Exercise 4             Name _____________ Pts __/13

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1. (1 pt)    Under what conditions would an open-loop protocol such as an error-correcting Hamming code be preferable to the feedback type protocols discussed throughout this chapter?
 
 
 
 

2. (1 pt)    Suppose that a stop-and-wait protocol was used on a channel is 1 second propagation delay and sender frames of 5 seconds. The receiver must fully receive the frame before sending an acknowledgment. The size of the acknowledgment can be ignored. What is the channel utilization?
 
 
 

3. (1 pt)    A channel has a propagation delay of  1 second. The receiver must fully receive the frame before sending an acknowledgment. The size of the acknowledgment can be ignored. For what range of frame sizes (in seconds) does stop-and-wait utilize at least 80% of the channel?
 
 
 
 

4. (4 pt)    Using the below diagram, starting at 1 for each list the sender and receiver state numbers that would be entered given that:

Sender                                                                    Receiver


  5. (6 pt) Using p-persistent, consider 2 nodes - X and Y. If Y is twice as likely to transmit as X, is its throughput twice that of X's? Why or why not? Is it possible to create (mathematically) conditions that would accomplish this?

 

 


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