© MMII JW Ryder

CS 428 Computer Networks

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Motivation for Internetworking

• Most networks are independent entities

• Networking is old idea

• Internetworking is more than 25 years old– Heterogeneous interconnect

networks– Network hardware details hidden

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CS 428 Computer Networks

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Open Systems Interconnection

• Open System = Publicly available specifications

• Proprietary Communication systems = One vendor, self-serving

• Our network benefits from OSI standards

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CS 428 Computer Networks

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OSI Why?

• “More importantly, the entire technology has been designed to foster communication between machines with diverse hardware architectures, to use almost any packet switched network hardware, and to accommodate multiple computer operating systems.” Doug Comer, page 1

• Would that the world were so were so facile.

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CS 428 Computer Networks

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TCP/IP Internet

• Advanced Research Projects Agency (ARPA)– Defense Advanced Research

Projects Agency (DARPA) in mid-80’s

• ARPA technology defines a set of network standards that specify how computers communicate

• Set of conventions for interconnecting and routing

• At one point, all addresses were kept in a single file

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CS 428 Computer Networks

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TCP/IP

• Standards & conventions called Protocols

• TCP/IP is a blend of Transmission Control Protocol and Internet Protocol

• TCP/IP Internet Protocol Suite

• Across any set of interconnected networks

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TCP/IP

• Forms base for a global internet

• An internet = private internets that use TCP/IP

• The Internet = The Global Internet

• Many U.S. gov’t agencies have funded the Internet development

• The ARPA/NSF Internet– The TCP/IP Internet– The global Internet– The Internet

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• To user, TCP/IP appears to be a set of application programs

• Interoperability - the ability of diverse computing systems to cooperate in solving computational problems

• Internet application programs demonstrate a high degree of interoperability

Application Level Internet Services

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• Electronic mail

• File transfer

• Remote login

Applications

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• Programmer’s view provides 2 broad services

• Connectionless Packet Delivery System

• Reliable Stream Transport Service

Network Level Internet Services

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What Distinguishes TCP/IP?

• Network Technology Independence– Datagram

• Universal Interconnection– Addresses universally recognized

throughout the Internet

• End to End Acknowledgements– Others are just between stations

(intermediate routing nodes)

• Application protocol standards

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History & Scope of the Internet

• ARPA began internet technology in mid-70’s– Architecture & protocols taking

current form ‘77-’79 (ARPANET)

• Point to Point leased line interconnection, radio networks, satellites

• Funding $$$ prevalent in ‘79, many researchers

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CS 428 Computer Networks

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ICCB

• Internet Control and Configuration Board

• ARPA formed informal committee to coordinate – Design of protocols– Architecture

• Met through about 1983

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Global Internet

• Began around 1980• ARPA started converting

machines attached to its research computers with TCP/IP

• ARPANET became the backbone of new Internet

• January 1983 Office of Secretary of Defense mandated that all computers connected to the long haul network use TCP/IP

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CS 428 Computer Networks

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ARPANET/BSD/BBN• Split, 1 for research, 1 for military research

• Made ARPANET available to universities at low cost

• At time, most CS departments were using Unix

– University of California’s Berkeley Software Distribution, Berkeley Unix, BSD Unix

• ARPA funded Bolt Beranek and Newman (BBN) to implement its TCP/IP protocols for use with Unix

• ARPA funded Berkeley to integrate the protocols with its software distribution

• Ergo, ARPA able to reach very high percentage (90%) of all university CS departments

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BSD Unix

• Offered a set of networking functions that resembled Unix services used on single machines

• Experienced Unix users have no problems learning TCP/IP networking interfaces because they are so similar

• New operating system abstraction called the socket– Allows application programs to

access communications protocols

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CS 428 Computer Networks

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Internet Youth• 1985 - Six supercomputer centers• 1986 - Expanded to funding wide

area backbone called NSFNET• Tied above to ARPANET• NSF in 1986 provided seed money

for regional networks• All NSF funded networks use

TCP/IP• 1987 (7 years later) the Internet

spanned hundreds of individual networks in the U.S. and Europe

• Connected nearly 20.000 computers, by late 1987 estimate was that the Internet was growing at 15% per month

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CS 428 Computer Networks

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Internet Teenager• 1994 - the Internet reached over

3,000,000 computers in 61 countries

• Rapid expansion problems of an unanticipated scale

• Motivated researchers to find techniques to manage large, distributed resources

• Original design– Names and addresses of all

computers attached to the Internet were kept in 1 file

– Mid-80’s apparent central data base not right solution

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CS 428 Computer Networks

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Domain Name System

• Name servers answer queries about name/address pairs

• No single machine contains entire name base

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Internet Architecture Board (IAB)

• TCP/IP internet protocol did not arise from a specific vendor or from a recognized professional society

• Who sets the technical standard?

• The IAB provides focus and coordination for– Research– Development– Guides Evolution– IAB is almost exclusively

volunteers

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IAB Activities

• Formed in 1983 from reorganized ICCB

• First 6 years, it changed from ARPA specific to autonomous organization

• Each member of IAB chaired a specific Internet Task Force– Approx. 10 task forces– Charters from how traffic load

from an application affects the Internet to short term Internet Engineering problems

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IAB Activities• Did not manage a large budget

• Volunteers

• Members responsible for recruiting volunteers to serve on task forces– usually from research

organizations of industry where TCP/IP was used

• Active researcher participated because– Serving on task force allowed

learning about new research problems

– Could have direct influence on standards

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CS 428 Computer Networks

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IAB ReOrg

• Summer 1989

• Political and Commercial realities

• Researchers moved from IAB Board to subsidiary group

• New IAB Board with representatives from wider community

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IAB Organization

area 1 area n

IESGIRSG

The BoardIETFIRTF

Research Groups Working Groups