The High Speed Ethernet IP core user interface is called the AXI4-Stream. There are two versions used — regular AXI4-Stream and straddled AXI4-Stream. 50 Gb/s operation allows use of only straddled AXI4-Stream whereas 40 Gb/s operation provides an option of 256-bit regular AXI4-Stream in addition to the 128-bit straddled interface. See the appropriate section in this guide for a detailed description of each.