1、 INTERNATIONAL TELECOMMUNICATION UNION D.12 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU GENERAL TARIFF PRINCIPLES MEASUREMENT UNIT FOR CHARGING BY VOLUME IN THE INTERNATIONAL PACKET-SWITCHED DATA COMMUNICATION SERVICE ITU-T Recommendation D.12 (Extract from the Blue Book) NOTES 1 ITU-T Recommend
2、ation D.12 was published in Fascicle II.1 of the Blue Book. This file is an extract from the Blue Book. While the presentation and layout of the text might be slightly different from the Blue Book version, the contents of the file are identical to the Blue Book version and copyright conditions remai
3、n unchanged (see below). 2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. ITU 1988, 1993 All rights reserved. No part of this publication may be reproduced or utilized in any form
4、or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. Fascicle II.1 - Rec. D.12 1 Recommandation D.12 Fascicle II.1 - Rec. D.12 MEASUREMENT UNIT FOR CHARGING BY VOLUME IN THE INTERNATIONAL PACKET-SWITCHED DATA COMMUNICATION SERVI
5、CE (Geneva, 1980) The CCITT , considering the need to define a unit measuring the volume of information transmitted in an international packet-switched data communication service; taking into account the characteristics of packet-switched data communication services, including particularly those def
6、ined in Recommendations X.1 1, X.2 2, X.3 3 and X.25 4; and the definition of data transmission messages, also called “complete packet sequences” 5; unanimously declares the following: (1) definition of segment: the measurement unit used for charging for the volume of information transmitted in a pa
7、cket-switched service is independent of the maximum packet length. It is called a segment and its length is 64 octets1; (2) operating rule: the quantity of chargeable data contained in each message is expressed as a number of segments and is rounded off to the next higher unit. References 1 CCITT Re
8、commendation International user classes of service in public data networks and ISDNs, Rec. X.1. 2 CCITT Recommendation International data transmission services and optional user facilities in public data networks, Rec. X.2. 3 CCITT Recommendation Packet assembly/disassembly facility (PAD) in a public data network, Rec. X.3. 4 CCITT Recommendation Interface between data terminal equipment (DTE) and data circuit terminating equipment (DCE) for terminals operating in the packet mode on public data networks, Rec. X.25. 5 Ibid., 4.3.5. _ 1This number is subject to further study.
