EXAM AID NOTES ON LAN SYSTEMS
-Vasuki M. Basavanahalli
1. The objective of this note (along with the slides) is to act as an aid for your preparation for the Exam-2.
2. This does not replace your effort of going through the Dr Lin’s slides as well book as the book thoroughly.
3. I have prepared some slides, which will hopefully cement some of the concepts, and they are pretty much self-explanatory in nature. (That is why I have not come out with a full-fledged written summary of this chapter.)
4. I have come out with questions and concepts that you should look into in this chapter. I have also categorized these questions for easy reference.
5. You may not be able to answer some of these questions, but don’t panic. These are only meant for reinforcing and re-looking into some of the concepts into the book again. You may use these questions for future reference as well.
6. These questions are pretty exhaustive in coverage, and it is my belief that it should be able to cover this portion of the exam very well (along with my slides.)
7. All the Best for your exams!
Basic Questions:
1. What trends have forced us to develop High speed LANs? What are the commercial products available to meet these needs? Compare and contrast their advantages and disadvantages? (Should set up the ground for this chapter).
2. What are server farms and Power Workgroups? Explain their utility clearly?
3. What is the data transmission rate achievable in Ethernet and Fiber Channel?
4. What is the reason of popularity of Ethernet vs. Token Ring?
5. What are the different IEEE standards? (Please know them clearly-like 802.3, 802.5 etc.)
Ethernet:
1. Who were instrumental in developing Ethernet?
2. What are the advantages and disadvantages of Ethernet?
3. Explain CSMA.
4. Explain CD.
5. What is a Fast Ethernet? How “Fast” is it? What is a Gigabit Ethernet?
6. What does 10 Base5 or 10BaseT mean?
7. What are the different Physical alternatives you can have for Ethernet?
8. What are the transmission medium options available for Fast Ethernet?
9. How does Fast Ethernet differ from 10Base-T, other than the data rate?
10. Explain each of the elements of “Ethernet 802.3 10Base-T” and “Ethernet 802.3 100 Base-TX”. At what layers are these standards defined? Why are many organizations upgrading from 10Base-T to 100Base-TX? Why is this upgrade easy and inexpensive?
11. How many wires are there in 802.3 10Base-T/100 Base-TX wiring bundle? How many are actually used in transmission? How would you answer if someone asked you what “Cat-5” means?
12. What is the baud rate of Ethernet 10 Base-T networks?
13. In Ethernet 100Base-TX, how many class-1 hubs can you have? How many class-2 Hubs? What is the maximum distance between class-2 hubs?
14. The 100Base-TX standard only allows a distance span of about 200 meters because of collision detection problems. How does a gigabit Ethernet avoid even smaller distance limitations because of its ten-times-higher speed?
15. How do switches traditionally differ from Bridges?
16. Explain the physical connection in 10Base5. What are the distance limits in 10Base5?
17. Explain the physical connection in 10Base2. What are the distance limits in 10Base2?
18. In 10Mbps Ethernet LANs, what are the limits for the number of segments and repeaters linking the two farthest stations?
19. What are the 3 forms of switches? What is the relative advantage of each of them?
20. Define Inter-switch Trunking? What is its advantage?
21. Why is Ethernet normally half-duplex? Why can Ethernet switches be full duplex? For full duplex switching, do you have to change the NIC?
22. How do Ethernet switches restrict traffic to a single path between stations?
23. What are the advantages of Ethernet switches compared to ATM switches?
Token Ring
1. Who was instrumental in developing Token Ring?
2. Explain the medium access control in Token Ring?
3. What is the principal advantage and disadvantage of using a Token Ring?
4. Explain the major-risks associated with 802.5 Token Ring Network and how the standard handles each one of them?
5. What is the status of Token Ring Networks today?
6. What is the difference between traditional token ring MAC and dedicated token ring?
7. Under heavy loads, how do the behavior of CSMA/CD and token ring differ?
Fibre Channel
1. What is a fibre channel? What is its biggest advantage? Disadvantage?
2. What are the key elements of Fibre Channel? What is a fabric? What are N-Ports? What are F-ports?
3. What is the name of the industry consortium leading the development of fibre channel?
4. What are the topology options for Fibre channel?
5. List the five levels of Fibre Channel and the functions of each level?
6. What are the prospects for Fibre Channel?
Wireless LANs
1. What are the different Wireless LAN applications?
2. What are the typical Wireless LAN requirements?
3. What is the IEEE standards covering Wireless LAN?
4. What is the difference between single-cell and multiple-cell wireless LANs?
5. What services are provided by IEEE 802.11?
6. What are the two modes of operation in 802.11 wireless LANs? What are the two ways of controlling when a station may transmit in 802.11?
7. Explain CSMA/CA+ ACK.
8. Explain DSSS.
9. Explain FHSS.
10. In ISM (Industrial, scientific and medical) band, why is it possible to build wireless LANs that interfere with one another? In spread spectrum transmission, explain graceful degradation and explain how it gives firms time to negotiate if their wireless networks interfere.
11. Explain typical wireless LAN applications? What are access points? Explain about the security and future of wireless LANs?