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What is the advantage of selective repeat over go back n?
Go back N and Selective Repeat gives better efficiency than Stop and Wait ARQ. Buffer requirement in Selective Repeat is very large. If the system does not have lots of memory, then it is better to choose Go back N. Selective Repeat requires large number of bits in sequence number field.
What is the use of selective repeat protocol?
An alternative strategy, the selective repeat protocol, is to allow the receiver to accept and buffer the frames following a damaged or lost one. Selective Repeat attempts to retransmit only those packets that are actually lost (due to errors) : Receiver must be able to accept packets out of order.
Where is stop and wait protocol used?
It is used in Connection-oriented communication. It offers error and flows control. It can be used in data Link and transport Layers. Stop and Wait ARQ executes Sliding Window Protocol with Window Size 1.
For what kind of network stop and wait ARQ and go back N ARQ used?
Comparison Table-
| Stop and Wait ARQ | Go back N | |
|---|---|---|
| CPU usage | Low | Moderate |
| Level of difficulty in Implementation | Low | Moderate |
| Acknowledgements | Uses independent acknowledgement for each packet | Uses cumulative acknowledgements (but may use independent acknowledgements as well) |
| Type of Transmission | Half duplex | Full duplex |
Does TCP use selective repeat or Go-Back-N?
TCP is different from selective repeat because SR requires individual acknowledgement of each packet that was sent by the receiver; but rather than selectively ACKing every packet, TCP sends an ACK for the next packet that it is expecting (like GBN) and buffers the ones that it has received so far, even if they’re out …
Why Go-Back-N ARQ is not as efficient as selective repeat ARQ?
In Go-Back-N receiver discards all the frames after the damaged frame hence, it doesn’t need to store any frames. Selective repeat protocol does not discard the frames arrived after the damaged frame instead it stores those frames till the damaged frame arrives successfully and is sorted in a proper sequence.
Is selective reject and selective repeat same?
Summary. Selective Repeat is part of the automatic repeat request (ARQ). The receiver may selectively reject a single frame, which may be retransmitted alone; this contrasts with other forms of ARQ, which must send every frame from that point again. The receiver accepts out-of-order frames and buffers them.
What is main disadvantage of stop and wait protocol?
disadvantages of stop-and-wait: fairly slow: the sender can send at most one new packet per RTT. not robust: if the ack can get lost, when the receiver gets a packet, the receiver cannot tell if it is a retransmission or a new packet.
Does TCP use selective repeat or Go back N?
How are selective repeat and Go back N different?
The main difference between these two protocols is that after finding the suspect or damage in sent frames go-back-n protocol re-transmits all the frames whereas selective repeat protocol re-transmits only that frame which is damaged.
What is the downside of go back n and how it was resolved in selective repeat?
5. In Go-Back-N Protocol, neither sender nor at receiver need sorting. In selective Repeat protocol, receiver side needs sorting to sort the frames. In selective Repeat protocol, if Receives receives a corrupt packet, it immediately sends a negative acknowledgement and hence only the selective packet is retransmitted.
What’s the difference between Selective Repeat and stop and wait?
In Selective Repeat protocol, Acknowledgement type is individual. 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.
Which is the efficiency of Selective Repeat protocol?
The efficiency of selective repeat protocol is the same as of Go-Back-N ARQ protocol’s efficiency. With this we have covered the three fow control protocol of computer networks, namely, STOP & WAIT, STOP & WAIT ARQ, Go-Back-N ARQ protocol and the Selective Repeat Protocol.
What is the purpose of 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.
How does Selective Repeat Work in flow control?
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.