HSCI1011 - Week 3

Key terms:

• TIP: Terminal Interface systems; customized IMPs for local circumstances

• Illicit links: Connecting to foreign networks

• USING: Activist group of users who sent reports to ARPA making suggestions for the ARPANET

• Time-sharing

• Elizabeth Feinler - oversaw the distribution of the ARPANET “white pages” and “yellow pages",” directories of people and services on the fledgling network

• RFCs: Requests for Comments

• PRNET: Packet Radio Network

• SATNET: Satellite Network

• DCA: Defense Communications Agency

• TCP - standardized protocols for different networks

General notes:

I. Key points from Ch. 1-3

• The building of the ARPANET was a response to various concerns in the second half of the 1960s

  • Ensuring communications during a war

  • Advancing time-sharing techniques to allow more computers to be connected

  • Promoting efficient uses of communications lines

  • Resource sharing

• ARPANET, the predecessor of the Internet, was a product of the military-industrial-academic complex

• ARPANET’s early users contributed greatly to improve the technical environment and directions of development of the ARPANET'

II. Difficulties of early users when accessing the ARPANET in the 70s

• Non-IPTO contractors

  • Price to join - $55,000-$107,000

  • Hardware IMP/TIP

  • Programs took a year to complete

  • AT&T telephone line set up

• Technical barriers

• Incompatibility of computers

• Computer time charged

• “I don’t think any of the hosts were all that easy to use if your weren’t part of the computer community,” (Alex McKenzie 1997)

III. Three aspects of the ARPANET that users’ experiment notably affected

• Terminal interface systems; terminal to ARPANET

• USING pushed new applications such as accounting, editing, and upper-level protocols, some structural level suggestions, but ARPA resisted

• New Communications Paths: Local Area Network; connecting to foreign networks

IV. Terminal interface message processors (TIP)

• Invented by BBN to allow sites without host computers to connect to the ARPANET

• Can connect to more than one host

• Users made their own TIPs

  • Specific local conditions required BBN to revise its hardware and software

  • BBN was tired of these requests

  • Users at local sites decided to do improvements on their own; Roberts eventually also funded local sites to do such improvements

  • ANTS at UIUC connected many peripherals and terminals before the first TIP

V. New Communications Paths

• Local Area Network (intra-node) —— by 1975 almost 30% of ARPANET traffic was intra-node

• Pushed new applications such as accounting, editing, and upper-level protocols, some structural level suggestions, but ARPA resisted

• The development of email

  • The concept and similar mechanism existed in the time-sharing system in the 1960s

  • By mid 1971, several ARPANET sites were experimenting sending messages to a particular computer

  • Before 1973, Ray Tomlinson at BBN wrote the working network mail program to send messages between TENEX machines at ARPANET sites

  • FTP based message transfer was adopted in 1973 til 1980s

  • ARPA director Stephen Lukasik promoted it for the communication between ARPA and contractors

VI. Evaluation of Roberts’s plan to promote more resource sharing

• The hope that ARPANET could substitute for local computer resources was in most cases not fulfilled

• Military resource

• Fewer remote users than expected

• Some centers wanted to make profits

• Software and files sharing was limited

• More and more minicomputers and high-performance computers became available

VII. Conclusion

• User activism - Abate argues that the history of the ARPANET demonstrates that users could shape, change, or revise the design of technology

• While being developed under the military-industrial-academic complex, ARPANET’s early users and designers oriited resources sharing and new modes of communications

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~Ch. 4 - From ARPANET to Internet

I. Overview

• The growing inter-networking

  • ARPA supported the construction of new networks such as PRNET (packet radio) and SANET (satellite)

  • Military concerns prompted the technical innovations for the internetworking

• Military management of ARPANET

  • Defense communications agency (DCA)’s management of the ARPANET (1975-1983) v. ARPA’s management of the ARPANET (1968-1975)

II. The internet (inter-networking) Program

• Land-based: ARPA

• Packet Radio Network: PRNET

• Satellite network: SATNET

• Connected through TCP

III. Two origins of Packet Radio transmissions——PRNET

• Alohanet

  • U of Hawaii explored packet switching via radio channels to replace costly dial-up telephone lines

  • “Random access” method to ensure all users can share a broadcast channel without interfering with each other

• Bob Kahn

  • Left BBN to direct ARPA in 1972

  • Began pursue inter-networking projects to attract defense-related funds

    • Radio terminals could be mobile—-ideal for military field operation

• Prototype: PRNET—-packet radio network for San Francisco Bay Area (1975~)

  • Packet Radio Van (a radio equipped van)

  • Repeaters

  • Radio sets that can be connected to computers

• SATNET in 1973

  • Experiments connected sites between US and Europe

  • Seismic monitoring program

  • Same testings in `1977 conducted in military counterpart

IV. Military’s Management of ARPANET

• Transition of power

  • AT&T rejected invitation to manage ARPANET commercially

  • DCA took operational responsibility in 1975

    • Began to use ARPANET in an extensive way

    • Split network into a public “ARPANET” and classified “MILNET”

      • Only 45 hosts remaining

  • NSFNET took over ARPANET in 1988

  • NSFNET lifted commercial use in 1991

  • ARPANET terminated in 1990

• New culture

  • Contracts through bureaucratic channels instead of informal

  • Policing frivolous activities such a file copying without consent and email chain letter

  • Limiting unauthorized users

  • DCA used to consider dismantling the ARPANET, since AUTODIN II worked for military sites

  • Rushed transition from NCP to TCP/IP

V. Main questions Ch. 4

• DCA took over ARPANET in 1975—-how did they manage it differently?

• Do computer networks inherently promote decentralized forms of communication? Does the networking of computers always promote collaborations? Compare and contrast the different management of ARPA and DCA over the ARPANET

• What do you think are the most important factors AND why are these factors important?

VI. TCP/IP

• Original ARPANET protocol was NCP—wasn’t good at error-recovery mechanisms

• 1977 TCP/IP demonstration was a success

• Vinton Cliff split TCP into two parts

  1. Transmission Control Protocol (TCP): Host-to-host protocols

  2. Internetwork protocols (IP): Passed individual packets between machines fom host to packet switch or between packet switches

• DCA forced switch to TCP/IP from 1981-1983

Conclusion (ch. 4)

• The origins of the ARPANET and the Internet were heterogeneous

  • Military & civilian concerns, research ethos of universities powered by ARPA fundings, etc.

• Inter-networking breakthroughs from 973-1983 were pushed for military application under DCA. DCA even briefly considered dismantling ARPANET (1978)

• Interworking breakthroughs had unplanned contributions to local-area networking: creation of TCP/IP, and civilian uses of the various networks