Paul Kyzivat <pkyzivat@xxxxxxxxx> 写于 2010-04-14 22:23:57:
> inline
>
> gao.yang2@xxxxxxxxxx wrote:
> >
> > Hi Shinji,
> >
> > Please see inlines.
> >
> > Thanks,
> >
> > Gao
> >
> > sipping-bounces@xxxxxxxx 写于 2010-04-12 10:55:47:
> >
> > > Hi Gao,
> > >
> > > The clarifications for the section 13.2.1 of RFC 3261 is
> > > one of the major purposes in this draft.
> > >
> > > In the section 3.1 of this draft,
> > > | 3.1. Offer/Answer for the INVITE method with 100rel extension
> > > | (snip) All the session
> > > | descriptions in the unreliable responses to the INVITE request must
> > > | be identical to the answer which is included in the reliable
> > > | response.
> > >
> > > Do you doubt this clarification?
> > > In my understanding, this has already reached the consensus in WG.
> >
> > [Gao] I am not want to *challenge* the consensus we have reached in WG.
> > But as this draft is aims for clarification, not for normative
> > correction, I have no way to convince the *UAS*.
>
> (I just posted a related reply to a later message in this thread.)
>
> Whether this clarification is supported by the existing normative text
> is worthy of some careful thought.
>
> As I noted in the other reply, a UAS sending multiple *unreliable*
> responses with SDP must assume that some or all of them will be lost. If
> these SDPs have different values, and the UAC processes the first it
> receives, and ignores the rest, then the resulting behavior will be
> indeterminate.
Yes. So, I think finally using the real answer in the first reliable response can making the final session determinate.
But in your case, UAC would have a indeterminate early media, depending on which SDP is the one it first receives.
>
> IMO this is sufficient to infer that there is only one meaningful
> interpretation, so that a clarification is sufficient without a
> normative change.
I don't catch this point. Could you say it more.
Thanks,
Gao
>
> Thanks,
> Paul
>
> > >
> > > I'm confused.
> > > Do you have something a concrete proposal?
> >
> > [Gao] I think the original illegibility is from RFC3261. So, I sended
> > mails about it in SIPCore ML:
> >
> > http://www.ietf.org/mail-archive/web/sipcore/current/msg02315.html
> > http://www.ietf.org/mail-archive/web/sipcore/current/msg02328.html
> >
> > To be honest, I think there are two options here:
> > 1. Forbid different SDP(compare with the answer) before the answer
> > normatively.
> > 2. Allowing different SDP(compare with the answer) before the answer
> > normatively.
> >
> > >
> > > Just to be sure, this draft is not a normative document but
> > > an informational one as you no doubt know.
> >
> > [Gao] Sure, I know it is informative.
> >
> > >
> > > Regards,
> > > Shinji
> > >
> > > gao.yang2@xxxxxxxxxx
> > > Fri, 9 Apr 2010 16:50:12 +0800
> > > >Hi Shinji,
> > > >
> > > >Thanks firstly.
> > > >
> > > >But the UAS do not think it throws the problem. RFC3261 said UAS may
> > send
> > > >the same SDP before the answer, but there is not normative words of to
> > > >forbid the different SDPs.
> > > >
> > > >And if the equipment has been in the network, unless we using the
> > evident
> > > >standard, we has no way to request their correction.
> > > >
> > > >Gao
> > > >
> > > >OKUMURA Shinji <shinji.okumura@xxxxxxxxxxxx>
> > > >发件人: sipping-bounces@xxxxxxxx
> > > >2010-04-09 16:30
> > > >
> > > >收件人
> > > >sipping@xxxxxxxx
> > > >抄送
> > > >
> > > >主题
> > > >Re: [Sipping] About offeranswer draft:
> > > >
> > > >Hi Gao,
> > > >
> > > >In this case it is no doubt the UAS is a cause of the problem.
> > > >All you have to do is say "Your UAS is against the rules".
> > > >You will surely win the fight.
> > > >
> > > >Regards,
> > > >Shinji
> > > >
> > > >gao.yang2@xxxxxxxxxx
> > > >Fri, 9 Apr 2010 15:25:58 +0800
> > > >>Hi Shinji,
> > > >>
> > > >>By myself, I am OK with the three ways. But if there's no normative
> > > >>definition here, there would be some interworking fight for this issue.
> > > >>
> > > >>Thanks,
> > > >>
> > > >>Gao
> > > >>
> > > >>OKUMURA Shinji <shinji.okumura@xxxxxxxxxxxx>
> > > >>发件人: sipping-bounces@xxxxxxxx
> > > >>2010-04-09 14:23
> > > >>
> > > >>收件人
> > > >>sipping@xxxxxxxx
> > > >>抄送
> > > >>
> > > >>主题
> > > >>Re: [Sipping] About offeranswer draft:
> > > >>
> > > >>Hi Gao,
> > > >>
> > > >>Considering a BCP recommendation in this case,
> > > >>
> > > >>>When UAC receives the different SDP in a reliable response from
> > > >>>the prior one in a non-reliable response, UAC may ...
> > > >>>1. terminate the session.
> > > >>>2. keep using the SDP in a non-reliable response.
> > > >>>3. change to the SDP in a reliable response.
> > > >>
> > > >>and,
> > > >>4. In case 2 or 3, it is recommended that the UAC confirms the current
> > > >> offer-answer status using a reINVITE or an UPDATE request.
> > > >>
> > > >>However I think "may" is adequate in case 3.
> > > >>
> > > >>Regards,
> > > >>Shinji
> > > >>
> > > >>gao.yang2@xxxxxxxxxx
> > > >>Fri, 9 Apr 2010 11:44:34 +0800
> > > >>>Hi,
> > > >>>
> > > >>>Yes, considering implementation, I also find the three ways,
> > especially
> > > >>>for the last two ways.
> > > >>>
> > > >>>My original thought is make clarification on the third one("3.
> > change to
> > > >>>the SDP in a reliable response"), by RFC3264's rule.
> > > >>>
> > > >>>In fact, I think by rules, the UAC should modify the session as it
> > is the
> > > >>>lawful answer. Using early media by the SDP prior to the lawful
> > answer is
> > > >>>something outside of the lawful rules(Reliably way of using
> > earlymedia is
> > > >>>Answer in 100rel).
> > > >>>
> > > >>>So, I think using or just discarding the SDP prior to the lawful
> > answer is
> > > >>>something depends on implementation. While "change to the SDP in a
> > > >>>reliable response" should be normative.
> > > >>>
> > > >>>Thanks,
> > > >>>
> > > >>>Gao
> > > >>>
> > > >>>OKUMURA Shinji <shinji.okumura@xxxxxxxxxxxx>
> > > >>>发件人: sipping-bounces@xxxxxxxx
> > > >>>2010-04-09 10:13
> > > >>>
> > > >>>收件人
> > > >>>sipping@xxxxxxxx
> > > >>>抄送
> > > >>>
> > > >>>主题
> > > >>>Re: [Sipping] About offeranswer draft:
> > > >>>
> > > >>>Hi Gao,
> > > >>>
> > > >>>I have no doubt that the different SDP in non-reliable response
> > > >>>violates current regulations.
> > > >>>
> > > >>>The behaviour of UAC is an implementation issue, I think.
> > > >>>When UAS receives the different SDP in a reliable response from
> > > >>>the prior one in a non-reliable response, UAS may ...
> > > >>>1. terminate the session.
> > > >>>2. keep using the SDP in a non-reliable response.
> > > >>>3. change to the SDP in a reliable response.
> > > >>>
> > > >>>It is not clear, but it is not a regular case.
> > > >>>
> > > >>>Regards,
> > > >>>Shinji
> > > >>>
> > > >>>gao.yang2@xxxxxxxxxx
> > > >>>Wed, 7 Apr 2010 11:14:07 +0800
> > > >>>>Hi Paul,
> > > >>>>
> > > >>>>While considering one problem in our production's interoperability
> > > >>>>testing, I re-read some parts of offeranswer draft and find
> > something
> > > >>>>might be deserving discussion.
> > > >>>>
> > > >>>>//begin of text(part):
> > > >>>> For example, in Figure 1, only the SDP in F6 is the answer.
> > The SDP
> > > >>>> in the non-reliable response (F2) is the preview of the answer and
> > > >>>> must be the same as the answer in F6. Receiving F2, the UAC
> > should
> > > >>>> act as if it receives the answer.
> > > >>>>//end of text(part)
> > > >>>>
> > > >>>>[Gao] In fact, UAS sending SDP in non-reliable response is for
> > potential
> > > >>>>early media usage. Considering some UAS may have different
> > address for
> > > >>>>early media channel and the final session, some UAS may send
> > different
> > > >>>>SDP(compare with the answer) in non-reliable response. And I
> > really found
> > > >>>>such equipment inside and outside of ZTE. And considering UAC,
> > Ithink we
> > > >>>>should allow the UAC ignore the SDP in non-reliable response,
> > while some
> > > >>>>UAC really do not handle any SDP which is not offer or answer.
> > > >>>>
> > > >>>>But the permissibility of the degree of the difference might be
> > delicate.
> > > >>>>If the non-answer SDP just has different ip address or port, it
> > seams OK.
> > > >>>>If the non-answer SDP has different media streams, it would be
> > hard to
> > > >>>>handle for UAC.
> > > >>>>
> > > >>>>
> > > >>>>And I re-read correlative part of RFC3261. I don't know that whether
> > > >>>>allowing different SDP(compare with the answer) in non-reliable
> > response
> > > >>>>is violation/correction of current text or not.
> > > >>>>
> > > >>>>//correlative part of RFC3261
> > > >>>> o If the initial offer is in an INVITE, the answer MUST be
> > in a
> > > >>>> reliable non-failure message from UAS back to UAC which is
> > > >>>> correlated to that INVITE. For this specification, that is
> > > >>>> only the final 2xx response to that INVITE. That same exact
> > > >>>> answer MAY also be placed in any provisional responses sent
> > > >>>> prior to the answer. The UAC MUST treat the first session
> > > >>>> description it receives as the answer, and MUST ignore any
> > > >>>> session descriptions in subsequent responses to the initial
> > > >>>> INVITE.
> > > >>>>
> > > >>>>Thanks,
> > > >>>>
> > > >>>>Gao
> > > >
> > > >_______________________________________________
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