Data Formatting - Data Formatting - 1.2 English - PG209

The transmit logic of the Interlaken 600G IP core segments inbound packets into bursts as described in the Interlaken Protocol Definition, Revision 1.2. On the Interlaken interface, a burst is a sequence of 64-bit Data Words Word between two 64-bit Control Words. The first of those two Control Words must be a Burst Control Word and it indicates the channel number associated with the burst and whether the burst is the SOP. The size of the bursts generated by the Interlaken 600G IP core is controlled by these factors:

• Configuration inputs ctl_tx_burstmax and ctl_tx_burstshort
• How packets are written to the TX LBUS

You can explicitly force Burst Control Words on the TX Interlaken interface at the TX LBUS either by assertion of tx_sopin<N> or tx_bctlin<N>, or through a change of channel on tx_chanin<N>. Furthermore, a Burst Control Word is implied by the transmit logic in the Interlaken 600G IP core when it reaches a value of BurstMax data bytes transmitted after it last sent a Burst Control Word. The Interlaken 600G IP core imposes a limit on the number of Burst Control Words, implied or forced, that can be associated with the data present on the LBUS in a given clock cycle. Specifically, the core requires that there be at most TX_LBUS_WIDTH/512 Burst Control Words per clock cycle. Consequently, for a 2,048-bit LBUS, at most four Burst Control Words (implied or forced) can occur in the same cycle. Similarly, for a 1,536-bit LBUS, at most three Burst Control Words (implied or forced) can occur in the same cycle. If this requirement is violated, the signal stat_tx_burst_err is asserted and data loss can occur.

The Interlaken 600G IP core operates in one of two modes, depending on how the data is written to the TX LBUS:

• Packet Mode
• Burst-Interleaved Mode