Transmit Segmented AXI4-Stream - 2.1 English

Versal ACAP 600G Channelized Multirate Ethernet Subsystem (DCMAC) LogiCORE IP Product Guide (PG369)

Document ID
Release Date
2.1 English

In the non-channelized segmented mode, frames span bus segments and the user logic can start or end a frame in any given segment. In modes with four or more segments, frames can start and end on the same cycle. For the 400G mode, with eight segments, two frames can start in a single cycle and two preamblein buses are consequently available; tx_preamblein_0 is used for frames starting in segments 0 to 3 while tx_preamblein_2 is used for frames starting in segments 4 to 7.

Note: The odd-numbered preamble buses are only used in non-channelized 100G modes.

The general rule of segmentation is that new SOPs must be aligned to segment 0. “New” is defined as either the first frame after port startup or the start of a frame when the last valid cycle ended with an eop (on any segment, but correspondingly followed by disabled segments if eop was not on the last segment of the bus). Start-of-frame indications can occur on other segments, but only if they immediately follow an eop on the preceding segment. There can be no gaps (that is to say, segments with ena deasserted) between eop and sop on a single cycle.