Low Latency E-Tile 40G Ethernet Intel® FPGA IP User Guide

ID 683486
Date 4/09/2024
Document Table of Contents IP Core Strict SFD Checking

The Low Latency E-Tile 40G Ethernet core RX MAC checks all incoming packets for a correct Start byte (0xFB). If you turn on Enable Strict SFD check in the Low Latency E-Tile 40G Ethernet parameter editor, you enable the RX MAC to check the incoming preamble and SFD for the following values:

  • SFD = 0xD5
  • Preamble = 0x555555555555

The RX MAC checks one or both of these values depending on the values in bits [4:3] of the RXMAC_CONTROL register at offset 0x50A.

Table 11.  Strict SFD Checking Configuration
Enable Strict SFD check 0x50A[4]: Preamble Check 0x50A[3]: SFD Check Fields Checked Behavior if Check Fails
Off Don't Care Don't Care Start byte IP core does not recognize a malformed Start byte as a Start byte
On 0 0 Start byte
0 1 Start byte and SFD IP Core drops the packet
1 0 Start byte and preamble
1 1 Start byte and preamble and SFD