Link Level Flow Control

Link level flow control (LLFC) is a way to alleviate system congestion by pausing data transmission.

When a receiving device is congested, it communicates with the transmitting device by sending a PAUSE frame that instructs the device to stop data transmission for a specific time. This feature is available for each port in all front ports and applies to all traffic on the link. Extreme supports the generation (Tx) and reception (Rx) of PAUSE frames for each physical interface or port channel.

By default, LLFC reception is enabled.

Refer to Configuring link level flow control for the steps to configure LLFC.

Note

Pause and PFC LLFC are supported only on devices based on the XGS chipset family. For more information, see Supported Hardware.

As a best practice, stop the traffic on the interface before you configure LLFC on an interface or port channel.
A flow control configuration on an interface applies to all traffic received over the interface.
Flow control thresholds are tuned through default maximum queue sizes of ingress BD consumption.
A service policy cannot be applied to an interface if a flow control configuration exists. The reverse is also true.