1、CCITT RECMN*Iv4L3 (f?EV*L) 93 4862.591 0580792 044 INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU INTEGRATED SERVICES DIGITAL NETWORK (ISDN) ISDN USER-NETWORK INTERFACES 1.41 3 (03/93) B-ISDN USER-NETWORK INTERFACE ITU-T Recommendation 1.41 3 (Previously
2、“CCIlT Recommendation”) CCITT RECMN*I-413 (REV*1) 93 m 4862593 0580793 TAO m FOREWORD The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the International Telecom- munication Union. The ITU-T is responsible for studying technical, operating and tariff questions and issu
3、ing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, established the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on t
4、hese topics. ITU-T Recommendation 1.413 was revised by the ITU-T Study Group XVIII (1988-1993) and was approved by the WTSC (Helsinki, March 1-12, 1993). NOTES 1 As a consequence of a reform process within the International Telecommunication Union (ITU), the CCITT ceased to exist as of 28 February 1
5、993. In its place, the ITU Telecommunication Standardization Sector (ITU-T) was created as of 1 March 1993. Similarly, in this reform process, the CCIR and the IFRB have been replaced by the Radiocommunication Sector. In order not to delay publication of this Recommendation, no change has been made
6、in the text to references containing the acronyms “CCITT, CCIR or IFRB” or their associated entities such as Plenary Assembly, Secretariat, etc. Future editions of this Recommendation will contain the proper terminology related to the new ITU structure. 2 telecommunication administration and a recog
7、nized operating agency. In this Recommendation, the expression “Administration” is used for conciseness to indicate both a O ITU 1993 All rights reserved, No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and micro
8、film, without permission in writing from the ITU. CCITT RECMN*I*433 (REVU11 93 I 4862593 0580794 937 CONTENTS Page 1 Introduction . 2 Reference configuration at the user-network interface 2.1 Functional groups and reference points . 2.2 Examples of physical realizations 2.3 2.4 Relationship between
9、ISDN in terfaces . 2.5 Application of B-ISDN model to functional groups . Basic characteristics of the interfaces at TB and SB reference points . 3 Physical iayer information flows and interface functions Relation with other sublayers or entities 3.1 3.2 Modes of operation . 3.3 Interface function U
10、NI related OAM functions . 4 Annex A - Alphabetical List of abbreviations used in bis Recommendation . 1 1 1 2 2 6 6 7 7 8 8 9 9 Recommendation 1.413 (03/93) i CCITT RECMNtI.413 (REV*cL) 93 m qBb2.591 0580795 853 m 1 B-TE1 Recommendation 1.413 1 B-NT2 B-NT1 B-ISDN USER-NETWORK INTERFACE (Geneva, 199
11、1; revised at Helsinki, 1993) 1 Introduction This Recommendation gives the reference configuration for the B-ISDN user-network interface (UNI) and examples of physical realizations. It desaibes physical layer information flows according to the B-ISDN Protocol reference model and identifies interface
12、 functions. It also addresses OAM issues as they relate to the reference configuration at the user access and to the interface specifications. 2 Reference configuration at the user-network interface 2.1 The reference configurations defined in Figure 1h.411 for ISDN basic access and primary access ar
13、e considered general enough to be applicable to all aspects of the B-ISDN accesses. Figure 1 shows the B-ISDN reference configurations which contain the following: functional groups: B-NT1, B-NT2, B-TE1, TE2, B-TE2 and B-TA; reference points: TB, SB and R. Functional groups and reference points - -
14、TI 81 1380-90/d01 Reference point I 0 Functional group B-TA Terminal adaptor for B-ISDN B-TE Terminai equipment for B-ISDN B-NT Network termination for B-ISDN FIGURE 1h.413 B-ISDN reference configurations Recommendation 1.413 (03/93) 1 In order to clearly illustrate the broadband aspects, the notati
15、ons for reference points and for functional groups with broadband capabilities are appended with the letter B (e.g. B-NT1, TB). The broadband functional groups are equivalent to the functional groups defined in Recommendation 1.411. Interfaces at the R reference point may or may not bave broadband c
16、apabilities. Interfaces at reference points SB and TB will be standardized. These interfaces will support all ISDN services. 2.2 Examples of physical realizations Figure 2 gives examples of physical configurations illustrating combinations of physical interfaces at various reference points. The exam
17、ples cover configurations that could be supported by standardized interfaces at reference points SB and TB. Other configurations may also exist. For example, physical configurations of B-NT2 may be distributed or use shared medium to support locai area network (LAN) emulation and other applications.
18、 Figure 3 illustrates possible physical configurations, but does not preclude alternative configurations. Whether a single interface at the SB reference point can cover different configurations as illustrated on Figure 3 is for further study. Figures 2a) and 2b) show separate interfaces at the SB an
19、d TB reference points; Figures 2c) and 2d) show an interface at SB but not at TB; Figures 2e) and 20 show an interface at TB but not at SB; Figures 2g) and 2h) show separate interfaces at S, SB and TB; Figures 2i) and 2j) show interfaces at SB and TB which are coincident. Additionally, Figures 2b),
20、2d), 20,2h) and 2j) show an interface at reference point R. 2.3 Basic characteristics of the interfaces at TB and SB reference points 2.3.1 Characteristics of the interfaces at 155.520 Mbih 2.3.1.1 Interface at TB reference point There are two options for the interface at the physical layer: a cell-
21、based physical layer and an SDH-based physical layer. The ATM layer is common to these two options. There is only one interface per B-NTl at the TB reference point. The operation of the physical medium is point-to-point in the sense that there is one sink (receiver) in front of one source (transmitt
22、er). When point-to-multipoint configurations at TB are used as an option at ATM and higher layers, their implications at these layers and the physical layer have to be studied. 2.3.1.2 Interface at the SB reference point There are two options for the interface at the physical layer: a cell-based phy
23、sical layer and an SDH-based physical layer. The ATM layer is common to both options. One or more SB interfaces per B-NT2 are present. The interface at the SB reference point is point to point at the physical layer in the sense that there is only one sink (receiver) in front of one source (transmitt
24、er) and may be point to multipoint at the other layers. 2.3.1.3 Relationship between interfaces at SB and TB Configurations described in Figures 2i) and 2j) require that the interface specifications at TB and SB have a high degree of commonality, in order to ensure that a simple broadband terminal m
25、ay be connected directly to the TB interface. The feasibility of achieving the needed commonality requires further study. 2 Recommendation 1.413 (03D3) CCITT RECMN*I.413 (REV*L) 93 S 4862591 0580797 626 TE2 or B-TE2 6-NT2 B-TE1 II 6-NT2 I_ I ,I B-TE1 Configurations where 6-ISDN physicd interfaces oc
26、cur at reference points + and TB B-NT2 + 8-NT1 II 1-1 8, s TE1 II II B-TE1 B-TE + B-NT2 B-TA + B-NT2 TE2 or B-TE2 Configurations where B-ISDN physical interfaces occur at reference point TB only It . B-NT1 1-1 II B-NT2 TE I, I_ 0 TA TE2 II 1-1 - II B-TE1 II 1-1 . B-NT1 II B-NT2 TE Equipment implemen
27、ting functiwial groups It , , (.t reference point Physical interface at the designated B-TE1 FIGURE 2A.413 Examples of physical configurations for broadband user applications II B-NT1 Recommendation 1.413 (03193) 3 II TE2 or I- I B-TE2 II II B-TA CCITT RECMN*I*433 (REV*L) 93 m 4862593 0580798 5b2 m
28、A B-TE t ENT2 B-TE t B-TE a) Centrallzed ENT2 configuration B-TE1 B-TE1 B-NT1 B-TE1 t B-NT1 b) Dlstrlbuted B-NT2 conguratlons bl) Generlc conguratlon (Note2) B-NT2 I I ,_- #, I MA B-NT1 (Note 1)l _-_- SB +i- SEqk B-TA B-TA B-TE1 R R B-TE2 B-TE2 b2) Physlcal conguratlons B-NT1 B-TE1 ENT1 ;i; B-TE1 c)
29、 Multlaccess - transmission interface handling; - OAM functions. Additional functions specific to the transmission system may be required. The means of powering of implementations of the B-NT1 is for further study. When the B-NT1 terminates cell-based OAM flows, cell delineation is required. 2.5.3 N
30、etwork termination 2 (B-NT2) for B-ISDN This functional group includes functions broadly equivalent to layer 1 and higher layers of the Recommendation X.200 reference model. B-NT2 can be null in the case of commonality between TB and SB. Examples of B-NT2 functions are: - - - cell delineation; - con
31、centration; - buffering; - multiplexing/demultiplexing; - resource allocation; - usage parameter control; - - - OAM functions; adaptation functions for different media and topologies (MA functions); functions of a distributed B-“2; adaptation layer functions for signalling (for internal traffic); in
32、terface handling (for the TB and SB interfaces); - signalling protocol handling; - switching of internal connections. B-NT2 implementations may be concentrated or distributed. in a specific access arrangement, the B-NT2 may consist only of physical connections. When present, implementations of the B
33、-NT2 are locally powered. 6 Recommendation 1.413 (03/93) CCITT RECMN*I.413 (REVJL) 93 m 4862591 058080L 987 m 2.5.4 Terminal equipment (B-TE) for B-ISDN This functional group includes functions broadly belonging to iayer 1 and higher layers of the Recommendation X.200 reference model. Examples of B-
34、TE functions are: - user/user-and-user/machine dialogue and protocol; - - protocol handling for signalling; - - OAM functions. interface termination and other layer 1 functions; connection handling to other equipments; The possibility of powering the B-TE via the SB interface is for further study. 2
35、.5.4.1 Terminal equipment type 1 (B-TE1) for B-ISDN This functional group includes functions belonging to the B-TE functional group with an interface that complies with the B-ISDN SB andor TB interface Recommendations. 2.5.4.2 This functional group includes functions belonging to the functional grou
36、p B-TE but with a broadband interface that complies with interface Recommendations other than the B-ISDN interface Recommendations or interfaces not included in CCITT Recommendations. Terminal equipment type 2 (B-TE2) for B-ISDN 2.5.5 This functional group includes functions broadly belonging to lay
37、er 1 and higher layers of the Recommendation X.200 reference model that ailow a TE2 or a B-TE2 terminal to be served by a B-ISDN user-network interface. Terminal adaptor (B-TA) for B-ISDN 3 Physica layer information flows and interface functions Physical layer functions and physical iayer primitives
38、 are defined in Recommendation 4.2h.321. The present clause defines the information flows between the physical medium (PM), the transmission convergence sublayer (TC) and their adjacent entities (ATM layer and management plane). The information flows identified here do not imply any physical realiza
39、tion. Information flows identified in this clause may not be exhaustive. 3.1 Relation with other sublayers or entities The information flows specified in the following subclauses will be provided in Recommendation 1.321 by primitives. Further study is required to specify these primitives. 3.1.1 Info
40、rmation exchanged between the PM and the TC sublayers a) From the PM sublayer to the TC sublayer: The PM sublayer provides at least the following information to the TC sublayer: - - associated timing information. From the TC sublayer to the PM sublayer: The TC sublayer provides at least the followin
41、g information to the PM sublayer: - - associated timing information. a flow of logical symbols (e.g. bits), b) a flow of logical symbols (e.g. bits), Recommendation 1.413 (03/93) 7 CCITT RECMN*I.413 (REV831 73 I 4862573 0580802 813 I 3.1.2 Information exchanged between the physical layer and the ATM
42、 layer a) From the physical layer to the AW layer I): The physical layer provides at least the following information to the ATM layer: - - From the A7M layer to the physical layer: - - valid cells (excluding idle cells and physical layer OAM cells), associated timing (e.g. presence of data and clock
43、 information). assigned and unassigned cells if any available, associated timing (e.g. presence of data and clock information). In case no cells are available, no data are transferred and the physical layer inserts idle cells to build up the data flow to be transmitted. b) 3.1.3 Information exchange
44、d between the physical layer and the management plane a) From the physical layer to the management plane: - loss of incoming signal; - indication of received errors or indication of degraded error performance. Detection of bit errors may be based on received unexpected code violations or other bit e
45、rror detecting schemes. In addition, other information may be provided to the management plane. This is for fwther study. From the management plane to the physical layer: For further study. b) 3.2 Modes of operation Nod mode: ?fully active?. Other modes, e.g. emergency mode in case of power failure
46、or deactivated mode in order to save power are for further study. 3.3 Interface function 3.3.1 Data transfer The user information together with the information for connection related functions (e.g. signalling) are carried in ATM cells. OAM information related to the physical layer is carried in tra
47、nsmission overheads or PL-OAM cells, depending on the transmission sructure used (SDH-based or cell-based) and on the functional entity concerned. 3.3.2 TMng Bit timing has to be provided according to Recommendation 1.432. 3.3.3 Bit sequence independence The PM and the associated transmission system
48、 payload have to provide bit sequence independence. i) The physical layer will provide a clock to the ATM layer. This clock is derived om the line rate of the physical layer (e.g. a bit clock at 155.52 Mbit/s for the user-network interface standardized in Recommendation 1,432). For certain applicati
49、ons, there may be a need to indicate to the ATM layer that an idle cell has been discarded by the physical layer. Two possible applications are generic flow control (GFC) and the shaping of traffk flows. 8 Recommendation 1.413 (03/93) CCITT RECMN*I.413 (REV81) 73 S 48b2571 0580803 75T 3.3.4 Provision of power feeding For further study. 3.3.5 Activationldeactivation For further study. 4 UNI related OAM functions The following OAM functions associated with the UNI have been identified and are described in Recommenda- tion 1.6 10: 1) transmission and reception of ma
