MMT_FINAL04

What assumptions does rdt1.0 make about the underlying channel?

• The channel may lose packets but does not introduce bit errors.

• The channel introduces bit errors but no loss.

• The channel is perfectly reliable with no bit errors or packet loss.

• The channel is unreliable, with frequent bit errors and packet losses.

In rdt1.0, what is the primary function of the sender?

• To send data into the underlying reliable channel

• To compute and validate checksums for error detection

• To retransmit packets upon error detection

• To handle duplicate packets

How does the receiver process packets in rdt1.0?

• It simply reads data from the underlying reliable channel.

• It discards packets if they are corrupted.

• It computes a checksum to detect errors.

• It sends ACKs or NAKs to the sender.

What additional mechanism is introduced in rdt2.0 to detect bit errors?

• Timers

• Sequence numbers

• Encryption

• Checksums

What protocol action does the receiver take when it detects a corrupted packet in rdt2.0?

• Sends an ACK

• Sends a NAK

• Ignores the packet and waits for retransmission

• Requests the sender to resend the packet

What issue arises in rdt2.0 if an ACK or NAK is corrupted?

• The receiver retransmits the corrupted ACK/NAK.

• The sender doesn’t know whether the packet was received correctly.

• The sender ignores the corrupted ACK/NAK and stops communication.

• The receiver processes the packet as if it were valid.

Why does rdt2.0 implement a stop-and-wait protocol?

• To ensure only one packet is sent at a time, reducing the chances of errors.

• To allow the receiver time to process corrupted packets.

• To minimize the use of sequence numbers in the protocol.

• To enable the sender to wait for an ACK or NAK before sending the next packet.

Why are sequence numbers added to packets in rdt2.1?

• To track the total number of packets sent

• To distinguish between duplicate packets

• To reduce the size of packet headers

• To avoid the use of ACKs and NAKs

Why are only two sequence numbers (0 and 1) sufficient in rdt2.1?

• The protocol uses alternating packets for simplicity.

• Sequence numbers are ignored by the receiver.

• The protocol transmits only two packets at a time.

• It ensures the protocol remembers whether the last packet was acknowledged.

What does the sender in rdt2.1 do if it receives a corrupted ACK/NAK?

• Stops communication entirely

• Waits for a retransmission request

• Resends the current packet

• Assumes the packet was received correctly