Hi Robert,
Thanks for the information. If I understand it right, the 32 bit (4 bytes) Fraction Part in NTP is able to provide nanosecond precision. Then similarly for BMP, which currently uses 4 bytes for the “Timestamp (microseconds)” field, would it be more reasonable to defined the unit as nanosecond? Of course, microsecond precision might be sufficient for now. Yunan From: Robert Raszuk [mailto:rob...@raszuk.net] Sent: Wednesday, May 22, 2019 5:04 PM To: Guyunan (Yunan Gu, IP Technology Research Dept. NW) <guyu...@huawei.com> Cc: draft-ietf-grow-...@ietf.org; grow@ietf.org Subject: Re: [GROW] Timestamp question on RFC 7854 I don't think this is a typo - all looks fine. It all get's a bit more clear if you just look at NTP definition: NTP timestamps are represented as a 64-bit fixed-point number, in seconds relative to 0000 UT on 1 January 1900. The integer part is in the first 32 bits and the fraction part in the last 32 bits, as shown in the following diagram. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Integer Part | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Fraction Part | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ This format allows convenient multiple-precision arithmetic and conversion to Time Protocol representation (seconds), but does complicate the conversion to ICMP Timestamp message representation (milliseconds). The low-order fraction bit increments at about 0.2-nanosecond intervals ^^^^^^^^^^^^^^^^^^^^^^^^ Thx, R. On Wed, May 22, 2019 at 10:55 AM Guyunan (Yunan Gu, IP Technology Research Dept. NW) <guyu...@huawei.com<mailto:guyu...@huawei.com>> wrote: Dear authors, A maybe silly timestamp question on RFC7854. It is specified in Section 4.2: Timestamp: The time when the encapsulated routes were received (one may also think of this as the time when they were installed in the Adj-RIB-In), expressed in seconds and microseconds since midnight (zero hour), January 1, 1970 (UTC). If zero, the time is unavailable. Precision of the timestamp is implementation- dependent. I’m wondering is “microseconds” a typo here? “Milliseconds” sounds more reasonable. BR, Yunan Best Regards, [a] Yunan Gu Huawei Technologies Co. Ltd Beijing IP Technology Research Division 156 Beiqing Rd Phone: +86 15001353906 _______________________________________________ GROW mailing list GROW@ietf.org<mailto:GROW@ietf.org> https://www.ietf.org/mailman/listinfo/grow
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