1、 AMERICAN NATIONAL STANDARD FOR TELECOMMUNICATIONS ATIS-1000646.2003(R2015) Network and Customer Installation Interfaces Broadband ISDN: Common Criteria As a leading technology and solutions development organization, ATIS brings together the top global ICT companies to advance the industrys most-pre
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11、and Reference points UB, TB, SB, SSB, and RB.4Functional groups are sets of functions needed in B-ISDN customer access arrangements. In a particular access arrangement, specific functions in a functional group may or may not be present. Specific functions in a functional group may be performed in on
12、e or more pieces of equipment. Reference points are conceptual points dividing functional groups. To clearly illustrate the broadband aspects, the notations for reference points (U, T, and S) and for functional groupings with broadband capabilities are augmented with the letter B (e.g., B-NT1, TB).
13、The SSB reference point is not borrowed from narrowband or primary rate ISDN, and hence is denoted as SSB only. Interface points at reference points UB, TB, SB, and SSB are standardized.5These interface points support all ISDN services. 3Note that this use of the acronym NE differs from its use in o
14、ther T1 standards to refer to as “Network Element.“ 4The reference point RBis included here to indicate how non-B-ISDN terminals can be utilized. This situation is discussed in 4.2.3.2 and 4.2.4. 5ITU-T Recommendation I.432.1 also specifies physical layer interface characteristics for T and S refere
15、nce points. ATIS-1000646.2003 4 Figure 2 gives examples of physical configurations illustrating combinations of physical interfaces associated with various reference points. The examples cover configurations that could be supported by standardized interfaces at UB, TB, and SB. Other configurations m
16、ay also exist. For example, physical configurations of B-NTs (Broadband Network Terminations) may be distributed or use shared medium to support Local Area Network (LAN) emulation and other applications. Figure 3 illustrates possible physical configurations, but does not preclude alternatives. Multi
17、ple Broadband Medium Adapters (B-MAs) could form a B-NT2 functional grouping connected in conformance with the star topology of ANSI/EIA/TIA 568 (see Figure 4). This topology, which allows ready cross-connect access of connecting cables for the ease of maintenance and administration at designated di
18、stribution points in a building, is also applicable to connections between a B-MA and multiple pieces of Broadband Terminal Equipment (B-TE). 4.1.1 TBreference point There is only one point-to-point interconnection near the B-NT1 associated with the TBreference point. More than one physical layer in
19、terface point may exist within each interconnection (see 4.3). The physical media is point-to-point, in the sense that there is only one receiver connected to one transmitter. 4.1.2 UBreference point There is only one point-to-point interconnection near the B-NT1 associated with the UBreference poin
20、t. More than one physical layer interface point may exist within each interconnection (see 4.3). The physical media is point-to-point, in the sense that there is only one receiver connected to one transmitter. 4.1.3 SBreference point One or more point-to-point interconnections per NT2 are present at
21、 SBreference points. More than one physical layer interface point may exist within each interconnection (see 4.3). The connection at the SBreference point is point-to-point at the physical layer, in the sense that there is only one receiver in front of one transmitter and may be point-to-multipoint
22、at the higher layers. 4.1.4 SSB reference point The point-to-point interconnection at the SSB reference point exists between two B-TEs and the physical layer specification is identical to that at the SBreference point, including PMD and transmission convergence specifications. 4.1.5 Commonality betw
23、een SBand TBConfigurations described in Figures 2i and 2j require that the interface point specifications associated TBand SBshould have a high degree of commonality, to ensure that a simple broadband terminal may be connected directly to the interface point associated with the TBreference point. 4.
24、2 Functional group characteristics Lists of functions for each functional group are given below. Each particular function is not necessarily restricted to a single functional group. For example, “interface termination” functions are included in the function lists of B-NT1, B-NT2, ATIS-1000646.2003 5
25、 and B-TE. The function lists for B-NT1, B-NT2, B-TE, and B-TA are not exhaustive. Not all specific functions in a functional group are required in all implementations. 4.2.1 Network termination 1 (B-NT1) for B-ISDN This functional group includes functions broadly equivalent to layer 1 of the ITU-T
26、Recommendation X.200 reference model. Examples of B-NT1 functions are: Line transmission termination; Interface handling at UBand TB; and Operations and maintenance (OAM) functions. 4.2.2 Network termination 2 (B-NT2) for B-ISDN This functional group includes functions broadly equivalent to layer 1
27、and higher layers of the ITU-T Recommendation X.200 reference model. The B-NT2 functional group may be concentrated or distributed. In a specific access arrangement, the B-NT2 functional group may consist of physical connections. Examples of B-NT2 functions are: Adaptation functions for different me
28、dia and topologies (B-MA); Functions of a distributed B-NT2; Cell delineation; Concentration; Buffering; Multiplexer/demultiplexer; Resource allocation; Usage parameter control; ATM adaptation layer (AAL) functions for signaling (for internal traffic); Interface handling (for interface points associ
29、ated with the TBand SBreference points); OAM functions; Signaling protocol handling; and Switching of internal connections. When present, implementations of the B-NT2 are locally powered. B-NT2 can be null in the case of coincidences between TBand SB. 4.2.3 Terminal equipment (B-TE) for B-ISDN This
30、functional group includes functions broadly belonging to layer 1 and higher layers of the ITU-T Recommendation X.200 reference model. Examples of B-TE functions are: User-user and user-machine dialogue and protocol; Interface termination and other layer 1 functions; ATIS-1000646.2003 6 Protocol hand
31、ling for signaling; Connection handling to other equipment; and OAM functions. 4.2.3.1 Terminal equipment type 1 (B-TE1) for B-ISDN This functional group includes functions belonging to the functional group B-TE having an interface that complies with the B-ISDN interface as described in this documen
32、t. 4.2.3.2 Terminal equipment type 2 (B-TE2) for B-ISDN This functional group includes functions belonging to the functional group B-TE but with a broadband interface that complies with: Interfaces not included in ITU-T (formerly CCITT) recommendations; and Interface recommendations other than the B
33、-ISDN interface recommendations. Therefore, the corresponding reference point RBcharacteristics are not specified in this standard. 4.2.4 Terminal adapter (B-TA) for B-ISDN This functional group includes functions broadly belonging to layer 1 and higher of the ITU-T Recommendation X.200 reference mo
34、del that allow a B-TE2 terminal to be served by a B-ISDN UNI. The corresponding reference point in such a configuration is called RB(see 4.2.3.2 and Figure 1). 4.3 Interface points Iaand IbInterface points are physical locations designating the boundary of functional groupings. Interface point Iais
35、adjacent to the B-TE, B-NT2, and B-NT1 on their network side; interface point Ibis adjacent to the B-NT2 and B-NT1 on their user side (refer to Figures 5 and 6 for a graphical representation). For optical specifications, the interface points are located between the socket and the plug of the connect
36、or attached to the B-TE, B-NT2, or B-NT1. The optical parameters for such connections are specified in T1.416.04-2005. For electrical specifications, the interface points are located as described in T1.403.03-2002 (DS1), T1.404.01-2000 (DS3), and T1.416.04-2005 (SONET). 5 Maintenance This clause dea
37、ls with physical layer maintenance functionality. Physical layer maintenance is accomplished by monitoring the received signals, as shown in Figure 7. Figure 7 illustrates, in a generic way, the separation of the physical and ATM layers, and also the way monitored parameters are used both by the lay
38、er management entity and for failure and performance monitoring. Near-end ATIS-1000646.2003 7 (NE) events - in terms of anomalies and defects - and far-end (FE) reports - in terms of anomalies, defects and failures - are specific to the type of facility and are discussed below. NE events and FE repo
39、rts shall be used for three purposes: All NE events and FE reports shall be processed for performance monitoring parameters and failures as per T1.231-1997. NE events and (processed) failures shall be used to make up FE reports for the transmitted signal. NE and FE defects at the facility path and c
40、ell delineation level shall be sent to the layer management entity to inform it of transport problems. Figure 1 - B-ISDN Reference Configuration ATIS-1000646.2003 8 Figure 2 - Examples of physical configurations for B-ISDN user applications ATIS-1000646.2003 9 Figure 3 - Example of physical configur
41、ation for shared medium applications ATIS-1000646.2003 10 Figure 3 - (concluded) ATIS-1000646.2003 11 Figure 4 - Example of star implementation Figure 5 - Physical interface point Iaassociated with UBATIS-1000646.2003 12 Figure 6 - Physical interface points Iaand Ibassociated with TBFigure 7 - Physi
42、cal layer maintenance functions ATIS-1000646.2003 13 Figure 8 - Fault conditions associated with UNIs ATIS-1000646.2003 14 Annex A (informative) A Bibliography The following documents are for information only and are not essential for completion of the requirements of this standard. T1.624-1993, Bro
43、adband ISDN User-Network Interfaces - Rates and formats specifications (superseded by T1.646-1995)6,1T1.627-1993 (R1999), Broadband ISDN ATM layer functionality and specification.1TIA/EIA-568 SET, Commercial Building Telecommunications Cabling Standards Set Part 1: General Requirements Part 2: Balan
44、ced Twisted-Pair Cabling Components Part 3: Optical Fiber Cabling Components Standard.7ITU-T Recommendation I.113, Vocabulary of terms for broadband aspects of ISDN, 1997.2ITU-T Recommendation I.121, Broadband aspects of ISDN, 1991.2ITU-T Recommendation I.150, B-ISDN ATM functional characteristics,
45、1999.2ITU-T Recommendation I.321, B-ISDN protocol reference model and its application, 1991.2ITU-T Recommendation I.327, B-ISDN functional architecture, 1993.2ITU-T Recommendation I.411, ISDN user network interfaces Reference configurations, 1993.2ITU-T Recommendation I.413, B-ISDN user-network inte
46、rface, 1993.2ITU-T Recommendation X.200, Information Technology - Open Systems Interconnection - Basic Reference Model: The basic model, 1994.2ITU-T Recommendation G.804, ATM cell mapping into plesiochronous digital hierarchy (PDH), 1998.26Reference to superseded T1.624-1993 is included here only to provide insight into the history of this standard; it is not available. 7Available from Global Engineering Documents, 15 Inverness Way East, Englewood, CO 80112
