01b_physical interface configuration_dn03549536_5_en_global_pdf_paper_a4_d.pdf

Physical Interfaces Configurationand Supervision for RNC

dn03549536Issue 5 en

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RNC3059Nokia WCDMA RNC, RN2.1, ProductDocumentation (PDF)

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Physical Interfaces Configuration and Supervision for RNC

Contents

Contents 3

1 Physical interfaces in ATM network 5

2 ATM over PDH 9

3 IMA, Inverse Multiplexing for ATM 11

4 SDH transmission 15

5 SONET interface 19

6 SDH transmission protection 21

7 Transmission Convergence sublayer (TC) 25

8 Physical layer Trail Termination Point (phyTTP) 27

9 PDH supervision 29

10 IMA supervision 33

11 SDH supervision 35

12 Configuring PDH for ATM transport 37

13 Creating IMA group 41

14 Configuring SDH for ATM transport 45

15 Creating SDH protection group 49

16 Creating phyTTP 53

17 Interface-specific TC measurement shows transmission errors 55

18 STM-1 measurement shows transmission errors 57

Related Topics 59



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Contents

1 Physical interfaces in ATM network

Physical interfaces are used for connecting the network element to externaltransmission networks. They provide the means to execute physical layerfunctionality, such as O&M, ATM and TDM traffic mapping to the transmissionframe structure of Synchronous Digital Hierarchy (SDH), Plesiochronous DigitalHierarchy (PDH), or Ethernet. One network interface unit includes one or morephysical interfaces depending on the unit type.

Figure 1. Physical interfaces for PDH/SDH transmission

The RNC provides the following physical interface types:

. E1/T1/JT1 PDH ATM interfaces

. STM-1 (VC-3/4) SDH ATM interfaces

PDH interfaces can be either in T1, E1, or JT1 mode.

MXUNIP1E1/T1/JT1

ATM

NIS1P

NIS1

STM-1/VC-4STM-1/VC-3

ATMSFU



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Physical interfaces in ATM network

. E1 is the European PCM system (ETSI) that carries 30 channels in a 256-bit frame transmitted at 2.048 Mbit/s basic multiplex rate.

. T1 is the American PCM system that carries 24 channels in a 193-bit frametransmitted at 1.544 Mbit/s basic multiplex rate. It is used in USA, Canada,and other ANSI countries. Note that T1 does not support SSM(Synchronisation Status Messages).

. JT1 is the Japanese system based on the US T1 interface that carries 24channels in a 193-bit frame transmitted at 1.544 Mbit/s basic multiplexrate.

PDH-based ATM interfaces are used for providing low speed link connections atE1, T1, or JT1 rates between ATM network elements. ATM access via E1/T1/JT1offers a universal communication method for integrating data, video, and voiceon a common network and is cost-effective.

PDH interfaces are especially suitable for links between RNC and the WCDMABTS (base station) where the bandwitdh requirements are low and capacity andcost optimisation is necessary. ATM PDH interfaces have Inverse Multiplexingfor ATM capability (IMA), which provides flexible transmission capacitybuilding.

The supervision of PDH interfaces is provided by the Trunk NetworkMaintenance function.

Different types of physical media can be used for PDH interfaces. That is why theimpedance of the interface must be configurable to achieve impedance matching.The possible values are listed in the following table.

Table 1. Physical media types for PDH interfaces

Interface Physical media type

E1 75 ohm with coaxial pair

120 ohm with symmetric pair

T1 and JT1 100 ohm with symmetric pair

Synchronous Digital Hierarchy (SDH) forms the basis of transport of the ATMtraffic especially in backbone networks in the Iu interface. The RNC provideshigh bit rate SDH STM-1 ATM interfaces. SDH transmission protection (MSP 1+1) and SDH interface unit protection are provided.

Note




SONET APS 1+1 protection is not supported.

Synchronous Optical Network (SONET) is, like SDH, a transfer mode that isdesigned to run on optical fiber. SONET is standardised by ANSI and used in theUnited States and Canada. It is a variation of the SDH international standard.

Physical interfaces supervision

In ATM traffic, the physical layer is supervising the Physical Layer TrailTermination Point (phyTTP). In fault situations concerning ATM traffic, thephysical layer informs the ATM OAM, and the operational state of the ATMinterface will be changed. The physical layer also collects statistics on thedisturbances detected on the Transmission Convergence (TC) sublayer.

Figure 2. Physical interfaces supervision for ATM traffic

Network interface units

The system makes decisions on setting and cancelling alarms and collectsdisturbance statistics according to the information it receives from the networkinterface units (NIU). NIUs are functional units controlling the exchangeterminals.

AAL Layer

ATM Layer

IMA

Traditional TC

PDHE1/ T1/JT1

SDHSTM-1

TransmissionConvergenceSublayer

PhysicalMediumSublayer

PhysicalLayer



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There are four types of network interface units for the ET, PET and SET exchangeterminals. Each NIU includes one or more of these physical interfaces (exchangeterminals), which can be configured to be used in different interfaces of the RNC.For example, the NIUs used in the Iu interface include NIS1 and NIP1. NIUsconnect physical interfaces to the supervising signalling computer units throughATM Multiplexer units (MXU) and the ATM Switching Fabric Unit (SFU).

The various physical interfaces available in the RNC are presented in thefollowing figure.

Figure 3. Physical interfaces in the RNC

16 x PET

4 x SET

4 x SET

NIP1

NIS1P

NIS1

MXU

SFU




2 ATM over PDH

The existing transmission networks are widely based on Plesiochronous DigitalHierarchy (PDH). PDH is a transfer mode in which the timing relationship of thecorresponding significant instants of a signal is not limited. Although theSynchronous Digital Hierarchy (SDH) forms the basis of ATM traffic transport,there is also need to transport ATM cells using PDH transmission networks. InRNC, PDH ATM is used for the following connections:

. towards another Radio Network Controller (Iur interface)

. towards Base Station (Iub interface)

. towards Multimedia Gateway (Iu-CS interface)

. towards Serving GPRS Support Node (Iu-PS interface)

. towards Cell Broadcast Centre (Iu-BC interface)

PDH-based ATM interfaces are used for providing low speed link connectionsbetween ATM network elements. PDH interfaces are especially suitable when thebandwitdh requirements are low, and capacity and cost optimisation is necessary.

The task of the network interface unit (NIP1) is to provide PDH externalinterfaces and the means to execute physical layer and ATM layer functionality.The NI16P1A plug-in unit provides 16 E1/T1/JT1 ATM interfaces (exchangeterminals). The exchange terminal used for ATM connections is PET, PDHExchange Terminal.

ATM cells are mapped to E1 or T/JT1 transmission frames. The cell rateadaptation to the payload capacity of the PDH frame is performed by the insertionof idle cells when valid cells are not available from the ATM layer. The HeaderError Control (HEC) value is generated and inserted in the specific field of theATM cell header. The cell delineation is performed based on the HEC field ofATM cell.

The Transmission Convergence (TC) sublayer provides the transport of cellstreams. For more information on Header Error Control and other TC functions,see Transmission Convergence sublayer (TC).



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ATM over PDH

Fractional E1/T1/JT1

Fractional E1/T1/JT1 provides configuration of lower capacity physical ATMinterfaces. It is necessary for supporting N x 64 kbps metallic leased lines on theIub interface. IMA functionality is not supported over fractional E1/T1/JT1 lines.

ATM cells are mapped on a circuit-mode connection with unrestrictedinformation transfer rates at integer multiples of 64 kbit/s up to the maximum rateof the interface. This applies for any N*64 kbit/s rate up to 1920 kbit/s.

Normally in E1, the timeslot 16 cannot be used for carrying user traffic. In afractional E1 you can select the timeslots that are used for user data. You canconfigure the timeslot 16 for this function as long as the receiver supports it aswell. This way you can have more capacity for user traffic (31 out of 32timeslots).

PDH/ATM network interface units

NIP1 Network interface unit E1/T1/JT1

The task of the network interface unit NIP1 is to provide 2Mbit/s PDH external interfaces and the means to executephysical layer and ATM layer functionality.

The unit maps ATM cells to and from the transmission framestructure of PDH (E1, T1 or JT1) and includes ATM layerfunctions such as header translation, OAM functions, andtraffic management. NIP1 also provides an optional referenceclock to timing and synchronisation.

Plug-in unit NI16P1A provides 16 E1/T1/JT1 ATM interfaces(exchange terminals) with IMA functionality. These interfacescan be used to form ATM interfaces over conventional PCMconnections.

PET PDH Exchange Terminal

Physical interface for one PDH E1/T1/JT1 interface used forATM connections. PETs can also be used to form IMAgroups.




3 IMA, Inverse Multiplexing for ATM

The purpose of Inverse Multiplexing for ATM (IMA) is to combine the capacityof many lower bit rate transmission lines into a group that is seen as a singlevirtual link by the ATM layer of a network element.

The IMA provides modular bandwidth for user access to ATM networks and forconnections between ATM network elements at rates between traditional ordermultiplex levels, for example between E1 or E3 levels.

The IMA involves inverse multiplexing and de-multiplexing of ATM cells in acyclical fashion among links grouped to form a higher bandwidth logical linkreferred to as an IMA group. The rate of the IMA group is approximately the sumof the link rates.

Multiplexing of the ATM cell stream is performed on a cell by cell basis acrossthe multiple links. The IMA sublayer is part of the physical layer. It is locatedbetween the traditional Transmission Convergence (TC) sublayer and the ATMlayer according to the following figure.

An IMA group is terminated at each end of the IMA virtual link. The ATM cellstream received from the ATM layer is distributed on a cell by cell basis acrossthe multiple links within IMA group. At the far end, receiving IMA recombinesthe cells from each link, on a cell by cell basis, creating the original ATM cellstream(s).



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IMA, Inverse Multiplexing for ATM

Figure 4. Principle of Inverse Multiplexing for ATM

The NIP1 network interface unit supports the configuration of up to 8 physicallinks per IMA group. Up to 8 IMA groups can be provided per unit.

The supported IMA configuration is symmetric which means that there must bethe same amount of physical links both in ingress and egress direction.

The length of the IMA frame is 128 which contains one IMA Control Protocolcell and 127 ATM cells. The length of the IMA frame is fixed.

The IMA groups are created at both ends of the transmission lines, which are seenas one virtual IMA link. The PDH exchange terminals at both ends of the IMAvirtual link have to be tied up to the same kind of functional units. The maximumnumber of transmission lines that can be grouped into one IMA group is 8 x E1 (2Mbit/s) lines or 8 x T1/J1 (1,5 Mbit/s) lines.

When creating IMA groups, the transmission lines are identified with the PDHexchange terminals (PETs) that they are connected to. All the PETs of one IMAgroup have to belong to the same NIP1 functional unit. There can be several IMAgroups per one functional unit.

A PET can only belong to one IMA group. However, a PET can be transferredfrom one IMA group to another provided that the groups share the samefunctional unit. When transferring a PET from one group to another, you mayalso have to make changes in the switching.

Note

PETs can be added to and deleted from an IMA group while the functional unit isactive and the IMA group is already tied up to an ATM interface. However, you

Single ATM CellStream from ATMLayer

IMAGroup

PHYLayer

PHYLayer

PHYLayer

PHYLayer

PHYLayer

PHYLayer

IMAGroup

Original ATM CellsStream passed toATM Layer

Physical Link#2

Physical Link#3

Physical Link#1

IMA Virtual Link




cannot remove an exchange terminal from the IMA group if the capacity of theIMA group would become smaller than the used capacity of the ATM interface.In practice, you must configure the IMA group so that the IMA group capacity,that is, the total number of links, equals or is greater than the used capacity of theATM interface.



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4 SDH transmission

Synchronous Digital Hierarchy (SDH) is a transfer mode in which there arespecified limits to the timing relationship of the corresponding significant instantsof a signal. SDH forms the basis of transport especially in backbone networks.SDH interfaces are used for connecting the network element to SDH-based IP/ATM networks. In the RNC, ATM SDH is used for the following connections:

. towards another Radio Network Controller (Iur interface)

. towards Multimedia Gateway (Iu-CS interface)

. towards Base Station (Iub interface)

. towards Serving GPRS Support Node (Iu-PS interface)

. towards Cell Broadcast Centre (Iu-BC interface)

ATM Megalink Service's SDH protocol is used in Japan, while SONET is theequivalent transfer mode used in ANSI countries.

Note

SDH terms are generally used in Nokia documents. For the differences interminology, see SONET interface.

In order to ensure the cell delineation performance, SDH-based physical layersuse a self-synchronising scrambler with polynomial x7 + x6 + 1 to scramble theSTM-1 frame.

STM-1 interface

ITU-T SDH is the standard used in the SDH transmission for RNC. For ATMtraffic, it is also possible to configure the network according to ATM MegalinkService's SDH protocol in Japan.



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SDH transmission

STM-1 SDH interface is an SDH interface at 155 520 kbit/s. It provides VC-3and VC-4 mapping of ATM cells.

The task of the NIS1 network interface unit is to provide STM-1 externalinterfaces and the means to execute physical layer and ATM layer functionality.The NI4S1 plug-in unit can be configured as non-redundant (NIS1) or 2Nredundant (NIS1P). The SDH exchange terminal type is SET.

SDH is divided into three different layers: Regenerator Section, MultiplexSection, and Path.

Figure 5. SDH layers

From the SDH transmission network point of view, the RNC equals to theTerminal Multiplexer presented in the figure.

Note

In SONET, the layers are section (regenator section), line (multiplex section) andpath. For the differences in terminology, see SONET interface.

The Transmission Convergence (TC) sublayer provides the transport of cellstreams. For more information on Header Error Control and other TC functions,see Transmission Convergence sublayer (TC).

Path

Multiplex

Section

Multiplex

Section

Multiplex

Section

Regenerator

Section

Regenerator

Section

Regenerator

SDH

Multiplexer

SDH

Multiplexer




The RNC provides optical single mode fibre STM-1 interfaces. The transmissionmedium consists of two single-mode fibres, one for each direction.

Table 2. STM-1 interface specifications

Interface type STM-1 optical (ITU-T G.957, table 1)

Bit rate 155 520 kbit/s

Mapping VC-4: One logical ATM interface, capacity 149 760kbit/s.

VC-3: Three logical ATM interfaces, capacity 3 x 48384 kbit/s

Nominal wavelength (nm) 1310

Medium G.652 optical fibre (SM)

Connectors LC

OAM F3 I.432.2 / G.707 POH

OAM F2 I.432.2 / G.707 SOH

OAM F1 not used

Number of interfaces Four optical interfaces per plug-in unit

Transmission protection MSP 1+1

In order to provide reliable connections, supervision and maintenance functionsare provided for the Physical Medium sublayer and the TransmissionConvergence sublayer. The most essential function is Operation and Maintenance(O&M), which includes performance monitoring, defect and failure detection,system protection, defect information, and fault localisation.

SDH network interface units

NIS1 Network interface unit STM-1

The task of NIS1 is to provide STM-1 external interfaces andthe means to execute physical layer and ATM layerfunctionality. NIS1 units map ATM cells to and from thetransmission frame structure of SDH. It includes ATM layerfunctions such as VC-3/4 mapping, header translation, UPC/NPC parameter control, OAM functions, traffic management,performance monitoring and performance data collection.



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SDH transmission

NIS1 supports MSP 1+1 transmission protection andequipment protection (2N) of SDH interfaces. It also providesan optional reference clock to Timing and Synchronisation. Itis not a 2N redundant unit and it does not support plug-in unitlevel protection.

Plug-in unit NI4S1-B provides 4 optical STM-1 interfaces.

NIS1P Network interface unit STM-1 with equipment protection

This unit has the same features as the NIS1 except that it isused when plug-in unit level protection is required. It is a 2Nredundant unit. It does not start unless the pair functional unitis created in the system.

SET SDH Exchange terminal

Physical interface for one optical STM-1 interface.




5 SONET interface

SONET (synchronous optical network) is, like SDH, a transfer mode that isdesigned to run on an optical fiber. SONET is standardised by ANSI and used inthe United States and Canada. It is a variation of the SDH international standard.

SONET hierarchy is comparable to SDH, but it uses a slightly differentterminology. The SONET layers are called section, line and path. The SONETtransport modules are OC (optical carrier) in the optical level, and STS(synchronous transport signal) in the electrical level.

The user interface presents the information according to SDH terminology. Thefollowing table provides translation of the most important terms.

Table 3. SONET and SDH terminology

SONET (optical level) SDH Additional information

Section Regenator section

Line Multiplex section

Path Path

OC-1 STM-0 51 840 kbit/s

STS-1 in electrical level

OC-3 STM-1 155 520 kbit/s

STS-3 in electrical level

OC-3 VC-3/STM-1 Payload capacity: 3 x 48 384 kbit/s

OC-3C VC-4/STM-1 Payload capacity: 149 760 kbit/s

SPE (SynchronousPayload Envelope)

VC

APS 1+1 MSP 1+1



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SONET interface

Table 3. SONET and SDH terminology (cont.)

SONET (optical level) SDH Additional information

VTG TUG-2

VT1.5 SPE VC-11

VT2 SPE VC-12

VT1.5 TU-11

VT2 TU-12

Note

Note! OC-1 is not supported in this release.




6 SDH transmission protection

SDH transmission protection covers Multiplex Section Protection (MSP) andequipment (network interface unit) protection for SDH STM-1 interfaces.

Multiplex Section Protection

Multiplex Section trail linear protection is used to protect a single multiplexsection trail by replacing a working MS trail if the working trail fails or if theperformance falls below the required level. You can configure SDH protectiongroups for this purpose.

This release supports both ITU-T's and ANSI's definitions of bi-directionalMultiplex Section Protection 1+1. The ITU-T's definition is referred here as MSP1+1 compatible with 1:n protocol (Recommendation G.841, Section 7.1).Whereas the ANSI�s definition is referred as APS 1+1 (RecommendationT1.105.01-2000, Section 6). Both of these Multiplex Section Protections can beused either in revertive or in non-revertive mode.

The supported Multiplex Section Protection 1+1 is a bi-directional protectionswitching mode where the traffic is carried via two multiplex sections. Theprotection switching protects the multiplex section layer in point-to-pointphysical networks. It is applicable to all SDH interfaces regardless of payload orVC mapping. The MSP functions, at the ends of a multiplex section, makerequests for and give acknowledgments of switch action by using the MSP bytes,that is K1 and K2 bytes, in the MSOH of the protection section.

In 1+1 protection the traffic is always transmitted on both working and protectiontrails which means that in the egress direction the traffic is copied to bothsections. In the reception direction the selector is used to select the traffic fromeither working section or protection section.

In the revertive mode the selector returns automatically to the working sectionafter its recovery. Before the selector returns to the working section it is waitedthat there are no signal degrade or signal fail conditions on working sectionduring the time defined by wait to restore time. The automatic returning is alsoprevented if there is an active switch command, for example, forced switch toprotection section which selects the traffic from the protection section.



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SDH transmission protection

NIS1, NIS1P, IWS1E and IWS1T units support both of the MSP1+1 compatiblewith 1:n protocol and ASP 1+1 both in revertive and non-revertive modes.

Figure 6. SDH transmission protection MSP 1 + 1

Network interface unit protection

There are redundant and non-redundant SDH network interface units (NIUs).NIS1, IWS1E and IWS1T are non-redundant units, whereas NIS1P is aredundant, 2N duplicate unit.

In the normal operation of a redundant unit, one NIU is in WO-EX state and theother is in SP-EX state. A hardware defect of the protected SDH NIU pair or thestate change of the NIU to other than WO or SP, initialises the switchingoperation. When one NIU of the SDH NIU pair is faulty, the traffic in ingressdirection must be selected from the other NIU. When the state of a NIU has beenchanged to some other than WO or SP, all incoming traffic must be selected fromthe working NIU.

Note

. Protected NIU:

You must configure the SDH interface protection for a protected, 2Nredundant NIU pair (NIS1P) so that the SETs of the protection group arelocated in different NIUs.

fault in the working section

protection section

IPA2800SDH

Multiplexer

FAILURE CASE

working section

protection section

IPA2800SDH

Multiplexer

NORMALOPERATION

MSP 1+1




. Unprotected NIU:

When the equipment protection is not used together with the transmissionprotection, both SETs in the protection group must be located in the sameNIU.

The system generates the 0101 SDH PROTECTION SWITCHING EXECUTEDnotice when the protection switch operation is completed successfully, and the3183 SDH PROTECTION SWITCHING FAILED alarm in case of the protectionswitch operation fails. The 3334 FAR END PROTECTION SECTION FAILUREalarm is set when the system detects that the far end of the protected multiplexsection is not able to use the protection section. This alarm is an indication thatthe protection section can not be used, for example, in case of the working sectionfails.

When using the ANSI definition of the multiplex section protections, for exampleAPS 1+1 protocols, the system generates alarm 3307 MISMATCH IN SONETAPS CONFIGURATION when there is configuration mismatch between the nearend and the far end network elements which implement the multiplex sectionprotection. Both the near and the far ends must support the APS 1+1 protocolsbefore the alarm can be set. The system monitors that the far end are using 1+1protection switching architecture and that the used mode of operation is bi-directional.

Alarm 3183 may cause the traffic is cut which depends on the failure situationand the section condition where selector is.



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7 Transmission Convergence sublayer(TC)

The Transmission Convergence (TC) sublayer enables the transport of cellstreams. It adapts the cells to framing and physical transmission media, such asPDH ATM transmission and SDH transmission.

The ATM cell header contains a HEC field which is used to achieve celldelineation. Cell delineation is the process which allows the identification of thecell boundaries. The transmitter calculates the HEC value across the entire ATMcell header and inserts the result in the appropriate header field. The receiverchecks HEC against the ATM cell header and corrects errors if it is possible. Ifthere are more errors than one in the header, it cannot be corrected but the cell isdiscarded.

A valid HEC for the proceeding four octets in the stream is sought according to adefined hunting mechanism (ITU-T I.432).

The ATM cell payload (48 bytes) is scrambled before mapping into thetransmission frame with polynomial x43 + 1. The ATM cell payload is alwaysscrambled in NIS1 and NIS1P units, while in NIP1 and NIP1P units thescrambling can be turned on and off. In the reverse operation, followingtermination of the signal, the ATM cell payload will be descrambled before beingpassed to the ATM layer. Cell payload scrambling is used to improve the securityand robustness of the HEC cell delineation mechanism. In addition, it helpsrandomising the data in the information field for possible improvement of thetransmission performance.

After the cell header verification all the physical layer cells will be extracted andonly the valid cells are passed to the ATM layer. Cell rate decoupling is theadaptation of the ATM layer bit rate to the physical layer PDH/SDH transmissionframe bit rate by insertion of idle cells at the transmitting side. The idle cells arediscarded at the receiving side.



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Transmission Convergence sublayer (TC)

TC supervision

The Transmission Convergence sublayer generates one alarm in case of faultsituation: Loss of ATM cell delineation, alarm number 3904. This alarm willcause the traffic is cut.




8 Physical layer Trail Termination Point(phyTTP)

The Physical layer Trail Termination Point (phyTTP) is used for hiding theproperties of the physical resources from the upper protocol layers. It isconfigured between the physical layer and the ATM layer. A phyTTP ID is givenwhen configuring the ATM interface. The phyTTP can be used to transport theprotocol data units of the upper layer, for example ATM cells.

Configure the phyTTP after having configured the SDH or PDH interfaces. TheMML for creating phyTTP includes a parameter, payload type, for separatingATM traffic from PPP traffic. However, only ATM traffic is supported in thisrelease.

The physical layer supervises the phyTTP for detecting failures in ATMtransmissions. For more information, see Physical interfaces supervision.

Figure 7. Physical layer Trail Termination Point (phyTTP) for an ATM interface

VC-3/4path

PET(E1/T1/JT1)

VC-3/4path

VC-3/4path

PET(E1/T1/JT1)

PET(E1/T1/JT1)

IMA groupSDHprotectiongroup

phyTTPPhysical layer

logical ATM interfaceATM layer



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Physical layer Trail Termination Point (phyTTP)

9 PDH supervision

The Trunk Network Maintenance supervises continuously all operational trunkPDH E1/T1/JT1 connections between network elements. In fault situations, itinforms the call control system about the disturbances and issues alarms. It alsocollects statistics on the disturbances detected on the PDH connections.

The PDH E1/T1/JT1 connections can be used to form PDH-based and ATMconnections (PETs).

The supervision functionality is activated automatically by the system when thestate of the supervised PET is changed into WO-EX.

In case of a fault on an active trunk circuit the network interface unit sends anerror message to the system. The system notifies the maintenance personnel bysetting an appropriate alarm and runs the needed maintenance operations toinform the remote end about the fault. The faulty connection is automaticallyisolated from traffic until it is back in order. During that time new traffic is huntedusing the correctly working trunk connections.

When the network interface unit detects a fault on one of its trunk circuits, itreports the fault to the system.

The system keeps the call control up-to-date on the availability of individualtrunk circuits. After the cause of a disturbance-specific alarm has disappeared, thesystem automatically releases the circuit back into use. If the fault has also causedan FRM alarm, the circuit will be taken into use first after the cancelling delay ofthe FRM alarm.

The maintenance operations in different fault situations are presented in the tablebelow. The alarms 1900 and 2925 are not used in PETs (exchange terminal forPDH-based ATM connections).



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PDH supervision

Table 4. Maintenance operations for PDH alarms

Fault name (alarm number) Alarm signal toremote end

AIS to switchingnetwork

Degraded slip frequency (1900)

Incoming signal missing (2900) X X

PCM line remote end alarm, E1 (2902) / Yellowalarm T1/JT1 (2944)

AIS received, E1 (2909) / Blue alarm, T1/JT1(2943)

X X

Framing error (2910) X X

Bit error rate over limit (2912) X X

CRC bit error ratio over limit (2923)

Remote end CRC bit error ratio over limit (2924)

Slip frequency limit exceeded (2925)

Disturbance-specific alarms

The system uses two types of alarms to notify the user about faults anddisturbances on trunk circuits: disturbance-specific alarms and FRM alarm.

In this context, a disturbance is a temporary, exceptional fault situation on a trunkcircuit which is caused by an external phenomenon. When the external causedisappears, also the fault situation is over. For example, climatic factors can causetemporary disturbances to the transmission network.

Each trunk circuit is equipped with counters collecting information ondisturbances. You can define the alarm limits separately for each disturbancetype. If the duration of a disturbance on a trunk circuit exceeds your disturbance-specific alarm filtering limit, the system issues an alarm and runs the appropriatemaintenance operations to inform the maintenance personnel and the remote endabout the fault.

The disturbance types are the following:

. incoming signal missing

. frame alignment lost




. AIS received

. alarm from the remote end

. bit error ratio 1E-3 exceeded

. CRC errors

The CRC errors are only monitored when CRC-4 (E1 interfaces) or ESF(T1/JT1 interfaces) framing is on.

You can modify and view the filtration limits of disturbance-specific alarms andtheir cancellation times by using the YEA and YEP commands.

Fault Rate Monitoring (FRM) alarm

You can use the FRM alarm to supervise the general service quality of the PDHE1/T1/JT1 connetions. The system issues the FRM alarm in the followingsituations:

. The duration of a disturbance-specific alarm on a connection exceeds thepredefined time limit.

. The amount of short disturbances on a connection exceeds the predefinedtime limit (the short disturbances are disturbances which do not last longenough to trigger any disturbance-specific alarms). The call control isolatesthe faulty connection from the traffic. It becomes operational again afterthe predefined FRM alarm cancel delay time has elapsed.

You can adjust the sensitivity and the cancelling delay of the FRM alarm by usingthe YEM command.



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PDH supervision

10 IMA supervision

The IMA failure alarms and their definitions are presented in the following table.

Table 5. IMA alarms

Fault name (alarmnumber)

Definition

Loss of IMA frame (3910) The loss of the IMA frame detected in one link of the IMA group. There are trafficdisturbances or traffic of the IMA group is completely cut.

IMA link out of delay sync(3911)

The link differential delay between one link and the other links in the group is overtolerable. The traffic of the IMA group does not function properly.

IMA Tx misconnected(3913)

The transmit side (Tx) of a link is not connected to the same far-end IMA unit asthe other Tx links in the group.The traffic of the IMA group does not functionproperly.

IMA Rx misconnected(3914)

The receive side (Rx) of a link is not connected to the same far-end IMA unit asthe other Rx links in the group. The traffic of the IMA group does not functionproperly.

IMA Tx link unusable FE(3915)

The far-end IMA unit reports that the receive side (Rx) link is unusable. The trafficof the IMA group does not function properly.

IMA Rx link unusable FE(3916)

The far-end IMA unit reports that the receive side (Rx) link is unusable. The trafficof the IMA group does not function properly.

IMA start-up FE (3917) The far-end IMA unit remains in its start-up state. IMA connection could not beestablished.

IMA configurationaborted (3918)

The far-end IMA unit tries to use unacceptable configuration parameters. Thetraffic of the IMA group does not function properly.

IMA configurationaborted FE (3919)

The far-end IMA unit tries to use unacceptable configuration parameters. Thetraffic of the IMA group does not function properly.

IMA insufficient links(3921)

There are not enough links in the IMA group. It may not be capable of transportingall the data it should.



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IMA supervision

Table 5. IMA alarms (cont.)

Fault name (alarmnumber)

Definition

IMA insufficient links FE(3922)

Far-end IMA unit reports that there are not enough links in the IMA group. Thetraffic of the IMA group does not function properly.

IMA blocked FE (3923) Far-end IMA group reports that it is blocked. The IMA group is out of use.

IMA group timingmismatch (3924)

Far-end (FE) transmit clock mode is different from the near-end (NE) transmitclock mode. The traffic of the IMA group does not function properly.

RFI IMA (3925) IMA related remote defect detected. Traffic of the IMA group does not functionproperly.




11 SDH supervision

The physical layer takes care of the operations and maintenance functionality foroptical SDH interfaces. Fault management and performance managementfunctions related to OAM flows F1, F2 and F3 are also covered.

Most of the functions of the physical layer OAM are implemented by hardware,which provides the Section Overhead (SOH) and Path Overhead (POH) byteshandling, regenerator section, multiplex section, and path level alarm detection,and performance monitoring. Software is used to initialise and monitor hardwareand to provide access dependent failure indications for alarm system, networkmanagement, and ATM layer management.

The functionality is activated automatically by the system when the state of theSDH exchange terminal (SET) is changed into WO-EX. Note that SETs do nothave the operational state SP-EX. When the operational state of the networkinterface unit is SP-EX, the state of the SET is WO-EX.

The alarms are set to the alarm system in different levels. The Nokia NetAct usesthese alarms.

Table 6. SDH alarms available via alarm system

Fault name (alarm number) SPI RS MS PathHOVC

PathLOVC

TU

Transmit Fail TF (2784) X

Loss of Signal LOS (3900) X

Loss of Frame LOF (3902) X

Loss of Pointer LOP (3903, 3980) X X

Remote Defect Indication RDI (3906,3907, 3978)

X X X

Signal Label Mismatch SLM (2937,3985)

X X



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SDH supervision

Table 6. SDH alarms available via alarm system (cont.)

Fault name (alarm number) SPI RS MS PathHOVC

PathLOVC

TU

Alarm Indication Signal AIS (2938,3905, 3977)

X X X

Unequipped SDH VC Signal (3941,3984)

X X

Excessive Errors in Incoming SDHSignal (3964)

X

Loss of multiframe LOM (3976) X

Incoming SDH Signal Degraded(3979)

X

SPI Synchronous Physical Interface

RS Regenerator Section

MS Multiplex Section

HOVC Higher Order Virtual Container

LOVC Lower Order Virtual Container

TU Tributary Unit

Note

All of the alarms will cause that the traffic is not working properly.

The protection group provides protection against the traffic is cut when the alarm(2784, 3900, 3902, 2938, 3964 or 3979) is only for one of the SETs of theprotection group.




12 Configuring PDH for ATM transportPurpose

This procedure describes how you can configure PDH/ATM interface for theNIP1 interface unit. The mode of the PDH interface must be the same for all theexchange terminals in the plug-in unit. That is why the NIP1 unit must be givenas a parameter when the PDH mode is configured.

Usually the existing default values for the PDH supervision are adequate and youdo not have to change them. If needed, you can configure and modify theexchange terminal supervision parameters.

When you have configured new PETs, you may have to modify their functionalmodes. Choose either E1, ETSI specific functional modes, or T1, ANSI specificfunctional modes. In a fractional E1/T1/JT1 you can select the timeslots that areused to carry user data.

Note

IMA functionality is not supported over fractional E1/T1/JT1 lines.

The network elements provide a synchronisation interface for external timingreference signals. For information on synchronisation, see Configuringsynchronisation inputs in Synchronisation and Timing.

Before you start

You must have created a functional unit description for the exchange terminals(PET). For the instructions, refer to Creating and attaching functional unitdescription in Hardware Configuration Management.

Steps

1. Interrogate the PET's current configuration (YAI)



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Configuring PDH for ATM transport

ZYAI:PET;

2. Set the interface operation mode of NIP1 (YAE)

Set the operation mode if you want to change it. The impedanceparameter can be given only if the operation mode given is E1.

ZYAE:NIP1,<network interface unit index>,<interfaceoperation mode>:[<impedance>];

If you change the impedance or the operation mode, you must restart theunit so that the changes are taken into use. See the instructions inRestarting functional unit in Recovery and Unit Working StateAdministration.

3. Modify E1 functional modes if needed (YEC)

You can first output the ETSI specific frame modes with the command

ZYEI;

If the current frame mode does not match with the frame mode of theinterface unit that is connected to the remote end of this line, you canmodify it with the command

ZYEC:<unit type>,<unit index>:NORM,(DBLF|CRC4);

Note

Double framing does not support SSM. For more information, see Configuringsynchronisation inputs in Synchronisation and Timing.

4. Modify T1 functional modes if needed (YEG)

You can output the ANSI specific T1 functional modes with the command

ZYEH;

If the current frame mode does not match with the frame mode of theinterface unit that is connected to the remote end of this line, you canmodify it with the command




ZYEG:<unit type>,<unit index>:(ESF|SF),(B8ZS|AMI),(0|7.5|15|22.5);

Note

T1 does not support SSM. For more information, see Configuringsynchronisation inputs in Synchronisation and Timing.

5. Configure PET (YAM)

ZYAM:PET,<PET index>...:[ON|OFF]:[DIA=(ON|OFF)|LINE=ON|OFF)]...:[<SA bit number SSM>];

6. Modify PET timeslot usage (YAW)

You can modify PET timeslot usage with the command

ZYAW:<PET index>...:<timeslot number>...,[ON|OFFdef];

7. Create an IMA group, if necessary

If you want to use more than one transmission line, you must create anIMA group for the physical links. Configure PET (YAM) and Modify PETtimeslot usage (YAW) are repeated for each link which is selected to theIMA group. See instructions in Creating IMA group for more information.

8. Create physical layer Trail Termination Point

See instructions in Creating PhyTTP for more information.

Example 1. Configuring PDH for ATM transport

1. Set the interface operation mode of NIP1 with index number 9 to T1.

ZYAE:NIP1,9,T1;

2. Restart the unit.

ZUSU:NIP1,9;

3. Modify the frame alignment mode of the T1 PET with index 9.

ZYEG:PET,9:ESF,B8ZS,0;



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4. Disable scrambling for PETs with indexes between 9 and 15.

ZYAM:PET,9&&15:OFF::;

5. Create a phyTTP with ID 2 of PET with index 9.

ZYDC:2:PET=9;




13 Creating IMA groupPurpose

This procedure describes how you can create an IMA group and add exchangeterminals to it. You can later connect an external ATM interface to the phyTTPthat has been created for the IMA group.

The bandwidth of the IMA group is approximately the sum of the linkbandwidths. In case of a link failure the effects of the failure depend on theamount of bandwidth used from the IMA group and on the type of traffic, butonly if, after the link failure, the number of working links is higher than theminimum number of links. If the number of working links is lower than theminimum number of links after the link failure, dimensioning or type of traffic donot matter.

If you are using the entire bandwidth of the IMA group and the traffic iscontinuous, a link failure affects the traffic. If you are not using the entirebandwidth or the traffic is not intensive, a link failure does not necessarily affectthe traffic.

The maximum allowed number for each IMA group is 8 exchange terminals. TheIMA group must be created at both ends of the physical links.

Note

IMA functionality is not supported over fractional E1/T1/JT1 lines.

Before you start

You must have configured the PDH exchange terminals (PETs) before you createan IMA group. For the instructions, see Configuring PDH for ATM transport.

The PETs to be combined to an IMA group must belong to the same NIP1functional unit. Check which functional unit a PET belongs to with the USIcommand.



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Creating IMA group

Each PET is identified by its exchange terminal index, which is a system-wideunique numerical value. In addition, the system assigns a link ID to each PET.This link ID is unique in the IMA group.

One of the physical links functions as the Timing Reference Link (TRL) of theIMA group, which is identified by its link ID PET index. The system assigns theTRL to the IMA group.

Steps

1. Create IMA group (YBC)

ZYBC:[<IMA group id>] | <system select> def:[<exchange terminal type> | PET def],<exchangeterminal index>...:<minimum number of links>;

Further information

You can add more PETs later on to the group with the YBA command. Themaximum number of PETs in an IMA group is 8.

2. Create phyTTP for the IMA group

See the instructions in Creating phyTTP.

Further information

You can interrogate IMA groups with the YBI command, modify with the YBMcommand, and delete with the YBD command.

It is possible to remove exchange terminals from IMA group with the YBRcommand. Note that the capacity of the IMA group, that is, the system requiresthe total number of links, must equal or be greater than the used capacity of theATM interface.

Adding/removing links automatically affects the bandwidth of the access profileof the ATM interface.

Example 2. Creating IMA group

1. Create an IMA group using the IMA group ID selected by the system.

The type of exchange terminal is PET by default. The IMA groupcombines PDH exchange terminals 0, 5 and 14. The minimum requirednumber of links in the group is 2.

ZYBC::,0&5&14:2;




2. Add the exchange terminal 12 to the IMA group 3.

ZYBA:3:12;

3. Create phyTTP for the IMA group.

ZYDC:2:IMA=3;



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Creating IMA group

14 Configuring SDH for ATM transportPurpose

This procedure describes how to configure the SDH/ATM interface and modifythe SDH exchange terminal (SET) configuration. You can define how thetransmission capacity is divided, and change the threshold levels for perfomancemonitoring to meet the expected quality of the transmission network.

Before you start

You must create the functional unit description for the SETs. For the instructions,see Creating and attaching functional unit description in Hardware ConfigurationManagement.

Steps

1. Interrogate the SET (YAI)

With the following command you can find out the current exchangeterminal configuration.

ZYAI:<SET>,<SET index>;

2. Configure the SET (YAN)

Note

This step is only necessary if you want to modify the default settings.

Note

When VC mapping is changed, the affected higher and lower order paths get theirdefault values.



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Configuring SDH for ATM transport

Note that for the NIS1 and NIS1P units only one loopback status(diagnostic or line) can be on at a time.

Currently the SES BIP, SD BER, and SF BER parameters are not used forthe higher or lower order paths. The SES BIP threshold for the higher orderpaths is the same as the one used for the multiplex section of the SET.

From the ATM traffic point of view the mapping mode parameter valuesVC3VC11, VC3VC12, VC4VC11, and VC4VC12, and the payloadmapping mode parameter values ASYNCH, BITSYCH and BYTESYNCHare irrelevant.

ZYAN:<SDH exchange terminal index>...,[<higher orderpath number>|<higher order path number>,<lower orderpath number>]:[<SES BIP threshold>]:[<SD BERthreshold>]:[<SF BER threshold>]:[DIA=(ON|OFF)|LINE=(ON|OFF)|LASER=(ON|OFF)]...:[VC3|VC4|VC3VC11|VC3VC12|VC4VC11|VC4VC12]:[SDH|ATMML|SONET]:[ASYNCH|BITSYNCH|BYTESYCH];

3. Set the SDH trace (YAS)

You can set the SDH trace already during integration or later on, ifnecessary. The SDH trace trail must be configured identically to both thetrails related to a specific phyTTP (logical path) in a protection group.When you configure a trace for a trail that is part of a protection group, thesystem automatically applies the changes also to the other trail of the pairand sends a notification on this.

Note

Trace types EXPPATH and EXPREG are not currently supported.

ZYAS:<SDH exchange terminal index>,[<higher orderpath number>|<higher order path number>,<lower orderpath number>]:(OUTPATH|EXPPATH|OUTREG|EXPREG),(RESET|SET1|SET16|SET64),<trace value>;

For more information on the trails, see Creating SDH protection group.

4. Create SDH protection group, if necessary




If you want to secure the traffic even when a line fails, you need to createan SDH protection group. Refer to the instructions in Creating SDHprotection group.

5. Create phyTTP

Refer to the instructions in Creating PhyTTP.

Further information

You can interrogate the incoming SDH traces with the YAT command.

Example 3. Configuring SDH for ATM transport

1. Modify the SES BIP threshold of the SET 1 to 2300 frames per second. Setthe VC mapping to VC-3.

ZYAN:1:2300::::VC3;

2. Modify the SES BIP threshold of the SET 2 to 2300 frames per seconds.Set the VC mapping to VC-3

ZYAN:2:2300::::VC3;

3. Modify the outgoing path trace of the VC path 2 of SET 1. Use 16 byteformat.

ZYAS:1,2:OUTPATH,SET16,"OUT PATH TRACE";

4. Modify the outgoing path trace of the VC path 2 of SET 2. Use 16 byteformat.

ZYAS:2,2:OUTPATH,SET16,"OUT PATH TRACE";

5. Create the SDH protection group from SET 1 and SET 2 with protectiongroup id 4.

ZYWC:4:1,2;

6. Create phyTTP with id 10 for the path 2 of the protection group 4.

ZYDC:10:PROTGROUP=4:2:;



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15 Creating SDH protection groupPurpose

You can create a protection group which is formed by two SDH exchangeterminals (SET). Multiplex Section trail linear protection is used to protect asingle multiplex section trail by replacing a working MS trail if it fails or if theperformance falls below required level. The supported protection protocols arelinear, bi-directional Multiplex Section Protection (MSP) 1+1 compatible with 1:n protocol and linear, bi-directional Automatic Protection Switching (APS) 1+1.Both of the protocols can be used either in revertive or in non-revertive mode.

The SDH trace trail must be configured identically to both trails related to aspecific logical path in a protection group. If this is not the case, the systemprevents the protection group creation.

Steps

1. Create the SDH protection group (YWC)

ZYWC:[<protection group id>|<system select> def],[<protection switching mode>|NONREV def],[<protocolvariant>|MSP def]:<Working section SDH exchangeterminal index>,<Protection section SDH exchangeterminal index>:[<wait to restore time>|300 secondsdef];

The system will ensure that both trails of a pair must be configuredidentically in a protection group.

2. Create the phyTTP, if necessary

If the protected SDH interfaces are for ATM traffic transport, you need tocreate a phyTTP.

See the instructions for creating the physical layer Trail Termination Pointin Creating phyTTP.



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Creating SDH protection group

Expected outcome

The system generates a 0101 SDH PROTECTION SWITCHING EXECUTEDnotice if the protection switch operation succeeds.

Unexpected outcome

The system generates a 3183 SDH PROTECTION SWITCHING FAILED alarmif the protection switch operation fails.

If the far end has not been configured to support the correct SONET APSconfiguration, the system generates a 3307 MISMATCH IN SONET APSCONFIGURATIO alarm.

Further information

You can interrogate the protection group configuration and the protectionswitching status information with the YWI command, modify the configurationwith the YWM command and delete the configuration with the YWD command.Note that a protection group cannot be deleted if a phyTTP has been created forit.

Example 4. Configuring the SDH protection group with default protectionprotocol parameter values

1. Create a protection group of SET 7 (working section) of NIS1P-1 and SET4 (protection section) of NIS1P-0 with protection group ID 3.

Default non-revertive mode and MSP 1+1 variant are used.

ZYWC:3,,:7,4;

2. Create a phyTTP with id 3 for the path 1 of the protection group 3.


Example 5. Configuring the SDH protection group with SONET APSvariant of the protection protocol and with revertive mode

1. Create a protection group of SET 6 (working section) of NIS1P-1 and SET3 (protection section) of NIS1P-0 with protection group ID 4.

Revertive mode and APS 1+1 variant are used.

Default of wait to restore time is used.

ZYWC:4,REV,APS:6,3;




2. Create phyTTP with id 4 for the path 1 of the protection group 4.




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16 Creating phyTTPPurpose

The Physical layer Trail Termination Point (phyTTP) is configured between thephysical layer and the ATM layer. The phyTTP ID is used when creating theATM interface.

You can create a phyTTP for a single PET, an IMA group, a single SDH VC path,or a VC path of an SDH protection group.

Note

You cannot create a phyTTP for a single SDH VC path of a 2N redundantnetwork interface unit. The phyTTP for a 2N redundant unit must be created forthe VC path of the SDH protection group that has been created for the unit.

Before you start

You must configure the PDH or SDH interfaces (PET, SET, an IMA group, asingle SDH VC path or a VC path of an SDH protection group) before you cancreate the phyTTP for them. For configuration instructions, see Configuring PDHfor ATM transport and Configuring SDH for ATM transport.

If you need to interrogate the phyTTP configuration or the operational state of thephyTTP, use the YDI command.

Steps

1. Create a physical layer Trail Termination Point (YDC)

If you created an IMA group, give the ID of the IMA group for the IMAparameter. If you created an SDH protection group, give the ID of theprotection group for the PROTGROUP parameter.



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Creating phyTTP

Note

The MML command for creating the phyTTP includes a parameter, payloadtype, for separating ATM traffic from PPP traffic. However, only ATM traffic issupported in this release.

ZYDC:<phyTTP>:(PET=<PDH exchange terminal>|IMA=<IMAgroup>|SET= <SDH exchange terminal>|PROTGROUP=<protection group>):[<VC path number>|<default>def]:[ATM def|PPP],[ON def|OFF];

Further information

You can delete a phyTTP with the YDD command. After the deletion its physicalresources are free to be used again, for example, you can add PET to an existingIMA group or you can protect SET by creating a protection group. On the otherhand, IMA/protection group can be deleted if there is no phyTTP related to it.The phyTTP cannot be deleted if it is used by the upper layer, that is, if there is anATM interface created on it. You can use the YDI command to check whether thephyTTP is in use or not.

Example 6. Creating a phyTTP for a SET

Create a phyTTP with ID 1 of the SET with index 0 and VC path number 1.

ZYDC:1:SET=0:1:;

Example 7. Creating a phyTTP for a PET

Create a phyTTP with ID 1 of the PET with index 10.

ZYDC:1:PET=10;

Example 8. Creating a phyTTP for an IMA group

Create a phyTTP with ID 2 of the IMA with index 20.

ZYDC:2:IMA=20;




17 Interface-specific TC measurementshows transmission errors

Description

The interface-specific TC (transmission convergence) measurement measures anATM subnetwork's ability to process and deliver incoming ATM cells. It providesinformation about the amount of traffic between transmission path terminationpoints (E1, T1, J1 and STM-1 interfaces).

Interface-specific TC measurement also reports protocol abnormalities (ATM cellheaders corrupting during transmission) detected on the transmissionconvergence sublayer of the broadband protocol stack.

You can check the interface-specific statistics with the PM Explorer application inNEMU or via the network management system.

Symptoms

The interface-specific TC measurement shows the number of cells received withheader error control (HEC) violation. If the number of discarded cells suddenlyexceeds the normal figures, there are a lot of bit errors in the transmission path.

Recoveryprocedures

Checking discarded cells

Steps

1. Check the discarded cells

Take the path out of use and study the reason for the bit errors.



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Interface-specific TC measurement shows transmission errors

18 STM-1 measurement showstransmission errors

Description

The STM-1 measurement measures a transmission path's ability to provide theagreed quality. If a satisfactory quality is not provided, the transmission pathcannot be used.

The measurement gives information about the SDH interface in general, as wellas information about the STM-1 interface. The information includes errors suchas background block error (BBE), errored second (ES), and severely erroredsecond (SES).

You can check the STM-1 related statistics with the PM Explorer application inNEMU or via the network management system.

Symptoms

The parameters regenerator section SES, multiplex section SES,or path termination section SES appear when measuring STM-1interfaces.

Recoveryprocedures

Checking SES parameters

Steps

1. Check SES parameters

The parameters regenerator section SES, multiplex sectionSES, or path termination section SES do not usually appear ifthe transmission path functions normally. If SES values exceed the allowedlevel, all traffic in the transmission path is discarded, that is, no cells arecarried to the ATM layer.



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STM-1 measurement shows transmission errors

If the situation is not normalised, take the transmission path out of use asno traffic can be transmitted via this path.




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ATM over PDH

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SDH supervision

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Related Topics


Descriptions

SDH transmission

Creating phyTTP

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Physical layer Trail Termination Point

Interface-specific TC measurement showstransmission errors

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STM-1 measurement shows transmission errors

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Measuring interface-specific TC

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SDH transmission




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