Flow Control

Flow Control is a feature used to manage data traffic between devices to prevent congestion and packet loss. It ensures that the sending device does not overwhelm the receiving device with more data than it can handle.

When to Enable Flow Control

Enable Flow Control when connecting network devices, such as routers or switches, that operate at different speeds. For example, if you have a 2.5Gbps switch linked to a 1Gbps switch, Flow Control ensures smooth data flow by preventing packet loss. The faster device will temporarily pause transmissions to avoid overwhelming the slower one.

When Not to Enable Flow Control

Avoid enabling Flow Control in scenarios when low latency is critical, like real-time VoIP applications or online gaming. It may introduce delays by halting transmissions, negatively impacting performance.

Considerations When Using Flow Control

Flow Control is negotiated between devices. Both ends of a network link must support and agree to enable Flow Control for it to function properly. During the negotiation process, the devices exchange pause frames to manage the traffic flow. If one device supports Flow Control but the other does not, it will not be utilized on that link.

How to Configure Flow Control

Flow Control is configured globally through the Global Switch Settings in the Settings > Networks section. If specific devices need to enable or disable Flow Control, navigate to the Devices section and uncheck the Global Switch Settings option in the device's side panel.

What is the Flow Control limitation on the USW-Flex-2.5G-8 and USW-Flex-2.5G-8-PoE?

The USW-Flex-2.5G-8 switches are divided into two port groups: ports 1–4 and ports 5–10. When Flow Control is enabled, devices must be connected to the same group in order to use it. It is recommended to connect devices using Flow Control to ports 5–8, as ports 9 and 10 are typically used as uplinks to the rest of the network.