40- and 100-Gbps Ethernet MAC and PHY MegaCore Function User Guide

ID 683114
Date 6/15/2022
Public
Document Table of Contents

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.

Table 24.  Pause Control and Generation SignalsDescribes the signals that implement pause control. You can also access the pause functionality using the pause registers for any variant of the 40-100GbE IP core.

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.