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Outline A. Historical Overview 1961 - 1968: Pre-history 1969 - 1973: ARPAnet research period

The First 31 Years of the Internet -- An Insider’s View. Bob Braden USC Information Sciences Institute Oct 4, 2002. 2. Outline A. Historical Overview 1961 - 1968: Pre-history 1969 - 1973: ARPAnet research period 1974 - 1983: Internet Research Period

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Outline A. Historical Overview 1961 - 1968: Pre-history 1969 - 1973: ARPAnet research period

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  1. The First 31 Years of the Internet -- An Insider’s View.Bob BradenUSC Information Sciences Institute Oct 4, 2002 2 Braden 32 yrs Oct 02

  2. Outline • A. Historical Overview • 1961 - 1968: Pre-history • 1969 - 1973: ARPAnet research period • 1974 - 1983: Internet Research Period • 1984 - 1990: Academic Internet Period • 1990 - ??: Commercial (and Popular) Internet • B. The Internet Architecture • Protocols • Principles • C. Conclusions and Challenges Braden 32 yrs Oct 02

  3. 1961 - 1968: Pre-History • Computers: • Mainframes (mini-computers beginning). • (Discrete) transistors had just replaced tubes. • Data unit was a word of 8, 9, 12, 15, 18, 24, 32, 36, 48, 60 ... bits. Uniform 8-bit bytes were introduced in 1965. • Computer communication? • Why? What would my IBM mainframe SAY to your Univac mainframe??? • Too expensive to lease telephone lines. • The context -- Flower children, JFK & LBJ, the Vietnam War ... Braden 32 yrs Oct 02

  4. 1961 - 1968: Pre-History of Computer Communication • MIT: • J. C. R. Licklider: Memos on "Galactic Network", 1962 • L. Roberts: Plan to build a computer network, 1967 • Rand Corp. • Paul Baran invented packet switching as a concept • NPL (UK): • o Donald Davies & Roger Scantlebury wrote paper on a packet-switching network, 1967 • IRIA (France):o Louis Pouzin – Cyclades network Braden 32 yrs Oct 02

  5. 1969 - 1973: ARPAnet Research Period • ARPA: Advanced Research Projects Agency • A DoD agency formed post-Sputnik to fund long-range research of ultimate importance to the military. • The ARPAnet: • ARPA selected Bolt, Beranek, and Newman (BBN) to design, build, and operate a prototype packet-switching network, the ARPAnet. • Host Computers: • ARPAnet software was developed by university researchers, funded by ARPA. Braden 32 yrs Oct 02

  6. Packet Address Data • Packet Switching • Break data into small packets, each of which carries its own address. Packets of different users are interlaced (“multiplexed”) on e.g. a leased telephone line. • Build a network of "packet switches" • Each switch receives, stores, and forwards packets. • Packets are forwarded hop-by-hop, from any source host computer to any destination host computer. Braden 32 yrs Oct 02

  7. Packet-Switching (cont) • ARPANET packet switches ("IMPs") • Minicomputers • High-speed leased lines (56Kbps) • Distributed adaptive routing algorithm • The ARPAnet grew from 10 hosts to ~ 200 hosts. • Mixture of research and DoD production nodes • Included most major research universities & labs Braden 32 yrs Oct 02

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  11. ARPAnet Protocols • IMP-IMP Protocol: • Reliably deliver a message (packet) of up to 8000 bits to a specified destination host. • Bit orientation to handle different word lengths of hosts. • Using this IMP-IMP service, create a: • Host-Host Communication Service: • Network Control Protocol or NCP. • Using this host-host service, can create: • User Application Services • File transfer, remote terminal login, and email Braden 32 yrs Oct 02

  12. ARPAnet Protocols • Network Control Protocol (NCP) -- why? • IMPS only connect computers, but it is really programs that talk to each other. • NCP can establish multiple logical data streams (“virtual circuits” or “connections”) between a pair of hosts. • NCP opens and closes these connections. • NCP provides flow control on each connection, to prevent overruning receiver application. • NCP establishes an appropriate byte size on each connection. Braden 32 yrs Oct 02

  13. ARPAnet Protocol Stack FTP File Transfer User Protocols Telnet Virtual TTY Terminal NETRJS Remote Job Entry SMTP Email Host-Host Protocol (“NCP”) IMP-host Protocol Braden 32 yrs Oct 02

  14. Legacy of ARPAnet Period • oDemonstrated packet switching technology • oMany new ideas... • -- Protocol Layering • -- Packet voice • -- Email • -- Link state routing protocols • -- Connections (“virtual circuits”) o Reliable, flow-controlled; requires state setup. • -- Datagrams [Pouzin, <1974] o Single packet sent with minimum overhead o Unreliable • -- Presentation Layer [Postel & White @ SRI] • -- RPC (Remote Procedure Call) Braden 32 yrs Oct 02

  15. Internet Research Period: 1974-1983 • By 1974, other packet-switching technologies had been developed or were planned: • Local Area Networks (LANs): Ethernet • Packet Radio network (packet switch+radio: now called “ad hoc wireless”) • Packet-satellite network (SATNET) • DoD's problem: how to hook them together?? • Solution: a network of networks -- an INTERNETWORK. Braden 32 yrs Oct 02

  16. Internet: A Network of (Sub-) Networks INTERNET Host Host packet subnet subnet R R R R R subnet Router [gateway] Hosts Braden 32 yrs Oct 02

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  18. Internet Research Period: 1974-1983 • Seminal paper: "A Protocol for Packet Network Interconnection", Vinton G. Cerf and Robert E. Kahn,IEEE Trans Comm., com-22, no. 5, May 1974. • ARPA funded Internet R&D Program 1976 – 198x • Developed Internet protocol suite ("TCP/IP") • Application layer: TCP/IP versions of ARPAnet application protocols Telnet, FTP, SMTP • ARPAnet cutover to new Internet protocols TCP/IP:January1, 1983 (Orchestrated by Jon Postel, ISI) Braden 32 yrs Oct 02

  19. Foundation Internet Technical Documents • IP RFC 791 • ICMP RFC 792 • TCP RFC 793 • Telnet RFC 764 • FTP RFC 765 • SMTP RFC 788 • Name Server IEN 116 • Assigned Numbers RFC 790 • Although many contributed, these all bear Jon Postel’s name. Braden 32 yrs Oct 02

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  21. 1984 - 1990: Academic Internet • ONSF began to fund Internet growth through NSFnet and CSNET, bringing the Internet to US higher education. • o Higher line speeds: 56 Kbps -> T1 (1.5Mbps) lines • o Exponential growth => repeated growth crises Braden 32 yrs Oct 02

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  23. Important New Protocol Technology • Domain Name SystemMap host names => IP addresses • e.g., "slime.usc.edu" -> 32-bit IP address • Later became the basis for URLs and the Web. • Two-level routing hierarchy: divide into domains • IGPs (Interior Gateway Protocols) route within domains[think area codes], plus: • BGP (Border Gateway Protocol) to route among domains • Solution to congestion collapse: Van Jacobson • Network management: SNMP Braden 32 yrs Oct 02

  24. 1984-1990: Who Ran the Internet? • OUS government agencies: NSF, ARPA, DOE, NASA, had an important influence.(DADDY WAS STILL PAYING...) • o Technical steering committee: a junta of Internet researchers, the Internet Activities Board (IAB). • -- Set up by ARPA (Vint Cerf) ~1980 to advise on research program • -- Until 1993, approved all Internet protocol standards. • -- Created a set of Task Forces led by IAB members (1983) • -- ONE of these task forces grew into the Internet Engineering Task Force (IETF), which today sets the Internet protocol standards. • 3 IETF meetings per year, 2500 people, 100 working groups. Braden 32 yrs Oct 02

  25. Who Runs the Internet Today? • At no time has the entire Internet been run by one organization, nor is this likely to ever happen. • The Internet is not brought to you by the phone company or by a government or by the UN or by Microsoft. • There is no precedent for a global infrastructure built of thousands of separately controlled/administered pieces. • It was designed to work that way, more or less; but it’s still a minor miracle. Braden 32 yrs Oct 02

  26. 1990 - Now: Commercial Internet • Government funding replaced by commercial enterprises -- ISPs • HTTP and the WWW were invented (~1993) and rapidly became the dominant application. • PCs became the dominant hosts • Exponential growth accelerated! • Huge increase in speed and capacity. • The Internet became part of society. Braden 32 yrs Oct 02

  27. 1990 - Now: Stresses on the Protocols • o Growth crisis: 32 bit IP addresses ran low • => developed IPv6 with 128-bit host addresses • o Routing problems: • scaling, stability • o New protocols and algorithms were developed-- Mobile IP-- Security-- QoS • -- Traffic Engineering Braden 32 yrs Oct 02

  28. The Internet Architecture: • Outline • Internet Protocol Stack • "Architecture" -- Fundamental design principles • -- Guide specific engineering decisions, e.g., protocol design • -- Want them simple and general => elegant Braden 32 yrs Oct 02

  29. Internet Protocol Stack • > Applicationlayer -- same as on ARPAnet • > Internetwork Layer:IP (Internet Protocol) • -- Controls end-to-end forwarding of packets by routers. • -- Uses globally-unique IP addresses • -- “Best effort” service: packets may be lost, duplicated, reordered. • > TransportLayer • -- Enhances host-host service; e.g.,TCP provides reliable full-duplex byte streams. • >Link layer: particular subnet protocol. Braden 32 yrs Oct 02

  30. Internet ("TCP/IP") Protocol Stack Application Layer Telnet FTP SMTP … HTTP POP3 … ... UDP TCP Transport Layer IP [Inter]network Layer Link Layer ... Ethernet SONET BBN1822 PPP ATM IP protocol: > plays a unique role as the universal Internet protocol -- “common bearer service”. > Very simple, so routers can be very fast > Minimal service assumptions, so Internet can adapt to new applications and new technologies. Braden 32 yrs Oct 02

  31. Internet Architecture: Deep Assumptions • o Packet switching • -- Unit of data is a packet • -- Packets are statistically muxedBecause computers don’t hum to each other, they CHATTER! • I.E., computer communication isfundamentallybursty. • o Strict protocol layering • -- Successive layers of functional abstraction • -- Headers added/removed in strict LOFO order -- • “Stack”model. • o Goal is universal interconnectivity Braden 32 yrs Oct 02

  32. Architectural Requirements • o Generality • -- Support ANY set of diverse applications, -- Either datagrams (think video) or VCs (think web). • o Heterogeneity • -- Interconnect ANY set of network technologies • o Robustness • -- More important than efficiency • o Extensibility • -- More important than efficiency • o Scalability • (A later discovery. How many ARPAnets could the world support? A few hundred, maybe… ?) Braden 32 yrs Oct 02

  33. The End-to-End Principle • Foundation of the Internet architecture: • Dumb network,smart end systems. • (Exact opposite of telephone network!) • o Dumb networks: only least common service-- Datagram service: no connection state in routers • -- Best effort: all packets treated equally. • o Smart hosts: • -- Maintain state to enhance service for applications. • -- “Fate-sharing”-- If a host crashes and loses comm state, • applications that are communicating share this fate. Braden 32 yrs Oct 02

  34. Fundamental Differences… • o Philosphical gap between Computer Scientists and telecommunication engineers: • > Engineers: "The Internet is under-engineered --it is not optimal or completely predictable or controllable. • (And we like complexity.)" • > Internet Researchers: "Optimal is NOT the point. • The future adaptability of the Internet to new technologies and to new services require that we NOT over-engineer the Internet! Uncertainty and suboptimality: live with it! (And we like generality and simplicity.)" Braden 32 yrs Oct 02

  35. Conclusions • The Internet survived and prospered ... • o It survived a series of real (and imaginary) threats over the years. • -- X.25 • -- FAX (opposing email) • -- Many competitors from industry & government -- e.g., XNS, DECNET, BITNET, MFENET, … • -- Unimaginative government bureacrats • -- ISO Open Systems Interconnect (OSI) • CLNP, TP4, FTAM, … • -- ATM • o Exponential growth is a mighty engine, and vendors and ISPs have been running to keep up. Braden 32 yrs Oct 02

  36. Why did the Internet Succeed? • 1. Leadership from a handful of visionaries • Larry Roberts (ARPA) Vint Cerf (ARPA) Bob Kahn (ARPA) Steve Wolff (NSF) • 2. ARPA-funded BSD Unix development used TCP/IP • --Publicly funded OS --> many vendor products • -- A generation of students used it and then graduated • 3. Triumph of the startups • -- Small companies were agile and creative Braden 32 yrs Oct 02

  37. Why ... (cont'd) • 4. Military concern for "robustness" led to the easily- • deployed IP protocol.o “Plug-and-play” -- populist model fueled growth • 5. Silicon- and Fiber-revolutions were perfectly timed. • 6. The Web popularized the Internet. • 7. Universal interconnection really is a powerful vision. • 8. The Internet architecture provided the generality and extensibility to survive the past and the present. Braden 32 yrs Oct 02

  38. The Future… is fuzzy. • o Economic, business, and political forces are now centralThe Internet ~ railroads in 1882 • Increasingly, large companies ruleo Will ISP mergers lead to monopoly?o Will the telephone companies rule after all?o Will Email survive spam? • o Will spam, viruses, hostile attacks fatally threaten the grand vision of universal interconnection? • o Will the Internet fragment into disconnected pieces? • Incompatible pieces? • o Will censorship take over the Internet? Braden 32 yrs Oct 02

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