40- and 100-Gbps Ethernet MAC and PHY MegaCore Function User Guide
3.2.9. Pause Control and Generation Interface
The pause control interface implements flow control as specified by the IEEE 802.3ba 2010 100G Ethernet Standard.The pause logic, upon receiving a pause packet, temporarily stops packet transmission, and can pass the pause packets through as normal traffic or drop the pause control frames in the RX direction.
Signal Name |
Direction |
Description |
---|---|---|
pause_insert_tx |
Input |
Edge triggered signal which directs the IP core to insert a pause frame on the Ethernet link. |
pause_insert_time [15:0] |
Input |
Specifies the duration of the pause in pause quanta. The pause control settings in the pause registers determine the duration of the pause quanta (pause quanta is equal to 512-bit time). |
pause_insert_mcast |
Input |
When asserted, specifies that the IP core should generate a pause packet with the well‑known multicast address of 01-80-C2-00-00-01. If deasserted, the pause is generated with the specified MAC address (pause_insert_dst), which is typically a unicast address. |
pause_insert_dst [47:0] |
Input |
Specifies the MAC address for a unicast pause. |
pause_insert_src [47:0] |
Input |
Specifies source address of the pause packet. |
pause_match_from_rx | Output |
Asserted to indicate an RX pause signal match. Used only when RX configurations are instantiated. The IP core asserts this signal when it receives a pause request with an address match, to signal the TX MAC to throttle its transmissions on the Ethernet link. |
pause_time_from_rx[15:0] | Output |
Asserted for RX pause time. Used only when RX configurations are instantiated. |
pause_match_to_tx | Input |
Asserted to indicate a TX pause signal match. Used only when TX configurations are instantiated. |
pause_time_to_tx[15:0] | Input |
Asserted for TX pause time. Used only when TX configurations are instantiated. |