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

ID 683426
Date 11/17/2023
Public

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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, 1G/10G, and 1G/2.5G/10G core variants. 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.