1、 INTERNATIONAL TELECOMMUNICATION UNION ITU-T I.378TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Amendment 1(08/2003) SERIES I: INTEGRATED SERVICES DIGITAL NETWORK Overall network aspects and functions General network requirements and functions Traffic control and congestion control at the ATM Adap
2、tation Layer type 2 Amendment 1: New Appendix IV: Deriving AAL 2 traffic parameters from AAL 2 link characteristics ITU-T Recommendation I.378 (2002) Amendment 1 ITU-T I-SERIES RECOMMENDATIONS INTEGRATED SERVICES DIGITAL NETWORK GENERAL STRUCTURE Terminology I.110I.119 Description of ISDNs I.120I.12
3、9 General modelling methods I.130I.139 Telecommunication network and service attributes I.140I.149 General description of asynchronous transfer mode I.150I.199 SERVICE CAPABILITIES Scope I.200I.209 General aspects of services in ISDN I.210I.219 Common aspects of services in the ISDN I.220I.229 Beare
4、r services supported by an ISDN I.230I.239 Teleservices supported by an ISDN I.240I.249 Supplementary services in ISDN I.250I.299 OVERALL NETWORK ASPECTS AND FUNCTIONS Network functional principles I.310I.319 Reference models I.320I.329 Numbering, addressing and routing I.330I.339 Connection types I
5、.340I.349 Performance objectives I.350I.359 Protocol layer requirements I.360I.369 General network requirements and functions I.370I.399 ISDN USER-NETWORK INTERFACES Application of I-series Recommendations to ISDN user-network interfaces I.420I.429 Layer 1 Recommendations I.430I.439 Layer 2 Recommen
6、dations I.440I.449 Layer 3 Recommendations I.450I.459 Multiplexing, rate adaption and support of existing interfaces I.460I.469 Aspects of ISDN affecting terminal requirements I.470I.499 INTERNETWORK INTERFACES I.500I.599 MAINTENANCE PRINCIPLES I.600I.699 B-ISDN EQUIPMENT ASPECTS ATM equipment I.730
7、I.739 Transport functions I.740I.749 Management of ATM equipment I.750I.759 Multiplexing aspects I.760I.769 For further details, please refer to the list of ITU-T Recommendations. ITU-T Rec. I.378 (2002)/Amd.1 (08/2003) i ITU-T Recommendation I.378 Traffic control and congestion control at the ATM A
8、daptation Layer type 2 Amendment 1 New Appendix IV: Deriving AAL 2 traffic parameters from AAL 2 link characteristics Source Amendment 1 to ITU-T Recommendation I.378 (2002) was agreed by ITU-T Study Group 13 (2001-2004) on 1 August 2003. ii ITU-T Rec. I.378 (2002) /Amd.1 (08/2003) FOREWORD The Inte
9、rnational Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommend
10、ations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. The appr
11、oval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administrat
12、ion“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure e.g. interoperability or applicability) and compliance
13、 with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is req
14、uired of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intelle
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16、owever, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. ITU 2004 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU
17、. ITU-T Rec. I.378 (2002)/Amd.1 (08/2003) 1 ITU-T Recommendation I.378 Traffic control and congestion control at the ATM Adaptation Layer type 2 Amendment 1 New Appendix IV: Deriving AAL 2 traffic parameters from AAL 2 link characteristics Appendix I contains a method for deriving the peak CPS byte
18、rate from the AAL 2 Link Characteristics (ALC) defined in ITU-T Rec. Q.2630.1 for the case of periodic AAL 2 traffic sources. The following is a more general approach that does not rely on the assumption of a periodic traffic pattern: In ITU-T Rec. Q.2630.1, the ALC parameter fields are defined as f
19、ollows (the same definition is valid in ITU-T Rec. Q.2630.2, only the parameter naming was changed from AAL type 2 Link Characteristics (ALC) to Link Characteristics (LC): The maximum CPS-SDU bit rate is defined as the maximum bandwidth, available to the AAL type 2 served user in the specified direc
20、tion. The maximum bandwidth is the maximum ratio of the amount of bits transported during the inter-departure time between two subsequent CPS-SDUs, and that inter-departure time. Allowed values are 0 to 2048 kbit/s. The granularity is 64 bit/s. The average CPS-SDU bit rate is defined as the total ex
21、pected amount of bits transported in the specified direction during the holding time of the connection, divided by the holding time of the connection. The average bit rate is also expected to be valid for the time interval between any two active periods. Allowed values are 0 to 2048 kbit/s. The gran
22、ularity is 64 bit/s. The maximum CPS-SDU size is defined as the largest CPS-SDU size, in octets, allowed to be sent in the specified direction during the holding time of the connection. Allowed values are 1 to 45. The average CPS-SDU size is defined in the specified direction as the expected number
23、of transported octets divided by the number of transported CPS-SDUs during the holding time of the connection. The average CPS-SDU size is also expected to be valid for the time interval between any two active periods. Allowed values are 1 to 45. NOTE 1 All four ALC parameter field definitions above
24、 do not include the CPS packet header of 3 bytes length. For AAL 2 traffic sources with constant CPS-SDU size (maximum CPS-SDU size = average CPS-SDU size = CPS-SDU size), the number of CPS packets per second is at most equal to: sizeSDU-CPSratebitSDU-CPSmaximum8NOTE 2 The ALC rate parameters have u
25、nits of bit/s, while the CPS-SDU parameters have units of bytes. 2 ITU-T Rec. I.378 (2002) /Amd.1 (08/2003) Since each of these CPS packets has a 3-byte CPS header, the following holds for PRcps in case of constant CPS-PDU size: byte388 byte sizeSDU-CPSbit/s rate bit SDU-CPS maximumrate bit SDU-CPS
26、maximumbyte/sPRcps + To be on the safe side, PRcps should be at least as large as the right side of the inequality above. In case that the CPS-SDU size is not constant, using the minimum value of the CPS-SDU size instead of CPS-SDU size in the above inequality would result in a PRcps value that is o
27、n the safe side. However this value for PRcps would be unnecessarily large, because the source cannot send with the minimum CPS-SDU size for long time periods. Also the minimum value of the CPS-SDU size is not provided in the ALC. However, the source could send CPS packets with a CPS-SDU length equa
28、l to the average CPS-SDU size for time periods up to the duration of the connection. Therefore the following formula for an approximate derivation for PRcps from ALC parameters is recommended: byte388 byte sizeSDU-CPS averagebit/s rate bit SDU-CPS maximumrate bit SDU-CPSmaximumbyte/sPRcps += In case
29、 of the sustainable CPS byte rate SRcps, a similar approach can be followed if the CPS token bucket size BScps associated with SRcps is chosen as large as the amount of data sent during one activity period. The following approximate value for SRcps would then be: byte388 byte sizeSDU-CPS averagebit/
30、s rate bit SDU-CPS averagerate bit SDU-CPS averagebyte/sSRcps += Printed in Switzerland Geneva, 2004 SERIES OF ITU-T RECOMMENDATIONS Series A Organization of the work of ITU-T Series B Means of expression: definitions, symbols, classification Series C General telecommunication statistics Series D Ge
31、neral tariff principles Series E Overall network operation, telephone service, service operation and human factors Series F Non-telephone telecommunication services Series G Transmission systems and media, digital systems and networks Series H Audiovisual and multimedia systems Series I Integrated s
32、ervices digital network Series J Cable networks and transmission of television, sound programme and other multimedia signals Series K Protection against interference Series L Construction, installation and protection of cables and other elements of outside plant Series M TMN and network maintenance:
33、 international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits Series N Maintenance: international sound programme and television transmission circuits Series O Specifications of measuring equipment Series P Telephone transmission quality, telephone installations,
34、 local line networks Series Q Switching and signalling Series R Telegraph transmission Series S Telegraph services terminal equipment Series T Terminals for telematic services Series U Telegraph switching Series V Data communication over the telephone network Series X Data networks and open system communications Series Y Global information infrastructure and Internet protocol aspects Series Z Languages and general software aspects for telecommunication systems
