答复: Re: Hi Paul //About draft- ietf-sipping-sip-offeranswer-11

I also agree with Keith that normative correction should be in a (new) 
standard track text aimed for RFC3264. So, the key is whether my 
suggestion is BCP level or not, Paul?

But I still think my suggestion is BCP level, not normative. The reason is 
that it is not intend to exclude the behavior not obeying the suggestion. 
UAS introducing new media types without user's permission can still make 
the call OK.

Thanks,

Gao

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Paul Kyzivat <[email protected]> 
2010-03-03 07:40

收件人
"DRAGE, Keith (Keith)" <[email protected]>
抄送
"[email protected]" <[email protected]>, sipping <[email protected]>
主题
Re: [Sipping] Hi Paul //About draft-ietf-sipping-sip-offeranswer-11






I agree that this sort of thing is best practice suggestion and should
not contain normative language.

                 Thanks,
                 Paul

DRAGE, Keith (Keith) wrote:
> offeranswer was the informational document that examined poor usage of 
> existing normative specification text in RFC 3264. It is not intended to 

> carry nomative information in its own right.
> 
> If you feel normative language is needed, then you need a document that 
> updates RFC 3264, either as a separate document or one that replaces it. 

> We have talked about that in the past as part of the SIP work, shortly 
> before the SIP group got closed.
> 
> regards
> 
> Keith
> 
> ------------------------------------------------------------------------
>     *From:* [email protected] [mailto:[email protected]]
>     *On Behalf Of *[email protected]
>     *Sent:* Tuesday, March 02, 2010 7:02 AM
>     *To:* Paul Kyzivat
>     *Cc:* sipping
>     *Subject:* Re: [Sipping] Hi Paul //About
>     draft-ietf-sipping-sip-offeranswer-11
> 
> 
>     Hi Paul,
> 
>     I just feel adding some BCP level description (something like the
>     description below) would let people do system design and implement
>     clearly.
> 
>     "When recv Re-INVITE without Offer, UAS SHOULD avoid of introducing
>     new media types without user's permission or local policy
>     configuration, that is its current using media types."
> 
>     Thanks,
> 
>     Gao
> 
>     ===================================
>     Zip    : 210012
>     Tel    : 87211
>     Tel2   :(+86)-025-52877211
>     e_mail : [email protected]
>     ===================================
>     ----- 转发人 GaoYang140197/user/zte_ltd 时间 2010-03-02 14:56 -----
>     *GaoYang140197/user/zte_ltd*
> 
>     2010-03-01 13:44
> 
> 
>     收件人
>                Paul Kyzivat <[email protected]>
>     抄送
>                sipping <[email protected]>
>     主题
>                Re: Hi Paul  //About 
draft-ietf-sipping-sip-offeranswer-11链接
>     <
Notes://NJMAIL01/48257169002DF8EE/DABA975B9FB113EB852564B5001283EA/A95B47510FB03B93482576D6004E7AE9
>
> 
> 
> 
> 
> 
> 
> 
> 
>     As you have a new version, I think including sipping would be better 
:)
> 
>     Thanks for your agreement at this point.
> 
>     But as RFC3261's words of "willings" is not as clear as guidance for
>     system design and implement, I think some BCP level description
>     vcould be better.
> 
>     Thanks,
> 
>     Gao
> 
>     ===================================
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>     Tel    : 87211
>     Tel2   :(+86)-025-52877211
>     e_mail : [email protected]
>     ===================================
> 
> 
>     *Paul Kyzivat <[email protected]>*
> 
>     2010-02-26 22:17
> 
> 
>     收件人
>                [email protected]
>     抄送
>                sipping <[email protected]>
>     主题
>                Re: Hi Paul  //About 
draft-ietf-sipping-sip-offeranswer-11
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
>     [email protected] wrote:
>      >
>      > I just find a potential problem of
>      > draft-ietf-sipping-sip-offeranswer-11. I am not sure will you
>     want have
>      > a new version, so I send this discussion offline.
> 
>     I am working on another version. I am including sipping in my 
response
>     so others have the opportunity to comment. (I trust that is ok.)
> 
>      > Section 5.2.5. of draft-ietf-sipping-sip-offeranswer-11:
>      > When the new offer is sent in response to an offerless 
(re)INVITE,
>      >    *all codecs supported by the UA are to be included*, not just
>     the ones
>      >    that were negotiated by previous offer/answer exchanges.  *The
>     same is*
>      > *   true for media types* - so if UA A initially offered audio
>     and video
>      >    to UA B, and they end up with only audio, and UA B sends an
>     offerless
>      >    (re)INVITE to UA A, A's resulting offer should re- attempt
>     video, by
>      >    reusing the zeroed m-line used previously.
>      >
>      >
>      > While Re-INVITE without Offer:
>      > For codecs, I think the UAS should include as many codecs that
>     the UA is
>      > willing(section 14.2 of RFC3261) to support. I think we should
>     let the
>      > UA has the right to decide which codecs can be use or not for 
this
>      > current call. At the same time, the UAS should be with
>     responsibility
>      > for failure of session if it cut down the number of codecs. UAS's
>      > willing of codecs can be implemented as local policy or some
>     other forms
>      > of configuration.
> 
>     Yes, this just requires minor tweak to wording.
>     Its consistent with the recommendations on sendonly/...
> 
>      > For media types, it is almost the same as codecs, about UA's
>     willing.
>      > But I think we should emphasize on avoiding of introducing new 
media
>      > types without user's permission, such as just introducing new 
media
>      > types  by equipment or software. Beacause I have met such 
charging
>      > arguement from users in some operating telecom-network.(If you
>     want the
>      > detail of the charging arguement, I'd like to share it with you).
>      > So, if there is no indication of permission of introducing new 
media
>      > types from the end user, UAS should just include current using 
media
>      > types. And if the other side(user of UAC) want to add media
>     types, it
>      > can using another new Offer.
> 
>     I get your point and agree. Its the same concept - include 
everything
>     the UA would be willing to use, not just that which it thinks the 
peer
>     wants to use.
> 
>                     Thanks,
>                     Paul
> 
>      > Thanks,
>      >
>      > Gao
>      >
>      > Section 14.2 of RFC3261:
>      > A UAS providing an offer in a 2xx (because the INVITE did not 
contain
>      >    an offer) SHOULD construct the offer as if the UAS were making 
a
>      >    brand new call, subject to the constraints of sending an offer
>     that
>      >    updates an existing session, as described in [13] in the case
>     of SDP.
>      >    Specifically, this means that it SHOULD include as many media
>     formats
>      >    and media types that the UA *is willing to support*.  The UAS 
MUST
>      >    ensure that the session description overlaps with its previous
>      >    session description in media formats, transports, or other
>     parameters
>      >    that require support from the peer.  This is to avoid the need 
for
>      >    the peer to reject the session description. 
>      >
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>      > Tel    : 87211
>      > Tel2   :(+86)-025-52877211
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>      >
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