Computer Networks Lecture 8: Reliable Data Transfer
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Questions and Answers

What is the main goal of reliability in data transfer?

  • Maximizing data throughput
  • Ensuring no data loss or bit errors (correct)
  • Reducing sender and receiver states
  • Minimizing delay in data transfer

What is the function called for ensuring reliable data transfer?

  • Flow Control Protocol (FCP)
  • Reliable Data Transfer (rdt) (correct)
  • Finite State Machine (FSM)
  • Congestion Avoidance Algorithm (CAA)

How are sender and receiver sides of reliable data transfer protocol developed?

  • Using Finite State Machines (FSMs) (correct)
  • By minimizing the number of states
  • Through congestion control mechanisms
  • By increasing the data transfer speed

What is the role of finite state machines (FSM) in reliable data transfer?

<p>To specify sender and receiver states (D)</p> Signup and view all the answers

In reliable data transfer, what determines the next state of the sender and receiver?

<p>Next event or action taken on state transition (B)</p> Signup and view all the answers

What does reliable data transfer aim to achieve with regards to data loss and bit errors?

<p>Minimizing both data loss and bit errors (A)</p> Signup and view all the answers

What does rdt2.0 use to detect bit errors in the channel?

<p>Checksum (B)</p> Signup and view all the answers

What does the receiver explicitly tell the sender if the packet is received OK?

<p>ACK (D)</p> Signup and view all the answers

What does the receiver explicitly tell the sender if the packet had errors?

<p>NAK (D)</p> Signup and view all the answers

What does the sender do on receipt of a NAK?

<p>Retransmits the packet (C)</p> Signup and view all the answers

What feedback messages are used in rdt2.0 for error detection?

<p>ACK and NAK (D)</p> Signup and view all the answers

What happens if ACK/NAK is not received in rdt2.0?

<p>Possible duplicate handling (A)</p> Signup and view all the answers

What mechanism does rdt2.0 use to handle duplicates?

<p>Sender adds sequence number (A)</p> Signup and view all the answers

What does the receiver do if a duplicate packet is received in rdt2.0?

<p>(Doesn't deliver up) Discards the duplicate packet (C)</p> Signup and view all the answers

What does the sender do after sending one packet in rdt2.0?

<p>(Doesn't deliver up) Waits for retransmission (C)</p> Signup and view all the answers

What is used by rdt2.0 to detect if a packet was received without errors?

<p>Checksum. (D)</p> Signup and view all the answers

If ACK/NAK is not received at sender end in rdt2.0, what will happen?

<p>Automatic retransmission. (B)</p> Signup and view all the answers

How does rdt2.0 handle a scenario where ACK/NAK is not received at sender's end?

<p>Retransmits current pkt. (B)</p> Signup and view all the answers

What is the main objective of reliable data transfer?

<p>Avoiding data loss and bit errors (B)</p> Signup and view all the answers

In reliable data transfer, what determines the next state of the sender and receiver?

<p>Finite state machines (FSM) (C)</p> Signup and view all the answers

What is the function called for ensuring reliable data transfer?

<p>Reliable data transfer (rdt) (D)</p> Signup and view all the answers

What does the receiver explicitly tell the sender if the packet is received without errors?

<p>ACK (A)</p> Signup and view all the answers

What feedback messages are used in reliable data transfer for error detection?

<p>ACK/NAK (C)</p> Signup and view all the answers

What does rdt2.0 use to detect bit errors in the channel?

<p>Checksums (D)</p> Signup and view all the answers

What does rdt2.0 use to recover from errors in the channel?

<p>Both ACKs and NAKs (C)</p> Signup and view all the answers

What is the fatal flaw in rdt2.0 if ACK/NAK is not received?

<p>The sender retransmits current packet (D)</p> Signup and view all the answers

What is used in rdt2.0 to detect bit errors in the channel?

<p>Checksum (B)</p> Signup and view all the answers

What is the role of acknowledgements (ACKs) in rdt2.0?

<p>To explicitly tell the sender that the packet was received OK (A)</p> Signup and view all the answers

What feedback messages are used in rdt2.0 for error detection?

<p>Control messages (ACK,NAK) (B)</p> Signup and view all the answers

What additional mechanism does rdt2.0 have beyond rdt1.0 for error detection during conversation?

<p>Error detection feedback (C)</p> Signup and view all the answers

What does the receiver do if a duplicate packet is received in rdt2.0?

<p>Discard and not deliver up the duplicate packet (B)</p> Signup and view all the answers

What happens if the ACK/NAK is not received at the sender's end in rdt2.0?

<p>The sender retransmits current packet (C)</p> Signup and view all the answers

What is the function called for ensuring reliable data transfer?

<p>rdt_send(data) (D)</p> Signup and view all the answers

What is the main goal of reliability in data transfer?

<p>To ensure no bit errors or loss of packets in the channel (A)</p> Signup and view all the answers

What determines the next state of the sender and receiver in reliable data transfer?

<p>Control messages (ACK,NAK) (A)</p> Signup and view all the answers

What does the sender do after sending one packet in rdt2.0?

<p>Waits indefinitely for a response from the receiver (B)</p> Signup and view all the answers

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