Ericsson, Netherlands Faculty of Electrical Engineering, Mathematics and Computer Science Network Architectures and Services Video over Internet: Analysis using SIP, RTP/RTCP Protocols A.O. Ajagbe (1535617) Committee members: Mentor : Rogier Noldus, Msc. Chairman : dr. ir. F.A. Kuipers Member : Dr. E. Onur October, 2010 M.Sc. Thesis No: PVM 2010 – 067 Copyright ©2010 by A.O. Ajagbe All rights reserved. No part of the material protected by this copyright may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording or by any information storage and retrieval system, without the permission from the author and Delft University of Technology. Video over Internet Protocol (VIP): Acknowledgements Analysis using SIP, RTP/RTCP Protocols Acknowledgements While working on my thesis, I have received immense help and support from staff at Ericsson, TU Delft as well as from my family and friends. From Ericsson, I would like to thank my thesis supervisor, Rogier Noldus for his guidance and advice and for always having time to answer all my numerous questions. I would also like to thank my parents, Mr. & Mrs. S.O. Ajagbe, for their encouragement and financial support throughout the course of my programme at TUDelft. My sincere gratitude also goes to my siblings, Opeyemi and Damilola and extended family for their encouragement and support. My appreciation also goes to Chief Hezekiah Adediji for his support. Lastly but definitely not the least, I thank my wife, Oluwatomilayo, for her love, support and patience that gave me the energy to complete the work presented in this report. iii Video over Internet Protocol (VIP): Acknowledgements Analysis using SIP, RTP/RTCP Protocols To my beloved ones, with whom I share my challenges and rewards iv Video over Internet Protocol (VIP): Abstract Analysis using SIP, RTP/RTCP Protocols Abstract The goal of this project is to analyze video calls over the Internet Protocol (Video over IP) using a simulated IMS environment (IMS-in-a-box). The thesis presents an overview of IMS, its purpose and how it has evolved. The thesis also attempts to give the reader a full and comprehensible understanding of what the IMS is all about, its purpose and why it came into existence. The thesis considers a number of different video call case scenarios that are most likely to be encountered when making video calls over the Internet using the Internet protocol. This analysis focuses mainly on the SIP, RTP/RTCP protocols and how these three protocols are related and synchronized in order to actually know what is happening during the course of call set up and media exchange between the various end callers involved. The report looks into aspects of bandwidth consumption by the exchanged media (RTP and RTCP), jitter and its variation over the duration of the calls and the cooperation between the control plane and the user plane in order for a smooth call set up, media exchange and release of network resources. The thesis focuses on the areas of interest mentioned above, as these protocols have been identified as being of high significance in media transfer during video calls over IP. Keywords: Voice over IP, IP Multimedia Subsystem, Video over IP, SIP, RTP/RTCP. v Video over Internet Protocol (VIP): Abstract Analysis using SIP, RTP/RTCP Protocols vi Video over Internet Protocol (VIP): Contents Analysis using SIP, RTP/RTCP Protocols Contents 1. Introduction ................................................................................................................ 1 1.1 Background ......................................................................................................... 1 1.2 Objective of the thesis and scope of work ......................................................... 1 1.3 Methodology and thesis structure ..................................................................... 2 2. Introduction to Voice over Internet Protocol (VoIP) .................................................. 3 2.1 Definition of the domains for communication over the Internet ...................... 3 2.2 Basics of VoIP ...................................................................................................... 3 2.3 Media streams for VoIP ...................................................................................... 4 2.4 Defining Internet domains for VoIP .................................................................... 4 2.4.1. Roles of various domains ............................................................................ 5 2.5 First step in communicating over the Internet (peer-to-peer media exchange). …………………………………………………………………………………………………………………….. ..6 2.5.1 Media exchange with flow control ............................................................. 6 2.6 User-to-user SIP signaling ................................................................................... 6 2.6.1 SIP signaling (voice call establishment) ...................................................... 7 2.7 Changing of roles between UAC and UAS........................................................... 8 2.8 The Registrar ....................................................................................................... 9 2.8.1 Registration ............................................................................................... 10 2.8.2 The inbound proxy .................................................................................... 10 2.8.3 Signaling for inbound proxy (registration) ................................................ 10 2.8.4 Signaling for inbound proxy (call establishment) ..................................... 11 2.9 The Location Register ........................................................................................ 11 2.9.1 Signaling for inbound proxy and Location server (call establishment) .... 12 2.10 User-to-network proxy (protected access to the network).............................. 12 2.11 Layered signaling: control plane and user plane .............................................. 14 2.11.1 Synchronization of the control plane and the user plane ........................ 15 3. IP Multimedia Subsystem (IMS) ................................................................................ 17 3.1 Introduction to IMS ........................................................................................... 17 3.2 History of IMS ................................................................................................... 17 3.3 Benefits of IMS .................................................................................................. 18 3.4 IMS Protocols .................................................................................................... 19 3.4.1. Session Initiation Protocol (SIP) ................................................................ 19 3.4.2. Session Description Protocol .................................................................... 20 3.4.3. Real-time Transport Protocol ................................................................... 21 3.4.4. The AAA Protocol ...................................................................................... 21 3.4.5. H.248 MEGACO ......................................................................................... 21 3.5 IMS architecture ............................................................................................... 22 3.6 Core IMS functional elements and related elements ....................................... 25 3.6.1. Call Session Control Function.................................................................... 25 3.6.2. Application Servers ................................................................................... 29 3.6.3. Service Capability and Interaction Manager ............................................. 30 3.6.4. The Databases: the HSS and the SLF ......................................................... 30 vii Video over Internet Protocol (VIP): Contents Analysis using SIP, RTP/RTCP Protocols 3.6.5. The Media Resource Function .................................................................. 31 3.6.6. MGW/MGCF/SGW/BGCF .......................................................................... 31 3.7 Identification in the IMS ................................................................................... 32 3.7.1. Public User Identity ................................................................................... 32 3.7.2. Private User Identity ................................................................................. 33 3.8 SIM, USIM and ISIM in 3GPP ............................................................................. 34 4. Video Telephony ....................................................................................................... 35 4.1 Introduction to Video telephony ...................................................................... 35 4.2 Concept of transmitting video stream over the Internet ................................. 37 4.2.1. Video requirements .................................................................................. 38 4.2.2. Video compression standards ................................................................... 39 4.3 Transport protocols .......................................................................................... 41 4.4 Establishing video session over IP..................................................................... 42 4.5 Encoding data streams into RTP messages ......................................................