01_Why_SDH

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Synchronous Digital HierarchySynchronous Digital HierarchySynchronous Digital HierarchySynchronous Digital Hierarchy

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Migration of SDHMigration of SDH

WHY IS SDH

ContentContent

SDH — 2 All rights reserved © 2004, Alcatel

Network Role of SDH NE

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HistoricalHistorical

70s SYNTRAN

The fixed allocation of the bytes inside the frame

drasticallysimplifies the direct access to the tributaries.Problems due to the phase shift.


The problem due to the phase shift has been solved bymeans of the pointer mechanism.

90s SDH

Derived from SONET. First definition in CCITT (June1988) with the issue of Rec. G707, 708, 709. Between 89and 92 other Recs. have been issued and works still inprogress to define all the aspects both in ITU-T and ETSI.

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Migration of SDHMigration of SDH1st SDH

ADM-Add-Drop Multiplexer

WBDCS-Wide Band-DCS

BBDCS-Broad Band DCS

Next-Gen SDH

MSPP –

Multiservice Provisioning Platform

Core Optical Switching System

Third-Gen SDHMSPP –

Multiservice Provisioning PlatformMSSP –

Multiservice Switching PlatformMSTP –

Multiservice Transport Platform

MSA – Multiservice AccessCore Optical Switching System


MatrixSDH/PDH

MatrixSDH/PDH

Trib

Aggr.W

Aggr.E

Trib

19901990

Port

Port

Port

PortMatrixSDH/PDH

MatrixSDH/PDH

1998~20031998~2003

Port

Port

Port

PortMatrixSDH PDH

Data

MatrixSDH PDH

Data

2004 ~2004 ~

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> Services: mainly PSTN, fewswitched data services, few

leased lines (semipermanent).> Rigid network infrastructure

based on point-to-pointconnections between exchanges(NB-EX), PABX and networkterminations.

Characteristics of the past networksCharacteristics of the past networks

NB-EX

NB-EX

PDHINFRASTRUCTUR

E

NB-EX

PABXLEASED LINE


>

network very inflexible.> Dedicated transmission

networks for each type ofservice.

> Very poor filling rate of thepotential available bandwidth

> Only Supervisory functionalities(SCADA systems)

> Three different standards (USA,Europe, Japan) and only forlower bitrates.

NB-EX

LEASED LINE2,4 ...64 KB/S

NB-EX

PABX

PABX

NB-EX: Narrow Band Exchange

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i d t h

e n t s

High

Self-Navi atin

FTP Transfer

Web-basedApps

E-mail with

VideoConferencin

g

StreamingVideo

Not All Applications Were Created EqualNot All Applications Were Created Equal


B a n d

R e q u i r e

Latency SensitivityLow

Field-drivenApps

Client-ServerApps

Appsattachments

StreamingAudio Voice

MedicalTelemetry

Text E-mail

TransactionProcessing

High

Low

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Services

Voice & LL

DSL

2/3G Mobile

BroadcastDi ital

Convergent DataConvergent Data--Aware Transport Infrastructure forAware Transport Infrastructure for

Service Differentiation in the MetroService Differentiation in the Metro

Metro Access2.5G

Alcatel Optical MetroMulti-Service Transport and Aggregation

1696 Metro Span

1692 MSE

1696 MSC

Metro SpanWDM

TDM

METRO ACCESS> Differentiation of Access Interfaces

and Class of Services> Circuit & Packet Traffic Aggregation


Video/VoD

HS InternetAccess

Metro Ethernet

L2 VPNs

Data Storage

SAN

Metro Core10G

Metro Access2.5G

Multi-Service CPE/SDH Alcatel Data-Aware Optical Transport

METRO CORE> Efficient Transport of AggregatedTraffic over SDH/WDM towards theOptical Core

1642 EM

1640 FOX

1662 SMC1660 SM

1670 SM

1650 SMC

EthernetATM

TransparentFC/ESCON

OMSNNG-SDH

Optical CoreLH-WDM & OXC

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Current Status of the Transmission EnvironmentCurrent Status of the Transmission Environment

Nowadays, Operators have to face new important aspects relatedto Transmission Networks:

Massive introduction of new telecommunication Servicesincluding broadband (video, digital data, private and virtual privatenetworks services, other future un-forecasted services)


Full utilization of fiber optics, both in backbone and accessnetworks

Need to manage the network as a hole even if built up with differentmanufactures (Multi-Vendor environment)

Competition in deregulated market for telecommunication servicesprovision (Multi-Operator environment)

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Service PeculiaritiesService Peculiarities

Variety of service demand

Temporary/occasional connections (exhibitions, fairs,conventions)

Periodical traffic (seasonal, daily/nightly traffic)

Difficult to make forecasts


Bandwidth requirements Geographical distribution

Severe requirements on service availability

Need to assure the Quality of Service (QoS) throughperformance monitoring and validation

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MultiMulti--Vendor EnvironmentVendor Environment

SNMS SNMS SNMS

NMS I

> Each Vendor has its ownNetwork Management System(NMS)


SNMS : SUBNETWORK MANAGEMENT SYSTEMNMS I : NETWORK MANAGEMENT SYSTEM INTEGRATOR

VENDORSUBNETWORK

VENDORSUBNETWORK

ALCATELSUBNETWORK

> Operator needs to have anintegration layer where tomanage the network as a singleentity.

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MultiMulti--Operator EnvironmentOperator Environment

NMS NMS NMS

> In the deregulated market,Operators are becomingmore customer focused

> customerownership?becomes crucialregardless of the customer


OPERATORDOMAIN OPERATORDOMAIN OPERATORDOMAIN

CPE CPE

CPE: CUSTOMER PREMISES EQUIPMENT

location

> Operators will take up theend-to-end responsibility forthe traffic, even whencrossing multiple otherOperators domains

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Consequences 1/2Consequences 1/2

The Operators have to build transmission networks

Flexible in order to: Satisfy pre-programmed and unexpected traffic requests Be able to introduce services, whenever and wherever they

are re uested in a scaleable wa and without traffic


interruption.

Survivable (traffic recovery for nodes/links failures) inorder to prevent:

Failures in telecommunication networks Loss of income due to the lack of service provision

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Consequences 2/2Consequences 2/2

Manageable in order to:

Assure flexibility and survivability(network construction and reconfiguration)

Guarantee the QoS to the customer


per ormance mon tor ng an va at on

Optimise field maintenance staff and spares stocks

Open to the interconnection with other Network Domains inorder to catch opportunities in a multi-Operator and/or multi-Vendor environment

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Why SDH?Why SDH?

The SDH fulfills the requirements of future transmissionnetworks:

Worldwide standard which allows multivendor compatibility Standardized also for high bitrates Compatible with existing PDH and future ATM networks


ore ex ty an g er qua ty ava a ty, secur tythrough SW-network management and maintenance

Easy add and drop of all tributaries Reduced equipment and personal cost

It an opportunity for operator to rethink network strategies and

gain competitive advantage

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Synchronous Digital Hierarchy

PDH/SDH signal levelsPDH/SDH signal levels

U.S.Europa Japan

Plesiochronous Digital Hierarchy

STM-16: 2488.320 Mb/s

STM-4: 622.080 Mb/s

x4

STM-64: 9953.280 Mb/s

x4

G707


565 Mb/s

140 Mb/s

x4

34 Mb/s

8 Mb/s

x4

x4

2 Mb/s

x4

274 Mb/s

x6

x7

400 Mb/s

100 Mb/s

x4

x3

x5

x4

1.5 Mb/s

45 Mb/s 32 Mb/s

6 Mb/s

x84 or x63

1.5 or2 Mb/s

x21

1.5 or2 Mb/s

x3

34 or45 Mb/s

x1

140 Mb/s

x4

STM-1: 155.520 Mb/s

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STMSTM--1 frame structure1 frame structure

Section Overhead

RSOH

270 columns (bytes)

9 261

1

Basic Frame

The basic frame adopted bythe ITU-T, called STM1, isstructured in bytes and hasthe folllowing characteriscitcs:

LENGTH : 2430 bytesDURATION : 125 µs


AU-Pointer

Section Overhead

MSOH

45

9

9 r o w

s

125 µs

Payload

: . sPAYLOAD : 2340 bytes

(i.e. 149.760 Mb/s)

Given the large number ofbytes in a frame, the frame isrepresented for praticalreasons in the form of arectangle of bytes transmittedfrom the top left down to the

bottom right, as when readingwords on a page. Each byterepresent 64 Kb/s.

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STMSTM--N frameN frame

Section Overhead

RSOH

270 x N columns (bytes)

9 x N 261 x N

1


AU-Pointer

Section Overhead

MSOH

3

4

5

9

9 r o w s

125 µs

Payload

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SDH standardsSDH standards

Standard of the SDH is based on the following fundamentalrules:

8 KHz frame frequency, i.e. 125 us frame duration, is usedthroughout the multiplexing hierarchy.

Byte-interleaved multiplexing (as in the primary multiplex signals) isused throu hout all multi lexin sta es.


Interface for plesiochronous signals of all standard bitrates from 2(1.5) to 140 Mbit/s.

Additional capacity to all tributary signals is provided for the purposesof network handling, maintenance and management.

The STM-1 level at 155 Mbit/s is in general the interface between the

network nodes and the transmission links.

Transmission systems must operate at bitrates which are an integermultiple of the 155 Mbit/s STM-1 bitrate.

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SDH PrinciplesSDH Principles

Mapping :

Overheads :

of PDH (and other) signals into SDH containers,containers have payload independent fixed sizes, byteoriented structure, frame frequency of all containers : 8

KHz, each byte represents a 64 Kbit/s capacity.

added to each tributary signal and to the STM-1 signal,for network management functions (operation,


Pointers :

Multiplexing :

, .

for indication of frame start bytes and simpledemultiplexing function.

by byte interleaving at all levels, frame duration at alllevels: 125 µs.

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SDH Multiplex structure (1)SDH Multiplex structure (1)

AUGSTM-1x1 x1

AU-4 VC-4 C-4

x1

TU-3TUG-3

x3x3

x7

VC-3

SOH PTR POH POHPTR

139 264 Kbit/s

STM-4

STM-16


ESTI SUBSET

POINTER PROCESSING

MULTIPLEXING

ALIGNING

MAPPING

AU Administrative UnitAUG Administrative Unit GroupC ContainerSTM Synchronous Trnsport ModulTU Tributary UnitTUG Tributary Unit GroupVC Virtual ContainerPOH Path OverheadSOH Section OverheadPTR Pointer

Legenda

VC-3AU-3

x1

TU-2 VC-2

C-3

x3

TUG-2

VC-12

TU-11x4

TU-12

VC-11

C-2

x7

C-12

C-11

44 736 Kbit/s

34 368 Kbit/s

2048 Kbit/s

1544 Kbit/s

6312 Kbit/s

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SDH multiplexingSDH multiplexing

The container C is made up with:

Tributary bits Fixed stuffing bits

Justification bits with the pertaining justification signalling bits.

The virtual container VC

It is made up with:


conta ner

A byte called Path Overhead (POH) which occupies the first position of thestructure.

The POH contains auxiliary information to check the quality of the end - to -endpath.

The tributary unit is made up with:

A virtual container A tributary unit overhead (TUOH or PTR) located in a fixed position inside the

higher order structure. The PTR contains the information concerning the position ofthe VCinside the higher older structure.

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The ICE of transmissionThe ICE of transmission

STM-1


STM-1

ICE Inter-City-Express

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A container is suitable for therate of the signal and for thestructure of the synchronousframe. It is an entity for which

capacity is defined in order toensure transmission of the ratesdefined by the plesiochronoushierarchy.

Container: CnContainer: Cn

139264 Kb/s

44736 Kb/sn = 4


n = INDEX OF RELEVANTCONTAINER

Example :

THE PLESIOCHRONOUS SIGNALAT 140 MB/S IS INSERTED INTO ACONTAINER OF INDEX 4 : C4

15444 Kb/s

2048 Kb/s

34368 Kb/s

n = 11

Cnn = 3

n = 3

n = 12

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A Path Overhead (POH) isassociated with the VirtualContainer.

Virtual Container: VC (1)Virtual Container: VC (1)

Cn

POH


That additional rate is reserved

for operation of the container towhich it attached.The VC is the entity managedby the SDH network.

VCn

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VC-4 C-4 139 264 Kbit/s

VC-3

Higher Order VC Lorder Order VC

Virtual Container: VC (2)Virtual Container: VC (2)

Lower order VCs aremade up solely of acontainer and the

associated POH Higher order VCs

can contain lowerorder VCs


INSERTION OF POH

VC-3 44 736 Kbit/s

34 368 Kbit/s

VC-2

C-3

2048 Kbit/sVC-12

1544 Kbit/sVC-11

C-2

C-12

C-11

6312 Kbit/s

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Tributary unit: TUTributary unit: TU

VC-4 C-4 139 264 Kbit/s

VC-3 44 736 Kbit/s

34 368 Kbit/sC-3

VC-3

Pointer

TU-3

The tributary unit ismade up of a lowerorder virtual

container and of apointer (PTR). Thepointer indicates thelocation of the VCnwith the frame


VCn + POINTER

2048 Kbit/s

1544 Kbit/s

C-2

C-12

C-11

6312 Kbit/s

Pointer

TU-2

TU-12

TU-11

VC-2

VC-12

VC-11

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Tributary unit group: TUGTributary unit group: TUG

VC-4 C-4 139 264 Kbit/s

VC-3TU-3TUG-3

x3x1

The tributary unit

group is made up ofa homogeneous setof tributary units(TU1, TU2 or TU3)which are multiplexedwith each other.


VC-344 736 Kbit/s

34 368 Kbit/sC-3

2048 Kbit/s

1544 Kbit/s

C-2

C-12

C-11

6312 Kbit/sTU-2

TU-12

VC-2

VC-12

TUG-2

x7

VC-11

x1

x3

x4

x7

TU-11

i.e. The TUG2 pools

either 4 x TU11 or 3 xTU12 or 1 x TU2.

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Administrative unit: AUnAdministrative unit: AUn

Pointer

VC-4 C-4 139 264 Kbit/s

ATM

VC-3TU-3TUG-3

x3

x1

x7

Higher Order VC Lorder Order VC

AU-4

The administrativeunit is made up ofhigher order VCs and

of an administrativeunit pointer whichvalue indicates thelocation of the start ofthe virtual containerwithin thetransmission frame


Pointer

VC-3 44 736 Kbit/s34 368 Kbit/sC-3

2048 Kbit/s

1544 Kbit/s

C-2

C-12

C-11

6312 Kbit/sTU-2

TU-12

VC-2

VC-12

TUG-2

x7

VC-11

x1

x3

x4

AU-3

TU-11High Rate

MultiplexingLow Rate

Multiplexing

VC-X+ POINTER

INSERTION OF POH

used.

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Overhead bytesOverhead bytes

Definition of path and sectionDefinition of path and section

Typical SDH links can be divided into three parts:

Path TerminalLine TerminalLine TerminalPath Terminal

Regenerator Regenerator


Regeneratorsection

Multiplexer section

Path

Plesiohronous path

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Overhead Bytes: TypesOverhead Bytes: Types

Overhead bytes are divided into:

Bytes POH of virtual container VC

They are used to check the service of the end-to-endpath.


Bytes SOH of the STM-N frame, associated withline end section levels.

They are necessary for maintenance and protectionmechanism.

Further they are divided into two subgroup:

• RSOH (Regenerator Section Overhead)• MSOH (Multiplex Section Overhead)

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Regenerator Section OverheadRegenerator Section Overhead

9

RSOH

RSOH contains the data requiredto transfer the payload from oneequipment to the next in the SDHNetwork. RSOH is terminated by

all the SDH Network elements.


B1 ∆ ∆ E1 ∆ X F1 N N

D1 ∆ ∆ D2 ∆ X D3 X X

A1, A2 Frame alignment

JO Reg. Section Trace(former: identifier C1)

B1 RS bit error monitoring (BIP-8)E1 RS orderwire channelF1 64 Kb/s User channel

(identification of a failed section)D1-D3 192 Kbit/s data communication

channel (DCC) for TMN

N National useX For future standardization∆∆∆∆ Media dependent bytes

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Multiplex Section OverheadMultiplex Section Overhead

MSOH

9

The MSOH is terminated by all SDHelements, except regenerators.


B2 B2 B2 K1* X X K2* X X

D4* X X D5* X X D6* X X

D7* X X D8* X X D9* X X

D10* X X D11* X X D12* X X

S1 M1 E2* N N

B2 Bit error monitoring (BIP-24)

K1,K2 Automatic protection switchsignalling - K2 b6-b8 MS-RDI

(FERF)D4-D12 576 Kbit/s data communication

channel for TMNZ1,Z2 For future standardizationE2 MS orderwire channelS1 Synchronization status

M1 MS (FEBE of BIP-24) - Far endblock errorsN National useX For future standardization

5

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J1

VCVC--4/3 Path Overhead4/3 Path Overhead

VC-4POH


B3

C2

G1

F2

H4

F3

K3

N1

J1 Path trace Check of path connection from formation

of the VCB3 Path bit error monitoring (BIP-8) Measure of quality of the pathC2 Signal label It indicates wheter or not the VC carries

traffic and the type of traffic.G1 Path status (REI and RDI) REI (Remote Error Indication) indicates the

number of errors detected by B3.F2, F3 Data channel 64 Kbit/s RDI (Remote Defect Indic.) indicates failure

or not of the far end.H4 Multiframe indicator Alignment for indicating the locations of

the tributaries signals.K3 APS channel (b1-b4) Used for path protection (APS)N1 Tandem Connection Monitoring Within one operators domain

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VCVC--12 Path Overhead12 Path Overhead

V5 The bytes V5, J2, N2 and K4 areallocated to the VC-2/1 POH using amultiframe structure according to thefigure.

V5

J2


b1,b2 Path bit error monitoring Check the quality of the virtual container VC-1 or VC-2

s1 Path status (REI) Feedback of remote block error datat Remote Failure Indication (RFI) Feedback of persistent remote signal failuresl1-l3 Signal label Indication of payload VC-1 or VC-2 compositions2 Path status (RDI) Feedback of remote signal defects (e.g. AIS)

V 5 b 1 b 2 s1 t l 1 l 2 l 3 s2=

J2 =

N 2 =

K4 =

VC lower order Path Trace(it checks the path connection from formation of VC to the other end of the

path)

It provides a Tandem Connection Monitoring (TCM) function

(bits 1-4) used for APS signalling for protection at the lower order path

N2

K4

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SDH elements (1)SDH elements (1)

Definitions of SDH network elements according G.782

TributariesG.703

STM-N

STM-N

-

Multiplex type I

Multi lex t e II


M,

M>N

STM-M STM-M,M>N

STM-N STM-N

G.703, STM-N

Multiplex type III

Multiplex type IV

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SDH elements (2)SDH elements (2)

Crossconnect type I

G.703 HPCmatrix

-

Crossconnect type III

Definitions of SDH network elements according G.782


G.703

STM-NCrossconnect type II

-

G.703 LPCmatrix

(VC-3/2/1)STM-N

HPC + LPCmatrix(VC-4+

VC-3/2/1)

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SDH configurationsSDH configurations

G.782MUX I.2

G.782MUXII.2

Terminal Multiplexer

Add Drop Multiplexer

Re enerator like

ADM

TRIBS ADMSTM-NAGGSP

STM-N

AGGS P

STM-N

AGGSP

TRIBS

G.782

MUXIII.1

G.782MUXIII.2

G.782


HUB Node

(NO THROUGH TIMING,

MS TERMINATION)

Cross-Connect like

(RESTRICTION ON CONNECTIVITY,CONNECTION SUPERVISION ANDNETWORK PROTECTION)

-AGGS P

-AGGSP

ADMP

STM-NAGGSP

STM-N

TRIBS

STM-NAGGS

ADM STM-NAGGS

STM-NAGGS

TRIBS

MUXIII.1

G.782MUXIII.2

SUBEQUIPPED

G.782MUXIII.2

G.782C-C III

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SDH applicationsSDH applications

Point to Point

Linear drop/insert ADMP

ADMP

R

ADMP

RP

R

PADM


Shelf-healing ring

ADM

ADM

R

ADM

ADM

P

P

P

P

P

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Q & AQ & A


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01_Why_SDH