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An introduction to computer networks, their history, types, and motivations. It covers wans (e.g., arpanet, internet) and lans (ethernet, fddi, novell netware, appletalk, wireless), as well as other networks like telephone, cable tv, satellites, man, san, and pan. The document also discusses connectivity, link types, and switched networks (circuit-switched and packet-switched).
Typology: Study notes
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-- Chinese Blessing (or Curse) The Industrial Revolution (c. 1760) The change in social and economic organization resulting from the replacement of hand tools by machine and power tools and the development of large-scale industrial production. The “Digital Revolution” (c. 1990) The change in social and economic organization resulting from the replacement of earlier forms of communication and information storage by a digital format and the development of large-scale networks transmitting digital information.
net·work (net´würk´) n. 1. any arrangement or fabric of parallel wires, threads, etc. crossed at regular intervals by others fastened to them so as to leave open spaces; netting; mesh 2. a thing resembling this in some way; specif., a) a system of roads, canals, veins, etc. that connect with or cross one another b) Radio and TV a chain of transmitting stations controlled and operated as a unit c) a group, system, etc. of interconnected or cooperating individuals 3. the making of nets or netted fabric
Defn : A computer network is a collection of computers interconnected via a transmission medium (e.g., copper wire, optical fiber, microwaves, satellites, etc.) The computers are usually general-purpose programmable hardware devices.
Allow humans to communicate through email, telephone, teleconferencing, etc.
WANs (c. 1970) Driving force: The need for government and university researchers located in various parts of the United States to communicate ideas and data between computers. Examples: ARPANET was created in the early seventies Funded by ARPA (DARPA) Prototype for what has evolved into the Internet Created by folks from Berkeley, MIT, AT&T Bell Labs, etc. LANs Driving force: The creation of the personal computer in the mid- 70s and its widespread usage in the mid-80s. Evolution:
Two types of switched networks:
Header overhead (i.e., the amount of "extra" information that must be sent along with the data to ensure proper transmission) For large amounts of data: circuit switching <= packet switching Transmission delay (i.e., the amount of time it takes data from the time it enters the network until it arrives at its' destination) For short and bursty messages: packet switching has the lowest delay.
For long, continuous streams of data: circuit switching has the lowest delay.