Achronix Speedster22i 10G/40G/100G Ethernet Manuel d'utilisateur télécharger pdf (Page 42)

42 UG029, September 6, 2013

sys_clk

ff_rx_data[511:0]

ff_rx_sop[0]

ff_rx_eop[0]

ff_rx_mod[5:0]

ff_rx_err[0]

ff_rx_vlan[1:0]

ff_rx_err_stat[23:0]

ff_rx_dval[0]

ff_rx_rdy[0]

ff_rx_preamble_val

ff_rx_preamble[55:0]

Figure 18: FIFO Receive Interface – Frame Transfer with User Pause

Frame Status

When frame reception terminates, the MAC Core writes a status word in a dedicated internal

FIFO to report information and events to the user application per frame. The status is

available with each frame with the last word of the frame (ff_rx_eop asserted) and is

presented on the ff_rx_err_stat[23:0] data bus.

 Invalid length (frame too long/short)

 CRC-32 error

 Link error (code violation)

 FIFO overflow exception

 Sequence error (e.g. local or remote fault)

 Frame error character

 VLAN/Stacked VLAN frame indication

 Frame length/type field. This is a copy of the length/type field as it is found in the

frame. Note that for VLAN frames, the value immediately following the 4-octet

VLAN tag is copied here.

If any of the error conditions happened, in addition the ff_rx_err signal will be asserted

together with the frame's last word. Note that the receive status signals

ff_rx_err_stat[23:0] can only be mapped to any segment of FIFO group 0 (10G: SEG0-

3, 40G: SEG0, 100G: SEG0). The per segment status signals ff_rx_err and

ff_rx_vlan[1:0] provide information about error conditions as well as VLAN/Stacked

VLAN frame indications to the user application on a per segment basis.

The frame status word is defined in the table below.

1 2 ... 37 38 39 40 41 42 43 44 45 46 47 ... 107 108

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Achronix Speedster22i 10G/40G/100G Ethernet Manuel d'utilisateur Page 42