CS 487 Third Homework Assignment

Due Tuesday September 26 in class.

1. W & V Problem 2.18

2. W & V Problem 2.20

3. W & V Problem 2.21

4. W & V Problem 2.22

5. W & V Problem 2.23

6. A channel has a bit rate of 4 kbps and a propagation
delay of 20 ms. For what range of frame (packet) sizes
does stop and wait give an efficiency of at least 50%?
You can assume that errors are rare.

7. Consider an error-free 64-kbps satellite channel used to
send 512-byte data frames in one direction with very short
acknowledgements coming back the other way. What is the
maximum throughput for window sizes of 1, 7, 15, and 127?

8. Consider a pipeline protocol with n bit sequence
numbers, 0,1,...., 2^n-1. Show that we can only use
sequence numbers 0, 1, ..., 2^n-2. Hint: Consider what
happens if  the sender sends out the maximum number 
of frames and receives two consectutive acks with the
highest sequence number.