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3.2 The internet

3.2 The internet. A worldwide system of computer networks A network which users can (with permission) get information from any other computer

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3.2 The internet

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  1. 3.2 The internet • A worldwide system of computer networks • A network which users can (with permission) get information from any other computer • The original aim of creating internet was to create a network that would allow users of a research computer at one university to be able to "talk to" research computers at other universities • Today the Internet is a public, cooperative, and self-sustaining facility accessible to hundreds of millions of people worldwide

  2. 3.2.1 Historical Background of the Development of the Internet • The birth of the Internet • Was created for military purposes by ARPANET (Advanced Research Projects Agency Network) in 1969 • Transmission speed was slow (56kbps) • System was made up of research institutes and universities inside the US connected by a packet network

  3. 3.2.1 Historical Background of the Development of the Internet • Development of the basic technology • TCP/IP is the fundamental technologies and the standard protocol on the Internet • Development of networks(1980) • 1983 – no more military network,remain science and research • 1986 – started as independent network

  4. 3.2.1 Historical Background of the Development of the Internet • The rapid grow of the Internet(1990s) • The birth of commercial networks • NII (National Information Infrastructure) plan • Increasingly powerful computers

  5. 3.2.2 The Structure of the Internet • A network of networks • Many small LANs and WANs joined together to become a big network • Different between the Internet and Personal computer communication • Personal computer communication networks are runs by companies that have a host computer and offer various services such as database • Internet has no mother organization, anyone can receive services

  6. 3.2.2 The Structure of the Internet • The Internet and TCP/IP • Have to employ this communication protocol to access to internet • Not managed by any international organization • De facto standard protocol

  7. ISP (Internet Service Provider) Internet AAA CCC Skyinet Pacific Infocom Access Point Access Point ISDN

  8. Leased Line Connection Internet ISP High speed digital line （64Kbps～6Mbps） Network in office Network in office

  9. ISDN Land Line Dial-up Connection Internet ISP ●Land Line（～56Kbps） ●ISDN （64Kbps、128Kbps） Network in office Home, Hotel etc Network type Dial-up Connection Terminal type Dial-up Connection

  10. 3.2.3 Internet Technology • IP routing • Each computer connected to the network is given an IP address(unique address) • IP routing is a technique that determines the transmission route from the sender to the destination

  11. 3.2.3 Internet Technology • DNS (Domain Name System) • Readable name instead of IP (all numbers) • One-to-one coordination between a domain name and the IP address • Tell you “which country”“what kind of organization”“who” from the address

  12. Domain Root Domain net com jp uk xxx fujitsu yyy jp aaa pr svr1 Expression of Host name svr1.aaa.fujitsu.com. Host name. Domain name FQDN aaa.fujitsu.comdomain

  13. E-mail Internet Domain aaa Domain bbb Mail Server Mail Server 3 5 4 2 6 1. Creation of an e-mail 2. Sending the e-mail 3. Analysis of the destination 4. Sending the e-mail to Domain bbb by mail server 5. Acceptance of the e-mail and keep in the mail server 6. Get the e-mail 1

  14. 5.5.1　電子メールアドレス e-mail address User Identification Consist of user name and domain name Notation ： user name@domain Name e.g. ： hiro@fujitsu.com.ph Domain name User name Separation

  15. WWW WWWServer WWWServer HTML data Media data HTMLdata Media data Data send Data send Requirement （URL） Requirement （URL） WWWClient Browser

  16. 5.6.1　URL URL; Syntax for access to the information on the Internet Notation Protocol://Server name/Directory path/File name e.g. http://www.fujitsu.com.ph/about/index.html

  17. WWW client Mechanism for Delivery of HTML Documents Document root htdocs http://www.flm.co.jp/ directory flm Image file image.gif HTML file (default document) index.html http://www.flm.co.jp/flm/flm.html http://www.flm.co.jp/flm/ HTML file (default document) index.html HTML file flm.html www.flm.co.jp WWW server

  18. Processing programs database HTML contents CGI scripts Request for HTML file/image file by URL Send HTML file/image file WWW service browser Call CGI scripts by URL WWW client Send processed HTML document WWW server WWW Server Features

  19. When DNS is not used mars IN A 202.248.79.66 www IN A 202.248.79.68 To 202.248.79.66 flm.co.jp domain Host name : mars connection IP address: 202.248.79.66 To mars.flm.co.jp When DNS is used connection What is DNS

  20. FTP User Result Require User Interface Port #21 Command Control process Reply I/O File Transfer process Port #20 File Data transfer I/O FTPServer FTPClient

  21. 3.2.6 Search Engine • An information retrieval tool • Search Engine • Directory type : www.yahoo.com • Robot type– program that automatically search WWW : www.google.com • Search Methods • Keyword search– Based on keyword • Directory search– Narrow search object to fields

  22. 3.2.7 Internet Related Knowledge Quality of Service– indicate the quality of service xDSL (x Digital Subscriber Line)– High speed transmission Best Effort Service– Low charges and no guarantee of service CGI (Common Gateway Interface)– Interface between WWW server and programs VoIP (Voice over IP)– Voice data transmission technology employing the IP protocol

  23. xDSL • DSL（Digital Subscriber Line）technology is used. • Broad band service to use telephone line (metallic cable) Unused frequency Digital data Telephone Telephone cable Home ISP

  24. xDSL service • ｘDSLservice • Uses DSL(Digital Subscriber Line) Technology. • Analog line 100M 30M 20M 10M 5M 2M 1M 500k 200k 100k VDSL Asymmetric Symmetric ADSL HDSL 300ｍ 1Km 2Km 3Km 4Km 5Km 6Km

  25. ADSL; • Different frequency is used on up-stream and down-stream Home ISP Telephone cable phone Splitter Splitter Internet ADSL MODEM

  26. PBX VoIP service LAN WAN Voice VoIPRouter VoIPRouter PBX

  27. Access allowed Barrier segment Internet Public server Access allowed • DNS • WWW • Mail router Access denied Firewall Local segment What is a Firewall

  28. <Firewall> Upper level Application level Internet Internal network Lower level TCP/IP level Firewall Technologies(Packet Filtering)

  29. Overview of Proxy Server Barrier segment Internet Public server router x Proxy Local segment Internal server

  30. (2) Accept requests Proxy server (3) (1) (5) (4) x External server ( WWW server) blocked Internal client ( browser) Firewall Proxy Server Features

  31. External server ( Internet ) Proxy server Internet Access control via IP address Filtering by protocol Internal network x x http protocol ftp protocol IP address : 172.20.1.3 IP address : 172.20.1.4 Access Control and Filtering

  32. (6) Request for Fujitsu homepage (4) data caching Fujitsu homepage F L M homepage • • • (7) Retrieving cache data (3) Internal client (5) Fujitsu WWW server (external server) (2) Proxy server Request for Fujitsu homepage (1) Internal client Cache Feature

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