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Aleksandra Smiljanić [email protected] Introduction
56

Aleksandra Smiljani ć aleks@ieee

Dec 30, 2015

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Aleksandra Smiljani ć [email protected]. Introduction. Uses of Computer Networks. Business Applications Home Applications. Business Applications. Sharing resources Common databases for customer records, inventory, accounts E-commerce Video-conferencing - PowerPoint PPT Presentation
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Page 1: Aleksandra Smiljani ć aleks@ieee

Aleksandra Smiljanić[email protected]

Introduction

Page 2: Aleksandra Smiljani ć aleks@ieee

Uses of Computer Networks

• Business Applications

• Home Applications

Page 3: Aleksandra Smiljani ć aleks@ieee

Business Applications

• Sharing resources

• Common databases for customer records, inventory, accounts

• E-commerce

• Video-conferencing

• Disseminating the information, and coordination

Page 4: Aleksandra Smiljani ć aleks@ieee

Home Applications

• Getting the remote information

• Person-to-person information

• E-commerce

• Entertainment

• E-flea

Page 5: Aleksandra Smiljani ć aleks@ieee

Network Types

• Local Area Networks

• Metropolitan Area Networks

• Wide Area Networks

• Wireless Networks

• Home Networks

Page 6: Aleksandra Smiljani ć aleks@ieee

Network Types

Classification of interconnected processors by scale.

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Local Area Networks

Two LANs(a) Bus-broadcast(b) Ring

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Metropoliten Area Networks

Two MANs(a) Star-switched(b) Ring

Switch

Page 9: Aleksandra Smiljani ć aleks@ieee

Metropolitan Area Networks

A metropolitan area network based on cable TV.

Page 10: Aleksandra Smiljani ć aleks@ieee

Wide Area Networks

Relation between hosts on LANs and the subnet.

Circuit switch

Page 11: Aleksandra Smiljani ć aleks@ieee

Wide Area Networks

A stream of packets from sender to receiver.

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Wireless Networks

Categories of wireless networks:

• System interconnection

• Wireless LANs

• Wireless WANs

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Wireless Networks

(a) Bluetooth configuration(b) Wireless LAN

Page 14: Aleksandra Smiljani ć aleks@ieee

Home Network Categories

• Computers (desktop PC, PDA, shared peripherals)• Entertainment (TV, DVD, VCR, camera, stereo, MP3)• Telecomm (telephone, cell phone, intercom, fax)• Appliances (microwave, fridge, clock, furnace, airco)• Telemetry (utility meter, burglar alarm, babycam).

Page 15: Aleksandra Smiljani ć aleks@ieee

Network Hardware

• Transmission medium

• Transceivers: transmitters and receivers on the point-to-point connections

• Multiplexers, demultiplexers

• Packet and circuit switches

• Bridges

• Routers

• Servers, gateways, management units

Page 16: Aleksandra Smiljani ć aleks@ieee

Transmission Medium

• Air: different frequency bands

• Wires: twisted pairs

• Coaxial cables

• Optical fibers

Page 17: Aleksandra Smiljani ć aleks@ieee

Transceivers

• Transmitters perform modulation and coding to provide efficient and reliable communication.

• Receivers perform the reverse operations.

• Depending on the medium transceivers are electronic devices, antenas, or lasers and photodiodes.

Page 18: Aleksandra Smiljani ć aleks@ieee

Multiplexers and Demultiplexers

• Multiplexers receive multiple lower bit-rate streams of data and according to some rule transmit the higher bit-rate stream of data.

• Demultiplexers do the opposite.

Page 19: Aleksandra Smiljani ć aleks@ieee

Circuit and Packet Switches

• It does not make sense to connect every user with every other user in the network.

• Circuit and packet switches connect multiple inputs to multiple outputs.

• In circuit switches, the configuration pattern changes on a slow time scale.

• In packet switches, the configuration changes on a packet-per-packet basis.

Page 20: Aleksandra Smiljani ć aleks@ieee

Servers, Gateways, etc.

• Servers store various kinds of information for users, for example DNS databases, e-mails, web pages and provide it to the users.

• Gateways convert data format, and negotiate QoS with the network.

Page 21: Aleksandra Smiljani ć aleks@ieee

Layered Structure of Networks

Layers, protocols, and interfaces.

Page 22: Aleksandra Smiljani ć aleks@ieee

Protocol Hierarchies

Example information flow supporting virtual communication in layer 5.

Page 23: Aleksandra Smiljani ć aleks@ieee

Design Issues for the Layers

• Addressing• Error Control• Flow Control• Multiplexing• Routing

Page 24: Aleksandra Smiljani ć aleks@ieee

Services to Protocols Relationship

The relationship between a service and a protocol.

Page 25: Aleksandra Smiljani ć aleks@ieee

Reference Models with Layers

• A layer should have well defined function

• Function of a layer should be internatinationally standardized

• The information flow between interfaces should be minimized

Page 26: Aleksandra Smiljani ć aleks@ieee

Reference Models

• The OSI reference model

• The TCP/IP reference model

• Hybrid reference model

Page 27: Aleksandra Smiljani ć aleks@ieee

Reference Models

The OSI reference model.

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Reference Models

The TCP/IP reference model.

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Reference Models

Protocols and networks in the TCP/IP model initially.

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Comparing OSI and TCP/IP Models

Concepts central to the OSI model• Services• Interfaces• Protocols

Concept of TCP/IP

• Implementation of the required functionality with three layers

Page 31: Aleksandra Smiljani ć aleks@ieee

A Critique of the OSI Model and Protocols

Why OSI did not take over the world

• Bad timing

• Bad technology

• Bad implementations

• Bad politics

Page 32: Aleksandra Smiljani ć aleks@ieee

Bad Timing

The apocalypse of the two elephants.

Page 33: Aleksandra Smiljani ć aleks@ieee

A Critique of the TCP/IP Reference Model

Problems:• Service, interface, and protocol not distinguished• Not a general model• Host-to-network “layer” not really a layer• No mention of physical and data link layers• Minor protocols deeply entrenched, hard to replace

Page 34: Aleksandra Smiljani ć aleks@ieee

Hybrid Model

The hybrid reference model to be used in this book.

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Example Networks• The Internet

• Ethernet

• Wireless LANs: 802.11

Page 36: Aleksandra Smiljani ć aleks@ieee

Example Networks• 1960. Barn from RAND co. first proposal• 1957 Advanced Research Project Agency (ARPA)• 1967 Larry Roberts proposes ARPANET, that was

implemented by BBN co.• Interface Message Processors (IMP) were connected

by 54kbps links. Protocols: host-IMP, IMP-IMP, host-host

• 1969 experimental network, UCLA, UCSB, Stanford University, Yuta University

Page 37: Aleksandra Smiljani ć aleks@ieee

The ARPANET

(a) Structure of the telephone system.(b) Baran’s proposed distributed switching system.

Page 38: Aleksandra Smiljani ć aleks@ieee

The ARPANET

The original ARPANET design.

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The ARPANET

Growth of the ARPANET (a) December 1969. (b) July 1970.(c) March 1971. (d) April 1972. (e) September 1972.

Page 40: Aleksandra Smiljani ć aleks@ieee

TCP/IP Development

• In 1974, TCP/IP model has been established by Cerf and Kahn, and incorporated into Berkeley UNIX.

• Because of the large number of hosts, domain name system (DNS) was created in 1980s.

Page 41: Aleksandra Smiljani ć aleks@ieee

NSFNET

• NSF (National Science Foundation) invested into the network for all universities.

• Backbone included supercomputers at several universities, it is connected to ARPANET at Carnegie-Mellon university.

• MCI rented cables at 448kbps, and IBM provided computers as routers.

Page 42: Aleksandra Smiljani ć aleks@ieee

NSFNET

The NSFNET backbone in 1988.

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Further Development

• 1990 non-profit organization Advanced Networks and Services (ANS) started comercialization, and improved speed to 45Mbps, ANSNET started. In 1995 sold to AOL

• In nineties EuropaNET and EBONE are developed

Page 44: Aleksandra Smiljani ć aleks@ieee

Internet Usage

• Traditional applications (1970 – 1990) – E-mail– News– Remote login– File transfer

• World Wide Web developed by CERN physicist Tim Bernars-Lee, and Mark Andressen at National Center for Supercomputer applications

Page 45: Aleksandra Smiljani ć aleks@ieee

Architecture of the Internet

Overview of the Internet.

Page 46: Aleksandra Smiljani ć aleks@ieee

Ethernet

• Bob Metacalfe graduated MIT and Harvard, and worked on Hawaii on ALOHANET.

• He designed first computer LAN at Xerox Parc in Palo Alto.

• DEC, Intel, Xerox make DIX standard that becomes IEEE802.3

• Metcalfe founds 3Com

Page 47: Aleksandra Smiljani ć aleks@ieee

Ethernet

Architecture of the original Ethernet.

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Wireless LANs

(a) Wireless networking with a base station.(b) Ad hoc networking.

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Wireless LANs

The range of a single radio may not cover the entire system.

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Wireless LANs

A multicell 802.11 network.

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WLAN Issues

• CSMA/CD may not be applicable

• Multipath fading

• Mobility

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Network Standardization

• Who’s Who in the Telecommunications World• Who’s Who in the International Standards World• Who’s Who in the Internet Standards World

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ITU• Main sectors

• Radiocommunications• Telecommunications Standardization• Development

• Classes of Members• National governments• Sector members (AT&T, Cisco, Intel, AOL Time

Warner…)• Associate members• Regulatory agencies (FCC)

Page 54: Aleksandra Smiljani ć aleks@ieee

ISO• 200 Technical Committees, divided into

subcommittees, and working groups involving 100000 voluneers.

• TC97 in charge for computers and information processing.

• American National Standards Institute (ANSI) is US representative in ISO.

• National standards organization -> committee draft ->draft international standard -> standard

Page 55: Aleksandra Smiljani ć aleks@ieee

IEEE 802 Standards

The 802 working groups. The important ones are marked with *. The ones marked with are hibernating. The one marked with † gave up.

Page 56: Aleksandra Smiljani ć aleks@ieee

Internet Standards• In 1983, Internet Activities Board (IAB) was

established.

• Communication was done through “request for comments” (RFC) documents.

• IAB is moved to Internet Research Task Force (IRTF) and Internet Engineering Task Force.

• Proposed standard -> draft standard -> standard