
Chapter 7: Functional Description 7–17
Congestion and Flow Control
February 2014 Altera Corporation 10-Gbps Ethernet MAC MegaCore Function User Guide
If pause frame transmission is triggered when the MAC is generating a pause
frame, the MAC ignores the incoming request and completes the generation of the
pause frame. Upon completion, if the
avalon_st_pause_data
signal remains
asserted, the MAC generates a new pause frame and continues to do so until the
signal is deasserted.
1 Assert the
avalon_st_pause_data
signal for at least 1 TX clock cycle
(
tx_tx_clk
) for the MAC to generate the pause frame right after the current
transmitting packet.
■
tx_pauseframe_control
register—A host (software) can set this register to trigger
pause frames transmission. Setting
tx_pauseframe_control[1]
to 1 triggers the
transmission of XOFF pause frames; setting
tx_pauseframe_control[0]
to 1
triggers the transmission of XON pause frames. The register clears itself after the
request is executed.
You can configure the pause quanta in the
tx_pauseframe_quanta
register. The
MAC sets the pause quanta field in XOFF pause frames to this register value.
1 The
tx_pauseframe_control
register takes precedence over the
avalon_st_pause_data
signal.
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