In this chapter
This chapter describes the port merging process, where frames from multiple ports on a
single SmartNIC are merged.
Each MAC outputs frames from a port on the SmartNIC. The port merger combines the frames from different ports and forwards them to the subsequent blocks.
The frames are time-stamped with the end-of-frame or
time when forwarded by the port merger. This is
done with an internal resolution of 1 ns. If two frames have exactly the same time stamp,
they are forwarded in port order (0, 1, ...).
Note: Start-of-frame time-stamping does not apply
to NT40E3-4-PTP SmartNICs running on the
capture/replay image, to NT40A01-4×10/1-SLB SmartNICs nor to the Intel® Programmable Acceleration Card with Intel® Arria®
10 GX FPGA.
Line-rate performance based on frame length
Line-rate frame handling is provided for frames according to the table in Performance
. Undersized frames (shorter than
might be discarded in the port merger, if such frames are received
frequently. However, the port merger contains a small buffer for each port, so bursts of
short frames can be handled and forwarded in the processing pipe.
Note: An NT200A01 running at 2 × 100 Gbit/s
ignores all frames shorter than 64 bytes.