1. Computer Networks Fall, 2007 Prof Peterson

2. CIS 235: Networks Fall, 2007 Western State College  What are the main layers? What happens at each?

3. CIS 235: Networks Fall, 2007 Western State College  What happens at this layer?  What sort of concerns do we worry about at this level in the system?

4. CIS 235: Networks Fall, 2007 Western State College The OSI model is a popular way to describe networking. It adds two extra layers to the ones we just described: Presentation and Session. These concerns are not really separate from the application layer in this class

5. CIS 235: Networks Fall, 2007 Western State College

6. How does this model work in other systems? Post office: What is “application layer”? What is the “transport layer”? What is the “network layer”? What is the “link layer”? What is the “physical layer”?

7. CIS 235: Networks Fall, 2007 Western State College Consider a packet going from my laptop to the campus email system containing a message I’m emailing. How does it go through the layers on each device? Where in the machine is the code that implements each layer?

8. CIS 235: Networks Fall, 2007 Western State College  What is a link layer switch?  What is encapsulation?  Where does encapsulation occur at the application level?

9. CIS 235: Networks Fall, 2007 Western State College  How can a machine be attacked via the Internet?  What is malware?  How can network infrastructure be attacked?  How can bad guys appear to be good?

10. CIS 235: Networks Fall, 2007 Western State College  What are the basic ideas of networking?  What’s a protocol?  How do packets move around?  What sorts of traffic are there?  How is the Internet organized and governed?  What sort of hardware makes up a network?  What sort of things do we need to understand in relation to performance?  What issues does each level of the protocol stack deal with?