Triple-Speed Ethernet Intel® FPGA IP User Guide

ID 683402
Date 11/25/2022
Public

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4.1.4.1. Preamble Processing

The MAC function uses the SFD (0xD5) to identify the last byte of the preamble. If an SFD is not found after the seventh byte, the MAC function rejects the frame and discards it.

The IEEE standard specifies that frames must be separated by an interpacket gap (IPG) of at least 96 bit times. The MAC function, however, can accept frames with an IPG of less than 96 bit times; at least 8-bytes and 6-bytes in RGMII/GMII (1000 Mbps operation) and RGMII/MII (10/100 Mbps operation) respectively.

The MAC function removes the preamble and SFD fields from valid frames.