How the Internet Works

1. How the Internet Works Lunch and Learn Session April 12, 2001 Bill VilbergInstructional Advancement Center

2. Agenda • Sorting the mail • Driving the highways • Tweaks and Utilities • Appendix Ed-Tech Lunch and Learn Series

3. Sorting the Mail The US Postal Service analogy

4. Note to your neighborPostal Service • Address envelope • Deliver to neighbor Ed-Tech Lunch and Learn Series

5. Note to Your Neighbor Computer Network • Address is an IP number • 129.171.43.9 • Neighbors have the same first digits • 129.171.43.x • Send message directly from your computer to your neighbor Ed-Tech Lunch and Learn Series

6. Note to Your Neighbor Network Diagram (129.171.43.9) 129.171.43.5 Ed-Tech Lunch and Learn Series

7. In-Town LettersPostal Service • Address envelope • Give to carrier • Sort at post office • Pass to carrier • Deliver to addressee Ed-Tech Lunch and Learn Series

8. In-Town LettersComputer Network • Address message • Send to “gateway” • Gateway passes information beyond neighborhood and between networks • Deliver to addressee Ed-Tech Lunch and Learn Series

9. In-Town LettersNetwork Diagram 129.171.43.254 129.171.16.254 (129.171.43.9) 129.171.32.254 129.171.32.2 Ed-Tech Lunch and Learn Series

10. Out of town lettersPostal Service • Address message • Give to carrier • Sort at post office • Sort at regional center • Sort at receiving post office • Pass to carrier • Deliver to addressee Ed-Tech Lunch and Learn Series

11. Out of town lettersComputer Network • Address envelope • Send to gateway • Pass on to gateway • Pass on to gateway • Pass on to gateway • Pass on to gateway… • Deliver to addressee Ed-Tech Lunch and Learn Series

12. Out of Town LettersNetwork Diagram .43.254 .43.9 .16.254 .16.253 .32.254 129.171.32.2 Ed-Tech Lunch and Learn Series

13. Delivery RuleComputer Network • If the address is local, deliver it. • If the address is not local, send it to the gateway. • Define “local” from subnet mask. • 255.255.255.0 matches first three numbers • 255.255.0.0 matches the first two numbers Ed-Tech Lunch and Learn Series

14. The Three Numbers • IP Number (Who am I?) • 129.171.43.9 • Mask (Who are my neighbors?) • 255.255.255.0 • Gateway (Who passes on my messages?) • 129.171.43.254 Ed-Tech Lunch and Learn Series

15. Finding Your Three Numbers • Windows 95/98 • Start, Run, “winipcfg” to see • Start, Settings, Control Panel, Network, TCP, Properties to set • Windows NT • Command Prompt, “ipconfig” (?) to see • DEMO Ed-Tech Lunch and Learn Series

16. Delivery Delays Why isn’t it faster?

17. Highway Analogy • Highway: Cars and trucks drive on roads and streets • Network: Information packets are sent over wires Ed-Tech Lunch and Learn Series

18. Factor 1: Speed of Electricity • Highway: Speed limit (absolute) • Network: Speed of light? Ed-Tech Lunch and Learn Series

19. Factor 2: Speeds of Devices • Highway analogy: Speed that you drive, type of vehicle, toll plazas, rest stops, refueling stops • Network: Get faster equipment, network connections Ed-Tech Lunch and Learn Series

20. Factor 3: Congestion, Collisions, Bottlenecks, Equipment Failures • Highway analogy: What happens if an Interstate highway exits onto a dirt road? • Network: What happens in the red area of this network? Ed-Tech Lunch and Learn Series

21. Speeding Delivery • Faster computer • Faster CPU • More memory • Faster interface card/network connection • 56Kb hardware-based modem • Cable or DSL connection • 100 Mb Switched-Ethernet connection • Tweaks • (next section) Ed-Tech Lunch and Learn Series

22. Tweaks and Utilities

23. Speed Tests • www.dslreports.com, Tools, Speed Tests • http://speedtest.mybc.com/ • http://www.toast.net/performance/ • http://www.fastaccesscentral.com/ (?) Ed-Tech Lunch and Learn Series

24. Tweaks (Use Care) • http://tweakhomepc.virtualave.net/thpc.html • http://www.dslreports.com/tweak • http://www.speedcorp.net/downloads.shtml • http://coverage.cnet.com/Content/Features/Howto/Netspeed/ss09.html Ed-Tech Lunch and Learn Series

25. Appendix

26. DNS Server • A Domain Name Server (DNS) converts names to numbers. • All Internet addresses are numbers. • Every name (www.miami.edu, www.microsoft.com, www.vilberg.com, www.courses.miami.edu, http://inst05.merrick.miami.edu) has a unique number associated with it. • UM Primary DNS = 129.171.32.1 Ed-Tech Lunch and Learn Series

27. Proxy Server • A proxy server takes your message to someone else, and sends it on as a new message from itself. When a reply comes back, the proxy server sends the reply to you. To the other service it looks like everything is coming from the proxy server, not from you. This solves authentication/authorization problems. • See www.library.miami.edu, Databases, Remote Access Information for UM details. Ed-Tech Lunch and Learn Series

28. DHCP Server • A DHCP server sets all of your numbers for you each time you use the Internet. It allows me to take my portable anywhere on campus and get the right numbers for that location. • The unique hardware address of your interface identifies you to the DHCP server. You can find this number at (Win 95/98) Start, Run, winipcfg Ed-Tech Lunch and Learn Series

29. 802.11 Wireless • A transmitter/receiver in your computer communicates through a series of transmitters/receivers distributed around the area. Ed-Tech Lunch and Learn Series

30. Demonstration

31. NetHelper • http://www.zdnet.com/downloads/stories/info/0,,000SST,.html Ed-Tech Lunch and Learn Series