Low Latency 40- and 100-Gbps Ethernet MAC and PHY MegaCore Function User Guide

ID 683628
Date 12/28/2017
Public
Document Table of Contents
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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 Low Latency 40-100GbE 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 .