Basic CS-Networks [TCS Placement]: Sample Questions 24 - 25 of 133

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Question 24

Networks
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Describe in Detail

Essay▾

What is piggy Backing?

Explanation

  • Piggybacking is used to improve the efficiency of the bidirectional protocols.
  • In this technique a frame carrying data from A to B also carries control information about arrived (or lost) frames from B, Similarly a frame carrying data from B to A can also carry control information about the arrived (or lost) frames from A.
  • When a data frame arrives, instead of immediately sending control fame, the receiver waits until the network layer passes it to the next packet. The acknowledgement is then attached to the outgoing data frame.
  • The acknowledgement gets a free ride on the next outgoing data frame.
  • Thus, it is the technique of temporarily delaying outgoing acknowledgement so they can be hooked onto the next outgoing data frame.
Given the Image is Define the Piggy Backing

Question 25

Networks
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Describe in Detail

Essay▾

What is silly window syndrome?

Explanation

  • Silly window syndrome can ruin TCP performance when data is based to the sending TCP entity in large blocks, but receiving side reads only 1 byte at a time.
  • Arises in poor implementations of the transmission control protocol (TCP) when receiver accepts a few bytes at a time but sender transmits data in small segments repeatedly.
  • Small packets, on the network lead to a significant reduction in network performance and indicate an overloaded server or a sending application that is limiting throughput
  • Silly window syndrome is avoided by:
    • Receiver not advertising small windows- larger window until the window size can be increased by either one maximum segment size or by of the remote host՚s current window size.
    • The sender not transmit data unless:
  • A packet is at least as large as the maximum segment size
  • A packet with data half of the remote host՚s window size may be sent
  • All of the output data may be sent and there is no unacknowledged data or the NAGLE algorithm is disabled
Silly Window Syndrome

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