Interactive end-of-chapter exercises


Computing end-end delay (transmission and propagation delay)

Consider the figure below, with three links, each with the specified transmission rate and link length.




Assume the length of a packet is 4000 bits. The speed of light propagation delay on each link is 3x10^8 m/sec

Round your answer to two decimals after leading zeros



Question List


1. What is the transmission delay of link 1?

2. What is the propogation delay of link 1?

3. What is the total delay of link 1?

4. What is the transmission delay of link 2?

5. What is the propogation delay of link 2?

6. What is the total delay of link 2?

7. What is the transmission delay of link 3?

8. What is the propogation delay of link 3?

9. What is the total delay of link 3?

10. What is the total delay?




Solution


Link 1 transmission delay = L/R = 4000 bits / 1000 Mbps = 4.00E-6 seconds

Link 1 propagation delay = d/s = ()3 Km) * 1000 / 3*10^8 m/sec = 1.00E-5 seconds

Link 1 total delay = d_t + d_p = 4.00E-6 seconds + 1.00E-5 seconds = 1.40E-5 seconds

Link 2 transmission delay = L/R = 4000 bits / 1000 Mbps = 4.00E-6 seconds

Link 2 propagation delay = d/s = ()5000 Km) * 1000 / 3*10^8 m/sec = 0.017 seconds

Link 2 total delay = d_t + d_p = 4.00E-6 seconds + 0.017 seconds = 0.017 seconds

Link 3 transmission delay = L/R = 4000 bits / 100 Mbps = 4.00E-5 seconds

Link 3 propagation delay = d/s = ()2 Km) * 1000 / 3*10^8 m/sec = 6.67E-6 seconds

Link 3 total delay = d_t + d_p = 4.00E-5 seconds + 6.67E-6 seconds = 4.67E-5 seconds

The total delay = d_L1 + d_L2 + d_L3 = 1.40E-5 seconds + 0.017 seconds + 4.67E-5 seconds = 0.017 seconds



That's incorrect

That's correct

The answer was: 4.00E-6

Question 1 of 10

The answer was: 1.00E-5

Question 2 of 10

The answer was: 1.40E-5

Question 3 of 10

The answer was: 4.00E-6

Question 4 of 10

The answer was: 0.017

Question 5 of 10

The answer was: 0.017

Question 6 of 10

The answer was: 4.00E-5

Question 7 of 10

The answer was: 6.67E-6

Question 8 of 10

The answer was: 4.67E-5

Question 9 of 10

The answer was: 0.017

Question 10 of 10

Try Another Problem

We gratefully acknowledge the programming and problem design work of John Broderick (UMass '21), which has really helped to substantially improve this site.

Copyright © 2010-2022 J.F. Kurose, K.W. Ross
Comments welcome and appreciated: kurose@cs.umass.edu