1、 AMERICAN NATIONAL STANDARD FOR TELECOMMUNICATIONS ATIS-0300216.2013 INTEGRATED SERVICES DIGITAL NETWORK (ISDN) MANAGEMENT BASIC RATE PHYSICAL LAYER As a leading technology and solutions development organization, ATIS brings together the top global ICT companies to advance the industrys most-pressin
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11、physical termination at the customer end is the Network Termination (NT). 3.1.8 digital test access unit (DTAU): A generic term for the functions associated with accessing one or more channels within a digital signal for the purpose of testing. DTAU functionality may be embedded within a Network Ele
12、ment (NE) or may consist of stand-alone equipment. 3.1.9 integrated digital loop carrier (IDLC): Digital Loop Carrier (DLC) for which the multiplexing function near the Exchange Termination (ET) is integrated into the ET. _ 2This document is available from the International Telecommunications Union.
13、 ATIS-0300216.2013 3 Figure 1 - ISDN Basic Access reference configuration NOTE: In most cases, the NI is located on the network side of the NTI. In certain cases, the NI may be located at a point that is functionally equivalent to the T-Reference point. 3.1.10 intermediate element (IE): A generic te
14、rm used to denote either a Line Unit Line Termination (LULT) or a Line Unit Network Termination (LUNT). 3.1.11 line unit line termination (LULT): The network side of any Digital Subscriber Line (DSL) that does not terminate on the Exchange Termination (ET). 3.1.12 line unit network termination (LUNT
15、): The customer side of any Digital Subscriber Line (DSL) that does not terminate on the Customer Installation (CI). 3.1.13 loopback point: The location of the loopback. 3.1.14 metallic test access unit (MTAU): A generic term for the functions associated with accessing a metallic facility for the pu
16、rpose of testing. MTAU functionality may be embedded within a Network Element (NE) or may consist of stand-alone equipment. 3.1.15 network element (NE): Telecommunication equipment (groups or parts) within ISDN that pro-vides support and/or service to the customer. 3.1.16 network interface (NI): The
17、 point of demarcation between the network and the Customer In-stallation (CI) (see Figure 1). 3.1.17 non-transparent loopback: A loopback in which the signal transmitted beyond the loopback point (the forward signal) when the loopback is activated, is not the same as the received signal at the loopb
18、ack point (see Figure 2). The forward signal may be a defined signal or unspecified. 3.1.18 operations system (OS): A system that processes information related to telecommunication management to support and/or control the realization of various telecommunication management func-tions. To support Cus
19、tomer Access (CA) maintenance, OSs must perform surveillance and testing func-tions. 3.1.19 remote digital terminal (RDT): The Digital Loop Carrier (DLC) multiplexer that is at the end of the DLC that is closest to the Network Interface (NI). 3.1.20 test system controller/remote test unit (TSC/RTU):
20、 A generic term for the testing functions that are performed on the Customer Access (CA). TSC/RTU functionality may be embedded within a Network Element (NE) or may consist of stand-alone equipment. ATIS-0300216.2013 4 Figure 2 - Loopback types NOTE: Transparent and Non-transparent loopback should n
21、ot be affected by facilities connected beyond the point at which the loop is provided e.g., by the presence of short circuits, open circuits, or foreign voltages. 3.1.21 transparent loopback: A loopback in which the signal transmitted beyond the loopback point (the forward signal) when the loopback
22、is activated, is the same as the received signal at the loopback point (see Figure 2). 3.1.22 universal digital loop carrier (UDLC): Digital Loop Carrier (DLC) that uses a Central Office Terminal (COT). 3.2 Acronyms AMC Administration Management Center ANSI American National Standards Institute BRA
23、Basic Rate Access BRI Basic Rate Interface CA Customer Access CCITT International Telegraph and Telephone Consultative Committee (now called ITU-T) CI Customer Installation CMC Customer Management Center COT Central Office Terminal CRC Cyclic Redundancy Check CV Coding Violation DLC Digital Loop Car
24、rier DOI Disruptive Operations Indication (DOI) DSL Digital Subscriber Line DTAU Digital Test Access Unit DTSE Detected Access Transmission System Error ATIS-0300216.2013 5 EOC Embedded Operations Channel ES Errored Second ET Exchange Termination FEBE Far End Block Error FECV Far End Code Violation
25、IDLC Integrated Digital Loop Carrier IE Intermediate Element ISDN Integrated Services Digital Network ITU-T International Telecommunications Union Telecommunications Standardization Sector LB1I Loopback B 1 Indication LB1/2I Loopback B 1 Maintenance of the Customer Access (4.2); The Customer Install
26、ation (4.3); Maintenance of the Customer Installation (4.4). 4.1 Customer Access A variety of configurations can be used for BRA transport. The ISDN user may be served from the local central office (i.e., interoffice facilities are not used), or from a remote central office (i.e., interoffice facili
27、ties are used). In transporting the access line, it is possible to utilize Digital Subscriber Lines (DSLs), Digital Loop Carrier (DLC) (used to access the local central office), D channel banks (used to access the remote central office via interoffice facilities), or a combination of these. Figure 3
28、 shows typical configurations that represent the ISDN maintenance models for BRA transport. Each configuration (including the network view as provided via performance monitoring) is further discussed below. Figure 3 - ISDN models for Basic Rate Customer Access ATIS-0300216.2013 7 Figure 3(a) shows l
29、ocal access using a simple DSL. Performance monitoring occurs on the DSL between the LT and NT. Figures 3(b) through 3(e) show BRA configurations having one or more transmission links or segments in tandem. For BRAs made up of several segments, performance monitoring at layer 1 can, at the providers
30、 option, be accomplished using either a “segmented monitoring” or a “path monitoring” approach (as de-scribed in 5.2.1). Figure 3(b) shows local access using Integrated Digital Loop Carrier (IDLC). Note that the IDLC portion of the access line need not have dedicated time slots for the B or D channe
31、ls. When dedicated time slots are assigned, either path or segment monitoring may be provided for the 2B+D path between the ET and the NT. When the timeslots are not dedicated, only the DSL between the LULT and NT is monitored and thresholded. To provide an overall view of the BRA, this information
32、must be combined with performance information for the DS1 facility between the ET and Remote Digital Terminal (RDT). This can be done by an OS within the Administration Management Complex (AMC). Figure 3(c) shows local access using Universal Digital Loop Carrier (UDLC). Note that the UDLC portion of
33、 the access line need not have dedicated time slots for the B or D channels. When dedicated time slots are assigned, either path or segment monitoring may be provided for the 2B+D path between the ET and the NT. When the timeslots are not dedicated, the DSL between the LULT and NT and the DSL betwee
34、n the LT and LUNT are monitored and thresholded independently. To provide an overall view of the BRA, this information must be combined with performance information for the DS1 facility between the Central Office Terminal (COT) and RDT. This can be done by an OS within the AMC. Figure 3(d) shows rem
35、ote access using D-banks. Note that the DS1 portion of the access line need not have dedicated time slots for the B or D channels. When dedicated time slots are assigned, either path or segment monitoring may be provided for the 2B+D path between the ET and the NT. When the timeslots are not dedicat
36、ed, the DSL between the LULT and NT and the DSL between the LT and LUNT are moni-tored and thresholded independently. To provide an overall view of the BRA, this information must be combined with performance information for the DS1 facility between the D-banks. This can be done by an OS within the A
37、MC. Figure 3(e) shows remote access using UDLC and D-banks. Note that neither the UDLC portion nor the D-bank portion of the access need have dedicated time slots for the B or D channels. When dedicated time slots are assigned, either path or segment monitoring may be provided for the 2B+D path betw
38、een the ET and the NT. When the timeslots are not dedicated, performance monitoring occurs on the DSL between the LULT in the RDT and NT, the DSL between the LULT in the D-bank and the LUNT in the COT, and the DSL between the LT and the LUNT in the D-bank. To provide an overall view of the BRA, this
39、 information must be combined with performance information for the two DS1 sections of the access. This can be done by an OS within the AMC. 4.2 Maintenance of Customer Access Figure 4 shows a model for the maintenance of the Customer Access (CA). Maintenance of the CA may use the following function
40、al interfaces: Surveillance OS Network Element (NE); Surveillance OS TSC/RTU (for surveillance of the TSC/RTU); Testing OS TSC/RTU (and/or NE); and TSC/RTU NE. ATIS-0300216.2013 8 The TSC/RTU-to-NE relationship consists of a control link and a test access link. The control link is used by the TSC/RT
41、U to control test access functions in the NE and may be provided via a data communications network. Tests are performed via the test access link. 4.3 Customer Installation The wide variety of user application equipment attaching to a Basic Rate Interface (BRI) will require a range of maintenance fun
42、ctions. Equipment may range from devices with no maintenance capabilities to devices with multiple maintenance capabilities. For this reason, the maintenance requirements at the S and T reference points are optional. Examples of user equipment realizations for basic access are shown in Figure 5. Fig
43、ure 5(a) shows a simple point-to-point connection between the NT1 and a single TE1. Figure 5(b) shows a passive bus between the NT1 and a TE1 and a Terminal Adaptor (TA). Figure 5(c) shows a star configuration with a TE1 and a TA connected to the NT1 via separate cabling. Figure 5(d) shows a simple
44、customer installation that combines the NT1 and TE1 functionality into one piece of equipment. Figure 5(e) shows a customer installation where the NT1 and NT2 functionality are combined into one piece of equipment. Figure 5(f) shows an NT2 connected to multiple NT1s and multiple TE1s. In Figures 5(e
45、) and 5(f), the NT2 and the NT1+NT2 may provide switching among TE1s. Maintenance at the U and S/T reference points is covered by this standard. Maintenance at the R reference point shown in Figures 5(b) and 5(c), between the TE2 (non-ISDN entity) and the TA is beyond the scope of this standard. In
46、most cases, the NI is located on the network side of the NT1. In certain cases, the NI may be located at a point that is functionally equivalent to a T-Reference Point. 4.4 Maintenance of the Customer Installation The maintenance of the Customer Installation (CI) is to allow the isolation and testin
47、g of customer-specific components and interfaces up to the Network Interface (NI). Two approaches used for maintenance of the CI are continuous monitoring and event-driven maintenance procedures. These procedures make use of physical layer overhead channels as specified in ATIS-0600605. The channels
48、 are referred to as S in the direction from the NT to the TE, and Q in the direction from the TE to the NT. Continuous monitoring includes the decoding by the customer equipment of monitoring information passed across the NI by the NT1. This monitoring information includes performance indicators and
49、 status indi-cators of the S/T and U Reference Point operation, and of the NT1 component, where present. The structure and organization of the S channels follows the organization shown in Figure 6. SC1 and SC2 are functionally independent maintenance sub-channels. SC1 is used to convey real-time information about status, performance, and maintenance functions (see Table 3). SC23is used to convey the U Reference Point operation mapping information (see Table 4). The maintenance uses of SC3, SC4, and SC5 are for further study. Event-driven maintenance pr
