The timing of a data frame transmission through the internal 32-bit client-side interface is shown in the following figure. The beginning of the data frame is shown by the presence of the Start character (the /S/ codegroup in lane 0 in the following figure) followed by data characters in lanes 1, 2, and 3.
When the frame is complete, it is completed by a Terminate character (the T in lane 1 in the following figure). The Terminate character can occur in any lane; the remaining lanes are padded by the XGMII idle characters.
The following figure shows a similar frame to that in the preceding figure, with the exception that this frame is propagating an error. The error code is denoted by the letter E, with the relevant control bits set.