signaling HLR UE BSC/RNC New SGSN RAU Request Authentication Update location Ack. RAU Complete RAU Accept P- IMSI, Old RAI,RAI Old SGSN MM Context , PDP Context P- IMSI SGSN Context Request SGSN Context Response GGSN SGSN Context Ack. Forward Packets Update PDP Request Update PDP Context Response Update Location Cancel Location Cancel Location Ack. Insert subscriber data Insert Subscriber data Ack. 82

83. PS Packet Core Procedures When UE is in PMM Idle State so the PS the PS Signaling connection is not established in Turn the UE can not send User data . The UE Initiates The Service request procedure in order to establish the PS signaling connection and move to PMM- Connected State. PMM- Detached PMM Connected PMM Idle PS Connection Release PS Connection Establishment UE SGSN RNC PS Signaling Connection 83 🠶 Service Request

84. PS Packet Core Procedures UE SGSN RAB assignment Response GGSN SGSN Initiated PDP Context Modification RAB Assignment Request Radio bearer Setup HLR RNC/BSC Service Request Uplink PDU Security Functions 84 🠶 Service Request

85. PS Packet Core Procedures 🠶 Paging Procedures Cell RA RA Cell Cell Cell Cell Cell Cell Cell SGSN Paging 85

86. PS Packet Core Procedures 🠶 Signaling of Paging Procedure in 3G UE RNC SGSN Service Request DL PDU Paging Request Paging Request 86

87. PS Packet Core Procedures 🠶 Signaling of Paging Procedure in 2G UE BSC SGSN DL PDU Paging Request Paging Request LLC Frame LLC Frame 87

88. PS Packet Core Key Features

89. PS Packet Core Key Features SGSN SGSN SGSN SGSN SGSN SGSN SGSN SGSN SGSN Pool:1 89 Pool:3 🠶 SGSN in Pool 🠶 SGSN in a Network May be configured in a Pool: Pool:2

90. PS Packet Core Key Features 🠶 SGSN in Pool Benefits: 🠶 Load Balancing: Instead of connecting RNC or BSC to One SGSN they will connect to a pool of SGSN’s. 🠶 Redundancy: If one SGSN went down the Other SGSN can handle the sessions Instead of it. SGSN SGSN SGSN Pool:1 90 🠶 SGSN in Pool

91. PS Packet Core Key Features 🠶 NRI: Every SGSN inside a pool is identified by a unique identifier Called the NRI NRI is part of the TMSI assigned from SGSN to UE during Attach Procedure. So the RNC or BSC can know the serving SGSN from the TMSI SGSN SGSN Pool:1 SGSN NRI NRI NRI 91 🠶 SGSN in Pool

92. PS Packet Core Key Features 92 🠶 Charging in PS Core 🠶 Offline Charging Doesn’t affect data session in real time. 🠶 Online charging Affects data session in real time. .

93. PS Packet Core Key Features 🠶 Charging Models 🠶 Charging Types: Volume based Charging Time Based charging Event based Charging . 93 UE SGSN GGSN PDN PDP Context Internet APN Corporate APN Other APN Internet IP Address Range