Fall 2018 CSE30264 Homework 5


Total Points: 60 points
Scope: Chapters 5, 6
Due: December 5, 2018 by class time
Grouping: To be completed individually


Problems

Problem 1: [10 points] What is the end-to-end argument in network system design? Give an example we studied in lectures that does not exactly follow this argument and explain why.

Problem 2: [10 points] Please explain why a potential deadlock between the sender and receiver could happen if the advertised window size in TCP goes to zero? Describe the solution of TCP to address this problem and the rationale behind this solution.

Problem 3: [18 points: 6 points to justify why R1 cannot be congested and 7 points for (b) and 5 points for (c)] Consider the arrangement of hosts H and routers R in the following figure. All links are full-duplex, and all routers are faster than their links. Show that
  1. R1 cannot become congested

  2. We can find a traffic pattern that congests router R2 alone

  3. We can find a traffic pattern that congests router R7 alone



Problem 4: [22 points: 6 points for (a) 8 points each for (b) and (c)] Suppose that a router has three input flows and one output flow. It receives the packets listed in the Table below, all at about the same time, in the order listed, during a period in which the output port is busy but all queues are otherwise empty. Give the order in which the packets are transmitted, assuming
  1. Round robin

  2. Fair queuing

  3. Weighted queuing with flow 1 having weight 2, flow 2 having weight 3 and flow 3 having weight 1

Note: You can break the ties by using the flow id: the packet with smaller flow id gets transmitted first.




Submission Instructions

Create a PDF file containing your answers. Place your name at the beginning of the file. Copy the file into dropbox/hw5/hw5.pdf.