Low Latency 40G for ASIC Proto Ethernet Intel® FPGA IP User Guide

ID 683221
Date 11/10/2022
Document Table of Contents Length/Type Field Processing

This two-byte header represents either the length of the payload or the type of MAC frame.
  • Length/type >= 0x600—The field represents the frame type. The following frame types are possible:
    • Length/type = 0x8100—VLAN or stacked VLAN tagged frames. The MAC RX continues to check the frame and payload lengths.
    • Length/type = 0x8808—Control frames. The next two bytes are the Opcode field that indicates the type of control frame. For pause frames (Opcode = 0x0001) and PFC frames (Opcode = 0x0101), the MAC RX proceeds with pause frame processing.
    • For other field values, the MAC RX forwards the receive frame to the client.