What is Flow-Control in the network?

 

In a network, a sender sends data and a receiver receives the data. But suppose in a situation where the sender sends data at a higher speed than the receiver can receive in the process, then the data will be lost. Water management methods will help ensure this. A rate control system will ensure that senders only send data at a rate that the receiver can receive and process. So, let's start with the blog and learn more about flow control.
Rate control tells the sender how much money to send to the recipient so it doesn't get lost. This method forces the sender to wait for confirmation before sending the next data. There are two ways to control data flow:

Stop and Hold Protocol
Sliding window protocol
Stop and Hold Protocol
This is the simplest spray control method. In this case, the sender will send one frame at a time to the receiver. Until then, the sender will stop and wait for the receiver's acknowledgment. When the sender receives the confirmation, it will send another data packet to the receiver and wait for another confirmation and the process will continue. This can be understood from the diagram below.


Suppose the recipient did not accept the frame sent and it was lost. Therefore, the receiver will not send any acknowledgment because it did not receive any frames. Also, the sender will not send the next frame because it has to wait for the confirmation of the previous frame it sent. Therefore, a stop position can be created here. To avoid such a situation, there is time. The sender will wait a specified time for the confirmation and if the confirmation is not accepted, it will resend the frame.

There are two types of delays when sending these frames:

Transmission Delay: The time taken by the sender to send the bits of the medium over the wire is called the transmission delay. This is calculated by dividing the amount of data (D) that should be sent by the bandwidth (B) of the link.
Td=D/B
Propagation delay: The time it takes for the last bit of the frame to travel from one part to the other is called propagation delay. It is calculated by dividing the distance between the transmitter and the receiver by the speed of propagation of the wave.
Tp = d/s; where d = distance between transmitter and receiver, s = speed of wave propagation

The transmission time to send the data frame to the reception frame is the same because the distance and speed will be the same for both frames. Therefore, the total time required to send the rat is

Total time = Td (transmission delay) + Tp (transmission delay for data frame) + Tp (transmission delay for reception frame)
The sender is active only during time Td and during the remaining time 2Tp, the sender waits for the acknowledgment of the receiver.

Efficiency = Effective time / total time

η=Td/(Td+2Tp)
Advantages of the Stop and Wait Protocol
It is very easy to do. Advantages of the stop and wait method
We can only send one package at a time.
If the distance between the sender and the receiver is large, the propagation delay will be greater than the transmission delay. Therefore, the performance will be very low.
After each delivery, the sender will wait for confirmation and this time will increase the regular delivery time.