Difference between Stop and Wait, GoBackN and Selective Repeat protocols
Stop and Wait protocol
Stop and Wait protocol is a protocol for flow control mechanism. In this protocol, sender sends one frame at a time and waits for acknowledgment from the receiver. Once acknowledged, sender sends another frame to the receiver. If acknowledgment is not received then frame/packet is retransmitted.
GoBackN protocol
GoBackN is also a protocol for flow control mechanism. In this protocol, sender sends n frames at a time and wait for commulative acknowledgment. If acknowledgment is not received then entire frames are retransmitted again.
Selective Repeat protocol
Selective Repeat is also a protocol for flow control mechanism. In this protocol, sender sends n frames at a time and wait for acknowledgment of packets received in particular order. If acknowledgment is not received then lost packets are transmitted again which is based on receiver acknowledgment. Receiver maintains a buffer of lost packets.
Following are some of the important differences between Stop and Wait protocol and Sliding Window protocol.
| Sr. No. | Key | Stop and Wait protocol | GoBackN protocol | Selective Repeat protocol |
|---|
| 1 | Sender window size | In Stop and Wait protocol, Sender window size is 1. | In GoBackN protocol, Sender window size is N. | In Selective Repeat protocol, Sender window size is N. |
| 2 | Receiver Window size | In Stop and Wait protocol, Receiver window size is 1. | In GoBackN protocol, Receiver window size is 1. | In Selective Repeat protocol, Receiver window size is N. |
| 3 | Minimum Sequence Number | In Stop and Wait protocol, Minimum Sequence Number is 2. | In GoBackN protocol, Minimum Sequence Number is N+1 where N is number of packets sent. | In Selective Repeat protocol, Minimum Sequence Number is 2N where N is number of packets sent. |
| 4 | Efficiency | In Stop and Wait protocol, Efficiency formular is 1/(1+2*a) where a is ratio of propagation delay vs transmission delay. | In GoBackN protocol, Efficiency formular is N/(1+2*a) where a is ratio of propagation delay vs transmission delay and N is number of packets sent. | In Selective Repeat protocol, Efficiency formular is N/(1+2*a) where a is ratio of propagation delay vs transmission delay and N is number of packets sent. |
| 5 | Acknowledgement Type | In Stop and Wait protocol, Acknowledgement type is individual. | In GoBackN protocol, Acknowledgement type is cumulative. | In Selective Repeat protocol, Acknowledgement type is individual. |
| 6 | Supported Order | In Stop and Wait protocol, no specific order is needed at receiver end. | In GoBackN protocol, in-order delivery only are accepted at receiver end. | In Selective Repeat protocol, out-of-order deliveries also can be accepted at receiver end. |
| 7 | Retransmissions | In Stop and Wait protocol, in case of packet drop,number of retransmition is 1. | In GoBackN protocol, in case of packet drop,numbers of retransmitions are N. | In Selective Repeat protocol, in case of packet drop,number of retransmition is 1. |
Published on 15-Apr-2020 10:39:00
