џWPCL ћџ2BJ|xа АH аа АА X агга ХА6p&А6p&Х аеI а HH аааб cмˆ4 PŽТ б У Уб cмˆ4 PŽТ бstyleref head_footRecommendation G.958б cмˆ4 PŽТ бФ Ф PAGE1 б cмˆ4 PŽТ бУ УееЌ† а HH аааб cмˆ4 PŽТ бPAGE22 У Уб cмˆ4 PŽТ бstyleref head_footRecommendation G.958 Ќеа HH ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи P Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаа X Ш аб cмˆ4 PŽТ бУ УRecommendation G.958 аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџH јP Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бФ ФRecommendation G.958 а Hр ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи P Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬа‚СрА2СУ Уб cмˆ4 PŽТ бDIGITAL LINE SYSTEMS BASED ON THE SYNCHRONOUS DIGITAL HIERARCHY СрАCСFOR USE ON OPTICAL FIBRE CABLES б cмˆ4 PŽТ б1ТX ТIntroductionФ ФЦЦ 1.1Тh  ТУУGeneralФФЦЦ С СThe CCITT, УУconsidering а H аФФС С(a)СpСthat Recommendations G.707, G.708 and G.709 specify the bit rates, the multiplexing structure and the detailed mappings associated with the synchronous digital hierarchy (SDH); С С(b)СpСthat Recommendations G.781, G.782, G.783 specify the general characteristics and functions of synchronous multiplexing equipment and Recommendation G.784 the management of SDH equipment and networks; а H аС С(c)СpСthat Recommendations G.703 and G.957 specify the physical parameters of the electrical and optical interfaces of SDH equipment; а H аС С(d)СpСthat Recommendations of Serie G.780 specify SDH multiplexing equipment in terms of functional blocks without any constraint on physical implementation; С С(e)СpСthat among the first generation of SDH equipment there will be synchronous line systems; С С(f)СpСthat there is a need to ensure that these new systems provide longitudinal compatibility with plesiochronous line systems complying with Recommendations G.955 and G.956, УУrecommends ФФС Сthat digital synchronous line systems comply with the requirements described in the following. 1.2Тh  ТУУAbbreviationsФФЦЦ Та ТТ№ ТС€ СADMСpСAddЉdrop multiplexerЦЦ Та ТТ№ ТС€ СAISСpССи СAlarm indication signalЦЦ Та ТТ№ ТС€ СALSСpССи СAutomatic laser shutdownЦЦ Та ТТ№ ТС€ СBERСpСBit error ratioЦЦ Та ТТ№ ТС€ СBIPЉ8Си СBit Interleaved parity order 8ЦЦ Та ТТ№ ТС€ СCIDСpССи СConsecutive identical digitЦЦ Та ТТ№ ТС€ СDCCСpСData communications channelЦЦ Та ТТ№ ТС€ СDXCСpСDigital crossЉconnectЦЦ Та ТТ№ ТС€ СE/OСpССи СElectrical/opticalЦЦ Та ТТ№ ТС€ СECCСpСEmbedded control channelЦЦ Та ТТ№ ТС€ СI/FСpССи СInterfaceЦЦ Та ТТ№ ТС€ СLOFСpССи СLoss of frameЦЦ Та ТТ№ ТС€ СMCFСpСMessage communications functionЦЦ Та ТТ№ ТС€ СMSЉAISСи СMultiplex section alarm indication signalЦЦ Т№ ТС€ СMUXСpСMultiplexerЦЦ Та ТТ№ ТС€ СNEСpССи СNetwork elementЦЦ Та ТТ№ ТС€ СO/EСpССи СOptical/electricalЦЦ Та ТТ№ ТС€ СOHAСpСOverhead accessЦЦ Та ТТ№ ТС€ СOOFСpСOut of frameЦЦ Та ТТ№ ТС€ СOS/MDСи СOperations system/mediation deviceЦЦ Та ТТ№ ТС€ СPLLСpССи СPhase locked loopЦЦ Та ТТ№ ТС€ СPRBSСи СPseudo random binary sequenceЦЦ Та ТТ№ ТС€ СRSOHСи СRegenerator section overheadЦЦ Та ТТ№ ТС€ СRSTСpССи СRegenerator section terminationЦЦ Та ТТ№ ТС€ СRTGСpСRegenerator timing generatorЦЦ Та ТТ№ ТС€ СSDHСpСSynchronous digital hierarchyЦЦ Та ТТ№ ТС€ СSEMFСи СSynchronous equipment management functionЦЦ Та ТТ№ ТС€ СSMSСpСSDH management subnetworkЦЦ Та ТТ№ ТС€ СSOHСpСSection overheadЦЦ Та ТТ№ ТС€ СSPIСpССи СSDH physical interfaceЦЦ Та ТТ№ ТС€ СSTMЉNСи СSynchronous transport moduleЦЦ Та ТТ№ ТС€ СTMNСpСTelecommunications management networkЦЦ а HH а1.3Тh  ТУУDefinitionsФФЦЦ Та ТС€ HС1.3.1С СУУAgentЦЦ ФФС СSee Recommendation G.784. Та ТС€ HС1.3.2С СУ Уautomatic laser shutdown (ALS)Ф ФУУЦЦ а H аС СФФThe ALS function of an optical line system automatically switches off the transmitter of a regenerator section in case of cable break in this section. Та ТС€ HС1.3.3С СУУBit interleaved parity order 8 (BIPЉ8)ФФЦЦ С СSee Recommendation G.708. Та ТС€ HС1.3.4С СУ Уconsecutive identical digit (CID) immunityФ ФУУЦЦ а H аФФС СThe ability of a digital system component to sustain the occurrence of a digital signal containing a continuous stream of binary ZEROs or ONEs. Та ТС€ HС1.3.5С СУУData communications channel (DCC)ЦЦ ФФС СSee Recommendation G.784. Та ТС€ HС1.3.6С СУУEmbedded control channel (ECC)ФФЦЦ С СSee Recommendation G.784. Та ТС€ HС1.3.7С СУУLoss of frame (LOF)ФФЦЦ С СSee Recommendation G.783. Та ТС€ HС1.3.8С СУУMessage communications function (MCF)ФФЦЦ С СSee Recommendation G.784. Та Т1.3.9Си СУУMultiplex section alarm indication signal (MSЉAIS)ФФЦЦ а HH аС СSee Recommendation G.783. Та ТС€ HС1.3.10С СУУNetwork element (NE)ФФЦЦ С СSee Recommendation G.784. Та ТС€ HС1.3.11С СУУOperations system/mediation device (OS/MD)ФФЦЦ С СSee Recommendation G.784. Та ТС€ HС1.3.12С СУУOut of frame (OFF)ФФЦЦ Та ТSee Recommendation G.783.ЦЦ Та ТС€ HС1.3.13С СУУOverhead access (OHA)ФФЦЦ С СSee Recommendation G.783. Та ТС€ HС1.3.14С СУУRegenerator section overhead (RSOH)ФФЦЦ С СSee Recommendation G.782. Та ТС€ HС1.3.15С СУУRegenerator section termination (RST)ФФЦЦ С СSee Recommendation G.782. Та ТС€ HС1.3.16С СУ Уregenerator timing generator (RTG)Ф ФЦЦ а H аС СThe RTG function provides a timing reference to the outgoing STMЉN signal of a regenerator. This timing reference is derived from the incoming STMЉN signal recovered by the SPI function in normal operation, or from an internal oscillator included in the RTG in case of fault. Та ТС€ HС1.3.17С СУУS/R reference pointsФФЦЦ С СSee Recommendations G.955, G.956 and G.957. Та ТС€ HС1.3.18С СУУSDH management subnetwork (SMS)ФФЦЦ С СSee Recommendation G.784. Та ТС€ HС1.3.19С СУУSDH physical interface (SPI)ФФЦЦ С СSee Recommendation G.782. Та ТС€ HС1.3.20С СУУSection overhead (SOH)ФФЦЦ С СSee Recommendation G.708. Та ТС€ HС1.3.21С СУУSynchronous digital hierarchy (SDH)ФФЦЦ С СSee Recommendation G.707. Та ТС€ HС1.3.22С СУУSynchronous equipment management function (SEMF)ФФЦЦ С СSee Recommendation G.782. Та ТС€ HС1.3.23С СУУSynchronous transport module (STMЉN)ФФЦЦ С СSee Recommendation G.708. Та ТС€ HС1.3.24С СУУTelecommunications management network (TMN)ФФЦЦ С СSee Recommendation M.30.‚У У Та Т2СpСApplicationsФ ФЦЦ а HH а2.1Тh  ТУУSystem typesФФЦЦ а H аС СFigures 2Љ1/G.958 and 2Љ2/G.958 define the reference configurations of the optical line systems specified in this Recommendation and the relationship between Recommendations G.957, G.958 and serie G.780 for their specification. The two following types of applications are identified: Та ТТ№ ТС€ С1)СpСinterЉoffice link, (see Figure 2Љ1/G.958 and РSР 4.2),ЦЦ Та ТТ№ ТС€ С2)СpСintraЉoffice link, (see Figure 2Љ2/G.958 and РSР 4.2).ЦЦ а H аС СThese two figures illustrate the fact that Recommendation G.957 specifies the performance of the components of the optical link, from the electroЉoptic conversion to the optoЉelectronic one, whereas Recommendation G.958 specifies the performance of the optical link connecting two SDH equipments (multiplexer, digital crossЉconnect, addЉdrop multiplexer), including repeaters if any. 2.2Тh  ТУУSystem componentsФФЦЦ С СA digital line system on optical fibre cables at a given bit rate is usually defined as the means used to implement a digital line section at this bit rate. It comprises line section terminating equipment at both ends, optical fibre sections and regenerators (if needed). а H аС СThe basic frame structure of SDH provides the overhead necessary for the operation and maintenance of line systems, and therefore terminal equipment of synchronous line systems will include multiplexing functions. For example, an STMЉ4 or STMЉ16 line system will include a synchronous multiplexer to multiplex the synchronous tributaries. If it is used to implement digital line sections at a given G.702 hierarchy level (e.g. 139 264 kbit/s), it will also include the functions needed to map the plesiochronous tributary into the STMЉ1. The corresponding functions are described in Recommendation G.783. а H аС СIn order not to constrain equipment design and to ensure compatibility between the various options which may be useful to implement, synchronous line systems are defined for the purpose of this Recommendation as the means used to transport an STMЉN stream between the two reference points C of two consecutive synchronous multiplexers (according to the functional description of Recommendation G.783 and assuming that it will also be consistent with future Recommendations on digital crossЉconnect systems РIР DXCs). С СSynchronous line systems therefore comprise the terminating parts of synchronous multiplexers, i.e. from reference point C to reference point A (see Figure 1Љ1/G.783), the optical fibre sections and the regenerators if needed. а H аС СThese components are described in РSР 3 (transmission medium), РSРS 4, 5 and 6 (overall design features, line termination and regenerators). С СWherever possible, references to the relevant parts of Recommendations G.782, G.783 and G.784 are made, in particular in terms of functional organization and information flows. С СThis is also illustrated in Figures 2Љ1/G.958 and 2Љ2/G.958. ‚Ср JСб cмˆ4 PŽТ бFIGURE 2Љ1/G.958 = 7,5 cm = 293 б cмˆ4 PŽТ б Ср KСб cмˆ4 PŽТ бFIGURE 2Љ2/G.958 = 9 cm = 352 б cмˆ4 PŽТ б С СУУNote 1ФФ РIР The figures report functional partitioning, УУnot necessarily physical onesФФ. Та ТУУNote 2ФФ РIР The functional blocks of Recommendation G.783 are not used because the figures are only intended to describe the scope of the various Recommendations related to Recommendation G.958.ЦЦ а H аУУТа ТNoteФФ УУ3ФФ РIР A and C are reference points as described in Figure 1Љ1/G.783. Reference point A is equivalent to S/R reference points of Recommendations G.955 and G.956 (see also Recommendation G.957).ЦЦ‚У У Та Т3СpСType of transmission mediumФ ФЦЦ а H аС СSingle mode optical fibre cables conforming to several Recommendations are allowed in these systems. Recommendation G.652 refers to dispersionЉunshifted fibres, Recommendation G.653 to dispersionЉshifted fibres, and Recommendation G.654 to lossЉminimized fibres. Both the attenuation and dispersion aspects are of particular concern to Recommendation G.957; only the latter are currently well defined in these Recommendations. С СThe wavelength regions are around 1310 nm for G.652 fibre, and around 1550 nm for G.652, G.653, and G.654 fibres. Within these regions, the wavelength ranges are defined first by cutЉoff wavelength and by system attenuation and length requirements. Wavelength ranges are specified in Recommendation G.957 for each application. а H аС СThese fibres may be used with several transmitters; singleЉlongitudinal mode lasers, multiЉlongitudinal mode lasers, and lightЉemitting diodes. Spectral characteristics such as chirp, modeЉpartition noise, and spectral width induce a power penalty, depending upon the fibre dispersion. This will then further limit the operating wavelength ranges. ‚У У4ТX ТOverall design featuresФ ФЦЦ 4.1Тh  ТУУSystem design and optical parametersФФЦЦ а H аС СPrior to the advent of SDH the scope of the design of optical line systems included a large number of parameters such as transmit power range, receiver overload and sensitivity, line code, operating wavelength, operation and maintenance features, etc. This led to a great variety of designs, each having a specific combined optimization of the parameters, the only common parameters being the attenuation and dispersion of the optical path between points S and R. Those systems specified in Recommendations G.955 and G.956 provided only longitudinal compatibility, i.e. the possibility of parallel installation on the same cable route. Interconnection between two operators could be achieved either through joint engineering of the optical link, or interconnection at a hierarchical level. (Joint engineering is defined in РSР 4.3 below.) а H аС СSynchronous line systems described in this Recommendation are intended to provide transverse compatibility, i.e. the possibility of mixing various manufacturers' equipments within a single optical section. This is based on compliance with bit rates, frame structure and detailed mappings as defined in Recommendations G.707, G.708 and G.709, with general characteristics and functionalities as given in Recommendations G.782 and G.783, and with operation and maintenance as specified in Recommendation G.784. С СFor the optical parameters of the interfaces used in synchronous line systems, transverse compatibility is based on compliance with Recommendation G.957. Recommendation G.957 is summarized in РSР 4.2. 4.2Тh  ТУУTransverse compatibility ФФ(Recommendation G.957)ЦЦ С СRecommendation G.957 (Optical interfaces for equipments and systems relating to the synchronous digital hierarchy), provides specifications for the optical interfaces of SDH equipment, described in Recommendations G.782 and G.783, and line systems described in the present Recommendation, to achieve the possibility of transverse compatibility on elementary cable sections, i.e. mixing various manufacturers' equipments within a single optical section. These specifications also provide longitudinal compatibility with line systems of comparable hierarchical level and application which are in accordance with Recommendations G.955 and G.956. С СThe applications belong to these three categories with regard to the achievable repeater span: Та ТРIРТ№ ТintraЉoffice for distances less than approximately 2 km;ЦЦ а HX аТа ТРIРТ№ ТshortЉhaul interЉoffice for distances of approximately 15 km;ЦЦ а H аТа ТРIРТ№ ТlongЉhaul interЉoffice for distances of approximately 40 km or more.ЦЦ а H аС СWithin each category further subdivisions are made depending on the fibre type and wavelength region as described in РSР 3 above. This leads to one intraЉoffice specification, two interЉoffice shortЉhaul specifications and three interЉoffice longЉhaul specifications for each bit rate. а H аС СFor each application separate specifications are given for the transmitter at point S, the receiver at point R and the optical path between S and R. а H аС СRecommendation G.957 also contains the definition of each parameter used. Corresponding measurement methods are under study and should eventually be included in Recommendation G.957. а H аС СThe relationship between the parameters of the constituents of the optical link is also described in Recommendation G.957 РSР 5 in order to establish a а H аa common system design approach for engineering SDH optional links. This can be used to select a suitable interface for a given regenerator section, depending on the characteristics of the optical path of this section. а H аС СIt should be noted that the specifications given in Recommendation G.957 are based on worstЉcase parameter values to provide simple design guidelines for network planners and explicit component specifications for manufacturers. It is recognized that, in some cases, this may lead to more conservative design than could be obtained through joint engineering of the optical link, the use of statistical equipment design approaches (statistical and semi-statistical design approaches are described in Recommendation G.957), or in applications and environments more constrained than those permitted under the standard operating conditions. а H а С СIt is believed that this approach is sufficient to meet the requirements of the great majority of cases. РSР 4.3 below discusses those cases where there is a need for an improved level of performance. 4.3Тh  ТУУJoint engineeringФФЦЦ а H аС СFor a limited number of cases joint engineering may be envisaged to meet the requirements of optical sections where the interface specifications of Recommendation G.957 prove inadequate. This will probably occur where the required section loss is greater (e.g. 2 dB) than that specified in Recommendation G.957 but may also be considered for other parameters. а H аС СFor those cases it is up to the Administrations/operators concerned to specify more closely the aspects of the system where the specifications of Recommendation G.957 are not satisfactory. It is important to stress that every situation requiring Р"Рjoint engineeringР"Р is likely to be different РIР hence it is meaningless to try to standardize any of the parameter values for these systems. Instead, it is for the Administrations/operators concerned to come to an agreement as to what is required and then negotiate with manufacturers as to what is actually feasible. This process is very likely to lead to both ends of a transmission link being supplied by the same manufacturer, who meets the required performance by jointly optimizing the transmitters and receivers. а H аС СIt should be pointed out that, in spite of the futility of specifying any parameter values for Р"Рjointly engineeredР"Р systems, it would be advisable for Administrations/operators or manufacturers involved to follow the general guidelines and system engineering approach used in Recommendation G.957. In particular it would be helpful to use the same parameter definitions as Recommendation G.957 (e.g. receiver sensitivity at R reference point including all temperature and aging effects). 4.4Тh  ТУУPattern dependence testingФФЦЦ а H аС СSTMЉN signals contain regions within the data stream where the possibility of bit errors being introduced is greater due to the structure of the data within these regions. С СThree cases in particular may be identified: а H аТа ТТ№ ТС€ С1)СpСerrors resulting from eyeЉclosure due to the tendency for the mean level of the signal within the equipment to vary with patternЉdensity due to alternative current couplings (Р"РDC wanderР"Р);ЦЦ а H аТа ТТ№ ТС€ С2)СpСerrors due to failure of the timing recovery circuit to bridge regions of data containing very little timing information in the form of data transitions;ЦЦ а H аТа ТТ№ ТС€ С3)СpСerrors due to failure of the timing recovery circuit as in 2) above but compounded by the occurrence of the first row of the STMЉN section overhead bytes preceding a period of low timing content (these bytes have low data content, particularly for large N).ЦЦ а H аС СIn order to verify the ability of STMЉN equipment to operate errorЉfree under the above conditions, a possible method to assess the consecutive identical digit (CID) immunity of a circuit block is presented in Appendix I. а H аС СThis method may be employed during the design phase of the equipment and appropriate points in the production assembly process. ‚У У5ТX ТTransmission overheadsФ ФЦЦ а H аС СThis section describes the regenerator section overhead (RSOH) processing functionality in a synchronous line system. The definition of a regenerator section (see Figure 5Љ1/G.958 below) and the functional description of a regenerator (see Figure 5Љ2/G.958 below) are based on the functional block description of Recommendation G.783. The functional blocks and the signals are а H аbiЉdirectional where necessary. These descriptions are logical descriptions, not suggested implementations. 5.1Тh  ТУУRegenerator section modelФФЦЦ С СThe regenerator section model is illustrated in Figure 5Љ1/G.958. The definitions of the functions and signals at reference points are given in Recommendation G.783. а H аС СA regenerator section is defined as the part of an SDH link between two adjacent reference points C, i.e. where the RSOH is generated and included in the STMЉN frame and where the RSOH is extracted from the STM-N frame and terminated. Regenerator section end equipments may be multiplexers (or cross-connect systems) and/or regenerators. In case of intraЉoffice links both ends are multiplexers (or DXCs).‚б cмˆ4 PŽТ б Ср JСFIGURE 5Љ/1G.958 = 12 cm = 469 б cмˆ4 PŽТ б  5.2Т№  ТУУRegenerator model and functionalityФФЦЦ а H аС СThe regenerator model is shown in Figure 5Љ2/G.958. The functional blocks and the signals at the reference points are the same as those described in Recommendation G.783, except where noted below. а H аС СIn the following description, signal flows from left to right of Figure 5Љ2/G.958. а H аС СThe signal at reference point A(1) is the STMЉN line signal. Reference point A(1) physically corresponds to reference point R in Recommendations G.955 and G.956. The characteristics of the optical signal at this reference point are given in Recommendation G.957. а H аС СSTMЉN signal entering at reference point A(1) is electrically regenerated by the SDH physical interface function SPI(1) at reference point B(1). ‚Ср IСб cмˆ4 PŽТ бFIGURE 5Љ2/G.958 = 11,5 cm = 449 б cмˆ4 PŽТ б а H аС СSPI(1) converts the signal at reference point A(1) into the sequence of logical levels forming the signal at reference point B(1), for which SPI(1) must grant the characteristics necessary to meet the required transmission and network performance. Transmission performance requirements for synchronous optical systems are given in РSРS 6 and 7 and the network performance requirements are given in Recommendation G.782. Timing is extracted from the incoming signal and is made available at reference point T1 to the regenerator timing generator (RTG), and at reference point B(1) to the RST(1). RTG requirements are contained in РSР 6. С СThe status of the received signal is monitored to detect input signal failures. Input signal fail conditions and related parameters are defined in РSР 7. С СThe signal fail condition is reported to the synchronous equipment management function (SEMF) through reference point S1 and to RST(1) through reference point B(1). The SEMF monitors all the regenerator functions for management and control as described in РSР 5.2.5. а H аС СThe RST(1) function recovers the frame alignment from the fully formatted and regenerated STMЉN data and associated timing at B(1). Criteria for а H аframe alignment algorithm, for outЉofЉframe condition (OOF), loss of frame state (LOF) and the associated reporting to SEMF through the S2 reference point are described in Recommendation G.783. С СThen the RST(1) function descrambles the signal at B(1), using the recovered frame alignment and extracts the RSOH bytes. Scrambling in the regenerator is described in РSР 5.2.1. а H аС СIn an STMЉN frame, the use of only a subset of the RSOH bytes is defined. The definitions of these bytes and their positions in the STMЉN frame are given in Recommendation G.708 and described in detail for SDH equipment in Recommendation G.783. In this section of Recommendation G.958 features specific to regenerators of synchronous line systems are described. а H аС СThe B1 byte is used to locate faulty regenerator sections. The B1 byte is monitored and the result is reported to SEMF through reference point S2. а H аС СByte E1 provides an orderwire voice channel between section terminations. Byte E1 is passed to the overhead access (OHA) function at reference point U1. The OHA function in the regenerator provides the means for accessing specific overhead capacities in RSOH. In the case of a 1:N line protection system, it is not necessary for all regenerators within the same repeater station to access the orderЉwire signal. а H аС СThe F1 byte is the user channel and is also passed to the OHA function. The access of the user channel in the regenerator is optional. An example of use of the F1 byte to identify a failed section in a chain of regenerator sections is reported in Recommendation G.783. а H аС СData communication channels (DCC) bytes D1ЉD3 are routed to the message communication function (MCF) through reference point N. The use of DCC is described in Recommendations G.783 and G.784. С СRegenerators should be capable of ignoring the national use bytes and bytes reserved for future international standardization. а H аС СThe RST function might need to access other bytes for medium dependent use (see РSР 5.2.3 below). С СThe signal at reference point C is an STMЉN frame with the associated timing signal. The RST(2) function inserts RSOH bytes to the data at reference point C, performs the scrambling and presents the fully formatted STMЉN data to SPI(2) at reference point B(2). а H аС СThe RSOH bytes to be inserted are generated at RST(2), taken either from the OHA through reference point U1 or from the MCF through reference point N, or relayed from RST(1). С СUnder normal operation (i.e. inЉframe condition at RST(1)): а H аТа ТРIРТ№ ТA1, A2 and C1 bytes are either generated or relayed. Relaying the received framing bytes reduces the delay in the detection of OOF and recovery from failure in a chain of regenerators. Fault sectionalization capability is not affected because B1 is recalculated for each regenerator section. From a management viewpoint, it is preferable that all the regenerators in a line system conform to either one or other approach;ЦЦ Та ТРIРТ№ Т B1 is generated as described in Recommendation G.783;ЦЦ а Hx аТа ТРIРТ№ ТE1 and F1 are taken from the OHA; optionally they may be relayed;ЦЦ Та ТРIРТ№ ТD1ЉD3 are taken from the MCF;ЦЦ а Hh аТа ТРIРТ№ Тnational use bytes and bytes reserved for future international standardization in the RSOH are either relayed or generated as described in Recommendation G.783.ЦЦ а HH аС СWhen RST(1) is in a failure state described in РSР 5.2.2: Та ТРIРТ№ ТA1, A2 and C1 are generated;ЦЦ Та ТРIРТ№ Т B1 is generated as described in Recommendation G.783;ЦЦ Та ТРIРТ№ ТE1 and F1 are taken from the OHA;ЦЦ Та ТРIРТ№ ТD1ЉD3 are taken from the MCF;ЦЦ а Hh аТа ТРIРТ№ Тnational use bytes and bytes reserved for future international standardization in the RSOH are generated as specified in Recommendation G.783.ЦЦ а H аС СWhen RST(1) is in OOF condition (but not in a failure state as described in РSР 5.2.2) all RSOH bytes may be relayed. а H аС СSPI(2) converts the logical levels of the signal at reference point B(2) into optical pulses at reference point A(2). The SPI function must provide the characteristics of the signal necessary to meet the required transmission and network performance. Reference point A(2) physically corresponds to reference point S in Recommendations G.955 and G.956. The characteristics of the optical signal at this reference point is given in Recommendation G.957. Parameters related to the status of the transmitter are sent to SEMF through reference point S1. Parameters to be monitored are defined in РSР 7. Та ТС€ HС5.2.1С СУУScrambling in the regeneratorФФЦЦ а H аС СIn order to clearly define the scrambling and descrambling processes, a functional diagram of the signal path in the RST is shown in Figure 5Љ3/G.958, according to the algorithm reported in Recommendation G.709. а H аС СThe upper part shows the transmission side of RST. Firstly the complete STMЉN frame, including B1 byte computed on the previous frame, is built, the STMЉN frame is then scrambled, except for the first SOH row, i.e. the first N РР 9 bytes, and finally the BIPЉ8 is computed over the entire scrambled frame. The BIPЉ8 value will be included in the next frame as B1 byte. С СSimilarly the central part shows the receive side of RST. Before descrambling, frame alignment is searched or verified on the received STMЉN signal and BIPЉ8 is computed. Then the STMЉN frame is descrambled, except for а H аthe first SOH row, i.e. the first N РР 9 bytes, and the RSOH is subsequently used, including B1 byte. С СThe lower part of the Figure 5Љ3/G.958 shows the entire STMЉN frame. а H аС СThis description is only functional, and does not imply any particular physical implementation. The regenerator has to access only the RSOH bytes, and in principle needs to descramble and scramble only these bytes. Therefore data at C to be passed from RST(1) to RST(2) may actually be passed transparently from B(1) to B(2) rather than being descrambled at RST(1) and scrambled at RST(2). Та ТС€ HС5.2.2С СУУAlarm indication signal (AIS)ФФЦЦ а H аС СUnder the failure cases mentioned in Recommendation G.783 (i.e. loss of signal or loss of frame), resulting in a logical all ONES signal at reference point C, the signal at C and valid RSOH added at B(2) results in an MSЉAIS. Recommendation G.783 specifies the delay to activate and deactivate MSЉAIS. Та ТС€ HС5.2.3С СУУMedium dependent use of overhead bytesФФЦЦ а H аС СIt is possible that in the future some bytes may be dedicated to functions specific to a particular transmission medium. These bytes could be taken from those reserved for national use and future international standardization. Otherwise bytes already defined could be modified in their use to include medium specific requirements. а H аС СAs an example the need for and implementation of a function to identify the signal direction in biЉdirectional optical transmission over a single fibre is for further study. Та ТС€ HС5.2.4С СУУIntraЉoffice linkФФЦЦ С СReduced functionalities to be used in intraЉoffice link regenerator sections are for further study. Та ТС€ HС5.2.5С СУУManagementФФЦЦ а H аС СThe general SDH control and management principles and the interworking with TMN illustrated in Recommendation G.784 apply to the regenerator. The SDH management architecture, the communication network structure among different network elements (NE) and a model for the regenerator are shown in Recommendation G.784.‚б cмˆ4 PŽТ б Ср IСFIGURE 5Љ3/G.958 = 15,5 cm = 606 б cмˆ4 PŽТ б С СThe regenerator includes a SEMF. It contains a number of filtering functions that translate primitive information, coming from the functional blocks, to forms usable by the network management and vice versa. Some information is not processed by a filtering function. The filtering functions used in a regenerator are described in detail in Recommendation G.783. The possible use of internal storage for performance parameters history retrieval, the ability of generating autonomous alarm reports on threshold crossings and the possibility of setting externally the threshold values are described in Recommendation G.784. In the regenerator an Agent is present in the SEMF, а H аwhich controls the exchange of information with other SDH network elements or with the TMN for management purposes. Characteristics of the Agent are given in Recommendation G.784. а H аС СMessages are sent over the embedded control channel (ECC) that utilizes DCC, i.e. D1ЉD3 bytes as the physical layer. The protocol stack used and а H аthe message generation and termination methods are described in Recommendation G.784. С СMessages are transmitted and received by the message communication function (MCF), which is connected to the SEMF through V reference point and to a Q interface when provided. а H а С СIncoming bytes D1ЉD3 are extracted by the RST function and routed to the MCF through reference point N. Relayed messages and locally generated messages are sent through reference point N as D1ЉD3 bytes to the RST function, which inserts them into the RSOH of the outgoing STMЉN frame. а H аС СTwo interfaces towards elements external to the SDH network may be used. The Q interface can connect the regenerator to an operation а H аsystem/mediation device (OS/MD). The F interface may be used to connect the regenerator to a workstation for monitoring and maintenance purposes. 5.3Тh  ТУУRegenerator interfacesФФЦЦ С СThe regenerator has the following interfaces: Та ТРIРТ№ ТS reference point on both transmitting fibres: the interface characteristics at this reference point are specified in Recommendation G.957;ЦЦ Та ТРIРТ№ ТR reference point on both receiving fibres: the interface characteristics at this reference point are specified in Recommendation G.957;ЦЦ Та ТРIРТ№ Тinterface for orderwire channel: to be defined;ЦЦ Та ТРIРТ№ Тinterface for user channel: to be defined;ЦЦ Та ТРIРТ№ Тuse of a Q interface may be foreseen in some applications;ЦЦ а H аТа ТРIРТ№ ТF interface to a workstation: its characteristics are under study.ЦЦ а HH а‚У У6ТX ТGeneral characteristics of synchronous optical line systemsФ ФЦЦ 6.1Тh  ТУУSynchronization and timing signalФФЦЦ а H аС СThe structure and details of synchronization and timing signals are described in Recommendation G.782. 6.2Тh  ТУУRegenerator timingФФЦЦ а H аС СFigure 6Љ1/G.958 illustrates the timing functions for regenerators. The regenerator timing generator (RTG) includes an internal oscillator. In normal operation, the SPI function recovers the timing from the incoming STM-N signal at reference point A and passes the data and timing to RST at reference point B, and passes the timing signal also to the RTG function at reference point T1. The RTG function provides the timing signal to the outgoing STMЉN signal at reference point T0. The directionality of the timing signals is maintained. а H аС СWhen transmitting MSЉAIS the RTG shall provide timing for the outgoing STMЉN signal at reference point T0 using the internal oscillator. The longЉterm frequency stability of the internal oscillator in freeЉrunning mode shall be equal to or better than РР 20 ppm. а H аС СThe RTG and SPI functions must accommodate timing from an incoming MS-AIS signal. 6.3Тh  ТУУJitter performanceФФЦЦ а H аС СThis section deals with jitter requirements for optical interfaces at the STMЉN levels as defined in Recommendation G.707. Specifications for multiplex jitter and wander at STMЉN and Recommendation G.703 interfaces are described in Recommendations G.782 and G.783.‚ а H аС СThe purpose of the jitter requirements in these sections is to control the accumulation of jitter within SDH line systems. SDH line equipment jitter specifications are organized into limits for the following: jitter generation, jitter transfer and jitter tolerance. Та ТС€ HС6.3.1С СУУJitter generationФФЦЦ а H аС СJitter generation is defined as the amount of jitter at the STMЉN output of SDH equipment. а H а С СAn SDH regenerator shall not generate more than 0.01 UI RMS jitter, with no jitter applied at the STM-N input. The measurement bandwidth and technique are under study. Та ТС€ HС6.3.2С СУУJitter transferФФЦЦ С СJitter transfer specification applies only to SDH regenerators. С СThe jitter transfer function is defined as the ratio of jitter on the output STMЉN signal to the jitter applied on the input STMЉN signal versus frequency. С СThe jitter transfer function of an SDH regenerator shall be under the curve given in Figure 6Љ2/G.958, when input sinusoidal jitter up to the mask level in Figure 6Љ3/G.958 is applied, with the parameters specified for Type A in Table 1/G.958 for each bit rate. ‚Ср NСб cмˆ4 PŽТ бFIGURE 6Љ2/G.958 = 7 cm б cмˆ4 PŽТ б а H аС СIf an SDH regenerator meets the jitter transfer specification for Type B, it is classified as Type B regenerator. ‚Ср KСб cмˆ4 PŽТ бinclude 958ЉT01ETABLE 1/G.958 Ср LСУ УJitter transfer parametersФ Ф б cмˆ4 PŽТ бвЦƒHши Ј ˜ hЦв‡аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаадаСр QСааб cмˆ4 PŽТ бSTM level (type) аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџH0 ˜ hџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр UСУУfУУб cмˆ4 PŽТ бcФФ (kHz)б cмˆ4 PŽТ бФФ аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџH№XР(џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр VСУУPФФ (dB) а ˜  ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ˜ №XР(џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бˆа ˜  аб cмˆ4 PŽТ бвЦƒHши Ј ˜ hЦв‡а ˜ А ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџpи ˜ џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр№@Сб cмˆ4 PŽТ бSTMЉ1 (A) а P И ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџP 0 ˜ hџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаС`И С130 аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџP №XР(џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСрШ .С0.1 а ˜  ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ˜ №XР(џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бˆа ˜  аб cмˆ4 PŽТ бвЦƒHши Ј ˜ hЦв‡а ˜ А ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџpи ˜ џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр№@Сб cмˆ4 PŽТ бSTMЉ1 (B) а P И ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџP 0 ˜ hџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаС`И С30 аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџP №XР(џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСрШ .С0.1 а ˜  ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ˜ №XР(џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бˆа ˜  аб cмˆ4 PŽТ бвЦƒHши Ј ˜ hЦв‡а ˜ А ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџpи ˜ џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр№@Сб cмˆ4 PŽТ бSTMЉ4 (A) а P И ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџP 0 ˜ hџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаС`И С500 аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџP №XР(џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСрШ .С0.1 а ˜  ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ˜ №XР(џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бˆа ˜  аб cмˆ4 PŽТ бвЦƒHши Ј ˜ hЦв‡а ˜ А ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџpи ˜ џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр№@Сб cмˆ4 PŽТ бSTMЉ4 (B) а P И ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџP 0 ˜ hџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаС`И С30 аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџP №XР(џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСрШ .С0.1 а ˜  ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ˜ №XР(џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бˆа ˜  аб cмˆ4 PŽТ бвЦƒHши Ј ˜ hЦв‡а ˜ 8 ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџpи ˜ џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСрhAСб cмˆ4 PŽТ бSTMЉ16 (A) а P И ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџP 0 ˜ hџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаС`И С200 С`И С0 аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџP №XР(џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСрШ .С0.1 а ˜  ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ˜ №XР(џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бˆа ˜  аб cмˆ4 PŽТ бвЦƒHши Ј ˜ hЦв‡а ˜ 8 ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџpи ˜ џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСрhAСб cмˆ4 PŽТ бSTMЉ16 (B) а P И ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџP 0 ˜ hџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаС`И С30 аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџP №XР(џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСрШ .С0.1 а ˜  ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ˜ №XР(џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бˆа HH ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџH јP Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬааа аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи P Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаТа ТС€ HС6.3.3С СУУJitter toleranceФФЦЦ а H аС СJitter tolerance is defined as the peakЉtoЉpeak amplitude of sinusoidal jitter applied on the input STM-N signal that causes a 1 dB optical power penalty at the optical equipment. Note that this is a stress test to ensure that no additional penalty is incurred under operating conditions. This technique is described in Supplement No. 3.8 of the OЉSeries Recommendations.‚б cмˆ4 PŽТ б Ср JСFIGURE 6Љ3/G.958 = 7,5 cm = 293 б cмˆ4 PŽТ б С СSDH equipment shall tolerate, as a minimum, the input jitter applied according to the mask in Figure 6-3/G.958, with the parameters specified in Table 2/G.958 for each bit rate. С СIn a line system using Type A regenerators, the SDH regenerators and terminal shall meet Type A jitter tolerance specification. In a line system using Type B regenerators, the SDH regenerators and terminals shall meet Type B jitter tolerance specifications. In this case a terminal or regenerators meeting Type A jitter tolerance specifications may also be used. In a line system without regenerators, the SDH terminal shall meet either Type A or Type B jitter tolerance specifications. The use of regenerators of Type A and Type B within the same line system is for further study. ‚Ср KСб cмˆ4 PŽТ бinclude 958ЉT02ETABLE 2/G.958 Ср LСУ УJitter tolerance parametersФ Ф б cмˆ4 PŽТ бвЦ…Hши Ј ˜ hX( шЦв‡аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаадаСр RСб cмˆ4 PŽТ бSTM leve (type) аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџH0 ˜ hџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр UСУУfУУб cмˆ4 PŽТ бtФФ б cмˆ4 PŽТ бФФ(kHz) аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџH№XР(џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр UСУУfФФУУб cмˆ4 PŽТ б0б cмˆ4 PŽТ бФФ (kHz) аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHА€pџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр TСУУAФФУУб cмˆ4 PŽТ б1 б cмˆ4 PŽТ бФФ(UIpЉp) Ср TСУУAФФУУб cмˆ4 PŽТ б2 б cмˆ4 PŽТ бФФ(UIpЉp) а  ˆ ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџА €pџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бˆа  ˆ аб cмˆ4 PŽТ бвЦ…Hши Ј ˜ hX( шЦв‡а  Ј ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџpи  џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр,ј^Сб cмˆ4 PŽТ бSTMЉ1 (A) а P И ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџP 0 ˜ hџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаС`И С65 а P P ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџP №XР(џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСрИ 0С126.5 аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџP А€pџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСрИ 0С0.15 СрИ 1С1.5 а  ˆ ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџА €pџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бˆа  ˆ аб cмˆ4 PŽТ бвЦ…Hши Ј ˜ hX( шЦв‡а  Ј ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџpи  џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр,ј^Сб cмˆ4 PŽТ бSTMЉ1 (B) а P И ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџP 0 ˜ hџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаС`И С12 а P P ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџP №XР(џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСрИ 0С121.2 аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџP А€pџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСрИ 0С0.15 СрИ 1С1.5 а  ˆ ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџА €pџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бˆа  ˆ аб cмˆ4 PŽТ бвЦ…Hши Ј ˜ hX( шЦв‡а  Ј ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџpи  џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр,ј^Сб cмˆ4 PŽТ бSTMЉ4 (A) а P И ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџP 0 ˜ hџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаС`И С250 аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџP №XР(џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСрШ .С25 а P Ш ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџP А€pџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр@ /С0.15 Ср@ 0С1.5 а  ˆ ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџА €pџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бˆа  ˆ аб cмˆ4 PŽТ бвЦ…Hши Ј ˜ hX( шЦв‡а  Ј ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџpи  џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр,ј^Сб cмˆ4 PŽТ бSTMЉ4 (B) а P И ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџP 0 ˜ hџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаС`И С12 а P P ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџP №XР(џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСрИ 0С121.2 аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџP А€pџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСрИ 0С0.15 СрИ 1С1.5 а  ˆ ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџА €pџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бˆа  ˆ аб cмˆ4 PŽТ бвЦ…Hши Ј ˜ hX( шЦв‡а  0 ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџpи  џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр,p_Сб cмˆ4 PŽТ бSTMЉ16 (A) а P И ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџP 0 ˜ hџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаС`И С100 С`И С0 аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџP №XР(џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСрШ .С100 а P Ш ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџP А€pџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр@ /С0.15 Ср@ 0С1.5 а  ˆ ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџА €pџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бˆа  ˆ аб cмˆ4 PŽТ бвЦ…Hши Ј ˜ hX( шЦв‡а  0 ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџpи  џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр,p_Сб cмˆ4 PŽТ бSTMЉ16 (B) а P И ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџP 0 ˜ hџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаС`И С12 а P P ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџP №XР(џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСрИ 0С121.2 аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџP А€pџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСрИ 0С0.15 СрИ 1С1.5 а  ˆ ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџА €pџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бˆа HH ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџH јP Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬааааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи P Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬа Та Т6.4СpСУУError performanceФФЦЦ а H аС СThe synchronous line systems specified in this Recommendation should meet the relevant performance objectives of Recommendation G.821 under the worst environmental conditions. In particular they are required to provide at а H аleast error performance in accordance with Р"Рsection quality classification 1Р"Р, defined in Recommendation G.821. 6.5Тh  ТУУAvailability and reliabilityФФЦЦ С СFor further study. 6.6Тh  ТУУEnvironmental conditionsФФЦЦ С СFor further study. 6.7Тh  ТУУLaser safetyФФЦЦ С СFor safety considerations, according to ReferenceУУ ФФ[1] or national regulations, it may be necessary to provide for an automatic laser shutdown (ALS) facility of the laser in case of cable break. С СThis function is considered as optional. а H аС СAppendix II shows the required functionality of automatic laser shutdown when implemented. а H аС СIn case automatic laser shutdown facility is implemented the following Command, Configuration & Provisioning information will flow over the S1 reference point (refer to Table 5Љ12/G.783): ‚Ср QСб cмˆ4 PŽТ бinclude 958ЉT03E б cмˆ4 PŽТ бвЦƒHˆЦв‡аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаадаСр TСб cмˆ4 PŽТ бSЉInterface аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџH` Ш 0 ˜ џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр XСGet Ср XСSet а ˆh ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ` Ш 0 ˜ ˆџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бˆа ˆh аб cмˆ4 PŽТ бвЦƒHˆЦв‡аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџpи ˆџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бS1 аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ` Ш 0 ˜ ˆџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаALS implemented а ˆ аALS enabled/disabled Tx output on/off ALS enabled/disabled Tx output on/off а ˆh аб cмˆ4 PŽТ бˆа HH ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџH јP Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬааа а H ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи P Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаС СIf automatic laser shutdown is implemented it should not impair fault sectionalization capability in case of loss of signal at the transmitter or the receiver due to causes other than a cable break. ‚У У7ТX ТOperational overviewФ ФЦЦ 7.1Тh  ТУУOverviewФФЦЦ С СThe operation, administration and maintenance features of digital synchronous line systems should be designed in accordance with Recommendations M.20 (Maintenance philosophy for telecommunication networks), M.30 (Principles for a telecommunications management network) and G.784 (SDH management). С СIn particular management principles should be based on the concepts defined in Recommendation M.30: а H№ аТа ТРIРТ№ Тfunctional organization of management functions (configuration, performance, faults),ЦЦ а Hр аТа ТРIРТ№ Тfunctional description of network elements in managed objects.ЦЦ а H аС СThe synchronous line system may be considered from the point of view of management as a SDH Management SubЉnetwork (SMS as defined in Recommendation G.784). The architecture, embedded control channel (ECC) functions, information model and ECC protocols should therefore conform to the specifications given in Recommendation G.784. а H аС СIn particular the information model should follow the specifications given in Recommendation G.784. С СIt should also be noted that synchronous line systems defined in this Recommendation should provide autonomous management functions (performance monitoring, fault location, alarm generation) for early implementations where the connection to a TMN is not possible. The way in which this could be done while retaining forward compatibility with the full deployment of TMN features is for further study. 7.2Тh  ТУУGeneral management functionsФФЦЦ С СThe synchronous line systems should provide the general management functions described in Recommendation G.784. 7.3Тh  ТУУFault (maintenance) managementЦЦ а H аФФС СThe synchronous line systems should support the fault management functions described in Recommendation G.784. Та ТС€ HС7.3.1С СУУAlarm surveillanceФФЦЦ С СThis section describes parameters which should be monitored in the synchronous line systems. In general, these parameters are monitored to assist with fault localization. They are not intended to act as the primary indication of link failure. Та ТС€ HС7.3.1.1СpСУУParameters to be monitored at the S1 reference pointФФЦЦ Та ТС€ HС7.3.1.1.1СpСУУSignal status (transmitter)ФФЦЦ а H аС СThis parameter should indicate whether the transmitter power level is in the range specified in Recommendation G.957 for the defined application code. It will therefore have two values: within range, and out of range. Some form of hysteresis and integration time has to be provided (for further study). It is recognized, that without the use of a coupler and additional detector, the only parameter that can give an indication of the transmitter output power is the current passing through the laser back-facet monitor diode. Under certain fault conditions, the circuit controlling this current may mask significant variations in the laser output power. The exact power level at which this parameter takes on the value Р"Рout of rangeР"Р is not specified. The purpose of monitoring this parameter is to indicate whether a serious fault exists in the transmitter. Та ТС€ HС7.3.1.1.2СpСУУLoss of incoming signalФФЦЦ а H аС СThis parameter should take on the value Р"Рincoming signal absentР"Р when the incoming power level at the receiver has dropped to a level which is lower than that required to cause a BER of 1 in 10УУб cмˆ4 PŽТ бЉ3ФФб cмˆ4 PŽТ б. The purpose of monitoring this parameter is to indicate either: Та ТТ№ ТС€ Сi)СpСtransmitter failure,ЦЦ Та ТТ№ ТС€ Сii)СpСoptical path break.ЦЦа HH а Та Т7.3.1.1.3СЈ СУУLaser biasФФЦЦ а H аС СThis parameter should be used to monitor the bias current of the laser of the transmitter. The purpose of monitoring this parameter is to indicate laser degradation well in advance of catastrophic failure of the link. The value at which this parameter takes on the value Р"Рbias out of limitsР"Р is not specified. Та ТС€ HС7.3.1.1.4СpСУУLaser temperatureФФЦЦ а H аС СThis parameter can have the values Р"Рtemperature within range/temperature out of rangeР"Р. The purpose of monitoring this parameter is to indicate failure of the transmitter temperature control circuitry. The value at which this parameter takes on the value Р"Рtemperature out of rangeР"Р is not specified. Та ТС€ HС7.3.1.2СpСУУParameters to be monitored at the S2 reference pointФФЦЦ С СThe corresponding requirements are contained in Recommendation G.783. Та ТС€ HС7.3.2С СУУTestingФФЦЦ Та ТС€ HС7.3.2.1СpСУУLoopbacksФФЦЦ а H аС СIt is considered that the loss of signal indications at the receiver and at the transmitter provide sufficient resolution for practical fault sectionalization and that loopbacks, optical or otherwise, are not necessary. а H аС СThe need for test points or loopbacks for testing purposes is under study. Та ТС€ HС7.3.3С СУУExternal eventsФФЦЦ а H аС СThis point concerns the case where there is a need to monitor through the synchronous line system site related alarms (door opening or fire in an unmanned station, etc.) or more generally a nonЉSDH network element. The corresponding implementation and requirements are under study. 7.4Тh  ТУУPerformance managementФФЦЦ а H аС СThe synchronous line systems should support the performance management functions described in Recommendation G.784. а H аС СThese functions should be implemented using information flows at reference points S1 and S2 and filtering functions described in Recommendation G.783. 7.5Тh  ТУУTMN interfacesФФЦЦ а H аС СSynchronous line systems should provide at least one interface at each end conforming to Recommendation G.773. 7.6Тh  ТУУOrderwireФФЦЦ а H аС СThe E1 byte may be used for conferencing between line terminal stations and/or regenerator stations. The E2 byte may be used for express pointЉtoЉpoint communication between terminal stations. а H аС СThe definition of orderwire ports and associated signalling procedures is not in the scope of this Recommendation.‚б cмˆ4 PŽТ б Ср TСAPPENDIX I Ср MСб cмˆ4 PŽТ б(to Recommendation G.958) Ср BСУ УImplementation of the cid immunity measurementФ Ф УУС СSummaryФФ а H аС СAlternating digital signal patterns may be used to verify the adequacy of timingЉrecovery and lowЉfrequency performance of STMЉN equipments. а H аС СAppropriate pattern sequences are defined below and in Figure IЉ1/G.958. а H аС СThis test does not attempt to simulate conditions which may occur under anomalous operating conditions to which the equipment may be subjected. УУС СDescriptionФФ а H аС СThe specific test patterns are made up of consecutive blocks of data of four types: а Hh аТа ТТ№ ТС€ Сa)СpСall 1s (zero timing content, high average signal amplitude);ЦЦ Та ТТ№ ТС€ Сb)СpСpseudoЉrandom data with a markЉdensity ratio of 1/2;ЦЦ а Hр аТа ТТ№ ТС€ Сc)СpСall 0s (zero timing content, low average signal amplitude);ЦЦ а H аТа ТТ№ ТС€ Сd)СpСa data block consisting of the first row of section overhead bytes for the STMЉN system under test.ЦЦ а H аС СThe test pattern is shown in Figure IЉ1/G.958 where the regions A, B, C and D are identified. ‚Ср JСб cмˆ4 PŽТ бFIGURE IЉ1/G.958 = 6,5 cm = 254 б cмˆ4 PŽТ б а H аС СThe duration of the zeroЉtimingЉcontent periods A and C is made equal to the longest likeЉelement sequences expected in the STMЉN signal. A value of 9 bytes (72 bits) is provisionally proposed for this. а H аС СThe duration of the pseudoЉrandom periods should allow recovery of both the zero base line offset of the signal and of the timing recovery circuit following occurrence of the A and C periods. Therefore it should be longer than the longest time constant in the regenerator. In the case of a PLL based clock extraction this could give a value of the order of 10 000 bits. Taking into account possible limitations of test equipment a minimum value of 2000 bits is considered acceptable. С СThe content of the pseudoЉrandom section should be generated by a scrambler having the same polynomial as defined in CCITT Recommendation G.709. Ideally, the scrambler should Р"РfreeЉrunР"Р i.e. the beginning of the pattern should be uncorrelated with the frame alignment section. This arrangement will ensure that the system experiences the worst possible phasing of the PRBS at some point during the course of the test. However it is recognized that test equipment limitations may preclude the use of a free running scrambler. Hence it may be necessary to specify a worstЉcase phasing of the PRBS. This is for further study. а H аС СThe D period is defined as the first row of the section overhead of the STMЉN signal, including valid C1 bytes (consecutive binary numbers). С СIt is recommended that this test be applied to SDH systems at any appropriate point in time during the design or production phase. This would be done to demonstrate the ability of both timingЉrecovery and decision circuits adequately to handle worstЉcase SDH signals. а H аС СIt should be emphasized that the test pattern may be rejected by or cause malfunction of certain equipments because, for example, the occurrence of the frame alignment bytes within the pattern. The test should therefore only be used for assemblies not so affected, such as timing recovery units, receiver amplifier chains, etc. а H а С СHowever, the test may be applicable in certain cases at the available user ports. It is not proposed as a general acceptance test which might require special defined access ports and connection arrangements within the equipment. ‚б cмˆ4 PŽТ б Ср TСAPPENDIX II Ср MСб cмˆ4 PŽТ б(to Recommendation G.958) Ср =СУ УDescription of automatic laser shutdown (ALS) capability Ср NСin case of cable breakФ Ф Ср IСб cмˆ4 PŽТ бFIGURE IIЉ1/G.958 = 5,5 cm =,293 б cмˆ4 PŽТ б а H аС СIf a cable break happens at point A, the consecutive loss of signal at RXб cмˆ4 PŽТ бУУ2ФФб cмˆ4 PŽТ б is used to cut TXб cмˆ4 PŽТ бУУ2ФФб cмˆ4 PŽТ б which is the adjacent transmitter in the opposite direction. This in turn leads to a loss of signal in RXб cмˆ4 PŽТ бУУ1ФФб cмˆ4 PŽТ б which switches off TXб cмˆ4 PŽТ бУУ1ФФб cмˆ4 PŽТ б. а H аС СFor test and monitoring purposes it is possible to override the shutdown mechanism by switching on the laser manually. а H аС СWhen the cable has been repaired either an automatic or a manual action according to Figure IIЉ2/G.958, at TXб cмˆ4 PŽТ бУУ1ФФб cмˆ4 PŽТ б or TXб cмˆ4 PŽТ бУУ2ФФб cмˆ4 PŽТ б is necessary to restore correct transmission. а H аС СThe response time of the transmitter/receiver combination, measured from receiver input (point R) to transmitter output (point S) should be less а H аthan 0.85 seconds. This response time of 0.85 seconds refers to the time difference between the moment light enters the receiver at point R and the moment the transmitter starts light emitting at point S in case the transmitter is in the shut down situation. а H аС СР"РManual restartР"Р or Р"РManual restart for testР"Рcan only be activated when the laser is shut down. а H аС СIn case 1+1 protection switching is implemented a working channel receiver should shut down a working channel transmitter. Similarly, a protection channel receiver should shut down a protection channel transmitter.‚б cмˆ4 PŽТ б Ср HС FIGURE IIЉ2/G.958 = 23,5 cm = 919 б cмˆ4 PŽТ б Та ТС€ HСУ УReferenceФ ФЦЦ [1]Тh  ТIEC 825 Standard УУRadiation safety of laser products equipment, classification, requirements and user's guide.ФФЦЦ ‚ аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџH јP Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ б б cмˆ4 PŽТ бвЦ‚HјР!Цв‡аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бIMPORT R:\\ART\\WMF\\ITU.WMF \* mergeformatб cмˆ4 PŽТ бУ У Ф ФаЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHP И XА`ИhР!Р!џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ б б cмˆ4 PŽТ бINTERNATIONAL TELECOMMUNICATION UNIONб cмˆ4 PŽТ бУ У а јА ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџјP И XА`ИhР!Р!џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаˆа HH ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи P Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬа аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHјpи (#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ ЬаТа ТТ№ ТТ№јТб cмˆ4 PŽТ бCCITTб cмˆ4 PŽТ бСHШ AСƒб cмˆ4 PŽТ бG.958УУб cмˆ4 PŽТ бЦЦ аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHјpи А"(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ ЬаТа ТТ№ ТТ№јТ‚б cмˆ4 PŽТ бФ ФФФTHE INTERNATIONALЦЦ Та ТТ№ ТТ№јТTELEGRAPH AND TELEPHONEЦЦ Та ТТ№ ТТ№јТCONSULTATIVE COMMITTEEЦЦ Та ТТ№ ТТ№јТб cмˆ4 PŽТ бЦЦ аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи А"(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬа аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHјpи А"(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ ЬаТа ТТ№ ТТ№јТб cмˆ4 PŽТ бУ УDIGITAL NETWORKS, DIGITAL SECTIONSЦЦ Та ТТ№ ТТ№јТAND DIGITAL LINE SYSTEMSЦЦ Та ТТ№ ТТ№јТб cмˆ4 PŽТ бЦЦ Та ТТ№ ТТ№јТЦЦ Та ТТ№ ТТ№јТDIGITAL LINE SYSTEMS BASED ON THEЦЦ Та ТТ№ ТТ№јТSYNCHRONOUS DIGITAL HIERARCHYЦЦ Та ТТ№ ТТ№јТFOR USE ON OPTICAL FIBRE CABLESЦЦ Та ТТ№ ТТ№јТЦЦ Та ТТ№ ТТ№јТб cмˆ4 PŽТ бЦЦ Та ТТ№ ТТ№јТЦЦ Та ТТ№ ТТ№јТЦЦ Та ТТ№ ТТ№јТб cмˆ4 PŽТ бRecommendation G.958б cмˆ4 PŽТ бЦЦ Та ТТ№ ТТ№јТЦЦ Та ТТ№ ТТ№јТб cмˆ4 PŽТ бФ ФЦЦ Та ТТ№ ТТ№јТб cмˆ4 PŽТ бвЦ‚HјР!Цв‡аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHјpи џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаIMPORT R:\\ART\\WMF\\CCITTRUF.WMF \* mergeformatб cмˆ4 PŽТ бУ УЦЦТа ТТ№ ТТ№јТ аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHјP И XА`ИhР!Р!џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бФ ФGeneva, 1990б cмˆ4 PŽТ бУ УЦЦ а јА ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџјP И XА`ИhР!Р!џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаˆФ Фа HH ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи А"(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬа‚ аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи P Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ б ‚У У Та ТС€ HССр8NСFOREWORDФ ФЦЦ а H№ аС СThe CCITT (the International Telegraph and Telephone Consultative Committee) is the permanent organ of the International Telecommunication Union (ITU). CCITT is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. а H аС СThe Plenary Assembly of CCITT which meets every four years, establishes the topics for study and approves Recommendations prepared by its Study Groups. The approval of Recommendations by the members of CCITT between Plenary Assemblies is covered by the procedure laid down in CCITT Resolution No. 2 (Melbourne, 1988). а H аС СRecommendation G.958 was prepared by Study Group XV and was approved under the Resolution No. 2 procedure on the 14th of December 1990. ‚Ср PС___________________  Та ТС€ HС‚Ср TСб cмˆ4 PŽТ бCCITT NOTEУ Уб cмˆ4 PŽТ бЦЦ б cмˆ4 PŽТ бФ ФС СIn this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication Administration and a recognized private operating agency. ‚Ср UСРMР  ITU  1990 а H а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 microfilm, without permission in writing from the ITU. ‚