ÿWPCL ûÿ2BJ|xÐ ` ÐÐÌÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿH øÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÌÐÐ °°°è ÐÑ Âx„|ü@Ž ÑÐ Å°6Ø'°6Ø'Å Ð4.ÁHÁÓÓÃÃRecommendation I.431ÄÄ Áà$ÁPRIMARY RATE USER©NETWORK INTERFACE © LAYER 1 SPECIFICATIONƒ 1.ÁHÁÃÃIntroductionÄÄ Ð À ÐÁHÁThis Recommendation is concerned with the layer 1 electrical, format and channel usage characteristics of the primary rate user©network interface at the S and T reference points. In this Recommendation, the term "NT" is used to indicate network terminating layer 1 aspects of NT1 and NT2 functional groups, and the term "TE" is used to indicate terminal terminating layer 1 aspects of TE1, TA and NT2 functional groups, unless otherwise indicated. The terminology used in this Recommendation is very specific and not contained in the relevant terminology Recommendations. Therefore, Annex E to Recommendation I.430 provides terms and definitions used in this Recommendation. Interfaces for the 1544 kbit/s primary rate and for the 2048 kbit/s primary rate are described. Ð h ÐIt has been an objective that differences between the interface specifications for the two rates be kept to a minimum. 1.1ÁHÁÃÃScope and field of applicationÄÄ ÁHÁThis specification is applicable to user©network interfaces at 1544 kbit/s and 2048 kbit/s primary rates for ISDN channel arrangements as defined in Recommendation I.412. 2.ÁHÁÃÃType of configurationÄÄ ÁHÁThe type of configuration applies only to the layer 1 characteristics of the interface and does not imply any constraints on modes of operation at higher layers. 2.1ÁHÁÃÃPoint©to©pointÄÄ ÁHÁThe primary rate access will support only the point©to©point configuration. ÁHÁPoint©to©point configuration at layer 1 implies that for each direction only one source (transmitter) and one sink (receiver) are connected to the interface. The maximum reach of the interface in the point©to©point configuration is limited by the specification for the electrical characteristics of transmitted and received pulses and the type of interconnecting cable. Some of these characteristics are defined in Recommendation G.703. 2.2ÁHÁÃÃLocation of interfacesÄÄ ÁHÁThe electrical characteristics for both the 1544 kbit/s case (ÀÀ 4.1) and the 2048 kbit/s case (ÀÀ 5.1) apply at the interfaces Ia and Ib defined in Figure 1/I.431. Note © Ia and Ib are located at the input/output port of the TE/NT. Áà8KÁFIGURE 1/I.431ƒ Áà8RÁƒ Áà8GÁÃÃLocation of interfacesÄă ÁHÁExamples of functional groups corresponding to TE and NT as used here are given in Recommendation I.411, item 4.3. 3.ÁHÁÃÃFunctional characteristicsÄÄ 3.1ÁHÁÃÃSummary of functions (Layer 1)ÄÄ ÃÃNoteÄÄ © This power©feeding©function is optional and, if implemented, uses a separate pair of wires in the interface cable. Áà8JÁFIGURE 2/I.431 ƒ Áà8EÁÃÃFunctional characteristicsÄă ÃÃB ChannelÄÄ ÁHÁThis function provides for the bidirectional transmission of independent B Channel signals each having a bit rate of 64 kbit/s as defined in Recommendation I.412. ÃÃH0 ChannelÄÄ ÁHÁThis function provides for the bidirectional transmission of independent H0 Channel signals each having a bit rate of 384 kbit/s as defined in Recommendation I.412. ÃÃH1 ChannelsÄÄ ÁHÁThis function provides for the bidirectional transmission of anÔ ñ,ÔŒH1 Channel signal having a bit rate of 1536 (H11) or 1920 (H12) bit/s as defined in Recommendation I.412. ÃÃD ChannelÄÄ ÁHÁThis function provides for the bidirectional transmission of one D Channel signal at a bit rate of 64 kbit/s as defined in Recommendation I.412. ÃÃBit timingÄÄ ÁHÁThis function provides bit (signal element) timing to enable the TE or NT to recover information from the aggregate bit stream. ÃÃOctet timingÄÄ ÁHÁThis function provides 8 kHz timing towards TE or NT for the purpose of enabling an octet structure for voice coders and for other timing purposes as required. ÃÃFrame alignmentÄÄ ÁHÁThis function provides information to enable the TE or NT to recover the time©division multiplexed channels. ÃÃPower feedingÄÄ ÁHÁThis function provides for the capability to transfer power across the interface towards the NT1. ÃÃMaintenanceÄÄ ÁHÁThis function provides information concerning operational or failure conditions of the interface. The network reference configuration activities on primary rate subscriber access is given in Recommendation I.604. ÃÃCRC procedureÄÄ ÁHÁThis function provides for the protection against false framing and may provide for error performance monitoring of the interface. 3.2ÁHÁÃÃInterchange circuitsÄÄ ÁHÁTwo interchange circuits, one for each direction, are used for the transmission of digital signals. All the functions listed above, with the possible exception of maintenance, are combined into two composite digital signals, one for each direction of transmission. ÁHÁIf power feeding via the interface is provided, an additional interchange circuit is used for power feeding. ÁHÁThe two wires of the pairs carrying the digital signal may be reversed if symmetrical wiring is provided. 3.3ÁHÁÃÃActivation/deactivationÄÄ ÁHÁThe interfaces for the primary rate user©network interface will be active at all times. No activation/deactivation procedures will be applied at the interface. However, to indicate the layer 1 transport capability to layer 2, the same primitive set is used as defined in Recommendation I.430. This provides for a unique application of the layer 1/layer 2 interface as defined in Recommendations I.420 and I.421 (see ÀÀ 3.4.5). The primitives PH©AR, ÀÀ PH©DR, MPH©DI and MPH©II are not required for this application and, therefore, they are not used in this Recommendation. 3.4ÁHÁÃÃOperational functionsÄÄ ÁHÁIn this paragraph the term network is used to indicate either: ÁHÁÁ  Á©Âà øÂNT1, LT and ET functional groups in case of interface at T reference point;ÆÆ ÁHÁor ÁHÁÁ  Á©Âà øÂrelevant parts of NT2 functional group in case of interface at S reference point.ÆÆ ÁHÁThe term user side is used to indicate terminal terminating layer 1 aspects of TE1, TA and NT2 functional groups. 3.4.1ÁHÁÃÃDefinition of signals at the interfaceÄÄ ÁHÁSignals exchanged between the network and user sides under normal and fault conditions are listed in Table 1/I.431. Further information on these signals is given in ÀÀ 4.7.3 and ÀÀ 5.9.1 Áà8RÁƒ Áà8LÁTABLE 1/I.431ƒ Áà8RÁƒ Áà8=ÁÃÃSignals between the network and user sidesÄă Áà8BÁÃÃunder normal and fault conditionsÄă Áà8RÁƒ Áà80ÁÀ ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ Àƒ Áà80ÁÀ À Name À À List of the signals À Àƒ Áà80ÁÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀƒ Áà80ÁÀ À Normal À À Operational frame with: À Àƒ Áà80ÁÀ À operational À À © active associated CRC À Àƒ Áà80ÁÀ À frame À À © CRC error information (see Recommendation G.704) À Àƒ Áà80ÁÀ À À À © no defect indication À Àƒ Áà80ÁÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀƒ Áà80ÁÀ À À À Operational frame with: À Àƒ Áà80ÁÀ À À À © active associated CRC À Àƒ Áà80ÁÀ À R A I À À © CRC error information (Note) À Àƒ Áà80ÁÀ À À À © with defect indication (see Recommendation G.704)À Àƒ Áà80ÁÀ À À À (2048 kbit/s systems only) À Àƒ Áà80ÁÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀƒ Áà80ÁÀ À LOS À À No received incoming signal (Loss of signal) À Àƒ Áà80ÁÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀƒ Áà80ÁÀ À AIS À À Continuous stream of ONEs (Recommendation G.803) À Àƒ Áà80ÁÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀƒ Áà80ÁÀ À CRC error À À E bit according to Recommendation G.704, À Àƒ Áà80ÁÀ À information À À Table 4b, set to "ZERO" if CRC block received À Àƒ Áà80ÁÀ À À À with error (2048 kbit/s systems only) À Àƒ Áà80ÁÀ ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ Àƒ ÃÃNoteÄÄ © The 1544 kbit/s systems RAI and CRC©derived error performance information cannot be sent simultaneously. Failure conditions may be sectionalized across the interface by obtaining additional information by means that are for further study. 3.4.2ÁHÁÃÃDefinitions of state tables at network and user sidesÄÄ ÁHÁThe user side and network side of the interface have to inform each other on the layer 1 states in relation to the different defects that could be detected. ÁHÁFor that purpose, two state tables are defined, the first one at the user side and the second one at the network side. States at the user side (F states) are defined in ÀÀ 3.4.3 and states at the network side (G states) are defined in ÀÀ 3.4.4. The state tables are defined in ÀÀ 3.4.6. ÁHÁDefect conditions FC1©FC4 that could occur at the network side or between the network side and user side are defined in Figure 3/I.431. These defect conditions directly affect the F and G states. Information on these defect conditions are exchanged between the user and network sides in the form of signals defined in Table 1/I.431. ÃÃNote 1ÄÄ © Only stable states needed for operation and maintenance of user and network side of the interface (system reactions, user and network responsible information) are defined. The transient states relative to the detections of the CRC error information are not taken into account. ÃÃNote 2ÄÄ © The user does not need to know where a failure is located in the network. The user must be informed on the availability and the continuity of the layer 1 service. ÃÃNote 3ÄÄ © The user has all information relative to the CRC associated with each direction of its adjacent CRC section. The supervision of the quality of this section is the user's responsibility. Áà8KÁFIGURE 3/I.431 ƒ Áà8RÁƒ Áà87ÁÃÃLocation of fault conditions (FC) relative to interfaceÄă 3.4.3ÁHÁÃÃLayer 1 states on the user side of the interfaceÄÄ ÃÃF0 STATEÄÄ: Loss of power on the user side: ÁHÁIn general, the TE can neither transmit nor receive signals. ÃÃF1 STATEÄÄ: Operational state: ÁHÁ©Á  Áthe network clock and layer 1 service is available; ÁHÁ©Âà  Âthe user side transmits and receives operational frames with associated CRC and with temporary CRC error information (Note 1);ÆÆ ÁHÁ©Âà  Âthe user side checks the received frames and the associated CRC, and generates towards the network operational frames containing the CRC error information, if a CRC error is detected.ÆÆ ÃÃF2 STATEÄÄ: Fault condition No. 1: ÁHÁ©Á  Áthis fault state corresponds to the fault condition FC1; ÁHÁ©Á  Áthe network clock is available at the user side; ÁHÁ©Âà  Âthe user side receives operational frames with associated CRC and with temporary CRC error information (Note 1);ÆÆ ÁHÁ©Á  Áthe received frames contain RAI; ÁHÁ©Á  Áthe user side transmits operational frames with associated CRC; ÁHÁ©Âà  Âthe user side checks the received frames and the associated CRC and transmits to the network side operational frames containing the CRC error information, if a CRC error is detected.ÆÆ ÃÃF3 STATEÄÄ: Fault condition No. 2: ÁHÁ©Á  Áthis fault state corresponds to the fault condition FC2; ÁHÁ©Á  Áthe network clock is not available at the user side; ÁHÁ©Âà  Âthe user side detects loss of incoming signal (this will involve loss of frame alignment);ÆÆ ÁHÁ©Âà  Âthe user side transmits operational frames with associated CRC and RAI (Note 3).ÆÆ ÃÃF4 STATEÄÄ: Fault condition No. 3: ÁHÁ©Á  Áthis fault state corresponds to fault condition FC3; ÁHÁ©Á  Áthe network clock is not available at the user side; ÁHÁ©Á  Áthe user side detects AIS; ÁHÁ©Âà  Âthe user side transmits towards the network operational frames with associated CRC and RAI (Note 3).ÆÆ ÃÃF5 STATEÄÄ: Fault condition No. 4: ÁHÁ©Á  Áthis fault state corresponds to the fault condition FC4; ÁHÁ©Á  Áthe network clock is available at the user side; ÁHÁ©Âà  Âthe user side receives operational frames with continuous CRC error information (optional) (Note 2);ÆÆ ÁHÁ©Á  Áthe received frames contain RAI; ÁHÁ©Á  Áthe user side transmits operational frames with associated CRC; ÁHÁ©Âà  Âthe user side checks the received frames and the associated CRC which may generate to the network side operational frames containing the CRC error information if a CRC error is detected.ÆÆ ÃÃF6 STATEÄÄ: Power on state: ÁHÁThis is a transient state and the user side may change the state after detection of the signal received. ÃÃNote 1ÄÄ © The interpretation of the CRC error information depends on the option used in the network (see ÀÀ 5.9.2 and Recommendation I.604). ÃÃNote 2ÄÄ © Only in options 2 and 3, as defined in Recommendation I.604, for CRC error information. ÃÃNote 3ÄÄ © The 1544 kbit/s systems RAI and CRC © derived error performance information cannot be sent simultaneously. Failure conditions may be sectionalized across the interface by obtaining additional information by means that are for further study. 3.4.4ÁHÁÃÃLayer 1 states at the network side of the interfaceÄÄ ÃÃGO STATEÄÄ: Loss of power in the NT1: ÁHÁIn general, the NT1 can neither transmit nor receive any signal. ÃÃG1 STATEÄÄ: Operational state: ÁHÁ©Á  Áthe network clock and layer 1 service is available; ÁHÁ©Âà  Âthe network side transmits and receives operational frames with associated CRC and temporary CRC error information;ÆÆ ÁHÁ©Âà  Âthe network side checks the received frames and the associated CRC and generates towards the user side the CRC error information if a CRC error is detected.ÆÆ ÃÃG2 STATEÄÄ: Fault condition No. 1: ÁHÁ©Á  Áthis fault state corresponds to the fault condition FC1; ÁHÁ©Âà  Âthe network clock is provided to the user side;ÆÆ ÁHÁ©Âà  Âthe network side receives operational frames with associated CRC;ÆÆ ÁHÁ©Âà  Âthe network side transmits operational frames with associated CRC and RAI. The operational frames may contain CRC error information (Note 1).ÆÆ ÃÃG3 STATEÄÄ: Fault condition No. 2: ÁHÁ©Á  Áthis fault state corresponds to the fault condition FC2; ÁHÁ©Á  Áthe network clock is not provided to the user side; ÁHÁ©Âà  Âthe network side transmits operational frames with associated CRC;ÆÆ ÁHÁ©Âà  Âthe network side receives operational frames with associated CRC and RAI (Note 3).ÆÆ ÃÃG4 STATEÄÄ: Fault condition No. 3: ÁHÁ©Á  Áthis fault state corresponds to the fault condition FC3; ÁHÁ©Á  Áthe network clock is not provided to the user side; ÁHÁ©Á  Áthe network side transmits AIS; ÁHÁ©Âà  Âthe network side receives operational frames with associated CRC and RAI (Note 3).ÆÆ ÃÃG5 STATEÄÄ: Fault condition No. 4: ÁHÁ©Á  Áthis fault states corresponds to the fault condition FC4; ÁHÁ©Á  Áthe network clock is provided to the user side; ÁHÁ©Âà  Âthe network side detects loss of incoming signal or loss of frame alignment;ÆÆ ÁHÁ©Âà  Âthe network side transmits operational frames with associated CRC and RAI and continuous CRC error information (Notes 2 and 3).ÆÆ ÃÃG6 STATEÄÄ: Power on state: ÁHÁThis is a transient state and the network side may change the state after detection of the signal received. ÃÃNote 1ÄÄ © The interpretation of the CRC error information depends on the option used in the network (see ÀÀ 5.9.2 and Recommendation I.604). ÃÃNote 2ÄÄ © Only in options 2 and 3, as defined in Recommendation I.604 for CRC error information. ÃÃNote 3ÄÄ © In 1544 kbit/s systems RAI and CRC © derived error performance information cannot be sent simultaneously. Failure conditions may be sectionalized across the interface by obtaining additional information by means that are for further study. 3.4.5ÁHÁÃÃDefinition of primitiveÄÄ ÁHÁThe following primitives should be used between layers 1 and 2 (PH) or between layer 1 and the management entity (MPH). ÁHÁPH AI © PH Activate indication ÁHÁPH DI © PH Deactivate Indication ÁHÁMPH AI © MPH Activate Indication (is used as error recovery and                       initialization information) ÁHÁMPH EIn © MPH Error Indication with Parameter ÁHÁn © Parameter which defines the failure condition relevant to the reported error 3.4.6ÁHÁÃÃState tablesÄÄ ÁHÁ Operational functions are defined in Table 2/I.431 for the layer 1 states at the user side of the interface and in Table 3/I.431 for the network side. The exact reaction in case of double faults may depend on the type of double fault condition and the sequence in which they occur. Áà8LÁTABLE 2/I.431ƒ Áà8RÁƒ Áà8@ÁÃÃPrimary rate layer 1 state matrix atÄă Áà8EÁÃÃuser side of the interfaceÄă PA©AI = PH Activate Indication PH©DI = PH Deactivate Indication MPH©EIn = MPH error Indication with parameter n (n = 0 to 4) ÃÃNote 1ÄÄ © These events cover different network options. The network options 2 and 3 (see Recommendation I.604) of the 2048 kbit/s system (which include CRC processing in the digital transmission link) provide CRC©error information which allows the user side equipment to localize a fault indicated by means of RAI to either: ÁHÁi)Âh   Ânetwork side (FC1), if frames without continuous CRC©error reports are received; orÆÆ ÁHÁii)Âð   Âthe user side (FC4), if frames with continuous CRC©error reports are received.ÆÆ ÁHÁIf network options other than 2 and 3 of the 2048 kbit/s system apply, the faults FC1 and FC4 are indicated identically at the interface, therefore, the signal "RAI with continuous CRC error report" does not occur. ÃÃNote 2ÄÄ © These states cover two user options: ÁHÁi)Âh   ÂIf a TE adopting the option to distinguish between F2 and F5 (given by options 2 and 3 of 2048 kbit/s interfaces only) is used, but the network does not provide the distinction (see Note 1), then signal "RAI with continuous CRC error report" will not occur and the TE always enters state F2 on receipt of RAI;ÆÆ ÁHÁii)Âð   ÂThe user option not processing CRC©error information when accompanied with RAI, even if provided, merges states F2 and F5.ÆÆ Áà8LÁTABLE 3/I.431ƒ Áà8RÁƒ Áà81ÁÃÃPrimary rate layer 1 state matrix at network side of the interfaceÄă PH©AI = PH Activate Indication PH©DI = PH Deactivate Indication MPH©EIn = MPH Error Indication with parameter n (n = Q to 4) ÃÃNote 1ÄÄ © In the case of no CRC processing in the digital link, the state G5 is identical to state G2. ÃÃNote 2ÄÄ © In options 2 and 3 of the 2048 kbit/s systems, the RAI signal must contain CRC error information of the section between TE and NT which can be used by the user to localize faults FC1 and FC4. In option 1 the faults FC1 and FC4 are indicated identical at the interface (see ÀÀ 5.9). ÃÃ*ÄÄ  The issue of this primitive depends on the capability of the digital    transmission system and the option used in the network. 4.ÁHÁÃÃInterface at 1544 kbit/sÄÄ 4.1ÁHÁÃÃElectrical characteristicsÄÄ 4.1.1ÁHÁÃÃBit rateÄÄ ÁHÁThe signal shall have a bit rate of 1544 kbit/s ÀÀ 50 parts per million (ppm). 4.1.2ÁHÁÃÃInterchange circuit mediumÄÄ ÁHÁOne symmetric metallic pair shall be used for each direction of transmission. 4.1.3ÁHÁÃÃCodeÄÄ ÁHÁThe B8ZS code is recommended (see Note 1 under Table 4/I.431 for definition of B8ZS code). 4.1.4ÁHÁÃÃSpecifications at the output portsÄÄ 4.1.4.1Á  ÁTest load ÁHÁTest load impedance shall be 100 ohms, resistive. 4.1.4.2Á  ÁPulse mask ÁHÁAn isolated pulse measured at interfaces Ia or Ib defined in Figure 1/I.431 shall have an amplitude between 2.4 and 3.6 Volts measured at the centre of the pulse. ÁHÁA possible normalized pulse mask is shown in Figure I.1/I.431 (Appendix 1). This pulse mask is for further study. ÁHÁAn isolated pulse shall satisfy the requirements set out in Table 4/I.431. Áà8LÁTABLE 4/I.431ƒ Áà8RÁƒ Áà8BÁÃÃDigital interface at 1544 kbit/sÄă ÃÃNote 1ÄÄ © B8ZS is a modified AMI code in which eight consecutive zeros are replaced with 000 + © 0 © + if the preceding pulse was positive (+) : 000 © + 0 + © if the preceding pulse was negative (©). ÃÃNote 2ÄÄ © The signal level is the power level measured in a 3 kHz bandwidth at the output port for an all 1s pattern transmitted. 4.1.4.3Á  ÁVoltage of zero ÁHÁThe voltage within a time slot containing a zero (space) shall be no greater than either the value produced in that time slot by other pulses (marks) within the mask of Figure I©1/I.431 or ÀÀ 5% of the zero©to©peak pulse (mark) amplitude, whichever is greater in magnitude. 4.1.5ÁHÁÃÃSpecifications at the input portsÄÄ ÁHÁThe digital signal presented at the input port shall be as defined above but modified by the characteristic of the interconnecting pair. The attenuation of this pair shall be assumed to follow a ÀÀf law and the loss at a frequency of 772 kHz shall be in the range 0 to 6 dB. 4.2ÁHÁÃÃFrame structureÄÄ 4.2.1ÁHÁThe frame structure is based on Recommendation G.704, ÀÀÀÀ 3.1.1 and 3.1.2 and is shown in Figure 4/I.431. Áà8KÁFIGURE 4/I.431ƒ Áà8RÁƒ Áà8>ÁÃÃFrame structure of 1544 kbit/s interfaceÄă 4.2.2ÁHÁEach frame is 193 bits long and consists of an F©bit followed by 24 consecutive time slots, numbered 1 to 24. 4.2.3ÁHÁEach time slot consists of eight consecutive bits, numbered 1 to 8. 4.2.4ÁHÁThe frame repetition rate is 8 000 frames/s. 4.2.5ÁHÁThe multi©frame structure is shown in Table 5/I.431. Each multi©frame is 24 frames long and is defined by the multi©frame alignment signal (FAS) which is formed by every fourth F©bit and has the binary pattern ( .... 001011...) 4.2.6ÁHÁThe bits eÃÃ1ÄÄ to eÃÃ6ÄÄ in Table 5/I.431 are used for error checking, as described in ÀÀ 2.1.3.1.2 of Recommendation G.704. A valid error check by the receiver is an indication of transmission quality and of the absence of false frame alignment (see ÀÀ 4.6.3 of this Recommendation). Áà8LÁTABLE 5/I.431ƒ Áà8RÁƒ Áà8HÁÃÃMulti©frame structureÄă ÃÃNote 1ÄÄ © With the exception of ÀÀ 4.7.3 the use of the m bit/s is for further study (for example, for maintenance and operational information). 4.3ÁHÁÃÃTiming considerationsÄÄ ÁHÁThis paragraph describes the hierarchical synchronization method selected for synchronizing ISDNs. It is based upon consideration of satisfactory customer service, ease of maintenance, administration and minimizing cost. ÁHÁThe NT derives its timing from the network clock. The TE synchronizes its timing (bit, octet, framing) from the signal received from the NT and synchronizes accordingly its transmitted signal. 4.4ÁHÁÃÃTime slot assignmentÄÄ 4.4.1ÁHÁÃÃD ChannelÄÄ ÁHÁTime slot 24 is assigned to the D Channel when this channel is present. 4.4.2ÁHÁÃÃB channel and H channelsÄÄ ÁHÁA channel occupies an integer number of time slots and the same time slot positions in every frame. A B Channel may be assigned any time slot in the frame, an H0 Channel may be assigned any six slots in the frame, in numerical order (not necessarily consecutive), and an H11 Channel may be assigned slots 1 to 24 in a frame. The assignment may vary on a call by call basis (see Note). Mechanisms for the assignment of these slots for a call are specified in Recommendation I.451. ÃÃNoteÄÄ © For an interim period, a fixed time slot allocation to form channels may be required. An example of a fixed assignment of slots for the case where only H0 channels are present at the interface is given in Annex A. 4.5ÁHÁÃÃJitterÄÄ 4.5.1ÁHÁÃÃTiming jitterÄÄ ÁHÁTiming jitter is specified as follows. 4.5.1.1Á  ÁTolerable jitter at TE input ÁHÁA TE shall tolerate a sinusoidal input jitter according to the amplitude©frequency characteristic of Figure 5/I.431 without producing bit errors or losing frame alignment. A1 : 5.0  UI A2 : 0.1 UI f1 : 120 Hz f2 : 6 kHz UI : Unit interval (648 ns) Áà8RÁƒ Áà8KÁFIGURE 5/I.431 ƒ Áà8RÁƒ Áà8>ÁÃÃTolerable TE input jitter characteristicÄă 4.5.1.2Á  ÁTE output jitter ÁHÁWith no jitter on the TE input signal that provides timing, jitter at the TE output shall not exceed the following two limitations simultaneously: ÁHÁi)Á   ÁBand 1 (10 Hz © 40 kHz) : 0.5 UI (Unit Interval) peak©to©peak ÁHÁii)Á   ÁBand 2 (8 kHz © 40 kHz) : 0.07 UI peak©to©peak 4.5.2ÁHÁÃÃWanderÄÄ ÁHÁWander is specified for frequencies below 10 Hz. 4.5.2.1Á  ÁSignal from the network side ÁHÁWander shall not exceed 5 UI peak©to©peak in any 15 minute interval and shall not exceed 28 UI peak©to©peak within a period of 24 hours. 4.5.2.2Á  ÁSignal from the user side ÁHÁWander shall not exceed 5 UI peak©to©peak in any 15 minute interval and shall not exceed 28 UI peak©to©peak within a period of 24 hours. 4.6ÁHÁÃÃInterface proceduresÄÄ 4.6.1ÁHÁÃÃCodes for idle channels and idle slotsÄÄ ÁHÁThe pattern including at least three binary ONEs in an octet must be transmitted on every time slot that is not assigned to a channel (e.g. time slots awaiting channel assignment on a per©call basis, residual slots on an interface that is not fully provisioned, etc.), and on every time slot of a channel that is not allocated to a call in both directions. 4.6.2ÁHÁÃÃInterframe (layer 2) timefillÄÄ ÁHÁContiguous HDLC flags shall be transmitted on the D Channel when its layer 2 has no frames to send. 4.6.3ÁHÁÃÃFrame alignment and CRC©6 procedureÄÄ ÁHÁThe frame alignment and CRC©6 procedures shall be in accordance with Recommendation G.706 ÀÀ 2. 4.7ÁHÁÃÃMaintenanceÄÄ 4.7.1ÁHÁÃÃGeneral introductionÄÄ ÁHÁRecommendation I.604 specifies an overall approach to be employed in maintaining ISDN primary rate access. However, since the required maintenance functions may influence the design of terminating pieces of equipment, a brief description of primary rate access maintenance is presented in this Recommendation. 4.7.2.Á  ÁÃÃMaintenance functionsÄÄ ÁHÁThe interface divides maintenance responsibility between network and user sides. ÁHÁSpecified maintenance functions are as follows: ÁHÁa)Âh   ÂSupervision of layer 1 capability and reporting across the interface, which includes, on the user side, reporting loss of incoming signal or loss of frame alignment from the network side.ÆÆ ÁHÁÂX  ÂOn the network side, reporting loss of layer 1 capability and the incoming signal or frame alignment from the user side, are included.ÆÆ ÁHÁb)Âh   ÂCRC performance monitoring and reporting across the interface. (This function is specified in ÀÀ 4.7.4.)ÆÆ ÁHÁc)Âh   ÂOther maintenance functions are for further study.ÆÆ 4.7.3ÁHÁÃÃDefinition of maintenance signals at the interfaceÄÄ ÁHÁThe RAI (Remote Alarm Indication) signal indicates loss of layer 1 capability at the user©network interface. RAI propagates towards the network if layer 1 capability is lost in the direction of the user, and RAI propagates toward the user if layer 1 capability is lost in the direction of the network. RAI is coded as continuously repeated 16©bit sequences of eight binary ONEs and eight binary ZEROs (1111111100000000) in the m bit. (Note © HDLC flag patterns (01111110) are transmitted in the m bits when no information signal is to be sent.) ÁHÁThe AIS (Alarm Indication Signal) is used to indicate loss of layer 1 capability in the ET©to©TE direction on the network side of the user©network interface. A characteristic of AIS is that its presence indicates that the clock provided to the TE may not be the network clock. AIS is coded as a binary all ONEs, 1544 kbit/s bit stream. ÁHÁIn leased line circuit applications with no D Channel, some channel© associated layer maintenance messages may need to be transferred across the interface. These maintenance messages would be transported in the m bit. Further characteristics of these messages are for further study. 4.7.4ÁHÁÃÃCRC©6 in©service performance monitoring and reportingÄÄ ÁHÁMessages in the m bit that exercise CRC©6 performance monitoring capabilities can be used to sectionalize troubles in the primary rate access. This sectionalization could be accomplished from either the NT or the TE. Characteristics of these maintenance messages are for further study. 5.ÁHÁÃÃInterface at 2048 kbit/sÄÄ 5.1ÁHÁÃÃElectrical characteristicsÄÄ ÁHÁThis interface should conform to Recommendation G.703, ÀÀ 6, which recommends the basic electrical characteristics. ÃÃNoteÄÄ © The use of the unbalanced 75 ohm (coaxial) interface is required by some administrations in the short term. However, the balanced 120 ohm (symmetric pair) interface is preferred for the ISDN primary rate application. 5.2ÁHÁÃÃFrame structureÄÄ 5.2.1ÁHÁÃÃNumber of bits per time slotÄÄ ÁHÁEight, numbered from 1 to 8. 5.2.2ÁHÁÃÃNumber of time slots per frameÄÄ ÁHÁThirty©two, numbered from 0 to 31. The number of bits per frame is 256 and the frame repetition rate is 8 000 frames/s. 5.2.3ÁHÁÃÃAssignment of bits in time slot 0ÄÄ ÁHÁThe bits of time slot 0 are in accordance with Recommendation G.704, ÀÀ 2.3.2. The E bits are assigned to the CRC error information procedures. ÁHÁSa bits with bit position 4 and 8 are reserved for international standardization and shall be ignored by the TE for the time being. Sa bits with position 5,6,7: are reserved for national use. The terminals not making use of these bits shall ignore any received pattern. 5.2.4ÁHÁÃÃTime slot assignmentÄÄ 5.2.4.1Á  ÁFrame alignment signal ÁHÁTime slot 0 provides for frame alignment in accordance with ÀÀ 5.2.3. 5.2.4.2Á  ÁD Channel ÁHÁTime slot 16 is assigned to the D Channel when this channel is present. The assignment of time slot 16 when not used for a D Channel is for further study. 5.2.4.3Á  ÁB Channel and H Channels ÁHÁA channel occupies an integer number of time slots and the same time slot positions in every frame. ÁHÁA B Channel may be assigned any time slot in the frame and an H0 Channel may be assigned any six slots, in numerical order, not necessarily consecutive (Note 1). ÁHÁThe assignment may vary on a call by call basis (Note 2). Mechanisms for the assignment of these slots for a call are specified in Recommendation I.451. ÁHÁAn H12 Channel shall be assigned time slots 1 to 15 and 17 to 31 in a frame and an H11 Channel may be assigned time slots as in the example given in Annex B. ÃÃNote 1ÄÄ © In any case time slot 16 should be kept free for D Channel utilization. ÃÃNote 2ÄÄ © For an interim period, a fixed time slot allocation to form channels may be required. Examples of a fixed assignment of slots for the case where only H0 Channels are present at the interface are given in Annex A. 5.2.4.4Á  ÁÃÃBit sequence independentÄÄ ÁHÁTime slots 1 to 31 provide bit sequence independent transmission. 5.3ÁHÁÃÃTiming considerationsÄÄ ÁHÁThe NT derives its timing clock from the network clock. The TE synchronizes its timing (bit, octet, framing) from the signal received from the NT and synchronizes accordingly the transmitted signal. ÁHÁIn an unsynchronized condition (e.g. when the access that normally provides network timing is unavailable) the frequency deviation of the free© running clock shall not exceed ÀÀ 50 ppm. 5.4 ÁHÁÃÃJitterÄÄ 5.4.1ÁHÁÃÃGeneral considerationsÄÄ ÁHÁThe jitter specifications take into account subscriber configurations with only one access and configurations with multiple accesses. ÁHÁIn the case of one access only, this may be to a network with transmission systems of either high Q or low Q clock recovery circuits. ÁHÁIn the case of multiple accesses, all access transmission systems may be of the same kind (either low Q or high Q clock recovery circuits) or they may be of different kinds (some with high Q and some with low Q clock recovery circuits). ÁHÁExamples of single and multiple accesses are given in Figure 6/I.431. ÁHÁThe reference signal for the jitter measurement is derived from the network clock. The nominal value for 1 UI is 488 ns. Áà8KÁFIGURE 6/I.431ƒ Áà8RÁƒ Áà8>ÁÃÃExamples of single and multiple accessesÄă 5.4.2ÁHÁÃÃMinimum tolerance to jitter and wander at TE inputsÄÄ ÁHÁThe 2048 kbit/s inputs of a TE shall tolerate sinusoidal input jitter/wander in accordance with Figure 7/I.431 without producing bit errors or losing frame alignment. À ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ À À À AÃÃ0ÄÄ À À AÃÃ1ÄÄ À À AÃÃ2ÄÄ À À fÃÃ0ÄÄ À À f1 À À f2 À À f3 À À f4 À À ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ À À À Note 1 À À Note 2 À À À À À À À À À À À À À À À À 20.5 UI À À 1.0 UI À À 0.2 UI À À12x10Ãé6ÄÄ HzÀ À 20 Hz À À3.6 kHzÀ À18 kHz À À100 kHz À À À ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ À ÃÃNote 1ÄÄ © Jitter/wander (MRTIE © Maximum Relative Time Interval Error) as defined in Recommendation G.812. ÃÃNote 2ÄÄ © TEs for multipurpose application (i.e., also to private circuit run by public telecommunications operator) a jitter tolerance of 1.5 (with corresponding f2 at 2.4 kHz) may be required. Áà8KÁFIGURE 7/I.431ƒ Áà8RÁƒ Áà8;ÁÃÃMinimum Tolerable jitter and wander at TE inputÄă 5.4.3ÁHÁÃÃTE and NT2 output jitterÄÄ ÁHÁTwo cases must be considered: 5.4.3.1Á  ÁTE and NT2 with only one user©network interface ÁHÁa)Âh   ÂWith no jitter at the input supplying timing or in the running mode, the TE output jitter shall be in accordance with the table below:ÆÆ Áà85ÁÀ ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ Àƒ Áà85ÁÀ À Measurement Filter bandwidth: À À Output jitter: À Àƒ Áà85ÁÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ À Àƒ Áà85ÁÀ À Lower Cutoff À À Upper Cutoff À À UI Peak©to©peak À Àƒ Áà85ÁÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀƒ Áà85ÁÀ À 20 Hz À À 100 kHz À À ÀÀ 0.125 UI À Àƒ Áà85ÁÀ À 700 Hz À À 100 kHz À À ÀÀ 0.02 UI À Àƒ Áà85ÁÀ ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ Àƒ ÁHÁb)Âh   ÂWith jitter present at the input supplying timing, the output jitter is the sum of the intrinsic jitter of the TE plus the input jitter multiplied with the jitter transfer characteristics.ÆÆ ÂHHÂÂX  ÂThe jitter transfer characteristics shall conform to Figure 8/I.431:ÆÆ Ð ` Ð Áà"ÁÀ ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ Àƒ Áà"ÁÀ À y À À x À À fa À À fb À À fc À À fd À Àƒ Áà"ÁÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀƒ Áà"ÁÀ À©19.5 dB À À 0.5 dB À À 10 Hz À À 40 Hz À À 400 Hz À À 100 kHz À Àƒ Áà"ÁÀ ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ Àƒ ÁàAÁƒ Áà:ÁFIGURE 8/I.431ƒ ÁàAÁƒ Áà2ÁÃÃJitter transfer characteristicsÄă Ð H Ð5.4.3.2Á  ÁTE with more than one user©network interface to the same network. ÁHÁa)Âh   ÂWith no jitter at the input (or inputs) supplying timing or in the free running mode see ÀÀ 5.4.3.1 a).ÆÆ ÁHÁb)Âh   ÂIn the multi©access case the output jitter depends on:ÆÆ ÁHÁÁ  Á©Âà øÂthe input jitter of each access;ÆÆ ÂHHÂÆÆ Ð ` ÐÁHÁÁ  Á©Âà øÂthe transfer characteristic;ÆÆ ÂHHÂÆÆ ÁHÁÁ  Á©Âà øÂthe timing extraction and distribution concept;ÆÆ ÂHHÂÆÆ Ð ° ÐÁHÁÁ  Á©Âà øÂthe future growth of the TE. Since the timing extraction and distribution concept of the TE is out of the scope of this Recommendation the output jitter at each individual access can be controlled only by the definition of the appropriate jitter transfer characteristic in the TE.ÆÆ ÁHÁIn order to restrict the output jitter to tolerable values and to simplify testing, the jitter transfer characteristic between any receiver and its associated transmitter shall be tested to the transfer characteristic given in Figure 8/I.431 and the following parameters: ÁàX+ÁÀ ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ Àƒ ÁàX+ÁÀ À y À À x À À fa À À fb À À fc À À fd À Àƒ ÁàX+ÁÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀƒ ÁàX-ÁÀ À ©19.8 dB À À 0.2 dB À À not to be À À 0.1 Hz À À 1 Hz À À 100 kHz À Àƒ ÁàX+ÁÀ À À À À À defined À À À À À À À Àƒ ÁàX+ÁÀ À À À À À À À À À À À À Àƒ ÁàX+ÁÀ ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ Àƒ 5.5ÁHÁÃÃTolerable longitudinal voltageÄÄ ÁHÁMinimum tolerance to longitudinal voltage at input ports. Ð H ÐÁHÁThe receiver shall operate without errors with any valid input signal in the presence of a longitudinal voltage VL. ÁHÁVL = 2 Vrms over frequency range 10 Hz to 30 MHz. ÁHÁThe test configuration is given in Figure 9/I.431. ÃÃNoteÄÄ © The inherent longitudinal conversion loss of the T©balancing network should be 20 dB better than required at the interface under test (see Recommendation 0.121). ÁàHNÁƒ ÁàHFÁFIGURE 9/I.431 ƒ ÁàHNÁƒ ÁàH:ÁÃÃTest of tolerance to longitudinal voltageÄă 5.6ÁHÁÃÃOutput signal balanceÄÄ ÁHÁOutput signal balance, which is measured in accordance with Recommendation 0.121, ÀÀ 2.7, shall meet the following requirements: ÁHÁa)Á   Áf = 1 MHz : ÀÀ 40 dB ÁHÁb)Âh   Â1 MHz < f ÀÀ 30 MHz: minimum value decreasing from 40 dB at 20 dB/decade.ÆÆ 5.7ÁHÁÃÃImpedance towards groundÄÄ ÁHÁThe impedance towards ground of both the receiver input and the transmitter output shall meet the following requirements: ÁHÁ10 Hz < f ÀÀ 1 MHz: > 1 000 Ohm ÁHÁThis requirement is met if the test according to Figure 10/I.431 results in a voltage VÃÃtestÄÄ ÀÀ 20 mVrms. ÁàHGÁFIGURE 10/I.431ƒ ÁàHNÁƒ ÁàH:ÁÃÃTest of minimum impedance towards groundÄă 5.8ÁHÁÃÃInterface proceduresÄÄ 5.8.1ÁHÁÃÃCodes for idle channels and idle slotsÄÄ ÁHÁThe pattern including at least three binary ONEs in an octet must be transmitted on every time slot that is not assigned to a channel (e.g. time slots awaiting channel assignment on a per©call basis, residual slots on an interface that is not fully provisioned, etc.), and on every time slot of a channel that is not allocated to a call in both directions. 5.8.2ÁHÁÃÃInterframe (layer 2) time fillÄÄ ÁHÁContiguous HDLC flags will be transmitted on the D Channel when its layer 2 has no frames to send. 5.8.3ÁHÁÃÃFrame alignment and CRC©4 proceduresÄÄ ÁHÁThe frame alignment and CRC procedures shall be in accordance with Recommendation G.706, ÀÀ 4. 5.9ÁHÁÃÃMaintenance at the interfaceÄÄ ÁHÁThe network reference configuration for the maintenance activities on primary rate subscriber access is given in Recommendation I.604. ÁHÁThe associated maintenance procedure, which is described there, needs a continuous supervision procedure on layer 1 for the automatic fault detection, automatic failure confirmation and information. ÃÃNoteÄÄ © The terms anomaly, defect, fault, and failure are defined in Recommendation M.20. 5.9.1ÁHÁÃÃDefinitions of maintenance signalsÄÄ ÁHÁThe RAI (Remote Alarm Indication) signal indicates loss of layer 1 capability at the user©network interface. RAI propagates towards the network if layer 1 capability is lost in the direction of the user, and RAI propagates toward the user if layer 1 capability is lost in the direction of the network. RAI is coded in bit A, i.e. bit 3 of time slot 0 of the operational frame which does not contain the frame alignment signal (see Table 4b/G.704). RAI © A©bit set to 1 No RAI © A©bit set to 0 ÁHÁThe AIS (Alarm Indication Signal) is used to indicate loss of layer 1 capability in the ET©to©TE direction on the network side of the user©network interface. A characteristic of AIS is that its presence indicates that the clock provided to the TE may not be the network clock. AIS is coded as a binary all ONEs, 2048 kbit/s bit stream. ÁHÁThe CRC error information: E bit in time slot 0 of operational frames not containing the frame alignment signal. 5.9.2ÁHÁÃÃUse of CRC procedureÄÄ 5.9.2.1Á  ÁIntroduction ÁHÁAt the user©network interface the CRC procedure according to Recommendations G.704 and G.706 is applied to gain security in frame alignment and detect block errors. The CRC error information uses the E bits as defined in Table 4b of Recommendation G.704, the coding is E = "0" for block with failure and E = "1" for block without failure. With respect to CRC error information to the other side of the interface and processing of this information two different options exist, the one has CRC processing in the transmission link and the other not. ÁHÁThe use of CRC procedure at the user©network interface involves: ÁHÁi)Âh   Âthat the user side shall generate towards the interface a 2048 kbit/s frame with associated CRC procedure;ÆÆ ÁHÁii)Âð   Âthat the network side shall generate towards the interface a 2048 kbit/s frame with associated CRC procedure;ÆÆ Ð ð ÐÂHHÂÂX  ÂÁ€ HÁÁ€ÁÁHÁiii)Á øÁthat the user side shall monitor the CRC procedure associated to the received frames (CRC codes calculation and comparison with received CRC codes);ÆÆ ÁHÁiv)Âð   Âthat the user side shall detect the CRC blocks received with error;ÆÆ ÁHÁv)Âh   Âthat the user side shall generate the CRC error information according with the CRC procedure;ÆÆ ÁHÁvi)Âð   Âthat the network side shall monitor the CRC procedure associated to the received frames;ÆÆ ÂHHÂÂX  ÂÁ€ HÁÁ€ÁÁHÁvii)Á øÁthat the network side shall detect the CRC blocks received with error;ÆÆ ÂHHÂÂX  ÂÁ€ HÁÁ€ÁÁHÁviii)Á øÁthat the network side shall generate the CRC error information according with the CRC procedure;ÆÆ ÁHÁix)Âð   Âthat the network side shall detect the CRC error information and to process all the received information according with Recommendation I.604.ÆÆ ÂHHÂÁ€Á5.9.2.2Á  ÁLocalization of the CRC functions in the subscriber access from the user point of view.ÆÆ 5.9.2.2.1  No CRC processing in the transmission link ÁHÁFigure 11/I.431 gives the locations of the CRC function processes in a subscriber access without CRC processing in the transmission link. LEGEND: G = CRC generator L = Local "CRC error" information M = CRC monitor R = Remote "CRC error" information © = Mandatory .... = Optional Áà8LÁFIGURE 11/I.431ƒ Áà8SÁƒ Áà83ÁÃÃLocalization of CRC processing functions for a subscriber accessÄă Áà8:ÁÃÃwhen the transmission link does not process the CRCÄă 5.9.2.2.2 CRC processing in the digital transmission link ÁHÁFigure 12/I.431 gives the locations of CRC function processes in a subscriber access with CRC processing in the NT. LEGEND: G = CRC generator L = Local "CRC error" information M = CRC monitor R = Remote "CRC error" information © = Mandatory .... = Optional ÃÃNoteÄÄ © The processing of remote CRC error information provides enhanced defect localization from the user point of view. Áà8LÁFIGURE 12/I.431ƒ Áà8SÁƒ Áà84ÁÃÃLocalization of CRC processing function for a subscriber accessÄăÔ ñ,ÔŒÁà89ÁÃÃwith CRC processing in the digital transmission linkÄă 5.9.3ÁHÁÃÃMaintenance FunctionsÄÄ 5.9.3.1Á  ÁGeneral requirements ÁHÁThe equipments located on the user side and on the network side of the interface shall: ÁHÁ©Á  Ádetect the anomalies; ÁHÁ©Á  Ádetect the defects; ÁHÁ©Âà  Âtake actions for reporting the detected anomalies and defects (defect indication signals AIS, RAI,....);ÆÆ ÁHÁ©Á  Ádetect the received defect indication signals. 5.9.3.2Á  ÁMaintenance functions on the user side 5.9.3.2.1 Anomalies and defect detection ÁHÁThe user side shall detect the following defects or anomalies: ÁHÁ©Á  Áloss of power on the user side; ÁHÁ©Á  Áloss of incoming signal at interface (see Note); ÁHÁ©Á  Áloss of frame alignment (see Recommendation G.706); ÁHÁ©Á  ÁCRC error. ÃÃNoteÄÄ © The detection of this defect is required only when it has not the effect of a loss of frame alignment indication. 5.9.3.2.2 Detection of defect indication signals ÁHÁThe following defect indications received at interface shall be detected by the user side: ÁHÁ©Á  Áremote alarm indication (RAI) (Note); ÁHÁ©Á  Áalarm indication signal (AIS). ÃÃNoteÄÄ © The RAI signal is used to indicate loss of layer 1 capability. It may be used to indicate: ÁHÁ©Á  Áloss of signal or loss of framing; ÁHÁ©Á  Áexcessive CRC errors, (optional); ÁHÁ©Á  Áloopbacks applied in the network. ÁHÁThe conditions of excessive CRC errors are outside the scope of this Recommendation. 5.9.3.2.3 Consequent actions: ÁHÁTable 6/I.431 gives the actions that the user side (TE function) has to take after the detection of a defect or of a defect indication signal. ÃÃNote 1ÄÄ © When the defect conditions have disappeared or when the defect indication signals are not received any more, the defect indications AIS and RAI must disappear as soon as possible. ÃÃNote 2ÄÄ © The following points are required to ensure that an equipment is not removed from service due to short breaks in transmission: ÁHÁi)Âh   ÂThe persistence of an RAI or of an AIS shall be verified for at least 100 ms before action is taken;ÆÆ ÁHÁii)Âð   ÂWhen an RAI or an AIS disappears, action shall be taken immediately.ÆÆ Áà8MÁTABLE 6/I.431ƒ Áà8SÁƒ Áà8:ÁÃÃDefect conditions and indication signals of defectÄă Áà8;ÁÃÃdetected by the user side and consequent actionsÄă Áà8;ÁÀ ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ Àƒ Áà8;ÁÀ À Defect À À Consequent actions À Àƒ Áà8;ÁÀ À conditions and ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀƒ Áà8;ÁÀ À Defect À À Defect indications À Àƒ Áà8;ÁÀ À indication À À at the interface À Àƒ Áà8;ÁÀ À signals ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀƒ Áà8;ÁÀ À detected by À À Generation À ÀGeneration of À Àƒ Áà8;ÁÀ À the user side À À of RAI À ÀCRC error infoÀ Àƒ Áà8;ÁÀ À À À À À(see Note 4) À Àƒ Áà8;ÁÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀƒ Áà8;ÁÀ À Loss of power À ÀNot applicableÀ ÀNot applicableÀ Àƒ Áà8;ÁÀ À on user side À À À À À Àƒ Áà8;ÁÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀƒ Áà8;ÁÀ À Loss of signal À À Yes À À Yes À Àƒ Áà8;ÁÀ À À À À À (see Note 1) À Àƒ Áà8;ÁÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀƒ Áà8;ÁÀ À Loss of frame À À Yes À À No À Àƒ Áà8;ÁÀ À alignment À À À À (see Note 2) À Àƒ Áà8;ÁÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀƒ Áà8;ÁÀ À Reception of RAIÀ À No À À No À Àƒ Áà8;ÁÀ À À À À À À Àƒ Áà8;ÁÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀƒ Áà8;ÁÀ À Reception of AISÀ À Yes À À No À Àƒ Áà8;ÁÀ À À À À À (see Note 3) À Àƒ Áà8;ÁÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀƒ Áà8;ÁÀ À Detection by NT2À À No À À Yes À Àƒ Áà8;ÁÀ À of CRC errors À À À À À Àƒ Áà8;ÁÀ ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ Àƒ ÃÃNote 1ÄÄ © Only when loss of frame alignment has not yet occurred. ÃÃNote 2ÄÄ © The loss of frame alignment inhibits the process associated with the CRC procedure. ÃÃNote 3ÄÄ © The AIS signal is detected only after the loss of frame alignment fault, so the process associated with the CRC procedure is inhibited. ÃÃNote 4ÄÄ © If CRC errors are detected in frames carrying the RAI signal then CRC error reports should be generated. 5.9.3.3Á  ÁMaintenance functions on the network side 5.9.3.3.1 Defect detection ÁHÁAll the following defect conditions shall be detected by the network side of T interface (NT1, LT, ET functions)(see Note 2): ÁHÁ©Á  Áloss of power on the network side; ÁHÁ©Á  Áloss of incoming signal; ÁHÁ©Á  Áloss of frame alignment (see Recommendation G.706); ÁHÁ©Á  ÁCRC error. ÃÃNote 1ÄÄ © The equipment of the primary rate digital link (NT1, LT,...) have to detect loss of incoming signal and then to generate downstream towards the interface the fault indication signal AIS. ÃÃNote 2ÄÄ © Some equipment in the network may detect only part of the defects or fault conditions listed above. 5.9.3.3.2 Detection of defect indication signals ÁHÁThe following defect indications received at interface shall be detected by the network side: ÁHÁ©Âà  Âremote alarm indication (RAI);ÆÆ ÁHÁ©Á  ÁCRC error informations. 5.9.3.3.3 Consequent actions ÁHÁTable 7/I.431 gives the actions that the network side (NT1, ET functions) has to take after defect detection or defect indication detection. ÃÃNote 1ÄÄ © When the defect conditions have disappeared or the defect indication signals are not received any more, the defect indication signals AIS and RAI should disappear as soon as possible. ÃÃNote 2ÄÄ © The following points are required to ensure that an equipment is not removed from service due to short breaks in transmission: ÁHÁi)Âh   ÂThe persistence of an RAI or of an AIS shall be verified for at least 100 ms before action is taken;ÆÆ ÁHÁii)Âð   ÂWhen an RAI or an AIS disappears, action shall be taken immediately.ÆÆ Áà8SÁƒ Áà8MÁTABLE 7/I.431ƒ Áà8SÁƒ Áà85ÁÃÃDefect conditions and defect indication signals detected by Äă Áà89ÁÃÃthe network side of interface and consequent actions Äă Áà8SÁƒ Áà84ÁÀ ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ Àƒ Áà84ÁÀ À Defect À À Consequent actions À Àƒ Áà84ÁÀ À conditions ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀƒ Áà84ÁÀ À and defect À À Defect indications À Àƒ Áà84ÁÀ À signal À À at interface À Àƒ Áà84ÁÀ À indications ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀƒ Áà84ÁÀ À detected by À À Generation À À Generation À ÀGeneration of À Àƒ Áà84ÁÀ À network side À À RAI À À AIS À ÀCRC error infoÀ Àƒ Áà84ÁÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀƒ Áà84ÁÀ À Loss of power À ÀNot applicableÀ À Yes À ÀNot applicableÀ Àƒ Áà84ÁÀ À on network side À À À À if possibleÀ À À Àƒ Áà84ÁÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀƒ Áà84ÁÀ À Loss of signal À À Yes À À No À À Yes À Àƒ Áà84ÁÀ À À À À À À À (Note 1) À Àƒ Áà84ÁÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀƒ Áà84ÁÀ À Loss of frame À À Yes À À No À À Option 1: No À Àƒ Áà84ÁÀ À alignment À À À À À À Option 2: YESÀ Àƒ Áà84ÁÀ À À À À À À À (Note 3) À Àƒ Áà84ÁÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀƒ Áà84ÁÀ À Detection of À À À À À À À Àƒ Áà84ÁÀ À defect in the À À No À À Yes À À No À Àƒ Áà84ÁÀ À network©to©user À À À À À À À Àƒ Áà84ÁÀ À direction À À À À À À À Àƒ Áà84ÁÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀƒ Áà84ÁÀ À Reception of RAI À À No À À No À À No À Àƒ Áà84ÁÀ À À À À À À À (Note 2) À Àƒ Áà84ÁÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀƒ Áà84ÁÀ À Detection of À À À À À À À Àƒ Áà84ÁÀ À defect in the À À Yes À À No À À No À Àƒ Áà84ÁÀ À user©to©network À À À À À À À Àƒ Áà84ÁÀ À direction up to À À À À À À À Àƒ Áà84ÁÀ À ET À À À À À À À Àƒ Áà84ÁÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀƒ Áà84ÁÀ À Detection of À À No À À No À À Yes À Àƒ Áà84ÁÀ À CRC errors À À À À À À À Àƒ Áà84ÁÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀƒ Áà84ÁÀ À Reception of À À À À À À À Àƒ Áà84ÁÀ À CRC error À À No À À No À À No À Àƒ Áà84ÁÀ À information À À À À À À À Àƒ Áà84ÁÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀƒ Áà84ÁÀ À Excessive CRC À À Yes À À No À ÀNot applicableÀ Àƒ Áà84ÁÀ À error rate À À (Optional) À À À À À Àƒ Áà84ÁÀ ÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀÀ Àƒ ÃÃNote 1ÄÄ © Only when loss of frame alignment has not yet occurred. ÃÃNote 2ÄÄ © If CRC errors are detected in frames carrying the RAI signal then CRC error reports shall be generated. ÃÃNote 3ÄÄ © See CCITT Recommendation I.604. 6.ÁHÁÃÃConnectorÄÄ ÁHÁInterface connectors and contact assignments are the subject of ISO and IEC standards. However, permanent wiring connections of TEs to NTs are also permitted. 7.ÁHÁÃÃInterface wiringÄÄ ÁHÁIn case of symmetrical wiring, the magnitude of the characteristic impedance of the interface cables shall be 120 ohm ÀÀ 20% in a frequency range 200 kHz to 1 MHz and 120 ohm ÀÀ 10% at 1 MHz. ÁHÁFor coaxial interfaces, the magnitude of the characteristic impedance of the interface cables shall be 75 ohm (ÀÀ 5% at 1 024 kHz). 8.ÁHÁÃÃPower feedingÄÄ 8.1ÁHÁÃÃProvision of powerÄÄ ÁHÁThe provision of power to the NT via user network interface using a separate pair of wires to those used for transmission, is optional. 8.2ÁHÁÃÃPower available at the NTÄÄ ÁHÁThe power available at NT via the user©network interface, when provided, shall be at least 7 Watt. 8.3ÁHÁÃÃFeeding voltageÄÄ ÁHÁThe feeding voltage for the NT shall be in the range of ©32 to ©57 volt. ÁHÁThe polarity of the voltage towards ground shall be negative. 8.4ÁHÁÃÃSafety requirementsÄÄ ÁHÁIn principle safety requirements are outside the scope of this Recommendation. However, in order to harmonize power source requirements the following information is provided: ÁHÁi)Âh   Âthe voltage source and the feeding interface should be protected against short circuit or overload. The specific requirements are for further study;ÆÆ ÁHÁii)Âð   Âthe power input of NT1 shall not be damaged by an interchange of wires.ÆÆ ÁHÁWith respect to the feeding interface of the power source, which is regarded as a touchable part in the sense of IEC Publication 950, the protection methods against electric shock specified in IEC Publication 950 may be applied. Áà8SÁƒ Áà8OÁAnnex A ƒ Áà8SÁƒ Áà8FÁ(to Recommendation I.431) ƒ Áà8SÁƒ Áà86ÁÃÃTime slot assignment for interfaces having only H0 ChannelsÄă ÁHÁThe following are examples of fixed assignment of time slots when only H0 Channels are present at the interface. ÁHÁi)Á   Á1544 kbit/s interface *  This fourth H0 Channel is available if time slot 24 is not used for a    D Channel. ÁHÁii)Á   Á2048 kbit/s interface ÁHÁExample 1 ÁHÁExample 2 ÃÃNoteÄÄ © The time slot assignment in Example 2 is the one described in Recommendation G.704 for n x 64 kbit/s interface with N = 6 and fixed first time slot allocation. It is therefore the preferred assignment. Áà8SÁƒ Áà8PÁAnnex Bƒ Áà8SÁƒ Áà8GÁ(to Recommendation I.431)ƒ Áà8SÁƒ Áà82ÁÃÃTime slot assignment for 2048 kbit/s interfaces having H11 ChannelÄă ÁHÁThe following is an example of fixed assignment of times slots when H11 Channel is present at the interface. ÃÃNoteÄÄ © Time slot 16 is to be assigned to the D Channel, when this channel is present. Time slots 26 to 31 may be used for H0 Channel or six B Channels. Áà8KÁAppendix I/I.431ƒ Áà8SÁƒ Áà8@ÁÃÃPulse mask for interface at 1544 kbit/sÄă ÁHÁAn isolated pulse, when scaled by a constant factor, shall fit the pulse mask shown in Figure I©1/I.431. ÃÃNoteÄÄ © UI = Unit Interval = 647.7 ns Áà8KÁFIGURE I©1/I.431ƒ Áà8@ÁÃÃPulse mask for interface at 1544 kbit/sÄă