Data Link Layer


Question 1
Suppose two hosts are connected by a point-to-point link and they are configured to use Stop-and-Wait protocol for reliable data transfer. Identify in which one of the following scenarios, the utilization of the link is the lowest.
A
Longer link length and lower transmission rate
B
Longer link length and higher transmission rate
C
Shorter link length and lower transmission rate
D
Shorter link length and higher transmission rate
GATE CSE 2023   Computer Network
Question 2
Consider a 100 Mbps link between an earth station (sender) and a satellite (receiver) at an altitude of 2100 km. The signal propagates at a speed of 3 \times 10^8 m/s. The time taken (in milliseconds, rounded off to two decimal places) for the receiver to completely receive a packet of 1000 bytes transmitted by the sender is
A
15.06
B
54.25
C
7.08
D
4.25
GATE CSE 2022   Computer Network


Question 3
Consider a network using the pure ALOHA medium access control protocol, where each frame is of length 1,000 bits. The channel transmission rate is 1 Mbps (=10^6 bits per second). The aggregate number of transmissions across all the nodes (including new frame transmissions and retransmitted frames due to collisions) is modelled as a Poisson process with a rate of 1,000 frames per second. Throughput is defined as the average number of frames successfully transmitted per second. The throughput of the network (rounded to the nearest integer) is ______________
A
180
B
160
C
135
D
115
GATE CSE 2021 SET-2   Computer Network
Question 4
Consider the cyclic redundancy check (CRC) based error detecting scheme having the generator polynomial X^3+X+1. Suppose the message m_4m_3m_2m_1m_0=11000 is to be transmitted. Check bits c_2c_1c_0 are appended at the end of the message by the transmitter using the above CRC scheme. The transmitted bit string is denoted by m_4m_3m_2m_1m_0c_2c_1c_0. The value of the checkbit sequence c_2c_1c_0 is
A
101
B
110
C
100
D
111
GATE CSE 2021 SET-2   Computer Network
Question 5
Consider the sliding window flow-control protocol operating between a sender and a receiver over a full-duplex error-free link. Assume the following:

The time taken for processing the data frame by the receiver is negligible.
The time taken for processing the acknowledgement frame by the sender is negligible.
The sender has infinite number of frames available for transmission.
The size of the data frame is 2,000 bits and the size of the acknowledgement frame is 10 bits.
The link data rate in each direction is 1 Mbps (= 10^6 bits per second).
One way propagation delay of the link is 100 milliseconds.

The minimum value of the sender's window size in terms of the number of frames, (rounded to the nearest integer) needed to achieve a link utilization of 50% is _____________
A
82
B
51
C
44
D
65
GATE CSE 2021 SET-1   Computer Network




There are 5 questions to complete.

14 thoughts on “Data Link Layer”

  5. In Qestion no 13 data is missing
    propagation speed of link is ( 2×10^8 meter per second ) not millisecond please correct it.

    Reply

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