F-Tile Ethernet Intel® FPGA Hard IP User Guide

ID 683023
Date 10/04/2021

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7.4.1. TX MAC Segmented Client Interface with Disabled Preamble Passthrough

Figure 35. Fields and Frame Boundaries in an Ethernet PacketWhen you turn off Preamble Passthrough in the parameter editor, i_tx_mac_data must be written as shown below for the first cycle of data presented to the MAC.
Note: For 10GE/25GE channels, multiple cycles are required to write the header data.
Table 39.  TX MAC Field Positions in i_tx_mac_data with Preamble Passthrough Disabled

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

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





MAC Field Note
[7:0] [7:0]' Dest Addr[47:40] The first octet of the Destination Address, follows Start Frame Delimiter (SFD).
[15:8] [15:8]' Dest Addr[39:32]
[23:16] [23:16]' Dest Addr[31:24]  
[31:24] [31:24]' Dest Addr[23:16]  
[39:32] [39:32]' Dest Addr[15:8]  
[47:40] [47:40]' Dest Addr[7:0]  
[55:48] [55:48]' Src Addr[47:40] When you turn on Source Address Insertion, contents are replaced by txmac_saddr unless i_tx_mac_skip_crc is high.
[63:56] [63:56]' Src Addr[39:32]
[71:64] [7:0] Src Addr[31:24]
[79:72] [15:8] Src Addr[23:16]
[87:80] [23:16] Src Addr[15:8]
[95:88] [31:24] Src Addr[7:0]
[103:96] [39:32] Length/Type[15:8]
[111:104] [47:40] Length/Type[7:0]
[…:112] [63:48]
  • In the table above, the byte order on the bus flows from LSB to MSB, the first byte of the MAC destination address is the LSB. The MAC considers this to be the first byte after the Start Frame Delimiter (SFD).
  • The bit numbered 0 is always the LSB of each byte.
    • For example, on 40GE/50GE/100GE/200GE/400GE interface, i_tx_data[0] transmits after the SFD, and corresponds to the Ethernet destination address unicast/multicast bit.