Low Latency 100-Gbps Ethernet IP Core User Guide

ID 683160
Date 4/15/2021
Public
Document Table of Contents

3.2.1.1. Preamble, Start, and SFD Insertion

In the TX datapath the MAC appends an eight-byte preamble that begins with a Start byte (0xFB) to the client frame. If you turn on Enable link fault generation, this MAC module also incorporates the functions of the reconciliation sublayer.

The source of the preamble depends on whether you turn on the preamble pass-through feature by turning on Enable preamble passthrough in the LL 100GbE parameter editor.

If the preamble pass-through feature is turned on, the client provides the eight-byte preamble (including Start byte) on the data bus. The client is responsible for providing the correct Start byte.