Re: [bfcpbis] PROTO review comments on draft-ietf-bfcpbis-rfc4583bis-08
Tom Kristensen <2mkristensen@gmail.com> Thu, 13 February 2014 14:50 UTC
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References: <CAHBDyN58t7b0jJC3UcWB8fEASSApjje_Raz-06k88n90ZoKK7w@mail.gmail.com> <52D7F10B.5070401@cisco.com> <CF0823C7.1BA53%eckelcu@cisco.com>
Date: Thu, 13 Feb 2014 15:50:39 +0100
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From: Tom Kristensen <2mkristensen@gmail.com>
To: "Charles Eckel (eckelcu)" <eckelcu@cisco.com>
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Cc: "draft-ietf-bfcpbis-rfc4583bis.authors@tools.ietf.org" <draft-ietf-bfcpbis-rfc4583bis.authors@tools.ietf.org>, "bfcpbis-chairs@tools.ietf.org" <bfcpbis-chairs@tools.ietf.org>, "Tom Kristensen (tomkrist)" <tomkrist@cisco.com>, Richard Barnes <rlb@ipv.sx>, "bfcpbis@ietf.org" <bfcpbis@ietf.org>, Mary Barnes <mary.ietf.barnes@gmail.com>
Subject: Re: [bfcpbis] PROTO review comments on draft-ietf-bfcpbis-rfc4583bis-08
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All the issues here are resolved inline in line with Mary's suggestions - as adjusted and commented by Charles and myself in this thread. The upcoming version will include the changes. -- Tom On 24 January 2014 23:41, Charles Eckel (eckelcu) <eckelcu@cisco.com> wrote: > On 1/16/14 6:47 AM, "Tom Kristensen (tomkrist)" <tomkrist@cisco.com> > wrote: > > >I went through and commented on this in my favourite editor (Emacs > >obviously), but forgot to paste it in and respond until now. I have > >updated my comments to align with Charles Eckel's recent response too. > > Thanks for that. More inline. > > > > >Inline below. > > > > > >On 12/18/2013 11:38 PM, Mary Barnes wrote: > > > Hi all, > > > > > > I have agreed to shepherd this document on behalf of the WG. I have > > > reviewed this document in preparation for doing the PROTO write-up. > > > > > > I think the document needs a bit of work before it's ready to progress. > > > I have a few questions/comments, as well as editorial nits which I > >think > > > would improve readability and ease of understanding. > > > > > > _General Comments:_ > > > > > > The document requires an SDP directorate review prior to progressing. I > > > have requested that of the MMUSIC WG chairs. At the time of this > >review, > > > Ali Begen has agreed to do that review. > > > >Yes, I have commented on his issues on the MMUSIC mailing list. > > > > > _Comments/Questions:_ > > > > > > 1) I am slightly puzzled by the following in section 3: > > > > > > m=<media> <port> <transport> <fmt> ... > > > > > > Section 5.14 of RFC 4566 states the following: > > > > > > m=<media> <port> <proto> <fmt> ... > > > > > > So, this looks to be like the RFC 2327 ABNF for m lines is being used > > > (rather than RFC 4566 which is the normative SDP specification for this > > > document)? > > > > > > m=<media> <port> <transport> <fmt list> > > > > > > Note, that the IANA registration section appears to be based on RFC > >4566 > > > as the values are specified as being applicable to the 'pro to' field. > > > So, my guess is that this is a bug from RFC 4583. > > > >Yes, an inherited bug that will be fixed without complications. > > > > > 2) Section 3, next to last paragraph. I think it would be more precise > > > to reword this as: > > > > > > OLD: > > > > > > The fmt (format) list is ignored for BFCP. The fmt list of BFCP 'm' > > > lines SHOULD contain a single "*" character. > > > > > > NEW: > > > > > > The fmt (format) list is not applicable to BFCP. The fmt list of 'm' > > > lines in the case of any proto field value related to BFCP SHOULD > > > contain a single "*" character. If the the fmt list contains any other > > > value it is ignored. > > > >Agree. That is a more precise wording for the fmt part. > > > >Charles Eckel touched upon this as well and was okay with this, > >especially if there are known reasons and/or implementations that > >already do otherwise. Well, once upon a time there was a SIP based > >product from a (large french) vendor that used 0 (I think) - don't think > >that product is still maintained. But it might be out there in the wild > >still. Will fix. > > > > > 3) Section 4, paragraph above table 1, 1st sentence. I suggest for > > > clarification to make the following change: > > > > > > OLD > > > > > > MUST include one in the corresponding media description > > > > > > NEW > > > > > > MUST include a 'floorctrl' attribute in the corresponding media > >description > > > >Fine with me, will update. > > > > > 4) Section 4, 3rd paragraph from the end: > > > > > > "Endpoints that use the offer/answer model to establish BFCP > >connections > > > MUST support the 'floorctrl' attribute. A floor control server acting > >as > > > an offerer or as an answerer SHOULD include the attribute in its > >session > > > descriptions." > > > > > > Since the latter is a SHOULD what happens if the attribute is NOT > > > included? Under what circumstances is it okay for the server not to > > > include it? IF bad things happen if it's not included, then this > > > probably ought to be a MUST. Or, if there's reasonable situations in > > > which the floor control server doesn't include the attribute, those > > > should be explained or at least an example provided. > > > >The default behaviour/assumption if the 'floorctrl' attribute is not > >used is explained in the paragraph below, i.e. offerer == client and > >answerer == server. > > > >I agree that the formulation "is not used in an offer/answer exchange" > >might point towards usage other than offer/answer, but the sentence > >continues with explaining what the offerer and answerer will assume. So > >fine with me. OK? > > > >If not, I will not object using MUST here - as also proposed by Charles > >Eckel. > > > > > 5) Section 7. > > > > > > a) 1st paragraph after ABNF. "..versions SHOULD be integers..". I would > > > think that ought to be a MUST. What happens if the token isn't an > > > integer and what was the motivation for not defining the version as an > > > integer versus a token? If non-integers can be used, the scope of what > > > is acceptable for the field needs to be explained. > > > >I agree, this will be upgraded to a MUST if people doesn't object. > > > >And if this will ever change non-integer versions must be specified in > >another draft/RFC and this draft probably have to be updated as well - > >since semantics for specific versions are specified later in Section 7. > > > > > b) 2nd paragraph after ABNF. I can see why supporting the version is a > > > SHOULD (since it is a new field) and RFC 4583 did not define a version, > > > but I think that needs to be more clearly documented and I think it > > > ought to be REQUIRED for anyone that is using UDP and obviously, older > > > implementations of TCP (i.e., those only compliant to RFC 4583 and not > > > this document) ought to be the only ones that aren't using the version > > > field. > > > >Is it sufficient to merge in the following sentence after the second > >sentence in that paragraph? > >"However, endpoints that supports RFCXXXX, and not only the RFC 4583 > >subset, is REQUIRED to support and use the 'bfcpver' attribute." > >(Or something along those lines). > > Works for me, though should be "endpoints Š are". > > > > >A complicating factor here is that some pre-standard implementations, as > >experienced on recent SIPit and SuperOp test events, is out there and is > >not using the 'bfcpver' attribute. However, demanding that > >implementations following the new RFC from this draft have to use the > >version attribute should be perfectly fine. > > Agreed, and stating that when omitted the default is "1" for TCP and "2" > for UDP addresses the problem of pre-standard UDP implementations as well. > > > > > > c) last paragraph. Related to b, I would think that in the case of > > > unreliable transports, it's not that an endpoint MUST "assume". An > > > endpoint MUST "use" and signal a version number of 2. In the case of a > > > reliable transport, if the endpoint does not signal a > > > bfcpversion-attribute, then the floor control server MUST use a value > >of > > > 1. I'm recalling a fair amount of mailing list discussion on this one, > > > so if you can point to the thread where this text was agreed, I can let > > > this one go. I still think it's not specified quite right, but I can > > > live with it. > > > >I can't find too much discussion about this, but I agree that the word > >"assume" is not good here. What about reformulating this last paragraph > >to: > > > >"If a 'bfcpver' attribute is not present, default values are based on > >the transport specified in the m-line (Section 3). When used over an > >unreliable transport, an endpoint MUST use a value of "2", and when used > >over a reliable transport, an endpoint MUST use a value of "1". This is > >in line with the definition of the Version field in [8]." > > > >Any better? > > Better, but how about: > > "If a 'bfcpver' attribute is not present, default values are inferred from > the transport specified in the m-line (Section 3). In accordance with > definition of the Version field in [8], when used over a reliable > transport the default value is "1", and when used over an unreliable > transport the default value is "2". > > > > > > > 6) Section 8. 1st sentence. I think this should be a "can use TCP or > > > UDP" and not a "may use TCP or UDP". Note, there is the perennial > >debate > > > with regards to whether something is normative even when it's not CAPS. > > > I prefer to just use a different word to remove any confusion, > > > particularly when a different word is actually more correct. > > > >Well explained, the change is fine with me. > > > > > 7) Section 8.1, 4th paragraph, 1st sentence and last sentence. I think > > > the two "SHOULD generate and offer" ought to be a MUST generate an > >offer > > > OR you need to specify the circumstances under which a client would not > > > generate an offer. > > > >OK > > > > > 8) Section 9, 1st paragraph. You're going to have to be more specific > > > about the potential mechanisms for authentication - at least provide an > > > example of mechanisms - i.e., I don't think "some mechanism" will fly > > > with the SecDir folks. > > > >Too bad, since this is inherited from RFC 4583 - but of course that text > >wasn't perfect ;) > >Anyway, isn't the mechanisms meant here mentioned in the paragraphs > >below? If so, might extending to "using some mechanism, as explained > >below" be a valid solution in front of the SecDir review? > > > >Or as Charles Eckel proposed, pointing towards TLS/DTLS as the preferred > >mechanism, but other mechanisms exists but are outside the scope of this > >document. > > This still works for me :) > > Cheers, > Charles > > > > > > 9) Section 11, 2nd paragraph. I think that the assumes in the following > > > statement needs to be a required. I suggest the following change: > > > > > > OLD > > > > > > BFCP assumes that an initial integrity-protected channel is used to > > > exchange... > > > > > > NEW > > > > > > An initial integrity-protected channel is REQUIRED for BFCP to > >exchange... > > > >Yes, I'll adopt that one. No assumption, we will require! > > > > > 10) Related to item 7, this list of changes has no mention of the new > > > "bfcpver" attribute. That definitely should be on this list. > > > >Indeed! It's missing since it arrived late, but that's just a poor > >excuse... > > > > > > > _Editorial nits:_ > > > > > > 1) Introduction. "These data includes..." -> "This data includes...." > > > (data is now grammatically considered to be a singular noun). > > > >OK > > > > > 2) Section 3. 1st paragraph after the indented text. This could be > > > written more concisely (and per technical doc standards not as the 1st > > > person) as follows (and per comment 1) above, I think this should be > >the > > > 'proto' field: > > > > > > OLD: > > > > > > We define four new values for the transport field: > > > > > > NEW: > > > > > > This document defines four values for the proto field: > > > >OK > > > > > 3) Section 5. I suggest the following change: > > > > > > OLD: > > > > > > We define the 'confid' and the 'userid' SDP media-level attributes. > > > > > > NEW: > > > > > > This document defines two SDP media-level attributes: 'confid' and > >'userid'. > > > >OK > > > > > 4) Section 6. I suggest the following change: > > > > > > OLD: > > > > > > We define the 'floorid' SDP media-level attribute. > > > > > > NEW: > > > > > > This document defines the 'floorid' SDP media-level attribute. > > > >OK > > > > > 5) Section 13. I found this really, really hard to read. I suggest you > > > use a bulleted or numbered list versus this hanging list style. > > > >Sure, I'll tweak the XML curses and make it more readable. > > > > > >-- Tom > >_______________________________________________ > >bfcpbis mailing list > >bfcpbis@ietf.org > >https://www.ietf.org/mailman/listinfo/bfcpbis > > _______________________________________________ > bfcpbis mailing list > bfcpbis@ietf.org > https://www.ietf.org/mailman/listinfo/bfcpbis > -- # Cisco | http://www.cisco.com/telepresence/ ## tomkrist@cisco.com | http://www.tandberg.com ### | http://folk.uio.no/tomkri/
- [bfcpbis] PROTO review comments on draft-ietf-bfc… Mary Barnes
- Re: [bfcpbis] PROTO review comments on draft-ietf… Charles Eckel (eckelcu)
- Re: [bfcpbis] PROTO review comments on draft-ietf… Tom Kristensen
- Re: [bfcpbis] PROTO review comments on draft-ietf… Charles Eckel (eckelcu)
- Re: [bfcpbis] PROTO review comments on draft-ietf… Tom Kristensen