220.127.116.11. Control Frame Identification
The mechanisms to process flow control frames from the Ethernet link are specific to the flow control mode of the LL 40GbE IP core. Therefore, control frames that are inappropriate to the IP core mode, simply pass through the RX MAC to the RX client interface.
If you turn off flow control by setting Flow control mode to the value of No flow control in the LL 40GbE parameter editor, the IP core might nevertheless receive a flow control request on the Ethernet link. Similarly, if you set Flow control mode to Standard flow control, the IP core might nevertheless receive a priority-based flow control request on the Ethernet link, and if you set Flow control mode to Priority-based flow control, the IP core might nevertheless receive a standard flow control request.
The IP core provides a three-bit RX status flag that identifies the control frames that appear on the RX client interface. The flag is one-hot encoded to identify whether the control frame is a standard flow control frame, a priority-based flow control frame, or a different type of control frame. If the flag has the value of 3'b000, the current packet on the RX client interface is not a control frame. You can use this flag to identify control frames on the RX client interface that the client prefers to ignore.
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