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 the maximum window size for the replay protocol.
If n bits are used to number the frame, the maximum size of the transmission window of the selected replay protocol does not exceed half of the range of the sequence number, that is, WT <= 2^(n - 1). When the transmit window is the maximum, it is the same as the receive window. In most cases, the transmit window is equal to the receive window and is equal to 2^(n - 1), because the maximum efficiency can be achieved in this case. At the same time, in order to prevent the new receiving window from overlapping with the old receiving window after the receiving end moves the window forward, the size of the sending window should meet this limit. Otherwise, the new and old receiving windows may overlap. "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!
How to set the size of the window for selecting the replay protocol?
For the selective replay protocol, the window size <=2^(m - 1). Firstly, the sending window could not be larger than the receiving window, or else the receiving window might overflow. Secondly, the pipeline grouping of the sending window must be maximized, but it must be ensured that there was no ambiguity. Assuming that the maximum sequence number is 7, that is, 0, 1, 2, 3, 4, 5, 6, 7, and the size of the sending window is 5, when the sending window sends 0, 1, 2, 3, 4, assuming that the receiving window receives all of them, the receiving window will move forward 5 times, and the receiving window will expect to receive 5, 6, 7, 0, 1. If the sending window does not receive any ACK, the receiving window will think that the re-sent 0, 1, 2, 3, 4 are new packets. Because the sending window <= receiving window. To maximize the send window, send window = receive window. Assuming that the transmission window is m, the reception window is also m. When the sending window sends m packets, the receiving window moves forward m, and the receiving window is m + 1,m + 2,... 2m。To avoid ambiguity, 2m <= the maximum number of the sequence. "Choose" was equally exciting. Everyone was welcome to read it!
Choose the size of the reception window of the Retransmission protocol.
By default, the size of the receive window is equal to the size of the send window in the selective replay protocol (SSR), but no information about the specific size was found. In the example where the frame sequence number is represented by 3 bits, the principle that the sending window meets is that the size of the sending window is equal to the receiving window, but the specific size of the receiving window is not specified. "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!
sliding window protocol window size
There was no fixed window size in the sliding window protocol. It would be determined based on various factors such as the specific network conditions, the application scenario of the protocol, the size of the sending buffer, and the receiving ability of the receiver. It was mentioned in Flink's window architecture related content that, for example, the window size could be set to 5s (an example of a step size of 2s). This was only an example of a specific application (a windowing application under the Flink architecture). It could not represent the common window size settings of the sliding window protocol. The purpose of the sliding window protocol was to control the flow to avoid congestion. The window size was determined to ensure the reliable transmission of data and to increase the network throughout as much as possible. For example, in network data transmission, if the sending party has a strong sending ability and the receiving party has a limited receiving ability, the window size needs to be set reasonably according to the receiving party's receiving ability and other factors, so that the sending party can send multiple data packets at the same time without receiving an acknowledgment, without causing problems such as network congestion or data loss due to sending too many data packets exceeding the receiving party's ability. "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!
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 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!