1、 IEEE Standard for Layer 3 Transport Protocol for Time-Sensitive Applications in Local Area Networks Sponsored by the Microprocessor Standards Committee IEEE 3 Park Avenue New York, NY 10016-5997 USA 25 April 2011 IEEE Computer Society IEEE Std 17332011 IEEE Std 1733-2011 IEEE Standard for Layer 3 T
2、ransport Protocol for Time-Sensitive Applications in Local Area Networks Sponsor Microprocessor Standards Committee of the IEEE Computer Society Approved 31 March 2011 IEEE-SA Standards Board Approved 27 March 2012 American National Standards Institute Abstract: Protocol, data encapsulations, connec
3、tion management, and presentation time procedures used to ensure interoperability between audio and video-based end stations that use standard networking services provided by all IEEE 802 networks meeting QoS requirements for time-sensitive applications by leveraging the Real-time Transport Protocol
4、 (RTP) family of protocols and IEEE 802.1 Audio/Video Bridging (AVB) protocols is specified in this standard. Keywords: bridged LAN, IEEE 802.1AS, IEEE 802.1 AVB protocols, IEEE 802.1Qat, IEEE 802.1Qav, IEEE 1733, LAN, QoS, RTCP, RTP, time-sensitive media streaming, time synchronization The Institut
5、e of Electrical and Electronics Engineers, Inc. 3 Park Avenue, New York, NY 10016-5997, USA Copyright 2011 by the Institute of Electrical and Electronics Engineers, Inc. All rights reserved. Published 25 April 2011. Printed in the United States of America. IEEE and 802 are registered trademarks in t
6、he U.S. Patent +1 978 750 8400. Permission to photocopy portions of any individual standard for educational classroom use can also be obtained through the Copyright Clearance Center. Copyright 2011 IEEE. All rights reserved. ivIntroduction This introduction is not part of IEEE Std 1733-2011, IEEE St
7、andard for Layer 3 Transport Protocol for Time-Sensitive Applications in Local Area Networks. This standard specifies the protocol, data encapsulations, connection management and presentation time procedures used to ensure interoperability between audio and video based end stations that use standard
8、 networking services provided by all IEEE 802 networks meeting quality of service (QoS) requirements for time-sensitive applications by leveraging the Real-time Transport Protocol (RTP) family of protocols and family of IEEE 802.1 Audio/Video Bridging (AVB) protocols. Notice to users Laws and regula
9、tions Users of these documents should consult all applicable laws and regulations. Compliance with the provisions of this standard does not imply compliance to any applicable regulatory requirements. Implementers of the standard are responsible for observing or referring to the applicable regulatory
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14、rigenda, or errata, visit the IEEE Standards Association web site at http:/ieeexplore.ieee.org/xpl/standards.jsp, or contact the IEEE at the address listed previously. For more information about the IEEE Standards Association or the IEEE standards development process, visit the IEEE-SA web site at h
15、ttp:/standards.ieee.org. Errata Errata, if any, for this and all other standards can be accessed at the following URL: http:/standards.ieee.org/reading/ieee/updates/errata/index.html. Users are encouraged to check this URL for errata periodically. Copyright 2011 IEEE. All rights reserved. vInterpret
16、ations Current interpretations can be accessed at the following URL: http:/standards.ieee.org/reading/ieee/interp/ index.html. Patents Attention is called to the possibility that implementation of this standard may require use of subject matter covered by patent rights. By publication of this standa
17、rd, no position is taken with respect to the existence or validity of any patent rights in connection therewith. The IEEE is not responsible for identifying Essential Patent Claims for which a license may be required, for conducting inquiries into the legal validity or scope of Patents Claims or det
18、ermining whether any licensing terms or conditions provided in connection with submission of a Letter of Assurance, if any, or in any licensing agreements are reasonable or non-discriminatory. Users of this standard are expressly advised that determination of the validity of any patent rights, and t
19、he risk of infringement of such rights, is entirely their own responsibility. Further information may be obtained from the IEEE Standards Association. Copyright 2011 IEEE. All rights reserved. viParticipants At the time this IEEE standard was completed, the Layer 3 Transport Protocol for Time-Sensit
20、ive Applications Working Group had the following membership: Suman Sharma, Chair Roshni Chatterjee, Editor Alan Bartky Robert Boatright Debin Chen George Claseman John Fuller Kevin Gross Craig Gunther Christopher Hall Faisal Haq Chuck Harrison Raghu Kondapalli Lee Minich Matt Xavier Mora David Olsen
21、 Don Pannell Kevin Stanton Michael Johas Teener Greg Thompson Fred Tuck Kevin Vanwulpen Ganesh Venkatesan Niel Warren The following members of the individual balloting committee voted on this standard. Balloters may have voted for approval, disapproval, or abstention. Hugh Barrass Leslie Baxter Mart
22、in J. Bishop Robert Boatright Tomo Bogataj Juan Carreon Peng Chen Keith Chow Thomas Dineen Geoffrey Garner Randall Groves John Harauz Werner Hoelzl Anthony Jeffree Piotr Karocki Yongbum Kim Daniel Levesque Greg Luri Arthur Marris Michael S. Newman David Olsen Chris Osterloh Robert Robinson Michael R
23、ush John Sargent Bartien Sayogo Suman Sharma Gil Shultz Kevin Stanton Walter Struppler Michael Johas Teener David Thompson Oren YuenCopyright 2011 IEEE. All rights reserved. viiWhen the IEEE-SA Standards Board approved this standard on 31 March 2011, it had the following membership:Richard H. Hulett
24、, Chair John Kulick, Vice Chair Robert M. Grow, Past Chair Judith Gorman, Secretary Masayuki Ariyoshi William Bartley Ted Burse Clint Chaplin Wael Diab Jean-Philippe Faure Alexander Gelman Paul Houz Jim Hughes Joseph L. Koepfinger* David J. Law Thomas Lee Hung Ling Oleg Logvinov Ted Olsen Gary Robin
25、son Jon Walter Rosdahl Sam Sciacca Mike Seavey Curtis Siller Phil Winston Howard L. Wolfman Don Wright *Member Emeritus Also included are the following nonvoting IEEE-SA Standards Board liaisons: Satish Aggarwal, NRC Representative Richard DeBlasio, DOE Representative Michael Janezic, NIST Represent
26、ative Michelle Turner IEEE Standards Program Manager, Document Development Malia Zaman IEEE Standards Program Manager, Technical Program Development Copyright 2011 IEEE. All rights reserved. viiiContents 1. Overview 1 1.1 Scope . 2 1.2 Purpose 2 2. Normative references 2 3. Definitions 2 4. Abbrevia
27、tions and acronyms 3 5. Real-time Transport Protocol (RTP) and IEEE 802.1 AVB. 4 5.1 RTP 4 5.2 IEEE 802.1 Audio video bridging (AVB) . 5 6. Operation of RTP over AVB 5 6.1 IEEE Std 802.1AS-2011 5 6.2 IEEE Std 802.1Qat-2009 . 6 7. RTP and network stack. 7 8. AVB RTCP usage. 7 8.1 V, P, SSRC/CSRC. 8 8
28、.2 PT (8 bits) 8 8.3 Subtype (5 bits) 8 8.4 Length (16 bits) . 8 8.5 Name (32 bits) . 9 8.6 gm TimeBaseIndicator (16 bits) 9 8.7 gmIdentity (80 bits) . 9 8.8 stream_id (IEEE 802.1Q stream identifier) (64 bits). 9 8.9 as_timestamp (32 bits). 9 8.10 rtp_timestamp field (32 bits) . 9 9. Translator rule
29、s for AVB RTCP packet 10 10. Different payload format support . 10 Annex A (informative) Bibliography . 11 Copyright 2011 IEEE. All rights reserved. 1IEEE Standard for Layer 3 Transport Protocol for Time-Sensitive Applications in Local Area Networks IMPORTANT NOTICE: This standard is not intended to
30、 ensure safety, security, health, or environmental protection. Implementers of the standard are responsible for determining appropriate safety, security, environmental, and health practices or regulatory requirements. This IEEE document is made available for use subject to important notices and lega
31、l disclaimers. These notices and disclaimers appear in all publications containing this document and may be found under the heading “Important Notice” or “Important Notices and Disclaimers Concerning IEEE Documents.” They can also be obtained on request from IEEE or viewed at http:/standards.ieee.or
32、g/IPR/disclaimers.html. 1. Overview The Real-time Transport Protocol (RTP) family of protocols is one of the most commonly used protocols for streaming real-time media across packet networks. While RTP is widely used for media streaming, as originally defined it did not take advantage of recent laye
33、r-2 standards created by the IEEE 802.1 Audio Video Bridging (AVB) task group for time-sensitive media streaming. These standards, collectively referred to as the AVB standards, include accurate timing (IEEE Std 802.1AS-2011),1a reservation protocol (added to IEEE Std 802.1Q-2005 as amended by IEEE
34、Std 802.1Qat-2010) and forwarding rules for traffic shaping (added to IEEE Std 802.1Q-2005 as amended by amendment 802.1Qav-2009). This standard builds on and depends on the AVB standards. This standard is relevant in todays entertainment world as more and more entertainment media is being digitally
35、 transported. Streaming audio/video and interactive applications over bridged LANs need to have real-time performance comparable with legacy analog distribution. There is significant end-user and vendor interest in defining a simple yet common IP-based method for handling real-time audio/video suita
36、ble for consumer electronics, professional A/V applications, etc. Although RTPs use of UDP/IP implies that it can be routed between IP subnets, for reasons of simplicity this standard limits its scope to a single IP subnet. 1Information on references can be found in Clause 2. IEEE Std 1733-2011 IEEE
37、 Standard for Layer 3 Transport Protocol for Time-Sensitive Applications in Local Area Networks Copyright 2011 IEEE. All rights reserved. 21.1 Scope This standard specifies the protocol, data encapsulations, connection management and presentation time procedures used to ensure interoperability betwe
38、en audio and video based end stations that use standard networking services provided by all IEEE 802 networks meeting quality of service (QoS) requirements for time-sensitive applications by leveraging the Real-time Transport Protocol (RTP) family of protocols and family of IEEE 802.1 Audio/Video Br
39、idging (AVB) protocols. 1.2 Purpose This standard will facilitate interoperability between stations that stream time-sensitive audio and/or video across bridged and routed LANs providing time synchronization and latency/bandwidth services by defining the packet format and stream setup, control, sync
40、hronization and teardown protocols by leveraging Real-time Transport Protocol (RTP) family of protocols and IEEE 802.1 AVB protocols. 2. Normative references The following referenced documents are indispensable for the application of this document (i.e., they must be understood and used, so each ref
41、erenced document is cited in text and its relationship to this document is explained). For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments or corrigenda) applies. IEEE 802.1AS-2011, IEEE Standard for Lo
42、cal and Metropolitan Area NetworksTiming and Synchronization for Time-Sensitive Applications in Bridged Local Area Networks.2, 3 IEEE Std 802.1Q-2005, IEEE Standard for Local and Metropolitan Area NetworksVirtual Bridged Local Area Networks. IEEE 802.1Qat-2010, IEEE Standard for Local and Metropolit
43、an Area NetworksVirtual Bridged Local Area Networks Amendment 14: Stream Reservation Protocol (SRP). IEEE 802.1Qav-2009, IEEE Standard for Local and Metropolitan Area NetworksVirtual Bridged Local Area Networks Amendment 12: Forwarding and Queuing Enhancements for Time-Sensitive Streams. Real-Time T
44、ransport Protocol (RTP) Parameters: http:/www.iana.org/assignments/rtp-parameters. 3. Definitions For the purposes of this document, the following terms and definitions apply. The IEEE Standards Dictionary: Glossary of Terms present audio sample zero at GPS-traceable time 08:23:17.0000000 PST, prese
45、nt audio sample 96 at GPS-traceable time 8:23:17.002182 PST. In this example, the talkers media clocks relationship to the shared GPS time is communicated to the listener(s) that can then ensure that they are rendering the audio samples at the same rate as the talker. If they did not, their sample b
46、uffers could run out of data or overflow. In addition, the talkers would be capable of rendering the first sample at the correct time (e.g., simultaneously). Rather than transport the IEEE 802.1AS timestamp in every RTP packet, the correlation between IEEE 802.1AS time and the media timestamp is com
47、municated in an RTCP packet extension. Along with the timestamp information the Grand Master information and any time discontinuities are also sent in the RTCP packet. These new RTCP packets containing the necessary clock information are sent periodically over the LAN to ensure RTP media clocks rema
48、in synchronized. In order to derive the relation between the RTP sampling clock and the IEEE 802.1AS clock, at least two RTCP packets containing the above clock synchronization information are sent to the listener(s). Two RTCP packets are required to find the relation between the RTP timestamps and
49、the IEEE 802.1AS timestamps. In order to keep the clocks synchronized between the RTP sampling clock and the IEEE 802.1AS clock, RTCP packet containing the above clock synchronization needs to be sent periodically throughout the life of a stream. In order to avoid the discontinuities associated with UTC, IEEE 802.1AS clock uses the International Atomic Time (TAI) time scale. 6.2 IEEE Std 802.1Qat-2009 This standard defines the Stream Reservation Protocol (SRP) which allows reservation of network resources (bandwidth, with latency bounds) for strea
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