Is choosing the replay protocol a cumulative confirmation? Why?
Choosing the repeat protocol is not a cumulative acknowledgment. Accumulated acknowledgement would lead to mass retransmissions, and the selective retransmissions protocol was designed to avoid this situation. He chose the replay protocol to set up a single acknowledgment. At the same time, he increased the receive window and designed the receive buffer to buffer the frames that arrived out of order. This way, he could only replay the wrong frames. " Choose " was equally exciting. Everyone was welcome to read it!
Is choosing to resend a cumulative confirmation?
Choosing to re-transmit was not a cumulative confirmation. In the selective repeat protocol, the receiver could no longer use cumulative acknowledgment, but had to confirm each correctly received data packet one by one. The purpose of this is to make the sender only re-transmit the packets with errors. Accumulated acknowledgement meant that the receiver could send back a acknowledgement packet that could acknowledge all packets up to a certain serial number, instead of sending acknowledgement packets for every serial number. For example, in the protocol, the sender sends multiple packets, and the receiver sends back a packet with a specific confirmation sequence number after successfully receiving some of the packets. The sender knows that the previous packets have been successfully sent and received, and if necessary, resends the packets starting from the confirmation sequence number. This mechanism was also applicable to other layers such as the link layer. " Choose " was equally exciting. Everyone was welcome to read it!
Sr-protocol replay
In the SSR (selective repeat) protocol, the sender and the receiver each maintained a window. The sender only re-transmitted unacknowledged packets, while the receiver could receive and acknowledge non-ordered packets. The sender will initiate a sending window of length N. Each position in the window corresponds to a data packet and has a unique sequence number. At the same time, send_base (the left boundary of the sending window, representing the earliest unconfirmed sequence number) and nextseqnums (representing the next available sequence number) are defined. When receiving data from the upper layer, the sender of the PR will check whether there are any available serial numbers in the current window. If there are, the data will be packaged and sent, and a logical timer will be started for each data packet. Otherwise, the data may be stored in the buffer or the upper layer may be notified to wait. Each packet had its own logical timer. After the timer expired, the sender only retransmitted the single packet that had expired and restarted its timer. For example, during the transmission process, if data packet No. 2 is lost during transmission, the receiver will receive the data packet as long as the sequence number falls within the receiving window and there is no error in the code. For example, if the receiver receives data packet No. 0 and data packet No. 1 and sends the confirmation packet of these two, the receiving window will slide forward. When receiving packet 3 (non-orderly reception), confirmation packet 3 will be sent, but the receiving window cannot slide forward (because the previous packet 2 has not arrived). After receiving the confirmation packets 0 and 1, the sender would slide forward to the corresponding position and continue to send other packets whose serial numbers fell into the sending window. If the re-transmission timer of the second packet is expired, the second packet will be re-transmitted. "Choose" was equally exciting. Everyone was welcome to read it!
Is the select replay protocol a sliding window protocol?
Yes, the selective replay protocol was based on the sliding window flow control technology. It was a sliding window protocol. " Choose " was equally exciting. Everyone was welcome to read it!
Choose which layer the replay protocol is on
The selective replay protocol was a transport layer protocol. It was a specific example of automatic repeat request (ARQ), which could be used for message unit transmission and confirmation. It was designed to deal with problems such as packet loss, wrong packet, and disorder during network transmission to ensure reliable data transmission. In this protocol, the sending process continuously sends a number of frames according to a window of a specified size, and the receiving process continues to receive and confirm frames after an error occurs. Different from the Fallback N-frame protocol (GGN), it sets up a single acknowledgment, increases the receiving window, and designs a receive buffer to buffer the frames that arrive out of order. This allows only the wrong frames to be retransmitted, thereby improving transmission performance. "Choose" was equally exciting. Everyone was welcome to read it!
Which layer is the chosen replay protocol?
The selective replay protocol belonged to the data link layer. The data link layer was responsible for providing reliable data frame transmission on the physical medium, converting the bit stream of the physical layer into frames, and adding the necessary control information to the frames. In the data link layer, there was a thought map of the selective repeat protocol, which indicated that the selective repeat protocol was in the data link layer. " Choose " was equally exciting. Everyone was welcome to read it!
Slipping window to select the replay protocol
The sliding window selective repeat (PR) protocol was a sliding window protocol. In this protocol, the sender continuously sends a number of frames according to a window of a specified size. Even if a frame is lost in the process of sending, it will continue to send. The receiver's receiving window size was greater than 1. When an out-of-order packet was received, if the sequence number was in the receiving window, it would be first stored in the buffer and delivered to the upper layer after all the missing packets were collected. It used a selective acknowledgment method and only retransmitted the packets with errors. The sending window could only move to the right after receiving the confirmation of the leftmost sequence number, and the receiving window could only move to the right after receiving the data packet of the leftmost sequence number. Compared with the N-frame Backward (GGN) protocol, the receiver could only receive frames one by one in sequence, and the out-of-order frames were directly discarded. The cumulative acknowledgment method was used, and the sender would move the sending window forward after receiving the acknowledgment. If there was a need to re-transmit, the sender would use the N-frame Backward method to re-transmit all the sent frames after the acknowledgment frame. The selective replay protocol solved the problem of network resource waste caused by the loss of out-of-order frames in the GGN protocol. "Choose" was equally exciting. Everyone was welcome to read it!
Choose the size of the window for the replay protocol.
For the selective replay protocol, the window size is <= 2^(m - 1). When n bits are used to number the frames, in order to prevent the old and new receive windows from overlapping after the receiver moves the window forward, the maximum size of the transmit window does not exceed the range of the sequence number, that is, WT <2n-1. When the transmit window takes the maximum value, it is found to be the same as the transmit window and 2n-1 (in most cases, the transmit window is equal to the receive window and 2n-1, because this is the most efficient). If the value of the transmit window is greater than 2n-1, it may cause the new and old receive windows to overlap. "Choose" was equally exciting. Everyone was welcome to read it!
Choose which layer to set the replay protocol on
The selection of the replay protocol was set at the transport layer. Transmission layer protocol such as the Transmission Control protocol (TCM) used a packet replay strategy to deal with problems in network transmission to ensure reliable data transmission. Choosing a replay protocol was a way to achieve reliable transmission. It used a specific mechanism to ensure that only the wrong frames were retransmitted during the data transmission process to improve transmission efficiency. These operations were within the scope of the transmission layer. "Choose" was equally exciting. Everyone was welcome to read it!
What is the window size for selecting the replay protocol?
For the selective replay protocol, the window size was <=2^(m - 1), and the transmit window could not be larger than the receive window. To maximize efficiency, in most cases, the transmit window was equal to the receive window and was equal to 2n - 1 (n was the number of bits used to number the frame). However, this value must not exceed half of the range of the serial number to avoid the overlap of the new and old receive windows at the receiver. "Choose" was equally exciting. Everyone was welcome to read it!
Choose the smallest sending window for the replay protocol.
The minimum sending window in the Repeat Transmission protocol (SSR) was set to 1. The selective repeat protocol was proposed to improve the fallback N-frame protocol. Under this protocol, the receive window size was greater than 1 so that the receiver would first receive the data packets that arrived out of order without error codes and whose sequence numbers fell within the receive window. When the transmit window was also greater than 1, the channel utilization could be improved, allowing the sender to continue sending subsequent frames without receiving the acknowledgment of certain frames, but the transmit window could be as small as 1. "Choose" was equally exciting. Everyone was welcome to read it!