1、- STD-ITU-T RECMN X-LLb-ENGL 199b LiBb2591 Ob3LlLU 501 INTERNATIONAL TELECOMMUNICATION UNION ITU=T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU X.116 (I 0/96) SERIES X: DATA NETWORKS AND OPEN SYSTEM COM M U N I CATI O N Public data networks - Network aspects Address translation registration and r
2、esolution protocol ITU-T Recommendation X. I 16 (Previously CCITT Recommendation) STD-ITU-T RECMN X-lilib-ENGL 177b Lib257li Ob3liYLL LiLi = ITU-T X-SERIES RECOMMENDATIONS DATA NETWORKS AND OPEN SYSTEM COMMUNICATION PUBLIC DATA NETWORKS Services and facilities In terfaces X.l-X.199 X.l-X.19 X.20-X.4
3、9 I Transmission. signalling and switching X.50-X.89 I Maintenance X.150-X. 179 Administrative arrangements Model and notation Service definitions Connection-mode protocol specifications Connectionless-mode protocol specifications PICS proformas Protocol Identification Security Protocols Layer Manag
4、ed Objects Conformance testing General Satellite data transmission systems MESSAGE HANDLING SYSTEMS DIRECTORY OS1 NETWORKING AND SYSTEM ASPECTS OPEN SYSTEM INTERCONNECTION INTERWORKING BETWEEN NETWORKS Networking Efficiency Naming, Addressing and Registration Abstract Syntax Notation One (ASN. 1) Sy
5、stems Management framework and architecture Management Communication Service and Protocol Structure of Management Information Management functions OS1 MANAGEMENT SECURJTY OS1 APPLICATIONS Commitment, Concurrency and Recovery Transaction processing Remote operations OPEN DISTRIBUTED PROCESSING X.180-
6、X. 199 X.200-X.299 X.200-X.209 X.210-X.219 X.220-X.229 X.230-X.239 X.240-X.259 X.260-X.269 X.270-X.279 X.280-X.289 X.290-X.299 x.300-x.399 X.300-X.349 x.350-x.399 x.400-x.499 x.500-x.599 X.600-X.699 X.600-X.629 X.630-X.649 X.650-X.679 X.680-X.699 x.700-x.799 X.700-X.709 X.7 10-X.7 19 X.720-X.729 x.7
7、30-x.799 X.800-X.849 X.850-X.899 X.850-X.859 X.860-X.879 X.880-X.899 x.900-x.999 ForMther details, please refer to ITU-T List of Recommendations. FOREWORD The IT-T (Telecommunication Standardization Sector) is a permanent organ of the International Telecommunication Union (IT). The IT-T is responsib
8、le for studying technical, operating and tariff questions and issuing Recommen- dations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Confrence (WTSC), which meets every four years, establishes the topics for study by the IT
9、-T Study Groups which, in their turn, produce Recommendations on these topics. The approval of Recommendations by the Members of the IT-T is covered by the procedure laid down in WTSC ResolutionNo. 1 (Helsinki, March 1-12, 1993). IT-T Recommendation X.116 was prepared by IT-T Study Group 7 (1993-199
10、6) and was approved under the WTSC Resolution No. 1 procedure on the 5th of October 1996. NOTE In this Recommendation, the expression bbAdministration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. O ITU 1997 All rights reserved. No pa
11、rt of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing fkom the ITU. Recommendation X116 (10/96) 1 1 2 3 4 5 6 7 8 9 10 11 12 STD-ITU-T RECMN X-LLb-ENGL L99b 48b2591 Ob31413 210 =
12、 CONTENTS Introduction Reference Model Definitions . 2.1 2.2 Additional references Definitions 3.1 Reference Model definitions . 3.2 X.25 Definition . 3.3 Additional definitions . Abbreviations . 4.1 Systems . 4.2 Protocol data units 4.3 Miscellaneous . Address Translation Service Model . Overview o
13、fthe protocol . 6.1 The ARE function . 6.2 Overview of Alternative Address Information . 6.3 Overview of redirection information The ARE address DTE Alternative Address Information subset 8.1 Protocol parameters 8.2 Protocol operation . 8.3 Normal Completion procedure . 8.4 Use of Alternative Addres
14、s Information . DTE redirection information subset . 9.1 Invoking Redirection 9.2 Receiving Redirection Information . 9.3 Use of Redirection Information Address Masks . 10.1 Address Mask . ARE procedures . 1 1.1 Processing of Alternative Address Information subset . 11.2 Processing of Redirection su
15、bset Structure and encoding of PDUs 12.1 Parameters . 12.2 PDU Structure . Identical Recommendations 1 International Standards Annex A . Mapping X.116 messages to X.25 packets 11 Recommendation X.116 (10/96) Page 1 1 1 1 1 1 2 2 2 2 2 3 3 4 4 5 5 5 6 6 6 9 9 10 10 10 11 11 11 12 12 13 14 14 18 22 SU
16、MMARY This Recommendation defines a protocol for the exchange of alternative address related information between a DTE and an address resolution entity as defined in Recommendation X.115. This Recommendation complements Recommendation X. 115 which defines the address translation capability in public
17、 data networks. The protocol defined in this Recommendation enables DTEs to register altemative addresses (e.g. addresses in formats other than X.121 or E. 164). The ARE stores the registered information along with the addresses where DTEs are reachable and provides this information when queried by
18、a DTE or a switching system to enable call establishment. . Recommendation X.116 (10/96) 111 STD*ITU-T RECMN X*LLb-ENGL 1776 m 4Bb257L Ob3LliL5 O73 m Recommendation X.116 ADDRESS TRANSLATION REGISTRATION AND RESOLUTION PROTOCOL (Geneva, 1996) 1 Introduction This Recommendation defines a protocol for
19、 the exchange of alternative address related information between a DTE and an Address Resolution Entity. This Recommendation is applicable to: a) b) DTEs which operate according to ISOAEC 8208; Address Resolution Entities which operate according to ISOAEC 8208. This Recommendation does not speciQ an
20、y protocol elements nor algorithms for facilitating routeing and relaying among ARES. Such functions are intentionally outside the scope of this Recommendation. 2 Reference Model Definitions The following Recommendations and other references contain provisions which, through reference in this text,
21、constitute provisions of this Recommendation. At the time of publication, the editions 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
22、of the Recommendations and other references listed below. A list of the cunently valid IT-T Recommendations is regularly published. 2.1 Identical Recommendations I International Standards - IT-T Recommendation X.200 (1994) I ISOhEC 7498-1:1994, Information technology - Open Systems Interconnection -
23、 Basic Reference Model: the Basic Model. IT-T Recommendation X.213 (1995) I ISOAEC 8348:1996, Information technology - Open Systems Interconnection - Network service definition. IT-T Recommendation X.263 (1995) I ISOAEC TR 9577:1996, Information technology - Protocol Identifcation in the Network Lay
24、er. - - 2.2 Additional references - ITU-T Recommendation X.25 (1996), Interface between Data Terminal Equipment PTE) and Data Circuit-terminating Equipment CE) for terminals operating in the packet mode and connected to public data networks by dedicated circuit. ISOiIEC 8208:1995, Information techno
25、logy - Data Communications - X25 Packet Layer Protocol for Data Terminal Equipment. - 3 Definitions 3.1 Reference Model definitions This Recommendation makes use of the following terms defined in Recommendation X.200 I ISOhEC 7498-1: a) Network Layer; b) Network Service Access Point; c) Network Serv
26、ice Access Point Address; Recommendation X.116 (10/96) 1 3.2 3.3 STD*ITU-T RECMN X-LLb-ENGL L77b qBb257L Ob3L4Lb T2T = d) Network Point of Attachment; e) Network Protocol Data Unit; f) Routeing; g) Subnetwork. X25 Definition - Alternative Address. Additional definitions For the purposes of this Reco
27、mmendation, the following definitions apply. 3.3.1 alternative address related information: Information about the alternative address of DTEs attached to a subnetwork defined in terms of the system types, Network Addresses present, Network Entity Titles present, and the correspondence between system
28、s, X.121 or E.164 addresses and potential routes. 3.3.2 connection, indicating an X.121 or E.164 address which could be used to establish such a connection. redirection information: Information supplied when a Call Request fails to achieve establishment of a 3.3.3 address resolution entity: Supplier
29、 of information concerning address translation within a single network. 4 Abbreviations For the purposes of this Recommendation, the following abbreviations apply. 4.1 Systems ARE Address Resolution Entity DTE Data Terminal Equipment 4.2 Protocol data units ECQ-PDU ENC-PDU ESC-PDU ESH-PDU RD-PDU SCC
30、-PDU SCR-PDU SNC-PDU SRN-PDU DTE Configuration Query Protocol Data Unit DTE Notification Complete Protocol Data Unit DTE Connect Protocol Data Unit DTE Hello Protocol Data Unit Redirect Protocol Data Unit ARE Configuration Complete Protocol Data Unit ARE Configuration Response Protocol Data Unit ARE
31、 Notification Complete Protocol Data Unit ARE Received Notification Protocol Data Unit 2 Recommendation X.116 (10/96) STD-ITU-T RECMN X-ILL-ENGL Subnetwork dependent mapping sub-layer (Clause 12) L7b 4b257L Ob3L4L7 7bb W Subnetwork dependent (Clause 12) I b mapping sub-layer 4.3 Miscellaneous Subnet
32、work Access Function (SNAcF) AA BCD NPA PDU QOS SNAcF SNAcP Subnetwork Access Function (SNAcF) I b Subnetwork access protocol (SNAcP) Alternative Address Binary Coded Decimal Network Point ofAttachment (Le. X.121 address or E.164 address) Protocol Data Unit Quality of Service Subnetwork Access Funct
33、ion Subnetwork Access Protocol NPA defined in this Recommendation is referred to as SNPA in ITU-T Rec. X.213 I ISO/IEC 8348. 5 Address Translation Service Model The network layer in the DTE and in the address translation service may be modeled as consisting of three sub-layers (see Figure 1): ARE se
34、rvice sub-layer: The modeling of this sub-layer permits the definition of a peer-peer ARE service function communication in support of the address translation service defined in Recommendation X. 1 15. Subnetwork-dependent mapping sub-layer: This sub-layer operates over the Subnetwork Access Protoco
35、l (SNAcP) and is used to provide the capabilities assumed by the ARE service sub-layer. It permits to decouple the peer-peer communication between ARE service functions from the detailed operation of particular SNAcPs. The realization of this sub-layer may consist simply of a set of rules for manipu
36、lating the network access protocol and may not involve explicit exchange of PCI (Protocol Control Information). The modeling of this sub-layer provides for application of the peer-peer ARE service fnction communication over other subnetworking technologies. For example over a Frame Relay network, a
37、new set of mapping des need to be defined while peer-peer ARE service function communication remains unchanged. Subnetwork Access Protocol (SNAcP): The access protocol in this Recommendation is X.25 protocol, however, the access protocol could be a different protocol (e.g. Frame Relay). Annex A defi
38、nes the mapping applicable to Recommendation X.25. The above subdivision of the network layer into sub-layers is for modeling purposes and should not be interpreted as implying a particular implementation. ARE service sub-layer (Clauses 6-1 1) ARE service sub-layer (Clauses -II) DTE ARE T0725140-5/6
39、01 FIGURE 1X.116 Subdivision of network layer into sub-layers Recommendation X.116 (10196) 3 The ARE function can be realized in a single entity or can be distributed among several logical entities. As illustrated in Figure 2, the model applies irrespective of the location of the entity(ies) providi
40、ng the address translation service (in a DCE, inside the network, in a DTE outside the network). ARE service sub-layer I I 1 Address Translation Messages 4 b ARE service sub-layer Network Layer L I I I Subnetwork dependent mapping sub-layer Subnetwork Access Function (SNAcF) Subnetwork dependent map
41、ping sub-layer Subnetwork Access 4 b Function (SNAcF) Note NOTE - Internal Protocol in case the ARE is inside the network or SNAcP in case the ARE is outside the network. FIGURE 2K.116 Realization of Address Translation service functionality 6 Overview of the protocol The protocol specified in this
42、Recommendation comprises two subsets: a) b) the Redirection Information subset. the Alternative Address (related) Information subset; The functions of the Alternative Address Information subset are: a) b) to enable DTEs to noti an ARE of the existence and reachability of their Alternative Addresses
43、(AAS); to enable DTEs to discover, for certain AAS, the addresses of systems on the network via which communications may potentially be completed. The function of the Redirection Information subset is to enable DTEs which are attempting to establish a connection to be directed to a specific appropri
44、ate address via which the connection should be completed. The two subsets are complementary in that the information obtained from the Redirection Information subset implicitly carries associated Alternative Address related Information, and in that the information obtained from the Alternative Addres
45、s Information subset may be used to derive a suitable address and so avoid the need for use of the Redirection Information subset. The choice of which subset to use to obtain Alternative Address related Information for any individual instance of communication is a local DTE decision, which may be di
46、fferent for different instances of communication and may be varied freely during the DTE operation without impacting the ability to intenvork. 6.1 The ARE function An ARE is an entity which collects Alternative Address related information from DTEs, and which distributes Alternative Address related
47、and redirection information to them. NOTE -An ARE may also interact with Switching Systems but the details of such interactions are outside the scope of this Recommendation. The function of an ARE may be carried out by one or more DTEs or SSs attached to the network. Where the network is one which i
48、tself acts on the X.25 protocol, it is also possible that some or all of the ARE operations may be performed by functions integrated within the network itself. 4 Recommendation X.116 (10/96) STD*ITU-T RECMN X*LLb-ENGL 197b 48b2571 Ob31419 737 rn in order for a DTE to use this protocol, it requires k
49、nowledge of at least one address which can be used to access an ARE. 6.2 The protocol exchanges which constitute the Alternative Address Information subset begin with the DTE establishing an X.25 connection to an ARE by issuing an X.25 Call Request. The first octet of the call user data contains a protocol identifier indicating the protocol defined in this Recommendation. When the ARE accepts the call, the DTE may then transmit to the ARE details of its Alternative Addresses. Once the information concerning all of its Alternative Addresses is transmitted,
