1、 AMERICAN NATIONAL STANDARD FOR TELECOMMUNICATIONS ATIS-1000630.1999(R2015) Broadband ISDN ATM Adaptation Layer for Constant Bit Rate Services Functionality and Specification As a leading technology and solutions development organization, ATIS brings together the top global ICT companies to advance
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15、10036Copyright 2000 by Alliance for Telecommunications Industry SolutionsAll rights reserved.No part of this publication may be reproduced in anyform, in an electronic retrieval system or otherwise,without prior written permission of the publisher.Printed in the United States of AmericaiContentsPage
16、Foreword ii1 Scope . 12 Normative references . 13 Definitions. 24 Abbreviations and acronyms 35 Requirements . 4iiForeword (This foreword is not part of American National Standard T1.630-1999.)This standard defines the Constant Bit Rate ATM Adaptation Layer (CBR AAL) of aBroadband ISDN (B-ISDN). It
17、describes the protocols used by the CBR AAL to sup-port the transfer of unstructured data (i.e., bits) and structured data (i.e., blocks of oc-tets). It addresses the services provided and expected by the CBR AAL, the functionsperformed by the CBR AAL, the interactions of the CBR AAL with the Manage
18、mentPlane, the format and encoding of the CBR AAL protocol data units, CBR AAL opera-tions, and a tutorial of CBR AAL processes and procedures.The current revision of this standard was made to indicate that the American NationalStandard for ATM Adaptation Layer for Constant Bit Rate Services Functio
19、nality andSpecification shall be ITU-T (formerly CCITT) I.363.1, 1996.T1S1.7 will continue to further develop and complete standards in areas where thereare unresolved issues and develop additional standards on B-ISDN in the future.Suggestions for improvement of this standard will be welcomed. They
20、should besent to the Alliance for Telecommunications Industry Standards, 1200 G Street, NW,Suite 500, Washington, DC 20005.This standard was processed and approved for submittal to ANSI by the AccreditedStandards Committee on Telecommunications, T1. Committee approval of this stan-dard does not nece
21、ssarily imply that all committee members voted for its approval.At the time it approved this standard, the T1 Committee had the following members:G. H. Peterson, ChairmanE. R. Hapeman, Vice-ChairmanS. M. Carioti, T1 DisciplinesS. D. Barclay, T1 SecretaryJim Lord, Senior EditorGreg Ratta, Technical E
22、ditorEXCHANGE CARRIERSAmeritech . Fred KujawskiLarry A. Young (Alt.)AT and x is the number of these y cells that leave at the egress of the net-work.In a network element, cell loss ratio is (1 - x/y), where: y is the number of cells that arrive in an interval at theingress of the network element; an
23、d x is the number of these y cells that leave at the egress of the networkelement.3.8 corresponding entities: Peer entities with a lower layer connection among them.3.9 header: Protocol control information located at the beginning of a protocol data unit.3.10 layer entity: An active element within a
24、 layer.3.11 layer function: A part of the activity of the layer entities.3.12 layer service: A capability of a layer or the layers beneath it that is provided to the upper layer entities atthe boundary between that layer and the next higher layer.3.13 layer user data: Data transferred between corres
25、ponding entities on behalf of the upper layer or layermanagement entities for which they are providing services.3.14 peer entities: Entities within the same layer.3.15 point-to-point connection: A connection with only two endpoints.3.16 primitive: An abstract, implementation-independent, interaction
26、 between a layer service user and alayer service provider.3.17 protocol: A set of rules and formats (semantic and syntactic) that determines the communication be-havior of layer entities in the performance of the layer functions.3.18 protocol control information: Information exchanged between corres
27、ponding entities, using a lowerlayer connection, to coordinate their joint operation.3.19 protocol data unit (PDU): A unit of data specified in a layer protocol and consisting of protocol controlinformation and layer user data.3.20 service access point (SAP): The point at which an entity of a layer
28、provides services to its LM entity orto an entity of the next higher layer.3.21 service data unit (SDU): A unit of interface information, the identity of which is perserved from one endof a layer connection to the other.T1.630-199933.22 structured data transfer: The transfer of AAL user information
29、supported by the CBR AAL when theAAL-user data transferred by the AAL is organized into data blocks with a fixed length corresponding to anintegral number of octets.3.23 sublayer: A logical subdivision of a layer.3.24 unstructured data transfer: The transfer of AAL user information supported by the
30、CBR AAL when theAAL-user data transferred by the AAL is not organized into data blocks.3.25 virtual channel connection (VCC): A concatenation of VCLs that extends between the points wherethe ATM service users access the ATM Layer. The points at which the ATM cell payload is passed to, or re-ceived f
31、rom, the user of the ATM Layer (i.e. a higher layer or ATM Manamegent entity) for processing, signi-fying the endpoints of a VCC. VCCs are unidirectional.3.26 virtual channel link (VCL): A means of unidirectional transport of ATM cells between the point where aVCI value is assigned and the point whe
32、re that value is translated or removed. For further details, see T1.627.4 Abbreviations and acronymsAAL ATM Adaptation LayerAALM ATM Adaptation Layer ManagementAIS Alarm Indication SignalANSI American National Standards InstituteATM Asynchronous Transfer ModeB-ISDN Broadband (aspects of) Integrated
33、Service Digital NetworkCBR Constant Bit RateCCITT International Telegraph and Telephone Consultative Committee (now known as ITU-T)CRC Cyclic Redundancy CheckCS Convergence SublayerCSI Convergence Sublayer IndicatorISDN Integrated Service Digital NetworkLOS Loss of SignalPDU Protocol Data UnitPHY Ph
34、ysical LayerQOS Quality of ServiceRTS Residual Time StampSAR Segmentation and Reassembly (Sublayer)SAP Service Access PointSC Sequence CountSDT Structured Data TransferSDU Service Data UnitSN Sequence NumberSNP Sequence Number ProtectionSONET Synchronous Optical NetworkT1.630-19994SP Structure Point
35、erSRTS Synchronous Residual Time StampUDT Unstructured Data TransferVCC Virtual Channel ConnectionVCL Virtual Channel Link5 RequirementsThe American National Standard for ATM Adaptation Layer for Constant Bit Rate Services Functionality andSpecification shall be ITU-T (formerly CCITT) I.363.1, 1996.
