telecommunication systems - rwth aachen university

Telecom

munication S

ystems1

Institute for Com

puter Science, Ludw

ig-Maxim

ilians-University, M

unichD

epartment of C

omputer S

cience, Informatik 4

, Aachen U

niversity of Technology

Chapter

0

Prof. D

r. Claudia Linnhoff-P

opienInstitute for C

omputer S

cience Ludw

ig-Maxim


unich

Prof. D

r. Otto S

paniolD

epartment of C

omputer S

cienceA

achen University of T

echnology

Telecom

munication S

ystems

WS

1999 / 2000

• Frank Im

hoff• A

xel Küpper

• Jens Meggers

MM

NTE

AM

The A

achen Staff

(in alphabetical order):• M

arkus Garschham

mer

• Annette K

ostelezkyT

he Munich S

taff(in alphabetical order):

Telecom

munication S

ystems2

Institute for Com

puter Science, Ludw

ig-Maxim


unichD

epartment of C

omputer S


, Aachen U


Chapter

0

Telekom

munikationssystem

e

Verteilte V

orlesung

•Konzeption

•Vorbereitung

•Durchführung

Übertragung

•Konzeption

•Vorbereitung

•Durchführung

•Konzeption

•Vorbereitung

•Durchführung

Teilnahm

e

Vorlesungen

Übungen

Übertragung

Audio, V

ideo, Folien

Audio, V

ideo, Folien

Telecom

munication S

ystems3

Institute for Com

puter Science, Ludw

ig-Maxim


unichD

epartment of C

omputer S


, Aachen U


Chapter

0

Structure I

1. History and D

evelopment of T

elecomm

unications

• Definition of T

elecomm

unications• A

bout Sm

oke Signals, O

ptical Telegraphs, M

orse Telegraphs ...

• Developm

ent and Standardization of M

odern Telephony

• Differentiation betw

een Speech, D

ata and Multim

edia Com

munication

• Fundam

entals of Com

munication E

ngineering (Disturbance, B

andwidth, C

rosstalk)• C

opper and Fiber C

ables, Sea C

ables, Satellite C

omm

unications• M

ultiplexing Techniques (T

DM

, FD

M, C

DM

, ...)• A

nalog Sw

itching Techniques (S

witches, C

rossbars, ...)

2. Analog T

ransmission and S

witching

0. From

Local Area N

etworks to W

ide Area N

etworks

• Differentiation betw

een Local Area N

etworks, W

ide Area N

etworks, ...

• The Internet, IP

Protocols

• B-W

in, the Germ

an Broadband R

eserach Netw

ork• M

bone, H.261

Telecom

munication S

ystems4

Institute for Com

puter Science, Ludw

ig-Maxim


unichD

epartment of C

omputer S


, Aachen U


Chapter

0

Structure II

5. Mobile C

omm

unication• C

ellular Mobile C

omm

unication Netw

orks• D

EC

T S

tandard, GS

M S

tandard• H

andover Techniques, Location U

pdates• N

ext Generation: W

AP

, GP

RS

• Fundam

entals of Digital C

omm

unication (PC

M, S

hannon, A/D

-Conversion)

• Structure and F

unction of Modern D

igital Telecom

munications N

etworks

• Integrated Services D

igital Netw

ork (ISD

N), A

TM

, AD

SL

• Services (P

hone, Fax, F

rame R

elay, X.25, ...)

• Value A

dded Service (F

reephone, Call F

orwarding, V

irtual Private N

etworks)

• Signaling S

ystem N

o. 7 (SS

7) Protocol

• Billing and S

ecurity Aspects of IN

• Universal P

ersonal Telecom

munication (U

PT

)

Database

Sw

itch

Sw

itch

SS

P

Sw

itch

SS

PC

ircuit Sw

itched Telephone N

etwork

Servicelogic

4. Intelligent Netw

orks

3. Digital T

ransmission and S

witching

Telecom

munication S

ystems5

Institute for Com

puter Science, Ludw

ig-Maxim


unichD

epartment of C

omputer S


, Aachen U


Chapter

0

Structure III

6. Managem

ent of Telecom

munication N

etworks

• Fundam

entals of Net M

anagement (F

ault, Perform

ance, Configuration ...)

• Managem

ent Protocols (S

NM

P, C

MIP

)• O

bject oriented and Agent B

ased Managem

ent Concepts

• Telecom

munication M

anagement N

etwork (T

MN

)

• LAN

Coupling w

ith ISD

N• C

orporate Netw

orks• R

eal-Tim

e Data C

omm

unication over IP-based N

etworks (R

SV

P, H

.323, VoIP

)• Integration of IN

in IP-based N

etworks

• Distributed S

ystems and O

bject Orientation

• Middlew

are Platform

s (CO

RB

A, ...)

• Use of M

obile Agents in T

elecomm

unications• T

elecomunication Inform

ation Netw

ork Architecture (T

INA

)

IP netw

orks

?

?

OR

B

TCP

/ IP

LifecycleS

erviceTradingS

erviceM

essagingS

ervice

SS

7 - Stack

...

Application O

bjects

SS

7-E

ntitie

s,

e.g.

IN-S

ervices

7. Converging N

etworks

8. Middlew

are Platform

s, Mobile A

gents

Telecom

munication S

ystems6

Institute for Com

puter Science, Ludw

ig-Maxim


unichD

epartment of C

omputer S


, Aachen U


Chapter

0

Exercises and handouts

•start at Novem

ber, 2nd

•approximately every 14 days

•Tuesdays, betw

een 11.30am and 1.00pm

•Room

: AH

5

Exercises as lectures

Dipl. Inform

. Frank Im

hoffLehrstuhl für Inform

atik 4, Room

4108aP

hone:0241 / 80 - 21416eM

ail: im

hoff@inform

atik.rwth-aachen.de

Questions and appointm

ents

Novem

ber, 9nd,1999

Novem

ber, 23th, 1999

Decem

ber, 7th, 1999

Decem

ber, 21th, 1999

January, 18th, 2000

February, 1st, 2000

all slides will be published at

http://ww

w-i4.inform

atik.rwth-aachen.de/lectures

a couple of days after the respective lecturesand exercises

Handouts

Telecom

munication S

ystems7

Institute for Com

puter Science, Ludw

ig-Maxim


unichD

epartment of C

omputer S


, Aachen U


Chapter

0

Literature

Lüke, H.D

.:E

lektrische Signalübertragung, 4. A

uflage, S

pringer-Verlag 1990

- electrical and engineering aspects of signal distribution - very im

portant for engineers

Siegm

und, G.

:T

echnik der Netze, 4. A

uflage, Hüthig 1999

- recomm

ended as overview over telecom

munications

Tanenbaum

, A.S

.:

Com

puter Netw

orks, 3rd Edition, P

rentice Hall 1997

- recomm

ended as overview over com

puter networks

Jung, V. et. al.

:H

andbuch für die Telekom

munikation, S

pringer 1998

- more technical overview

over telecomm

unication networks

Magedanz, T

h.:Intelligent N

etworks, T

homson 1996

Telecom

munication S

ystems8

Institute for Com

puter Science, Ludw

ig-Maxim


unichD

epartment of C

omputer S


, Aachen U


Chapter

0

Literature

Freem

an, R. L.:

Fundam

entals of Telecom

munications,

Wiley Interscience 1999

- mathem

atical fundamentals

Freem

an, R. L.:

Telecom

munication S

ystem E

ngineering, W

iley Interscience 1996

- mathem

atical and engineering fundamentals

Eberspächer, J. et al.

:G

SM

- Sw

itching, Services and P

rotocols, W

iley 1998

- mobile com

munication netw

orks, esp. GS

M

David, K

. et al.:D

igitale Mobilfunksystem

e, Teubner 1996

- mobile com

munication netw

orks

Telecom

munication S

ystems9

Institute for Com

puter Science, Ludw

ig-Maxim


unichD

epartment of C

omputer S


, Aachen U


Chapter

0

Telecom

munications

What is T

elecomm

unications?

• the world’s m

ost lucrative industry

• more than 1,800 m

illion subscribers worldw

ide

• 900,000 million U

S-D

ollars annual expenditures

• fastest growing m

arket in the future

Som

e Definitions

• Brockhaus E

ncyclopedia: Com

munications at a distance

• IEE

E D

ictionary: Transm

ission of Signals over long distance,

such as by telegraph, radio or television

• more com

mon: E

lectrical comm

unication

Telecom

munication S

ystems

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Motivation and D

efinition

Our F

ocus:

Telecom

munication encom

passes the optical and electrical long

distance transmission of voice, data, and im

age information

(e.g. TV

, facsimile)

over different types of media

, such as fiber optics, copper, or radio.

Telecom

munications

and T

elecomm

unication System

s

Telecom

munication S

ystems

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Com

munication C

oncepts

Data C

omm

unication

Voice C

omm

unication

•com

munication m

ostly between com

puters•

multiple types of data (video, file transfer, control

comm

ands)•

different Quality-of-S

ervice (QoS

) demands

•varying data rates, bursty traffic

•high security dem

ands (e.g., banking)

•low

QoS

demands

•low

bit rates (up to 64kBit/s)

•low

security standards

First com

munication netw

orks have mainly or exclusively been used for

voice and (later) for facsimile

Telecom

munication S

ystems

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Com

mercial facts

Estim

ated Investments in G

ermany for 1999

13.6 billion DM

(15.3 billion DM

in 1998)

Estim

ated turnover in Germ

any’s telecomm

unication markets

106 billion DM

(same as in 1998)

Increase of telephone traffic

more than 20 percent per year

Telecom

munication S

ystems

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Technical facts

Fiber C

abling in Germ

any 1999

more than 237,000 km

Internet users in Germ

any

•7.5 million in 1/99 and approx. 9 m

illion in 1/2000

•(if we survive W

EIT

UK

AE

, i.e. the Y2K

problem!)

•highest increase in Europe (in absolute num

bers)•but still last place w

ith respect to PC

usage (per capita!)

•more than 20 m

illion in 2002

Mobile com

munication subscribers in G

ermany

End of June: 16.9 m

illion (20,6 percent) - estim

ated for end of the year: 21 million

(place two in E

urope after Italy in absolute numbers;

but Finland is m

uch much higher in relative num

bers)

Telecom

munication S

ystems

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Data transm

ission

Driving forces behind data transm

ission:

•dramatic and continuing decrease in com

puter hardware costs

•increase in computer hardw

are power

Exam

ple:

•costs of a modern personal com

puter less than $1,000

•equal to the capability of an IBM

mainfram

e from 10 years ago

•more than 100 m

illion of transistors•100 m

illion sheets of toilet paper would run to m

ore than $100,000

Virtually“free”

computing

power

Telecom

munication S

ystems

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Data transm

ission

•V

oice and video annotation of files

•Im

age processing•

Multim

edia authoring

•S

peech recognition

•V

ideo conferencing

•S

ophisticated engineering and scientific applications

increasing number of system

s

increasing power

at single sites: office buildings,factories, operations center ...

Telecom

munication S

ystems

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Distributed resources

Additional requirem

ents occur at the same tim

e:

•exchange messages w

ithin facilities

•retrieve data from other resources

•share and exchange data between system

s

•share project-related information w

ith other mem

bers of a work group

•share expensive resources, as e.g., video equipment, etc.

(cost of processor hardware has dropped far m

ore rapidly than the cost ofother resources)

sharing requires some kind of client-server architecture

Telecom

munication S

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Social issues

social, ethical, political problems of com

munication netw

orks

newsgroups, bulletin boards

•politics, religion, sex•not lim

ited to text, photography, video•problem

of responsibility for content

eMails

•censoring•control of em

ployees, students, citizens•possibility of anonym

ous messages

•responsibility of the network provider for transm

itted content?

•responsibility of newsgroup operators for postings?

•user’s rights of free speech?

•problem of anonym

ous accusations and violation of laws?

Com

munication netw

orks allow ordinary people to distribute their view

s indifferent w

ays and to different audiences faster, cheaper, and less censoredthan w

as previously possible

Telecom

munication S

ystems

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First steps tow

ards networks

Electric or electronic com

munication betw

een at least two different

points requires:

• National vs. international standardization

• Com

plexity of technical problems

• Com

petition between com

panies involved

• Industrial and military developm

ent is often confidential

• Standardization is far too slow

(for many, m

ostly non-technical reasons)

Telecom

munication S

ystems

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Standardization organizations

International Telecom

munication U

nion - ITU

• Geneva, S

witzerland

• more than 1,000 S

tandards

• ITU

-R: R

adio Com

munication S

ector

(former International C

onsultative Com

mittee for R

adio - CC

IR)

• ITU

-T: T

elecomm

unications Sector

(formerly know

n as International Consultative C

omm

ittee for Telephone and

Telegraph - C

CIT

T)

European T

elecomm

unication Standardization Institute - E

TS

I

•e.g. responsible for the G

lobal System

for Mobile

Com

munication (G

SM

) Standard

ww

w.itu.org

ww

w.etsi.org

Telecom

munication S

ystems

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Standardization O

rganizations

Internet Engineering T

ask Force

Institute of Electrical and E

lectronic Engineers - IE

EE

•defines S

tandards, such as the802.X

-Standards for Local A

rea Netw

orks

Am

erican National S

tandards Institute - A

NS

I

ww

w.ieee.org

ww

w.ansi.org

ww

w.ietf.org

various international industry consortia•

developing industry standards often faster and more successful

than non comm

ercial organizations (e.g. Fast E

thernet, JAV

A etc.)

Telecom

munication S

ystems

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ISO

International Standards O

rganization - ISO

•voluntary, non-treaty organization

•founded in 1946

•m

embers are the national standards organizations of 89 countries

•issues standards of subjects, ranging from

nuts and bolts totelephone pole coatings

•has alm

ost 200 Technical C

omm

ittees (TC

), each dealing with a

specific subject (e.g. TC

97 deals with com

puter and information

processing)•

each TC

has subcomm

ittees which are subdivided into w

orkinggroups

•on issues of telecom

munication standards, IS

O and IT

U-T

oftencooperate (IS

O is a m

ember of IT

U-T

)

•D

ata Com

munications S

tandards (ISO

-OS

I-Reference M

odel)

ww

w.iso.ch

Telecom

munication S

ystems

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ISO

- OS

I Reference

Reference M

odel for Open S

ystem Interconnection

Presentation layer

and session layerhave rarely been

implem

ented

Data link layer and

network layer are

overloaded

Application Layer

7

Presentation Layer

6

Session Layer

5

Transport Layer

4

Netw

ork Layer3

Data Link Layer

21

provides interface toend-user process andstandardized services toapplications

provides reliable packetdelivery m

echanism

handles addressingand routes packets

controls physical dataflow

Physical Layer

interface between

network m

edium and

devices

Main points of

critique

Telecom

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Critique of the O

SI M

odel

1. Bad T

iming

TC

P/IP

protocols were already available by the tim

e the OS

I protocolsappeared

2. Bad T

echnology

•alm

ost prohibitive complexity (easily thousand pages specifications for

just one standard)

•both the m

odel and the protocols have weaknesses

•the real reason for so m

any layers might have been the IB

M seven-

layer System

s Netw

ork Architecture (S

NA

) protocol

Telecom

munication S

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Critique of the O

SI M

odel

4. Poor Im

plementations

•due to the enorm

ous complexity initial im

plementations w

ereinadequate

•the “poor quality” im

age stuck

•in contrast, quite good im

plementations of com

peting TC

P/IP

protocolsw

ere part of free UN

IX im

plementations

3. Bad P

olitics

OS

I was perceived as a creature of E

uropean telecomm

unicationsm

inistries, the European C

omm

unity, and later the U.S

. Governm

ent

only a few organizations interested, m

ostly European telecom

munication

monopolists

Telecom

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Local Area N

etworks

•typically w

ithin a single building or a cluster of buildings (10 - 1000m)

•ow

ned by the same organization that ow

ns the attached devices

•data rates of LA

Ns are typically very high (currently up to 1,000 M

bit/s)

LAN

Topologies

•bus(easy cabling, low

costs,low

performance ≤ 10M

bit/s)

•star(high perform

ance, high costs, high faulttolerance)

•ring(m

edium perform

ance, medium

costs)

Telecom

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Exam

ples

Arcnet (4 M

bit/s)- coaxial cable- star or bus, m

ax. 50m

Ethernet (IE

EE

802.3, 10 MB

it/s)- coaxial, tw

isted pair copper- bus, typical 200m

, up to 2000m

Token R

ing (IEE

E 802.5, 4/16 M

bit/s)- tw

isted pair- logical and physical bus but star cabling

Fast-E

thernet (IEE

E 802.3a, 100 M

bit/s)- tw

isted pair, optical fiber- star, 100m

(twisted pair)

Gigabit-E

thernet (IEE

E 802.3ab, 1,000 M

bit/s)- optical fiber, tw

isted pair (25m)

Telecom

munication S

ystems

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Metropolitan A

rea Netw

orks

Metropolitan

Area N

etworks

•In between LA

Ns and W

AN

s (1 - 10km)

•Moderate to high data rates (10 - 622 M

bit/s)

•Slightly higher error rates and delay com

pared to LAN

s•C

apability to perform local netw

orking of integrated voice and data

Bus A

Bus B

Direction of flow

on A

. . .

Direction of flow

on B

12

3N

Head-E

nd

Com

puter

Exam

ple: Distributed Q

ueue Dual B

us (DQ

DB

, IEE

E 802.6)

Telecom

munication S

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Wide A

rea Netw

orks

Wide A

rea Netw

orks

•Cover large geographical areas (>

10km); m

ainly irregular topology•R

equire public right-of-way (m

ay cause major problem

s, especially in Germ

any!) •R

ely at least in part on circuits provided by a comm

on carrier

•Typically consist of a num

ber of interconnected switching nodes

•Provide relatively m

odest capacity to subscribers (9,600 Bit/s - 2,048 M

bit/s)

Subnet

Router

Host

LAN

Telecom

munication S

ystems

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Com

parison

0.1m1m

10m100m

1km10km

100km

0.01 Mbit/s

0.1 Mbit/s

1 Mbit/s

10 Mbit/s

100 Mbit/s

Multiprocessor

Wide A

reaN

etwork

Local Area

Netw

ork

MA

N

Wide A

rea Netw

orks:

•decreasing costs

•increasingtransm

issioncapacity

Metropolitan A

reaN

etworks are

(almost) obsolete

Telecom

munication S

ystems

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Alternative developm

ent

In the 1960s, J.C.R

. Licklider (1915-1990) published his ideas about the futurerole of interactive com

puting in two papers:

"Man-C

omputer S

ymbiosis"

"The C

omputer as a C

omm

unication Device"

Em

erging problem:

How

to interconnect computers and netw

orks which use

different comm

unication protocols?

available@

i4

Telecom

munication S

ystems

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Alternative developm

ent

•H

is vision was an im

portant contribution to challenging people to examine the

implications of an em

erging technology.

The predecessor of our today’s Internet w

as born

•T

he projects sponsored by AR

PA

defined the research directions in the U.S

. for

many years

•F

urthermore, A

RP

A w

as the first to provide the significant public funding in this field

necessary to guarantee the financial stability on which long-term

research depends

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munication S

ystems

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The A

RP

AN

ET

In the mid-1960s U

.S. D

epartment of D

efensew

anted a comm

and and control network

•able to survive a nuclear war

•no centralized structure because of vulnerability

•packet-switched netw

ork

•consisting of subnets and host computers

AR

PA

Advanced R

esearchP

rojects Agency

AR

PA

NE

T

Dec. 1969

Subnet

Telecom

munication S

ystems

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echnologyC

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The A

RP

AN

ET

A S

ubnet consists of

•Interface Message

Processors (IM

P)

•connected by leasedtransm

ission lines (56kbit/s)

A N

ode of the netw

ork consisted of

•a Host C

omputer

•an IMP

Host

IMP

Subnet IM

P-IM

P

Protocol

Source IM

P to

destination IMP

protocol

Host-host P

rotocol

Host-IM

PP

rotocol

Telecom

munication S

ystems

34Institute for C

omputer S

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First steps of A

RP

AN

ET

AR

PA

NE

Tprotocols could notbe used overm

ultiple networks

Problem

:X

DS

940

DE

CP

DP

-10

XD

S1-7

Stanford R

esearchInstitute (S

RI)

Universityof U

tah

University of C

aliforniaLos A

ngeles (UC

LA)

University of

California S

antaB

arbaraF

irst AR

PA

NE

T(D

ecember 1969)

IMP

IMP

IBM

360/75IM

P

IMP

California

Telecom

munication S

ystems

35Institute for C

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atik 4, A


echnologyC

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Grow

th of AR

PA

NE

T

SR

I

UC

SB

UC

LA

Utah

MITH

arvard

Illinois

US

C

SR

IU

tahIllinois

MIT

US

CU

CLA

UC

SB

Stanford

Harvard

Aberdeen

CM

U

AR

PA

NE

T in A

pril 1972A

RP

AN

ET

in Septem

ber 1972

Trem

endous growth in first three years

Problem

:

Telecom

munication S

ystems

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Interworking

The problem

:

Many Local A

rea Netw

orks, Metropolitan A

rea Netw

orks and Wide

Area N

etworks

- with different protocols, m

edia, and topologies

- without a suitable possibility for netw

ork interconnection

The solution:

A w

orldwide T

CP

/ IP based netw

ork

Telecom

munication S

ystems

37Institute for C

omputer S

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echnologyC

hapter0

TC

P/IP

Reference M

odel

1974:

Transm

ission Control P

rotocol / Internet P

rotocol (TC

P / IP

)

Requirem

ents:

•F

ault tolerance (independent of any event, e.g. node crash or network

failure, caused by every kind of damage w

hich one could ever imagine)

•R

eliability - as high as possible

•F

lexibility (suitable for different applications with divergent

requirements)

The adopted solution:

•E

nd-to-end protocols TC

P and U

DP

(transport layer)

•P

acket switched netw

ork

•C

onnectionless network protocol IP

Telecom

munication S

ystems

38Institute for C

omputer S

cience, Ludwig-M

aximilians-U

niversity, Munich

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atik 4, A


echnologyC

hapter0

TC

P/IP

Reference M

odel

AR

PA

NE

TS

AT

NE

TP

acket Radio

LAN

IP

TC

P

UD

P

TE

LNE

T F

TP

S

MT

P

DN

S

Netw

orks

Protocols

Application Layer

Transport Layer

Netw

ork Layer

Data Link +

Physical Layer

TC

P (T

ransmission C

ontrol Protocol):

Reliable, connection-oriented, allow

ing a bytestream

originating on one machine to be delivered on any other m

achine.

UD

P (U

ser Datagram

Protocol):

Less reliable, connectionless protocol without flow

control and sequencing.

Telecom

munication S

ystems

39Institute for C

omputer S

cience, Ludwig-M

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niversity, Munich

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OS

I vs. TC

P/IP

Both reference m

odels are based on the concept of a stack of independent protocols

Separates clearly betw

een:

1. Services

2. Interfaces 3. P

rotocols

Protocol m

odifications areextrem

ely difficult or impossible

Protocols cam

e first and the model w

asjust a kind of description

protocols match the m

odel very well

difficult or impossible to apply the

model for other protocol suites

OS

I reference model cam

e earlier

than the OS

I protocols

Not lim

ited to specific protocols

Protocol designers did not have

much practical experience

OS

I:T

CP

/IP:

No sim

ilar separation exists:

Telecom

munication S

ystems

40Institute for C

omputer S

cience, Ludwig-M

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niversity, Munich

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Interconnection between

different types of networks

Host

802.5LA

N

M

M

M

MultiprotocolR

outer

Internet

SN

A W

AN

WA

N-W

AN

802.3 LAN

LAN

-WA

N-LA

N

MB

Bridge

802.3LA

N

LAN

-LAN

LAN

-WA

N

802.3LA

N

Telecom

munication S

ystems

41Institute for C

omputer S

cience, Ludwig-M

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niversity, Munich

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hapter0

The Internet

•1983 T

CP

/ IP becam

e the only official protocol of the AR

PA

NE

T

•A

RP

AN

ET

and many regional netw

orks were interconnected

•C

onnections were m

ade to networks in C

anada, Europe, and

the Pacific

•S

ometim

e in the mid-1980s, people began view

ing thecollection of netw

orks as an internet, and later as the Internet

•1990 the Internet had grow

n to 3,000 networks and 200,000

computers and grow

th continued exponentially

Telecom

munication S

ystems

42Institute for C

omputer S

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niversity, Munich

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The Internet

What does “to be on the Internet” actually m

ean ?

a machine that:

runs the TC

P / IP

protocol stack,

has an IP address, and

has the ability to send IP packets all over the w

orld.

Many personal com

puters have the ability to call an Internet service providerand be assigned a tem

porary IP address.

Traditional m

ain applications of the Internet

eMail

Com

pose, send, and receive electronic mail

New

sN

ewsgroups in w

hich users exchange messages

Rem

ote LoginU

ser can log into other machines

File T

ransferC

opying files from one m

achine to another

Telecom

munication S

ystems

43Institute for C

omputer S

cience, Ludwig-M

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The Internet

•till 1990: Internet alm

ost exclusively used by academia for research,

paper distribution, email, ...

•T

he WW

W (W

orld Wide W

eb), in conjunction with H

TM

L and

browsers, w

as the breakthrough of the Internet (“killer application”)

Millions of new

, non-academic and com

mercial users!

(E-C

omm

erce!)

•1992: one m

illion hosts

•1995: m

ultiple backbones, hundreds of mid-level netw

orks, tens of

thousands of LAN

s, millions of hosts, and ten m

illions of users

•1998: host num

ber doubles every six months

Telecom

munication S

ystems

44Institute for C

omputer S

cience, Ludwig-M

aximilians-U

niversity, Munich

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hapter0

The Internet

•1999: T

ransmitted data volum

e doubles within 100 days

Internet Hosts

21333.000

535.0003.212.000

56.218.000

0

10.000.000

20.000.000

30.000.000

40.000.000

50.000.000

60.000.000

8182

8384

8586

8788

8990

9192

9394

9596

9798

9900

Telecom

munication S

ystems

45Institute for C

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TC

P / IP

address space

•E

ach host and router on the Internet has an IP address w

hich encodes itsnetw

ork number and host num

ber

•N

o two m

achines have the same IP

address

•IP

addresses have 32 bits and are used within the S

ource Address and

Destination A

ddress fields of IP packets

•M

achines connected to multiple netw

orks have a different IP address on

each network

0N

etwork

Host

10N

etwork

Host

110N

etwork

Host

Class

ABC

32 Bits

127 Netw

orks2

24 Hosts

16383 Netw

orks2

16 Hosts

2097151 Netw

orks256 H

osts

Telecom

munication S

ystems

46Institute for C

omputer S

cience, Ludwig-M

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niversity, Munich

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IP addresses

Exam

ple137.226.12.169

Class B

addressof R

WT

H A

achen

1000100111100010

Class B

addressidentifier

0111000010101001

Subnet

(e.g. Informatik 4)

Term

inal “B

adger”

255.255.255.0 = 11111111 11111111 11111111 00000000

Subnet m

ask

length of complete subnet address

Telecom

munication S

ystems

47Institute for C

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Lack of addresses

Problem

s

•T

oo many class A

addresses have been reserved in the early years•

Address structure is inefficient

Exam

ple

A com

pany needs address space for 500 hosts

�a class B

address is needed but more than 65000 host addresses are unused

Solution

More addresses

�IP

Version 6 has 16 B

yte (i.e. 128 Bit) addresses

�7 x 10

23 IP address per square m

eter (including oceans!) �

one address for every molecule on the earth surface!

But : the future of IP

v6 is still far from clear! (easier designed than im

plemented

on a large scale; interoperability, costs, migration, ....)

telecommunication systems - rwth aachen university

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