Question

What is the correct time-ordered sequence of transitions following the initial S1 transition in the RDT 2.1 Protocol when the ACK is corrupted?

a) S1, x₁ (ACK corrupted), x₂, x₃, x₄, S₄, x₅, S₆
b) S1, R₁ (ACK corrupted), S₂, R₃, S₃, S₄, R₄, S₆
c) S1, x₁ (ACK corrupted), x₂, x₃, x₄, R₄, x₅, S₆
d) S1, R₁ (ACK corrupted), S₂, x₃, S₄, R₄, x₅, S₆

Answer 1

The correct time-ordered sequence is option c) S1, x₁ (ACK corrupted), x₂, x₃, x₄, R₄, x₅, S₆.

Step-by-step explanation:

The correct time-ordered sequence of transitions following the initial S1 transition in the RDT 2.1 Protocol when the ACK is corrupted is option c) S1, x₁ (ACK corrupted), x₂, x₃, x₄, R₄, x₅, S₆.

In the RDT 2.1 protocol, 'S' represents the sender and 'R' represents the receiver. When the ACK is corrupted, the sender assumes the ACK is lost and retransmits the last packet.

So, the correct sequence is as follows:

1. S1: Sender sends the packet.
2. x₁ (ACK corrupted): The ACK is corrupted, indicating that it is lost.
3. x₂: Sender retransmits the packet.
4. x₃: Sender retransmits the packet.
5. x₄: Sender retransmits the packet.
6. R₄: Receiver receives the packet.
7. x₅: Receiver sends the ACK.
8. S₆: Sender receives the ACK and proceeds to the next packet.