Aborting a Transmission - 2.6 English

1G/10G/25G Switching Ethernet Subsystem Product Guide (PG292)

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2.6 English

The aborted transfer of a packet on the client interface is called an underrun. This can happen if a FIFO in the AXI Transmit client interface empties before a frame is completed.

This is indicated to the core in one of two ways:

  • An explicit error in which a frame transfer is aborted by asserting tx_axis_tuser High while tx_axis_tlast is High.
  • An implicit underrun, in which a frame transfer is aborted by deasserting tx_axis_tvalid without asserting tx_axis_tlast.

When either of the two scenarios occurs during a frame transmission, the core inserts error codes into the data stream to flag the current frame as an errored frame. It remains the responsibility of the client to re-queue the aborted frame for transmission, if necessary.