Flow control

Flow Control

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• Flow Control

  

   

  What is flow control?

  Flow control is a technique used to regulate data transfer between computers or other nodes in a network. Flow control ensures that the transmitting device does not send more data to the receiving device than it can handle. If a device receives more data than it can process or store in memory at any given time, the data is lost and needs to be retransmitted.

  The purpose of flow control is to throttle the amount of data transmitted to avoid overwhelming the receiver's resources. This is accomplished through a series of messages that the receiver transmits to the sender to acknowledge if frames have been received. The sender uses these messages to determine when to transmit more data. If the sender does not receive an acknowledgement (ACK), it concludes that there has been a problem with the transmission and retransmits the data.

  Flow control is implemented in different ways, depending on how the sender and receiver handle messages and track data frames. There are two basic approaches to flow control: stop and wait and sliding window. The stop-and-wait approach is the simplest to implement, but it is not as efficient as sliding window, which delivers better network performance and utilizes network resources more effectively.

  Stop-and-wait flow control

  In the stop-and-wait approach, the sender segments the data into frames and then transmits one frame at a time to the receiver, which responds to each frame with an ACK message. This process occurs through the following steps:

  1. The sender transmits a data frame to the receiver.
  2. The sender waits for the receiver to respond.
  3. Upon receiving the frame, the receiver transmits an ACK to the sender.
  4. Upon receiving the ACK, the sender sends the next frame to the receiver and waits for the next ACK. If the sender does not receive an ACK within a defined time limit, known as a timeout, the sender retransmits the same frame.
  5. The process continues until the sender has finished transmitting all the data to the receiver.

  
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