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Ixiasoft
4.1.1.1. Transmit Path Blocks
The Interlaken IP core transmit data path has the following four main functional blocks:
- TX MAC
- TX PCS
- TX PMA
TX Transmit Buffer
The Interlaken IP core TX transmit buffer aligns the incoming user application data, itx_din_words in the IP core internal format.
TX MAC
The Interlaken IP core TX MAC performs the following functions:
- Inserts burst and idle control words in the incoming data stream. Burst delineation allows packet interleaving in the Interlaken protocol.
- Performs flow adaption of the data stream, repacking the data to ensure the maximum number of words is available on each valid clock cycle.
- Calculates and inserts CRC24 bits in all burst and idle words.
- Inserts calendar data in all burst and idle words, if you configure in-band flow control.
- Stripes the data across the PCS lanes. Configurable order, default is MSB of the data goes to lane 0.
TX PCS
The FPGA soft logic implements TX PCS. In PAM4 mode, the IP core contain a soft logic transcoder block to work with RS FEC (544, 514) of the TX PMA. The Interlaken IP core TX PCS block performs the following functions for each lane:
- Inserts the meta frame words in the incoming data stream.
- Calculates and inserts the CRC32 bits in the meta frame diagnostic words.
- Scrambles the data according to the scrambler seed and the protocol-specified polynomial.
- Performs 64B/67B encoding.