F-Tile Ethernet Intel® FPGA Hard IP User Guide

ID 683023
Date 10/02/2023
Public

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7.2.2. TX MAC Avalon ST Client Interface with Enabled Preamble Passthrough

When you turn on Preamble Passthrough in the parameter editor, you must provide 8 preamble bytes to the TX MAC interface.
The table below describes TX MAC field positions with enabled Preamble Passthrough parameter.
  • MII Start of Packet control byte always replaces the first preamble byte.
  • Bits[55:8] are the preamble bits, typically set to the 0x55 value.
  • Bits[7:0] is the last preamble byte. In a standard preamble, it is set to the Start Frame Delimeter 0xD5 value.
Table 37.  TX MAC Field Positions in i_tx_data with Preamble Passthrough Enabled for 10GE/25GE/100GE Ports
Attention:

10GE/25GE requires multiple transfer cycle for header data.

The (') symbol in the 10GE/25GE i_tx_data column represents transfer on the subsequent cycle.

The ('') symbol in the 10GE/25GE i_tx_data column represents transfer on the 2nd subsequent cycle.

100GE

i_tx_data

10GE/25GE

i_tx_data

MAC Field Note
[511:504] [63:56]'' Custom Preamble [63:56] MII SOP control channel replaces it.
[503:496] [55:48]'' Custom Preamble [55:48] 0x55
[495:488] [47:40]'' Custom Preamble [47:40] 0x55
[495:480] [39:32]'' Custom Preamble [39:32] 0x55
[479:472] [31:24]'' Custom Preamble [31:24] 0x55
[471:464] [23:16]'' Custom Preamble [23:16] 0x55
[463:456] [15:8]'' Custom Preamble [15:8] 0x55
[455:448] [7:0]'' Custom Preamble [7:0] 0xD5 (SFD)
[447:440] [63:56]' Dest Addr[47:40]  
[439:432] [55:48]' Dest Addr[39:32]  
[431:424] [47:40]' Dest Addr[31:24]  
[423:416] [39:32]' Dest Addr[23:16]  
[415:408] [31:24]' Dest Addr[15:8]  
[407:400] [23:16]' Dest Addr[7:0]  
[399:392] [15:8]' Src Addr[47:40] When you turn on Source Address Insertion, contents are replaced by txmac_saddr unless i_tx_skip_crc is high.
[391:384] [7:0]' Src Addr[39:32]
[383:376] [63:56] Src Addr[31:24]
[375:368] [55:48] Src Addr[23:16]
[367:360] [47:40] Src Addr[15:8]
[359:352] [39:32] Src Addr[7:0]
[351:344] [31:24] Length/Type[15:8]
[343:336] [23:16] Length/Type[7:0]
[335:0] [15:0]
Table 38.  TX MAC Field Positions in i_tx_data with Preamble Passthrough Enabled for 40GE/50GE Ports
40GE/50GE

i_tx_preamble/i_tx_data

MAC Field Note
TX Preamble [63:56] Custom Preamble [63:56] MII SOP control channel replaces it.
TX Preamble [55:48] Custom Preamble [55:48] 0x55
TX Preamble [47:40] Custom Preamble [47:40] 0x55
TX Preamble [39:32] Custom Preamble [39:32] 0x55
TX Preamble [31:24] Custom Preamble [31:24] 0x55
TX Preamble [23:16] Custom Preamble [23:16] 0x55
TX Preamble [15:8] Custom Preamble [15:8] 0x55
TX Preamble [7:0] Custom Preamble [7:0] 0xD5 (SFD)
TX Data[127:120] MAC Dest Addr[47:40]  
TX Data [119:112] MAC Dest Addr[39:32]  
TX Data [111:104] MAC Dest Addr[31:24]  
TX Data [103:96] MAC Dest Addr[23:16]  
TX Data[95:88] MAC Dest Addr[15:8]  
TX Data [87:80] MAC Dest Addr[7:0]  
TX Data [79:72] MAC Src Addr[47:40] When you turn on Source Address Insertion, contents are replaced by txmac_saddr unless i_tx_skip_crc is high.
TX Data [71:64] MAC Src Addr[39:32]
TX Data [63:56] MAC Src Addr[31:24]
TX Data [55:48] MAC Src Addr[23:16]
TX Data [47:40] MAC Src Addr[15:8]
TX Data [39:32] MAC Src Addr[7:0]
TX Data [31:24] Length/Type[15:8]
TX Data [23:16] Length/Type[7:0]
TX Data [15:0] MAC Client data or VLAN header