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1 Internet: Technology, Protocols and Services Henning Scbulzrinne GMD Fokus, Berlin [email protected] TU Berlin, WS 1995/96 c 1995, Henning Schulzrinne Credits A.M. Rutkowski, Internet Society Jim Kurose, University of Massachusetts
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Page 1: Internet: Technology, Protocols and Serviceshgs/teaching/internet/intro2.pdf · may be connected to the Internet ... Internet : “collection of networks and routers that spans 61

1

Internet: Technology, Protocols and Services

Henning ScbulzrinneGMD Fokus, Berlin

[email protected]

TU Berlin, WS 1995/96

c 1995, Henning Schulzrinne

Credits

� A.M. Rutkowski, Internet Society

� Jim Kurose, University of Massachusetts

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2

Introduction

� Course Objectives, Prerequisites, Overview

� Readings

� A Brief History of the Internet

� How big is the Internet?

� Who runs the Internet?

� The Internet View of the World

� Subnetwork technology

� Internet technology and Standards

Course Objectives

� understand Internet technology, terminology, issues, constraints

� evaluate alternatives, strengths, weaknesses

� ability to design Internet applications

not: how to use services (email, WWW, ...)

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3

Prerequisites

� introductory course in networking

� know Ethernet, packet vs. circuit switching, OSI layers, .. .(but we’llrefresh your memory)

� a bit of C (some programming examples)

� no performance evaluation or statistics needed

� . . .but a bit of English for slides

Course Overview

� overview of history, standardization, design principles

� network components and addressing

� network, transport: IP, UDP, TCP

� mapping addresses: ARP and DNS

� programming the Internet: socket services

� routing: RIP, OSPF, BGP, ...

� IP multicast and MBONE

� IPv4! IPv6 (IPng)

� traditional data services: ftp, telnet, nntp, smtp (and MIME)

� global clock synchronization: NTP

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4

� World-Wide Web

� real-time services: RTP, RSVP

� network management with SNMP

� Internet as the global information infrastructure?

� site visit: networks and services at GMD

http://www.fokus.gmd.de/step/hgs/internet/

References

[1] D. E. Comer, Internetworking with TCP/IP, vol. 1. Englewood Cliffs,New Jersey: Prentice Hall, 3rd ed., 1995.

[2] D. C. Lynch and M. T. Rose, Internet system handbook. Reading,Massachusetts: Addison-Wesley, 1993.

[3] A. S. Tanenbaum, Computer Networks; Second Edition. Prentice-Hall,2nd ed., 1988.

[4] D. E. Comer and D. L. Stevens, Internetworking with TCP/IP, vol. 2.Englewood Cliffs, New Jersey: Prentice Hall, 1991.

[5] C. Partridge, Gigabit networking. Reading, Massachusetts:Addison-Wesley, 1993.

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Introduction

What is the Internet?

internet, intranet: connection of different LANs within an organization

� private

� may use leased lines

� usually small, but possibly hundreds of routers

� may be connected to the Internet (or not), often by firewall

(the) Internet : “collection of networks and routers that spans 61 countriesand uses the TCP/IP protocols to form a single, cooperative virtualnetwork”. (Comer)

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Internet Actors

Started by U.S. research/military organizations:

(D)ARPA: (Defense) Advanced Research Projects Agency ➠ fundstechnology with military usefulness

DoD: U.S. Department of Defense ➠ early adaptor of Internet technologyfor production use

NSF: National Science Foundation ➠ funds university research

A Short History of the Internet: 1960’s

1830: telegraph

1876: circuit-switching (telephone)

early 1960’s: concept of packet switching (Paul Baran)

1965: MIT’s Lincoln Laboratory commissions Thomas Marill to studycomputer networking

1968: ARPAnet contract awarded to Bolt Beranek and Newman (BBN)

1969: ARPAnet has 4 nodes (UCLA, SRI, UCSB, U. Utah), connected byIMPs (interface message processors); connected by 50 kb/s lines

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7

A Short History of the Internet: 1970’s

� multiple access networks: ALOHA, Ethernet (10 Mb/s)

� companies: DECnet (1975), IBM System Network Architecture (1974)

1971: 15 nodes and 23 hosts: UCLA, SRI, UCSB, U of Utah, BBN, MIT,RAND, SDC, Harvard, Lincoln Lab, Stanford, UIU(C), CWRU, CMU,NASA/Ames

1972: First public demonstration at ICCC

1973: TCP/IP design

1973: first satellite link from California to Hawaii

1973: First international connections to the ARPANET: England andNorway

1979: ARPAnet � 100 nodes

A Short History of the Internet: 1980’s

� proliferation of local area networks: Ethernet and token rings

� late 1980’s: fiber optic networks; fiber distributed data interface(FDDI) at 100 Mb/s

1980’s: DARPA funded Berkeley Unix, with TCP/IP

1981: Minitel deployed in France

1980-81: BITNET (IBM protocols) and CSNET (NSF-funded! 200 sites)

Jan. 1, 1983: flag day: NCP! TCP

early 1980’s: split ARPANET (research), MILNET (military)

1984: Domain Name Service replaces hosts.txt file

1986: NSFNET created (56 kb/s backbone)

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8

Nov. 1, 1988: Internet worm

1989: Internet passes 100,000 nodes

1989: first proposal for World-Wide Web

1989: NSFNET backbone upgraded to T1 (1.544Mbps)

A Short History of the Internet: 1990’s

� high-speed networks: Asynchronous Transfer Mode (ATM) at 150Mb/s and higher

� focus on new applications

� wireless local area networks

� commercialization

� National Information Infrastructure (NII) (Al Gore, U.S. VP)

1990: Original ARPANET disbanded

Fall 1991: CSNET discontinued

1991: Gopher released by University of Minnesota

1992: NSFNET backbone upgraded to T3 (44.736Mbps)

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9

March 1992: First MBONE audio multicast

November 1992: First MBONE video multicast

February 1993: NCSA Mosaic

June 1993: 1,776,000 hosts

April 30, 1995: NSFNET backbone disbanded

The T1 NSFNET Byte Volume ��������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������

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10

How Big is the Internet?

Many measures:

� networks (routed entities)

� domains, host names (but: several names per host!)

� directly (continuously) attached hosts (“ping’able”)

� IP-connected hosts (SLIP, PPP)

� firewalled hosts

� e-mail reachable

“Consumer” Internet

Internet access through on-line services:

� America Online (AOL; 5 mio subscribers)

� Compuserve (3.6 mio subscribers, 100,000 in Germany)

� Prodigy (2 mio “members”)

� T-Online/Datex-J (750,000 in Germany)

� lots of small ones

or count people with access to services

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11

Internet User Populations

email only

(X.400, FIDO,...)

widget.com

core Internet

SLIP/PPP

firewalled

services

on-line

7.8 mio.

10 mio.

11.5 mio.

Copyright © 1995 Larry Landweber and the Internet Society. Unlimited permission tocopy or use is hereby grantedsubject to inclusion ofthis copyright notice.

INTERNATIONAL CONNECTIVITY Version 14 - 6/15/95

Internet

Bitnet but not Internet

EMail Only (UUCP, FidoNet)

No ConnectivityThis map may be obtained via anonymous ftpfrom ftp.cs.wisc.edu, connectivity_table directory

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12

Who’s on the Internet?

July 1994

Domain Name Code Internet Hosts GNP Total (M$) GNP/Host

Iceland is 3,268 5,456 1.67

Australia au 127,514 290,522 2.28

Norway no 38,759 98,079 2.53

Finland fi 49,598 129,823 2.62

U.S. Total var 2,044,716 5,694,900 2.79

New Zealand nz 14,830 46,200 3.12

Sweden se 53,294 202,498 3.80

Netherlands nl 59,729 249,600 4.18

Canada ca 127,516 542,774 4.26

Czech Republic cz 5,639 25,600 4.54

Switzerland ch 47,401 238,050 5.02

U.K. uk 155,706 923,959 5.93

South Africa za 15,595 96,000 6.16

World Median ww 3,225,177 19,935,936 6.18

Israel il 8,464 56,400 6.66

Denmark dk 12,107 91,100 7.52

Hong Kong hk 9,141 71,303 7.80

Austria at 20,130 164,100 8.15

Chile cl 3,703 30,500 8.24

Germany de 149,193 1,495,679 10.03

Slovak Republic sk 868 9,300 10.71

Copyright © 1995 A.M.Rutkowski

Demand for Global Domain NamesDemand for Global Domain Names

100

1,000

10,000

100,000

1,000,000

Dec.92 Dec.93 Dec.94 Dec.95

Commercial Companies

Source: Mike Walsh, NSI

Non-Profit Companies

Network Operators

Registrations

Universities

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13

Internet Growth

Two metrics: number of IP-connected hosts, domain names

year

Inte

rnet

hos

ts

102

103

104

105

106

107

80 82 84 86 88 90 92 94 96 98

GermanyIP connectivityTotal

Most popular on-line services

1. E-Mail

2. Downloads

3. Internet access

4. News on Topics (includes sports scores)

5. Info and Reference

6. Chat

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14

Internet Traffic Report

year

Gig

abyt

es/m

onth

10−2

10−1

100

101

102

103

104

105

1991 1992 1993 1994 1995

newsemailWWWgopherftpTotal

Internet Services

January 1995 NSFnet

ftp31%

WWW18%

unknown14%

news12%

email6%

MBONE5%

login4%

gopher4%

dns3%

irc2%

X111%

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15

��������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������

��������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������

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16

Who runs the Internet?

� “nobody”

� standards: Internet Engineering Task Force (later.. .)

� names: Internic (US), RIPE (Europe), .. .

� numbers: IANA (Internet Assigned Numbers Authority)

� operational coordination: IEPG (Internet Engineering Planning Group)

� network: ISPs (Internet Service Providers), NAPs (Network AccessPoints), DFN, ...

� fibres: telephone companies (mostly)

� content: thousands of companies, universities, individuals, . . .

Who pays for the Internet?

on-line services

NAPInternic

national network(MCI, Sprint, ...)

regionalnetwork

ISP ISPcompany university

log-in via modemshell LAN

internationallines

56 kb - 2 Mb

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17

How is the Internet paid for?

Generally: distance-insensitive

dial-up: per minute (peak/off-peak) or flat monthly

direct connection: flat rate or volume bands; rarely extra for internationalbytes; no time zones

$ German telephone: 4 time zones, 4 distance zones, plus internationaltariffs➠ may change with reserved bandwidth!

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Network Access and Interconnection

NAP

nationalnetwork R R R

R

Ethernet

firewallfirewall

T3

company

point-of-presence(POP)

regional network

localtelephonecompany

phone lines+node

telephoneswitch

PC

modemphonecompany

56kb/s- 2Mb/s

regionalnetwork

NAP

modemconcentrator

Network Interconnection ��������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������

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Chicago NAP ��������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������

Internet in Germany

USA Germany

highest access speed 45 Mb/s 2 Mb/s

high-speed access $12,000/a (1.5 Mb/s) $253,000/a (2 Mb/s)

ATM 155 Mb/s fixed $7899/month $26700/month

ATM traffic free $1834/hour

local (ISDN) calls free $0.80/h

data networks leased lines X.25

Internet use upper-income males CS students

service offerings White House, FTD universities, Spiegel

student use sociology freshmen CS PhDs

on-line users O(5 mio.) 100,000 (700,000 Btx)

president on line yes no

Post Office on line yes Btx?

computer use (households) 36% 40%

equipped with modems 53%

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20

JTC

The Standards-Making Universe

ISO-IECSC6

ECSAS1X1

M1E1

Y1

Q1

TC321

15 2029CAC

CCIR CCITT

CCIR

ITUCCITTTTA

802.2.3

.4 .5.6.7

.8

S3

T5

T9

T1T2

ANSI X3

V1

26

24

18

22

11

2

7

1715

141

EDI

REG

SC21

13

83

27 25

23

CEPT

ECMA

RCR

EIA/TIA

TR41TR8

TR29TR30

CBEMA

STDS

TTC(UP)

TTC(down)

CCIRITU

CCITT

ISO/IECCTSAC

*

.1

IEEE

InternationalCoordinatingOrganizations ECSA-T1

2

1

3 4

5

7

15

11

6

13

14

1012

89

ITU-T

DIN

EMUG

AFNOR

BSI

RARERIPE

EDIFACT

BCS

JISC

JSA

NISTOIW

SPAGPOSI

GROUP

C0SNNI

IEC

MicrosoftMAPI

OpenSoftware

Fdn

UnixInt’l

X-WindowsConsortium

SIGMAGroup

X/Open VESA StdsAss’n

NAISDN Users

Forum

NetworkManagem’t

Forum

SMDSInterestGroup

EuroFRForum

FrameRelayForum

ATMForum

SMPTE

URSI

RadioConf

B’castUnions

ITU-R

48

9

7

11

1012

56

InternetSociety IANA* PCR*

IETF

PCS

HATSConf

CSRG

JATE

AustralianCCITT

ATSSOAS

ETSI

BT

NA

SPS

NA

NANA

NA NA

NA

Traditional Model Telco BodiesTraditional Model InformationSystems Bodies

New Model InformationSystems BodiesNew Model

Telco Bodies

TraditionalRadioBodies

WinsockGroup

EWOSCEN

CENELEC

CSASCC

SIS

SNV

POSIX

A.M.Rutkowskicopyright 1994

Standards Making ProcessesStandards Making Processes

Stage 1:Stage 1:InitialInitialRequirementsRequirements

VendorsVendors

Stage 2:Stage 2:Base StandardsBase StandardsDevelopmentDevelopment

X3X3T1T1CCITTCCITTISO/IEC JTC1ISO/IEC JTC1IEEEIEEEEIT/TIAEIT/TIA

Stage 3:Stage 3:Profiles/ProductProfiles/ProductDevelopmentDevelopment

OIWOIWEWOSEWOSAOWAOWMAP/TOPMAP/TOPVendorsVendorsJTC1/SGFSJTC1/SGFSConsortiaConsortia

Stage 4:Stage 4:TestingTesting

COSCOSNVLAPNVLAPEOTCEOTCVendorsVendors

Stage 5:Stage 5:UserUserImplementationImplementationFeedbackFeedback

End-usersEnd-usersVendorsVendors

RequirementsRequirements

Time:Time: TT11 TT22 TT33 TT44TT55TT00

(N or NN (N or NN yearsyears ))

Requirements/Requirements/Ideas fromIdeas fromusers,users,vendors,vendors,& reseachers& reseachers

Time:Time: TT00 TT11

All standardsAll standards& documents& documents& discussions& discussionsaccessableaccessableelectronicallyelectronically& openly& openlyworldwideworldwideat very lowat very lowcostcost

(N or NN (N or NN monthsmonths ))

IRTFIRTFresearch groupresearch group

IETFIETFBOF groupBOF group

IETFIETFWorking GroupWorking Group

ProposedProposedStandardStandard

ImplementationImplementation++

interoperableinteroperableversions versions

DraftDraftStandardStandard

Single Stage: equirements+development +testing+user implementation feedbackSingle Stage: equirements+development +testing+user implementation feedback

OperationalOperationalexperienceexperience

with real userswith real users

InternetInternetStandardStandardPrototypePrototype

FormattedFormatted& published& publishedon paperon paperwith restrictedwith restricteddisseminationdissemination& high cost& high cost

IETF Standards Making Process

Traditional Standards Making ProcessTraditional Standards Making Process

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21

IETF, IESG, IAB, ISOC

Internet Architecture Board: IAB

� architectural oversight

� elected by ISOC

Internet Engineering Steering Group (IESG): approves standards

Internet Society: ISOC

� conferences

� “hosts” IANA

Internet Assigned Number Authority: IANA

� keeps track of numbers

� delegates Internet address assignment

IETF, IESG, IAB, ISOC

Operational Req. User Services

Security Network Management

Routing Transport

Internet IPng

working group

IESG

DNS srvloc

mobileip

http

avt

WG chair

area director

IETF/IESG chair

IRTF

IAB

IAB chair

IANA

appoints

area

Applications

ISOC president

approves

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IETF

� small focused efforts preferred to larger comprehensive ones

� published goals and milestones

� no formal voting

� disputes resolved by discussion and demonstration (mostly...)

� “Rough consensus (and running code!)”

� mailing list and face-to-face meetings

� open, no-fee membership ($ ATM Forum)

� standardization only after several implementations

� specifications available without charge by ftp ($ ITU, IEEE)

Internet Standards� RFCs

� “Request for Comments”, since 1969

� most RFCs are not standards!

� Internet drafts: working documents, but often used for prototypes

� edited, but not refereed

� numbered sequentially (around 1900 now)

� check the April 1 ones...(RFC 1149)

� ftp://ftp.fokus.gmd.de/pub/rfc/ orftp://ds.internic.net/rfc


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