CSCI 4171/CSCI 6704 NETWORKS

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CSCI 4171/CSCI 6704

NETWORKS

ASSIGNMENT NO.3

Exercise 1: In this exercise, you will write a simple program to simulate the bridge-processing flowchart for a bridge that we discussed in the lectures (Please see the flowchart given on Page 3).

You are given a text file (BridgeFDB.txt) that contains the forwarding database of a bridge with four ports. The entries in the text file are arranged as shown below:

You are given another text file (RandomFrames.txt) that contains the source MAC address, the destination MAC address of a random frame on the network that the bridge is connected to, and the port number of the bridge that it arrives on. The entries in this text file are arranged as shown below:

Your program should read the two text files, and for each random frame, it should make a decision either to forward/discard/broadcast the frame. If the source MAC address is not in the database, then it should update it.

Ignore the CRC error detection part (that is, assume that the frames are error free). Store the resulting output in another text file (BridgeOutput.txt).

Your output would look something like this (for the above three sample frames).

Note: The reason the last frame is broadcast is because the entry 00-00-4f-31-fa-fb is not in the FDB. You should keep track of the updated FDB and also submit that as part of your output. Your program will be tested using the sample BridgeFDB.txt and RandomFrames.txt.

The BridgeFDB.txt and RandomFrames.txt can be downloaded along with the assignment from the Brightspace portal.

You may use Java, C, C++ or Python as your programming language.

Exercise 2: Consider the bridge configuration shown in the figure below. Bridges B1 and B2 connect two LANs, and A and B are hosts on one LAN. This is one of the configurations that results in a classic problem in bridges called the bridge loop problem that results in a race condition. One of the solutions to this problem is then bridge spanning tree protocol. Conduct an online search to understand this problem, and how it is fixed. Write a short report (approximately one page, 12 point, single font including citations) on your study of the problem and its solution.

What to submit: One zip file containing the following:

a) Source code for Exercise 1

b) Text file/PDF containing the output for Exercise 1

c) BridgeFDB.txt file (updated) for Exercise 1

d) PDF for Exercise 2

BBridge Operation Flowchart (including Bridge Learning)

Bridge B