1、STDmITU-T RECMN X-8-ENGL 1774 m 48b2571 Ob20371 L4b m INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU DATA NETWORKS AND OPEN SYSTEM COMMUNICATIONS PUBLIC DATA NETWORKS - SERVICES AND FACILITIES X.8 (07/94) MULTI-ASPECT PAD (MAP) FRAMEWORK AND SERVICE DEFIN
2、ITION ITU-T Recommendation X.8 (Previously “CCITT Recommendation”) FOREWORD The ITU-T (Telecommunication Standardization Sector) is a permanent organ of the International Telecommunication Union (IT). The IT-T is responsible for studying technical, operating and tariff questions and issuing Recommen
3、- dations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topic
4、s. The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1 (Helsinki, March 1-12, 1993). IT-T Recommendation X.8 was prepared by -T Study Group 7 (1993-1996) and was approved under the WTSC Resolution No. 1 procedure on the 1 st July
5、 1994. NOTE In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. O ITU 1994 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, el
6、ectronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. STD*ITU-T RECMN Xmh-ENGL 177V Vhb2571 Ob20373 TI9 = PUBLICDATA NETWORKS Services and Facilities ITU-T X-SERIES RECOMMENDATIONS DATA NETWORKS AND OPEN SYSTEM COMMUNICATIONS X.1-X.19 I Subject are
7、a I Recommendation Series I Transmission, Signalling and Switching Network Aspects X.50-X. 89 X.90-X. 149 1 Interfaces I X.20-X.49 I Maintenance Administrative Arrangements OPEN SYSTEMS INTERCONNECTION X. 150-X. 179 X. 180-X. I99 Model and Notation Service Definitions Connection-mode Protocol SDecif
8、ications x.200-x.209 X.210-X.219 X.220-X.229 Connectionless-mode Protocol Specifications PICS Proformas Protocol Identification Security Protocols Layer Managed Objects Conformance Testing X.230-X.239 X.240-X.259 X.260-X.269 X.270-X.279 X.280-X.289 X.290-X.299 I Mobile Data Transmission Systems I X.
9、350-X.369 I INTERWORKING BETWEEN NETWORKS General x.300-x.349 Management MESSAGE HANDLING SYSTEMS DIRECTORY I SECURITY I X.800-X.849 I X. 370-X. 399 x.400-x.499 x.500-x.599 OSNETWORKING AND SYSTEM ASPECTS Networking X .600-X. 649 Naming, Addressing and Registration X.650-X.679 Abstract Syntax Notati
10、on One (ASN.l) X.680-X.699 OS1 MANAGEMENT x.700-x.799 OS1 APPLICATIONS Commitment. Concurrencv and Recoverv I OPEN DISTRIBUTED PROCESSING I x.900-x.999 X.850-X.859 Recommendation X.8 (07/94) Transaction Processing Remote Owrations i X.860-X.879 X.880-X.899 STD-ITU-T RECMN X-ENGL L77Li = Lidb257L bZ3
11、7Li 755 m CONTENTS Page scope References Definitions Abbreviations . Overview of MAPS 5.1 PAD Aspect Support 5.2 PAD Aspect Default . Common Capabilities . 6.1 MAP Status Inquiry 6.2 Modify MAP with Return . Additional MAP capabilities 7.1 Change MAP capability 7.2 Multi-Session 7.3 Remote MAP Contr
12、ol . Appendix I . An example of the use of a MAP Recommendation X.8 (07/94) 1 1 1 2 2 2 2 4 4 4 5 5 6 7 8 iii STD-ITU-T RECMN X-d-ENGL 1774 48b2571 Ob20375 891 SUMMARY This Recommendation provides the definition and framework for providing a Packet AssemblylDisassembly function (PAD) that supports m
13、ultiple protocols, or ?Aspects?, for access to a Packet Switched Public Data Network (PSPDN). The general framework for providing the multiple protocols is outlined, along with the basic requirements necessary within the PAD to enable the selectiodmodification of the protocol Aspects offered. This R
14、ecommendation on Multi- Aspect PAD (MAP), when implemented along with two or more PAD Aspects, will enable a user to access a PSPDN with one protocol, and to change to another protocol. MAP also brings the concept of simultaneous multiple sessions to the PAD as well. This is the framework specificat
15、ion for MAP. See also the various PAD Aspects for protocol and procedure alternatives supporting MAPS (e.g. Recommendations X.28, X.38, etc.). iv Recommendation X.8 (07/94) STD*ITU-T RECMN X-8-ENGL L99Li LiBb259L 062037b 728 Recommendation X.8 MULTI-ASPECT PAD (MAP) FRAMEWORK AND SERVICE DEFINITION
16、(Geneva, 1994) 1 Scope This Recommendation defines the basic framework and service Aspects of a Multi-Aspect Packet Assembly/Disassembly facility (MAP) in a Public Data Network. A MAP includes any Packet Assembly/Disassembly (PAD) Aspect defined by ITU-T, but is not limited to them. A MAP may also i
17、nclude non-IT-T PAD Aspects, such as Binary Synchronous Communications PADs, SDLC PADs, T3POS PADs, generalized polling PAD (GPAD), et ai. The Recommendation does not specify particular network access methods nor protocol Aspects. 2 References The following ITU-T Recommendations and other references
18、 contain provisions which, through reference in this text, constitute provisions of the Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; ail users of the Recommendation are therefore encouraged to investi
19、gate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of currently valid IT-T Recommendations is regularly published. - Recommendation X.25 (1993), Intelface between Data Terminal Equipment (DTE) and Data Circuit- terminating Equipm
20、ent (DCE) for terminals operating in the packet mode and connected to public data networks by dedicated circuit. - Recommendation X.28 (1993), DTHDCE Intelface for start-stop mode data terminal equipment accessing the Packet Assembly Disassembly Facility (PAD) in a public data network situated in th
21、e same country. - Recommendation X.29 (1993), Procedures for the exchange of control information and user data between a Packet Assembly Disassembly (PAD) facility and a packet mode DTE or another PAD. - Recommendation X.38 (1992), G3 facsimile equipment/DCE intelface for G3 facsimile equipment acce
22、ssing the Facsimile Packet Assembly/Disassembly Facility (FPAD) in a public data network situated in the same country. - Recommendation X.39 (1992), Procedures for the exchange of control information and user data between a Facsimile Packet Assembly/Disassembly Facility (FPAD) and a packet mode Data
23、 Terminal Equipment (DTE) or another FPAD. - Recommendation X.340 (1993), General arrangements for interworking between a Packet Switched Public Data Network (PSPDN) and the international telex network. 3 Definitions For the purposes of this Recommendation, the following definitions apply: access in
24、formation path: The communication link established between a DTE and a MAP. access interface: An interface to the MAP with both physical (e.g. speed, parity) and logical (e and an idle time duration indication wherein the PAD reverts to the default Aspect after the specified number of seconds. These
25、 two additional duration parameter values are considered to be optional. 4 Recommendation X.8 (07/94) STD-ITU-T RECMN X-ENGL 1994 48b2591 Ob20380 157 m Duration Parameter Values TABLE 2Bc.8 Resulting Action Access Information Path Virtual Call The PAD shall revert to the default Aspect upon the clos
26、ing of the AIP. The PAD shall revert to the default Aspect upon clearing of the virtual call. seconds of idle time (Le. no activity) on the PAD, independent of the VC status. All PAD Parameter settings and values set previous to the Modify MAP command signal in the default Aspect remain as set. No c
27、hanges to any values take place due to the new Aspect. Upon entering the new Aspect, the Aspect will obtain all necessary operational parameter values (e.g. speed, character code set, parity) from the previous Aspect. Should said values be inapplicable or unavailable to the new Aspect, default value
28、s, as specified in the reference Recommendations shall be used. Upon receipt of the Modify MAP command signal, the PAD shall confirm the command by sending a Confirm Modify MAP service signai and then transition to the specified PAD Aspect. All PAD Aspects upon entry shall issue an Aspect Entry MAP
29、service signal to indicate successful transition to the new PAD instance. 7 Additional MAP capabilities Additional MAP capabilities may be offered by some Administrations when supporting the MAP functionality. The following capabilities further enhance the benefits and flexibility of the MAP offerin
30、g: - ChangeMAP; - - Remote MAP Control. Multi-session (New Instance support); and 7.1 Change MAP capability A MAP may provide an on-line method for users of dedicated access interfaces to changehpecify the default PAD Aspect. This Change MAP capability is provided to enable users of dedicated MAP ac
31、cess interfaces to control which PAD Aspect is always invoked when the access information path (AIP) is established. This capability to change the default PAD Aspect provides a simple form of customer configuration management. Through a default PAD Aspect will be configured at subscription time, thi
32、s capability allows users of dedicated access interfaces to re-configure the default PAD Aspect after subscription time. The Change MAP command signal is entered to cause the PAD to change the default Aspect of operation. The Change MAP command signal shall support a parameter that indicates the spe
33、cific PAD Aspect that is to be used. Once having confirmed the event (see below concerning Change MAP Verification sequence), the PAD will immediately disconnect the AIP and then change to the new default PAD Aspect. Subsequent establishment of the AIP will then be presented with this PAD Aspect. PA
34、DS supporting the Change MAP capability shall provide a Change MAP Vercatian sequence. The sequence shall provide a request indication-response-confirm sequence to ensure the Change MAP function is desired (vice the Modify MAP command as outlined above in 6.2). Upon receipt of a valid Change MAP com
35、mand signal, the PAD shall seek to confirm the requested change by transmitting a Verify Change MAP service signal to the DTE. The Verify Change MAP service signal shall include the name of the new specified PAD aspect and an indication of the specific access port being Recommendation X.8 (07/94) 5
36、STD-ITU-T RECMN X-8-ENGL 177Li D LiAb2571 Ob20381 075 changed. The DTE must respond with the Confirm Change MAP command signal. Upon receipt of a valid Confirm Change MAP command signal, the PAD will transmit the appropriate Confirm Change MAP service signal, disconnect the AIP and change the defaul
37、t PAD Aspect for that interface. The Change MAP procedure may only be used when a virtual call is not in progress. NOTE - The Change MAP procedure is defined herein to be used on dedicated access interfaces only. Applications of the Change MAP procedure to public ports is for further study. 7.2 Mult
38、i-Session With the introduction of the support of multiple Aspects within a single PAD, the ability to run multiple simultaneous Aspects can be provided. Each Aspect that is running (Le. an Aspect Instance) supports one virtual call. The Multi- session procedures enable the MAP user to open up addit
39、ional Aspects, or instances, without closing the previous instance, without any additional AIPs. Further, Multi-session procedures allow the MAP user to dynamically switch between the open instances, back and forth, at any time. This results in a traditionally single-session user being able to run m
40、ultiple parallel sessions. The Multi-session capability shall be controlled with the following procedures: New Instance Establishment Switch Instance and Close Instance. 7.2.1 New Instance Establishment A MAP shall allowa DTE to start, or open, a new instance of a PAD Aspect without closing the curr
41、ent instance. The New Instance MAP command signal shall enable this function. The New Instance MAP command signal procedures may be used both before a virtual call is set up and while a virtual call is in progress. The procedures for the selection of a different PAD instance are defined in the refer
42、enced Recommendations. The New Instance MAP command signal is entered to cause the PAD to open a new instance of the PAD aspect while maintaining the existing instance and any associated VCs. The New Instance MAP command signal causes a new instance of the same PAD aspect to be opened. All PAD Param
43、eter settings and values set previous to the Modify MAP command signal in the default Aspect remain as set. The new instance PAD aspect opens with the same parameter values as those in the originating Aspect. Once entering the new instance, the DTE operates in total conformance with the capabilities
44、 and functionality provided by that instance. The DTE may change parameter values, in accordance with the referenced Recommendations, within each instance; independent of one another. The DTE may change operational characteristics of each instance, independent of one another. The DTE may even change
45、 aspect types (with the Modify MAP command signal; if supported) independent of one another. Upon receipt of the. New Instance MAP command signal, the PAD shall confirm the command by sending a Confirm New Instance MAP service signal and then open and transition to the specified PAD Aspect. All PAD
46、Aspectsupon entry shall issue an Aspect Entry MAP service signal to indicate successful transition to the new PAD instance. 7.2.2 Switch Instance In order to switch between PAD instances, (as opened with the New Instance MAP command signai defined above) the Switch MAP command signal is provided. Th
47、e Switch MAP commund signal procedures may be used at any time after a New Instance MAP command signai has been issued, and before a Close Instance MAP command signal has been issued. The procedures for using the Switch MAP command signal to move between instances are found in the referenced Recomme
48、ndations. Should the instances being switched between be of different type Aspects (such as due to the use of the Modify MAP command signal), the procedure for switching out of an instance shall be governed by the Aspects referenced Recommendation. 6 Recommendation X.8 (07/94) STD-ITU-T RECMN XaB-EN
49、GL 1774 48b259L 0b20182 TZL 7.2.3 Close Instance A MAP shall enable a DTE to stop or close, an instance of a PAD Aspect without closing any other instance, nor the AIP. The Close Instance MAP command signal shall provide this function. The Close Instance MAP command signal procedures may be used both before a virtual call is set up and while a virtual call is in progress. The procedures for handling any open or pending VC when a Close Instance MAP command signal is issued shall be identical to those procedures outlined in the referenced Recommendations concerning disc
