Re: [icnrg] Fwd: New Version Notification for draft-gundogan-icnrg-ccnx-timetlv-01.txt
Cenk Gündoğan <mail+ietf@gundogan.net> Wed, 11 March 2020 11:20 UTC
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From: Cenk Gündoğan <mail+ietf@gundogan.net>
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Date: Wed, 11 Mar 2020 12:20:04 +0100
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Subject: Re: [icnrg] Fwd: New Version Notification for draft-gundogan-icnrg-ccnx-timetlv-01.txt
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Hello Marc, On Tue, Mar 10 2020 at 07:09 +0100, Mosko, Marc wrote: > I think this draft is very clear and easy to follow. The only addition I would make is to include an appendix with a few test vectors, say 0, a subnormal, and a normal or two. Or put them in the main text as examples. There are a few numbers in section 4: o Minimum subnormal number: 0 seconds o Maximum subnormal number: ~0.054688 seconds o Minimum normalized number: ~0.062500 seconds o Maximum normalized numbers: [~3.46, ~3.72, ~3.99] years we can put a few more into the appendix to show how the resolution degrades with higher numbers. That would be a good addition to the document. > > One question to consider is, would there be more possible time encodings beyond this? Do we need a way to clearly distinguish between time encodings for fields, or is inferring the encoding based on the length acceptable? I would probably rule out a nested encoding, as that is counter-productive when trying to introduce a 1 byte scheme. +1 to ruling out the nested TLV approach. Currently, there are only two TLVs that benefit from the compact timestamp encoding: InterestLifetime and RCT (in relative time form). For these, the currently defined, positive-only, 1-octet configuration (exponent=5,mantissa=3,bias=-5) is IMO sufficient. Using the TLV-Length as an indicator (L==1) has the advantage of being quite unobtrusive. It is not very flexible and extensible, though (as you pointed out). For future relative-time TLVs, we can also define another (sign,exponent,mantissa,bias) configuration (for L==1), if they require different properties, e.g., negative number support, microsecond resolution .. I currently cannot think of a reasonable use case that requires multiple configurations for a single relative-time TLV. We could also opt for a flat structure: New InterestLifetime / RCT / ... upper-level TLVs that reside next to the original TLVs (guarded with an exclusive or, since only one encoding for InterestLifetime / RCT / ... shall be used at the same time). This would require an update to the message structure BNF .. Cheers, Cenk > > Marc > > On 3/9/20, 12:03 PM, "icnrg on behalf of Cenk Gündoğan" <icnrg-bounces@irtf.org on behalf of mail=2Bietf=40gundogan.net@dmarc.ietf.org> wrote: > > Dear ICNRG, > > we updated our CCNx Time TLV draft to include the following changes: > > * we removed the previously included discussion on using a time base TLV > for (absolute) RecommendedCacheTime (RCT) TLVs in content objects. The > current approach interprets RCT as absolute (normal behavior) for UTC > timestamps (8 octets), and as relative for a compact timestamp (1 > octet). > > * we added an explicit configuration for exponent, mantissa, and bias to > Section 4. That configuration yields a milli second resolution for > lower time values and can also (with low resolution) reaches values > has high as ~4 years. > > * we added a few alternatives to section 5 (CCNx protocol integration) > to provide more material for discussions. This topic needs to converge > to a distinct solution, though. > > As always, any feedback is highly appreciated. > > Cheers, > Cenk > > On Mon, Mar 09 2020 at 19:42 +0100, internet-drafts@ietf.org wrote: > > > A new version of I-D, draft-gundogan-icnrg-ccnx-timetlv-01.txt > > has been successfully submitted by Cenk Gundogan and posted to the > > IETF repository. > > > > Name: draft-gundogan-icnrg-ccnx-timetlv > > Revision: 01 > > Title: An Alternative Delta Time encoding for CCNx using Interval Time from RFC5497 > > Document date: 2020-03-09 > > Group: Individual Submission > > Pages: 8 > > URL: https://www.ietf.org/internet-drafts/draft-gundogan-icnrg-ccnx-timetlv-01.txt > > Status: https://datatracker.ietf.org/doc/draft-gundogan-icnrg-ccnx-timetlv/ > > Htmlized: https://tools.ietf.org/html/draft-gundogan-icnrg-ccnx-timetlv-01 > > Htmlized: https://datatracker.ietf.org/doc/html/draft-gundogan-icnrg-ccnx-timetlv > > Diff: https://www.ietf.org/rfcdiff?url2=draft-gundogan-icnrg-ccnx-timetlv-01 > > > > Abstract: > > CCNx utilizes Delta Time for a number of functions. When using CCNx > > in environments with constrained nodes and/or bandwidth constrained > > networks, it is valuable to have a compressed representation of delta > > time. In order to do so, either accuracy or dynamic range has to be > > sacrificed. Since the current uses of delta time do not require both > > simultaneously, one can consider a logarithmic encoding such as that > > specified in RFC5497. This document updates _CCNx messages in TLV > > Format_ (RFC8609) to specify this alternative encoding. > > > > > > > > > > Please note that it may take a couple of minutes from the time of submission > > until the htmlized version and diff are available at tools.ietf.org. > > > > The IETF Secretariat > > > -- > Cenk Gündoğan > > Hamburg University of Applied Sciences > Dept. of Computer Science / Internet Technologies Group > Berliner Tor 7, 20099 Hamburg, Germany > Fon: +49 40 42875 - 8426 > Mail: cenk.guendogan@haw-hamburg.de > Web: https://www.inet.haw-hamburg.de/ > > > _______________________________________________ > icnrg mailing list > icnrg@irtf.org > https://www.irtf.org/mailman/listinfo/icnrg
- [icnrg] Fwd: New Version Notification for draft-g… Cenk Gündoğan
- Re: [icnrg] Fwd: New Version Notification for dra… Mosko, Marc <mmosko@parc.com>
- Re: [icnrg] Fwd: New Version Notification for dra… Cenk Gündoğan
- Re: [icnrg] Fwd: New Version Notification for dra… Mosko, Marc <mmosko@parc.com>
- Re: [icnrg] Fwd: New Version Notification for dra… Junxiao Shi
- Re: [icnrg] Fwd: New Version Notification for dra… Cenk Gündoğan