Emulation of the IP Core Network for Testing of the Service GPRS Support Node (SGSN) Routing Application
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Technical report, IDE0959, November 2009 Emulation of the IP Core Network for Testing of the Service GPRS Support Node (SGSN) Routing Application Master’s Thesis in Computer Network Engineering Hossein Torkaman School of Information Science, Computer and Electrical Engineering Halmstad University Emulation of the IP Core Network for Testing of the Service GPRS Support Node (SGSN) Routing Application Master’s thesis in Computer Network Engineering School of Information Science, Computer and Electrical Engineering Halmstad University Box 823, S-301 18 Halmstad, Sweden November 2009 Description of cover page picture: IP Core Network picture on GPRS Networks. Preface The following report is based on the data and information gathered through literature studies, Ericsson’s Intranet documents and other several GPRS standards published by 3rd Generation Partnership Project (3GPP), observations, emulating different IP core network scenarios, meetings and executed experiments during December 2008 - August 2009 at Ericsson AB Lindholmen. The input martial to this thesis formed primarily by Internet Protocols and Drivers section in Product Development Department Packet Core at Ericsson AB, Göteborg, Sweden with leadership of Gunilla Zachrisson, my supervisor, to whom I should give an immense thank you due to her kind guidance on each phase of project and for her valuable supports on the implementation of improvements. I am also thankful to my manager, Matthew Crockett, who also made me feel welcomed at Ericsson AB Lindholmen. A big thanks is also directed to my supervisor at Halmstad University, Tony Larsson, for pointing me in the right direction and for the feedback regarding the performance of the project. I would also like to use this opportunity to thank Colin Taylor and Daniel Nilsson and all other colleagues at Ericsson, for interrupting their busy schedules in order to provide me with their technical feedback and experience. Hossein Torkaman Halmstad University, November 2009 i ii Abstract This thesis aims to investigate a method and tool for emulation of the General Packet Radio Service (GPRS) core network needed as an environment to test the routing functionality. GPRS is the most widely adopted mobile packet data delivery technology in the world. It utilizes an Intranet Protocol (IP)-based core network and involves significant changes to the way the Global System for Mobile communications (GSM) air interface is structured. It also forms the basis of the future structure of mobile network transmission and switching. The Serving GPRS Support Node (SGSN) is the most fundamental node in GPRS. Ericsson produces and manages an increasing number of SGSN nodes in the world. One of main functionalities of SGSN node is to forward IP packets according to the destination address in the IP header on IP core network. In each new release of SGSN, or when implementation or upgrades have been done on routing application on SGSN, design and test engineers at Ericsson need to emulate the IP core network. This must be done with use of many routers to generate huge amounts of data that can simulate the real world IP core network. The major goal of this thesis was to analyze and verifying the use of a suitable and economical solution to emulating IP Core Network of the GPRS system for testing of different functionality of the routing application running in SGSN , instead of building up a physical Core Network with different infrastructure and many routers. The method chosen for emulating the IP core network with many routers, and investigated in the thesis, is based on a Cisco simulator called “Dynamips”, which runs many actual Cisco Internetwork Operating Systems (IOS) with many different models of Cisco products in a virtual environment on Windows or Linux platforms. With this simulator, engineers at Ericsson will be able to use this simulator to emulate IP core network easily and efficiently to accomplish system test cases. A conclusion of this work is that Dynamips could be used to emulate many complicated IP core network scenarios, with many routers to generate huge amounts of data to simulate the real world IP core network. The emulated system fulfils its purpose for testing of the routing application of SGSN regarding different functionality and characteristics. This is done to ensure and verify that SGSN routing application meets its functional and technical requirements, and also helps to find undiscovered errors as well as helps to ensure that the individual components of routing application on SGSN are working correctly. iii Abbreviations 3GPP 3rd Generation Partnership Project Appl-C Application-control plane Appl-U Application-user plane AS Autonomous System ASE Autonomous System External ATM Asynchronous Transfer Mode BFD Bi-directional Forwarding Detection BGP Border Gateway Protocol BS Billing System BSC Base Station Controller CGF Charging Gateway Function CS Circuit Switching DNS Domain Name System EBGP External Border Gateway Protocol FE Forwarding Engine GGSN Gateway GPRS Support Node: GPRS General Packet Radio Service GRE Generic Routing Encapsulation GSM Global System for Mobile communications GSN GPRS Support Nodes IBGP Internal Border Gateway Protocol ICMP Internet Control Message Protocol IOS Cisco Internetwork Operating Systems IP Internet Protocol IP Intranet Protocol IPSec IP Security Protocol LSA Link state Advertisement MMS Multimedia Messaging Service MS Mobile stations NCB Node Controller Board NGRS Next Generation Routing Application O&M Operation and Maintenance OCS Online Charging System OSPF Open Shortest Path First PCRF Policy and Charging Rules Function PDN Packet Data Network PDP Packet Data Protocol PIU Plug-In Unit PLMN Public Land Mobile Network PM Performance Monitoring PS Packet Switching PSTN Switched Telephone Network PVC Permanent Virtual Circuit QoS Quality of Service iv RBS Radio Base Station RIP Routing Information Protocol SACC Service Aware Charging and Control SAU Simultaneously Attached Users SGSN Serving GPRS Support Node SMS Short Message Service SS7 Signalling System 7 UDP User Datagram Protocol VLAN Virtual Local Area Network VPN Virtual Private Networks WAP Wireless Application Protocol WCDMA Wideband Code Division Multiple Access v Contents 1 INTRODUCTION ........................................................................................................................................... 1 1.1 BACKGROUND.............................................................................................................................................. 1 1.2 PROBLEM AREA ........................................................................................................................................... 1 1.3 GOALS ......................................................................................................................................................... 2 1.4 METHOD FOR EMULATING IP CORE NETWORK ............................................................................................ 2 2 GPRS SYSTEM OVERVIEW AND ROUTING FUNCTIONALITY IN SGSN........................................................ 4 2.1 INTRODUCTION ............................................................................................................................................ 4 2.2 CIRCUIT SWITCHING AND PACKET SWITCHING ............................................................................................. 4 2.3 GPRS SYSTEM OVERVIEW .......................................................................................................................... 4 2.4 SERVICES WITH GPRS ................................................................................................................................. 5 2.5 PACKET DATA ............................................................................................................................................. 5 2.6 GPRS END-USER SERVICES ........................................................................................................................ 5 2.7 GPRS SYSTEM ARCHITECTURE OVERVIEW ................................................................................................. 6 2.8 GPRS CORE NETWORK NODES.................................................................................................................... 7 2.8.1 Serving GPRS Support Node (SGSN).................................................................................................... 7 2.8.2 Gateway GPRS Support Node (GGSN) ................................................................................................. 8 2.9 IP ROUTING ................................................................................................................................................. 8 2.10 GPRS BACKBONE NETWORKS..................................................................................................................... 9 2.11 PACKET ROUTING AND TRANSFER FUNCTIONS.......................................................................................... 10 2.12 ROUTING METHODOLOGY IN SGSN .......................................................................................................... 10 2.13 ROUTING PROTOCOLS ................................................................................................................................11 2.13.1 Open Shortest Path First version 2 (OSPFv2) ................................................................................. 11 2.13.2 Border Gateway Protocol version 4 (BGPv4) ................................................................................