Flow & Error Control PYQ QUIZ GATE CS

Consider a source computer(S) transmitting a file of size 10⁶ bits to a destination computer(D)over a network of two routers (R₁ and R₂) and three links(L₁, L₂, and L₃). L₁connects S to R₁; L₂ connects R₁ to R₂; and L₃ connects R₂ to D.Let each link be of length 100 km. Assume signals travel over each link at a speed of 10⁸ meters per second.Assume that the link bandwidth on each link is 1Mbps. Let the file be broken down into 1000 packets each of size 1000 bits. Find the total sum of transmission and propagation delays in transmitting the file from S to D?

Let G(x) be the generator polynomial used for CRC checking. What is the condition that should be satisfied by G(x) to detect odd number of bits in error?

Frames of 1000 bits are sent over a 10^6 bps duplex link between two hosts. The propagation time is 25ms. Frames are to be transmitted into this link to maximally pack them in transit (within the link). What is the minimum number of bits (i) that will be required to represent the sequence numbers distinctly? Assume that no time gap needs to be given between transmission of two frames.

The values of parameters for the Stop-and – Wait ARQ protocol are as given below.

Bit rate of the transmission channel = 1Mbps

Propagation delay from sender to receiver = 0.75 ms
 
Time to process a frame = 0.25ms
 
Number of bytes in the information frame = 1980
   
Number of bytes in the acknowledge frame = 20
 
Number of overhead bytes in the information frame = 20 

Assume that there are no transmission errors. Then the transmission efficiency ( expressed in percentage) of the Stop-and – Wait ARQ protocol for the above parameters is _________( correct to 2 decimal place) .

Note:

This questions appeared as Numerical Answer Type.

Consider a binary code that consists only four valid codewords as given below.


00000, 01011, 10101, 11110



Let minimum Hamming distance of code be p and maximum number of erroneous bits that can be corrected by the code be q. The value of p and q are:

A computer on a 10Mbps network is regulated by a token bucket. The token bucket is filled at a rate of 2Mbps. It is initially filled to capacity with 16Megabits. What is the maximum duration for which the computer can transmit at the full 10Mbps?

A link has a transmission speed of 10⁶ bits/sec. It uses data packets of size 1000 bytes each. Assume that the acknowledgment has negligible transmission delay, and that its propagation delay is the same as the data propagation delay. Also assume that the processing delays at nodes are negligible. The efficiency of the stop-and-wait protocol in this setup is exactly 25%. The value of the one-way propagation delay (in milliseconds) is ___________.

The maximum window size for data transmission using the selective reject protocol with n-bit frame sequence numbers is:

Consider a 128×10³ bits/second satellite communication link with one-way propagation delay of 150 milliseconds. Selective retransmission (repeat) protocol is used on this link to send data with a frame size of 1 kilobyte. Neglect the transmission time of acknowledgment. The minimum number of bits required for the sequence number field to achieve 100% utilization is ___________

A sender uses the Stop-and-Wait ARQ protocol for reliable transmission of frames. Frames are of size 1000 bytes and the transmission rate at the sender is 80 Kbps (1Kbps = 1000 bits/second). Size of an acknowledgement is 100 bytes and the transmission rate at the receiver is 8 Kbps. The one-way propagation delay is 100 milliseconds.

Assuming no frame is lost, the sender throughput is __________ bytes/second.