四川大学：《计算机网络 Computer Networks》课程教学资源（PPT课件讲稿）Unit5 Introduction to Computer Networks

UNIT 5. Introduction to Computer Networks Feng Lin Sichuan Univ

Feng Lin Sichuan Univ

Outline Unit 5.1 Basic of Internet Unit 5.2 More on Computer Networks Unit 5.3 Network Architecture

 Unit 5.1 Basic of Internet  Unit 5.2 More on Computer Networks  Unit 5.3 Network Architecture

Unit 5.1 Basic of internet

Agenda First sight of communication Everything is Connected to Everything Applications of Internet Web Email Classification of Computer Networks Transmission media S LAN MAN WAN Client/Sever vs peer to Peer

 First Sight of Communication  Everything is Connected to Everything  Applications of Internet  Web  Email  Classification of Computer Networks  Transmission Media  LAN,MAN,WAN  Client/Sever vs Peer to Peer

First sight of communication The human need to communicate has motivated mankinds creativit Cave dwellers drew pictures on walls Smoke signals, drum rhythms passed messages Postal service: a system for physically transporting documents and other small packages Alexander Graham Bell: invented the telephone Data communication Data communications are the exchange of data between two devices via some form of transmission medium

• The human need to communicate has motivated mankind’s creativity: – Cave dwellers drew pictures on walls. – Smoke signals, drum rhythms passed messages. – Postal service: a system for physically transporting documents and other small packages – Alexander Graham Bell: invented the telephone.  Data Communication: Data communications are the exchange of data between two devices via some form of transmission medium

What is needed for successful communications? ending Communications Communications device - initiates device-connects channel- media instruction to the sending device to on which data transmit data the communications instructions, or instructions, or channel information travel information Communications Receiving device -connects device -accepts the communications transmission of data channel to the instructions or receiving device information

7 Sending device — initiates instruction to transmit data, instructions, or information What is needed for successful communications? Communications device — connects the communications channel to the receiving device Receiving device — accepts transmission of data, instructions, or information Communications device — connects the sending device to the communications channel Communications channel — media on which data, instructions, or information travel

Everything is Connected to Everything Computer Network: A collection of computers, display terminals, printers, and other devices linked either by physical or wireless means Seeds of Networking 1966: ARPA(Advanced research Projects Agency) State Defense Departments research organization Focused major development effort on computer networking ARPAS Goal: To promote research in advanced future technologies by funding university and industry research proposals Result: Thousands of databases became available to the public

 Computer Network: A collection of computers, display terminals, printers, and other devices linked either by physical or wireless means.  Seeds of Networking ◦ 1966: ARPA (Advanced Research Projects Agency) State Defense Department’s research organization.  Focused major development effort on computer networking.  ARPA’s Goal: To promote research in advanced future technologies by funding university and industry research proposals.  Result: Thousands of databases became available to the public

Everything is Connected to Everything Computer Networking Internet: A world-wide network connecting millions of computer networks for the purpose of exchanging data and communications using special rules of communication internet: (lower case 1) Any network connecting two or more computer networks Going online: Connecting to a collection of interconnected computers on a network Do bankin Pay bills Buy groceries Book vacation travel Send messages Participate in discussions · Do research · Play games

Computer Networking • Internet: A world-wide network connecting millions of computer networks for the purpose of exchanging data and communications using special rules of communication. • internet: (lower case i) Any network connecting two or more computer networks. Going online: Connecting to a collection of interconnected computers on a network. • Do banking. • Pay bills. • Buy groceries. • Book vacation travel. • Send messages. • Participate in discussions. • Do research. • Play games

Everything is Connected to Everything Instant Web E-Mail Messaging Internet Chat rooms Newsgroups Telephony Fax machine Web Video FTP or Computer Folders Conferencing Fax modem

10 Web E-Mail Instant Messaging Internet Telephony Chat Rooms Newsgroups Web Folders Fax Machine or Computer Fax/Modem Video Conferencing FTP

Internet basics The Internet backbone Major internet communication links Network/Internet service provider(NsP/IsP Construct and maintain the Internet back bone such as at&t Network access point(NAP)-point on the Internet where several connections converge Han Fala United States

 The Internet Backbone  Major internet communication links.  Network/Internet service provider (NSP/ISP) ◦ Construct and maintain the Internet backbone, such as AT&T  Network access point (NAP) – point on the Internet where several connections converge