1 chapter 7 transport networks: technology examples m. pickavet and c. develder

1

CHAPTER 7 Transport Networks:

Technology examples

M. Pickavet and C. Develder

Transport networks:Technology Examples 2

Outline

1. Transport network examples1.1 Belgacom1.2 Telenet1.3 Deutsche Telekom1.4 International network

2. SDH3. WDM

Transport networks:

Technology Examples 3

• Unique telephony operator in Belgium for a long time• Basic services: telephony, leased lines, public data network, etc.

• Since 1998, also competition possible on last monopoly: the telephone service

• Basic fixed telephone services expanded to new services (e.g. mobile telephony, fast Internet, digTV)

• Increase bandwidth down to the customer (xDSL techniques)

Belgacom Network

Transport networks:


TEX

TEX

TEX

TEX

DXCDXC

DXCDXC

DXCDXC

DXCDXC

ADMADM

ADMADM

AD

MA

DM

ADMADM

ADMADM

AD

MA

DM

LEX

LEX LEX

LEX

core transport networkregional transport network regional transport network

LEX

LEX LEX

TEX

TEX

LEX

TEX TEX

Belgacom: switching and transport network

Technology: mainly SDH (+PDH & WDM)

Transport networks:


level 1: COREnetwork

level 2: REGIONALnetwork

ZTCZTC: ZonalTransmissionCenter

LTC

LTC: LocalTransmissionCenter

RING + MESH

RING

Belgacom: transport network architecture

Transport networks:


TEX

core

reg

ion

al

DXCDXC ......mesh

ADMADMring

...

...

ADMADM ADMADM

ring

...

...

Belgacom: Zonal Transmission Center (ZTC)

Transport networks:


ZTC: ZonalTransmissionCenter

international links

Belgacom: CORE network topology


Outline


2. SDH3. WDM

Transport networks:


• origin: reuse of existing coax cable (used for TV distribution by CATV operators)

• now: offer also interactive services (telephony, Internet access, digTV)

upgrade access network construct a backbone network

(switching and transmission)

Telenet Network

Transport networks:


HFCloop

Node

Tree and branch 2-waycoaxial network

Subscriberpremise

Secondary ring

Primary ring

head-end

Switch

Telenet: Topology Concept

Transport networks:


21

3

4

8

5

7

6

MIDDELKERKEROKSEM

KOEKELAREVEURNE

IEPER

ROESELARE

SINT-ELOOIS-WINKEL

WAREGEM

OUDENAARDE

ZOTTEGEM

MELLE

EEKLO

LOKEREN

AALST

SINT-NIKLAAS

DENDERMONDE

BRUSSEGEM

MECHELEN

HOVE

SCHOTEN

STABROEK

PERK

LEUVEN

HERENTHOUT

ZOERSEL BEERSE

OUD-TURNHOUT

GEEL

OVERPELT

MAASEIK

GENK

BERINGEN

TESTELT

SINT-JORIS-WINGE

BILZEN

SINT-TRUIDENWOMMERSOM

DUISBURG

DWORPHERFELINGEN

LENNIKMENEN

BRUGGE

GENT

KORTRIJK

ASSE

HOBOKEN

HASSELT

NOC

Primary ring

Secondary ringHeadend

SwitchNOC

Telenet: Physical Topology

Zie ook www.telenet.be, “Bedrijfsinfo”, “Het Netwerk”

http://www.telenet.be/

Transport networks:


accessmultiplexerin head-end

switch

SDH network connections(not the physical topology)

Telenet: Basic Architecture


Outline


2. SDH3. WDM

Transport networks:


• Unique telephony operator in Germany for a long timecf. Belgacom in Belgium

• For mobile solutions: T-mobilecf. Proximus

• Largest European network operator• Presence in countries: Germany, but also US, UK, eastern Europe

• Some numbers (2006-2007): • Total traffic volume: 2250 Gbit/s• Number of lines:

• broadband: 12 million• narrowband: 39 million

Deutsche Telekom


Deutsche Telekom: physical topology

• 50 core nodes

• Technology: WDM


Deutsche Telekom: logical IP topology

• 63 PoPs

• Hierarchical topology:

•Core:•3 innercore nodes (fully meshed)•6 outercore nodes (dual homed with innercore nodes)

•Regio/metro


Outline


2. SDH3. WDM


International networksM

ap

of

Euro

pean

Netw

ork

Con

nect

ivit

y


International network: Level3

Zie ook www.level3.comTechnology: WDM, SONET, …

http://www.level3.be/


Outline

1. Transport network examples2. Synchronous Digital Hierarchy (SDH)

2.1 Introduction2.2 Main layer structure2.3 Detailed layer structure2.4 Frame structure and synchronisation2.5 Network elements2.6 Network architectures

3. WDM

Transport networks:


• bi-directional transport network technology• multiplexing: TDM (Time Division Multiplexing)

• historically: mainly replacing PDH- based on direct synchronous multiplexing- about 5% of signal structure for ‘overhead’- can accommodate both existing and future signals- can interconnect equipment from multiple vendors

• high bandwidth links (capacities: 155 Mbit/s, 622 Mbit/s, 2.5 Gbit/s and 10 Gbit/s)

• semi-permanent network connections (bitrates: 150 Mbit/s, 49.5 Mbit/s, 6.9 Mbit/s, 2.3 Mbit/s)

• central management (TMN) or distributed control (GMPLS)

• network elements: Digital Cross-Connect (DXC)Add-Drop Multiplexer (ADM)Terminal Multiplexer (TM)

Main features of SDH

Transport networks:


• physical layer: Synchronous Transport Module (STM-N)

• link capacity: STM-1: 155 Mbit/sSTM-4: 622 Mbit/sSTM-16: 2.5 Gbit/sSTM-64: 10 Gbit/s

Physical Layer

Transport networks:


Signals that can be transported by SDH:• PDH: 2, (8,), 34, 140 Mbit/s (Europe)• IP: Internet packets• ATM: Asynchronous Transfer Mode• FDDI: Fiber Distributed Data Interface• etc…

Several network connection types(virtual containers):

• VC-4 (150 Mbit/s)• VC-3 (49.5 Mbit/s)• VC-2 (6.9 Mbit/s)• VC-12 (2.3 Mbit/s)

SDH transport capabilities

STM-N

VC-12

3x

OR

1x

VC-2

OR

1x

7x

VC-3

OR

1x

3x

VC-4

Nx

Transport networks:


SynchronousTransport

Module(SDH)

Line RateMbit/s

SynchronousTransport

Signal(SONET)

-

STM - 1

STM - 4

STM - 16

STM - 64

51.84

155.52

622.08

2488.32

9953.28

STS - 1

STS - 3

STS - 12

STS - 48

STS - 192

SONET: - Synchronous Optical Network- introduced 1985 (USA, Japan)

SDH:- CCITT 1988: SDH and SONET linked- ETSI 1990: SONET part of SDH

SDH versus SONET


Outline



3. WDM

Transport networks:


• VC-4 or Virtual Container-4 link connection • VC-4 link connection capacity: 150 Mbit/s• link capacity in # link connections:

STM-1 ==> 1 x VC-4STM-4 ==> 4 x VC-4STM-16 ==> 16 x VC-4STM-64 ==> 64 x VC-4

4

TDM1 N=4 1 4N=4

fiber (622 Mbit/s)

STM-4 network connection

VC-4 link connection

VC-4 link

Higher Order Path Layer

Transport networks:


VC-4 link

fiber (622 Mbit/s)

1 4N=4 1 4N=4

fiber (622 Mbit/s)

1 4N=4 1 4N=4VC-4 link

networkconnection

VC-4matrix

VC-4 link connection VC-4 link connection

matrixconnection

HOP Network Connection

Transport networks:


63

VC-12

21

VC-2

3

VC-3

VC-12VC-2VC-3 LOP layer

1 4N=4

HOP layer

Physical layer

VC-4 = 63 VC-12VC-4 = 21 VC-2VC-4 = 3 VC-3VC-4 = combination of VC-3, VC-2 and VC-12

Lower Order Path Layer

Transport networks:


VC-12 link

VC-12 networkconnection


VC-12 link


fiber (622 Mbit/s)

N=4 N=4

fiber (622 Mbit/s)

N=4 N=4



VC-4 matrixconnection

fiber (622 Mbit/s)

N=4 N=4

fiber (622 Mbit/s)

N=4 N=4





LOP Network Connection

Transport networks:


• full interconnection of switches with VC-3 network connections• ring topology interconnection of VC-3 ADMs with VC-4 network connections• use physical star topology

VC-3ADM

VC-3ADM

VC-3ADM

VC-3ADM

VC-4DXC

switch switch

switch switch

STM-4links

Exercise

Transport networks:


Physical Layer

Transport networks:


HOP Layer

Transport networks:


LOP Layer

Transport networks:


Circuit Layer

Transport networks:


DXC

HOPor

LOP matrix

tributary ports (to higher layer)

aggregate ports(to lower layer)

ADM

LOP/HOP

HOP/Physical

MUX

Network Elements: MUX / ADM / DXC


Outline



3. WDM

Transport networks:


physical layer

regenerator section layer

multiplex section layer

higher order path layerSDH

transportlayers

Overview

lower order path layer

circuit layer

Transport networks:


• optical fiber• coaxial cable• radio link

electrical

fiber linkphysical la

yer

tcp tcp

optical

Physical Layer

Transport networks:


transfer of bits between two physical points

bitrates: 155 Mbit/s, 622 Mbit/s, 2.5 Gbit/s, 10 Gbit/s

laser transmitter

photodetector receiver

optical fiber

Physical Layer

Transport networks:


regenera

tor

secti

on layer

RS link connection =RS network connection

fiber link connectionphysical la

yer

RS trail

Regenerator Section (RS) Layer

Transport networks:


regeneratorfiber fiber

• signal regeneration• signal monitoring• signaling

Regenerator Section (RS) Layer

Transport networks:


MS link connection MS link connection

MS network connection

MS trail

multiplex

sect

ion layer

cptcp tcp

fiber fiber

RS network connection RS network connectionregenera

tor

sect

ion layer

physical la

yer

Multiplexing Section (MS) Layer

Transport networks:


multiplex

sect

ion layer

fiber fiber

regenera

tor

sect

ion layer

physical la

yer

.... ..

.... ..

HOP link

HOP link connection HOP link connection

HOP link

higher o

rder

path la

yer HOP network connection

matrixconnection

HOP trail

Higher Order Path (HOP) Layer

Transport networks:


higher layer

HOP la

yer

lower layers

fiber

Higher Order Path (HOP) Layer

Transport networks:


matrixconnection

fiber fiber

multiplex

section la

yer

regenerator

section la

yer

physical la

yer

... ...

higher ord

er

path la

yer.....

....... ..

LOP link connection

LOP link

LOP link connection

LOP link

.. ..

LOP trail

LOP network connection

lower ord

er

path la

yer

Lower Order Path (LOP) Layer


Outline



3. WDM

Transport networks:


1 2 3 4 5 6 7 8 910111213141516 270

271

540

272

273

21

61

24

30

21

62

21

63

...frame 1 270 columns

2430 bytes/frame x 8 bits/byte x 8000 frames/sec = 155.52 Mbit/s

1 2 3 4 5 6 7 8 910111213141516 ... 270

271

540

272

273

21

61

24

30

21

62

21

63

...

frame 2 270 columns

9 r

ow

s

...

...

frame 1125 sec

...

frame 2125 sec

......1 2 3 2430 1 2 3 2430

STM-1 frame1 byte/frame = 64 kbit/s

Higher order frames (e.g. STM-4): byte interleaving (1 byte from first VC-4, 1 from second,

…)

Transport networks:


261 columns

...9 ro

ws

RSOH

MSOH

pointer Virtual ContainerVC-4

VC-4: 261 x 9 bytes every 125 sec ==> 150.336 Mbit/s

STM-1 frame

Transport networks:


VC-12 VC-2 VC-3

...VC-4

STM-1 frame


DXC

A

DXC

B

DXC

C

......

...

...

...

...

DXC

Z

...

STM-1

STM-1

STM-1

STM-4

• frame synchronisation• clock synchronisation

...

referenceclockclck

clck

clck

clck

Timing issues


VC TIMING PHASE MAINTAINEDSECTION

OVERHEADALIGNED

A, B, C denote transport signalsF denotes framing bytePx denotes pointer byte value x

FRAMESYNCHRONISATION

MACHINE

"A" in

"B" in

"C" in

"A" out

"B" out

"C" out

A4 A3 A2 A1 P7 F

B3 B2 B1 P5 F

C1 P4 F

P2 F

P3 F

P5 F

A5 A4 A3 A2 A1

B4 B3 B2 B1

C2 C1

Frame Synchronisation


PT J

neg

ati

ve ju

sti

ficati

on

:carr

ier

clo

ck s

low

er

than

receiv

ed

data

clo

ck

PT J

JI J

PT-1 J

frame N

frame N+1

frame N+2

frame N+3

positiv

e ju

stifica

tion :

carrie

r clock is fa

ster

than

rece

ived d

ata

clock

J

PT

PT J

J

JI

PT+1

J

J

Clock Synchronisation: pointer processing


Outline



3. WDM


63xVC12

•••

2Mb/s2Mb/s

2Mb/s

STM-1

VC12VC3VC4

•••

•••

2Mb/s

34Mb/s

140Mb/s

STM-1STM-1STM-1

•••

STM-4STM-4

STM-1STM-1

STM-1

VC4

Multiplexer (MUX)


STM-1 STM-1

bidirectional• • •

2Mb/s2Mb/s

e.g.: 10 tributaries

• • •

STM-16 STM-16

140Mb/s2Mb/s

• • •

34 Mb/s

unidirectional

Add-Drop Multiplexer (ADM)


2Mb/s 34Mb/s 140Mb/s140 Mb/s 140 Mb/s

STM1

STM1

STM1

STM1

STM1

STM1

broadband DXCAU-DXCHO-DXCDXC 4/4

wideband DXCTU-DXCLO-DXC

DXC 4/3/1

Digital Cross-Connects (DXC)


Outline



3. WDM


Ring network architecture

Meshed network architecture

Hybrid network architecture

General architecture

Network architectures


ADMtransitadd

dro

ptransit

Single ring: unidirectional


STM-4 ringHOP ADMs

Single ring: unidirectional


ADM

Single ring: bidirectional


ADMADM

RING 2

ADMADM

RING 1

cloverleaf

hierarchical

centralring

Ring network


DXCDXCring1

ring2

ring1

ring2

AD

MA

DM

AD

MA

DM DXCDXCring

1

ring2

AD

MA

DM

AD

MA

DM

Ring network: Interconnection between rings


DXC

Mesh network


ADMADM

RING

DXCDXC

MESH

Hybrid network: ring/mesh


STM-4 local

regional

core

STM-16

overlayring

STM-16

mesh

General network architecture


Outline

1. Transport network examples2. SDH3. WDM

3.1 Introduction3.2 WDM point-to-point transmission3.3 Components for optical networking

(OTN)3.4 Network elements in OTN3.5 Layer structure in OTN3.6 Network architectures in OTN


fiber

mux demux

6 x 10 Gb/s

...

STM-6

4

..

.

STM-64

WDM Principle


Technology evolution: • PDH: up to 565 Mbit/s• SDH: up to 10 Gbit/s• WDM: up to Tbit/s

Why WDM ?

year

worldtrafficvolume

Voice (+ 5 % / y)

2001 2002200019991998 2003 2004

IP (+ 50-100 % / y)


0.0

1

0.1 1 10

10

0

10

00

10

000

10

000

0Teleph

PDH

SDH

WDM

switch

gra

nula

rity

link

capa

city

Mbit/s

Technology History


0,1

1994 1998 2002 2006 2010

volume of installedWDM equipment

volume of installedSDH equipment

Cap

acit

y in

Gb

it/s

Year

volume of installedPDH equipment

0,01

1

10

100

1000

10000 next generationequipment

Capacity in

crease

at 100% ra

te per year

Technology Introduction


Outline


3.1 Introduction3.2 WDM point-to-point transmission3.3 Optical switching (OTN)3.4 Network elements in OTN3.5 Layer structure in OTN3.6 Network architectures in OTN


1

0.5

01.3 1.61.0

attenuationdB/km

wavelengthm

• low attenuation (1.3 and 1.55 m)• high bandwidth• dispersion• non-linear effects

Optical Fiber


• transmitter: laser diode (tunable / multi-wavelength)

• receiver: photodetector

• wavelength multiplexer / demultiplexer

• optical amplifier

Tx

Tx

Tx

...

WDM

Rx

Rx

Rx

...

WDM

1000 km20 Gb/s

wavelength multiplexing

OA OA OA

Optical components


1520 1540 1560(nm)

gain(dB)

20

10

FIBER FIBER

OPTCALAMPLIFIER

EDFA: Erbium Doped Fiber Amplifier

• limited wavelength band (around 1.54 mm)• gain not flat• no regeneration • noise

Optical components: Optical Amplifier: EDFA

e.g. 8 WDM (no modulation)

with modulationwith modulation


Optical Fiber in Europe


Global Fiber Network


Outline


3.1 Introduction3.2 WDM point-to-point transmission3.3 Optical switching ( OTN)3.4 Network elements in OTN3.5 Layer structure in OTN3.6 Network architectures in OTN


WDM pt-to-pt OTN

Point-to-point connections betw een IP routers Optical netw orking w ith OXCs

IP routers sw itchpackets Opto-electrical

conversion

OXCs sw itchlightpaths


• power splitter / combiner• optical space switch• wavelength (de)multiplexer• wavelength filter• wavelength convertor• optical amplifier (pre- and booster-)• optical regenerator (1R, 2R, 3R)

Basic Components required for OTN


MicroElectroMechanical System (MEMS)

© Lucent

Microscopic mirror• Principle:

• Characteristics:+ limited loss

+ integration ( scalability)

- slow reconfiguration


. . .

. . .

Broadcast-and-Select architecture with Semi-conductor Optical Amplifier (SOA) gates

broadcast select

• Principle:

• Characteristics:- split losses (light signal must be regenerated / limited scalability)

+ multicast possible

+ fast reconfiguration


Arrayed Waveguide Grating (AWG) and Tunable Wavelength Convertors (TWCs)

TWC

TWC

TWC

TWC

TWC

TWC

TWC

TWC

AWGAWG

• Principle:

• Characteristics:+ no splitt losses

+ switching element itself (AWG) is passive device

• fast reconfiguration if TWC fast tunable


Outline




passivesplitter

passivecombiner

A C

1

2

3fiber

drop add

filter

space switch

Network Elements: Wavelength Routing ADM


passivesplitter

fixedfilterspace switch

passivecombiner

A

B

C

D

1

2

3

1

2

3

fiber

Network Elements: Wavelength Routing OXC


passivesplitter

fixedfilter wavelength

convertor

spaceswitch

passivecombiner

1 1

2 2

3 3

1

2

3 3

A

B

C

D

1

2

3

1

2

3

2

1

Network Elements: Wavelength Translating OXC


Outline




OC trail

optical m

ultiplex

sect

ion layer

fiber fiber

optical

transm

ission

sect

ion layer

physical la

yer

.. ..

OC link connection

OC link

OC link connection

OC link

optical

channel l

ayer OC network connection

matrixconnection

fiber

opticalamplifier

OTN layer structure


OPTICALMULTIPLEX

SECTION

OPTICALMULTIPLEX

SECTION

optical transmission

section

TRIBUTARYSIGNALS(e.g. STM-64)

WDMMULTI-PLEXER

WDMMULTI-PLEXER

OPTICAL CROSS-CONNECT

optical amplifieroptical amplifier

TRIBUTARYSIGNALS(e.g. STM-64)

OPTICAL CHANNEL


section


section

OTN layer structure


SDHMULTI-PLEXER

SDH regeneratorSDH regenerator

SDHMULTI-PLEXER

DIGITAL CROSS-CONNECT

SDH PATH

WDMMULTI-PLEXER

WDMMULTI-PLEXER

OPTICAL CROSS-CONNECT

optical amplifieroptical amplifier

OPTICAL CHANNEL

SDH over OTN


• no access to digital signal !

? communication channel ???

? BER measurement ???

? … ???

• monitoring: optical power, wavelength, spectrum, SNR

• signaling: separate wavelength, pilot tone, separate network

OTN Overhead


Outline




OTN ring network(unidirectional)

Optical Ring Networks


3

2

1

Optical Mesh Networks: Wavelength Routing

SDH SDH


3SDH SDH

2

1

Optical Mesh Networks: WavelengthTranslating

1 chapter 7 transport networks: technology examples m. pickavet and c. develder

Documents

transport network examples

transport network technology

transport networks

technology examples

core network topology

international network

backbone network

deutsche telekom slide