1. What does the data link layer do? What are its primary responsibilities? Where does the data link layer sit in terms of the simplified five layer network model?

1. What does the data link layer do? What are its primary responsibilities? Where does the data link layer sit in terms of the simplified five layer network model?

2. What is media access control and why is it important? What are two examples of controlled access methods and contention based media access methods? When might one access method be preferred over another in a network, and why? Under what conditions do contention-based media access control techniques outperform controlled-access techniques (i.e., have lower response time)? Explain.

3. Compare and contrast roll call polling, hub polling (or token passing), and contention. Which is better, hub polling or contention? Explain.

4. Errors normally appear in ______________________________, which is when more than one data bit is changed by the error-causing condition. Is there any difference in the error rates of lower speed lines and of higher speed lines? What kinds of lines are more prone to errors?

5. Briefly define noise. Describe five types of noise and the underlying causes of this noise. Which type of noise is likely to pose the greatest problem to network managers? What does error look like in a data network?

6. How do amplifiers differ from repeaters?

7. What are three ways of reducing errors and the types of noise they affect?

8. Describe three approaches to detecting errors, including how they work, the probability of detecting an error, and any other benefits or limitations.

9. Briefly describe how even parity and odd parity work. Give an example of even parity with a 7-bit ASCII code, for the following: 0110110, using a 0 start bit and a 1 stop bit.

10. How does cyclical redundancy checking work?

11. How does forward error correction work? How is it different from other error correction methods? Under what circumstances is forward error correction desirable? What is one type of forward error correction by name? Given a diagram like that in the text of forward error correction, be able to explain how the system works.

12. Compare and contrast stop-and-wait ARQ and continuous ARQ.

13. Describe from a high level perspective the packet layout for SDLC, Ethernet, and PPP.

14. What is transparency?

15. What is transmission efficiency? How do information bits differ from overhead bits? What are three issues which might effect packet throughput rates? Which is better for file transfer, large packet sizes or small packet sizes?

16. What is asynchronous transmission v. synchronous transmission? Describe one protocol of each type.

17. Think about a recent world impact event and how useful the technologies of communications might have been related to helping people impacted by that event (Hurricane Katrina, Pakistan earthquakes, or some other large world event). How might telecom have a positive role in large scale human events? Use insight gained from the technological underpinnings provided in the course. Be creative.