tcpdump mailing list archives
Re: DLT request for EBHSCR
From: Ebermann, Günter <Guenter.Ebermann () elektrobit com>
Date: Mon, 21 Jan 2019 13:31:43 +0000
From: Guy Harris [mailto:gharris () sonic net]
On Sep 25, 2018, at 6:16 AM, Guenter.Ebermann () elektrobit com wrote:I have updated http://www.elektrobit.com/ebhscrSo what is the origin of the scale for the time stamps? For BroadR-Reach, I'm guessing, from The timestamp is taken after the end of the SFD (Start of Frame Delimiter) detection, as specified in the IEEE 1588 Specification Sep- 2004 (IEC 61588 First Edition). that the origin is 1970-01-01 00:00:00 TAI (TAI, not UTC). Is that correct?
Sorry for the late answer. The origin of the time stamps is not defined. We only take the definition of the time stamp point out of IEEE 1588 - because this is what Ethernet MACs and PHYs are doing if they have hardware timestamping support. But not every capture device may be time synced with external sources like GPS or Ethernet PTP. So perhaps they only have a local running counter they are using for timestamping. That's the reason why we did not specify the origin of the scale of the time stamp. BR Günter _______________________________________________ tcpdump-workers mailing list tcpdump-workers () lists tcpdump org https://lists.sandelman.ca/mailman/listinfo/tcpdump-workers
Current thread:
- Re: DLT request for EBHSCR Ebermann , Günter (Jan 21)