Network Technology Tutorials Notes (16) Traffic and error control

<title>WAN and access Network technology</title> WAN and access Network Technology 1. Flow and error control

Flow control is a kind of technology to coordinate the working pace of sending station and receiving stations, it is to avoid sending too fast, so that the receiving stations cannot process and lose data. Usually the receiving station is to maintain a certain size of the receive buffer. When the received data enters the buffer, the receiver has to do a simple processing before it can clear the buffer and begin to receive the next batch of data. If the data sent by the sending station is too fast, the buffer will send an overflow problem, which can result in the loss of data. The use of flow control mechanism, can avoid this situation.

• Stop and wait for the protocol: the sending station each send a frame, must wait for the receiving station sends the reply signal to receive, then sends the next frame. If the response signal has not been received, then the sending station will wait all the time. The flow of data between the sending station and the station is controlled by the station.
  

  
  
  
  
  
  

• It is precisely because the link utilization of the protocol is not high, so we have a sliding window protocol. The main idea of the sliding window protocol is to allow multiple frames to be sent continuously without waiting for an answer.
  

  
  
  
  

The stop-wait protocol and the sliding window are the means of flow control, then the error control

During the data transfer process, there may be transmission errors or some frames may contain the wrong bits. Such frames may be rejected after being verified by the receiver. Usually deal with the transmission error method: First, affirmative response, the receiving station after the verification found that no error issued a positive response signal, the transmitter after receiving a positive response signal to continue to send the following data; second, the negative response signal, The receiving station receives a frame after verifying that the point is sent back a negative response signal, this time the transmitter should resend the frame; third, the time-out resend, the transmitter sends a frame to start the timing, in a certain time not received any response signal of the frame, At this point, the frame is considered lost and sent again. The idea is to use error detection techniques to automatically re-send lost frames and error frame requests, and therefore also called ARQ.

• Stop waiting for ARQ
  Shilai, the ACK value will only be 0 or 1.
• Choose to re-send Arq

• Back N-Frame Arq
  

Network Technology Tutorials Notes (16) Traffic and error control