1、 ATIS-1000620.a.2014 Multi-Rate Circuit-Mode Bearer Service for ISDN Addendum to the Circuit-Mode Bearer Service Category DescriptionAMERICAN NATIONAL STANDARD FOR TELECOMMUNICATIONS As a leading technology and solutions development organization, ATIS brings together the top global ICT companies to
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11、stitute. Notice of Disclaimer -for the basic-rate interface at the U reference point (see ATIS-0600601). each layer 1 frame constitutes twelve whole 125 sec intervals; -for the primary-rate interface (see ATIS-0600408), each layer 1 frame constitutes one whole 125 sec interval. (This note is not in
12、ITU-T Recommendation 1.140). 3.13 Time slot sequence Integrity: (see ITU-T Recommendation 1.140, annex A.) This value applies when: 4 ATIS-1000620.a.2014 a) At each user-network interface, time slots are implicitly or explicitly demarcated for each access channel of an aggregate of access channels;
13、and b) The information parts delivered from the time slots at the receiving end are in the same order as submitted at the transmitting end. NOTE- Preserving the order of the bits within an individual time slot from the transmitting to the receiving end is not part of this definition. 3.14 unrestrict
14、ed digital Information: (see ITU-T Recommendation 1.140, annex A.) Transfer of information sequence of bits at its specified rate without alteration .This implies: -bit sequence independence; -digit sequence integrity; bit integrity. 3.15 contiguous time-slot assignment: The time slots used for the
15、call are adjacent. 3.16 noncontiguous time-slot assignment: The time slots used for the call are not necessarily adjacent. 1.4 Add the following list item to clause 4, “General description“: h) Circuit-Mode, multi-rate. 1.5 Add the following paragraph to 5.1, “Provision and withdrawal“: For the mult
16、i-rate bearer-service category, the service provider may support contiguous time-slot assignment or noncontiguous time slot assignment on the access interface .The set of information transfer rates supported by the service provider is a service-provider option. Table 1, Subscription options is atten
17、ded as follows: Table 1 - Subscription Options ATIS-1000620.a.2014 1.6 Add the following text as 5.3.4, “Failure situation during call“: 5.3.4 Failure situation during Call If the network or the user cannot continue to support the information transfer rate requested at call setup, then the entity th
18、at detects the failure shall initiate call termination procedures with an appropriate indication of the cause of failure . Add the following items to clause 7, “lnterworking requirements“: g) Between the ISDN and a non-ISDN network offering the multi-rate bearer service; h) Between the multi-rate be
19、arer service and the 384 kbit/s, 1472 kbit/s and 1536 kbit/s circuit- mode digital bearer services. 1.7 Add the following text as 4.8, “multi-rate circuit -mode 9earer service category“ : 4.8 Multi-rate circuit-mode bearer service category The multi-rate circuit-mode bearer service category allows u
20、sers to request from the ISDN on a demand basis the establishment and release of circuit-mode connections supporting unrestricted information transfer rates at integer multiples of 64 kbit/s from 128 kbit/s up to and including 1536 kbit/s for the primary-rate ISDN interface and 128 kbit/s for the ba
21、sic-rate ISON interface. This bearer service category supports rates of 128,192,.,1536 kbit/s corresponding to n x 64 kbit/s where n = 2,3,.,24 using multiple B-channels lor the primary-rate interface . For the basic-rate interface, this bearer-service category supports 128 kbit/s using two B-channe
22、ls. This bearer service category allows unrestricted transfer of n x 64 kbit/s user information (where n = 2- 24 for primary rate and n = 2 for basic rate) without alterations at the S, Tor U reference point. It is the users responsibility to provide for compatibility between the user equipment at e
23、ach S,Tor U reference point . The network transports the user data using 8-kHz integrity with time-slot sequence integrity . This ATIS-1000620.a.2014 bearer service category also preserves the order of the bits within an individual time slot from the transmitting to the receiving end. This bearer se
24、rvice category is applicable to the primary-rate ISDN interface and basic-rate ISDN interface and is suitable for various applications. Examples of applications include: a) Business video conferencing based on the use of video codec operating at multiples of 64- kbit/s rate as specified, for example
25、, in ITU-T Recommendation H.261; b) Interconnection of Local Area Networks (LANs); c) Interconnection of mainframes; d) Desktop video conferencing and imaging; e) Private network backup for disaster recovery. This bearer service category is transferred over multiple time slots; signalling is provide
26、d in the D-channel of the same interface structure for the basic-rate or primary-rate interface or in the D- channel of another interface in the case of the primary-rate interface. NOTE - Providing signaling on the same primary-rate interface limits the maximum transfer rate to 1472 kbitls (23 x 64
27、kbit/s); otherwise, it can reach 1536 kbit/s (24 x 64 kbit/s) This Circuit-Mode bearer service category allows: two users (e.g., workstations, multiplexers, host computers, PBXs) in a point-to-point configuration to communicate via the ISDN using n x 64 kbit/s digital signals (where n = 2 - 24 for p
28、rimary-rate interface and n = 2 for basic-rate interface) in both directions continuously and simultaneously for the duration of the call. The time-slot assignment has a local meaning only. In particular, the contiguous assignment of time slots at one interface does not mean that the time slots shal
29、l be assigned contiguously within the network and at the terminating interface. The time slots selected shall belong to a single interface and shall not span several interfaces. The information-transfer attributes and their values for this bearer service category are as follows: a) Information trans
30、fer mode: Circuit b) Information transfer rate: Multi-Rate (128, 192, ., 1536 kbit/s) . c) Information transfer capability : Unrestricted digital information d) Structure : 8 kHz Integrity with Time slot sequence integrity e) Establishment of communication : Demand f) Communication configuration: Point-to-point. g) Symmetry: Bidirectional symmetric. 1.8 Add the following item to annex A, “Differences between this standard and ITU-T Recommendation I231 “: 14. Clause 4.0 item (h) , and subclause 4 .8 : ITU-T Recommendation I.231 does not identify a category for multi-rate circuit mode.
