SDH ALARMS

NBP/RTTC-MYSORE

NIRANJAN Regional Telecom Training Center MYSORE

SDH Framing StructureSDH Framing Structure

NBP/RTTC-MYSORE

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

NBP/RTTC-MYSORE

NBP/RTTC-MYSORE

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

NBP/RTTC-MYSORE

LOS-Loss Of SignalAIS-Alarm Indication Signal

RDI-Remote Defect Indication

NBP/RTTC-MYSORE

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

NBP/RTTC-MYSORE

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

NBP/RTTC-MYSORE

NBP/RTTC-MYSORE

LOF-Loss Of FrameAIS-Alarm Indication Signal


NBP/RTTC-MYSORE

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

NBP/RTTC-MYSORE

NBP/RTTC-MYSORE

LOP-Loss Of Pointer

NBP/RTTC-MYSORE

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

NBP/RTTC-MYSORE

NBP/RTTC-MYSORE

LOP-Loss Of Pointer

NBP/RTTC-MYSORE

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

NBP/RTTC-MYSORE

AIS-Alarm Indication SignalRDI-Remote Defect Indication

NBP/RTTC-MYSORE

AIS-Alarm Indication Signal LOS-Loss Of Signal


NBP/RTTC-MYSORE

AIS-Alarm Indication SignalRDI-Remote Defect Indication

NBP/RTTC-MYSORE

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.

NBP/RTTC-MYSORE

HO FERF- Far End Reporting Failure

NBP/RTTC-MYSORE

LO FERF- Far End Reporting Failure

NBP/RTTC-MYSORE

BIP-Bit Interleaving Parity

NBP/RTTC-MYSORE

TIM-Trace Identifier MismatchAIS-Alarm Indication Signal


NBP/RTTC-MYSORE


NBP/RTTC-MYSORE

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

NBP/RTTC-MYSORE


NBP/RTTC-MYSORE

REI-Remote Error Indication

NBP/RTTC-MYSORE

DEG-Degradation

NBP/RTTC-MYSORE

UNEQ- UNEQuipped

NBP/RTTC-MYSORE

TIM-Trace Identifier Mismatch

NBP/RTTC-MYSORE


NBP/RTTC-MYSORE

DEG-Degradation

NBP/RTTC-MYSORE


NBP/RTTC-MYSORE

PLM-Path Load Mismatch

NBP/RTTC-MYSORE

TIM-Trace Identifier Mismatch

NBP/RTTC-MYSORE


NBP/RTTC-MYSORE

DEG-Degradation

NBP/RTTC-MYSORE


NBP/RTTC-MYSORE

PLM-Path Load Mismatch

NBP/RTTC-MYSORE

UNEQ- UNEQuipped

NBP/RTTC-MYSORE

LOM-Loss Of Multi frame

NBP/RTTC-MYSORE

ERROR MONITORING

NBP/RTTC-MYSORE

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.

NBP/RTTC-MYSORE


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

NBP/RTTC-MYSORE

NBP/RTTC-MYSORE

SDH ALARMS

Technology

Transcript of SDH ALARMS