Low Latency Ethernet 10G MAC Intel® FPGA IP User Guide

ID 683426
Date 3/01/2022
Public
Document Table of Contents

4.4.7. Unidirectional Feature

The MAC TX implements the unidirectional feature as specified by clause 66 in the IEEE802.3 specification. This is an optional feature supported only in 10G operations. When you enable this feature, two output ports—unidirectional_en, unidirectional_remote_fault_dis— and two register fields—UniDir_En (Bit 0), UniDirRmtFault_Dis (Bit 1)— are accessible to control the TX XGMII interface.

Table 15.  Register Field and Link Status
Bit 0 Register Field Bit 1 Register Field Link Status TX XGMII Interface Behavior
Don't care Don't care No link fault Continue to allow normal packet transmission.
0 Don't care Local fault Immediately override the current content with remote fault sequence.
1 0 Local fault Continue to send packet if there is one. Otherwise, override the IPG/IDLE bytes with remote fault sequence.4
1 1 Local fault Continue to allow normal packet transmission (similar to no link fault).
0 Don't care Remote fault Immediately override the current content with IDLE control characters.
1 Don't care Remote fault Continue to allow normal packet transmission (similar to no link fault).
4 At least a full column of IDLE (four IDLE characters) must precede the remote fault sequence.

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