NBP/RTTC-MYSORE

NIRANJAN Regional Telecom Training Center MYSORE

SDH Framing StructureSDH Framing Structure

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PP

OO

HH

TUG-3TUG-3

TUG-3TUG-3

TUG-2TUG-2 TUG-2TUG-2

TU-12TU-12

TU-12TU-12

2 Mbit/s2 Mbit/s

Stuff

C-12C-12

Overhead (PDH)

VC-12VC-12

Pointer (PTR)

TU-12TU-12

TU-12TU-12

TU-12TU-12

TU-12TU-12

TUG-2TUG-2 TUG-2TUG-2 TUG-2TUG-2 TUG-2TUG-2 TUG-2TUG-2TUG-3TUG-3

VC-4VC-4

VC-4VC-4

MSOHMSOH

AU PointerAU PointerVC-4VC-4

SDH Framing Structure

RSOHRSOH

AU-4AU-4STM-1STM-1

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SDH ALARMS

• LOS : When NE is unable to receive signal from other NE , due to fiber break , Tx failure of other NE,etc .It triggers Loss Of Signal

• LOS is Physical Layer Alarm• There is no byte in SDH frame to indicate LOS. Its the

transreceiver (SFP) which detects the in coming signal. • If no light coming to SFP it gives LOS to processor or the

controlling device.

Also when u get BER of orde 1 in 1000 results in LOS

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LOS-Loss Of SignalAIS-Alarm Indication Signal

RDI-Remote Defect Indication

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Probable Causes

ALARM PROBABLE CAUSE1) STM -N Port loss of signal OF cable break

 Rx optical power beyond thrushhold limit (local eqpt)

 TX forced off (Forced Laser Off at distant end)

  Distant ADM/TM/REG module fault

  Distant end power failure

  Local RX faulty

   

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SDH ALARMS

• LOF : Assuming that signal is present . • Next job is to identify STM-1 frame by means

of Nx 6 bytes FAW ( 3 bytes of A1 and 3bytesA2 bytes of RSOH) .

• Else it triggers Loss Of Frame

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LOF-Loss Of FrameAIS-Alarm Indication Signal

RDI-Remote Defect Indication

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THE NEXT STEP IS TO FIND WHERE THE VC-4S ARE LOCATED RELATIVE TO THE FAW.

THIS IS ESTABLISHED BY READING THE ADMIN UNIT (AU) POINTER TO LOCATE THE J1 BYTE IN THE VC-4 POH.

IF A SENSIBLE POINTER CANNOT BE FOUND, A LOSS OF POINTER (LOP) ALARM IS RAISED AT THE AU LEVEL. THIS IS USUALLY REFERRED TO AS AN AU-LOP,

AU-LOP

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LOP-Loss Of Pointer

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TU-LOP

The next step is to locate and read the Tributary Unit (TU) pointer for the specified TU. If a sensible pointer cannot be found, then a LOP alarm is raised at the TU level

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LOP-Loss Of Pointer

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AIS (Alarm Indication Signal)LOS, LOF, and LOP alarms will render the whole signal unusable. In this case, the missing or corrupted signal is replaced by an AIS consisting of continuous binary 1s. This will produce AIS alarms on all equipment downstream of the fault

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AIS-Alarm Indication SignalRDI-Remote Defect Indication

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AIS-Alarm Indication Signal LOS-Loss Of Signal

RDI-Remote Defect Indication

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AIS-Alarm Indication SignalRDI-Remote Defect Indication

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AIS-Alarm Indication SignalRDI-Remote Defect Indication

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FERF- Far End Reporting Failure RAI-Remote Alarm Indication

The NE detecting the fault also sends an indication to the distant (sending) end that an alarm has been raised. This raises a FERF alarm at the appropriate level at the transmitting NE. Thus, a fault at the MS level will produce an MS-FERF. At the VC-4 level, it will produce a VC-4 FERF on some equipment, HO-FERFs.

Some SDH elements refer to a remote alarm indication at some levels in the hierarchy.

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HO FERF- Far End Reporting Failure

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LO FERF- Far End Reporting Failure

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BIP-Bit Interleaving Parity

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TIM-Trace Identifier MismatchAIS-Alarm Indication Signal

RDI-Remote Defect Indication

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BIP-Bit Interleaving Parity

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EXC-Excessive Bit Error rate( > 10x E-3)

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BIP-Bit Interleaving Parity

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RDI-Remote Defect Indication

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REI-Remote Error Indication

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DEG-Degradation

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UNEQ- UNEQuipped

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TIM-Trace Identifier Mismatch

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BIP-Bit Interleaving Parity

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RDI-Remote Defect Indication

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REI-Remote Error Indication

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DEG-Degradation

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EXC-Excessive Bit Error rate( > 10x E-3)

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PLM-Path Load Mismatch

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TIM-Trace Identifier Mismatch

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RDI-Remote Defect Indication

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REI-Remote Error Indication

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DEG-Degradation

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EXC-Excessive Bit Error rate( > 10x E-3)

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PLM-Path Load Mismatch

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UNEQ- UNEQuipped

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LOM-Loss Of Multi frame

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ERROR MONITORING

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B1 byte is used to check for errors in the RS.B2 byte is used to check for errors in the MS.B3 byte is used to check for errors in the VC-4 path.V5 byte is used to check for errors in the VC-12 path.

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BIP-Bit Interleaving Parity

B1,B2,B3 & B5 bytes are used for Error Detection in specific section and path . This is based upon BIP detection mechanism

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