Backward n frame protocol sending window size
When n bits are used to number the frames, the size of the transmission window should be less than 2n - 1. If the size of the transmission window is larger than 2n - 1, the receiver will not be able to distinguish between the new frame and the old frame. For example, 8 different serial numbers can be made with 3 bits, and the maximum number of transmission windows should be 8, but in fact, setting the transmission window to 8 will make the protocol unable to work under certain circumstances. " Choose " was equally exciting. Everyone was welcome to read it!
Fallback n frame protocol sending window size
The size of the sending window of the fallback N-frame protocol is greater than 1, and multiple data packets can be sent consecutively. " Choose " was equally exciting. Everyone was welcome to read it!
Backward n frame protocol and selective repeat protocol
Go-back- N (GGN): - In the stop-and-wait protocol, the sender can only send one frame at a time, and the channel utilization rate is low. However, the backward N-frame protocol uses a sliding window method, and the sender maintains a set of sending windows, and can send multiple data frames at a time. The receiver uses the method of cumulative confirmation, and the sender moves the sending window forward after receiving the confirmation. When there was a problem (such as frame loss or long delay), the sender used the method of retreating N frames to re-transmit. The timer here was used to recover data frames or confirm the loss of frames, similar to the timer in the pause protocol. Choosing the Repeat protocol: - Different from the N-frame backward protocol, when the receiver receives an out-of-order frame, it will not discard all subsequent frames like the N-frame backward protocol. Instead, it will buffer the correctly received out-of-order frame. When the sender found that a frame was lost, it only retransmitted the lost frame, instead of retransmitting the subsequent N frames from the lost frame like the backward N frames protocol. This could avoid unnecessary data retransmissions and improve transmission efficiency, especially in a poor network environment with a high packet loss rate. Both of these two types of protocol were designed to deal with the loss of frames and the disorder of order during data transmission to improve the reliability and efficiency of data transmission. However, the specific ways in which they dealt with the problem were different. "Choose" was equally exciting. Everyone was welcome to read it!
Channel utilization of backward n-frame protocol
The N-frame Backoff (GGN) protocol allows the sender to send multiple data frames in succession to improve channel utilization. In the stop-and-wait protocol, the sender could only send one frame at a time, and the channel utilization rate was low. However, GGN adopted the sliding window method, and the sender maintained a set of sending windows, which could send multiple data frames at a time. The calculation of channel utilization is related to many factors, such as data transmission rate, one-way transmission delay, data frame length, etc. Suppose the data transmission rate is R (bit per second), the one-way transmission delay is T (s), and the data frame length is L (bit). In an ideal situation, the sender can continue to send data frames without considering errors and retransmissions during transmission. At this time, the channel utilization can be approximately expressed as: <U>=<frac{L}>{(2T +<frac{L}{R})R}>. In the GGN protocol, the larger the transmission window, the more data frames allowed to be transmitted, and the higher the channel utilization rate. However, the transmission window could not be infinitely large. When using n bits to code, the maximum transmission window is <<2> n>-<1>. However, if there was an error and the transmission needed to be repeated, the GGN protocol's transmission mechanism would affect the channel utilization. Since GGN uses a cumulative acknowledgment method, the sender will move the sending window forward after receiving the acknowledgment. If the sender does not receive the acknowledgment or receives a negative acknowledgment (NAC), it needs to retreat N frames and resend all the sent frames after the acknowledgment frame. When an error occurs, the frame that has been transmitted correctly will also be retransmitted, thus reducing the channel utilization to a certain extent. "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!
Channel utilization calculation of backward n frame protocol
1. ** sender's angle ** - Let the time to send a frame be <T_f>, the transmission delay be <T_p>, and the size of the sending window be <W>. - In the stop-and-wait protocol (transmit window <<W = 1>>), the channel utilization rate <U>=<frac>{T_f}{T_f +2T_p}>. - For the backward frame protocol (GGN), the sender can send a continuous number of frames. The total time it takes for the sender to send the W frames is W, and the total time from the start of the transmission to the time it receives the first acknowledgment frame (assuming it is received correctly) is W. - Therefore, the channel utilization rate is <U>=<frac>{WTf>}{WTf +2Tp>}. 2. ** Receiving angle ** - The receiver used the cumulative confirmation method. - Assuming that the sender sent a number of frames, the receiver will discard all the frames after the number of frames. - The sender needs to re-transmit all the frames starting from the <k> th frame, which will affect the channel utilization. In the ideal case (error-free transmission), the channel utilization rate is calculated as before. In the case of errors, the channel utilization rate will be reduced due to retransmissions. The specific degree of reduction depends on the frequency and location of errors. 3. ** Overall consideration ** - The channel utilization is also related to the number of digits in the frame number, because the transmit window size, W, has a maximum limit, W'leqslant2 ^n- 1. When W is close to this maximum value, the channel utilization rate can be improved without error, but it also increases the risk of frame number confusion (like the example of the 2-bit number mentioned earlier). Once the error is retransmitted, the channel utilization rate will be greatly affected. "Choose" was equally exciting. Everyone was welcome to read it!
arq protocol sending window maximum
In the ARQ protocol, the maximum transmission window is related to the type of the protocol. 1. ** Stop and Wait ARQ protocol **: After sending a frame, the sending station must wait for an acknowledgment signal. After receiving an acknowledgment signal, it will continue to send the next frame. There is no mention of the maximum value of the sending window size. 2. ** Repeat ARQ protocol **: It is a combination of sliding window technology and automatic repeat request technology. The maximum sending window is 2^(n - 1)(considering the possible loss of the ACK, it will be repeated after a time limit). 3. ** Continuous ARQ protocol (includes two types of protocol: - For the backward N-frame protocol, 1 <transmission window <= 2n- 1. - For the selective replay protocol, the transmit window is <= 2^(n - 1), and when the transmit window is the maximum, the receive window = transmit window = 2n - 1. "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 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!
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 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!