Which is better controlled access or contention explain

CH4

Short Answer Questions

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.

CH5

Short Answer

1. What does the network layer do? Where does it sit in relationship to the other four layers of our simplified network model?

2. What are the parts of TCP/IP and what do they do? Who is the primary user of TCP/IP?

3. Compare and contrast the three types of addresses used in a network.

4. What are the different classes of Internet addresses and how are they different?

5. What is a subnet and why do networks need them? What is a subnet mask?

6. How does dynamic addressing work? What benefits and problems does dynamic addressing provide?

7. What is address resolution? How does TCP/IP perform address resolution for network layer addresses? How does TCP/IP perform address resolution for data link layer addresses?

8. What is routing? How does decentralized routing differ from centralized routing? How does static routing differ from dynamic routing? When would you use static routing? When would you use dynamic routing? How does static routing differ from dynamic routing? When would you use static routing? When would you use dynamic routing?

9. What are the differences between connectionless and connection-oriented routing? Discuss this in detail. When might UDP be used? TCP? What is a virtual circuit? What is Quality of Service routing and why is it useful?

10. Compare and contrast unicast, broadcast, and multicast messages. Explain how multicasting works.

11. Explain how the client computer in the LAN figure in the book (Figure 5.15) would obtain the data link layer address of its subnet gateway.

12. Explain how TCP/IP works in a high level way, using a detailed diagram including the different roles of TCP vs. IP, and the times at which each function is utilized in the process.

13. List and describe five reasons why TCP/IP has become the predominant protocol for Internet level transport applications. What do you think is the future market share potential for proprietary standards? What are some limitations of TCP/IP in terms of future Internet growth capabilities?

14. What is a routing table? What is the simplest form of a routing table?

15. What is a virtual circuit?

16. Suppose a client computer wants to access a web page on a web server. Assume that it knows all of the IP addresses and data link layer addresses in the network, except those for the web server itself. Describe how the client would obtain the IP address for the web server.

17. What is ARP and how and why does it work? What is MAC address resolution and how does it work?

18. Suppose a client computer wants to access a web page on a web server. Assume that it knows all of the IP addresses and data link layer addresses in the network, except those for the web server itself. If the web server was on the same subnet as the client, how would the client obtain the data link layer address for the web server?

19. Under what conditions does decentralized dynamic routing provide better performance than decentralized static routing?

20. What is DHCP and why would network managers want to use it?

21. What four pieces of information does a computer using TCP/IP need in order to send messages using TCP/IP. Explain why each of these is required.

22. Suppose your manager asks you to discuss how the company’s backbone network functions in just about four paragraphs to take to senior management. How would you answer the question? Discuss two or three major points. Your manager doesn't understand technical terms so be sure to explain any jargon you use.

23. What is the difference between centralized routing and decentralized routing? What is the difference between static routing and dynamic routing? What is a distance vector algorithm and what is a link state algorithm? What is interior routing and what is exterior routing? Define and describe RIP, OSPF, EIGRP, BGP protocols using these terms.

24. Be able to convert back and forth between binary and decimal notation for IPv4 addresses.

25. Describe how Domain Name Server works and is hierarchically organized. What happens if a URL is not in a local DNS server?

List and describe the three ways that a network manager can connect to a router and configure and maintain it.

CH7

Short Answer

1. What does a NOS do? What are the major software parts of a NOS? What is the most important characteristic of a NOS? What are two NOS product names?

2. Describe CSMA, CD and CA. How does this work, in essence? Compare this to wireless LANS? How are they similar, and how are they different in terms of MAC?

3. Identify and describe the components of a data center.

4. What are two other names for NIC cards?

5. Describe in detail the difference between a hub and a switch in a LAN. Draw a diagram of each, and then mark it to show some of the points that you have made in your discussion of the differences. Discuss the difference between shared Ethernet and switched Ethernet in light of your answer.

6. Given a specific description of an Ethernet type, be prepared to answer questions regarding its speed, type of transmission and physical structure, e.g., 100BaseT, etc.

7. Define the three modes of switch operations.

8. What is the best practice Ethernet at the present time? Describe, and explain why this is best practice. What is the best practice wireless at the present time? Describe and explain why this is best practice. Would you install a wired or wireless Ethernet right now? Describe, if you were a manager, what your network of choice would be and why.

9. Discuss in detail how you would improve a LAN network’s performance, and what you would look for.

10. What is the difference in a logical and physical topology?

11. What are three reasons why Wi Fi has grown in popularity?

12. What is the “hidden node” problem, and what do you need to do about it in the best LAN design for wireless?

13. How might you as a network manager improve WLAN performance?

14. What devices are needed to build a wireless network?

15. Describe war-chalking, war-driving, and war-walking.

16. Compare a switched Ethernet to a wireless Ethernet. What are four essential differences between these two approaches to building a LAN? Give three reasons why a switched Ethernet is preferable to wireless. Three reasons why wireless might be preferred to switched?

17. Select three different types of IEEE 802.11 and describe when it might be best to use each one.

18. Discuss wireless network security. What are some of the critical problems, what are some of the defenses against these problems? List five potential weaknesses in security and five potential solutions to these perceived weaknesses.

19. Describe how you might secure your home wireless network.

20. What is the purpose of the e-commerce edge?