1. IT – som værktøj Bent Thomsen Institut for Datalogi Aalborg Universitet

2. September 2003Bent Thomsen - FIT 1-12 Opgaver og øvelser fra sidst Web search Instant messaging Unix – X-win32 version 5.2.2 LaTeX – brug Unix maskinen dolomit

3. Introduction to Networks and the Internet Bent Thomsen Institut for Datalogi Aalborg Universitet

4. September 2003Bent Thomsen - FIT 1-14 What is a network Carrier of data between connected computers What does a network consist of? –End hosts connected to the network –Physical links that carry data Ethernet, FDDI, ATM, … –Routers/switches –Protocols TCP/IP, HTTP, FTP, SMTP, … –Applications that communicate with each other Printing, email, file transfer, web browsers,..

5. September 2003Bent Thomsen - FIT 1-15 Small Local Networks

6. September 2003Bent Thomsen - FIT 1-16 Local Area Networks

7. September 2003Bent Thomsen - FIT 1-17 Large Local Area Networks

8. September 2003Bent Thomsen - FIT 1-18 Client/Server networking Access large data sets and huge computing resources from desktop machines Separate data processing from presentation Facilitate several views on raw data Split workload between machines across a network –Do some processing locally and some on a server –Middleware and distributed objects

9. September 2003Bent Thomsen - FIT 1-19 Direct connection

10. September 2003Bent Thomsen - FIT 1-110 Client/Server connection

11. September 2003Bent Thomsen - FIT 1-111 Web based client/server

12. September 2003Bent Thomsen - FIT 1-112 The Internet A set of connected networks –All use the same network protocol (IP) Most common protocol used is TCP/IP –Connection oriented –Reliable, in-order byte-stream Application protocols on top of TCP/IP –SMTP –HTTP –FTP UDP is another protocol –Used for streaming video and audio –Some peer-to-peer applications Protocols define format, order of messages and actions taken on messages

13. September 2003Bent Thomsen - FIT 1-113 The Internet is a collection of interconnected networks

14. September 2003Bent Thomsen - FIT 1-114 Connecting to the Internet Through ISP –Modem dialup –Always-on: ADSL, Cable, FWA Direct/Dedicated network –Companies –Universities –(WLAN operators)

15. September 2003Bent Thomsen - FIT 1-115 How to connect to the Internet

16. September 2003Bent Thomsen - FIT 1-116 An Internet Backbone

17. September 2003Bent Thomsen - FIT 1-117 A bigger Internet backbone UUNet/WorldCom

18. September 2003Bent Thomsen - FIT 1-118 Some Internet basics Each computer on the internet has a unique address – the IP address –123.225.409.109 –Most end-user computers are allocated an IP address when they connect – DHCP –IP addresses can be given a name E.g www.but.auc.dkwww.but.auc.dk Looked up via DNS (130.225.56.21)

19. September 2003Bent Thomsen - FIT 1-119 Package switched

20. September 2003Bent Thomsen - FIT 1-120 Routing on the Internet

21. September 2003Bent Thomsen - FIT 1-121 Things that may be in your way Operating system settings Gateways Firewalls Proxy servers Caches Virus filters Spam filters Adult filters

22. September 2003Bent Thomsen - FIT 1-122 Internet Applications Electronic mail (email) Mailing lists Newsgroups File Transfer Chat Instant Messaging World Wide Web

23. September 2003Bent Thomsen - FIT 1-123 The World Wide Web 1991 The web (HTML/HTTP) - 1 web server 1993 The Mosaic Browser - 186 web servers 1994 Netscape – over 42000 web servers 1995 Internet Explorer - over 200000 web servers 1995 Java 1996 Browser wars – over 1 million web servers 1997 IE4 1998 XML and WAP – over 5 million web servers 1999 IE5

24. September 2003Bent Thomsen - FIT 1-124 “a consensual hallucination experienced daily by billions of operators in every nation …” Gibson Cyberspace