Flow Control in Computer Networks

Flow control in computer networks is a mechanism used to regulate the flow of data between sender and receiver to ensure efficient and reliable communication. It manages the rate at which data is transmitted to prevent data overflow, congestion, and loss. Flow control mechanisms are essential in preventing the receiver from being overwhelmed by a faster sender, which can lead to packet loss or system congestion.

In the below PDF we discuss about Flow Control  in detail in simple language, Hope this will help in better understanding.

Importance of Flow Control:

In a computer network, devices communicate by exchanging data packets. Without proper flow control, these packets can collide, get lost, or overwhelm network resources, leading to delays, inefficiencies, and even network failures. Flow control helps prevent these issues by regulating the pace of data transmission, ensuring smooth and uninterrupted communication.

Techniques of Flow Control:

  1. Buffering: Buffering is a fundamental flow control technique that involves the use of temporary storage buffers at the sender and receiver ends to hold data during transmission. Buffers allow the sender to continue transmitting data at its maximum rate without overwhelming the receiver. The receiver retrieves data from the buffer at its own pace, allowing it to process data efficiently without data loss.
  2. Sliding Window Protocol: The sliding window protocol is a flow control mechanism used in packet-switched networks to optimize data transmission and minimize delays. It allows the sender to transmit multiple packets (window size) before waiting for acknowledgments from the receiver. The receiver acknowledges the successful receipt of packets and indicates the next expected packet sequence number. Sliding window protocols, such as Selective Repeat and Go-Back-N ARQ, are widely used for reliable data transmission in computer networks.
  3. Rate-Based Flow Control: Rate-based flow control regulates the transmission rate of data based on network conditions, available bandwidth, and receiver capacity. In rate-based flow control, the sender adjusts its transmission rate dynamically to match the receiving capacity of the receiver and prevent data overflow. Techniques such as congestion avoidance algorithms (e.g., TCP congestion control) and traffic shaping mechanisms are used to control data flow rates in computer networks.
  4. Window Size Adjustment: Flow control mechanisms often involve adjusting the size of the transmission window based on network conditions and feedback from the receiver. The sender dynamically adjusts the window size to optimize data transmission and avoid congestion. Adaptive algorithms, such as TCP’s congestion control algorithms (e.g., TCP Reno, TCP Cubic), continuously monitor network conditions and adjust the transmission window size accordingly to maximize throughput and minimize packet loss.
  5. Explicit Flow Control Signals: Some flow control mechanisms use explicit signals or messages exchanged between the sender and receiver to regulate data flow. For example, in protocols like XON/XOFF or Request-to-Send/Clear-to-Send (RTS/CTS), the receiver sends control signals to the sender to indicate its readiness to receive data or pause transmission temporarily to prevent data overflow. These explicit flow control signals help synchronize data transmission between sender and receiver and prevent data loss or congestion.


Flow control plays a crucial role in maintaining the efficiency and reliability of computer networks. By regulating the flow of data packets, it prevents congestion, reduces delays, and ensures smooth communication between devices. Understanding flow control mechanisms is essential for network administrators, engineers, and anyone involved in designing or managing computer networks. As technology continues to evolve, the importance of efficient flow control mechanisms will only grow, ensuring the seamless operation of our interconnected world.

Related Question

Flow control is a mechanism used to manage the flow of data between devices in a computer network to ensure that the sender does not overwhelm the receiver with data it cannot process.

Flow control is important to prevent congestion, buffer overflow, and packet loss, which can degrade network performance and reliability.

Errors in computer networks can be categorized into three main types: single-bit errors, burst errors, and packet loss. Single-bit errors involve the alteration of one bit in a data unit, burst errors involve multiple contiguous bits being corrupted, and packet loss occurs when entire packets of data fail to reach their destination.

Error detection is typically achieved using techniques such as checksums, cyclic redundancy checks (CRC), and parity bits. These methods involve adding additional bits to the transmitted data, which are then used to verify the integrity of the data at the receiver’s end.

Error correction techniques allow the receiver to not only detect errors but also correct them, thus ensuring the accuracy of the transmitted data. Examples of error correction techniques include automatic repeat request (ARQ) protocols and forward error correction (FEC) codes.


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