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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
ilians-University, M
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
ilians-University, M
unichD
epartment of C
omputer S
cience, Informatik 4
, Aachen U
niversity of Technology
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
ilians-University, M
unichD
epartment of C
omputer S
cience, Informatik 4
, Aachen U
niversity of Technology
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
ilians-University, M
unichD
epartment of C
omputer S
cience, Informatik 4
, Aachen U
niversity of Technology
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
ilians-University, M
unichD
epartment of C
omputer S
cience, Informatik 4
, Aachen U
niversity of Technology
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
ilians-University, M
unichD
epartment of C
omputer S
cience, Informatik 4
, Aachen U
niversity of Technology
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
ilians-University, M
unichD
epartment of C
omputer S
cience, Informatik 4
, Aachen U
niversity of Technology
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
ilians-University, M
unichD
epartment of C
omputer S
cience, Informatik 4
, Aachen U
niversity of Technology
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
ilians-University, M
unichD
epartment of C
omputer S
cience, Informatik 4
, Aachen U
niversity of Technology
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
10Institute for C
omputer S
cience, Ludwig-M
aximilians-U
niversity, Munich
Departm
ent of Com
puter Science, Inform
atik 4, A
achen University of T
echnologyC
hapter0
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
11Institute for C
omputer S
cience, Ludwig-M
aximilians-U
niversity, Munich
Departm
ent of Com
puter Science, Inform
atik 4, A
achen University of T
echnologyC
hapter0
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
12Institute for C
omputer S
cience, Ludwig-M
aximilians-U
niversity, Munich
Departm
ent of Com
puter Science, Inform
atik 4, A
achen University of T
echnologyC
hapter0
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
13Institute for C
omputer S
cience, Ludwig-M
aximilians-U
niversity, Munich
Departm
ent of Com
puter Science, Inform
atik 4, A
achen University of T
echnologyC
hapter0
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
14Institute for C
omputer S
cience, Ludwig-M
aximilians-U
niversity, Munich
Departm
ent of Com
puter Science, Inform
atik 4, A
achen University of T
echnologyC
hapter0
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
15Institute for C
omputer S
cience, Ludwig-M
aximilians-U
niversity, Munich
Departm
ent of Com
puter Science, Inform
atik 4, A
achen University of T
echnologyC
hapter0
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
16Institute for C
omputer S
cience, Ludwig-M
aximilians-U
niversity, Munich
Departm
ent of Com
puter Science, Inform
atik 4, A
achen University of T
echnologyC
hapter0
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
ystems
17Institute for C
omputer S
cience, Ludwig-M
aximilians-U
niversity, Munich
Departm
ent of Com
puter Science, Inform
atik 4, A
achen University of T
echnologyC
hapter0
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
18Institute for C
omputer S
cience, Ludwig-M
aximilians-U
niversity, Munich
Departm
ent of Com
puter Science, Inform
atik 4, A
achen University of T
echnologyC
hapter0
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
19Institute for C
omputer S
cience, Ludwig-M
aximilians-U
niversity, Munich
Departm
ent of Com
puter Science, Inform
atik 4, A
achen University of T
echnologyC
hapter0
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
20Institute for C
omputer S
cience, Ludwig-M
aximilians-U
niversity, Munich
Departm
ent of Com
puter Science, Inform
atik 4, A
achen University of T
echnologyC
hapter0
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
21Institute for C
omputer S
cience, Ludwig-M
aximilians-U
niversity, Munich
Departm
ent of Com
puter Science, Inform
atik 4, A
achen University of T
echnologyC
hapter0
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
22Institute for C
omputer S
cience, Ludwig-M
aximilians-U
niversity, Munich
Departm
ent of Com
puter Science, Inform
atik 4, A
achen University of T
echnologyC
hapter0
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
munication S
ystems
23Institute for C
omputer S
cience, Ludwig-M
aximilians-U
niversity, Munich
Departm
ent of Com
puter Science, Inform
atik 4, A
achen University of T
echnologyC
hapter0
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
ystems
24Institute for C
omputer S
cience, Ludwig-M
aximilians-U
niversity, Munich
Departm
ent of Com
puter Science, Inform
atik 4, A
achen University of T
echnologyC
hapter0
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
munication S
ystems
25Institute for C
omputer S
cience, Ludwig-M
aximilians-U
niversity, Munich
Departm
ent of Com
puter Science, Inform
atik 4, A
achen University of T
echnologyC
hapter0
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
munication S
ystems
26Institute for C
omputer S
cience, Ludwig-M
aximilians-U
niversity, Munich
Departm
ent of Com
puter Science, Inform
atik 4, A
achen University of T
echnologyC
hapter0
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
27Institute for C
omputer S
cience, Ludwig-M
aximilians-U
niversity, Munich
Departm
ent of Com
puter Science, Inform
atik 4, A
achen University of T
echnologyC
hapter0
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
ystems
28Institute for C
omputer S
cience, Ludwig-M
aximilians-U
niversity, Munich
Departm
ent of Com
puter Science, Inform
atik 4, A
achen University of T
echnologyC
hapter0
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
29Institute for C
omputer S
cience, Ludwig-M
aximilians-U
niversity, Munich
Departm
ent of Com
puter Science, Inform
atik 4, A
achen University of T
echnologyC
hapter0
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
30Institute for C
omputer S
cience, Ludwig-M
aximilians-U
niversity, Munich
Departm
ent of Com
puter Science, Inform
atik 4, A
achen University of T
echnologyC
hapter0
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
31Institute for C
omputer S
cience, Ludwig-M
aximilians-U
niversity, Munich
Departm
ent of Com
puter Science, Inform
atik 4, A
achen University of T
echnologyC
hapter0
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
Telecom
munication S
ystems
32Institute for C
omputer S
cience, Ludwig-M
aximilians-U
niversity, Munich
Departm
ent of Com
puter Science, Inform
atik 4, A
achen University of T
echnologyC
hapter0
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
33Institute for C
omputer S
cience, Ludwig-M
aximilians-U
niversity, Munich
Departm
ent of Com
puter Science, Inform
atik 4, A
achen University of T
echnologyC
hapter0
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
cience, Ludwig-M
aximilians-U
niversity, Munich
Departm
ent of Com
puter Science, Inform
atik 4, A
achen University of T
echnologyC
hapter0
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
omputer S
cience, Ludwig-M
aximilians-U
niversity, Munich
Departm
ent of Com
puter Science, Inform
atik 4, A
achen University of T
echnologyC
hapter0
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
36Institute for C
omputer S
cience, Ludwig-M
aximilians-U
niversity, Munich
Departm
ent of Com
puter Science, Inform
atik 4, A
achen University of T
echnologyC
hapter0
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
cience, Ludwig-M
aximilians-U
niversity, Munich
Departm
ent of Com
puter Science, Inform
atik 4, A
achen University of T
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
Departm
ent of Com
puter Science, Inform
atik 4, A
achen University of T
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
aximilians-U
niversity, Munich
Departm
ent of Com
puter Science, Inform
atik 4, A
achen University of T
echnologyC
hapter0
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
aximilians-U
niversity, Munich
Departm
ent of Com
puter Science, Inform
atik 4, A
achen University of T
echnologyC
hapter0
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
aximilians-U
niversity, Munich
Departm
ent of Com
puter Science, Inform
atik 4, A
achen University of T
echnologyC
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
cience, Ludwig-M
aximilians-U
niversity, Munich
Departm
ent of Com
puter Science, Inform
atik 4, A
achen University of T
echnologyC
hapter0
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
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
aximilians-U
niversity, Munich
Departm
ent of Com
puter Science, Inform
atik 4, A
achen University of T
echnologyC
hapter0
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
Departm
ent of Com
puter Science, Inform
atik 4, A
achen University of T
echnologyC
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
omputer S
cience, Ludwig-M
aximilians-U
niversity, Munich
Departm
ent of Com
puter Science, Inform
atik 4, A
achen University of T
echnologyC
hapter0
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
aximilians-U
niversity, Munich
Departm
ent of Com
puter Science, Inform
atik 4, A
achen University of T
echnologyC
hapter0
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
omputer S
cience, Ludwig-M
aximilians-U
niversity, Munich
Departm
ent of Com
puter Science, Inform
atik 4, A
achen University of T
echnologyC
hapter0
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, ....)