資料通訊實戰測試 2
Problem 1
What are the three types of HDLC frame?
- I
- U
- S
Problem 2
What are the three types of IEEE802.11("Wi-Fi") frames that correspond to the answer of problem 1, respectively?
- Data(1A)
- Management(1B)
- Control(1C)
Problem 3
Answer the following questions on MAC protocols.
- What is the difference between ALOHA and CSMA？
Hint: name the most important protocol feature that differentiates them
Answer: Carrier Sense
- How is CSMA/CA different from CSMA/CD in terms of random backoff?
Hint: Think of when the random backoffs happen in these two methods
Answer: It backs off *before* transmitting instead of after.
Problem 4
If W1=[-1],what is the Walsh table W4?
Hint: W4 can be used to assign codes to four stations at the maximum
Answer:
Problem 5
Today's Ethernet does not use CSMA/CD
- What is the fundamental reason?
Hint: think about "CD"
Answer: There is no collision any more.
- What feature made the answer to question1 possible?
Hint: It's not simplex
Answer: full-duplex communication with switch