Limitations of the transmit on time stamp feature.
This list describes some limitations of the transmit on time stamp feature:
- To preserve the relative timing of frames transmitted using a given port, only one host buffer per port is supported.
- Other types of transmission are not supported on a port enabled for transmit on time stamp.
- PCAP files must contain frames captured from a single port, since the PCAP descriptor does not contain port number information.
- All frames must be specified in chronological order, that is with increasing time stamps. If this is not the case, the relative timing between frames cannot be guaranteed.
- For synchronized transmit on time stamp across multiple ports, the SmartNICs involved must be time-synchronized, and all frames must share a common notion of time.
- Replay of capture files at 2×40 Gbit/s and 100 Gbit/s line rates may require memory-mapped files.
- On NT200A02 and NT200A01 running at 2 × 100 Gbit/s, full line rate transmission is not possible on the two ports simultaneously, as the PCIe3 bandwidth is only approximately 100 Gbit/s.