1. Skills: none Concepts: host, TCP/IP communication software, TCP/IP layers, TCP/IP functions, TCP/IP protocols This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 License. TCP/IP communication software

2. Where does this topic fit? Internet concepts – Applications – Technology (communication) – Implications Internet skills – Application development – Content creation – User skills

3. TCP/IP from the outside Application Program, for example, a Web client Application Program, for Example, a Web server A TCP/IP network

4. 001010101 LAN Internet Router A closer look

5. TCP/IP the very big picture Layer Function Application programs Do useful work like Web browsing, email, and file transfer TCP/IP communication software Handle communication between the client and server

6. TCP/IP is a standard

7. LayerFunction Application Do useful work like Web browsing, email, and file transfer Transport Handle communication between the client and server Internet Data link Physical TCP/IP a closer look

8. Function of each layer LayerFunction ApplicationDo useful work like Web browsing, email, and file transfer TransportTransport data between application programs running on two hosts InternetRoute packets between networks (inter network) Data linkSend data within the local area network PhysicalSpecify hardware characteristics and ways to differentiate between ones and zeros

9. Protocols at each layer LayerProtocol ApplicationMany depending upon the application TransportTCP or UDP InternetIP Data linkEthernet and WiFi most common PhysicalMany wireless, copper wire, optical fiber, etc.

10. Application (do useful work) Transport (app to app communication) Internet (net to net communication) Physical (LAN, WAN links) Data link (LAN communication) TCP/IP hierarchy -- responsibilities

11. Application (many) Transport (UDP, TCP) Internet (IP) Physical (LAN, WAN links) Data link (Ethernet, WiFi) TCP/IP hierarchy -- protocols

12. Application Transport Internet Data link Network Access or Network Interface Physical Alternate terminology

13. Summary LayerFunction ApplicationDo useful work like Web browsing, email, and file transfer TransportTransport data between application programs running on two hosts InternetRoute packets between networks (inter network) Data linkSend data within the local area network PhysicalSpecify hardware characteristics and ways to differentiate between ones and zeros

14. Self-study questions 1.We have a local area network at school that connects to the Internet. Do you have a LAN at home? How many computers connect to it? How does it connect to the Internet? 2.When you connect to the Internet using a mobile device like a phone or a tablet, are you connecting to a network that is connected to the Internet? Explain. 3.We saw that there were two commonly protocols at the transport layer – TCP for reliable communication and UDP for fast, but unreliable communication. Which would an application programmer use for a file-transfer program? Which would an application programmer use for a streaming video program? Explain your answers.

15. Application Physical Do you recall the names of the TCP/IP protocol layers?

16. Do you recall the functions of the software at each layer? Application: Transport: Internet: Data link: Physical:

17. Do you recall the protocol(s) used at each layer? Application: Transport: Internet: Data link: Physical:

18. Resources Terminology used by selected authors: http:/en.wikipedia.org/wiki/Internet_Protocol_Suite#Layer_names_and_ number_of_layers_in_the_literature