Week 03 - OS, Applications, Networks

LECTURE 4 - COMPUTER NETWORKS

Computer Networks

Networks allow automated communication directly between computers, rather than human-computer communication. Developed in the 1950s, became mass-market with the growth of the Internet in the 1990s.

Local networks - typically Ethernet hardware

Network hardware runs software network protocols

Internet protocol (TCP/IP) - public domain
Proprietary networks
- Novell Netware
- Microsoft Windows Networking
- AppleTalk
- Cellphone Internet connections (WAP)

Extended networks (including Internet, wireless links)

Connecting to a network


Cable modems - Internet signal sent via cable network	DSL modem - Internet signal sent via phone lines

Local Internet routers (wired and wireless) with firewall	Bluetooth - ultra short-range wireless network http://www.bluetooth.com/bluetooth

Wi-fi - short-range wireless network http://www.wi-fi.org/OpenSection/index.asp	Wimax - long-range wireless connecting short-range WiFi http://www.wimaxforum.org/home/

Origin of the Internet (1969)

The "Victorian Internet" - the 19th century telegraph system was digital, and more similar to the Internet than the phone system which replaced it
SAGE - early version of networked computers used by the military in the 1950s (see above)
"Fail-Safe" movie - heightened consciousness of vulnerability of SAGE and other centralized computer networks to breakdown.
Packet-switching - developed at MIT and RAND corporation - way to route data through unreliable networks
Robert Taylor - proposed directly connecting computers together into a network (could get to multiple computers from one terminal/keyboard. Applied (KEY IDEA: "packet switching" technology)
http://www.pbs.org/opb/nerds2.0.1/networking_nerds/taylor.html
First generation of Internet developed by DARPA (Defense Advanced Projects Research Agency) hired UC professors, BBN to create a computer network that could survive an atomic war.
http://www.computerhistory.org/exhibits/internet_history/index.shtml
Labor Day 1969 - first messages set using Internet-style packet switched network.
http://www.pbs.org/opb/nerds2.0.1/networking_nerds/fournodes.html

Interface Message Processor - proto-Internet router, allowed any computer to connect to ARPANET computers, beginning of the Internet.
http://www.livinginternet.com/i/ii_imp.htm


An early ~1970 ARPANet router	Another image of early Internet router

Early Internet Structure (1971, about the time email was invented)

Historical maps of the Internet's growth
http://www.cybergeography.org/atlas/historical.html

Invention of email (1972)
http://www.livinginternet.com/e/ei.htm

Invention of Usenet (1980, first online discussion board
http://www.faqs.org/faqs/usenet/what-is/part1/

Usenet today - Google Groups
http://groups.google.com

Invention of World-Wide Web (1990)
http://www.boutell.com/newfaq/history/inventedweb.html


Tim Berners-Lee inventor of the world-wide web	Marc Andreessen - developer of first graphical web browser (Mosaic), co-founder of Netscape

Early web browsers


NCSA Mosaic (1993) developed by Marc Andreessen http://www.livinginternet.com/w/wi_mosaic.htm	Netscape (1994) the first "commercial" web browser, launched the 1990s "dotcom" boom

1990s - Dotcom and Dot-Bom era
http://www.amazon.com/gp/richpub/listmania/fullview/14FSK1KGZSAR4/102-7071737-9384147?%5Fencoding=UTF8


Kaleidospace (now indiespace.com) - art/music sales Jan 1994	Yahoo! in 1996, when you could still add your own URL for free

Recent Internet growth - slowing to a stop in the 2000s, but demand for "rich media" rising


Growth of Internet users (slowing rapidly)	Growth of bandwith (continuing to rise)

Internet traffic growth slows by 50% in 2005
http://www.telegeography.com/press/releases/2005-08-23.php

Proposed Interplanetary Internet (only hypothetical, delay times will cause problems)

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