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1
Internet: Technology, Protocols and Services
Henning ScbulzrinneGMD Fokus, Berlin
TU Berlin, WS 1995/96
c 1995, Henning Schulzrinne
Credits
� A.M. Rutkowski, Internet Society
� Jim Kurose, University of Massachusetts
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, ...)
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
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.
5
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)
6
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
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)
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)
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 ��������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������
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
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
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
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
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%
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
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!
18
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 ��������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������
19
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%
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
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
22
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