Hello Pete, Please accept our sincere thanks for your time reviewing and commenting on this draft. Your comments do help us shape a better draft. Please see answers and questions inlined in your text. Best regards Dominique Le 07/08/19 05:13, « Pete Resnick via Datatracker » <noreply@xxxxxxxx> a écrit : >Reviewer: Pete Resnick >Review result: Ready with Issues > >I am the assigned Gen-ART reviewer for this draft. The General Area >Review Team (Gen-ART) reviews all IETF documents being processed >by the IESG for the IETF Chair. Please treat these comments just >like any other last call comments. > >For more information, please see the FAQ at > ><https://trac.ietf.org/trac/gen/wiki/GenArtfaq>. > >Document: draft-ietf-lpwan-ipv6-static-context-hc-21 >Reviewer: Pete Resnick >Review Date: 2019-08-06 >IETF LC End Date: 2019-07-19 >IESG Telechat date: Not scheduled for a telechat > >Summary: > >Some minor issues, but otherwise looks good to me. > >My apologies for this very late review. I hope these comments are useful, >but >none of these are showstoppers in my opinion. > >Major issues: > >None. > >Minor issues: > >Section 5: > > If the SCHC > Packet is to be fragmented, the optional SCHC Fragmentation MAY be > applied to the SCHC Packet. > >Don't you mean: > > If the SCHC Packet is to be fragmented, the OPTIONAL SCHC > Fragmentation is applied to the SCHC Packet. > >or even just: > > SCHC Fragmentation is applied if the SCHC Packet is to be fragmented. > >I think it's confusing to say that using SCHC is optional if the SCHC >Packet is >to be fragmented. If you're fragmenting, it's not optional, is it? DB: some LPWAN technologies have their own fragmentation technique (e.g. NB-IoT), and as part of their Profile, they might want to specify that SCHC Fragmentation shall not be used. In such a case, even though fragmentation is needed, SCHC Fragmentation is not used. How about OLD TEXT If the SCHC Packet is to be fragmented, the optional SCHC Fragmentation MAY be applied to the SCHC Packet. NEW TEXT If needed by the underlying layer, the optional SCHC Fragmentation MAY be applied to the SCHC Packet. > >Section 7.1 or 7.3: > >It took me a while to get that what you're looking for is a Rule in the >list of >Rules that has a function for *all* of the header fields given the DI and >FP. >It would be good to say some sort of overview thing like this explicitly, >either in 7.1 or at the top of 7.3. It's possible this is obvious to >someone >versed in this topic, but it wasn't for me. [DB] your proposed rephrasing is not quite accurate. We are looking for a Rule that has a function for all of the header fields and *no more* than the header fields in the packet being compressed. This is reflected in the detailed algorithm. Regarding an overview statement, how about changing OLD TEXT the set of Rules is browsed to identify which Rule will be used to compress the packet header. The Rule is selected by matching the Fields Descriptions to the packet header. The detailed steps are the following: NEW TEXT the general idea is to find in the Rule set a Rule that has a matching Field Descriptor (given the DI and FP) for exactly each and every header field of the packet being compressed. The detailed algorithm is the following: Also, I realised we use the word "steps" at two indentation levels. I suggest we change OLD TEXT The compression/decompression process follows several steps NEXT TEXT The compression/decompression process follows several phases > >Section 7.3: > >Question: Is it possible for multiple Rules to match a given packet? What >happens if you find more than one? That should probably be specified. DB: indeed, this specification does not prevent multiple Rules from matching. We have kept silent about this in order to keep the text small and to avoid ensuing discussions. But since you're asking, how about adding the following? NEW TEXT This specification does not prevent multiple Rules from matching. Whether a multiple match is allowed or not, and what to do in the case where multiple Rules match, is left to the implementation. A long as the same Rule set is installed at both ends, this degree of freedom does not constitute an interoperability issue. > >Section 7.5.2: > >This encoding seems to use more space than needed. I assume you kept the >size >in multiples of 4 to make it on nibble boundaries, but I don't understand >why >you'd want 28 bits instead of 24. The larger sizes could simply be 0xFF >followed by the 16-bit value. [DB] I don't quite understand his proposal. Is it a two-sized approach (4 bits and 24 bits), or a three-sized approach (4, 12 and 24 bits). In the former case, we pay a high cost for value sizes 15 and upward. In the latter case, the intermediate size (12 bits) is only applicable to value size 15 (or 15-31?). I like the three-sized approach and suggest we don't change our current spec. We expect the 4 and 12 bits encodings to be used most of the time, and added the 24 bits encoding as a safety net. > >Nits/editorial comments: > >Section 7.3: > >In the last bullet of the Rule selection algorithm, it says: > > Sending an uncompressed header may require SCHC F/R. > >Sending a compressed header may also require F/R, couldn't it? Seems to >me this >sentence is superfluous. DB: you're right, in a pure logic sense. The aim of "may" was to attract attention to the likeliness that fragmentation be required. Another reviewer suggested OLD TEXT Sending an uncompressed header may require SCHC F/R. NEW TEXT Sending an uncompressed header is likely to require SCHC F/R. > >Section 8.1, second paragraph: > >It seems like you'd want one or both occurrences of "optional" to be >"OPTIONAL", in the 2119 sense. Is there a reason they're not? DB: True, thanks for catching this. The second one should be capital letters. > >I'm not sure I understand the last sentence of that paragraph. Do you >simply >mean, "You can ignore the rest of section 8"? That seems unnecessary to >say. DB: thanks for your opinion on this. We will remove this sentence. > >Section 8.2.2.2: > >Change: > > o their numbers MUST increase from 0 upward, from the start of the > SCHC Packet to its end. > >to: > > o their numbers MUST increase by 1 from 0 upward, from the start of > the SCHC Packet to its end. > >in order to avoid someone being inordinately cute (or stupid). DB: Definitely true, this was a shortcoming of ours. We'll change this text to say "increment by 1" or "increase by 1" as suggested. > >8.2.4: > >"The W field is optional" - Is OPTIONAL not appropriate here? If so, this >appears in many places in section 8. DB: True. I haven't paid enough attention to the use of capital OPTIONAL, overall. I will give it another pass. _________________________________________________________________________________________________________________________ Ce message et ses pieces jointes peuvent contenir des informations confidentielles ou privilegiees et ne doivent donc pas etre diffuses, exploites ou copies sans autorisation. Si vous avez recu ce message par erreur, veuillez le signaler a l'expediteur et le detruire ainsi que les pieces jointes. Les messages electroniques etant susceptibles d'alteration, Orange decline toute responsabilite si ce message a ete altere, deforme ou falsifie. Merci. This message and its attachments may contain confidential or privileged information that may be protected by law; they should not be distributed, used or copied without authorisation. If you have received this email in error, please notify the sender and delete this message and its attachments. 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