AXI4-Stream for Coupled MAC+PCS Mode - 2.4 English

Coupled MAC+PCS mode is often called standard Fixed Ethernet (FixedE) mode. When configured in this mode, the AXI4-Stream interface operates in non-channelized segmented mode that ensures high throughput over a range of traffic profiles. The interface is dynamically reconfigurable during runtime to support multiple modes of Ethernet operation. The DCMAC Subsystem AXI4-Stream interface supports up to a total of 600 Gb/s bandwidth. It can be configured as six independent 100 Gb/s AXI4-Stream interfaces. Alternatively, the portions of the AXI4-Stream interface can be ganged together to deliver individual AXI4-Stream interface rates of 200 Gb/s or 400 Gb/s, in addition to combinations of 100 Gb/s, 200 Gb/s and 400 Gb/s.

The AXI clock frequencies in the following table are required to meet bandwidth for a given Ethernet interface.

You can use a lower frequency AXI clock to ease timing closure in some device speed grades. To enable use of a reduced clock frequency, a special mode exists that doubles the width of each 100GE AXI4-Stream interface to 512 bits while reducing to three the number of distinct 100GE AXI4-Stream interfaces. This mode is entered using the control fields ctl_tx_axis_cfg and ctl_rx_axis_cfg of the GLOBAL_MODE register. In addition, the control fields ctl_tx_pcs_active_ports and ctl_rx_pcs_active_ports of the same register must be set appropriately.