CAN CSA-ISO IEC 8473-5-2001 Information Technology - Protocol for Providing the Connectionless-Mode Network Service Provision of the Underlying Service by ISDN Circuit-Switched B-C.pdf

1、 National Standard of CanadaCAN/CSA-ISO/IEC 8473-5-01(ISO/IEC 8473-5:1997)International Standard ISO/IEC 8473-5:1997 (first edition, 1997-05-01), has been adopted withoutmodification (IDT) as CSA Standard CAN/CSA-ISO/IEC 8473-5-01, which has been approved as a NationalStandard of Canada by the Stand

2、ards Council of Canada.ISBN 1-55324-408-7 December 2001Reference numberISO/IEC 8473-5:1997(E)The Canadian Standards Association (CSA), The Standards Council of Canada is theunder whose auspices this National Standard has been coordinating body of the National Standards system, produced, was chartere

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17、dian Standards AssociationInformation technology Protocol for providing the connectionless-mode networkCAN/CSA-ISO/IEC 8473-5-01 service: Provision of the underlying service by ISDN circuit-switched B-channelsDecember 2001 Canadian Standards Association CSA/1CAN/CSA-ISO/IEC 8473-5-01Information tech

18、nology Protocolfor providing the connectionless-mode network service: Provision ofthe underlying service by ISDNcircuit-switched B-channelsCSA PrefaceStandards development within the Information Technology sector is harmonized with internationalstandards development. Through the CSA Technical Commit

19、tee on Information Technology (TCIT),Canadians serve as the Canadian Advisory Committee (CAC) on ISO/IEC Joint Technical Committee 1 onInformation Technology (ISO/IEC JTC1) for the Standards Council of Canada (SCC), the ISO memberbody for Canada and sponsor of the Canadian National Committee of the

20、IEC. Also, as a member of theInternational Telecommunication Union (ITU), Canada participates in the International Telegraph andTelephone Consultative Committee (ITU-T).This International Standard was reviewed by the CSA TCIT under the jurisdiction of the StrategicSteering Committee on Information T

21、echnology and deemed acceptable for use in Canada. (Acommittee membership list is available on request from the CSA Project Manager.) From time to time,ISO/IEC may publish addenda, corrigenda, etc. The CSA TCIT will review these documents for approvaland publication. For a listing, refer to the CSA

22、Information Products catalogue or CSA Info Update orcontact a CSA Sales representative. This Standard has been formally approved, without modification, bythese Committees and has been approved as a National Standard of Canada by the Standards Council ofCanada.December 2001 Canadian Standards Associa

23、tion 2001All rights reserved. No part of this publication may be reproduced in any form whatsoever without the prior permissionof the publisher. ISO/IEC material is reprinted with permission. Where the words “this International Standard” appearin the text, they should be interpreted as “this Nationa

24、l Standard of Canada”. Inquiries regarding this National Standard of Canada should be addressed to Canadian Standards Association 178 Rexdale Boulevard, Toronto, Ontario, Canada M9W 1R31-800-463-6727 416-747-4044www.csa.caINTERNATIONAL STANDARD ISO/IEC 8473-5 First edition 1997-05-01 Information tec

25、hnology - Protocol for providing the connectionless-mode network service: Provision of the underlying service by ISDN circuit-switched B-channels Technologies de Iinforma tion - Protocole pour la fourniture du service de r b) Network layer; C) service; d) service data unit; e) protocol control infor

26、mation. 32 . Network layer architecture definitions This Recommendation I International Standard makes use of the following terms defined in ISO/IEC 8648: a subnetwork; b) subnetwork dependent convergence protocol; C subnetwork dependent convergence function; d) subnetwork access protocol. 33 . Netw

27、ork layer addressing definitions This Recommendation I International Standard makes use of the following term defined in CCITT Rec. X.213 I ISO/IEC 8348: - subnetwork point of attachment. 4 Abbreviations For the purposes of this Recommendation I International Standard, the following abbreviations ap

28、ply: CLNP Connectionless-mode Network Protocol DCE Data Circuit-terminating Equipment DTE Data Terminal Equipment ES End System IS Intermediate System 2 ITU-T Rec. 1 FL.625 (1996 E) A ISO/IEC 8473-5 : 1997 (E) ISDN PDU PVC QOS SDU SN SNDCF SNDCP SNICP SNAcP SNPA SNCR SNSDU TA TE Integrated Services

29、Digital Network Protocol Data Unit Permanent Virtual Circuit Quality of Service Service Data Unit Subnetwork Subnetwork Dependent Convergence Function Subnetwork Dependent Convergence Protocol Subnetwork Independent Convergence Protocol Subnetwork Access Protocol Subnetwork Point of Attachment Subne

30、twork Connection Reference Subnetwork Service Data Unit Terminal Adapter Terminal Equipment 5 Subnetwork dependent convergence function 51 . General model The general model for providing the underlying service assumed by the protocol in conjunction with a real subnetwork that uses a connectionless s

31、ubnetwork access protocol is as follows. The generation of an SN-UNIT-DATA Request by the CLNP results in the generation of a corresponding subnetwork-specific UN IT-DATA request by the subnetwork dependent convergence function. The receipt of a subnetwork-specific UN IT-DATA indication associated w

32、ith delivery of a connectionless data unit to its destination causes the SNDCF to generate an SN-UNIT-DATA indication to the CLNP. The general model for providing the underlying service assumed by the CLNP in conjunction with a real subnetwork that uses a connection-mode subnetwork access protocol i

33、s as follows. The generation of an SN-UNIT-DATA request by the CLNP causes a connection (logical channel, logical link, or the equivalent) to be made available for the transmission of SN-User-data. If a connection cannot be made available, the SN-UNIT-DATA Request is discarded. The receipt of subnet

34、work-specific PDUs containing SN-User-data causes the SNDCF to generate an SN-UNIT-DATA indication to the CLNP. Where a real subnetwork is designed to use either a connectionless-mode or a connection-mode subnetwork access protocol, the provision of the underlying service assumed by the CLNP is achi

35、eved by using the connectionless-mode alternative. 52 . Subnetwork user data The SN-Userdata is an ordered multiple of octets, and is transferred transparently between the specified subnetwork points of attachment. The underlying service assumed by the CLNP is required to support a service data unit

36、 size of at least 5 12 octets. If the minimum service data unit sizes supported by all of the subnetworks involved in the transmission of a particular PDU are known to be large enough that segmentation is not required, then either the full protocol or the non-segmenting protocol subset may be used.

37、Data received from a subnetwork with protocol identification specifying this protocol (see ITU-T Rec. X.233 I ISO/IEC 8473-l) shall be processed according to this Recommendation I International Standard. NOTE - Data with other protocol identification should be ignored, since it may have been sent by

38、 an implementation supporting additional protocols intended for use with this protocol. ITU-T Rec. X.625 (1996 E) 3 ISO/IEC 8473-5 : 1997 (E) 53 . Subnetwork dependent convergence functions used with ISDN circuit-switched B-channel 5.3.1 The ISDN environment This SNDCF applies when an ISDN B-channel

39、 is used to carry the PDUs as defined in ITU-T Rec. X.233 1 ISO/IEC 8473-1 between systems. In this context a system may be either an End System (ES) or an Intermediate System (IS), as shown in Figure 1. The underlying ISDN service is the 64 kbit/s bearer service as described in Recommendation I.23

40、1. NOTE - The use of more than one B-channel between a pair of systems is not precluded. When more than one B-channel is used, the single link procedures of ISOiIEC 7776 shall be used on each. ES/IS ES/IS TIS07740-96ldOl Figure 1 - ES-to-IS, IS-to-IS, or ES-to-ES directly connected via ISDN Once the

41、 B-channel has been established (see 5.3.2.2 or 5.3.2.3) the requirements of ITU-T Rec. X.623 1 ISO/IEC 8473-4 shall be applied, i.e. the SNDCF for operation over a subnetwork which provides the OS1 Data Link service. The ES or IS may be either a TEl or TE2/TA terminal supporting the ISDN B-channel

42、presenting the protocol stacks at the S- or T- reference point in accordance with the Recommendations and International Standards shown in Figure 2. I Network ISOAEC 8473-l SNDCF for ISDN 4 Q.921 ISOAEC 11575 (Use of ISOAEC 7776 to provide the DL service) ISOAEC 7776 D-channel I .430 or B-channel 1.

43、431 This Recommendation 1 International Standard lTIS07750-96/d02 Figure 2 - Protocol layers at S- and T-reference points 4 ITU-T Rec. X.625 (1996 E) ISO/IEC 8473-5 : 1997 (E) 5.3.2 Procedures for a TEl or TE2/TA This subclause covers the use of semi-permanent or demand access B-channel connections

44、that can be available to the TEl or TE2/TA terminals. NOTE - The use of the D-channel to operate the CLNP is outside the scope of this Recommendation 1 International Standard. The mapping of elements of the CLNS to the protocol and procedures of ISO/IEC 8473 is specified in CCITT Rec. X. 213 1 ISO/I

45、EC 8348. The following subclauses specie the provision required in addition to these mappings by systems attached to the S/T reference points. 5.3.2.1 Additional procedures for a TEl or TE2/TA when using the ISDN B-channel to directly connect to a remote terminal. The ES or IS shall implement at the

46、 S/T reference points the protocol stacks shown in Figure 2. One of the stacks is used to support signalling necessary to establish the ISDN circuit switched connection to the remote terminal, and the other is used to support the CLNP itself. At the physical layer, Recommendation 1.430 shall be used

47、 if the access is via the basic rate interface, and Recommendation I.43 1 shall be used if the access is via the primary rate interface. At the data link layer, Recommendation 4.921 shall be used over the D-channel and ISO/IEC 7776 shall be used over the B-channel after it has been established. At t

48、he network layer, Recommendation Q.93 1 shall be used over the D-channel to convey signalling information to the ISDN for the purposes of ISDN connection establishment, and ISO/IEC 8473 shall be used over the B-channel for information transfer. 5.3.2.2 Semi-permanent B-channel connection ISO/IEC 777

49、6 shall be used in accordance with ISO/IEC 11575 to provide the OS1 Connection-mode Data Link Service. This service may be used either: a) in accordance with ITU-T Rec. X.623 1 ISO/IEC 8473-4 to provide the ISO/IEC 8473 underlying service; or b) in accordance with ISO/IEC 8208 to operate the X.25 packet layer protocol. In this case the ISO/IEC 8473 underlying service shall be provided in accordance with ITU-T Rec