Fall 2018 CSE30264 Homework 3


Total Points: 60 points
Scope: Chapters 3
Due: November 5 2018, by class time
Grouping: To be completed individually

Problems

Problem 1: [22 points: 2 points for (a), 4 points each for (b)-(f)] Using the example network below, give the virtual circuit table for all the switches after each of the following connections is established. Assume that the sequence of connections is cumulative; that is, the first connection is still up when the second connection is established, and so on. Also, assume that the VCI assignment always picks the lowest unused VCI on each link, starting with 0, and that VCI is consumed for both directions of a virtual circuit.
  1. Host B connects to host J

  2. Host H connects to host G

  3. Host C connects to host B

  4. Host A connects to host F

  5. Host I connects to host G

  6. Host G connects to host C



Problem 2: [12 points, 3 points for each switch's forwarding table] Consider the arrangement of learning bridges shown in the following figure. Assuming all are initially empty, give the forwarding tables for each of the bridges B1-B4 after the following transmissions: (Note: You only need to show the final forwarding tables after all three transmissions: A->C, C->A, D->C)

Problem 3: [16 points: 8 points for the correct spanning tree; 8 points for the correct explanation] Give the extended LAN shown in the following figure, indicate which ports are not selected by the spanning tree algorithm. (Please also explain how you decide which port in the extended LAN will not be used in the spanning tree. A correct spanning tree without explanation will only get half credits).


Problem 4: [10 points] Give the spanning tree generated for the extended LAN shown in the following figure, and discuss how ties are resolved.(Note: "discuss how ties are resolved" means: draw all possible spanning trees if any tie exists when you build the spanning tree of the extended LAN).



Submission Instructions

Create a PDF file containing your answers. Place your name at the beginning of the file. Copy the file into dropbox/hw3/hw3.pdf.