Take You to Understand the Flow Control Technology in the Data Center Network

Posted on Jun 25, 2023 by

Flow control technology is a basic function of Ethernet, designed to prevent frame loss in the case of port congestion. Broadly speaking, flow control technology can be divided into four-layer flow control and seven-layer flow control. Flow control technology is applied to each network protocol layer and serves different purposes. In this article, we'll delve into these different aspects to gain a comprehensive understanding of flow control techniques.

Flow Control Technology in Data Center Network

Traffic control has become an indispensable technology in data center networks, such as Priority-Based Flow Control (PFC). The scope and granularity of flow control enforcement varies across different network layers. Higher-level network layers can gain a more detailed understanding of the internals of traffic, allowing for more precise flow control. However, this level of control comes at the cost of increased hardware resource consumption. Flow control is mainly at three levels, here is an explanation for you.

Flow Control at the Physical Layer

At the physical layer, flow control technology focus on regulating the transmission of packets over physical connections. One of the common techniques used is the Ethernet flow control protocol, which allows a device to send pause frames to its connected devices, requesting a temporary cessation of data transmission. This mechanism is especially useful in situations where the receiving device cannot handle incoming traffic, preventing packet loss and congestion. By utilizing flow control at the physical layer, data center networks can maintain smooth and efficient data transmission.

Flow Control at the IP Layer

Flow control at the IP layer involves managing the flow of network-layer packets. Various mechanisms exist to control the rate at which packets are transmitted. One popular technique is the Explicit Congestion Notification (ECN), which allows routers to notify the sending device about congestion in the network. Upon receiving the notification, the sender can adjust its transmission rate accordingly, preventing network congestion and optimizing overall performance. IP layer flow control ensures efficient utilization of network resources and enhances the reliability of data transmission.

Intelligent Flow Control

Intelligent traffic control runs at the application layer and provides advanced traffic management capabilities. This type of flow control technology is tailored to the specific requirements of an application to optimize its performance. By analyzing application-level data and employing sophisticated algorithms, intelligent traffic control can prioritize critical traffic, efficiently allocate bandwidth resources, and alleviate bottlenecks. This level of traffic control requires specialized hardware devices and deep knowledge of application behavior. Intelligent traffic control is especially valuable in data center networks where multiple applications with different needs coexist.

What is Flow Control Technology on Switch?

In a networking environment, a network switch is an essential device that facilitates the switching of packets within a local area network (LAN). Flow control is a key function provided by switches to effectively manage data traffic. The flow control technology on the switch can solve the problem of the transmission rate mismatch between the sending device and the receiving device. One of the most commonly used protocol standards is IEEE 802.3x, which uses pause frames sent from receiving devices to temporarily stop data transmission.

By implementing flow control techniques on switches, network administrators can optimize network performance and ensure reliable data transmission. Flow control on the switch prevents packet loss, avoids congestion, and keeps traffic balanced, improving overall network efficiency. At present, there are many brands of Ethernet switches on the market equipped with flow control technology, especially PFC technology, which is very common. For example, FS data center switches support PFC technology, which can greatly improve data center performance and resource utilization.

Switches N5860-48SC N8560-48BC N8560-32C N8560-64C
Ports 48x 10G SFP+| 8x 100G QSFP28 48x 25G SFP28| 8x 100G QSFP28 32x 100G QSFP28 64x 100G QSFP28
Support MLAG/Stacking MLAG/Stacking MLAG/Stacking MLAG/Stacking


Flow control technology plays a vital role in the data center network, ensuring smooth and efficient data transmission. It operates at different network layers, providing different levels of control and granularity. Flow control at the physical layer regulates the transmission of data over physical connections, while flow control at the IP layer manages the flow of packets at the network layer. Application-layer intelligent traffic control optimizes performance by prioritizing critical traffic and efficiently allocating bandwidth resources. Through flow control technology, the data center network can ensure efficient and reliable data transmission, realize seamless communication, and improve the overall user experience in the digital age.

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