Re: [Fecframe] AD review draft-ietf-fecframe-raptor-07
Thomas Stockhammer <stockhammer@nomor.de> Fri, 24 February 2012 22:43 UTC
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From: Thomas Stockhammer <stockhammer@nomor.de>
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Date: Fri, 24 Feb 2012 23:43:04 +0100
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To: David Harrington <ietfdbh@comcast.net>
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Cc: draft-ietf-fecframe-raptor@tools.ietf.org, fecframe-chairs@tools.ietf.org, fecframe@ietf.org
Subject: Re: [Fecframe] AD review draft-ietf-fecframe-raptor-07
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Dave, all, great comments! Thanks! a new draft has been submitted addressing the comments as document inline. http://www.ietf.org/internet-drafts/draft-ietf-fecframe-raptor-08.txt > A slightly modified copy provided here: > <begin> > AD review draft-ietf-fecframe-raptor > > I have a number of concerns, mostly editorial. Please address these in > the > document and publish an updated ID. We are still waiting for the > updated IPR > disclosures from Qualcomm. It would be good if they were done against > the new > revision. > > 3) It is unclear whether the definitions here are the normative > definitions, or > whether they are normatively defined elsewhere. I recommend a minor > change: > /This document uses the following definitions./This document uses the > following definitions from [RFC6363]./ > /This document uses the following abbreviations/This document uses the > following abbreviations from [RFC6363]/ [T] The definitions and abbreviations are normatively and in addition to RFC6363. The new text is: "This document uses definitions that apply to FEC Framework in general as defined in RFC6363. In addition, this document uses the following definitions:" and the same for abbreviations > 4) this document and rtp-raptor share common introduction, but the > text differs > slightly. To make sure there are no inconsistencies that might impact > interpretation and interoperability, please use consistent wording in > both > documents. [T] The wording in the latest draft has been updated in the common parts. > 5)no security considerations specific to this document have been > identified. I > hope you mean no security vulnerabilities specific to these FEC > schemes have > been identified. please fix. > in 9, /No security considerations/No security vulnerabilities/+ [T] done > 6) in 1, s/sends the repair packet(s) along with the source packets/ > sends the repair packets and the source packets/ > > I recommend taking the first sentence of the next paragraph and move > it into > this bullet (what the sender must do). > > Then take the remaining sentences in that paragraph (what the receiver > should > do) and make them a bullet. [T] done > 7) in 1 s/if referred to/is referred to/ [T] done > 8) in 2, you mention MBMSTS and dvbts as reference tokens. These are > acronyms. > Please spell them out on first use. [T] done > 9) for all acronyms, please expand on first usage. e,g,. SPI. [T] SPI was added to the acronyms. Further checking for acronyms done. > 10) in 6.2.1.1, 7.2.1.1, and 8.2.1.1, you say XXX and YYY as assigned > by IANA. > But aren't there actually 6 different values to be considered? please > use 6 > different variables for the RFC Editor to modify to the six > iana-assigned > values. New names are - XXX(RFC5053-ARBITRARY) - XXX(RFC6330-ARBITRARY) - XXX(RFC5053-OPTIMISED) - XXX(RFC6330-OPTIMISED) - XXX(RFC5053-SINGLE) - XXX(RFC6330-SINGLE) > 11) in figure 1, you use a P-bit, which could be confused with > P=padding. Since > it represents the format, why not use a bit identified by something > that isn't > already used in FEC documentation? > If the payload ID format name is signaled by P=0 or P=1, and neither > "A" nor "B" > fit into a bit, then why not call them format 0 (where P-bit=0) and > format 1 > (where Pbit=1)? or simply say in the text "when P==0" or "P==1" or "P > is false" > or "P is true"? why introduce an extra set of variable names to keep > track of? [T] Despite this may be a good idea, this signaling is also used in other documents and it would be confusing to rename and change syntax and semantics now. I would only apply this if it is really considered a bug. > 12) in 6.2.1.2 you say maximum source block size is known as Kmax, but > in 7.3.2, > you use MSBL in your calculations. and elsewhere you use SBL for > source block > length. Why even bother mentioning Kmax if MSBL works fine? [T] I understand the confusion, but MSBL and Kmax are different. MSBL is a restriction for this scheme. Kmax is a restriction for the codes itself in RFC5053 and RFC6330. The text has been updated accordingly. > 13) in 5, ADUI[i] is the concatenation of FLRP, but the text has them > in RLFP > order. Any reason to not be consistent? If the terms were in > alphabetic order or > something, I'd understand. If the order is important for calculation > order, then > why not concatenate them in the same order? [T] The order has been changed on the text. > 14) in 6.2.1.2, "of the above" - I'm not sure what thing "the above" > refers to. > Please be more specific. [T] It is now explicitly referred to "FEC Scheme Specific Information" > 15) is the payload ID format identifier the same as the P-bit? Is the > format > signaled in the FEC Framework Configuration Information (section > 6.2.2) the same > as the P-bit? [T] Yes, this is more explicit now. > 16) 6.2.2 defines two formats, but never explains why two formats are > needed. [T] This explanation is added to section 6.2.2: "The two formats enable different use cases. Format A is appropriate in case the stream has many typically smaller source blocks and Format B is applicable if the stream has fewer large source blocks each with many encoding symbols." > 17) 6.2.3, undef figure 5, whcih depicts format B, you have text that > says "for > format A, it is of size 16 bits. [T] Done! It is 8 bit and format B > 18) in 6.2.3, it says "the interpretation ... is defined by the FEC > Code > Specification. Where do I find the FEC Code specification? [T] Reference is now made to RFC 5053 and 6330. > > 19) In 6.3.1, is "transport payload length" the length of the UDP or > RST packet? > or the length of the ADU payload? I tried to check this where l[i] is > defined, > but it said the scheme would tell me. [T] It is the ADU! This is clarified. > 20) the sentence conistruction in 6.3.3 is a little hard to parse; > could this be > rewritten? It might be a lot easier throughout the document if you > reduced the > "Raptor as defined in [RFC5052]" to just "Raptor [RFC5052]". [T] Done > For this particular paragraph, it might be better as: > "When using Raptor [RFC5053], ESI is calculated per [RFC5053] section > 5.3.2. > When using RaptorQ [I-D...], ESI is calculated per [I-D...] section > 4.4.2." [T] Done > > It might be even easier if you used mneumonic references for Raptor > and RaptorQ: > When using [Raptor], ESI is calculated as per [Raptor] section 5.3.2. > When using [RaptorQ], ESI is calculated as per [RaptorQ] section > 4.4.2. [T] Done > 21) in 7.2.x.x, you have extra spaces and missing spaces. [T] Done > 22) in 8.1.3, the order of elements is ISN/ESI/SBL for format A, but > ISN/SBL/ESI > for format B; why not use a consistent order of elements, e.g. make > format B > ISN/ESI/SBL to match format A? [T] Done > 23) in 8.2.1, why does the SBN wrap occur at 65535 and 255? In section > 6 and 7, > this is constrained by the SBN field size. But section 8 uses ISN, not > SBN, and > ISN for both formats is 16 bit, so why the constraint? [T] Correct, I have removed this sentence as it does not apply there. > > 24) in 8.2.2, parentheses would help differentiate I+(LB/LP)-1 from > I+LB/(LP-1). [T] Done > 25) Can LP ever be 0? [T] No > 26) Can this ever yield a negative number? I=0, (LB/LP)=0? [T] Good question. The question is more if there can be cases where no packets are included in the source block. or is LB always greater LP. This is added as a condition: The Source Block Length LB MUST be chosen such that it is at least as large as the largest Source Packet Information Length LP. > 27) are there any congestion control issues specific to these schemes? [T] No > 28) in 12, it says "this document registers three values ...", then > proceeds to > enumerate 6 values. [T] changed to 6 > should the even numbered ones be described as "the RaptorQ FEC scheme > for ..."? > rather than "the Raptor FEC scheme for ..., using raptorQ"? [T] changed! Great spotting! > 29) acknowldedgements - did anybody do a thorough review of the later > revisions > of the draft? [T] Yes, someone was added. > 30) id-nits shows some date-specific issues that need updating. [T] Checked and updated > <end> > > David Harrington > Director, IETF Transport Area > ietfdbh@comcast.net (preferred for ietf) > dbharrington@huaweisymantec.com > +1 603 828 1401 (cell) > --- Dr. Thomas Stockhammer (CEO) || stockhammer@nomor.de || phone +49 89 978980 02 || cell +491725702667 || http://www.nomor-research.com Nomor Research GmbH - Sitz der Gesellschaft: München - Registergericht: München, HRB 165856 – Umsatzsteuer-ID: DE238047637 - Geschäftsführer: Dr. Thomas Stockhammer, Dr. Ingo Viering.
- Re: [Fecframe] AD review draft-ietf-fecframe-rapt… Thomas Stockhammer