First Semester 2020-2021
Course Work 1
Using MS Word Equation Editor tool when necessary.
Q1.
a. Two communicating devices are using a single-bit even parity check for error
detection. The transmitter sends the byte 10101010 and, because of channel noise,
the receiver gets the byte 10011010. Will the receiver detect the error? Why or why
not?
b. What is function of Minimum of Hamming Distance in data communication. Find the
Hamming pairwise distances among the following codewords:
(i) 00000, 10101, 01010
(ii) 000000, 010101, 101010, 110110
Q2.
a. In a CRS error-detecting scheme, chose 𝑃(𝑥) = 𝑥 4 + 𝑥 + 1. Encode the bits
10010011011.
b. Suppose the channel introduces an error pattern 100010000000000 (i.e., a flip from
1 to 0 or from 0 to 1 in position 1 and 5). What is received? Can the error be
detected?
c. Repeat part (b) with error pattern 100110000000000.
Q3.
Consider the use of 1000-bit frames on a 1-Mbps satellite channel with a 270-ms delay.
What is the maximum link utilization for
a. Stop-and-wait flow control?
b. Continuous flow control with a window size of 7?
c. Continuous flow control with a window size of 127?
d. Continuous flow control with a window size of 255?
Q4.
Two neighbouring nodes (A and B) use a sliding-window protocol with a 3-bit sequence
number. As the ARQ mechanism, go-back-N is used with a window size of 4. Assuming A is
transmitting and B is receiving, show the window positions for the following succession of
events:
a. Before A sends any frames
b. After A sends frames 0, 1, 2 and receives acknowledgment from B for 0 and 1
c. After A sends frames 3, 4, and 5 and B acknowledges 4 and the ACK is received by A
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Q5.
Create the following topology in your Cisco Packet Tracer
Note:
Follow the following instructions carefully and strictly. Your deviation from the instructions
may lead to wrong answer.
(a) Name your computers as PC1, PC2, …PC4 as shown the diagram
(b) Name switch SW1 with your fist name and switch SW2 with your second name
(c) Configure static IP addresses for PC1 as 192.168.1.1, PC2 as 192.168.1.2, PC3 as
192.168.1.3 and PC4 as 192.168.1.4
(d) Write down the entries of the ARP cache of both PC1 and PC2
(e) Write down the entries of the Mac Address tables of the two switches
(f) Click on the simulation button located at the bottom right of your screen
(g) Using PC1, issue a ping command to PC3
(h) Write down the first 10 packet events starting from the first ICMP packet of PC1 in
your simulation output.
(i) Describe each of the events listed in (h)
(j) Write down the entries of the ARP cache of both PC1 and PC2
(k) Write down the entries of the Mac Address tables of the two switches
(l) Using PC2, issue a ping command to PC4
(m) Write down the first 10 packet events starting from the first ICMP packet of PC2 in
your simulation output.
(n) Describe each of the events listed in (h)
(o) Write down the entries of the ARP cache of both PC1 and PC2
(p) Write down the entries of the Mac Address tables of the two switches
Submit your packet tracer topology file with your firstname_IndexNo as the file name.
Include your answers to the following questions in your answer document.
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