2008 SpringC.-S. Shieh, EC, KUAS, Taiwan1 Chapter 0 Computers and the Internet Chin-Shiuh Shieh ( 謝欽旭 ) Department of Electronic Engineering National Kaohsiung University of Applied Sciences, Taiwan

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan2 Outline What are computers? Why computer networks? What are computer networks? The Internet Evolution of connections Applications

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan3 What Are Computers? Computers are powerful tools for (generalized) computation –Numerical analysis, database, document processing, control, gaming, … Computers are fast, precise, and highly flexible. Complementary roles between man and machine –Human being: Thinking, innovating, … –Machine: Data processing, computation, …

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan4 Why Computer Networks? A single computer, however powerful, is an isolated island. A computer can increase its power by communicating with others: –More information, more computing power, more reliable service, … Computer networks allow for information exchange at the speed of light.

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan5 What Are Computer Networks? Computer networks consist of –Physical connections: Cable, optical fiber, radio channel, … –Communication protocols: Defining the format, timing of signals/packets at different layers. Different protocols make different network systems. –Applications: Client/server programs for different services.

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan6 What Are Computer Networks? (cont) Directions of the evolvement of computer networks –Local Area Network (LAN) for file/printer sharing, such as Microsoft Network Neighborhood. –Wide Area Network (WAN) for global communications, such as the Internet. –The boundary is getting blurred.

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan7 The Internet –A global network with the interconnection of hosts/networks running TCP/IP. –TCP/IP is a free/open standard. Any manufactures can incorporate it into their products. –Cross-platform with global coverage.

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan8 The Internet (cont)

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan9 The Internet (cont)

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan10 The Internet (cont)

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan11 The Internet (cont) Typical applications – , remote login, file transfer, world-wide- web, remote control, instant message, voice over IP, video conference, blog, … –Possible applications are limited only by one’s imagination. –All node on Internet are born to be equal. To be a client or a server depends on your decision.

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan12 The Internet (cont) Service paradigms –Client-server architecture –Peer-to-peer architecture –Hybrid architecture

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan13 The Internet (cont) Internet 1. Server machine is powered on and connected to Internet all the time. 2. HTTP server (web server), such as apache, is running on server machine. 3. Web pages to be served are placed on server. 4. Client machine is powered on and connected to Internet when necessary. 5. HTTP client (browser), such as Internet Explorer, is invoked. 6. Request for a particular web page. 7. Response with requested web page. 8. HTTP client parses and displays web pages on screen. Client-server architecture

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan14 Evolution of Connections Core –Frame-relay –ATM –… Edge (last mile) –Modem –ADSL –Cable-TV –Ethernet – –3G/UMTS –WiMAX –… Cited from James F. Kurose and Keith W. Ross, Computer Networking: A Top-Down Approach Featuring the Internet, 2nd Ed., Addison Wesley

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan15 Evolution of Connections (cont) Modem –Using voice band (<4K Hz) –V.92 at 56Kbps –Free for now PSTN Internet Public Switching Telephone Network Internet Service Provider modem

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan16 Evolution of Connections (cont) ADSL (Asymmetric Digital Subscriber Line ) –Using band beyond voice (>4K Hz) –ADSL modem, Ethernet card –1M/64K, 2M/256K, 8M/640K, … –2M/256K at NT$840 per month (Hinet)

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan17 Evolution of Connections (cont) Cited from

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan18 Evolution of Connections (cont) Digital Subscriber Line Access Multiplexer (DSLAM) Broadband Remote Access Server (BBRAS) Radius Server: An authentication and accounting server for terminal servers that speak the RADIUS protocol

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan19 Evolution of Connections (cont) Cable-TV –Using channels not for casting –Cable modem –1.5M/64K, 3M/256K, 6M/256K, … –3M/256K at NT$850 per month (Giga.net)

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan20 Evolution of Connections (cont) Cited from

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan21 Evolution of Connections (cont) Ethernet –Ethernet card, hub, switching hub –10Mbps, 100Mbps, 1000Mbps –Carrier Sense Multiple Access with Collision Detection (CSMA/CD)

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan22 Evolution of Connections (cont) Internet hub switching hub router Ethernet LAN

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan23 Evolution of Connections (cont IEEE –Wireless LAN, Wi-Fi – wireless network card, access point –11Mbps (802.11b), 55Mbps (802.11g) –Tens of meters or next two doors –Wireless extension to Ethernet

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan24 Evolution of Connections (cont) Internet hub switching hub router access point

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan25 Applications (cont) Internet Gateway GSM/GPRS Gateway UMTS Networking via Mobile Phone Systems

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan26 Evolution of Connections (cont) Networking via Mobile Phone Systems –1G: Advanced Mobile Phone System –2G: GSM (Global System for Mobile Communication) Circuit-switched 14.4 Kbps –2.5G: GPRS (General packet Radio Service) Packet-switched 160Kbps (30-80 Kbps in practice)

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan27 Evolution of Connections (cont) –3G: UMTS (Universal Mobile Telecommunication System) 1920 Kbps (384 Kbps in practice) 中華電信 3G mPro 商務 450 型, 450 元 / 月, ( 贈送國 內數據 50 萬封包，約 61MB), 每一封包為 128 Bytes 台灣大哥大 catch 3G 399 型, 399 元 / 月, ( 贈送 40MB), 元 /KB –3.5G: HSDPA (High Speed downlink Packet Access) 14.4 Mbps

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan28 Evolution of Connections (cont) WiMAX –Worldwide Interoperability for Microwave Access, 中 文譯名為「無線都會區域網路」 –IEEE (WiMAX), IEEE e (Mobile WiMAX) –Up to 75Mbps, 50Km, Wireless MAN (Metropolitan Area Network) –Last mile alternative to cable and DSL –Scheduling MAC (Media Access Control), OFDM (Orthogonal Frequency Division Modulation) – 行政院經濟部「台灣 WiMAX 發展藍圖」, 「 WiMAX 加 速計畫」 –Fee: ?

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan29 Evolution of Connections (cont) Cited from 工研院 IEK 2005/08

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan30 Evolution of Connections (cont) Cited from 工研院 IEK 2005/08

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan31 Applications Classical applications – , file transfer, remote login, bullet board system, gopher, archie, netnews, IRC (Internet Relay Chat, exchange text messages interactively with other people all over the world), … –Attachments in s allow for the transfer of files of any types. –Web-based client is convenient when you are out.

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan32 Applications (cont) The raise of world-wide-web –Hyper-Text Markup Language –Presentation with multimedia, including text, graph, audio, video, animation, … –Hyperlinks for cross-reference –Integration of other services, such as , file downloading, telnet, … –Excellent platform for promotion for both enterprises and individuals.

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan33 Applications (cont) Interactive technologies bring WWW into new dimensions –E-commerce, database access, web search, remote control, … –Programming is involved JavaScript / VBScript at client end Active Server Page (ASP, Microsoft) / PHP: Hypertext Preprocessor at server end Common Gateway Interface Programming (CGI)

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan34 Applications (cont) Web 2.0 –Not a brand new technology, but a new concept –blogs and wikis –A wiki is a type of website that allows users to easily add, remove, or otherwise edit and change some available content, sometimes without the need for registration "Wiki-wiki" means "hurry quick" in Hawaiian. It also refers to a type of native fish of the islands (from wikiapedia).

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan35 Applications (cont) –Users turn their roles from audiences to authors – 人人皆可著書立說

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan36 Applications (cont) Recent applications –Instant message –Voice over IP –Multimedia streaming –Remote login, Wake-On-LAN –P2P –…

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan37 Applications (cont) Instant message –Microsoft MSN Messenger, Yahoo Messenger, ICQ, … –Presence service –Text chatting, voice conference, video conference, file transfer, …

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan38 Applications (cont) Internet Presence Server Alice Bob 1. Alice login2. Bob login 3. Bob is online 3. Alice is online 4. Text chatting, voice conference, video conference, file transfer, …

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan39 Applications (cont) Voice over IP –Skype, Microsoft MSN Messenger, Google Talk, … –Presence service, gateway to PSTN, GSM –Free for PC-to-PC –Charged for PC-to-Phone (Skype Out) € per minute to USA, UK, Taiwan, China, … € per minute to Taiwan mobile Hant/products/skypeout/rates/all_rates.html

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan40 Applications (cont) Internet Presence Server Alice Bob PSTN Gateway GSM/3G Gateway Cindy David Skype Out

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan41 Applications (cont) Multimedia casting –Network radio, network TV, Web-TV… –EZTV v by 全球網通科技

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan42 Applications (cont) –Live casting –SimpleCam v1.3 by Dead Pirate Software –For surveillance or just show off

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan43 Applications (cont) Remote login –Telent is a text-based remote login. –SSH is a secure replacement of telnet. –Remote login with graphic user interface (GUI) Remote Desktop for Microsoft Windows Virtual Network Computing (VNC) for cross- platform –As if you are in front of the target machine.

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan44 Applications (cont) Internet Remote login

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan45 Applications (cont) Virtual Private Network (VPN) –As if you and your machine are in the target domain –For access of restricted data in the target domain Internet connect to VPN hub VPN server

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan46 Applications (cont) Peer-to-Peer (P2P) applications –Each node acts both as a client and a server –Distribution of large files –eMule, BitTorrent, … –Warning: illegal use of legal applications

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan47 Applications (cont)

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan48 Applications (cont)

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan49 Applications (cont)

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan50 Applications (cont)

2008 SpringC.-S. Shieh, EC, KUAS, Taiwan51 Applications (cont)