Question 8/XVII - Measuring criteria for telephone-type circuits appropriate to their use for transmission of data signals (Continuation of Question 8/XVII, 1985-1988); (Concerns Study Groups IV, XII and XV-Q.26/XV) Considering that the transmission characteristics of leased telephone- type circuits are described in the following Recommendations: (a) ordinary telephone-type circuits (M.1040/H.12.A); (b) special quality leased circuits with basic bandwidth conditioning (M.1025/H.12.B); (c) special quality leased circuits with special bandwidth conditioning (M.1020/H.12.C), 1. the following line parameters and the measuring techniques to measure these parameters, arising from these Recommendations, should be studied from a data transmission point of view: a) Bandwidth characteristics: i) Ordinary telephone-type circuits: - overall loss frequency distortion. ii) Special quality leased circuits with basic bandwidth conditioning: -overall loss frequency distortion, -group delay distortion. b) Interface characteristics: i) Ordinary telephone-type circuits: -nominal overall loss. ii) Both types of special quality leased circuits: -nominal overall loss. c) Transmission system characteristics: i) Ordinary telephone-type circuits: -random circuit noise. ii) Both types of special quality leased circuits: -random circuit noise (Note 2), -impulsive noise, -phase jitter, -single tone interference, -quantizing noise (Note 2), -harmonic distortion (intermodulation distortion) (Note 2). d) Additionally the study should include the following transmission system characteristics of both types of special quality leased circuits: -short breaks in transmission (drop-outs), -phase hits, -amplitude hits, -low frequency phase jitter. e) Points of study for telephone-type circuits: -The study of the appropriate measuring criteria for the impairments to data signals caused by the introduction of ADPCMs, A/D converters and a/u law converters to the telephone network. 2. In addition, the following issues also require further study: a) Are there any special requirements for the operation of two- wire, duplex modems operating at data signalling rates above 1200 bit/s? b) What is the effect on data transmission between V-Series modems if, by some chance, all of the transmission characteristics of circuits leased for data transmission are at their lower limit (as specified in Recommendation H.12.A, B or C/M.1040, 1025 or 1020 respectively)? c) How might a "Figure of Merit" or some measuring technique be defined to insure the operation of V-Series modems to the performance specified in Recommendation V.53? d) How should the bandwidth and transmission system parameters (such as random circuit noise) be allocated in the case of simple multipoint circuits? e) What guidance should be given to the Study Groups deliberating the appropriate number of quantizing distortion units to be assigned to 32 kbit/s ADPCMs to ensure that adequate consideration is given to the satisfactory performance of V-Series modems? Note 1 - Study Group XVII's attention is called to the following questions from Joint Study Group CMBD which arose from the statement of Study Group XVII that transmission interruption longer than 5-15 ms could result in a service interruption of a duration of up to 1 second: a) Do these transmission interruptions cause disconnection of the established connection? b) If not, what frequency of such interruptions is acceptable for data transmission? Note 2 - In order to enhance the probability of the satisfactory operation of certain V-Series modems at data signalling rates higher than 4800 bit/s, the following are some of the transmission system characteristics that require further study: -random circuit noise (possibly given as a signal/noise ratio); -quantizing noise (possibly using a single frequency tone source); -harmonic distortion (possibly measured as second and third order intermodulation distortion products). Question 9/XVII - Network Management Continuation of Question 9/XVII, 1985-1988; revised title and wording) (Concerns Study Group VII) Considering (a) that the management/maintenance of data networks can be accomplished by administrations, RPOAs, and users, and that management/maintenance principles must be harmonized to: i) offer optimum network management and testing facilities to the administrations, RPOAs and users; ii) define consistent network management and testing facilities, (b) that ISO/IEC JTC 1/SC 21, SC 6 and CCITT are developing standards for OSI management for interconnection of different systems and networks with diverse architectures; (c) that there exists a large installed base of V-Series DCEs with network management capability implemented with diverse architectures; (d) that it is desirable to provide system management to devices in multiple-protocol, non-homogeneous networks; (e) that Recommendation V.230 specifies the electrical character- istics for a new physical interface for V-Series DCEs that will offer a migration path to the ISDN; (f) that Recommendation V.54 defines loop test devices for modems; (g) that Recommendation V.25bis defines a serial automatic calling and answering procedure on the GSTN supported by the DTE/DCE V.24 interface, the following should be studied: an OSI network management protocol for use between a V-Series DCE and a network management system as well as the means to communicate this information between the two. This should be provided in such a way as to assure a nondisruptive separation of the management information and the user data. A methodology must therefore be specified that would provide management information with a communications path between the management system and the managed DCE. In particular, the following points should be considered: 1. What principles are required for the network management and testing facilities to be consistent with the overall CCITT ISO-IEC activities on network management? 2. What general functional requirements for management must be defined? 3. How do the OSI management applications apply to V-Series DCEs and what additional network management aspects should be studied? 4. How can V.230 be used to provide a network management information path? 5. How can existing V-Series DCEs with diverse management architectures be accommodated? 6. How can multiple separate DCEs be managed from a system manager in non- homogeneous networks independently of diverse user protocols? 7. How can the work be harmonized with points of study under Questions 14/XVII and 23/XVII?