Question

What is the major disadvantage of RDT 3.0? Please discuss how this major disadvantage can be rectified.

Answer 1

RDT is Reliable Data Transfer which provides support in transferring packets without any disconnection in transmission. It ensures that the packets sent from source is delivered to destination.

This reliable data transfer protocol is called stop and wait protocol because for every packet sent, the sender will stop and wait for the acknowledgement from the receiver that the packet has been received.

The major drawback of Reliable Data Transfer 3.0 will be Channels with Error and Loss and how to detect the loss of packet and what to do when this error occurs. When packet loss occurs it can be detected by some techniques like ACK, Check summing, Sequence numbers and re-transmissions.

The sender will wait until the acknowledge is received from the receiver end as the sender does not know whether data packet has lost or ACK is lost and at certain time of waiting the sender will re-transmit the packets.

In all the cases, if the sender doesn't know whether data has lost or ack has not received and becomes delaying, then data packets can be re-transmitted. For re-transmission time is important which can be monitored by Countdown Timer, this will be needed when packets are first sent or packets or re-transmitted and to respond to a timer- interrupt.

Packets with no loss operation:

Sender Receiver Send pckto pekto ACKO rov pekto, Send ACKO rov ACKO * send pckt1pckt1 rev pekti ACKI send A CK1 rov ACK1 send pckto pekto rev pekto send ACKO AEKO