Re: [straw] Review of draft-ietf-straw-b2bua-rtcp-10
Lorenzo Miniero <lorenzo@meetecho.com> Fri, 10 June 2016 10:29 UTC
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Date: Fri, 10 Jun 2016 12:29:30 +0200
From: Lorenzo Miniero <lorenzo@meetecho.com>
To: Ben Campbell <ben@nostrum.com>
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Cc: draft-ietf-straw-b2bua-rtcp.all@ietf.org, straw@ietf.org, Christer Holmberg <christer.holmberg@ericsson.com>
Subject: Re: [straw] Review of draft-ietf-straw-b2bua-rtcp-10
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On Thu, 09 Jun 2016 15:51:41 -0500 "Ben Campbell" <ben@nostrum.com> wrote: > Hi, > > Comments to your email inline. I removed sections that don't seem to > need further discussion. I will send any comments about the new draft > revision separately. > Hello Ben, thanks for the additional comments! I just pushed a new version of the document that addresses the final points of the discussion. I'll also send a new mail to the list shortly to foster discussion on the "standards track vs BCP" scope for the document, as you suggested. Thanks, Lorenzo > Thanks! > > Ben. > > On 31 May 2016, at 6:12, Lorenzo Miniero wrote: > > > On Fri, 27 May 2016 17:17:35 -0500 > > "Ben Campbell" <ben@nostrum.com> wrote: > > [...] > > > > > > > Hello again, Ben, > > > > I just posted a new version of the document (an announcement should > > get > > to the ML soon) that tries to address most, if not all, of your > > points. > > You can find some additional comments inline on the parts I haven't > > addressed yet (or I only partly addressed), for one reason or > > another. To make this more readable, I snipped the parts that I > > already integrated. > > > > > >> > >> * The intended status is proposed standard. Do people really expect > >> b2bua vendors to implement the rules in this draft? Do they expect > >> existing b2bua implementations to be updated? > >> > > > > > > I already answered to this in my previous mail, but just to > > reinstate, I'll leave the decision to WG and chairs/ADs as to what > > the intended status should be. I personally would keep it a > > proposed standard, but again wouldn't object to a BCP, if needed. > > > > Let's leave this as PS for now, but realize that may change at some > point as we go forward. As far as getting the WG's opinion goes, it > might be worth it to send a separate email to the list about this one > question. Otherwise people may miss it buried in the rest of the > review comments. > > > > > >> > >> * Section 3, last paragraph - This paragraph seems to argue that > >> the fact that > >> existing b2buas do not follow specs is a reason to create more > >> specs. That seems > >> questionable. > >> > > > > > > Fair point. I haven't changed that part in the doc yet, as I wanted > > to be sure I'd get it right, first. Do you think it would be ok to > > say something along the lines of "due to the mixed nature of > > B2BUAs, they sometimes can't or won't implement all specifications, > > so they should at least do this"? > > I think that logic is reasonable. > > [...] > > > > > > >> > >> * Section 4 > >> * Last paragraph, 2nd to last sentence - If you think people > >> will really pay attention, > >> then this might be a good place for a MUST or SHOULD > >> > > > > > > Do you mean where we say "behaviour is unspecified and > > discouraged"? Or > > more in general about the fact that a B2BUA can only follow the > > guidelines when it has access to editing fields without breaking > > hashes? Not sure which MUST or SHOULD we might add there, > > considering that, if the media the B2BUA is encrypted, it can't > > possibly edit RTP related information without disrupting the > > communication, which in turn means no RTCP editing will be > > needed/possible either. > > > > Do you think a "B2BUAs MUST NOT modify RTP/RTCP data if media is > > encrypted" to be enough, in case? > > In retrospect, I wrote that comment without thinking about it in > context of b2bua-dtls-srtp. Since you already reference that draft, I > withdraw that comment. No change is really needed. > > > > >> > >> * Third paragraph: > >> * "It SHOULD NOT, though, blindly forward all SDP > >> attributes," > >> - Isn’t > >> the idea that it should forward any attributes that it > >> doesn’t > >> have a specific reason not to forward? (i.e. default to > >> forwarding?) > >> > > > > > > The issue here is the reason not to forward itself. In order to > > figure out whether an attribute can be forwarded or not, the B2BUA > > must have some knowledge of it and of its impact. What I wanted to > > highlight in that sentence is that there are attributes that, if > > left where they are > > by a B2BUA unaware of their purpose, can actually cause issues. Just > > think, for instance, of 'rtcp' attribute that is explained in the > > text, > > or other attributes supporting features a B2BUA may not support > > itself. > > > > Aren't those attributes that the b2bua must, by definition, know > about and have a "specific reason" not to forward. > > > Of course, as you point out there could be reasons to actually keep > > attributes you don't know about in there, e.g., because they > > advertize support for an end-to-end feature the B2BUA doesn't need > > to worry about. Besides, the attributes that can cause issues are > > probably not that many anyway. > > Right. One of the big issues with b2buas is that they tend to make > SIP networks brittle to new features. I think we need to discourage > that as much as possible. I realize we can't write guidance on how to > handle a "foo" attribute that works in all cases of "foo", but we can > at least err on the side of letting things through. > > > > > > > I'll think about a way to make this clearer in the next for next > > version. > > Okay. >
- [straw] Review of draft-ietf-straw-b2bua-rtcp-10 Ben Campbell
- Re: [straw] Review of draft-ietf-straw-b2bua-rtcp… Lorenzo Miniero
- Re: [straw] Review of draft-ietf-straw-b2bua-rtcp… Lorenzo Miniero
- Re: [straw] Review of draft-ietf-straw-b2bua-rtcp… Ben Campbell
- Re: [straw] Review of draft-ietf-straw-b2bua-rtcp… Ben Campbell
- Re: [straw] Review of draft-ietf-straw-b2bua-rtcp… Christer Holmberg
- Re: [straw] Review of draft-ietf-straw-b2bua-rtcp… Lorenzo Miniero
- Re: [straw] Review of draft-ietf-straw-b2bua-rtcp… Ben Campbell
- Re: [straw] Review of draft-ietf-straw-b2bua-rtcp… Lorenzo Miniero