Data overflow occurs when a device receives too much data before it can handle it. Flow control instructs the sender how much information should be transferred to the recipient. This allows the data to be processed at an effective rate and prevents data loss or retransmission. There are mainly three types of flow control. In the Stop and Wait protocol, the sender sends one frame and then waits for the receiver to acknowledge it. The Go-Back-N protocol’s receiver end will only accept the correct sequence, whereas Out-of-order deliveries can also be accepted at the receiving end of the Selective Repeat technique.
Introduction to Flow Control in Network
The management of data flow between computers, devices, or network nodes is known as flow control. This allows the data to be processed at an effective rate. Data overflow, which occurs when a device receives too much data before it can handle it, results in data loss or retransmission.
In order to prevent data loss, flow control instructs the sender how much information should be transferred to the recipient. The sender must wait for an acknowledgment via this protocol before transmitting any additional data.
To read more about flow control, check out our dedicated article here.
Types of Flow Control Protocols
There are three approaches to regulate the data flow:
- Stop and Wait Protocol
It is the most basic flow control technique. This method involves sending one frame at a time from the transmitter to the receiver. The transmitter will cease and wait for a response from the receiver. The sender’s waiting time is the period of time between sending a message and getting a reply, and the sender is at rest throughout this period. As long as the sender has data to send, it will send the next data packet to the receiver after getting an acknowledgment (ACK), and so on.
To read more about stop and wait, check out our dedicated article here.
- GoBackN
Go-Back-N ARQ
protocol is a variation of the Automatic Repeat Request (ARQ) protocol. InGoBackN
, to fill the window, the sender delivers N packets. The sender waits for a cumulative ACK before continuing to send packets after sending the entire window. Out-of-order packets are discarded at the receiver end, and only in-order packets are received. The full window would be sent again, just like in the event of a packet loss.
- Selective Repeat
Selective Repeat ARQ is a variation of the ARQ protocol that manages sequence numbers and retransmissions in reliable communications. Similar toGoBackN ARQ
, particular repetition enables the transmitter to send a predetermined number of frames without having to wait for individual ACK from the recipient. It uses two equally sized windows, one for storing frames that need to be delivered and the other for storing frames that have been received by the receiver. The Selective Repeat protocol permits it to send many frames depending on the availability of structures in the sending window, even if it doesn’t acknowledge any frames in the interval.
To know more, check out our dedicated article here.
Difference between Stop and Wait, GoBackN, and Selective Repeat
Stop and Wait | GoBackN | Selective Repeat |
---|---|---|
In the Stop and Wait protocol, the sender sends one frame and then waits for the receiver to acknowledge it. | Any frames that were sent after the frame that is believed to have been damaged or lost are resent. | Only the suspected damaged or lost frames are retransmitted. |
In the Stop and Wait protocol, the Sender window size is 1. | In the Go-Back-N protocol, the Sender window size is N. | The Selective Repeat approach has a Sender window size of N. |
In the Stop and Wait protocol, the receiver window size is 1. | In the Go-Back-N protocol, the receiver window size is 1. | The Selective Repeat approach has a receiver window size of N. |
No particular sequence needs to be followed at the receiver end of the Stop and Wait protocol. | The Go-Back-N protocol’s receiver end will only accept the correct sequence. | Out-of-order deliveries can also be accepted at the receiving end of the Selective Repeat technique. |
In the Stop and Wait protocol, the transmission type is Half duplex. | In the Go-Back-N protocol, the transmission type is full duplex. | In the Selective Repeat protocol, the transmission type is full duplex. |
Efficiency formula for the Stop and Wait protocol is 1/(1+2*a), where a is the ratio of propagation delay to transmission delay. | Efficiency formula for the Go-Back-N protocol is N/(1+2*a), where a is the proportion of propagation delay to transmission delay and N is the number of packets transmitted. | Efficiency formula for the Selective Repeat protocol is N/(1+2*a), where a is the ratio of propagation delay to transmission delay and N is the number of packets transmitted. |
Conclusion
- The management of data flow between computers, devices, or network nodes is known as flow control. This allows the data to be processed at an effective rate.
- Data overflow, which occurs when a device receives too much data before it can handle it, results in data loss, which is prevented by instructing the sender, how much information should be transferred to the recipient.
- There are three flow control approaches, namely
Stop and Wait
,GoBackN
, andSelective Repeat
. - Stop and Wait protocol involves sending one frame at a time from the transmitter to the receiver. GoBackN ARQ and Selective Repeat ARQ use repetition to manage sequence numbers and retransmissions in reliable communications.