Each packet that enters an ANIC adapter is tagged with a timestamp with up to 4nS (nanosecond) time precision. The ANIC adapter has to be disciplined from a timing source and there are five options as follows listed in order of popularity:
- Host OS – The host operating system acts as the time source and can in turn be disciplined by any other source such as PTP, 1PPS, NTP or the like.
- GPS/CDMA – ANIC adapter can be directly attached (via a front port) to a 1PPS (One Pulse Per Second) time source such as GPS or CDMA.
- PTP or IEEE 1588 – A PTP (Precision Time Protocol) network can be directly attached to an ANIC adapter via a front port.
- Another ANIC adapter – One ANIC adapter can be the time source for another by attaching them via the onboard “card-to-card bus”.
- Free Running – All timing is handled by the ANIC adapter onboard clock. This is the least precise mechanism but easiest to utilize.
An ANIC adapter can also parse out a Gigamon or Arista generated timestamp and propagate it forward to the host application.