Transport Layer Protocol


Question 1
Suppose you are asked to design a new reliable byte-stream transport protocol like TCP. This protocol, named myTCP, runs over a 100 Mbps network with Round Trip Time of 150 milliseconds and the maximum segment lifetime of 2 minutes.
Which of the following is/are valid lengths of the Sequence Number field in the myTCP header?
A
30 bits
B
32 bits
C
34 bits
D
36 bits
GATE CSE 2023   Computer Network
Question 2
Consider the data transfer using TCP over a 1 Gbps link. Assuming that the maximum segment lifetime (MSL) is set to 60 seconds, the minimum number of bits required for the sequence number field of the TCP header, to prevent the sequence number space from wrapping around during the MSL is
A
31
B
32
C
33
D
34
GATE CSE 2022   Computer Network


Question 3
Consider the three-way handshake mechanism followed during TCP connection establishment between hosts P and Q. Let X and Y be two random 32-bit starting sequence numbers chosen by P and Q respectively. Suppose P sends a TCP connection request message to Q with a TCP segment having SYN bit =1, SEQ number =X, and ACK bit =0. Suppose Q accepts the connection request. Which one of the following choices represents the information present in the TCP segment header that is sent by Q to P?
A
SYN bit =1, SEQ number =X+1, ACK bit =0, ACK number =Y, FIN bit =0
B
SYN bit =0, SEQ number =X+1, ACK bit =0, ACK number =Y, FIN bit =1
C
SYN bit =1, SEQ number =Y, ACK bit =1, ACK number =X+1, FIN bit =0
D
SYN bit =1, SEQ number =Y, ACK bit =1, ACK number =X, FIN bit =0
GATE CSE 2021 SET-2   Computer Network
Question 4
Consider two hosts P and Q connected through a router R. The maximum transfer unit (MTU) value of the link between P and R is 1500 bytes, and between R and Q is 820 bytes.
A TCP segment of size 1400 bytes was transferred from P to Q through R, with IP identification value as 0x1234. Assume that the IP header size is 20 bytes. Further, the packet is allowed to be fragmented, i.e., Don't Fragment (DF) flag in the IP header is not set by P.
Which of the following statements is/are correct?
[MSQ]
A
Two fragments are created at R and the IP datagram size carrying the second fragment is 620 bytes.
B
If the second fragment is lost, R will resend the fragment with the IP identification value 0x1234.
C
If the second fragment is lost, P is required to resend the whole TCP segment.
D
TCP destination port can be determined by analysing only the second fragment.
GATE CSE 2021 SET-1   Computer Network
Question 5
A TCP server application is programmed to listen on port number P on host S. A TCP client is connected to the TCP server over the network.
Consider that while the TCP connection was active, the server machine S crashed and rebooted. Assume that the client does not use the TCP keepalive timer. Which of the following behaviors is/are possible?
[MSQ]
A
If the client was waiting to receive a packet, it may wait indefinitely.
B
The TCP server application on S can listen on P after reboot.
C
If the client sends a packet after the server reboot, it will receive a RST segment.
D
If the client sends a packet after the server reboot, it will receive a FIN segment.
GATE CSE 2021 SET-1   Computer Network


There are 5 questions to complete.

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