## Written Exercise #1

This exercise is meant to help you review materials in the link layer, network layer, and transport layer. It can also help you to prepare for the midterm exam, but note that it does not necessarily contain all materials that you need to review for the midterm. You should not turn in your solution (and we will not grade it even if you do). We will not post the solutions either.

This exercise includes a number of end-of-chapter problems in the textbook by Kurose and Ross (sixth edition). Note that these are end-of-chapter Problems, not Review Questions.

1. Chapter 5 Problem 5, note that the problem states the wrong bit number for the generator.
2. Chapter 5 Problem 8.
3. Chapter 5 Problem 13.
4. Chapter 5 Problem 18.
6. Chapter 4 Problem 26.
7. Chapter 4 Problem 28.
8. Chapter 4 Problem 29.
9. Network latency triangular inequality.
1. Consider a network that employs shortest-path routing (e.g., the routing path between two nodes is the shortest-latency path between them). For three machines A, B, and C, let lAB be the network latency between A and B; let lBC be the network latency between B and C; let lAC be the network latency between A and C. Is it possible for lAB + lBC < lAC? Explain your answer.
2. Consider the practical wide-area Internet routing. lAB, lBC, and lAC are defined as in (a). Is it possible for lAB + lBC < lAC? Explain your answer.
10. Chapter 3 Problem 3.
11. Chapter 3 Problem 5.
12. Chapter 3 Problem 15.
13. Chapter 3 Problem 25.
14. Chapter 3 Problem 41.
15. A cumulative acknowledgment of packet X tells the sender that all data up to packet X has been received without error. A selective acknowledgment of packet X only indicates that packet X has been received without error.
1. Describe a situation that selective acknowledgment can lead to higher network efficiency than cumulative acknowledgment does.
2. Describe a situation that cumulative acknowledgment can lead to higher network efficiency than selective acknowledgment does.