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Lecture # 35 Internet Organization

Lecture # 35 Internet Organization. Internet. Networking. Communicating between two or more computers Bits -> voltage ->wire->voltage->Bits. Network. More than two computers. Network switch. More than two computers. Switch. Network. Who is talking to who?. Switch. Network. 1.

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Lecture # 35 Internet Organization

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  1. Lecture # 35 Internet Organization

  2. Internet

  3. Networking • Communicating between two or more computers • Bits -> voltage ->wire->voltage->Bits

  4. Network • More than two computers

  5. Network switch • More than two computers Switch

  6. Network • Who is talking to who? Switch

  7. Network 1 • Who is talking to who? • Give each computer an address (integer) 0 2 Switch 75 43 42

  8. Network 1 • Who is talking to who? • Give each computer an address (integer) • Add the address to the message • Computer with that address takes the message • All others ignore the message 0 2 Switch 75 message address 43 42

  9. Internet net net net net message address

  10. Internet net net net net net ID host ID message address

  11. Internet and WWW

  12. Internet • A way to send an array of bytes from any machine to any other machine Internet

  13. How to identify the machine to send to • By address (IP Address - 4 bytes) 233.21.1.45 128.78.22.32 Internet 117.211.23.22 233.12.32.111

  14. How to identify the machine to send to • By name (domain name) Icie.cs.byu.edu Croatian.cs.byu.edu Internet Yahoo.com Myhome.isp.com

  15. Domain Name - a pathname in a tree GOV COM EDU LOC BYU MIT Utah Microsoft Yahoo whitehouse EE research CS WWW ICIE

  16. Icie.cs.byu.edu GOV COM EDU LOC BYU MIT Utah Microsoft Yahoo whitehouse EE research CS WWW ICIE

  17. Servers • Computers that store information or services Icie.cs.byu.edu Internet Yahoo.com

  18. Clients • Programs that help users get access to info Netscape Internet Instant messenger

  19. Protocol • Language for computers to talk with each other Netscape HTTP Internet IRC Instant messenger

  20. Review • Internet • Array of bytes between computers • By address 128.23.12.1 • By name icie.cs.byu.edu • Server - delivers info on request • Client - helps user access server info • Protocol - language for computers to talk with each other

  21. URL (Uniform Resource Locator) • http://www.yahoo.com/ • http://www.espn.com/nba • http://icie.cs.byu.edu/cs100/schedule.html

  22. URL - Protocol • http://icie.cs.byu.edu/cs100/schedule.html • ftp://netscape.com/downloads/msng.exe • mailto:george.w.bush@whitehouse.gov

  23. URL - Domain Namename of the server to access • http://icie.cs.byu.edu/cs100/schedule.html • ftp://netscape.com/downloads/msng.exe

  24. URL - page name • http://icie.cs.byu.edu/cs100/schedule.html • ftp://netscape.com/downloads/msng.exe

  25. URL - page name • http://icie.cs.byu.edu/cs100/schedule.html • http://icie.cs.byu.edu/cs100/Lectures/server.gif • http://icie.cs.byu.edu/cs100/Lectures/L1.ppt • http://icie.cs.byu.edu/cs456/Homework/Program1 • http://icie.cs.byu.edu/cs456/Homework/Program2 • -

  26. URL - page name • http://icie.cs.byu.edu/cs100/schedule.html • http://icie.cs.byu.edu/cs100/Lectures/server.gif • http://icie.cs.byu.edu/cs100/Lectures/L1.ppt • http://icie.cs.byu.edu/cs456/Homework/Program1 • http://icie.cs.byu.edu/cs456/Homework/Program2 • Page names are pathnames in a tree

  27. URL - page name • cs100/schedule.html • cs100/Lectures/ server.gif • cs100/Lectures/L1.ppt • cs456/Homework/Program1 • cs456/Homework/Program2 cs456 cs100 Homework Lectures Program1 schedule.html Program2 server.gif L1.ppt

  28. Hypertext • How to link together many documents so that users can get whatever information they want.

  29. IP address 128.187.172.236 a computer BYU Computer Science net ID host ID message address

  30. Internet Protocol (IP) • Computer sends an IP “packet” • Other computers (routers) send it on until it reaches the destination computer • (IP address) • Each packet might get lost, may arrive in any order, may get delayed message IP Address 32 bits - 4 bytes

  31. TCP/IP • Uses IP to send packets • Keeps track of which packets have been sent • Resends packets that get lost • Keeps track of the correct order of packets • Reorders packets when they come in the wrong order

  32. Domain names vs. IP address • students.cs.byu.edu • www.byu.edu • ee.utah.edu • yahoo.com • software.microsoft.com • research.microsoft.com

  33. Domain names • students.cs.byu.edu • www.byu.edu • ee.utah.edu • yahoo.com • software.microsoft.com • research.microsoft.com com edu yahoo byu utah microsoft ee cs www students research software

  34. Domain names • If you have a domain name, how do you find the IP address of that computer? • Maybe one computer has a list of all domain names and their IP addresses • If there are millions of computers • Who enters the data? • Who fixes the data? • Millions of requests will swamp that computer • If that computer goes down nothing works • How do we get this to scale?

  35. Domain names - scale • Use a tree! • Every node knows IP address of its parent • Every node knows the IP/domain name of its direct children com edu yahoo byu utah microsoft ee cs www students research software

  36. DNS - domain name service • If a node doesn’t know the IP address of some domain name: • If the domain name is one of its own, ask the correct child • If the name is not one of its own, ask the parent com edu yahoo byu utah microsoft ee cs www students research software

  37. DNS - domain name service • If the domain name is one of its own, ask the correct child • If the name is not one of its own, ask the parent com edu yahoo byu utah microsoft ee cs www students research software students.cs.byu.edu wants software.microsoft.com

  38. DNS - domain name service • If the domain name is one of its own, ask the correct child • If the name is not one of its own, ask the parent com edu yahoo byu utah microsoft ee cs www students research software students.cs.byu.edu wants software.microsoft.com students asks cs

  39. DNS - domain name service • If the domain name is one of its own, ask the correct child • If the name is not one of its own, ask the parent com edu yahoo byu utah microsoft ee cs www students research software students.cs.byu.edu wants software.microsoft.com cs asks byu

  40. DNS - domain name service • If the domain name is one of its own, ask the correct child • If the name is not one of its own, ask the parent com edu yahoo byu utah microsoft ee cs www students research software students.cs.byu.edu wants software.microsoft.com BYU asks edu

  41. DNS - domain name service • If the domain name is one of its own, ask the correct child • If the name is not one of its own, ask the parent com edu yahoo byu utah microsoft ee cs www students research software students.cs.byu.edu wants software.microsoft.com edu asks com

  42. DNS - domain name service • If the domain name is one of its own, ask the correct child • If the name is not one of its own, ask the parent com edu yahoo byu utah microsoft ee cs www students research software students.cs.byu.edu wants software.microsoft.com com asks microsoft

  43. DNS - domain name service • If the domain name is one of its own, ask the correct child • If the name is not one of its own, ask the parent com edu yahoo byu utah microsoft ee cs www students research software students.cs.byu.edu wants software.microsoft.com microsoft knows and gives the answer

  44. DNS - making it fast • Each node remembers the most common requests for a day or two • Doesn’t need to ask again • Called “caching” com edu yahoo byu utah microsoft ee cs www students research software

  45. DNS - managing the data • Each node can manage and change its own children without consulting anyone else • Within 2 days of the changes, everyone’s cache has been updated com edu yahoo byu utah microsoft ee cs www students research software

  46. Other protocols • Use TCP/IP • WWW • Email • Instant messenger • FTP

  47. WWW • URL - “students.cs.byu.edu/index.html” • Send a message to DNS - “what is students.cs.byu.edu?” • Use IP address to send a message to “students.cs.byu.edu” • “GET index.html”

  48. Email - uses TCP/IP • send a message to “bill_gates@microsoft.com” • find my mail server “mail.cs.byu.edu” • message to “mail.cs.byu.edu” to: bill_gates@microsoft.com from: olsen@cs.byu.edu subject: Hi there • mail server forwards the message to “microsoft.com” • if no answer it will keep trying for about a week

  49. Networking Review • Sending bytes between computers • IP - sends a packet to a particular IP address • TCP - guarantees that packets are in correct order and not lost • DNS - uses a tree to convert domain names into IP addresses • WWW - uses TCP/IP • Email - uses TCP/IP

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