1、INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU X.115 (04/95) DATA NETWORKS AND OPEN SYSTEM COMMUNICATIONS PUBLIC DATA NETWORKS - NETWORK ASPECTS DEFINITION OF ADDRESS TRANSLATION CAPABILITY IN PUBLIC DATA NETWORKS ITU-T Recommendation X.115 (Previously “C
2、CIlT Recommendation”) ITU-T RECflN*X*LLS 95 4862571 0603233 327 = FOREWORD The ITU-T (Telecommunication Standardization Sector) is a permanent organ of the International Telecommunication Union (ITU). The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recomme
3、n- 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 topi
4、cs. 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.115 was prepared by ITU-T Study Group 7 (1993-1996) and was approved under the WTSC Resolution No. 1 procedure on the 10t
5、h of April 1995. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. O IT 1995 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any
6、means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. ITU-T RECMN*X-LLS 95 4862593 Ob03234 263 Subject area PUBLIC DATA NETWORKS ITU-T X-SERIES RECOMMENDATIONS DATA NETWORKS AND OPEN SYSTEM COMMUNICATIONS (February 1994) ORGANIZATION OF X-
7、SERIES RECOMMENDATIONS Recommendation Series Services and Facilities Interfaces X. 1 -X. 19 X.20-X.49 I Transmission, Signalling and Switching I X.50-X.89 I Network Aspects Maintenance _ _ X.90-X.149 X. 150-X.179 Administrative Arrangements OPEN SYSTEMS INTERCONNECTION I Model and Notation I X.200-X
8、.209 I X. 180-X. 199 I Service Definitions Connectionless-mode Protocol Specifications PICS Proformas 1 X.210-X.2 19 X.230-X.239 X.240-X.259 I Connection-mode Protocol Specifications I X.220-X.229 I Security Protocols Layer Managed Objects X.270-X.279 X.280-X.289 I Protocol Identification I X.260-X.
9、269 I INTERWORKING BETWEEN NETWORKS General X.300-X.349 I Conformance Testing I X.290-X.299 I Management MESSAGE HANDLING SYSTEMS X.370-X.399 X.400-X.499 I Mobile Data Transmission Systems I X.350-X.369 I Naming, Addressing and Registration Abstract Syntax Notation One (ASN. 1) X.650-X.679 X.680-X.6
10、99 X.500-X.599 DIRECTORY OS1 NETWORKING AND SYSTEM ASPECTS OS1 MANAGEMENT SECURITY I Networking I X.600-X.649 I X.700-X.799 X.800-X. 849 Commitment, Concurrency and Recovery Transaction Processing X.850-X.859 X.860-X.879 I OS1 APPLICATIONS I I Remote Operations OPEN DISTRIBUTED PROCESSING X. 880-X.
11、899 X.900-X.999 - ITU-T RECMN*X.LLS 95 4862573 Ob03235 LTT = CONTENTS References Definitions Abbreviations . Address Translation Service . Address Translation Service overview . Operation of Address Translation Service . 6.1 Functions within the networks 6.2 Requirements on DTEs . 6.3 Information co
12、llection during the registration phase 6.4 Information dissemination Service capabilities . 7.1 N-to-1 translation 7.2 l-to-N translation 7.3 7.4 Time-of-day translation Global significance for alternative address . Appendix I . Provision of Address Translation Service In PSPDN environments Appendix
13、 II - Mapping applications into Address Translation Service Appendix III - A Protocol for registration of alternative address related information . Appendix IV - Protocol for Dissemination of Information between Different ARES Recommendation X.115 (04/95) Page 1 1 2 3 5 6 6 8 8 8 8 8 9 9 9 11 12 14
14、14 1 ITU-T RECflN*X.LLS 75 4862571 0603236 036 = SUMMARY This Recommendation provides definition of the address translation service, the service provided to its customers, the functions at the network interface and functions within the network when providing this service. The address translation ser
15、vice provides customers the ability to use addresses in formats other than X.121 or E.164 (e.g. user friends addresses like mnemonic addresses, etc.). The addresses can be any of the alternative addresses defined in Recommendation X.25. The network will translate the address in the Call Request pack
16、et to the desired address to complete the call. 11 Recommendation X.115 (04195) ITU-T RECMN*X-LLS 95 4Ab2591 Ob03237 T72 INTRODUCTION This Recommendation provides a definition of the address translation service, the services provided to its customers, the functions at the network interface and the f
17、unctions within the network when providing the service. Recommendation X.121 specifies the numbering plan for Public Data Networks (PDNs), Recommendation E. 164 specifies the numbering plan for the Integrated Services Digital Network era. Recommendation X. 122E. 166 defines the general procedures ap
18、plicable to numbering plan interworking between ISDNs and PSPDNs; ISDNs and PSTNs; and PSPDNs and PSTNs. “A DTE on a PDN is identified by an international data number, which consists of the Data Network Identification Code (DNIC) of the PDN, followed by Network Terminal Number (NTN) of the called DT
19、EDCE interface, or the Data Country Code (DCC) followed by the National Number.” Recommendation X.25 allows the called DTE address to conform to the formats described in Recommendations X.121, Recommendation E. 164 or an alternative address. Recommendation X.25 specifies a set of Altenarive Addressi
20、ng facilities that enables a calling DTE to use an alternative address to identity the called DTE when establishing a virtual call. An alternative address is defined as one that does not conform to the formats defined in Recommendations X.121 and X.301. The altemative addresses are for example, OS1
21、NSAP address, MAC address, etc. In addition, Recommendation X.25 includes Call Deflection and Call Redirection facilities. Recommendation X.35 presents different PSPDNPSPvtDN interworking routing alternatives. Among the many alternatives that are discussed in X.35, the most relevant routing strategy
22、 is the case where routing is based on a non- X.121 PSPvtDN DTE Address. This is because the addresses assigned to DTEs on the PSPvDN need not be from the PSPDN numbering plan. The addresses assigned to DTEs in PSPvtDN can be an OS1 NSAP address or from a PSPvtDN addressing plan. The PSPDN in this c
23、ase may desire to offer a capability to route the call either on the PSPvtDN numbering plan or on the OS1 NSAP address rather than requiring “two stage dialling”. This Recommendation defines the service that can be provided by PSPDNs to its customers (i.e. DTEs or PSPvtDNs), the requirements on DTEs
24、 when using this service and the functions that must be provided in PSPDNs to offer such a service. This Recommendation does not specify the interface specifications or the protocol elements that would be used to provide the address translation service. . Recommendation X.115 (04/95) 111 Recommendat
25、ion X.115 DEFINITION OF ADDRESS TRANSLATION CAPABILITY IN PUBLIC DATA NETWORKS (Geneva, 199.5) 1 References The following Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editi
26、ons indicated were valid. All Recommendations and other references are subject to revision: all users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently v
27、alid IT-T Recommendations is regularly published. , - - CCITT Recommendation E.164 (1991), Numbering plan for the ISDN era. CCITT Recommendation T.50 (1992), International Reference Alphabet (IRA - Information technology - 7-bit coded character set for information interchange. ITU-T Recommendation X
28、.25 (1993), Inteflace between Data Terminal Equipment (DTE and Data Circuit-terminating Equipment (DCE) for terminals operating in the packet mode and connected to public data networks by dedicated circuit. CCITT Recommendation X. 121 (1992), International numbering plan forpublic data networks. CCI
29、TT Recommendation X. 122E. 166 (1 992), Numbering plan interworking for the E. 164 and X. 121 numbering plans. CCITT Recommendation X.213 (1992) ISOIEC 8348:( 1993), Information technology - Open Systems Interconnection - Network service definition. ITU-T Recommendation X.301 (1993), Description of
30、the general arrangements for call control within a subnetwork and between subnetworks for the provision of data transmission services. ISOAEC 646: 199 1, Information technology - IS0 7-bit coded character set for information interchange. ISOAEC TR 9575: 1990, Information technology - Telecommunicati
31、ons and information exchange between systems - OSI Routing Framework. ISOAEC 10030: 1990, Information technology - Telecommunications and information exchange between systems - End System Routing Information Exchange Protocol for use in conjunction with IS0 8878. ISOAEC 10039:1991, Information techn
32、ology - Open Systems Interconnection - Local area networks - Medium Access Control (MAC) service definition. ISOAEC 10747: 1994, Information technology - Telecommunications and information exchange between systems - Protocol for exchange of inter-domain routing information among intermediate systems
33、 to support forwarding of IS0 8473 PDUs. - - - - - - - - - - 2 Definitions For the purposes of this Recommendation, the following definitions apply: 2.1 address when the called address specified is not an X.121E.164 address. Address Translation Service: A service that enables the network to route ca
34、lls to the proper X.121E.164 2.2 single organization or administrative authority. 2.3 at least one inter-domain link attached to it, and may optionally have intra-domain links attached to it. Administrative Domain: A collection of End Systems, Intermediate Systems, and subnetworks operated by a Bord
35、er intermediate System: An Intermediate System that runs the protocol specified in ISOAEC 10747, has Recommendation X.115 (04/95) I ITU-T RECNN*X*LLS 95 = 4862593 Ob03239 845 = 2.4 the functions of the Network Layer and the layers above the Network Layer. 2.5 different Administrative Domains. 2.6 2.
36、7 Intermediate System. 2.8 to a Network service user by the Network service provider. 2.9 Service Access Point. End System: An abstraction of a real system which fulfills the requirements of an open system and includes Inter-domain Link: A real (physical) or virtual (logical) link between Border Int
37、ermediate Systems in Intermediate System: An abstraction of a real system providing a network-relay function. Network Entity Title: A name that is used to identify unambiguously a Network entity in an End System or Network Service Access Point (NSAP); NSAP: A point at which the OS1 Network service i
38、s made available NSAP address: The information that the OS1 Network service provider needs to identify a particular Network 2.10 which can be used to interconnect real systems for purposes of communication. 2.11 which the entity is attached into a path by which the entity can be reached. 2.12 proced
39、ures and which is wholly contained within a single Administrative Domain. 2.13 Subnetwork: An abstraction of a real subnetwork. 2.14 Subnetwork address: Refers to the point at which a real End System, real subnetwork, or interworking unit is attached to a real subnetwork, or to the point at which th
40、e subnetwork service is offered within an End System or Intermediate System. Real subnetwork: A collection of equipment and physical media which forms an autonomous whole and Routing: A function within a layer which translates the title of an entity or the service-access-point-address to Routing dom
41、ain: A set of End Systems and Intermediate Systems which operate according to the same routing 3 Abbreviations For the purposes of this Recommendation, the following abbreviations apply: ARE BIS DNIC DCE DTE ES ESH IDRP IS ISDN ISH LAN MAC NA NET NLRI NPDU NSAP NTN os1 Address Resolution Entity Bord
42、er Intermediate System Data Network Identification Code Data Circuit-terminating Equipment Data Terminal Equipment End System End System Hello Inter Domain Routing Protocol Intermediate System Integrated Service Digital Network Intermediate System Hello Local Area Network Medium Access Control Netwo
43、rk Address Network Entity Title Network Layer Reachability Information Network Protocol Data Unit Network Service Access Point Network Terminal Number Open Systems Interconnection Recommendation X.115 (04195) PDU PSPDN PSPvtDN PDN PSTN RD RDC RDI SNPA Protocol Data Unit Packet Switched Public Data N
44、etwork Packet Switched Private Data Network Public Data Network Public Switched Telephone Network Routing Domain Routing Domain Confederation Routing Domain Identifier Subnetwork Point of Attachment 4 Address Translation Service The Address Translation Service depicted in Figure 1 shows a DTE that w
45、ishes to communicate with another DTE using the alternative address in the call request packet) which is resolved by an entity called the Address Resolution Entity (ARE) into an address that is consistent with the format specified in Recommendations X.121 or E.164. Network Aiternative Address B1 of
46、Terminal E3 in Call Address Resolution Terminal A B1 trarslaiei to b by ARE Terminal B TO71963094dol X121 or E.1W Address of Terminal B FIGURE 1X.115 Address Translation Service The address translation service depicted in Figure 1 shows the service as a single logical entity (that is, the address re
47、solution entity). In practice, the address translation entity may be single or distributed, and may reside inside or outside of a network. The address resolution entity (or address resolution entities when distributed) may be on the same network as the DTEs accessing it or on different networks. Fig
48、ures 2, 3 and 4 provide some implementation examples. These examples are not meant to be exhaustive and other implementations are possible. ) The use of X.25 Call Request Packets, etc. is for illustrative purposes only. This Recommendation is equally applicable to other Public Data Network environme
49、nts. Recommendation X.115 (04/95) 3 ITU-T RECflN*X=LLS 95 4862593 Ob03243 4T3 The address translation service may require an inter-networking capability to allow address resolution entities on separate networks to communicate with each other as depicted in Figure 4. The communication between various address resolution entities in different networks is provided in such a manner that the DTEs perceive the service as being provided by a single logical entity. FIGURE 2K.115 Address Translation Service (address res
