Retransmission Feature - 2.4 English - PG169

The retransmission feature is used to automatically re-transmit bursts in the event of a CRC24 error. The retransmission feature of the Integrated Interlaken IP core implements retransmission as defined in the Interlaken Retransmit Extension Protocol Definition, Revision 1.2, June 28, 2012.

Bursts need to be stored in a buffer in case they need to be re-transmitted. Because the number of bursts to be maintained is implementation-specific, the memory to store the bursts is external to the Integrated Interlaken IP core.

Retransmission is signaled over the slower out-of-band flow control (OOBFC) interface which has its own independent CRC checking. At least one bit in the OOBFC calendar is assigned to request retransmission. The position of this bit must be known to both ends of the interface.

The retransmission feature only works in burst-interleaved mode, as controlled by CTL_RX_PACKET_MODE. Retransmission is enabled with the CTL_TX_RETRANS_ENABLE and CTl_RX_RETRANS_ENABLE signals.

When the TX retransmission is enabled (CTL_TX_RETRANS_ENABLE = 1), you should not stall in the middle of a burst on the LBUS if tx_rdyout is asserted. This is required for reliable operation of retransmission.