1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 ) TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU).4%2!4%$G0G03%26)#%3G0G0$)4!,.%47/2+G0G0 )3$.G9)3$.G0G053%2G13.%47/2+G0G0).4%2&!#%302)-!29G0G02!4%G0G053%2G13.%47/2+).4%2&!#%)45G134G0G0RecommendationG0G0) (Extract from the “LUEG0“OOK)NOTES1 ITU-T Recommend
2、ation I.421 was published in Fascicle III.8 of the Blue Book. This file is an extract from theBlue Book. While the presentation and layout of the text might be slightly different from the Blue Book version, thecontents 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 atelecommunication administration and a recognized operating agency. ITU 1988, 1993All rights reserved. No part of this publication may be reproduced or utilized in any form or
4、by any means, electronic ormechanical, including photocopying and microfilm, without permission in writing from the ITU.Fascicle III.8 - Rec. I.421 1Recommendation I.421Fascicle III.8 - Rec. I.421PRIMARY RATE USER-NETWORK INTERFACE(Malaga-Torremolinos, 1984)The primary rate user-network interface structures are defined in Recommendation I.412. The detailedspecifications are contained in Recommendations I.431 (layer 1), I.440 and I.441 (layer 2), I.450, I.451 and I.452(layer 3).
