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Re: [dtn] BPbis - time units

Carsten Bormann <cabo@tzi.org> Wed, 29 July 2020 05:47 UTC

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From: Carsten Bormann <cabo@tzi.org>
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Subject: Re: [dtn] BPbis - time units
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On 2020-07-29, at 03:09, Burleigh, Scott C (US 312B) <scott.c.burleigh=40jpl.nasa.gov@dmarc.ietf.org> wrote:
> 
> Hi.  At IETF-108 there was discussion on whether BP time fields (e.g., bundle creation time, lifetime, bundle age) should be denominated in seconds, milliseconds, microseconds, or nanoseconds.  Version 26 of the BPbis I-D (now posted) revises all time field definitions to be denominated in milliseconds.  

Note that CBOR has a choice of different time formats (tag 1, tag 1001), so if you want to provide a choice, you could allow the use of these in addition to assigning a default meaning to naked integers.  (These have a different epoch, but that is just a matter of subtracting a constant value; the representation needs one bit more which is making a difference between 2106 and 2030 next for whole seconds.)  Until 2106, tag 1 is shorter (6 bytes in total) than a naked integer in milliseconds (9 bytes).

(I don’t have an opinion on the actual question, but here is some data for that.)

Grüße, Carsten

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