Andrew S. Tanenbaum Edition 5th Exercise 6 Question 30 (Page No. 609)

Question

Consider the effect of using slow start on a line with a 10-msec round-trip time and no
congestion. The receive window is 24 KB and the maximum segment size is 2 KB.
How long does it take before the first full window can be sent?

Answer 1

Starting with window size = 1 segment = 2 KB At RTT 1 (10 ms), cwnd = 4 KB At RTT 2 (20 ms), cwnd = 8 KB At RTT 3 (30 ms), cwnd = 16 KB At RTT 4 (40 ms), cwnd = 24 (limited by receiver window) Answer = 40 ms

Answer 2

RCWD=24/2=12

Thresh hold=12/2=6 set

1 ,2, 4, 6, 7, 8, 9, 10, 11, 12

total 9*10=90 ms before send full window 12

 

Comments

No congestion is given in que so it should always work on slow start mode