Product Description
GSM-R SGSN9810 Product Description
Issue
V1.0
Date
2009-03-30
HUAWEI TECHNOLOGIES CO., LTD.
Huawei Technologies Co., Ltd. provides customers with comprehensive technical support and service. Please feel free to contact our local office or company headquarters.
Huawei Technologies Co., Ltd. Address:
Huawei Industrial Base Bantian, Longgang Shenzhen 518129 People's Republic of China
Website:
http://www.huawei.com
Email:
[email protected]
Copyright © Huawei Technologies Co., Ltd. 2009. All rights reserved. No part of this document may be reproduced or transmitted in any form or by any means without prior written consent of Huawei Technologies Co., Ltd.
Trademarks and Permissions and other Huawei trademarks are trademarks of Huawei Technologies Co., Ltd. All other trademarks and trade names mentioned in this document are the property of their respective holders.
Notice The information in this document is subject to change without notice. Every effort has been made in the preparation of this document to ensure accuracy of the contents, but all statements, information, and recommendations in this document do not constitute the warranty of any kind, express or implied.
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About This Document Author Prepared by
Date
Liao Huanran
Reviewed by Approved by
2009-03-30
Date Date
Wang Zhoujie
2009-03-30
Summary This document provides information for the product function, features, technical indexes, and structure of the SGSN9810 serving GPRS support node so that you can have a global view of the SGSN9810. This document includes: Chapter
Details
1 Overview
Describes the position and application of the SGSN9810 in a network.
2 Product Feature
Describes the product features of the SGSN9810.
3 System Structure
Describes the hardware, software, and logical structure of the SGSN9810.
4 Function
Describes the product features of the SGSN9810.
5 Operation and Maintenance
Describes the operation and maintenance of the SGSN9810.
6 Reliability
Describes the hardware and software reliability of the SGSN9810.
7 Technical Index
Describes the technical indexes of the SGSN9810.
8 Installation
Describes the fundamental features for the hardware and software installation of the SGSN9810.
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History Issue
Details
Date
Author
Approved by
V1.0
Creation
2009-03-30
Liao Huanran
Wang Zhoujie
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Contents 1 Introduction to the SGSN9810 .................................................................................................... 8 1.1 Structure of a GPRS/UMTS Network .............................................................................................................. 8 1.2 Huawei GPRS/UMTS CN-PS Solution ........................................................................................................... 9 1.2.1 SGSN .................................................................................................................................................... 10 1.2.2 GGSN.................................................................................................................................................... 10 1.2.3 HA......................................................................................................................................................... 10 1.2.4 CG ......................................................................................................................................................... 11 1.2.5 AAA Server ........................................................................................................................................... 11 1.2.6 DNS Server ........................................................................................................................................... 11 1.2.7 BG ......................................................................................................................................................... 11 1.3 Overview of the SGSN9810 ........................................................................................................................... 12
2 Key Benefits ................................................................................................................................. 15 2.1 Large Capacity and High Integration ............................................................................................................. 15 2.2 High-Speed Hardware Forwarding ................................................................................................................ 15 2.3 Supporting Boards of 750C Series ................................................................................................................. 15 2.4 Standard Protocol Interfaces .......................................................................................................................... 16 2.5 Abundant Physical Interfaces ......................................................................................................................... 17 2.6 Rich Services and Functions .......................................................................................................................... 17 2.7 Accurate Clock System .................................................................................................................................. 18 2.8 Easy Operation and Maintenance ................................................................................................................... 18 2.9 High Reliability .............................................................................................................................................. 19
3 System Structure ......................................................................................................................... 20 3.1 Hardware Configuration ................................................................................................................................. 20 3.1.1 Cabinet Configuration ........................................................................................................................... 20 3.1.2 Switching Subrack ................................................................................................................................ 22 3.1.3 Basic Subrack........................................................................................................................................ 23 3.1.4 Extended Subrack ................................................................................................................................. 25 3.2 Software Structure .......................................................................................................................................... 26 3.3 Logical Structure ............................................................................................................................................ 27 3.3.2 Switching Subsystem ............................................................................................................................ 28 3.3.3 PS Transfer Subsystem.......................................................................................................................... 28 3.3.4 Gb Interface Processing Subsystem ...................................................................................................... 28 3.3.5 Signaling Processing Subsystem ........................................................................................................... 29 3.3.6 Lawful Interception Subsystem............................................................................................................. 29
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3.3.7 Charging Subsystem ............................................................................................................................. 29 3.3.8 Iu Interface Control Plane Processing Subsystem ................................................................................. 29 3.3.9 GTP Control Plane Processing Subsystem ............................................................................................ 29 3.3.10 Operation and Maintenance Subsystem .............................................................................................. 29 3.3.11 Clock Subsystem ................................................................................................................................. 29
4 Services and Functions ............................................................................................................... 30 4.1 Services .......................................................................................................................................................... 30 4.1.1 IP/PPP Bearer Services ......................................................................................................................... 30 4.1.2 Short Message Services ........................................................................................................................ 31 4.1.3 Location Services .................................................................................................................................. 32 4.1.4 CAMEL Phase 3 Services ..................................................................................................................... 33 4.1.5 Lawful Interception ............................................................................................................................... 34 4.2 Functions ........................................................................................................................................................ 35 4.2.1 Mobility Management ........................................................................................................................... 36 4.2.2 Session Management............................................................................................................................. 36 4.2.3 Routing.................................................................................................................................................. 36 4.2.4 IPv6 Support ......................................................................................................................................... 37 4.2.5 IPSec and LLC Encryption ................................................................................................................... 38 4.2.6 Charging ................................................................................................................................................ 38 4.2.7 QoS ....................................................................................................................................................... 39 4.2.8 Iu-FLEX/Gb-FLEX ............................................................................................................................... 40 4.2.9 RAN Sharing in Connected State .......................................................................................................... 41 4.2.10 MVNO ................................................................................................................................................ 42 4.2.11 UESBI-Iu ............................................................................................................................................ 43 4.2.12 Multi-SPs and 2 Mbit/s Signaling Links ............................................................................................. 44 4.2.13 NTP Client Functions .......................................................................................................................... 45 4.2.14 Network-Assisted Cell Change ........................................................................................................... 47 4.2.15 SIGTRAN Support.............................................................................................................................. 47 4.2.16 Gb over IP ........................................................................................................................................... 49 4.2.17 Differential Services ........................................................................................................................... 50 4.2.18 Handover Strategy Control ................................................................................................................. 50 4.2.19 Enhanced MBMS ................................................................................................................................ 51 4.2.20 Network Share .................................................................................................................................... 52 4.2.21 Security Solution ................................................................................................................................. 53 4.2.22 Bidirectional Forwarding Detection (BFD) ........................................................................................ 55 4.2.23 One Tunnel .......................................................................................................................................... 55 4.2.24 SGSN N+1Backup .............................................................................................................................. 56 4.2.25 Multi SIM............................................................................................................................................ 56
5 Operation and Maintenance ..................................................................................................... 58 5.1 O&M System ................................................................................................................................................. 58 5.2 Configuration Management............................................................................................................................ 59
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5.3 Equipment Management ................................................................................................................................ 59 5.4 Tracing Management ...................................................................................................................................... 59 5.5 Performance Management.............................................................................................................................. 60 5.6 Fault Management .......................................................................................................................................... 60 5.7 Security Management ..................................................................................................................................... 60 5.8 CHR ............................................................................................................................................................... 60 5.9 SSL ................................................................................................................................................................. 61 5.10 SSH .............................................................................................................................................................. 62 5.11 Online Help .................................................................................................................................................. 63
6 Reliability ..................................................................................................................................... 64 6.1 Hardware Reliability ...................................................................................................................................... 64 6.1.1 Board Hot Backup ................................................................................................................................. 64 6.1.2 ASIC Technology .................................................................................................................................. 64 6.1.3 Quality Components ............................................................................................................................. 64 6.1.4 Load Sharing ......................................................................................................................................... 65 6.1.5 Power Supply Reliability ...................................................................................................................... 65 6.2 Software Reliability ....................................................................................................................................... 65 6.2.1 Reliability Building at Different Phases ................................................................................................ 65 6.2.2 Error Tolerance ..................................................................................................................................... 65 6.3 Charging Reliability ....................................................................................................................................... 66
7 Technical Specifications ............................................................................................................ 67 7.1 Performance Specifications ............................................................................................................................ 67 7.2 Physical Interfaces ......................................................................................................................................... 67 7.3 Clock Indexes ................................................................................................................................................. 68 7.4 Engineering Specifications ............................................................................................................................. 70 7.4.1 Power Consumption .............................................................................................................................. 70 7.4.2 Dimensions and Weight of Cabinets ..................................................................................................... 71 7.4.3 Environment Requirements ................................................................................................................... 71 7.5 Reliability Specifications ............................................................................................................................... 72
8 Installation.................................................................................................................................... 73 A Acronyms and Abbreviations .................................................................................................. 74
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Introduction to the SGSN9810
The SGSN9810 is a core device of the packet domain of the GPRS/UMTS core network.
1.1 Structure of a GPRS/UMTS Network The current wireless technology is evolving from 2G global system for mobile communications (GSM) to 3G UMTS by way of 2.5G GPRS. Mobile communication networks now cover large areas, transfer data in high speed, and can access the Internet. These networks provide a wide range of multimedia services such as voice, data, and video and can be accessed anytime and anywhere. Figure 1-1shows the structure of a GPRS/UMTS network.
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Figure 1-1 Structure of a GPRS/UMTS network
CN-CS
RAN GSM/GPRS BSS
MGW/MSC Server
BSC
HLR SMS-GMSC SMS-IWMSC GMSC
MS
PSTN, ISDN
BTS
Billing Center
SS7 EIR
UMTS UTRAN RNC CG
MS
NodeB SGSN
Firewall
DNS Server
Core Network
Firewall
GGSN/ HA FA
Other PLMN BG DNS Server
CN-PS
Internet, Intranet, etc.
WAP Gateway
AAA Server
As shown in Figure 1-1, a GPRS/UMTS network consists of the following parts:
Mobile station (MS): user equipment capable of originating and receiving calls over the air interface. To handle data services, the MS establishes a logical link with the packet switched (PS) domain.
Radio access network (RAN): handles all radio related functions.
Core network-circuit switching (CN-CS): provides circuit services and connects to external circuit switched networks, such as a public switched telephone network (PSTN).
CN-PS: provides packet data services and connects to external public data networks (PDNs), such as the Internet.
1.2 Huawei GPRS/UMTS CN-PS Solution The Huawei GPRS/UMTS CN-PS consists of the following main network entities:
Serving GPRS support node (SGSN)
Gateway GPRS support node (GGSN) and foreign agent (FA)
Home agent (HA)
Charging gateway (CG)
Authentication, authorization, accounting (AAA) server
Domain name system (DNS) server
Border gateway (BG)
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The CN-PS offers the means for an MS to access an external PDN. It provides packet data services and charging services, such as prepaid and postpaid services.
1.2.1 SGSN The SGSN is a functional entity that provides packet data services. It forwards incoming and outgoing internet protocol (IP) packets to the mobile stations (MSs) within its service area. The SGSN provides the following functions:
Routing and forwarding of data packets
Encryption and authentication
Session management
Mobility management
Logical link management
Generation and output of call detail records (CDRs)
1.2.2 GGSN The GGSN is also a functional entity that provides packet data services. It routes and encapsulates packet data between the GPRS/UMTS network and an external PDN. The GGSN provides the following functions:
Interface to an external PDN The GGSN serves as a gateway for an MS to access the external PDN. For the external network, the GGSN serves as a router for all equipment in the GPRS/UMTS network.
GPRS/UMTS session management The GGSN sets up a connection between an MS and the external PDN.
Data routing and forwarding The GGSN receives data from the MS and then forwards the data to the external PDN. It also receives data from the external PDN and selects a transport channel in the GPRS/UMTS network based on the destination address to forward the data to the SGSN.
FA functions To support mobile Internet Protocol (IP) services, the GGSN is embedded with FA functions. In this case, the GGSN/FA serves as a gateway of the GPRS/UMTS network and an FA of the network visited by the MS.
Charging for postpaid services The GGSN generates and outputs CDRs based on the usage of the external network by the subscribers.
Call control and service switching functions for prepaid services For prepaid services, the GGSN serves as a service switching point (SSP) that connects a mobile network and an intelligent network.
1.2.3 HA The HA is an entity that is used to support mobile IP access. It is an enhanced router that also maintains the current location information of the MSs. The HA has the following function:
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Sending broadcast messages to the MSs so that the MSs know if they are on the home network.
Handling and replying the registration requests from an MS. Generating mobility binding records (MBRs) between the MS home address and care-of address.
Agency and forwarding: The HA reports the availability of network prefixes for the MS home address so that the packets for the MS home address can be routed to the home network. After encapsulating the packets, the HA tunnels them to the GGSN/FA, and then the GGSN/FA finally forwards the packets to the MS.
1.2.4 CG The CG is a new device added to the GPRS/UMTS network. It collects, consolidates, and preprocesses CDRs generated by the SGSN or the GGSN. It provides an interface to the billing center. The CDRs are generated by several network entities when a GPRS or UMTS subscriber visits the Internet. Each entity may generate several CDRs. The CG is used to reduce the work load of the billing center by consolidating and preprocessing the CDRs before sending them to the billing center. With the CG in the network, the SGSN or the GGSN need not provide the charging interface to the billing center.
1.2.5 AAA Server The AAA server carries out authentication, authorization and accounting according to the Remote Authentication Dial-In User Service (RADIUS) protocol. The AAA server is not specific to the GPRS/UMTS system.
1.2.6 DNS Server There are two types of DNS server in a GPRS/UMTS network. The first is the DNS between the GGSN and the external PDN. As an ordinary DNS on the Internet, this DNS resolves the domain name of the external PDN. The second is the DNS on the GPRS/UMTS CN. The main functions of the DNS server include the following:
Resolves the GGSN IP address from the access point name (APN) to set up a connection between the GGSN and the MS when the MS accesses the external PDN.
Resolves the SGSN IP address from the old routing area code during the inter-SGSN routing area update.
Resolves the SGSN IP address from the new radio network controller (RNC) identity (ID) during RNC relocation.
The DNS server is not specific to the GPRS/UMTS system.
1.2.7 BG The BG is a router. In addition to security functions, it provides a routing function between the SGSN and the GGSN in different PLMNs. The BG is not specific to the GPRS/UMTS system.
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The FA and the HA are mandatory for mobile IP access. If the mobile IP access function is not required, the FA and the HA are not required.
1.3 Overview of the SGSN9810 The SGSN9810 can be used in a GPRS and a UMTS network. It supports up to 3 million subscribers attached to the network at the same time. Figure 1-2 shows the SGSN9810 appearance. Figure 1-2 SGSN9810 appearance
The SGSN9810 provides a wide range of services, functions, protocol interfaces, and physical interfaces. Built on the mature platform of Huawei products, it is reliable and easy to operate.
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The main functions of the SGSN9810 are listed as follows:
IP bearer services
Mobility management
Security management
Session management
Charging
Quality of service (QoS) and flow management
Static and dynamic routing
Simple network management protocol (SNMP) support
Optional functions include:
Point-to-Point Protocol(PPP) bearer services
Short message service (SMS)
Customized applications for mobile network enhanced logic (CAMEL) 3 intelligent services
Location service (LCS)
Internet protocol security extensions (IPSec) function
Lawful interception
2 Mbit/s signaling link
Multiple signaling points
Network time protocol (NTP)
Multiple HPLMNs
Iu-FLEX
Mobile virtual network operator (MVNO)
Network assisted cell change (NACC)
IP multimedia subsystem (IMS) bearing
IPv6
RAN sharing in connected mode
UESBI-Iu
Enhanced data rates for GSM evolution (EDGE)
High speed downlink packet access (HSDPA)
Differential service
Handover strategy control
Gb over IP
Signaling transport (SIGTRAN) support
SGSN N+1 backup
One Tunnel
Multi-SIM
APN error correction
The following features are added in the SGSN9810 V800R009 version:
Supporting boards of 750C series
Enhanced multimedia broadcast and multicast service (MBMS)
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Network share in the gateway core network (GWCN)
Security solution
Security Socket Layer (SSL)
Bidirectional forwarding detection (BFD)
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Key Benefits
The SGSN9810 is a competitive SGSN product offered by Huawei. It has multiple features and functions.
2.1 Large Capacity and High Integration If the boards of 750B series are used, the SGSN9810 can support a maximum of 2 million 2.5G and 3G attached subscribes concurrently. A fully configured SGSN9810 system requires five cabinets for a 2.5G network or three cabinets for a 3G network. If the boards of 750C series are used, the SGSN9810 can support a maximum of 3 million 2.5G and 3G attached subscribes concurrently. Only two cabinets are required for configuration of 2 million 2.5G or 3G subscribers, whereas three cabinets are required for configuration of 3 million subscribers.
2.2 High-Speed Hardware Forwarding The user plane data of the SGSN9810 is forwarded using hardware. This improves the processing efficiency and integration of the system. The hardware supports the traffic at the rate of 900 Mbit/s in a 2.5G system or the traffic at the rate of 10 Gbit/s in a 3G system.
2.3 Supporting Boards of 750C Series The SGSN9810 supports the boards of 750C series and thus the system performance and specification are greatly improved. As a result, the SGSN can meet the present and future performance requirements. Table 2-1 lists the hardware comparison between the 750C series and the 750B series.
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Table 2-1 Hardware comparison Hardware
750C
750B
CPU
750GX(clock frequency 1GHz)
750(clock frequency 500MHz)
Memory
1GB
512MB
FLASH
32M
16M
The maximum number of subscribers supported by the SGSN increases to 3 million. The number of cabinets for 2 million 2.5G subscribers decreases from five to two and that for 3G subscribers decreases from three to two.
2.4 Standard Protocol Interfaces The SGSN9810 supports a variety of 3rd Generation Partnership Project (3GPP) protocol interfaces to connect to the equipment from different vendors. This makes network deployment easy for operators. Figure 2-1 shows the protocol interfaces supported by the SGSN9810. Figure 2-1 Protocol interfaces supported by the SGSN9810 SMS-GMSC SMS-IWMSC
SM- SC CAMEL GSMSCF
GLMC Lg
MSC/VLR
Gd HLR
Ge
Gs
Gr
Gc Gi
TE
MT
UTRAN
Iu
MT
SGSN
BSS
TE
Gn
Gb TE
PDN
GGSN
SGSN
Ga Gn
Ga
Gp CGF GGSN
Gf
Billing System
EIR
Other PLMN
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2.5 Abundant Physical Interfaces The SGSN9810 provides the following physical interfaces to adapt different networks:
Gn, Gp, Ga, Iu-CS, and Iu-PS interfaces: STM-1, STM-4, 10 Mbit/s, 100 Mbit/s, and 1,000 Mbit/s Ethernet interfaces
Gb, Gd, Ge, Gf, Gr, Gs, and Lg interfaces: E1, T1, STM-1, STM-4, 10 Mbit/s, 100 Mbit/s, and 1,000 Mbit/s Ethernet interfaces
The 1,000 Mbit/s Ethernet interfaces support both optical ports and electrical ports.
2.6 Rich Services and Functions The SGSN9810 provides a wide range of services and functions. The basic functions include:
IP bearer services
Mobility management
Security management
Session management
Charging
Quality of service (QoS) and flow management
Static and dynamic routing
Simple network management protocol (SNMP) support
Optional functions include:
Point-to-Point Protocol(PPP) bearer services
Short message service (SMS)
Customized applications for mobile network enhanced logic (CAMEL) 3 intelligent services
Location service (LCS)
Internet protocol security extensions (IPSec) function
Lawful interception
2 Mbit/s signaling link
Multiple signaling points
Network time protocol (NTP)
Multiple HPLMNs
Iu-FLEX
Mobile virtual network operator (MVNO)
Network assisted cell change (NACC)
IP multimedia subsystem (IMS) bearing
IPv6
RAN sharing in connected mode
UESBI-Iu
Enhanced data rates for GSM evolution (EDGE)
High speed downlink packet access (HSDPA)
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Differential service
Handover strategy control
Gb over IP
Signaling transport (SIGTRAN) support
Supporting boards of 750C series
Enhanced multimedia broadcast and multicast service (MBMS)
Network share in the gateway core network (GWCN)
Security solution
Security Socket Layer (SSL)
Bidirectional forwarding detection (BFD)
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2.7 Accurate Clock System A clock synchronization system is required when the SGSN9810 uses the E1/T1 interface and the STM-1 or STM-4 optical interface to interconnect with other devices. The clock system of the SGSN9810, using the advanced digital phase-locked loop and reliable software phase-locked technology, has the following features:
It provides stratrum-2 (A and B types) and stratum-3 clocks.
The stratum-2 and stratum-3 clocks can be flexibly configured through terminals.
It provides multiple input reference signals, which include 2.048 MHz and 2.048 Mbit/s.
It provides powerful software functions, including display, alarm, O&M functions. The operators can conveniently control the phase-locked method and the source reference of the clock through the maintenance console.
It has powerful phase-locked capability and adapts to all kinds of clock transmission. In case that the clock reference has fault, the clock synchronization system of the SGSN9810 can work in free running mode and keep synchronization.
2.8 Easy Operation and Maintenance The operation and maintenance (O&M) system of the SGSN9810 has the following features:
Flexible O&M methods The O&M system can be flexibly built according to the network structure and customer requirements. Multiple maintenance interfaces are supported, including the interfaces to the local maintenance terminal (LMT), the Huawei centralized network management system iManager M2000, and the Simple Network Management Protocol (SNMP) based on the network management system. Through the Common Object Request Broker Architecture (CORBA) interface provided by the iManager M2000, more network management requirements can be fulfilled.
Friendly user interfaces The SGSN9810 provides O&M interfaces that combines the merits of both man-machine language (MML) and graphic user interface (GUI).
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The SGSN9810 provides functions to trace the messages of designated subscribers and the signals on the protocol interfaces such as the Iu, Gb, Gs, and Gr. The SGSN9810 also provides message explanation and filtering.
Software patching in function level Through online software patching, software errors can be solved without interrupting services. The SGSN9810 also supports remote patching and version fallback.
2.9 High Reliability The SGSN9810 is highly reliable because of the following features:
Backup of important data The SGSN9810 automatically backs up important data, such as the configuration data, performance data, and operation logs.
Operation security management Different management privileges are assigned to different users. During the user login, the SGSN9810 checks the user identity. After the user login, the SGSN9810 maintains the complete operation to ensure system security.
CG redirection and bill buffering When the active CG or the link to the active CG fails, the SGSN9810 sends the bills to the standby CG. If the standby CG is also faulty, the SGSN9810 stores the bills in its buffer.
Hardware redundancy design All critical boards are configured in the 1+1 backup or N+1 redundancy to ensure the high reliability of the system.
Fault Avoidance The SGSN9810 provides protection mechanisms to avoid the following system faults:
−
System power off
−
Maloperation on system power switch
−
Lightning surge on the system power
−
High voltage and low voltage
−
Short circuit of power supply
−
Lightning surge on E1/T1 links
−
Current surge and high voltage on the power supply and interfaces
System overload control In the case of center processing unit (CPU) overload or resource congestion, the SGSN9810 adjusts the traffic smoothly to avoid system down.
Board locking and system shutdown This function ensures that a service can slowly exit from a board or the system if required without interrupting other services.
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System Structure
The system structure of the SGSN9810 includes hardware structure, software structure, and logical structure.
3.1 Hardware Configuration The SGSN9810 hardware consists of the cabinet, subrack, and board.
Cabinet The SGSN9810 uses Huawei's N68-22 cabinet. This cabinet is a standard 19-inch one and is in compliance with the IEC297. The SGSN9810 requires 1~6 cabinets.
Subrack The SGSN9810 uses the standard 19-inch subrack, which is also called the PSM subrack. A maximum of four PSM subracks can be configured in each cabinet. Each PSM subrack contains 21 slots. Boards are inserted in front and rear of the backplane. According to the board configuration, the PSM subrack is classified into three types, namely, switching subrack, basic subrack and extension subrack.
Board According to the position, the boards of the SGSN9810 are classified into the front card, back card, and pinch board. The number of boards depends on the capacity of the system.
3.1.1 Cabinet Configuration Figure 3-1 shows an example of the cabinet configuration of the SGSN9810.
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Figure 3-1 Hardware configuration of the SGSN9810 Power Distribution Box
U F C U
U F C U
U F C U
U F C U
U F C U
U F C U
U R C U
U R C U
U C D R
U G T P
U G T P
U A L U
U P W R
U P W R
U U U U S G G G P B B B U I I I
U G B I
U A L U
U P W R
U P W R
U A L U
U P W R
U P W R
U U U L L A I I L P P U
U P W R
U P W R
U C D R
U G F U
U G F U
PSM Subrack Air Deflector
U U U U U I I S S S C C P P P P P U U U
U S P U
U R C U
U R C U
U S P U
PSM Subrack Air Deflector
U U U U U G G G G S B B B B P I I I I U
U S P U
U R C U
U R C U
U S P U
U U U U S G G G P B B B U I I I
PSM Subrack Air Deflector
U U U U U G G G G S B B B B P I I I I U
U S P U
U R C U
U R C U
U O M U
U O M U
U G T P
U G T P
PSM Subrack Dummy Panel
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3.1.2 Switching Subrack The switching subrack refers to the PSM subrack that is configured with the UFCU boards. Only one switching subrack is required. The fundamental function of the switching subrack is to forward data among the PSM subracks. Figure 3-2 shows the boards in the switching subrack. Figure 3-2 Boards in the switching subrack
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In Figure 3-2, the boards in the upper half of the subrack are inserted from the rear, and the boards in the lower half are inserted from the front.
Table 3-1 briefs the functions of the boards in the switching subrack. Table 3-1 Functions of the boards in the switching subrack Board
Function
Subrack control unit (URCU)
Bus mediation
Board configuration
Maintains boards
Controls the PSM subrack
PSM back interface unit (UBIU)
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Provides optical ports, network ports, and serial ports for the URCU.
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Board
Function
Auxiliary control unit (UACU)
Works with the URCU board to control the two buses in the PSM subrack.
Controls hot swap of the service processing boards in the PSM subrack.
Controls the switchover of URCU boards.
Monitors the power module of the PSM subrack.
Monitors back board status.
Monitors subrack temperature.
PSM alarm unit (UALU)
PSM power module (UPWR)
Provides power supply for the PSM subrack.
Frame connect unit (UFCU)
Forwards service subrack data.
Packet interface unit (UPIU)
Receives and forwards Asynchronous Transfer Mode (ATM) data and Ethernet link data.
GTP forwarding unit (UGFU)
Forwards GPRS Tunneling Protocol (GTP) data.
Charging detail record unit (UCDR)
Collects, encodes, and sends CDRs, and stores CDRs in the buffer.
Back storage unit (UBSU)
Provides external interfaces and a hard disk for the UCDR.
GTP processing unit (UGTP)
Forwards GPRS tunneling protocol for control plane (GTP-C) signaling messages and implements the charging function of GPRS tunneling protocol for user plane(GTP-U) data For NTP, DNS client and IPSec functions
3.1.3 Basic Subrack The basic subrack refers to the PSM subrack that is configured with the UOMU boards. Only one basic subrack is required. The fundamental function of the basic subrack is to provide operation and maintenance to the system, including operator management, configuration management, alarm management, tracing management, and performance measurement. Figure 3-3 to Figure 3-4 show the boards in the basic subrack for 2.5G network and 3G network.
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Figure 3-3 Boards in the basic subrack (2.5G network)
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Figure 3-4 Boards in the basic subrack
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Table 3-2 briefs the functions of the boards in the basic subrack.
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Table 3-2 Functions of the boards in the basic subrack Board
Function
Clock unit (UCKI)
Provides operation clock for the SGSN9810
Packet service signal processing unit (USPU)
For application layer protocols such as Session Management (SM), Mobility Management (MM), and Customized Applications for Mobile network Enhanced Logic (CAMEL) Processes Signaling System No.7 (SS7) L3 messages
Gb interface unit (UGBI)
For Gb interface protocols
Iu_PS control processing unit (UICP)
For Iu-PS control plane protocols
Packet service O&M unit (UOMU)
For the operation and maintenance functions of the SGSN9810
PSM flashdisk storage unit (UFSU)
Provides external interfaces and a hard disk for the UOMU
E1 processing interface unit (UEPI)
Provides external E1 interfaces for the Packet Service Signal Processing Unit (USPU) or Gb Interface Unit (UGBI)
T1 processing interface unit (UTPI)
Provides external T1 interfaces for the USPU or UGBI
LAN switch card (ULAN)
Serves as a local area network (LAN) switch to provide a connection between the UOMU and URCU
SIGTRAN process unit (USIG)
For the MTP3 User Adaptation Layer (M3UA) and Stream Control Transmission Protocol (SCTP) of the SIGTRAN
Lawful interception processing unit (ULIP)
Provides the following interfaces for lawful interception:
Lawful Interception Enhanced Processing Unit(ULEP)
The interfaces for receiving interception requests
The interfaces for collecting and transmitting interception messages
For Lawful Interception Enhanced Processing Unit
3.1.4 Extended Subrack The extended subracks process services. An extended subrack can be configured to process 2.5G services, 3G services, or both. Figure 3-5 shows the boards in a extended subrack for both 2.5G and 3G services. For the description of these boards, see Table 3-2.
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Figure 3-5 Boards in the extended subrack (2.5/3G)
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3.2 Software Structure The SGSN9810 is a distributed system where functions are distributed in and implemented by different boards. Each board has its own software that consists of a platform module and function-specific modules. Figure 3-6 shows the structure of the SGSN9810 software.
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Figure 3-6 Structure of the SGSN9810 software
USPU
UCDR O&M sub-system
ULIP
UGTP
UICP
UGBI
Device management sub-system
Service feature plane
UGFU
Database management subsystem
UFCU
Data forwarding plane
System management plane
Platform management sub-system (OS and DOPRA) Data service plane
The data service plane consists of a platform management subsystem, that is, the operating system (OS) and the Distributed Object-oriented Programmable Real-time Architecture (DOPRA). This plane is the basis of other software modules.
The system management plane manages the whole SGSN9810 system. It consists of three subsystems: −
O&M
−
Device management
−
Database management
The system management plane and the data service plane are the basic modules in each board software.
The data forwarding plane consists of the UGFU and UFCU. It carries out the switching, routing, and forwarding of ATM and IP packets.
The service plane processes services. It consists of the USPU, UCDR, ULIP, UGBI, UGTP, and UICP.
3.3 Logical Structure The SGSN9810 has twelve logical functional subsystems, as shown in Figure 3-7.
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Figure 3-7 Logical structure of the SGSN9810
ATM RNC GGSN
Signaling processing subsystem
PS transfer subsystem
IP
E1/T1 HLR
DNS NTP
Gb interface processing subsystem
PCU
BITS
Switching subsystem
Operation and maintenance subsystem
Clock subsystem
Iu interface control plane processing subsystem
GTP control plane processing subsystem
Charging subsystem
IP
LMT M2000
Lawful interception subsystem
This section briefs the functions of these subsystems and the hardware that implements the functions.
3.3.2 Switching Subsystem Function: Packets switching and interconnection between subracks Hardware: URCU, UPIU, and UFCU
3.3.3 PS Transfer Subsystem Function: routing and forwarding of GTP user data; Gn/Gp external interfaces Hardware: UGFU and UPIU
3.3.4 Gb Interface Processing Subsystem Function: implementing L1, Network Service (NS) and Base Station Subsystem GPRS Protocol (BSSGP) layer protocols of the Gb interface Hardware: UGBI and E1 processing interface unit (UEPI) or T1 processing interface unit (UTPI)
The UEPI or UTPI is not required when the Gb over IP function is enabled.
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3.3.5 Signaling Processing Subsystem Function: implementing L1, L2, and L3 of the Message Transfer Part (MTP), SIGTRAN, Signaling Connection and Control Part (SCCP), Mobile Application Part (MAP), MM, SM, CAMEL, and Location Service (LCS) protocols. Hardware: USPU, SIGTRAN process unit (USIG), and UEPI/UTPI
3.3.6 Lawful Interception Subsystem Function: X1-1/X2/X3 interfaces, collection and transmission of lawful interception data Hardware: ULIP and ULEP
3.3.7 Charging Subsystem Function: collection, storage, coding, and transmission or CDR data Hardware: UCDR
3.3.8 Iu Interface Control Plane Processing Subsystem Function: implementing the control plane Signaling ATM Adaptation Layer (SAAL), MTP3B, SCCP, and Radio Access Network Application Part (RANAP) protocols of the Iu interface Hardware: UICP
3.3.9 GTP Control Plane Processing Subsystem Function: implementing the GTP-C protocol and IPSec encryption of GTP-C signaling messages Hardware: UGTP
3.3.10 Operation and Maintenance Subsystem Function: external O&M interfaces, system O&M, configuration management, performance management, alarm management, and operation logs Hardware: UOMU and Flash Storage Unit (UFSU)
3.3.11 Clock Subsystem Function: providing stratum-2 or stratum-3 clock (secondary clock) for the system Hardware: clock unit (UCKI)
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Services and Functions
The SGSN9810 offers abundant services and functions, and meets the requirements of multiple networks and operations.
4.1 Services The SGSN9810 provides a full range of services to meet the demands of various subscribers. This section introduces the following services:
IP/PPP bearer services
Short message services (SMS)
Location services
CAMEL Phase 3 services
Lawful interception
4.1.1 IP/PPP Bearer Services The GPRS/UMTS network supports protocols such as the IPv4, IPv6, and Point-to-Point Protocol (PPP). The IP/PPP packets can travel transparently on the GPRS/UMTS network. Subscribers can use various IP and PPP applications, such as web browsing, File Transfer Protocol (FTP), and Virtual Private Network (VPN), through the GPRS/UMTS network. Figure 4-1 shows the structure of the protocol stacks that provide IP and PPP bearer services in a 3G network.
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Figure 4-1 IP/PPP bearer protocols (3G) Application E.g., IP,PPP
E.g., IP,PPP Relay
Relay
GTP-U PDCP
PDCP
GTP-U
GTP-U
RLC
RLC
UDP/IP
UDP/IP
MAC
MAC
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L1
L1 MS
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UDP/IP
L2
L2
L2 L1 Iu-PS
Uu
GTP-U
L1
3G-SGSN
UTRAN
L1 Gn
3G-GGSN
Gi
Figure 4-2 shows the structure of the protocol stacks that provide IP and PPP bearer services in a 2.5 network.
Figure 4-2 IP/PPP bearer protocols (2.5G) Application IP
IP Relay SNDCP GTP-U
SNDCP LLC
LLC
RLC MAC
UDP
Relay RLC BSSGP
BSSGP
Network Service GSM RF L1bis
Network Service L1bis
MAC
GSM RF MS
GTP-U
Um
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SGSN
UDP
IP
IP
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Gi GGSN
4.1.2 Short Message Services Short message services (SMS) include normal SMS and enhanced SMS.
Normal SMS allows for the messages that contain up to 160 bytes (including control bytes).
Enhanced SMS allows for formats in a message in addition to texts. These formats may include objects such as animations and images. A short message can contain more than one object.
SMS consists of two types of basic service:
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mobile terminated short message (SM-MT)
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SM-MT is the capability that enables the GSM/UMTS system to deliver the short messages submitted by the short message center (SMC) to the specified MS. At the same time, result (success or failure) of the message delivery is provided. In the case of delivery failure, a repeat strategy is implemented.
mobile originated short message (SM-MO) SM-MO is the capability that enables the GSM/UMTS system, with the help of the SMC, to forward the short messages submitted by an MS to the short message entity (SME). At the same time, result (success or failure) of the message submission is provided.
Figure 4-3 shows the basic network structure of the SMS. Figure 4-3 Basic network structure of the SMS
NodeB
RNC
MSC No.7
SMC BTS
BSC/PCU
SGSN
The GPRS-attached MSs or the GPRS-attached but international mobile subscriber identity (IMSI) -unattached MSs submit and receive short messages through the PS domain. The GPRS-attached and IMSI-attached MSs submit and receive short messages through either the PS domain or the circuit switching (CS) domain. If the messages are submitted through the CS domain, the SGSN can be used for paging.
4.1.3 Location Services The LCS enables the GPRS/UMTS network to locate an MS in the network and provide the geographic location of the MS after data conversion and calculation. The location data can be applied internally or externally.
For internal purposes, it can be used by the operator to fulfill certain requirements such as location-based charging.
For external purposes, it can be used by the network to provide various location-based services such as on-demand services, customized messages, and customized services.
Figure 4-4 shows the network of the LCS.
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Figure 4-4 Network of the LCS 2GMSC
A
gsmSCF GERAN Gb Um
Lg
Proprietary
2GSGSN
OSA SCS
Lc Lg
Proprietary
Iu
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Iu Uu
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Iu
MSC server
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LIF-MLP Lg
UTRAN
Le
OSA API
Lh
HSS
The LCS network includes the following major entities:
LCS client The LCS client originates location requests. Corresponding to the application of LCS, the LCS client includes the internal LCS client and the external LCS client.
GMLC The Gateway mobile location center (GMLC) provides an path for the LCS client to access the public land mobile network (PLMN). After receiving the location request from the LCS client, the GMLC requests routing data from the home location register (HLR) or the home subscriber server (HSS). At the same time, the GMLC forwards the request to the visited mobile switching center (VMSC), SGSN, or MSC server after authentication. The location result is also forwarded through the GMLC.
MSC, MSC server, and SGSN These entities connect to the GMLC through the Lg interface. They receive, process, and respond to the location request.
4.1.4 CAMEL Phase 3 Services The CAMEL enables operators to provide subscribers special services such as the prepaid service. Figure 4-5 shows how the SGSN supports CAMEL Phase 3 services in a GPRS/UMTS network.
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Figure 4-5 SGSN support to CAMEL Phase 3 services Home Network
HLR
gsmSCF
MAP
CAP
gprsSSF SGSN
Interrogating Network
MS
Visiting Network Home/Interrogating/Visiting Network
As shown in the figure, the SGSN integrates the GPRS service switching function (gprsSSF) and provide CAMEL Phase 3 services under the control of the GSM service control function (gsmSCF).
4.1.5 Lawful Interception The lawful interception is a capability of the mobile network to provide the content of communication (CC) of MSs and intercept related information (IRI) to a law enforcement agency (LEA). Figure 4-6 shows the procedure of lawful interception. Figure 4-6 Procedure of lawful interception Intercept request
Intercept reques
X1-1
LEA
Network node
ADMF X2
DF2
IRI
X3
CC
DF3
The procedure for lawful interception is as follows: 1.
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The LEA sends an intercept request to the administration function (ADMF) entity.
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2.
The ADMF forwards the request to the network node.
3.
The network node starts intercepting the CC of the target subscriber.
4.
The network node forwards the IRI and CC of the target subscriber to the LEA through the delivery function (DF).
As shown in Figure 4-6, the logical entities relating to the interception in a mobile network include the network nodes (SGSN and GGSN), ADMF, and DF. The ADMF controls the interception while the DF collects and forwards the IRI and the CC. Relevant interfaces include the X1-1 interface, X2 interface, and X3 interface.
X1-1 interface is between the ADMF and the network node. It transfers interception-related management messages from the ADMF to the network node.
X2 interface is between the DF2 and the network node. It transfers the IRI.
X3 interface is between the DF3 and the network node. It transfers the CC.
4.2 Functions The SGSN9810 provides powerful functions to meet the requirements of network operators. This section introduces the following functions:
Mobility management
Session management
Routing
IPv6 support
IPSec and logical link control (LLC) encryption
Charging
QoS
Iu-FLEX/Gb-FLEX
RAN sharing in connected state
MVNO
UESBI-Iu
Multi-SPs and 2 Mbit/s signaling link
NTP client functions
Network assisted cell change (NACC)
SIGTRAN support
Gb over IP
Differential services
Handover strategy control
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4.2.1 Mobility Management The MM function is used to control an MS access to the GPRS/UMTS network and trace the location of the MS, such as the routing area (RA) and SGSN information of the MS. The MM function is fulfilled mainly by attach, detach, and route updating procedures. It ensures that the location of the MS is updated while the MS is moving, such as the updating of the current SGSN information in the HLR.
4.2.2 Session Management The SM carries out Packet Data Protocol (PDP) context management. The PDP context is a group of messages related to the PDP. The network elements, such as the MS, SGSN, and GGSN, send and manage the PDP data based on the PDP context. Session management includes PDP context activation, modification, and deactivation. Before the MS transmits data, it must activate the PDP context. During the data transfer, the PDP context can be modified based on the requirement of the QoS. After data transfer, the PDP context must be deactivated to release network resources.
4.2.3 Routing The SGSN9810 supports various routing protocols to ensure the flexible networking using the Gn/Gp interface.
Static Routing Static routes are manually configured by the administrator. Users can configure static routes to set up a connected network. In a simple network, static routes can be used to ensure the stable operation of the router. Well configured static routes can improve the performance of the network and ensure the bandwidth for critical applications. When the network is faulty, the static route cannot adjust itself and requires reconfiguration.
OSPF The open shortest path first (OSPF) is an interior gateway protocol (IGP) developed by the internet engineering task force (IETF). The OSPF is implemented based on link status. The OSPF has the following features:
Large scope The OSPF can be used for the networks of various sizes and support up to hundreds of routers.
Fast convergence After the network topology is changed, an update message is sent at once to synchronize the data in the autonomous system.
Loop free The OSPF uses the shortest path algorithm to determine a route based on the link status. The algorithm ensures that the route is loop free.
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Area division
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The network of the autonomous system can be divided into several areas so that the network is easy to manage. The route information transferred between the areas is abstracted, so the required bandwidth is further reduced.
Equivalent route Multiple equivalent routes to the same destination are supported.
Hierarchical routes Routes are classified into four categories. They are (from high to low priority) intra-area routes, inter-area routes, class-1 external routes, and class-2 external routes.
RIP II The routing information protocol (RIP) is a simple IGP that is used in small networks. The RIP is widely used in networks thanks to the following features:
Easy to implement
Little protocol overhead which makes almost no impact on the network performance
Easy to configure and maintain compared with the OSPF and intermediate system-to-intermediate system (IS-IS) intra-domain routing information exchange protocol
4.2.4 IPv6 Support The rapid development of Internet services requires more and more IP addresses, which are beyond the capability of the IPv4 protocol. As a result, the IPv6 is developed to address this problem. Compared with the IPv4, the IPv6 boasts of the following advantages:
Extended IP addresses IP addresses are extended from 32 bits in the IPv4 to 128 bits in the IPv6, indicating that the address resources are abundant. This address structure also improves routing efficiency.
Simplified packet header format The packet header is simplified to minimize the processing by routers; thus it improves routing efficiency.
Enhanced support for extension and option capability The IPv6 satisfies additional requirements without affecting the routing of normal packets or special packets.
Flow identity The flow identity is used to improve the processing of packet flows, especially real-time applications.
Identity verification and security Enhanced identity verification and security measures make IPv6 especially suitable for sensitive commercial information.
The data plane and the signaling plane of the SGSN9810 Gn/Gp interface supports both IPv4 and IPv6 addresses. Operators can choose one of the following four operational modes:
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Preferring IPv6 addresses
Supporting only IPv4 addresses
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4.2.5 IPSec and LLC Encryption To ensure the security of data transfer, the SGSN9810 supports IPSec encryption for the signaling massages on the Gn/Gp interface and data encryption for the Gb interface messages.
IPSec The SGSN9810 encrypts the Gn/Gp signaling messages by using the IP Security (IPSec) protocols. The IPSec is a series of protocols developed by the IETF to ensure the security of the data that is transmitted on the Internet. Through encryption and data source verification on the IP layer, the privacy and integrity of data packets can be guaranteed when the packets are transferred on the Internet.
LLC Encryption In a 2.5G system, the encryption on the Logical Link Control (LLC) layer between the MS and SGSN is the traditional stream encryption using the GPRS-A5 algorithm. The data to be encrypted includes the information field and the authentication field carried by LLC frames.
4.2.6 Charging Figure 4-7 shows the GPRS/UMTS charging network. The SGSN and GGSN collect the charging information relating to radio network resource usage and CN resource usage by each MS. Then they generate CDRs and send them to the CG through the Ga interface. Figure 4-7 GPRS/UMTS charging network
SGSN
GGSN Gn
BTS
BSC/PCU Ga
NodeB
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The SGSN9810 can generate the following seven CDRs:
SGSN generated - CDR(S-CDR): records the information related to certain PDP contexts in the SGSN
Mobility management generated - CDR(M-CDR): records the mobility-related information
SGSN delivered short message mobile originated - CDR(S-SMO-CDR): records the information related to SM-MO services
SGSN delivered short message mobile terminated - CDR(S-SMT-CDR): records the information related to SM-MT services
Mobile terminated LCS CDR(LCS-MT-CDR): records the information related to mobile-terminated location services
Mobile originated LCS CDR(LCS-MO-CDR): records the information related to mobile-originated location services
Network induced LCS CDR(LCS-NI-CDR): records the information related to network-initiated location services
4.2.7 QoS The 3GPP R5 specifications define four classes of QoS, as described in Table 4-1. Table 4-1 UMTS QoS classes Traffic Class
Conversational Class
Streaming Class
Interactive Class
Background Class
Characteristics
Preserve time relation between entities of the stream
Preserve time relation between entities of the stream
Request response pattern
Destination does not expect the data within a certain time.
Video
Web browsing
Download or sending e-mails
Conversational pattern (high quality, low delay) Example of the application
Voice
The SGSN9810 support the four QoS classes by using the following mechanisms:
Access control When the subscriber activates the PDP context, the SGSN negotiates the QoS with the MS. If the negotiation fails, the SGSN denies the MS access.
QoS queue management The data packets are assigned to QoS queues based on the QoS class. The SGSN dispatch the queues using the class-based weighted fair queuing (CBWFQ) algorithm to decide the order of transmission.
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In case of congestion, the SGSN decides the discard criteria of packets by using the weighted random early detection (WRED) algorithm. This ensures the transmission reliability of the high-priority data.
Differentiated Services (DiffServ) DiffServ is an IP QoS model that is used in a backbone network to meet various service requirements. In the DiffServ system, the network node determines the per-hop behavior (PHB) according to the differentiated services code point (DSCP) in the IP header. The SGSN supports the following PHBs: expedited forwarding (EF), assured forwarding (AF), and best-effort (BE). It also supports the three discard priorities of the AF.
QoS mapping QoS mapping converts the QoS attributes of different bearer protocols. It includes the mapping between the 3GPP QoS and DSCP, between the DSCP and the ATM QoS, and between the R97/98 and the R99 QoS attributes.
CAR and Remarking If the actual data packet stream requires the QoS higher than the requested one, the SGSN handles the packets based on the committed access rate (CAR) and discard the extra packets. SGSN can also carry out a Remarking process to lower the QoS of the data packet.
4.2.8 Iu-FLEX/Gb-FLEX The Iu-FLEX/Gb-FLEX function allows one RAN or base station subsystem (BSS) to connect to several CN nodes in the same domain. The Iu-FLEX/Gb-FLEX function introduces the concept of pool areas. Similar to an MSC or SGSN service area, a pool area contains one or more RAN/BSS service areas, but it is served by multiple CN nodes (MSC or SGSN) at the same time. See Figure 4-8 for details.
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Figure 4-8 Example of pool area configuration MSC 3 MSC 2 MSC 1
MSC 6 MSC 5 MSC 4
MSC 7
CS poolarea 2
CS poolarea 1 RAN node Area 1
RAN node Area 5
RAN node Area 6
PS poolarea 1 SGSN 1 SGSN 2
RAN node
RAN node
RAN node Area 2
Area 3
Area 4
RAN node Area 7
RAN node Area 8
PS poolarea 2 SGSN 3 SGSN 4 SGSN 5
SGSN 6
The Iu-FLEX/Gb-FLEX function expands the service areas of each CN node and reduces the effort required for the inter-node update, handover, relocation, and HLR update. This function also improves system availability. If one CN node in the pool area is faulty, other nodes can provide services.
4.2.9 RAN Sharing in Connected State Figure 4-9 shows the scenario of RAN sharing in connected state. In this scenario, the networks of operator A and operator B together cover a large area in which an overlap area exists. The RANs of operator A and operator B are connected through the CNs, so the user equipment (UE) of operator B can operate in the network of operator A. In the overlap area, the UE of operator B must access the RAN of operator B rather than the network of operator A.
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Figure 4-9 RAN sharing between operators Core Network A
Core Network B
Radio Access Network A
Radio Access Network B
To solve the problem mentioned above, the R5 protocol introduces the concept of shared network area (SNA). An SNA corresponds to one or more location areas (Las) that control the UE access. The SNA is configured in the CN. The CN provides an SNA ID list that contains the SNAs that the UE can access. If the location area (LA) is in the SNA that the UE can access, the RAN allows the UE to access the network. Otherwise, it denies the UE.
4.2.10 MVNO A mobile virtual network operator (MVNO) uses the resources authorized by a mobile network operator (MNO) to provide services and maintain the authorized resources. The MVNO function enables more operators to invest on and share the network to lower the investment risk and maximize resource usage. The network resources authorized by the MNO can be the RAN, part of the CN, or the whole CN. Figure 4-10 shows the example of partial CN sharing. In the example, the MNO shares its SGSN with the MVNO, and the MVNO owns the GGSN, CG, and other network equipment.
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Figure 4-10 MVNO network MVNO CG
SGSN
GGSN
GGSN Internet
BTS
NodeB
BSC/PCU
RNC
MNO
CG
Billing Centre
4.2.11 UESBI-Iu The UEs may have potential standard or manufacture defects. The RAN needs UE-specific behavior information (UESBI) regarding 3GPP features to help the lower layer process the local 3GPP features. The UESBI corresponds to the following two sets of information:
UESBI-Uu: The messages are sent by the UE to the RAN through the messages defined by the Radio Resource Control (RCC) protocol.
UESBI-Iu: The message is obtained by the CN from the International Mobile Station Equipment Identity and Software Version number (IMEISV) of the UE. The CN then sends the messages to the RAN through the Iu interface.
Figure 4-11 shows the network structure of the UESBI-Iu.
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Figure 4-11 Network structure of the UESBI–Iu 1
Attach and IMEISV interrogation
2
IMEISV Storage
3 UESBI
MSC
IMEISV UE NodeB
SRNC
SGSN
When the UE accesses the VLR or SGSN, the IMEISV from the UE is saved in the VLR or SGSN. When an Iu connection (such as CS voice session and PS data transfer) is set up later, the IMEISV is read from the MM context of the VLR or SGSN to obtain the UESBI. The UESBI is then sent to the serving RNC (SRNC).
4.2.12 Multi-SPs and 2 Mbit/s Signaling Links Ever increasing equipment capacity boosts the signaling flow between signaling points. The 16 signaling links specified by the protocol are far from enough to fulfill actual networking requirements. To solve this problem, the SGSN9810 provides the multiple signaling points (multi-SPs) function and 2 Mbit/s signaling links.
Multi-SPs Function The SGSN9810 entity can be divided virtually into several logical signaling points. Thus the restriction of 16 signaling links between two signaling points is broken. As shown in Figure 4-12, from the aspect of other signaling points, the SGSN9810 contains multiple signaling points, and there are 16 links for each signaling point.
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Figure 4-12 Multiple signaling points supported by the SGSN9810 Link Set Link
SP
SP
Single SP
Link Set
Link
SP1 SP SP2
Multi SPs
Link Link Set
2 Mbit/s Signaling Links A 2 Mbit/s signaling link binds multiple timeslots into an E1/T1 link to increase the throughput of a link.
4.2.13 NTP Client Functions The network time protocol (NTP) is a TCP/IP protocol that is used to issue accurate time in the entire IP network. Its transmission is based on the UDP. The RFC1305 specifies the algorithm used by the NTP to ensure the accuracy of clock synchronization. Theoretically, the accuracy can be 1 ns. Figure 4-13 shows the synchronous networking mode of the NTP. The NTP time synchronization can be realized provided that the network from the device or the lower server to the upper server is available. The time accuracy offered by the NTP synchronous networking mode is of ms. This can be applied in alarm, log, and performance measurement.
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Figure 4-13 NTP synchronous networking mode Class 0
NTP Server Class 1
NTP Server
NTP Server
NTP Server
Class 2
NTP Server
NTP Client
NTP Server
NTP Client
The NTP services can be classified into three types when the NTP synchronous networking mode is used.
NTP server of the highest layer: It refers to the NTP server of stratum 0, which offers time synchronization service to the lower layer.
NTP server of the intermediate layer: Stratum 1 and stratum 2 obtain time from the time server of upper layer, and offer time synchronization to the lower layer.
NTP client: It only obtains time. Time synchronization service is not offered.
When the SGSN9810 is configured as the NTP client, it obtains time from the NTP server of upper layer and synchronizes time. Figure 4-14 shows the networking of the SGSN9810 synchronizing the NTP server. Figure 4-14 Networking of the SGSN9810 synchronizing the NTP server
IP Network SGSN9810
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4.2.14 Network-Assisted Cell Change When an MS initiates cell reselection between base station controllers (BSCs) during data transfer, the network assisted cell change (NACC) function is used to reduce the delay and improve the QoS. In most cases, service interruption can be controlled within 300 ms to 700 ms, while the normal service interruption is about one or two seconds. To assist fast cell reselection, the MS must know some information about the system of the target cell. If the target cell belongs to another BSC or RNC, the system information is transferred across the BSCs or RNCs. In this case, the system information is in the RAN-Information message and sent to the target BSC or RNC by the SGSN.
4.2.15 SIGTRAN Support The Signaling Transport (SIGTRAN) protocol stack is defined by the Internet Engineering Task Force (IETF) to enable the inter-working between SS7 and IP networks. The SIGTRAN enables an IP network to transfer the signals of a legacy switched circuit network (SCN). It supports the standard inter-layer primitive interfaces defined in the SCN signaling protocol model to ensure that SCN signaling messages can be used without any change. With the standard IP transport protocol as its lower layer, the SIGTRAN provides special functions to meet the requirements for SCN signaling transfer. Functionally, the SIGTRAN protocol stack is classified into the following two types:
General signaling transmission protocols This type of protocols fulfills the efficient and reliable transfer of SS7 signaling messages on an IP network. The Stream Control Transmission Protocol (SCTP) is now used for this purpose.
SS7 signaling adaptation protocols This protocols are designed to adapt the various signaling protocols used by the SCN. They include M2UA, M3UA, IUA, and V5UA.
Figure 4-15 shows the SIGTRAN protocol stack model. Figure 4-15 SIGTRAN protocol stack model
M3UA
M2UA
IUA
SUA
M2PA
V5UA
SCTP
IP
M3UA M2UA
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ISDN Q.921 User Adaptation Layer MTP2 Peer Adaptation Layer V5 User Adaptation Layer SCCP User Adaptation Layer Stream Control Transmission Protocol Internet Protocol
This manual introduces only the SCTP and M3UA used by the SGSN9810.
In the SGSN9810, the SIGTRAN protocols are applied on the Iu-PS interface signaling plane and the SS7 interface. The SGSN9810 can also use a signaling gateway (SG) to communicate with the signaling points that do not support SIGTRAN functions, Figure 4-16 shows how the SGSN9810, RNC, and HLR communicate on an IP network using the SIGTRAN protocols. Figure 4-16 Communication with the RNC and HLR on an IP network using the SIGTRAN protocols
SCCP
SCCP
MTP3
M3UA IP Network
MTP2
SCTP
MTP1
IP
HLR
SGSN
SCCP
MTP3
MTP3
M3UA
MTP2
SCTP
MTP1
IP
SS7 Network MTP2
MTP1
HLR
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4.2.16 Gb over IP On the Gb interface, the Network Service (NS) layer implements the following functions for the upper layer:
Service data unit (SDU) transfer between the SGSN9810 and the BSS
Network congestion indication
Status indication
Figure 4-17 shows the protocol stacks on the Gb interface. Figure 4-17 Protocol stacks on the Gb interface
LLC BSSGP
BSSGP
Network Service Control
Network Service Control
FR
IP
FR
IP
L1
L1
L1
L1
Gb BSS
SGSN
he 3GPP protocols specify that Sub-NS messages can be carried by a frame relay network or an IP network. The SGSN9810 version earlier than V800R006 supports frame relay network. In version V800R006, the Gb over IP feature is added to support Sub-NS message transfer over an IP network on the Gb interface. The end-to-end communication on the Gb interface between two remote networks is implemented through network service – virtual circuits (NS-VC). An NS-VC is a virtual path between two peer entities on the NS control layer. It is defined by a quadruple consisting of the SGSN IP address, SGSN UDP port number, BSS IP address, and BSS UDP port number, as shown in Figure 4-18.
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Figure 4-18 NSVC in the Gb over IP
SGSN
BSS
NSEI=2
NSEI=1 NSVC1(UDPA/IP1, UDPB/IP3) UDPA IPI
UDPA IP2
NSVC2(UDPA/IP1, UDPC/IP4)
UDPB IP3
NSVC3(UDPA/IP2, UDPB/IP3)
UDPC IP4
NSVC4(UDPA/IP2, UDPC/IP4)
4.2.17 Differential Services The differential service provides various access control strategies according to subscriber priorities and service levels. Subscribers are grouped into three classes according to their priorities:
High level subscribers
Normal subscribers
Low level subscribers
The service level depends on the following QoS parameters in the PDP context:
Traffic class
Guaranteed bit rate for downlink
Traffic handling priority
Operators offer different services to different subscribers through the following two methods:
Specify the threshold of system resource usage to restrict the attach and routing area update (RAU) operations of some subscribers.
Specify the threshold of PDP context resources to restrict certain services of some subscribers.
4.2.18 Handover Strategy Control The handover strategy control helps operators in distributing traffic and balancing load between 2G networks and 3G networks.
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This function is applicable to the 2G and 3G supportive terminals that are allowed to access these two types of network. When a terminal is in a 3G network, the handover strategies include:
Handover to 2G network recommended
Handover to 2G network not recommended
Stay in the 3G network
The handover strategy control information is sent as a cell to the RNC during radio access bearer (RAB) assignment and relocation procedures. If a terminal is in a 2G network, the handover strategies include:
Handover to 3G network recommended
Handover to 3G network not recommended
Stay in the 2G network
The handover strategy control information is sent as a cell to the BSS during the create-BSS-PFC procedure.
4.2.19 Enhanced MBMS The 3GPP protocol defines two MBMS operating modes, that is, broadcast mode and multicast mode. In MBMS broadcast mode, multimedia data, such as letters, audio frequency, video frequency, and pictures are sent from a data source to all the users in a broadcast serving area. Broadcast mode is a unidirectional and point-to-multipoint service in which multimedia data is transmitted from a single source entity to all the users in a broadcast serving area. Generally, broadcast service is free for reception terminals, and thus the operation such as activation or subscription is not required. The carriers, however, may charge some sponsors, such as advertisers, by broadcast service time or traffic volume. The MBMS broadcast mode is classified into two types: common broadcast mode and enhanced broadcast mode. The enhanced broadcast mode of MBMS can implement the partial multicast function under the broadcast mode. It can determine whether to use the PTP or PTM mode based on the number of MBMSs selected by the UEs in a cell. In addition, it supports conversion between PTP and PTM. The enhanced broadcast mode of MBMS simplifies the multiple operations under the MBMS multicast mode, and thus simplifies the function implementation of the system. In MBMS multicast mode, a network sends data to the cells in which users can receive multicast services are located. Compared with broadcast mode, multicast mode requires users to subscribe to related service before joining a multicast group. Users apply to join a multicast group through the multicast service activation procedure and to quit the group through the deactivation procedure. Generally, multicast services are charged. Figure 4-19shows the network topology of the MBMS service.
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Figure 4-19 Network topology of the MBMS service PDN (e. g. Internet ) Content Provider / Multicast Broadcast Source
HLR
OSA SCS
Gr Uu UE
Iu UTRAN
SGSN
Gn/Gp
Gmb GGSN TPF
BM - SC Gi
Content Provider / Multicast Broadcast Source
Iu / Gb Um UE
GERAN
The Gmb interface is a signaling interface added for the MBMS service. The broadcast multicast service center (BM-SC) is a new network element (NE) in the packet switched (PS) domain. The functions of various NEs are as follows: BM-SC
−
Informing the GGSN of the start time and end time of a session and specifying the session parameters, including QoS and MBMS service area.
−
Authorizing activation of a user for the GGSN.
−
Providing the Gmb protocol agent function. The BM-SC allows distributed physical entities to share one MBMS bearer service. The protocol agent shields the routes between the distributed entities and makes the entities transparent to the GGSN.
GGSN
−
As the entrance to IP multicast service, the GGSN initiates MBMS bearer establishment and release upon the BM-SC notification.
−
Receiving the IP data packets of MBMS service from the Gi interface and routing them to appropriate GTP tunnels.
−
Shielding the MBMS multicast source messages outside a public land mobile network (PLMN).
−
Collecting MBMS charging information
−
Performing flow billing charge (FBC)
SGSN
−
Receiving MBMS data from the GGSN and forwarding the data to the UTRAN
−
Establishing and releasing the Iu and Gn bearer used in the MBMS service
The SGSN9810 does not support the multicast mode. The SGSN of V800R009 does not provide the charging function for MBMS. Instead, the charging is implemented by the GGSN.
4.2.20 Network Share Network share is applicable to the following networks: multi-operator core network (MOCN) and gateway core network (GWCN). At present, the SGSN9810 supports network share only in the GWCN.
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The GWCN share refers to the share in the access network. In addition, partial core networks of each operator are also shared.Figure 4-20 shows the network configuration of the GWCN. Figure 4-20 Network configuration of the GWCN
.........
CN Operator A
CN Operator B
Shared MSC/SGSN
Shared MSC/SGSN
CN Operator C
.........
Shared MSC/SGSN
Iu
RNC
RNC
RNC
Radio Access Network Operator X
The GWCN share has the following features:
The network within the shared area (covering the RAN and partial CN) is set up by one operator. This network is shared to other operators.
The shared RAN needs to connect with only the shared CN, which is the same as in the common network.
The common CN needs to connect with the CNs of other operators.
The service requests of the UEs in the shared area are routed to the subscribed CN. The routing function is implemented by the devices (MSC and SGSN) in the common CN.
The differences between network share and mobile virtual network operator (MVNO) are as follows:
MVNO is not a feature stipulated by the 3GPP protocol. The SGSN does not need to attend to the other devices at the wireless network and core network sides. The MVNO feature is based on the mobile network operator (MVO), maybe one or multiple public land mobile networks (PLMNs), for the local SGSN. It is used to set up a virtual operator independent of the MVO by partitioning certain resources such as number of users and number of PDP contexts. The MVNO feature has no requirement on other NEs. It is a feature only possessed by the SGSN.
The network share feature implemented in the GWCN and MOCN is stipulated by the 3GPP protocol. Apart from the SGSN, the feature requires the support from the wireless network side and terminals. The MOCN and GWCN network modes cannot be enabled simultaneously.
4.2.21 Security Solution The security solution for the SGSN refers to the solution to antivirus and anti-GTP.
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The antivirus solution for the SGSN is as follows:
The SGSN can filter the uplink and downlink worm virus based on the configured worm characteristics, such as the specified destination IP address, specified destination UDP/TCP port, and ICMP type.
The SGSN can check the source IP addresses of the data packets transferred on the uplink user plane for UEs and thus prevent the Deny of Service (DoS) from attacking and the worm virus from spreading.
For the PDP context that carries virus traffic, the SGSN decelerates and deactivates the PDP context based on the configuration.
If the virus traffic carried by a PDP context disappears, the SGSN resumes the rate of this PDP context.
Virus alarms are exported by the call history record (CHR).
Figure 4-21shows the structure of the SGSN antivirus system. Figure 4-21 Structure of the SGSN antivirus system. SGSN User plane data Iu/Gb
Stream filtering and forwarding
Virus characteristic White list
User plane data Gn
Session managment
Adjusting air interface rate/ deactivation rate
Calling log/ alarm
The antivirus function requires the analysis of the payload protocol for the user planes packets. The SGSN processing capability on the user plane weakens if the antivirus function is enabled. If the antivirus function is not enabled, the SGSN processing capability on the user plane remains unchanged.
The GTP attack indicates that malicious users send the GTP packets in a certain quantity to the SGSN by using some characteristics of the GTP protocol. As a result, the services on the attacked SGSN are interfered and even disrupted. The solution to the GTP attack is as follows: The SGSN can identify various abnormal packets such as the illegal GTP version number, GTP packet in excessively short length, inconsistency between the current length and the actual length of the GTP packets, unknown message type, and a great number of repeated extension headers when receiving the GTP packets. Thus, the system stability and processing of the subsequent packets are not affected.
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4.2.22 Bidirectional Forwarding Detection (BFD) Bidirectional Forwarding Detection (BFD) is a uniform detection mechanism used in the entire network. It is used to rapidly detect and monitor the forwarding connection of the links or IP routes in the network. To improve the network performance, the adjacent systems should rapidly detect communication failure and then set up backup channels to restore communication. The following methods are applied to detect communication failure in the current network:
Detect the link hardware faults through the hardware detection signals, such as the SDH alarm.
If the hardware detection signals for detecting failure do not work, the Hello packet mechanism of the routing protocol is used instead. It takes a relatively long time for this mechanism to detect failure, usually, more than 1 s. If the rate of data reaches the Gbit/s level, mass of data is lost due to the long detection period.
The operation experience manifests that the ideal protection time for switchover should range from 50 ms to 500 ms for the multi-service IP bearer network. The BFD function supported by the SGSN realizes the network reliability. BFD has the following functions:
Providing bidirectional detection for links: The detection packets are simultaneously sent at both ends of the bidirectional links. Thus, the link status on the two directions is detected and the link fault detection is implemented at the ms level.
Based on the asynchronous detection mode: The asynchronous detection mode indicates that every system sends the BFD control packets within a negotiated period with each other. If a certain system does not reach the packets sent from its peer end within the detection period, you can infer that the session between the systems is Down.
Providing the dynamic modification function for BFD parameters: After a session is established, the relevant BFD parameters, such as the minimum sending interval, minimum receiving interval, enabling or disabling query mode, echo packet, and packet authentication, can be dynamically modified. The systems at both ends can adopt the new parameters by sending the relevant negotiated packets, but not affecting the current state of the session.
Providing the BFD detection for single-hop and multi-hop links. At present, the SGSN supports the BFD function only for static routes. Therefore, the network administrator must intervene in the case of network fault because the static routes do not possess the detection mechanism. If the BFD function is enables, the status of the IPv4 static routes in the public network can be detected through the BFD session. Thus, the route management system can determine whether the static routes are available based on the state of the BFD session.
4.2.23 One Tunnel The one tunnel feature indicates that the SGSN can directly set up a GTP-U tunnel between the RNC and the GGSN. Therefore, user plane data can be transferred without passing the SGSN. With the increasing development of 3G services and application of technologies, such as high speed packet access (HSPA), the WCDMA core packet network must improve the handling capability on user planes. In the original network, GTP-U tunnels are set up between the RNC and the SGSN and between the SGSN and the GGSN. That is, two tunnels are required. Therefore, the RNC, SGSN, and GGSN must simultaneously improve the handling capability on their user planes. This inevitably increases fund investment and operation cost for carriers.
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To reduce capital expenditure (CAPEX) and operation expenditure (OPEX) for carriers and to facilitate future network expansion, the 3GPP protocol puts forward the concept of one tunnel, that is, one GTP-U tunnel is set up between the RNC and the GGSN. In this way, user plane resources are saved and thus fund investment and operation cost paid by carriers is also reduced. In addition, the one tunnel feature optimizes the performance of the user planes of the WCDMA packet network. The one tunnel feature has the following advantages:
Reducing a majority of SGSN user plane resources and thus reducing CAPEX and OPEX for carriers
Shortening the user plane delay and thus enhancing customer satisfaction
Separating the controlling plane from the user plane for easy upgrade to the system architecture evolution (SAE) network
Supporting expansion of the user plane with upgrade of only the GGSN and the RNC instead of the SGSN to improve the network expansibility
4.2.24 SGSN N+1Backup The serving GPRS support node (SGSN) is a network element (NE) that provides packet data service. It forwards incoming and outgoing IP packets to the mobile stations (MSs) within its wide serving area. Therefore, it plays an important role in the GPRS mobile packet network. In the case of fatal disasters, such as human maloperation, equipment failure, and natural calamity, large-scale mobile packet service is disrupted and thus causes huge loss. To ensure that the mobile packet network operates securely and reliably, Huawei realizes remote disaster tolerance backup for the SGSN. That is, a backup SGSN is added for the SGSN running on the network. In normal cases, the active SGSN handles all signaling and services. If the active SGSN is faulty, the disaster-tolerance SGSN can undertake all the work and ensure proper operation of the packet network. Figure 4-22 Peer SGSN (N =2)
4.2.25 Multi SIM Multi Subscriber Identity Module (Multi-SIM) means that multiple (U)SIMs correspond to the same MSISDN and each SIM corresponds to different IMSI.
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The mobile user can insert multiple (U)SIMs into several terminals. For instance, one SIM is inserted into an MS and another SIM into a car phone. In addition, the subscriber can specify each (U)SIM terminal of the same MSISDN for specific services. The services include voice service, GPRS/UMTS packet data service, Email, and SMS/MMS. The services can be used simultaneously without mutual interference. The business and operation support system (BOSS) provides only one bill to a Multi-SIM user of the same MSISDN. The mobile user can check the bill according to the IMSI. Apart from the SGSN support, the Multi SIM feature requires the NE support and the system support. The following lists the required NE report and the system support:
MSC Server The MSC Server supports the processing of Multi SIM user's calling services in the CS domain.
HLR When an MS of a certain IMSI attaches to the SGSN, the HLR must insert the user data relevant to the IMSI into the SGSN.
GGSN The GGSN collects the charging information about a Multi SIM user.
SCP The SCP uniformly manages the credit line of a Multi SIM user.
BOSS BOSS charges a Multi SIM user and uniformly generates bills according to the MSISDN. The bill is not consolidated on the SGSN and the CG. The bill transmitted to BOSS contains the user's MSISDN and IMSI. The bill printed by BOSS contains the user's IMSI so that the user can check the bill of each MS according to the IMSI.
CG The protocol version of CG must ensure that the MSISDN and IMSI characters can be contained in the bill. This facilitates the uniform charging of the MSISDN.
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Operation and Maintenance
The SGSN9810 offers abundant and convenient O&M function. This reduces the difficulty of device maintenance and ensures the normal operation of the device.
5.1 O&M System Figure 5-1 shows the structure of the O&M system. Figure 5-1 O&M system of the SGSN9810 M2000
IP Network SGSN
LMT
SNMP Server
As shown in Figure 5-1, the SGSN9810 provides three O&M methods:
Local maintenance through the local O&M terminals: This method is applicable to original system installation and fault location.
Central maintenance through the iManager M2000: This is the main method for regular maintenance.
Reporting the maintenance information to the SNMP-based network management system through the SNMP interface: Only alarms and performance data are reported.
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5.2 Configuration Management Configuration management includes operations such as the addition, deletion, modification, and query of system data. The SGSN9810 provides two ways of data configuration:
Dynamic configuration: Data can be configured when the system is running.
Static configuration: The text data file (MML or TXT) is edited offline and the data takes effect when the system is reset.
5.3 Equipment Management Equipment management monitors, controls and tests system entities such as hardware components and links. The SGSN9810 provides the following equipment management features:
Status query The SGSN9810 allows operators to query the operational status of the system entities. The entities include boards, optical ports, E1 ports, SS7 links, Frame Relay (FR) links, Signaling ATM Adaptation Layer (SAAL) links, GTP path, Bear Channels (BCs), NS-VCs, destination signaling point, subsystems, Point To Point (PTP) BSSGP Virtual Connections (BVCs), and Special Interest Group (SIG) BVCs.
Status control The status control function allows for the following operations:
−
Board reset and switchover
−
Blocking, unblocking, and reset of optical ports, E1 ports, SS7 links, FR links, – SAAL links, GTP paths and BCs
−
Inhibiting and enabling of destination signaling points and subsystems.
Test function Testing is an effective way to locate faults. The SGSN9810 supports loopback tests on E1 ports and SAAL links, as well as GTP path tests.
5.4 Tracing Management The SGSN9810 provides interface tracing and subscriber tracing. It is a powerful tool for equipment maintenance. The interface tracing can trace messages on interfaces such as the Gb, Iu, Gn/Gp, Gs/Gd/Gr, and Ga. It can also trace messages based on the protocol layer such as SCCP, MTP3b, and SAAL. The subscriber tracing traces the messages of the specified IMSI or mobile station international ISDN number (MSISDN). Operators can save the trace results to handle any queries in the future.
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5.5 Performance Management Performance management assesses the SGSN9810 system and the surrounding networks and provides the data relating to network operation. The SGSN9810 performance management system has the following features:
Wide range of measurements
Diversified time attributes
Measurement templates
Measurement customization
Suspension and resuming of measurement tasks
Modification of measurement tasks
View of real-time data regarding performance measurement
Setting of measurement thresholds
5.6 Fault Management The alarm system monitors the operational status of the SGSN9810 and reports faults. The alarm system has the following features:
Comprehensive alarm information and accurate alarm identification The SGSN9810 provides over 300 types of alarm covering all software functions, hardware components, and system peripherals. The alarms are grouped into different categories with different severity levels. This ensures that all faults can be detected and handled in time.
Flexible and easy alarm handling The alarm terminal of the SGSN9810 provides flexible and convenient operations to ensure that you can handle the alarm effectively and in time.
5.7 Security Management The SGSN9810 ensures the security in two ways:
Privilege management The privilege of an operator is defined by a command set that contains a group of commands. Commands are assigned to a command set, and then a command set is assigned to an operator.
Operating log The operating log records all the user operations, including the user name, user ID, login IP address, command, time, and result.
5.8 CHR Call History Record (CHR) is an efficient and rapid fault location system. It can record the problems that occur in each user's call and store them in the server. When requiring records,
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the Network Management Department can query the call history records of a certain user and quickly locate the fault causes. Compared with the alarm and tracing systems, the CHR system focuses more on faults occurring in service use. The CHR system consists of the SGSN, CHR Server, and CHR Client, as shown in Figure 5-2.
Figure 5-2 CHR system architecture
CHR information CHR query request
CHR Client LAN
SGSN
LAN CHR query response CHR Server
CHR information
SGSN CHR Client
The functions of each part are described as follows:
SGSN Each USPU board collects CHR information. The information is sent to the UOMU board for convergence, storage, and transmission.
CHR Server The CHR Server receives the CHR information from the SGSN and stores it in the database. The Server also receives the CHR query instructions from the Client and returns the query results.
CHR Client
The CHR Client is used to browse and view the call records stored in the Server.
5.9 SSL The Secure Socket Layer (SSL) protocol is a secure connection technique provided by the network transmission layer, which is used between the browser and the Web server. The SSL provides the communication confidentiality, credibility, and identification authentication between two applications by using the Revest-Shamir-Adleman algorithm (RSA) and symmetric encipherment algorithm. It is regarded as the standard security measure applied to the Web browser and server on the Internet. The Internet Engineering Task Force (IETF) standardizes the SSL (RFC2246) and terms it Transport Layer Security (TLS).
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The SGSN encrypts the OM transmission channel by using the SSL protocol. The OM transmission channel consists of the mml channel between the M2000/LMT and the SGSN, binary channel between the M2000/LMT and the SGSN, and FTP transmission channel. By inserting the SSL into the transmission layer (TCP) and application layer (MML/binary commands), all the MML/binary commands and response messages can be encrypted in the transmission channel. Figure 5-3 shows the transmission model of the SSL channel. Figure 5-3 Transmission model of the SSL channel
Current OM transmission
Encrypted OM transmission
Application layer
MML command, BIN command
Transmission layer
TCP protocol
Application layer Transmission layer Transmission layer
MML command, BIN command SSL protocol TCP protocol
At present, the SGSN supports the SSL3.0, TSL1.0, and TSL1.1 versions. The FTP transmission channel is encrypted by the FTP Security (FTPS) protocol. The FTP server and FTP client support both of the encrypted and non-encrypted communication modes.
5.10 SSH Secure Shell (SSH) provides a secure channel between the LMT and the SGSN to ensure security of the SGSN maintenance interface. SSH provides the following functions for the SGSN:
Post-port (port forwarding function): encrypts the data transferred between the SGSN and the LMT; thus it guarantees data security.
SFTP: replaces the FTP Client carried by the LMT to realize secure file transfer.
STelnet: provides secure and reliable Telnet access, but it is unavailable currently.
MML character terminal: runs MML commands with the LMT not opened and provides secure protection for command packets.
As shown in Figure 5-4, SSH functions are realized by:
SSH Client: installed on the PC same with the LMT
SSH Server: Located at the UOMU board
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Figure 5-4 SSH composition UOMU
LMT terminal
LMT
BAM
LAN SSH Client
SSH Server
Insecure communication channel
Secure communication channel Internal communication channel
5.11 Online Help Both the SGSN9810 LMT and the iManager M2000 provide compressive and easy-to-use online help. The online help allows operators to quickly access required information during operation.
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Reliability
The SGSN9810 guarantees reliability from hardware, software, and charging.
6.1 Hardware Reliability The SGSN9810 uses the following reliability designs.
Board backup
Load sharing
Board fault detection and isolation
System fault detection and isolation
6.1.1 Board Hot Backup The SGSN9810 boards are configured in the 1+1 backup or N+1 redundancy. The following are the two major concerns in the backup design:
Board fault detection When a board is power-on, it checks its memory and the key external chips such as the network chips. Key signals (such as the clock signal) used by the board are monitored online. Loopback test of service code flow is conducted when the board is idle.
Switchover mechanism The active-standby switchover is carried out by two cross-connected signals between the active board and the standby board. They are the output signal effective to the active board and the input signal effective to the standby board.
6.1.2 ASIC Technology All the network chips used in the boards are special application specific integrated circuits (ASICs). These ASICs provide reliable measures to detect and report internal (chip-level) errors.
6.1.3 Quality Components The SGSN9810 uses quality components that have passed burn-in tests and proved to meet the requirements. The hardware is assembled under strict control to ensure that the system remains stable and reliable in the long term.
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6.1.4 Load Sharing Load sharing means that two or more boards perform relevant functions under normal operation. When one of the boards is faulty, other boards perform the task of the faulty board to ensure certain performance indexes (such as call loss). Load sharing is applied to secondary power modules, signaling links, and STM-1 interfaces.
6.1.5 Power Supply Reliability The SGSN9810 uses a distributed power supply. Each subrack or functional module has its own high-frequency DC/DC secondary power module that is highly efficient and stable. The secondary power supply adopts the active/standby hot backup design to ensure the reliable power supply. The power inputs and the external interfaces (such as the E1 interfaces) of boards provide protection against high voltages and current surges. The measures meet the international telecommunication union - telecommunication standardization sector (ITU-T) recommendation G.703 and other relevant specifications.
6.2 Software Reliability This section describes the measures that build up the reliability of the SGSN9810 software.
6.2.1 Reliability Building at Different Phases The key to improve software reliability is reducing software defects. The reliability of the SGSN9810 software is ensured at various phases from the system requirement analysis to the system test. From the requirements analysis phase, the software development is carried out under the guidance of various capability maturity model (CMM) specifications. This reduces errors in the initial phase. The SGSN9810 software is designed in modules. The modules are loosely coupled so that the fault of one module does not affect the performance of other modules. In additional, measures such as error check, error isolation, and recovery, are added to improve system reliability. Code walk-through, inspection, and tests at every phase further improve the software reliability.
6.2.2 Error Tolerance The error tolerance of a software system indicates the resilience of the system under minor software faults. That means the system does not break down on minor faults and has self-healing ability when an error occurs. The error tolerance of software involves the following measures:
Regular check of key resources For various software resources in the system (such as the network board resources), long-time seizure check mechanism is provided. If resources do no respond due to a software exception, the check mechanism releases the resources and generates logs and alarms.
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Task monitoring Output channels are provided for the internal software faults and some of the hardware faults detected during system operation. These output channels monitor the status of a task and report system exceptions to external devices.
Storage protection The software system uses the segment and page protection mechanism for the CPU memory management unit (MMU) to protect the storage of codes and important data segments. It also provides functions of online query, modification of variables and data, and memory monitoring.
Data check To ensure the consistency of the data on various service processing boards, the system performs regular or event-triggered consistency checks. It can also restore data consistency based on certain criteria and generate logs and alarms.
Operation log storage The SGSN9810 records user operations at a certain period and stores them in the system log. Faults can be located by analyzing the operation log for unknown errors in the system.
Load control In the case of CPU overload or resource congestion, the load control mechanism adjusts the load smoothly to avoid system down.
6.3 Charging Reliability Charging reliability ensures carriers' income. Charging reliability mainly means that charging information is correct, complete, and duplicate-free. The check mechanism offered by the protocol guarantees the correctness and no-repetition of charging information. The focus of the check mechanism is to ensure the accuracy of charging time. The SGSN9810 is provided with the NTP synchronization function to ensure the accuracy of charging time. The NTP synchronization function helps to obtain accurate timing information from the NTP server. The CG redirection and cache memory functions of the SGSN9810 ensure that the charging information is not discarded. The SGSN9810 can connect to multiple CGs. In case a certain CG has faults, the SGSN9810 can send charging information to other CGs. Even though all CGs have faults, the SGSN can save the charging information of seven days to the local hard disk. In this way, the charging information is not discarded.
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Technical Specifications
The technical specifications of the SGSN9810 mainly include performance specifications, clock indexes, physical interfaces, engineering parameters, and reliability parameters.
7.1 Performance Specifications Table 7-1 lists the performance specifications of the SGSN. Table 7-1 Performance specifications of the SGSN Name
Value (2.5G)
Value (3G)
Maximum number of attached subscribers
3 million
3 million
Maximum number of PDP context can be activated at the same time
3 million
3 million
Maximum packet data transfer capacity (pps)
300,000
4 million
Maximum packet data transfer flow
900 Mbit/s
10 Gbit/s
7.2 Physical Interfaces Table 7-2 shows the physical interfaces provided by the SGSN9810. Table 7-2 Physical interfaces provided by the SGSN9810 Interfaces
Physical Characteristics
Protocol
Maximum ports
Iu-PS (control plane)
STM-1 (single-mode and multi-mode)
ATM
80
STM-4 (single-mode and multi-mode)
ATM
40
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Interfaces
Physical Characteristics
Protocol
Maximum ports
Iu-PS (user plane)
STM-1 (single-mode and multi-mode)
ATM
80
STM-4 (single-mode and multi-mode)
ATM
40
Gigabit Ethernet(GE)
IP
80
Fast Ethernet(FE)
IP
80
GE
IP
80
FE
IP
80
STM-1
IP over ATM (IPOA)
80
STM-4
IPOA
40
Gb
E1/T1
FR
800
SS7
E1/T1
SS7
2 Mbit/s signaling links: 34; Or
Gn, Gp, Ga, X1-1, X2, and X3
64 Kbit/s signaling links: 1,088 O&M
FE
IP
2
The Gn, Gp, Ga, X1-1, X2, and X3 interfaces share 160 STM-1, 160 FE, 160 GE, and 80 STM-4 ports or a combination of these four types of physical port.
7.3 Clock Indexes Table 7-3 lists the primary technical parameters of the clock system in the SGSN9810. Table 7-3 Technical parameters of the clock system in the SGSN9810 Seque nce No.
Name
Index and Function
1
Clock network-entry parameters
Minimum accuracy
Stratum-2: ± 4 x 10-7
Pull-in range
Stratum-2: ± 4 x 10-7
Stratum-3: ± 4.6 x 10-6 Stratum-3: ± 4.6 x 10-6
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Name
Index and Function
Long-term phase variation
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Maximum frequency deviation
Stratum-2: 5 x 10-10 per day
Initial maximum frequency deviation
Stratum-2: less than 5 x 10-10 per day
Ideal working state
MRTIE ≤ 1 ms
Hold-in working state
MRTIE (ns) ≤ a x s + (1/2) x b x s2 + c
Stratum-3: 2 x 10-8 per day
Stratum-3: less than 1 x 10-8 per day
Where s refers to the time whose units is second, and the unit of MRTIE is ns. Stratum-2: a = 0.5
b = 1.16 x 10-5
c = 1,000
Stratum-3: a = 10 Working modes of the clock
3
Input jitter tolerance
4
Fast tracking
Tracing
Retaining
Free running
b = 2.3 x 10-4
c = 1,000
See Figure 7-1 for details.
Minimum accuracy: maximum deviation value of nominal frequency in a long period (20 years) without external frequency benchmark, that is, the clock is in free running state. Maximum frequency deviation: a maximum value of the clock's relative frequency change in a UI during a consecutive operation process. Pull-in range: maximum frequency bandwidth of the input signal locked by a clock MRTIE: The MRTIE extracts the offset that appears in measurements performed with local reference clocks.
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Figure 7-1 Maximum permissible lower limit of input jitter and wander Y (UI)
10
Peak-to-peak jitter and wander amplitude (logarithm)
2
A 0 =36.9 10 1
Slope: 20dB / 10 times of frequency interval
A1=1.5 1 A2=0.2 10 -1 1.2 × 10- 5 10
X 20
2.4 k
18 k
100 k
f (Hz)
When the jitter frequency of an input frequency is 1 kHz and the amplitude is more than 1.5 UI, you can infer that the input signal meets the requirements if the system operates normally. UI refers to the unit of time interval. One UI equals the reciprocal of the frequency of the digital signal. For example, the UI of the 2.048 Mbit/s signal is 488 ns.
7.4 Engineering Specifications Engineering specifications include the power consumption of the SGSN9810, dimensions and weight of cabinets, and environment requirements.
7.4.1 Power Consumption Table 7-4 lists the power consumption of the SGSN9810. Table 7-4 Power consumption of the SGSN9810 Parameter
Value
Power consumption of the 2G SGSN for 1 million users (Gb over TDM), with two cabinets and five subracks
2,250 W
Power consumption of the 2G SGSN for 2 million users (Gb over TDM), with two cabinets and eight subracks
3,850 W
Power consumption of the 2G SGSN for 3 million users (Gb over TDM), with three cabinets and eleven subracks
5,350 W
Power consumption of the 2G SGSN for 1 million users (Gb over IP), with two cabinets and five subracks
2,000 W
Power consumption of the 2G SGSN for 2 million users (Gb over IP), with two cabinets and eight subracks
3,420 W
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Power consumption of the 2G SGSN for 3 million users (Gb over IP), with three cabinets and elevent subracks
4,830 W
Power consumption of the 3G SGSN for 1 million users, with two cabinets and five subracks
1,880 W
Power consumption of the 3G SGSN for 2 million users, with two cabinets and seven subracks
3,030 W
Power consumption of the 3G SGSN for 3 million users, with three cabinets and ten subracks
4240W
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7.4.2 Dimensions and Weight of Cabinets Table 7-5 lists the dimensions and weight of a SGSN9810 cabinet. Table 7-5 Dimensions and weight of a SGSN9810 cabinet Parameter
Value
Cabinet dimension (H x W x D)
2200 mm x 600 mm x 800 mm
Cabinet weight
100 kg(with empty cabinet)
7.4.3 Environment Requirements Storage Environment The SGSN9810 complies with the "not temperature-controlled storage" requirements specified in European ETS 300 019-1-1. The SGSN9810 must be stored in the following environment:
Relative humidity: 10% to 100%
Temperature: –40°C to +70°C
Transportation Environment The SGSN9810 complies with "Class 2.3 Public transportation" requirements specified in the European ETS 300 019-1-2. The SGSN9810 must stay in the following environment:
Temperature: –40°C to +70°C
Relative humidity: 5% to 100%
Operational Environment The SGSN9810 complies with "Temperature-controlled locations" requirements specified in European ETS 300 019-1-3. The SGSN9810 must operate in the following environment:
Normal operation: temperature from 0°C to + 45°C, humidity from 5% to 85%
Safe operation: temperature from –5°C to + 55°C, humidity from 5% to 95%
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Safe operation indicates the conditions in which the SGSN9810 must not work for continuously over 96 hours and totally 15 days in a year.
Electromagnetic Compatibility The SGSN9810 complies with the GR-1089-CORE standard on electromagnetic compatibility.
Power Supply Power voltage range: –40 V to –57 V DC Input current: 50 A for a cabinet
7.5 Reliability Specifications Table 7-6 shows the reliability specifications of the SGSN9810. Table 7-6 Reliability specifications of the SGSN9810 Parameter
Value
System availability in typical configuration
≥ 99.999%
Mean time between failure (MTBF)
≥ 300,000 hours
Mean time to repair (MTTR)
≤ 30 minutes
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Installation
The installation of the SGSN9810 includes the installation of the hardware, the terminal software, and the board software. Hardware
The cabinets, subracks and cables are installed before delivery. Installation engineers only need to install external cables and boards. For board installation, the SGSN9810 provides coding slots so that installation engineers can insert boards only in the correct slots. This avoids damage to the board when an engineer attempts to install a board in a wrong slot. Terminal software
The SGSN9810 provides a standard Windows installation wizard to guide the installation of the terminal software. Following the instructions, field engineers can complete the installation easily. Board software
The SGSN9810 provides MML commands for installing software for all the boards or only specified boards. For detailed installation procedures, refer to the installation manuals delivered with the product.
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Acronyms and Abbreviations
Numeric 3GMS
3rd Generation Mobile Communications System
3GPP
3rd Generation Partnership Project
A AAA
Authentication, Authorization and Accounting
AAL2
ATM Adaptation Layer Type 2
ADMF
Administration Function
AF
Assured Forwarding
ALCAP
Access Link Control Application Part
APN
Access Point Name
ASIC
Application Specific Integrated Circuit
ATM
Asynchronous Transfer Mode
AUC
Authentication Center
B BC
Bear Channel
BE
Best-Effort
BG
Border Gateway
BITS
Building Integrated Timing Supply
BSC
Base Station Controller
BSS
Base Station Subsystem
BSSGP
Base Station Subsystem GPRS Protocol
BVC
BSSGP Virtual Connection
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C CAMEL
Customized Applications for Mobile network Enhanced Logic
CAR
Committed Access Rate
CBR
Constant Bit Rate
CBWFQ
Class-Based Weighted Fair Queuing
CC
Content of Communication
CDMA
Code Division Multiple Access
CDR
Charging Data Record
CG
Charging Gateway
CGF
Charging Gateway Functionality
CHR
Call History Record
CLNP
Connectionless Network Protocol
CM
Call Management
CMM
Capability Maturity Model
CN
Core Network
CN-CS
Core Network – Circuit Switch domain
CN-PS
Core Network – Packet Switch domain
CORBA
Common Object Request Broker Architecture
CPU
Center Processing Unit
D DC
Direct Current
DF
Delivery Function
DiffServ
Differential Services
DNS
Domain Name Server
DOPRA
Distributed Object-oriented Programmable Real time Architecture
DSCP
Differentiated Services Code Point
E EDGE
Enhanced Data rates for GSM Evolution
EF
Expedited Forwarding
EIR
Equipment Identification Register
EMS
Enhanced Messaging Service
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ETS
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European Telecommunication Standards
F FA
Foreign Agent
FE
Fast Ethernet
FR
Frame Relay
FTP
File Transfer Protocol
G GE
Gigabit Ethernet; Gigabit Ethernet
GERAN
GSM/EDGE Radio Access Network
GGSN
Gateway GPRS Support Node
GMLC
Gateway Mobile Location Center
GPRS
General Packet Radio Service
gsmSCF
GSM Service Control Function
gprsSSF
GPRS Service Switching Function
GSM
Global System for Mobile Communications
GSN
GPRS Support Node
GTP
GPRS Tunneling Protocol
GTP-C
Control plane part of GPRS tunneling protocol
GTP-U
User plane part of GPRS tunneling protocol
GUI
Graphic User Interface
H HA
Home Agent
HLR
Home Location Register
HPLMN
Home PLMN
HSDPA
High Speed Downlink Packet Access
HSS
Home Subscriber Server
I I-CSCF
Interrogating- Call State Control Function
IETF
Internet Engineering Task Force
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IGP
Interior Gateway Protocol
IMEISV
International Mobile station Equipment Identity and Software Version number
IMS
IP Multimedia Subsystem
IMSI
International Mobile Subscriber Identity
IP
Internet Protocol
IPSec
Internet Protocol Security extensions
IRI
Intercept Related Information
ISDN
Integrated Services Digital Network
IS-IS
Intermediate System-Intermediate System
ISO
International Organization for Standardization
ITU-T
International Telecommunication Union - Telecommunication Standardization Sector
IuUP
Iu User Plane
L LA
Location Area
LAN
Local Area Network
LCS
LoCation Service
LEA
Law enforcement agency
LIS
Logical IP Subnet
LLC
Logical Link Control
LMT
Local Maintenance Terminal
M MAC
Media Access Control
MAP
Mobile Application Part
MBR
Mobility Binding Record
MGW
Media Gateway
MIP
Mobile IP
MM
Mobility Management
MML
Man-Machine Language
MMU
Multiplication and Management Unit
MNO
Mobile Network Operator
MO
Mobile Originated
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MS
Mobile Station
MSC
Mobile Service Switching Center
MSISDN
Mobile Station International ISDN Number
MT
Mobile Terminated
MTBF
Mean Time Between Failures
MTP3
Message Transfer Part 3rd Layer
MTP3B
Message transfer part (broadband)
MVNO
Mobile Virtual Network Operator
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N NACC
Network Assisted Cell Change
NS
Network Service
NS-VC
Network Service Virtual Connection
NTP
Network Time Protocol
O OS
Operational System
OSI
Open System(s) Interconnection
OSPF
Open Shortest Path First
P P-CSCF
Proxy CSCF
PDN
Public Data Network
PDP
Packet Data Protocol
PDU
Packet Data Unit
PHB
Per-Hop Behaviors
PLMN
Public Land Mobile Network
POS
Packet Over SDH
PPP
Point-to-Point Protocol
PS
Packet Switched
PSM
Packet Service Module
PSTN
Public Switched Telephone Network
PTP
Point To Point
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Q QoS
Quality of Service
R RA
Routing Area
RADIUS
Remote Authentication Dial in User Service
RAN
Radio Access Network
RANAP
Radio Access Network Application Part
RRC
Radio Resource Control
RIP
Routing Information Protocol
RIPng
RIP next generation
RNC
Radio Network Controller
S SAAL
Signaling ATM Adaptation Layer
SC
Service Center
SCCP
Signaling Connection and Control Part
SCP
Service Control Point
S-CSCF
Serving CSCF
SCTP
Stream Control Transport Protocol
SDH
Synchronous Digital Hierarchy
SGSN
Serving GPRS Support Node
SIP
Session Initiation Protocol
SM
Session Management
SME
Short Message Entity
SMS
Short Message Service
SM-SC
Short Message Service - Service Centre
SMS-GMSC
Short Message Service Gateway MSC
SMS-IWMSC
Short Message Service Interworking MSC
SNA
Shared Network Area
SNDCP
SubNetwork Dependent Convergence Protocol
SNMP
Simple Network Management Protocol
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SOHO
Small Office and Home Office
SPF
Shortest Path First
SPUA
SCTP Private User Adaptation Layer
SRNC
Serving RNC
SS7
CCITT Signaling System No.7
SSH
Secure Shell
SSP
Service Switching Point
STM-1
SDH Transport Module -1
STM-4
SDH Transport Module -4
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T TCP
Transport Control Protocol
TE
Terminal Equipment
TEID
Tunnel End ID
U UACU
Auxiliary Control Unit
UALU
PSM Alarm Unit
UBIU
PSM Back Interface Unit
UBR
Unspecified Bit Rate
UBSU
Back Storage Unit
UCDR
Charging Detail Record unit
UCKI
Clock Unit
UDP
User Datagram Protocol
UE
User Equipment
UEPI
E1 Processing Interface unit
UESBI
UE Specific Behavior Information
UFCU
Frame Connect Unit
UFSU
Flash Storage Unit
UGBI
GB Interface unit
UGFU
GTP Forwarding Unit
UGTP
GTP processing unit
UICP
Iu_PS Control Processing unit
Issue V1.0 (2009-03-30)
Commercial in Confidence
Page 80 of 81
GSM-R SGSN9810 Product Description
ULAN
LAN-SWITCH card
ULIP
Lawful Interception Processing unit
ULEP
Lawful Interception Enhanced Processing Unit
UMTS
Universal mobile telecommunication services
UOMU
Packet Service O&M Unit
UPIU
Packet Interface Unit
UPWR
PSM Power module
URCU
sub-Rack Control Unit
USIG
SIGTRAN Processing Unit
USPU
Packet Service Signal Processing Unit
USS7
SS7 Signaling Link Processing Unit
UTPI
T1 Processing Interface unit
UTRAN
UMTS Terrestrial radio access network
Confidential
V VBR
Variable Bit Rate
VLAN
Visual LAN
VLR
Visitor Location Register
VMSC
Visited Mobile Switching Center , Visited MSC
VPLMN
Visited PLMN
VPN
Virtual Private Network
W WCDMA
Wideband Code Division Multiple Access
WRED
Weighted Random Early Detection
Issue V1.0 (2009-03-30)
Commercial in Confidence
Page 81 of 81
