If ( Corrupted ( f. 27. Wait_For_Event() //wait for arrival of frame RSeqNo = 0 // Initialise sequence number of expected frame Receiver Site Algorithm of Selective Repeat Protocol Begin protocols should be mentioned shortly here. Resend frame if acknowledgement haven’t been received repeat protocol, an additional buffer at the receiver side is. Remove frames from sending window with positive ACK ![]() If ( NAK_No > SeqFirst & NAK_No < SeqN ) then The maximum size of the sending and receiving window is the same in this protocol, i.e., 2 m-1. Resend frame whose sequence number is with ACK Selective Repeat ARQ Like Go-back N, in the Selective Repeat Automatic Repeat Request protocol, the sender can transmit several packets before receiving the acknowledgements. Wait_For_Event() //wait for availability of packet SeqN = 0 // Sequence number of Nth frame window SeqFirst = 0 // Sequence number of first frame in window S_window = power(2,m-1) //Assign maximum window size Sender Site Algorithm of Selective Repeat Protocol begin It then continues sending the other frames. You can use any code editor you want to run this program. In this article, you would learn to code the Selective Repeat Protocol using C++. It is used to transmit data over noisy channels. Once, it has sent all the frames in the window, it retransmits the frame whose sequence number is given by the acknowledgements. Selective Repeat Protocol is a sliding window protocol used in the data link layer for efficient data transmission in computer networks. The selective Repeat protocol is the more efficient as it does not waste network resources on the data frames that the sender correctly transmits to the receiver node. Im writing an app in C that uses WinSockets to transfer data from sender app to receiver app and Im replacing stop-and-wait algorithm with selective repeat, where I now got stuck. The sender continues to send frames that are in its sending window. ![]() ![]() It sends the sequence number of the missing frame along with every acknowledgement frame. It then fills the receiving window with the subsequent frames that it has received. The receiver records the sequence number of the earliest incorrect or un-received frame. The maximum number of frames that can be sent depends upon the size of the sending window. Selective Repeat protocol provides for sending multiple frames depending upon the availability of frames in the sending window, even if it does not receive acknowledgement for any frame in the interim. For example, if the sequence number is from 0 – 15, the window size will be 8. The size is half the maximum sequence number of the frame. It uses two windows of equal size: a sending window that stores the frames to be sent and a receiving window that stores the frames received by the receiver. Here, only the erroneous or lost frames are retransmitted, while the good frames are received and buffered. Selective repeat protocol, also called Selective Repeat ARQ (Automatic Repeat reQuest), is a data link layer protocol that uses a sliding window method for reliable delivery of data frames.
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