MAGDA2 - 6/12/2002

Distributed diagnosis of telecomunications networks

Armen Aghasaryan

MAGDA2 - 6/12/2002 — 2 All rights reserved © 2002, Alcatel

diagnoser diagnoser

the diagnosis problem : definition

telecommunications network

supervision

• Fault propagation – causality • Alarm interleaving – concurrency• Distributed processing

MAGDA2 - 6/12/2002 — 3 All rights reserved © 2002, Alcatel

the diagnosis problem : SDH example

AD

M

AD

M

alarm TFnotification State_Change()

alarm LOSnotification State_Change()+ vertical propagation

alarm TFalarm LOS+ vertical propagation

OpticalSPITTPBdir OpticalSPITTPBdir

ALS

MAGDA2 - 6/12/2002 — 4 All rights reserved © 2002, Alcatel

fault model-based approach

Managed Objects (MIB)

Topology / Connections Device (NE) specificities

Diagnosisprocess

alarms

FaultModel

diagnosed fault scenario(s)

Experts knowledge

Can be automated

MAGDA2 - 6/12/2002 — 5 All rights reserved © 2002, Alcatel

fault model-based approach: model inversion

> Fault model replicates the fault behaviour of the network• initial faults, their propagation, and the observed alarms

> Diagnosis algorithms inverse the model!• distributed dynamic programming methods

> Uncertainties in the behaviour• probabilities can be introduced in the model

Diagnosisprocess

observed alarms

Faultmodel

diagnosed fault scenario(s)

fault scenario generatedalarms

MAGDA2 - 6/12/2002 — 6 All rights reserved © 2002, Alcatel

fault model-based approach : methodology

> Structural model (ITU-T…)

SDH Ring

• physical network topology• network elements

• connections model

> Behavioural model

Montrouge

MAGDA2 - 6/12/2002 — 7 All rights reserved © 2002, Alcatel

fault model-based approach : behavioural model

> Elementary Sequence Diagram (UML extension)• pre-condition: attributes, received messages• action: sending messages, changing attribute values• post-condition: attributes, sent messages

Managed Object

MAGDA2 - 6/12/2002 — 8 All rights reserved © 2002, Alcatel

fault model-based approach : behavioural modeldetection of the emission interruption and respective actions

detection of the emission interruption and respective actions

detection of the absence of signal caused by the distant device

detection of the absence of signal caused by the distant device

automatic laser switchmechanism

automatic laser switchmechanism

actions in case of the absence of signal

actions in case of the absence of signal

MAGDA2 - 6/12/2002 — 9 All rights reserved © 2002, Alcatel

fault model-based approach : correlation tree

St Ouen Aubervilliers

Montrouge Gentilly

TFLOS

TFLOS

MS-AIS

MS-AIS

disabled AU-AISAU-AIS

AU-AISAU-AIS

disableddisabled

AU-AIS AU-AIS disabled