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 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'll refresh 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 ®rewall (the) Internet : ªcollection of networks and routers that spans 61 countries and uses the TCP/IP protocols to form a single, cooperative virtual networkº. (Comer) 6
Internet Actors Started by U.S. research/military organizations:
(D)ARPA: (Defense) Advanced Research Projects Agency ➠ funds technology with military usefulness DoD: U.S. Department of Defense ➠ early adaptor of Internet technology for 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 study computer networking 1968: ARPAnet contract awarded to Bolt Beranek and Newman (BBN) 1969: ARPAnet has 4 nodes (UCLA, SRI, UCSB, U. Utah), connected by IMPs (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: ®rst satellite link from California to Hawaii 1973: First international connections to the ARPANET: England and Norway
1979: ARPAnet 100 nodes
A Short History of the Internet: 1980's
proliferation of local area networks: Ethernet and token rings
late 1980's: ®ber optic networks; ®ber 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: ¯ag day: NCP ! TCP early 1980's: split ARPANET (research), MILNET (military) 1984: Domain Name Service replaces hosts.txt ®le 1986: NSFNET created (56 kb/s backbone) 8
Nov. 1, 1988: Internet worm 1989: Internet passes 100,000 nodes 1989: ®rst 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 150 Mb/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 (ªping'ableº)
IP-connected hosts (SLIP, PPP)
®rewalled hosts
e-mail reachable
ªConsumerº 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 ªmembersº)
T-Online/Datex-J (750,000 in Germany)
lots of small ones or count people with access to services 11
Internet User Populations
firewalled
10 mio.
on-line services widget.com SLIP/PPP
email only core Internet (X.400, FIDO,...)
7.8 mio. 11.5 mio.
INTERNATIONAL CONNECTIVITY Version 14 - 6/15/95 Internet Bitnet but not Internet Copyright © 1995 Larry Landweber EMail Only (UUCP, FidoNet) and the Internet Society. Unlimited permission to copy or use is hereby granted No Connectivity subject to inclusion of This map may be obtained via anonymous ftp this copyright notice. from 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 ® 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
Demand for Global Domain Names Registrations 1,000,000
100,000 Commercial Companies Non-Profit Companies 10,000
Universities 1,000 Network Operators
100 Dec.92 Dec.93 Dec.94 Dec.95 Source: Mike Walsh, NSI
Copyright © 1995 A.M.Rutkowski 13
Internet Growth Two metrics: number of IP-connected hosts, domain names 107
106
105 Total IP connectivity Germany 104 Internet hosts
103
102 80 82 84 86 88 90 92 94 96 98 year
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 Traf®c Report 105
104
103
102
101 Gigabytes/month 100 Total ftp gopher 10−1 WWW email news − 10 2 1991 1992 1993 1994 1995 year
Internet Services January 1995 NSFnet
dns ircX11 gopher 3% 2%1% 4% login 4%
MBONE 5% ftp 31%
email 6%
news 12%
unknown WWW 14% 18% 15
16
Who runs the Internet?
ªnobodyº
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 Access Points), DFN, ...
®bres: telephone companies (mostly)
content: thousands of companies, universities, individuals, ...
Who pays for the Internet?
international NAP lines Internic
national network regional (MCI, Sprint, ...) network
ISPcompany university ISP on-line services 56 kb - 2 Mb log-in via modem shell LAN 17
How is the Internet paid for? Generally: distance-insensitive dial-up: per minute (peak/off-peak) or ¯at monthly direct connection: ¯at rate or volume bands; rarely extra for international bytes; no time zones
$ German telephone: 4 time zones, 4 distance zones, plus international tariffs ➠ may change with reserved bandwidth! 18
Network Access and Interconnection
regional network
NAP NAP company
point-of-presence firewall (POP) R firewall 56kb/s national R - 2Mb/s R R network T3 Ethernet local telephone modem company concentrator
regional network
phone lines+ node
PC
phone telephone modem company switch
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 ®xed $7899/month $26700/month ATM traf®c 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 Of®ce on line yes Btx? computer use (households) 36% 40% equipped with modems 53% 20
The Standards-Making Universe Traditional Model Telco Bodies
ATSS Traditional Model Information OAS International Australian Coordinating CCITT Systems Bodies Organizations ECSA-T1 CSRG EIA/TIA
PCS S1 TR8 X1 ECSA TR41 JATE * TR29 Q1 TR30 NIST Y1 CSA ANSI X3 OIW M1 CEPT SCC BT E1 T5 T1 CBEMA SPS T2 HATS ECMA POSI S3 V1 Conf TTC NA CEN GROUP SPAG RCR ETSI CAC 15 20 T9 29 EWOS CENELEC SIS NA NA 1 CCIR (UP)CCITT NA NA NA TC32 SNV NA C0S EMUG NNI TTC (down) DIN
EDI STDS 26 ITU 1 13 2 83 AFNOR CCITT SC21 24 27 25 TTACCIR 3 4 11 13 10 11 Radio 5 12 18 JTC 23 IEC Conf ITU-T 15 4 6 14 SC6 17 ISO-IEC CCITT 8 2 7 22 11 8 1 ITU 9 REG 7 14 BSI CCIR URSI ITU-R 9 15 6 CTSAC 5 7 2 10 ISO/IEC 1 .8 SMPTE .1 .7 BCS Network .2 802 Managem’t .6 IEEE IETF .3 .5 Forum .4 POSIX B’cast SMDS Unions JISC Interest Internet IANA* PCR* Group ATM Society JSA Forum Traditional EDIFACT X-Windows Open Radio Consortium Software NA Fdn ISDN Users RARE Frame Forum Bodies Microsoft RIPE Relay MAPI Unix Forum EuroFR Int’l SIGMA Forum Group Winsock Group New Model Information X/Open VESA Stds New Model Ass’n Systems Bodies A.M.Rutkowski Telco Bodies copyright 1994
Standards Making Processes Traditional Standards Making Process
Formatted & published Stage 2: on paper Base Standards Stage 3: with restricted Development Profiles/Product Stage 1: Profiles/Product dissemination Initial Development Stage 4: Stage 5: & high cost Requirements Requirements X3 Testing T1 User OIW Implementation CCITT COS Vendors EWOS COS Feedback ISO/IEC JTC1 AOW NVLAP IEEE MAP/TOP EOTC EIT/TIA End-users Vendors Vendors Vendors JTC1/SGFS T0 T1 Consortia T5 Time: T2 T3 T4 (N or NN years) IETF Standards Making Process Proposed Draft Internet Prototype Standard Standard Standard All standards & documents & discussions IRTF Requirements/ IRTF Implementation accessable research group Operational Ideas from IETF + experience electronically users, Working Group & openly IETF interoperable with real users vendors, worldwide BOF group versions & reseachers at very low cost Single Stage: equirements+development +testing+user implementation feedback cost
Time: T0 T1 (N or NN months) 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
ªhostsº IANA Internet Assigned Number Authority: IANA
keeps track of numbers
delegates Internet address assignment
IETF, IESG, IAB, ISOC
IAB chair ISOC president approves IANA IAB
appoints
IETF/IESG chair
IRTF IESG
area area director Operational Req. User Services
Applications Security Network Management http Routing Transport
mobileip Internet IPng
WG chair
DNS srvloc avt
working group 22
IETF
small focused efforts preferred to larger comprehensive ones
published goals and milestones
no formal voting
disputes resolved by discussion and demonstration (mostly...)
ªRough consensus (and running code!)º
mailing list and face-to-face meetings $ open, no-fee membership ( ATM Forum)
standardization only after several implementations $ speci®cations available without charge by ftp ( ITU, IEEE)
Internet Standards RFCs
ªRequest for Commentsº, 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/ or ftp://ds.internic.net/rfc