This Session

„ ARPANET as precusor to Internet

Origins of the Internet „ Exploration of heritage from this

„ Origins of TCP/IP and Internet

„ How Internet defeated rivals

I202, Fall 2003 „ Comparison to Open Source Philosophy Session 11 Thomas Haigh (Web and commercialization coming next time…)

i202, Session 10, Thomas Haigh 1 i202, Session 10, Thomas Haigh 2

Origins as ARPANET Early Network

„ Funded by DOD research group ARPA Advanced „ Handrawn diagram of Research Projects Agency APRANET in 1969 „ Built by BBN, an MIT spin-off firm „ Four nodes (“hosts”) „ Each using different kind of „ ARPA funded several computer science teams computer for graphics, HCI, AI, etc. „ Three in CA, plus Utah „ Wanted them to share expensive resources „ Cross country to MIT „ Also wanted to test new networking ideas added in 1970 „ Original function is for remote logins „ 111 hosts by 1977 „ Like Telnet today „ Non ARPA sponsored sites pay up to $100K to connect

i202, Session 10, Thomas Haigh 3 i202, Session 10, Thomas Haigh 4

Actual Applications Shift Key Features Preserved

„ See Abbate readings on this „ Packet Switching „ Official resources (other computers) „ Hard to find (no directory) „ RFC standards process „ Hard to use (no documentation) „ „ Hard to get account on (no incentives or accounting) Separation of Net from Applications „ New applications created over existing infrastructure „ Interconnection of different kinds of „ IMP as LAN hub for local machines „ Email is the surprise hit computer „ Initially runs on top of file transfer protocol „ Science Fiction reviews list & Project Gutenberg

i202, Session 10, Thomas Haigh 5 i202, Session 10, Thomas Haigh 6

1 Interconnection of Separate Net from Applications Different Kinds of Computer

„ Previous networking tended to be multiple dumb „ Code to handle network terminals to one computer traffic is compartmentalized „ No need for application „ Or computer/computer link, coded from scratch programmer to worry about details „ ARPANet includes many different kinds of „ Network code written and computer debugged once only „ „ As purpose is to give remote access to ARPA funded Originally done via hardware research systems, save duplication „ Interface Message Processor or IMP „ Makes standards more important „ Dedicated minicomputer delivered to all installations „ Today done in software „ Net code built into OS i202, Session 10, Thomas Haigh 7 i202, Session 10, Thomas Haigh 8

Packet Switching RFC Process

„ ARPANet was first network to use „ Still basis of modern Internet „ Request For Comment „ Doesn’t establish a circuit for „ Used since 1969 on ARPANet duration of connection „ Become official record of net’s „ Unlike telephone „ Design decisions „ Standards „ Architecture „ Anyone, in theory, can submit proposal „ Contributions are edited and numbered „ Breaks message into many small “packets” „ Currently RFC 3638 is newest „ Each one addressed and numbered „ Each one passed across network separately „ Provide “public” access to protocol specs „ Reassembled when they arrive at destination „ And chance for net community to comment on proposed „ “Dumb network, smart clients” changes

i202, Session 10, Thomas Haigh 9 i202, Session 10, Thomas Haigh 10

TCP/IP TCP/IP: Advantages

„ Current foundation of Internet „ Designed by Vince Kahn and Bob Cerf „ Simple and reliable „ Two protocols: „ Works with different kinds of physical media „ IP = Internet Protocol (packet addressing & transmission) „ Satellites, ethernet, modems, radio, etc. „ TCP = Transmission Control Protocol (retransmission, etc.) „ These are “under” TCP/IP protocol „ Became standard on ARPANet around 1982 „ Can add new media without changing code „ Design and testing from 1975 onward „ Works with many different applications „ Open standard – anyone can use „ DOD backs for military use „ Protocols for news, ftp, etc. run “over” TCP/IP „ Many different firms produce equipment for „ Addition of web, streaming video, etc. needs no changes to TCP/IP or to network

i202, Session 10, Thomas Haigh 11 i202, Session 10, Thomas Haigh 12

2 The Internet Was Spread of Internet

„ Name given to collection of INTERconnected TCP/IP NETworks „ Grew rapidly „ ARPANet (closed in 1990) „ 1984: passes 1,000 hosts „ 1990: 313,000 hosts on 2,063 networks „ NSFNet for scientific use (2000: passes 100 million hosts) „ MILNET for military use „ Opened to commercial use in 1991 (NSFNet) „ Other US and international networks „ Until about 1994, remained mostly for science, „ Bridges constructed to other kinds of networks government, academic use „ Allows interconnection of networks using other „ But became truly global system protocols for internal traffic „ “Gateways” to on-line services, FIDONet, etc. „ Success of TCP/IP means most corporate networks, „ Increasingly popular with students, hobbyists universities, etc. now use internally as well

i202, Session 10, Thomas Haigh 13 i202, Session 10, Thomas Haigh 14

Other Kinds of Networks Rival Philosophy

„ In 1980s, no such thing as “internet service „ OSI project of International Standards provider” Organization „ Access to academics and researchers only „ Need account on connected computer „ Sets up “seven layer model” (see paper) „ So most network users are elsewhere „ Encourages separation of different aspects of „ Other academic networks networking, like TCP/IP but more so „ E.g. BITNET for IBM sites „ Commercial on-line services „ Designs specific protocols for standard use „ Aimed at individuals and small business „ X.25 for packet switching (instead of TCP/IP) „ Amateur bulletin boards „ X.400 for email delivery „ FIDONet links them together for news, email

i202, Session 10, Thomas Haigh 15 i202, Session 10, Thomas Haigh 16

Internet has Similarities Lots of OSI support to Open Source

„ Through early 1990s, seen as future „ Lack of concern with commercial issues „ Standards for protocols reflect long process „ Don’t address concerns of commercial users „ Interests of telecommunication firms „ Standards and information freely available „ Hardware suppliers „ Actual code tends to be shared too „ Try to address „ Start with basic system to solve immediate problems „ Long term needs of „ Gradually expand as needed „ Very wide range of users „ Fix problems as they arise „ Design philosophy is flexible, modular „ So tend to be „ Complicated „ Users are also developers „ Inflexible „ In many cases, at least „ Tied to specific applications and assumptions

i202, Session 10, Thomas Haigh 17 i202, Session 10, Thomas Haigh 18

3 Downsides of Net Philosophy Example 2: Spam „ Internet mail relied on trust, small user pool „ When technology widely used, can be „ Basically, can specify any name, organization, hard to change email address and return address

„ Might have been better to plan more „ Mail is relayed to destination without charge „ No mechanisms to authenticate sender „ Example 1: Running out of IP addresses „ Or prevent tampering, or encode, or recall „ TCP/IP v4 limits number of address numbers message, or acknowledge receipt, or guarantee (4 billion sounds like a lot, but given out in delivery blocks) „ Breaks down in modern world „ Can add some of these features to email clients „ TCP/IP v6 would fix, but adoption is slow „ But would require mass simultaneous adoption „ Might also involve recentralization, loss of privacy

i202, Session 10, Thomas Haigh 19 i202, Session 10, Thomas Haigh 20

4