Networking History

History (1)

• The networks we have today are the result of design decisions made years ago when the computing environment was very different– As these decisions became part of formal or de-

facto standards they became harder to change– An understanding of current network design

therefore benefits from some review of how we got here....

• In the 1940s the term “computer” referred to a person that operated a mechanical calculator!!!

• These calculators became electronic and went through rapid technological change in the 1950s

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History (2)

• These hardware computers became binary-based rather than decimal-based, and generally took on an architecture recognizable today

• By the 1960s a large organization might have a single, room-filling computer– The total number of computers in the world in the

early 1960s was in the low thousands• Probably fewer in number (and less capable) than you

would find today in the cars parked at a large sporting event

– A very large organization might have more than one computer and consider “data communication” between them over phone lines 3

History (3)

• Compiled languages made computers more usable

• User access had the model:– Punch a deck of cards with a program (a “job”) – Submit the deck to the “operators”– Come back later to pick up your deck and the

output – Correct errors in your deck and re-submit

• “Time-sharing” was introduced during the 1960s– Users paid to “dial-up” these large centralized

computers from a terminal using a phone and an “acoustic coupler” • Users interacted directly with the computer for the first

time

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History (4)

• The invention of integrated circuits in 1958 meant that smaller computers were possible – By the latter half of the 1960s the minicomputer

was making computers available to a larger community because of its lower cost

– These were still large, immobile computers but they were only a few equipment racks in size

• The microprocessor appeared in the early 1970s – The Intel 8086 appeared in 1978

• Over 35 years ago, yet backward compatibility in the instruction set is still maintained to some extent in today’s Intel chips

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History (5)

• Although other types preceded it, the IBM-PC of 1981 represents the beginning of the personal computer era for many people

• 1981 also saw the Osborne 1, a “luggable” computer that was actually designed to be moved around

• The late 1980s saw computers that would be comparable in form to today’s laptop computers

• In parallel with this computer development thread there was also a network development thread

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History (6)

• By the early 1970s there were enough large computers at various organizations that networking them together was worth the effort – Many were educational institutions with ARPA

contracts• ARPANET was created using Interface

Message Processors (IMPS) interconnected with 56Kbit serial (phone) lines– The general purpose computer at a site was

connected to the local IMP – The rack of equipment in an IMP was equivalent

to today’s NIC (Network Interface Card) 7

History (7)

• By the mid 1970s development of standardized higher-quality networking protocols and the availability of mini-computers allowed more computers to be interconnected – Universities began building networks local to their

campuses as well as connecting to other universities

– Note how the development of these protocols occurred when computers were still relatively small in number and did not move• i.e., before the large scale use of PCs, and laptops, and

well before tablets and smartphones

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History (8)

• By the late 1970s the NSFNET had been started – This network used the TCP/IP protocol suite from

the beginning – It interconnected a few dozen regional networks,

which were growing rapidly– NSFNET was eventually connected to the original

ARPANET • But the microprocessor-based small

computers of the early 1980s were generally not networked together – Cassette tapes and floppy disks provided data

transfer 9

History (9)

• By the late 80s organizations were connecting their small computers with a variety of vendor-specific protocol suites – Netware, Appletalk, VINES– File sharing within an organization was the

driving force• While the ARPANET and NSFNET had grown

substantially they remained mostly a network for researchers using email, file transfer, remote login and news forums

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History (10)

• In the 90s the development of the Web and the browser finally gave individuals and organizations a reason to connect their computers to a larger network– As more documents were stored online there

arose electronic catalogs for those documents– Documents were delivered by requesting a file

download– A web page primarily added the concept of links

between documents– Later e-commerce, on-line banking, etc. went

beyond the original idea of document retrieval

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History (11)

• This led to a general migration to the TCP/IP protocol suite and to the highly interconnected computing environment we take for granted today– Organizations create private networks for their

internal traffic (often using media they don’t own) – Across a security and administrative boundary

the private network is connected to a larger public network

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History (12)

• Today cloud computing virtualizes an organization’s datacenter as a service (or platform, or infrastructure) available over the network

• In some sense the pendulum has swung back toward the earlier remote computing model with the local device (which could be a mobile smartphone, or tablet, or netbook, or a desktop PC) providing access and a user interface

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