Datacom module 1: Introduction to Data Communications

ECE 521FData Communications

ECE 521F (Data Communications)ECE @Saint Louis University, Baguio City 1

Prepared by: Engr. Jeffrey Des B. Binwag

Course Outline• PRELIMINARY PERIOD

– Introduction to Data Communications

– Data Communications Circuits

– Serial and Parallel Data Transmissions

– Overview of Networking Issues, Network Architectures, and Protocol Architectures

– The Open Systems Interconnection

– QUIZ 1

– Data Communications Codes

– Error Control Codes

– Data Terminal Equipment, Framing, and Synchronization

– Serial Interfaces

– Data Communications Equipment

– QUIZ 2ECE @Saint Louis University, Baguio City 2

Course Outline• MIDTERM PERIOD

– Introduction to Data Link Protocols– Data Link Protocols

• Character-Oriented Protocols• Bit-Oriented Protocols• Asynchronous Data Link Protocols• Synchronous Data Link Protocols• SDLC and HDLC

– QUIZ 3– Introduction to Switched Circuits– Circuit Switching and Packet Switching– Local Area Networks, Applications, and Architectures

• Ethernet• Ring• Token Ring• FDDI

– QUIZ 4

ECE @Saint Louis University, Baguio City 3

Course Outline• FINAL PERIOD

– Local Area Networks and Interconnections• Repeaters

• Bridges and Switches

• Routers and Gateways

– QUIZ 5

– The Internet• Overview of the Internet

• The Internet Protocol

• Domain Name Systems

• Internet Protocol Over Internet

– QUIZ 6


Course Requirements• Quizzes

• Groupworks

• Homeworks

• Exams

• 60% Class Standing Scores– Quizzes, Groupworks, Homeworks

• 40% Exam Score

• Term Grade= 50 + 30(CS)/TCS+20(Exam)/Exam Total

• FG=(PG+MG+TFG)/3ECE @Saint Louis University, Baguio City 5

Grading System


21 3

4 cm

3 cm2 cm

2 cm

3 cm

2 cm

Page Format(for homeworks/ seatworks)

• Computer printout• Margins in red ink• Text in black ink• Section 1 contains the

• Subject• Schedule• Room

• Section 2 contains the names of group members in two columns

• Section 3 remains blank for scores/remarks

• Font is Arial, 12 pt.• CONTENTS

• Homework Title/ Coverage• Answers to Questions/

Solutions to Problems• Essential Learning Insights

Module 1Introduction to Data

Communications

Chapter 21

Electronic Communications Sytems , Fifth Editon

By: Wayne Tomasi

ECE @Saint Louis University, Baguio City7


Introduction• Data Communications. The transmission, reception, and processing of

digital information.• Data. Information that is stored in digital form. Information that has

been, processed, organized and stored.• Data Communications Network. Systems of interrelated computers

and computer equipment connected through the public telephone network or similar network infrastructure.

Any system of computers, computer terminals, or computer peripheral equipment to transmit and/or receive information between two or more locations.

• Network. A set of devices, nodes, or stations interconnected by media links.

• Internet. A public data communications network used by millions of people worldwide to exhange business and personal information.

• Intranet. Private data communications networks used by many companies to exchange information among employees and resources.

• Worl Wide Web (WWW). A server-based application that allows subscribers to access the services offered by the Web.


Data Communication Network Example: Public Switched Data Networks (PSDN)


History of Datacom• 1753. One of the earliest means of communicating

electrically coded information through a 26 wire system.

• 1833. Carl Friedrich Gauss developed a system based on a 5x5 matrix representing 25 letters.

• 1832. The telegraph (the first data communication system) was invented by Samuel F.B. Morse.

• 1840. The American patent for the telegraph was granted.

• 1844. The first telegraph line was established between Baltimore and Washington D.C. conveying the first telegraph message “What hath God wrought!”


History of Datacom• 1849. The first slow-speed telegraph printer was

invented.

• 1850. Western Union Telegraph Company was formed in Rochester, New York, for the purpose of carrying coded messages from person to another.

• 1860. “High-speed” printers (15 bps) became available.

• 1874. Emile Baudot invented the a telegraph multiplexer that allowed signals from up to six different telegraph machines to be transmitted simultaneously over a single wire.

• 1875. The telephone was invented by Alexander Graham Bell.


History of Datacom• 1899. Guglielmo Marconi succeeded in sending

radio (wireless) telegraph messages. • 1920. The first commercial radio stations

carrying voice information were installed.• 1930s. Konrad Zuis, a German engineer,

demonstated a computing machine.• 1940. Bell Laboratories developed the first

special purpose computer using electromechanical relays for performing logical operations.

• 1946. The first modern-day computer (ENIAC) was developed by J. Presper Eckert and John Mauchley at the University of Pennsylvania.


History of Datacom• 1949. The U.S. National Bureau of Standards

developed the first all-electronic diode based computed capable of executing stored-programs.

• 1950s. “Batch processing” computers used punched cards as an input interface, printers as an output interface, and magnetic tape reels for data storage.

The first general purpose computer in the form of an automatic sequence-controlled calculator was developed jointly by Harvard University and IBM Corporation.

• 1951. Remington Rand Corporation built the first mass-produced electronic computer (UNIVAC).


History of Datacom• 1960s. Batch-processing systems were replaced

by on-line processing systems with terminals connected directly to the computer through serial or parallel communication lines.

• 1968. The landmark US Supreme Court Carterfone decision allowed non-Bell (non AT&T) equipment to be connected to the vast AT&T network.

• 1969. The internet began to evolve at the Advanced Research Projects Agency (ARPA) through the ARPANET.

• 1970s. Microprocessor-controlled microcomputers were developed.


History of Datacom• 1980s. Personal computers became an essential

item in the home and the workplace. Since then, the need to exchange digital information, and consequently, the need for data communication circuits, networks, and systems increased exponentially.

• 1983. AT&T agreed in a court settlement to divest itself of operating companies that provide basic local telephone service to various geographic regions of the US as a result of an anti-trust suit filed by the federal government.

• Mid 1980s to 1995. The United Stated National Science Foundation (NSF) funded a high-speed backbone calles the NSFNET.


History of Datacom• 1989. Tim Berners-Lee and Robert Cailliau build

the prototype system which became the World Wide Web at CERN.

• 1991. Anders Olsson transmits solitary waves through an optical fiber with a data rate of 32 billion bits per second.

• 1992. Neil Papworth sends the first SMS (or text message).

Internet2 organization is created.• 1994. Internet radio broadcasting is born.• 1999. 45% of Australians have a mobile phone.

Sirius satellite radio is introduced.


History of Datacom• 2001. First digital cinema transmission by

satellite in Europe of a feature film by Bernard Pauchon and Philippe Binant is undertaken.

• 2003. Apple launches the iTunes Music Store and sells one million songs in its first week.

MySpace is launched.

• 2004. What would become the largest social networking site in the world, Facebook is launched.

• 2005. YouTube, the video sharing site is launched.

• 2006. Twitter, microblogging is introduced.ECE @Saint Louis University, Baguio City 17

History of Datacom

ECE @Saint Louis University, Baguio City 18Source: http://www.internetsociety.org/internet/what-internet/history-internet/brief-history-internet

• Internet Timeline

Module 2Datacom Network, Architecture,

Protocols, and Standards

Chapter 21

Electronic Communications Sytems , Fifth Editon

By: Wayne Tomasi

ECE @Saint Louis University, Baguio City19


Datacom Network, Architecture, Protocols, and Standards

• Network Architecture. A system that outlines the products and services necessary for the individual components within a data communications network to operate together. It is a set of equipment, transmission media, and procedures that ensures that a specific sequence of events occurs in a network in the proper order to produce the intended results.



• Data Communications Protocol. Sets of rules governing the orderly exchange of data within the network or a portion of the network.

• Protocol Stack. The list of protocols used by a system which normally includes one protocol per layer.



• Network Protocol Clasification.

– Current. Most modern and sophisticated

– Legacy. Old but still useful

– Legendary. Old and no longer in use

• Computer Network General Classification.

– Broadcast. Involves all stations in the network sharing the communications channel.

– Point to point. Involves only two stations at a time.



• Connection-Oriented Protocol.

– Requires a handshake prior to transmission

– Generally requires acknowledgement procedures

– Often provides an error control mechanism

– Connection is dropped by a specific handshake when it is no longer needed

*Handshake. A connection procedure that ensures the integrity of the connection between stations in a network prior to the exchange of data between them.



• Connectionless Protocol.

–Does not require a handshake prior to transmission

–Does not support error control or acknowledgment procedures

– Is more efficient because the data being transmitted do not justify the extra overhead required by connection-oriented protocols



• Standard. An object or procedure considered by an authority or by general consent as a basis of comparison.

• Data Communications Standards. Guidelines that have been generally accepted by the data communications industry. They outline procedures and equipment configurations that help ensure an orderly transfer of information between two or more data communication equipment of networks.



• Classification of Standards.–Proprietary Standards. Closed system

standards generally manufactured or controlled by one company.

–Open System Standards. Guidelines that can be used by any company to produce compatible equipment or software after a royalty has been paid to the original company.


Standards Organizations for Data Communications

• ISO. International Standards Organization

• ITU-T. International Telecommunications Union-Telecommunications Sector

• CCITT. Comité Consultatif Internationale de Télégraphieet Téléphonie

• IEEE. Institute of Electrical and Electronics Engineers

• ANSI. American National Standards Institute

• EIA. Electronics Industry Association

• TIA. Telecommunications Industry Association




ISO

ITU-T IEEE ANSI

EIA TIA


• ITU-T Study Groups:– Network and Service Operation

– Tariff and Accounting Principles

– Telecommunications Management Network and Network Interface

– Protection Against Electromagnetic Environment Effects

– Outside Plant

– Data Networks and Open Systems Communications

– Characteristics of Telematic Systems

– Television and Sound Transmission

– Language and General Software Aspects of Telecommunication Systems

– Signaling Requirements and Protocols

– End-to-end Transmission Performance of Networks and Terminals

– General Network Aspects

– Transport Networks, Systems, and Equipment

– Multimedia Services and Systems



• IAB. Internet Architecture Board

– Oversees Internet architecture protocols and procedures.

– Manages processes used to create Internet standards and serves as an appeal board for complaints on the proper of execution of such processes.

– Administers various Internet assigned numbers.

– Represents Internet Society interests in liaison relationships with other organizations.

– Source of advice for guidance to the Internet Society concerning technical, architectural, procedural, and policy matters concerning the Internet and its enabling technologies.

• IETF. Internet Engineering Task Force

• IRTF. Internet Research Task ForceECE @Saint Louis University, Baguio City 30



IAB

IETF IRTF

Layered Network Architecture

• The layering of network responsibilities allows each layer to add value to services provided by sets of lower layers.

• Layered architecture facililitates peer-to-peer network protocols.

• Layered architecture allows different computers to communicate at different levels.

• When technological advances occur, it is easier to modify one layer’s protocol without having to modify all the other layers.

• The disadvantage of layered architecture is the tremendous amount of overhead required.


Layered Network Architecture

• Protocol Data Unit (PDU). A unit of data used to facilitate seamless exchange of information between layers of the protocol stack. Consists of a header and/or trailer appended to the data as it passes through a layer.

• Encapsulation. The process of adding a protocol data unit as the data frame passes from an upper layer to the layer immediately below it. (Downward direction)

• Decapsulation. The process of removing a protocol data unit as the data frame passes from a lower to the layer immediately above it. (Upward direction)


Popular Layered Protocols

• OSI (Open Systems Interconnection). A seven layer protocol developed and adopted by the ISO and the ITU-T in 1983.

• TCP-IP (Transmission Control Protocol/Internet Protocol).A three or four layer protocol developed by the Department of Defense of the United States before the inception of the OSI model.

• CISCO THREE-LAYER MODEL. A Three-layer logical hierarchy developed by CISCO that specifies where things belong, how they fit together, and what functions go where.


Open Systems Interconnection

User networking applications and interfacing to the network

Encoding language used in transmission

Job management tracking

Data tracking as it moves through a network

Network addressing and packet transmission on the network

Frame formatting for transmitting data across a physical communications link

Transmission method used to propagate bits through a network


LAYERS FUNCTIONS



TCP/IP



OSI and its Protocol Data Units


TCP-IP Protocol Layers

• Network Access Layer. Provides a means of physically delivering data packets using frames or cells.

• Host-to-host Layer. Services the process and Internet layers to handle the reliability and session aspects of data transmission.

• Internet Layer. Contains information that pertains to how data can be routed through the network.

• Process Layer. Provides applications support.


CISCO Protocol Layers

• Core Layer. Top layer responsible for transporting large amounts of data traffic reliably and quickly. Primarily tasked to switch traffic as quickly as possible.

• Distribution Layer/Workgroup Layer. The communication point between the access and the core layers that provides routing, filtering, WAN access, and control on the number of data packets allowed to access the core layer.

• Access Layer/Desktop Layer. Responsible for access control, segmentation (creation of collision domains), and workgroup connectivity to the distribution layer.
