Visible to Intel only — GUID: lld1716935995202
Ixiasoft
Visible to Intel only — GUID: lld1716935995202
Ixiasoft
4.4.3.1. Connect the TX MAC Flow Control Interface
Use the i_tx_pause and i_tx_pfc input ports to send XOFF frames to the link partner. Follow the details described in the table and figure below:
Signal Name | Width | Description |
---|---|---|
i_tx_pause | 1 bit |
Assert this input to send a PAUSE XOFF frame on the Ethernet link.
Note: For 10GE/25GE channels, you should hold the i_tx_pause signal more than 205ns to get the request captured by the MAC.
|
i_tx_pfc[7:0] | 8 bits | Assert the bits to send a PFC XOFF frame on the Ethernet link for the corresponding priority queue.
Note: For 10GE/25GE channels, you should hold the i_tx_pfc signal more than 205 ns to get the request captured by the MAC.
You must maintain this input asserted until you want the IP core to end the pause period. Refer to the following figure for an example. This signal is functional only if priority flow control is enabled. |
The i_tx_pause and i_tx_pfc[7:0] ports are used to request the TX MAC transmit PAUSE and Priority Flow Control packets to the remote link partner.
- i_tx_pause requests PAUSE frames
- i_tx_pfc[n] requests PFC frames for queue n, [where n=0 to 7], respectively.
The timing diagram shows that an XOFF frame is transmitted when a packet in-flight is completed and the i_tx_pause input is asserted. When the XOFF frame is transmitted, the ipcore starts a holdoff counter. When the holdoff counter reaches zero, if the i_tx_pause is asserted, a new XOFF frame is transmitted. This sequence continues until the i_tx_pause is removed, at which point XON frame is transmitted.