1、ANSI INCITS 189-1991 (R2002) (formerly ANSI X3.189-1991 (R1997)for Information Systems Interface betweenData Terminal Equipment (DTE) andData Circuit-Terminating Equipment(DCE) for TerminalsOperating in the Packet Mode andAccessing a Packet-SwitchedPublic Data NetworkThrough Switched AccessAmericanN
2、ationalStandardApproval of an American National Standard requires review by ANSI that therequirements for due process, consensus, and other criteria for approval havebeen met by the standards developer.Consensus is established when, in the judgment of the ANSI Board of StandardsReview, substantial a
3、greement has been reached by directly and materiallyaffected interests. Substantial agreement means much more than a simplemajority, but not necessarily unanimity. Consensus requires that all views andobjections be considered, and that a concerted effort be made toward theirresolution.The use of Ame
4、rican National Standards is completely voluntary; their existencedoes not in any respect preclude anyone, whether he has approved the standardsor not, from manufacturing, marketing, purchasing, or using products, processes,or procedures not conforming to the standards.The American National Standards
5、 Institute does not develop standards and will inno circumstances give an interpretation of any American National Standard.Moreover, no person shall have the right or authority to issue an interpretation ofan American National Standard in the name of the American National StandardsInstitute. Request
6、s for interpretations should be addressed to the secretariat orsponsor whose name appears on the title page of this standard.CAUTION NOTICE: This American National Standard may be revised orwithdrawn at any time. The procedures of the American National StandardsInstitute require that action be taken
7、 periodically to reaffirm, revise, or withdrawthis standard. Purchasers of American National Standards may receive currentinformation on all standards by calling or writing the American National StandardsInstitute.Published byAmerican National Standards Institute11 West 42nd Street, New York, New Yo
8、rk 10036Copyright 1992 by Information Technology Industry Council (ITI)All rights reserved.No part of this publication may be reproduced in anyform, in an electronic retrieval system or otherwise,without prior written permission of ITI, 1250 Eye Street NW,Washington, DC 20005.Printed in the United S
9、tates of AmericaApproved June 4, 1991American National Standards Institute, Inc.American National Standardfor Information Systems Interface between Data Terminal Equipment (DTE)and Data Circuit-Terminating Equipment (DCE)for Terminals Operating in the Packet Mode andAccessing a Packet-Switched Publi
10、c Data NetworkThrough Switched AccessANSISecretariatComputer and Business Equipment Manufacturers AssociationX3.189-1991iiContentsPageForeword iii1 Scope. 12 Normative references 13 Requirements . 2AnnexesA DTE-to-DTE operation. 6B Modem characteristics facility 7C Acronyms. 8iiiiiForeword (This for
11、eword is not part of American National Standard X3.189-1991.)This standard was developed by Task Group X3S3.7, Public Digital NetworkAccess, in close cooperation with the International Telegraph and Tele-phone Consultative Committee (CCITT). Task group X3S3.7 started its workon public data network a
12、ccess protocols in 1973 and contributed to theinternational work of CCITT in this area. Initial access to public datanetworks was by way of dedicated lines. Work in CCITT on switched accessto public data networks started in 1983 and resulted in the adoption ofRecommendation X.32 in 1984. Task Group
13、X3S3.7 was responsible forsignificant input to this work through the U.S. CCITT Study Group D, whichis responsible for the U.S. contributions to the CCITT in the area of datacommunications. To meet the need for switched access to public datanetworks to meet the unique requirements of the U.S. enviro
14、nment, the taskgroup determined that Recommendation X.32 should serve as the basis foran American National Standard for such applications. The draft proposedAmerican National Standard was submitted to ANSI Technical CommitteeX3S3 to start the approval process according to ANSI procedures. Theprocess
15、 was successfully completed, resulting in ANSI X3.189-1991.This standard contains three annexes. Annexes A and B are normative, andare considered part of this standard. Annex C is informative, and is notconsidered to be part of this standard.Suggestions for the improvement of this standard will be w
16、elcome. Theyshould be addressed to the Computer and Business Equipment Manufactur-ers Association, 311 First Street, NW, Suite 500, Washington, DC, 20001.This standard was proposed and approved for submittal to ANSI by Ameri-can National Standards Committee on Information Processing Systems, X3.Comm
17、ittee approval of the standard does not necessarily imply that allcommittee members voted for its approval. At the time it approved thisstandard, the X3 Committee had the following members:Richard Gibson, ChairmanDonald C. Loughry, Vice-ChairmanJoanne Flanagan, Administrative SecretaryOrganization R
18、epresented Name of RepresentativeAllen-Bradley Company Ronald R. ReimerAmerican Library Association Paul PetersAmerican Nuclear Society Geraldine C. MainAMP, Inc. . Edward KellyPatrick Lannon (Alt.)Apple Karen HigginbottomAssociation of the Institutefor Certification of Computer Professionals (AICCP
19、) Kenneth ZemrowskiEugene M. Dwyer (Alt.)AT data link layer control procedure; packet layer procedures; specifications for and support of X.32 op-tional user facilities; and specifications for calling and called ad-dresses.3.1 Physical layerAt the physical layer, the provisions of section4 of CCITT
20、Recommendation X.32 apply, sub-ject to the following.3.1.1 Physical interfaceFor a description of the physical layer interfacefor the case of ISDN transparent circuit con-nection, see CCITT Recommendation X.31.For establishment, maintenance, and dises-tablishment of a switched access path betweena D
21、TE and a PSPDN by way of a PSTN, thephysical layer interface shall be described inthe following points of this section.2on the general switched telephone networkand on point-to-point 2-wire leased telephone-type circuits 2), 3)CCITT Recommendation V.24 (1988), List ofdefinitions for interchange circ
22、uits between dataterminal equipment and data circuit-terminat-ing equipment 2), 3)CCITT Recommendation V.25 (1988), Auto-matic answering equipment and/or parallelautomatic calling equipment on the generalswitched telephone network including proce-dures for disabling the echo control devices forboth
23、manually and automatically establishedcalls 2), 3)CCITT Recommendation V.25bis (1988), Au-tomatic calling and/or answering equipment onthe general switched telephone network(GSTN) using the 100-series interchange cir-cuits 2), 3)CCITT Recommendation V.28 (1988), Electri-cal characteristics for unbal
24、anced double-cur-rent interchange circuits 2), 3)CCITT Recommendation V.32 (1988), A familyof 2-wire, duplex modems operating at datasignaling rates of up to 9600 bit/s for use on thegeneral switched telephone network and onleased telephone-type circuits 2), 3)CCITT Recommendation V.35 (1984), Datat
25、ransmission at 48 kilobits per second using60-108 kHz group band circuits 2), 3)CCITT Recommendation V.54 (1988), Looptest devices for modems 2), 3)CCITT Recommendation X.1 (1988), Interna-tional user classes of service in public datanetworks and integrated services digital net-works 2), 3)CCITT Rec
26、ommendation X.2 (1988), Interna-tional data transmission services and optionaluser facilities in public data networks. 2), 3)CCITT Recommendation X.10 (1988), Catego-ries of access for data terminal equipment(DTE) to public data transmission services pro-vided by PDN s and/or ISDN through terminalad
27、apters 2), 3)CCITT Recommendation X.25 (1988), Inter-face between data terminal equipment (DTE)and data circuit-terminating equipment (DCE)for terminals operating in the packet mode andconnected to public data networks by dedi-cated circuit 2), 3)3ANSI X3.189-19913.1.2 Modem characteristicsPublic Da
28、ta Networks may choose to offermodem characteristics operating in the syn-chronous mode in accordance with any or all ofthe following:a) 2400/1200 bits/s V.22 bits, modes (i) or(iii)b) 9600/4800 bits/s V.32c) 300, 1200 bits/s Bell 212AThe national default modem characteristic forunregistered dial-ou
29、t is V.22 bis.3.1.3 Procedures for full duplex opera-tional phasesProcedures for full duplex operation shall be inaccordance with 4.3.2 of CCITT Recommen-dation X.32.3.2 Data link layerThis section specifies the data link layer proce-dures that are employed to support switchedaccess data interchange
30、 between a DCE and aDTE. The provisions of section 5 of CCITTRecommendation X.32 apply, subject to thefollowing.3.2.1 Compatibility with the HDLC bal-anced classes of procedureThe switched access data link layer proce-dures defined in this standard use the prin-ciples and terminology of the High-Lev
31、el DataLink Control (HDLC) Procedures. (See 5.1.1 ofCCITT Recommendation X.32 and 2.2., 2.3,and 2.4 of CCITT Recommendation X.25.)3.2.2 Data link proceduresThe single link procedure (SLP) shall be sup-ported.3.2.3 Data link layer address assignmentData link layer address assignment shall be inaccord
32、ance with the specifications in 2.4.2 ofCCITT Recommendation X.25, in which thedata link layer address assignment dependson the roles of the equipment as DTE and DCEsuch that the DCE transmits to the DTE theaddress A in command frames and the addressB in response frames and the DTE does theopposite
33、(i.e., transmits to the DCE address Bin command frames and address A in responseframes).3.3 Packet layerThe formats and the procedures at the packetlayer shall be in accordance with sections 3, 4,35, 6, and 7 of CCITT Recommendation X.25and section 6 of CCITT Recommendation X.32,subject to the follo
34、wing.3.3.1 Use of registration packets for iden-tification of DTE and/or DCE and for con-veyance of X.32 optional user facilitiesThe use of registration packets for identifica-tion or for the conveyance of X.32 optional userfacilities, or for both purposes, shall be inaccordance with 6.2 of CCITT Re
35、commenda-tion X.32.3.3.2 Identification and authentication ofthe DTE using the NUI Selection facility incall set-up packetsThe use of the NUI Selection facility for identi-fication and authentication shall be in accor-dance with 6.3 of CCITT Recommendation X.32.3.4 Identification protocolThe procedu
36、res for the use of the identificationprotocol shall be in accordance with section 7of CCITT Recommendation X.32.3.5 Functional aspectsThe functional aspects for dial-in and dial-outoperation shall be in accordance with section 2of CCITT Recommendation X.32, subject tothe following.3.5.1 Support of s
37、ervice for dial-in-by-the-DTE operationNetworks shall support the provision ofnonidentified service and identified service fordial-in-by-the-DTE operation.3.5.2 Transmission facilityThe transmission facility is duplex. Support ofhalf-duplex operation is not addressed by thisstandard.3.5.3 Support of
38、 identification by means ofNUI for dial-inNetworks shall support identification by meansof the NUI Selection facility in call requestpackets. This method shall be supported forthe dial-in-by-the-DTE. Networks shall provideidentified service to a DTE identified by meansof the NUI Selection facility i
39、n accordance with2.3.2.2 and 3.4 of CCITT RecommendationX.32. Other methods of DTE identification inaccordance with 2.4 of CCITT Recommenda-tion X.32 are optional. Networks may option-ally offer NUI Override with a user selectable4ANSI X3.189-1991X.25 subscription set as part of identified ser-vice.
40、 This shall be done by means of the NUISelection facility in the call request packet inaccordance with 2.3.2.2 and 6.3 of CCITT Rec-ommendation X.32.3.5.4 Optional aspects of X.32Additionally, those services/attributes definedas optional in CCITT Recommendation X.32will be optional within this stand
41、ard.3.6 Service attributes“Attributes“ are defined to describe each as-pect of switched access service. However, thevalues of the attributes do not necessarily in-clude all capabilities offered to PSPDN usersthat access the PSPDN via a leased line. Foreach DTE service, (i.e., Nonidentified, Identi-f
42、ied, and Customized), each attribute is eithernot provided, or if provided, is set to a defaultvalue specified by the network or set to a valueby the user from a set of values provided by thenetwork. Not all of these attributes may beoffered by the network.3.6.1 DTE identityDTE identity is the ident
43、ity agreed upon be-tween the user and the Public Data Network.Support of DTE identity shall be in accordancewith 2.2.1 and 3.1.1 of CCITT Recommenda-tion X.32.3.6.2 DTE identification methodsThe DTE identification method defines themethod used for establishing the DTE identity.CCITT Recommendation X
44、.32 describes fourmethods for DTE identification. This standard,for operation with a PSPDN, supports identifi-cation provided by the public switched net-work, identification by means of packet layerregistration procedures, and identification bymeans of the NUI Selection facility. For DTE-to-DTE oper
45、ation, see annex A. DTE identifi-cation methods supported by this standardshall be in accordance with 2.4 and 3.1.2 ofCCITT Recommendation X.32.a) DTE identification using NUI Selection facilityThe NUI Selection facility is used in the callrequest packet to identify the calling DTE inthe case of dia
46、l-in-by-the-DTE. The NUI Se-lection facility is used in the call acceptedpacket to identify the called DTE in the caseof dial-out-by-the-PSPDN.NOTE Should more than one network be ca-pable of performing the dial-out-by-the-PSPDNto a DTE, the DTE may not be able to determinewhat format of NUI in the
47、NUI Selection facility toreturn in the call accepted packet.b) Packet layer registrationDTE identification is carried in Registrationpackets exchanged by the DTE and thePSPDN prior to virtual call procedures, inboth dial-in-by-the-DTE and dial-out-by-the-PSPDN cases.c) Provided by the PSNDepending o
48、n the availability of suitablesignaling between the PSN and PSPDN, thePSN supplies the calling DTE identificationin the case of dial-in-by-the-DTE. In thecase of dial-out-by-the-PSPDN, the DTEidentity is based on the information passedto the PSN to establish the dial-out-by-the-PSPDN operation.3.6.3
49、 DTE addressA DTE address is assigned by the network fora given DTE identity and is derived from theDTE identification provided to the PSPDN. TheDTE address may be used as the calling ad-dress of the dial-in DTE delivered to the calledDTE, as described in 2.2.1 (a) and 3.1.3 ofCCITT Recommendation X.32. When the DTEhas both a registered address and a DTE ad-dress, the DTE address value shall be thesame as the DTEs registered address andshall be an X.121 International Data Numberfrom the PSPDN numbering plan (i.e., DNIC +NTN). In the case that the DTE does no
