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Lehrstuhl für Informatik 4

Kommunikation und verteilte Systeme

Chapter 3.2: The Internet Protocol IP

Result: ARPANET (predecessor of today's Internet)

Goal:• Interconnection of computers and networks using uniform protocols.

• A particularly important initiative was initiated by the ARPA(Advanced Research Project Agency, with military interests).

• The participation of the military was the only sensible way to implement such an ambitious and extremely expensive project.

• The OSI specification was still in developing phase.

On the Way to Today's Internet



Page 2Chapter 3.2: The Internet Protocol IP

Design objective for ARPANET

• The operability of the network should remain intact even after a largest disaster possible, e.g. a nuclear war, thus high connectivity and packet switching

• Network computer and host computer are separated

ARPA

Advanced Research Projects Agency

ARPANET

1969Subnet

ARPANET




A subnet consists of: • Interface Message Processors

(IMPs), which are connected by rented transmission circuits.

• High connectivity (in order to guarantee the demanded reliability)

Host

IMP

Subnet

IMP-IMP

Protocol

Source IMP todestination IMP protocol

Host-host Protocol

Host-IMPProtocol

A node consists of• an IMP

• a host

Several protocols for the communication between IMP-IMP, host-IMP,…

ARPANET




XDS940

DEKPDP-10

XDS1-7

Stanford ResearchInstitutes (SRI)

Universityof Utah

University of CaliforniaLos Angeles (UCLA)

University ofCalifornia SantaBarbara (UCSB)

ARPANET(December 1969)

IMP

IMPIBM

360/75 IMP

IMP California

The Beginning of ARPANET




SRI

UCSB

UCLA

Utah

WITH

Harvard

Illinois

USC

SRI Utah Illinois WITH

USCUCLA

UCSB

Stanford

HarvardAberdeen

CMU

ARPANET in April 1972 ARPANET in September 1972

Very fast evolution of ARPANET within shortest time:

Evolution by ARPANET




Problem: Interworking!Simultaneously to the ARPANET further (smaller) networks were developed.

All the LANs, MANs, WANs

• had different protocols, media,…

• could not be interconnected at first and were not be able to communicate

with each another.

Therefore:

Development of uniform protocols on the transport- and network level (without a too accurate definition of these levels, in particular withoutexact coordination with the respective OSI levels).Result: TCP/IP networks.

Interworking




Developed 1974:

Transmission Control Protocol/Internet Protocol (TCP/IP)

Requirements:

• Fault tolerance

• Maximal possible reliability and availability

• Flexibility (i.e. suitability for applications with very different requirements)

The result:

• Network protocol IP; (Internet Protocol; connectionless)

• End-to-end protocols TCP (Transmission Control Protocol; connection-oriented) and UDP (User Datagram Protocol; connectionless)

TCP/IP




Application Layer

Presentation Layer

Session Layer

Transport Layer

Network Layer

Data Link Layer

Physical Layer

Application Layer

Transport Layer (TCP/UDP)

Internet Layer (IP)

Host-to-Network Layer

ISO/OSI TCP/IP

TCP/IP and the OSI Reference Model




Both models are based on hierarchical protocol suites

Clear separation between:

1. Services2. Interfaces3. Protocols

Changes of protocols are difficult and sometimes nearly impossible

Protocols were implemented beforespecifying the model. The model was little more than a (not alwayssatisfying) description of the system behavior.

protocols fit the model wellThe model was practically not

transferable to other protocols suites

The OSI reference model was deve-loped before OSI protocols and products

The model was not limited to OSI protocols, but generally usable

Protocol designers often hadnot much experience

OSI: TCP/IP:

No comparably clear separation:

TCP/IP vs. OSI




From the ARPANET to the Internet

• 1983 TCP/IP became the official protocol of ARPANET. ARPANET was

connected with many other USA networks.

• Intercontinental connecting with networks in Europe, Asia, Pacific.

• The total network evolved this way to a world-wide available network (called “Internet”) and gradually lost its early militarily dominated character.

• No central administrated network, but a world-wide union from many individual, different networks under local control (and financing).

• 1990 the Internet consisted of 3,000 networks with 200,000 computers. That was however only the beginning of a rapid evolution.




What does it mean: “a computer is in the Internet”?

- Use of the TCP/IP protocol suite

- Accessibility over an IP address

- Ability to send IP packets

In its early period, the Internet was limited to the following applications:

E-mail electronic mail (partly because the US post was not very reliable and the different time zones made telephone accessibility of thetelephone partner more difficult)

Remote login running jobs on external computers

File transfer exchange of data between computers

Internet




• Until 1990: the Internet was comparatively small, only used by universities and research institutions.

• 1990: The WWW (World Wide Web) - first developed by the CERN for the simplification of communication within the field of high-energy physics -became, together with HTML and Netscape browsers, a from nobody foreseen “killer application”; this was the breakthrough for the acceptance of the Internet.

• Emergence of so-called Internet Service Providers (ISP), i.e. companies, which make their computers available as access points to the Internet.

• Millions of new (predominantly non-academic) users!

• New applications, e.g. E-Commerce

• 1995: Backbones, ten thousands LANs, millions attached computers, exponentially rising number of users

• 1998: The number of attached computers is doubled approx. all 6 months

• 1999: The transferred data volume is doubled in less than 4 months

Evolution of the Internet




Evolution of the Internet

• At the beginning of 2003: (estimated) 171 million of hosts attached to the Internet

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20.000.000

40.000.000

60.000.000

80.000.000

100.000.000

120.000.000

140.000.000

160.000.000

180.000.000

200.000.000




Evolution in Europe

Germany

Europe

Number of Hosts

Date

Nu

mb

er o

f H

ost

s




Internet and Intranet

Internet

• Communication via the TCP/IP protocols

• Local operators control and finance

• Global coordination by some organizations

• Internet Providers provide access points for private individuals

Intranet

• Enterprise-internal communication with the same protocols and applications as in the Internet.

� Computers are sealed off from the global Internet (data security)

� Heterogeneous network structures from different branches can be integrated with TCP/IP easily

� Use of applications like in the WWW for internal data exchange




• Promotes communication and the information and data exchange

• In national and international networks

• in particular for institutions and persons from science, research, education and culture

Gigabit-Wissenschaftsnetz (G-WIN)

• Packet switching, on basis of SDH

• Network services

• Connection to international networks, e.g. to the European scientific network and to USA, Russia or China

The association for the promotion of the German research network: Verein zur Förderung einesDeutschen Forschungsnetzes e.V. (DFN)

Gigabit-Wissenschaftsnetz




German G-Win

Connection of the G-WIN to• German Telekom AG/T-Online

(34 MBit)

• DE-CIX, central exchange point of the German Internet Providers (1 GBit)

• US-American Internet (2x 622 MBit)

• European scientific network GÉANT (2.5/10 GBit)

Stuttgart

Leipzig

Berlin

Frankfurt

Karlsruhe

Garching

Kiel

Braunschweig

Dresden

Aachen

RegensburgKaiserslautern

Augsburg

Bielefeld

Hannover

Erlangen

Heidelberg

Ilmenau

Würzburg

Magdeburg

Marburg

Göttingen

Oldenburg

Essen

St. Augustin

Rostock

Global Upstream

GEANT

Hamburg

Core Node10 GBit/s2,4 GBit/s2,4 GBit/s622 MBit/s




GÉANT

• European research network since 2001 (predecessor: TEN-155)

• 2,5 GBit/s Backbone, upgrade to 10 GBit/s (2003)

• Connects more than 30 countries

European scientific network GÉANT

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