《计算机网络》课程PPT教学课件（自顶向下方法，英文第三版）第七章 Multimedia Networking

Chapter 7 Multimedia Networking computer networking A note on the use of these ppt slides: We're making these slides freely available to all (faculty,students,readers). They're in PowerPoint form so you can add,modify.and delete slides (including this one)and slide content to suit your needs.They obviously represent a lot of work on our part.In return for use,we only ask the Computer Networking:A Top following: Down Approach Featuring the If you use these slides(e.g.in a class)in substantially unaltered form. Internet, that you mention their source (after all,we'd like people to use our book!) 3rd edition. If you post any slides in substantially unaltered form on a ww site,that Jim Kurose.Keith Ross you note that they are adapted from (or perhaps identical to)our slides.and Addison-Wesley,July 2004 note our copyright of this material. Thanks and enjoy!JFK/KWR All material copvriaht 1996-2006 J.F Kurose and K.W.Ross,All Rights Reserved 7:Multimedia Networking 7-1

7: Multimedia Networking 7-1 Chapter 7 Multimedia Networking A note on the use of these ppt slides: We’re making these slides freely available to all (faculty, students, readers). They’re in PowerPoint form so you can add, modify, and delete slides (including this one) and slide content to suit your needs. They obviously represent a lot of work on our part. In return for use, we only ask the following: ❑ If you use these slides (e.g., in a class) in substantially unaltered form, that you mention their source (after all, we’d like people to use our book!) ❑ If you post any slides in substantially unaltered form on a www site, that you note that they are adapted from (or perhaps identical to) our slides, and note our copyright of this material. Thanks and enjoy! JFK / KWR All material copyright 1996-2006 J.F Kurose and K.W. Ross, All Rights Reserved Computer Networking: A Top Down Approach Featuring the Internet, 3 rd edition. Jim Kurose, Keith Ross Addison-Wesley, July 2004

Multimedia,Quality of Service:What is it? Multimedia applications: network audio and video ("continuous media") QoS network provides application with level of performance needed for application to function. 7:Multimedia Networking 7-2

7: Multimedia Networking 7-2 Multimedia, Quality of Service: What is it? Multimedia applications: network audio and video (“continuous media”) network provides application with level of performance needed for application to function. QoS

Chapter 7:Goals Principles Classify multimedia applications Identify the network services the apps need Making the best of best effort service Mechanisms for providing QoS Protocols and Architectures Specific protocols for best-effort Architectures for QoS 7:Multimedia Networking 7-3

7: Multimedia Networking 7-3 Chapter 7: Goals Principles  Classify multimedia applications  Identify the network services the apps need  Making the best of best effort service  Mechanisms for providing QoS Protocols and Architectures  Specific protocols for best-effort  Architectures for QoS

Chapter 7 outline ▣7.1 Multimedia 7.6 Beyond Best Networking Applications Effort ▣7.2 Streaming stored 7.7 Scheduling and audio and video Policing Mechanisms 7.3 Real-time Multimedia: 7.8 Integrated Internet Phone study Services and 7.4 Protocols for Real- Differentiated Time Interactive Services Applications ▣7.9RSVP RTPRTCP SIP 7.5 Distributing Multimedia:content distribution networks 7:Multimedia Networking 7-4

7: Multimedia Networking 7-4 Chapter 7 outline  7.1 Multimedia Networking Applications  7.2 Streaming stored audio and video  7.3 Real-time Multimedia: Internet Phone study  7.4 Protocols for Real￾Time Interactive Applications  RTP,RTCP,SIP  7.5 Distributing Multimedia: content distribution networks  7.6 Beyond Best Effort  7.7 Scheduling and Policing Mechanisms  7.8 Integrated Services and Differentiated Services  7.9 RSVP

MM Networking Applications Classes of MM applications: Fundamental 1)Streaming stored audio characteristics: and video Typically delay sensitive 2)Streaming live audio and o end-to-end delay video o delay jitter 3)Real-time interactive 口But loss tolerant: audio and video infrequent losses cause minor glitches ▣Antithesis of data, which are loss intolerant Jitter is the variability but delay tolerant. of packet delays within the same packet stream 7:Multimedia Networking 7-5

7: Multimedia Networking 7-5 MM Networking Applications Fundamental characteristics:  Typically delay sensitive  end-to-end delay  delay jitter  But loss tolerant: infrequent losses cause minor glitches  Antithesis of data, which are loss intolerant but delay tolerant. Classes of MM applications: 1) Streaming stored audio and video 2) Streaming live audio and video 3) Real-time interactive audio and video Jitter is the variability of packet delays within the same packet stream

Streaming Stored Multimedia Streaming: media stored at source transmitted to client streaming:client playout begins before all data has arrived timing constraint for still-to-be transmitted data:in time for playout 7:Multimedia Networking 7-6

7: Multimedia Networking 7-6 Streaming Stored Multimedia Streaming:  media stored at source  transmitted to client  streaming: client playout begins before all data has arrived  timing constraint for still-to-be transmitted data: in time for playout

Streaming Stored Multimedia: What is it? aAlDnwn 2.video sent 1.video 3.video received recorded network played out at client delay time streaming:at this time,client playing out early part of video, while server still sending later part of video 7:Multimedia Networking 7-7

7: Multimedia Networking 7-7 Streaming Stored Multimedia: What is it? 1. video recorded 2. video sent 3. video received, played out at client streaming: at this time, client playing out early part of video, while server still sending later part of video network delay time

Streaming Stored Multimedia:Interactivity VCR-like functionality:client can pause,rewind,FF,push slider bar 10 sec initial delay OK o1-2 sec until command effect OK o RTSP often used (more later) timing constraint for still-to-be transmitted data:in time for playout 7:Multimedia Networking 7-8

7: Multimedia Networking 7-8 Streaming Stored Multimedia: Interactivity  VCR-like functionality: client can pause, rewind, FF, push slider bar  10 sec initial delay OK  1-2 sec until command effect OK  RTSP often used (more later)  timing constraint for still-to-be transmitted data: in time for playout

Streaming Live Multimedia Examples: Internet radio talk show ▣Live sporting event Streaming playback buffer playback can lag tens of seconds after transmission still have timing constraint Interactivity fast forward impossible rewind,pause possible! 7:Multimedia Networking 7-9

7: Multimedia Networking 7-9 Streaming Live Multimedia Examples:  Internet radio talk show  Live sporting event Streaming  playback buffer  playback can lag tens of seconds after transmission  still have timing constraint Interactivity  fast forward impossible  rewind, pause possible!

Interactive,Real-Time Multimedia applications:IP telephony, video conference,distributed interactive worlds end-end delay requirements: o audio:150 msec good,400 msec OK includes application-level (packetization)and network delays higher delays noticeable,impair interactivity session initialization o how does callee advertise its IP address,port number,encoding algorithms? 7:Multimedia Networking 7-10

7: Multimedia Networking 7-10 Interactive, Real-Time Multimedia  end-end delay requirements:  audio: < 150 msec good, < 400 msec OK • includes application-level (packetization) and network delays • higher delays noticeable, impair interactivity  session initialization  how does callee advertise its IP address, port number, encoding algorithms?  applications: IP telephony, video conference, distributed interactive worlds