1. CSCE 515: Computer Network Programming Chin-Tser Huang huangct@cse.sc.edu University of South Carolina

2. 1/11/2005(C) 2005 Chin-Tser Huang2 About Me Chin-Tser Huang Ph.D. in Computer Sciences, 2003, University of Texas at Austin My second year with USC Research in network security, network protocol design and verification, distributed systems My web page can be found at http://www.cse.sc.edu/~huangct http://www.cse.sc.edu/~huangct

3. 1/11/2005(C) 2005 Chin-Tser Huang3 About the Course A course focusing on programming aspects of computer networks Course will be divided into two parallel themes Network architecture and protocols Network programming issues in Java

4. 1/11/2005(C) 2005 Chin-Tser Huang4 Course Information Online http://www.cse.sc.edu/~huangct/CSCE 515S05/index.htm http://www.cse.sc.edu/~huangct/CSCE 515S05/index.htm Look for information about Topics and schedule Projects and homeworks Grading rules Useful links

5. 1/11/2005(C) 2005 Chin-Tser Huang5 Why You Should Take This Course Network applications are becoming more and more important to our life You want to have a clear understanding of network architecture and TCP/IP suite You also want to have good ability in network-based software design and implementation You have chances to implement the skills learned in the classes

6. 1/11/2005(C) 2005 Chin-Tser Huang6 Your Best Strategy Come to every lecture Keep yourself exposed to articles related to network protocols and network programming Finish each assigned reading before coming to class Do not wait till last minute to prepare for exam or work on project Enjoy the fun!

7. 1/11/2005(C) 2005 Chin-Tser Huang7 What Is Going On… …when your computer receive a message from your partner? m Internet x y ?

8. 1/11/2005(C) 2005 Chin-Tser Huang8 What Is Going On… First, your partner needs to construct the message and send it to the network m Internet x y

9. 1/11/2005(C) 2005 Chin-Tser Huang9 What Is Going On… Then, routers in the Internet collaborate to forward the message toward your computer m Internet x y

10. 1/11/2005(C) 2005 Chin-Tser Huang10 What Is Going On… Finally, your computer needs to determine which application should receive the message m Internet x y ? telnet ftp browser

11. 1/11/2005(C) 2005 Chin-Tser Huang11 Other Issues Beyond This Multicast or broadcast? Proxy? Security features? …

12. 1/11/2005(C) 2005 Chin-Tser Huang12 Network Protocols Abstractions of communication between two processes over a network Define message formats Define legitimate sequence of messages Take care of physical details of different network hardware and machines Separate tasks in complex communication networks For example, FTP and ARP

13. 1/11/2005(C) 2005 Chin-Tser Huang13 Protocol Layering Many problems need to be solved in a communication network These problems can be divided into smaller sets and different protocols are designed for each set of problem Protocols can be organized into layers to keep them easy to manage

14. 1/11/2005(C) 2005 Chin-Tser Huang14 Properties of Protocol Layer Functions of each layer are independent of functions of other layers Thus each layer is like a module and can be developed independently Each layer builds on services provided by lower layers Thus no need to worry about details of lower layers -- transparent to this layer

15. 1/11/2005(C) 2005 Chin-Tser Huang15 Protocol Stack: OSI Model Application Presentation Session Transport Network Data link Physical

16. 1/11/2005(C) 2005 Chin-Tser Huang16 Communicating End Hosts Application Presentation Session Transport Network Data link Physical Application Presentation Session Transport Network Data link Physical Network Data link Physical Host Router

17. 1/11/2005(C) 2005 Chin-Tser Huang17 Next Class Seven layers in OSI reference model Corresponding Internet architecture Application programming interface (API) Read TI Ch. 1, JNP Ch. 1