In a selective-repeat protocol the receiver performs thefollowing actions in res

Question

In a selective-repeat protocol the receiver performs thefollowing actions in response to an event: 1) Event: Correct reception of a packet whose sequence numberfalls in the receiver’s window. Action: A selective ACK packet is returned to the sender (plus someother local actions). 2) Event: Correct reception of a packet whose sequence number falls into [rcvbase - N, rcv base - 1], i.e., among those of packets that the receiver has alreadyacknowledged. Action: An ACK packet is generated and returned to the sender. 3) Event: Any otherpacket is received. Action: Ignore the packet. Is the ACK generated in Step 2 needed? And if so, why? Justifyyour answer. In a selective-repeat protocol the receiver performs thefollowing actions in response to an event: 1) Event: Correct reception of a packet whose sequence numberfalls in the receiver’s window. Action: A selective ACK packet is returned to the sender (plus someother local actions). 2) Event: Correct reception of a packet whose sequence number falls into [rcvbase - N, rcv base - 1], i.e., among those of packets that the receiver has alreadyacknowledged. Action: An ACK packet is generated and returned to the sender. 3) Event: Any otherpacket is received. Action: Ignore the packet. Is the ACK generated in Step 2 needed? And if so, why? Justifyyour answer.

Explanation / Answer

Dear, Event: Correct reception of a packet whose sequence numberfalls into [rcv base - N, rcv base - 1], i.e., among those ofpackets that the receiver has already acknowledged. Action: An ACK packet is generated and returned to thesender.     In this case it must be ACK must begenerated, even though this is a packet that the receiver haspreviously acknowledged. Its important to the receiver acknowledgesalready received packets with certain sequence numbers. If the receiver not acknowledge the packet, the sender'swindow would never move forward!. The sender and receiver will not have an identical view ofwhat has been received correctly and what has not. Selective Repeat protocols, the sender and reciver windowswill not coincide. For relaiable data transfer protocol it must sendack. Action: An ACK packet is generated and returned to thesender.     In this case it must be ACK must begenerated, even though this is a packet that the receiver haspreviously acknowledged. Its important to the receiver acknowledgesalready received packets with certain sequence numbers. If the receiver not acknowledge the packet, the sender'swindow would never move forward!. The sender and receiver will not have an identical view ofwhat has been received correctly and what has not. Selective Repeat protocols, the sender and reciver windowswill not coincide. For relaiable data transfer protocol it must sendack.

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