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:* sipping-bounces@xxxxxxxx [mailto:sipping-bounces@xxxxxxxx] > *On Behalf Of *gao.yang2@xxxxxxxxxx > *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 : gao.yang2@xxxxxxxxxx > =================================== > ----- 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 <pkyzivat@xxxxxxxxx> > 抄送 > sipping <sipping@xxxxxxxx> > 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 > > =================================== > Zip : 210012 > Tel : 87211 > Tel2 :(+86)-025-52877211 > e_mail : gao.yang2@xxxxxxxxxx > =================================== > > > *Paul Kyzivat <pkyzivat@xxxxxxxxx>* > > 2010-02-26 22:17 > > > 收件人 > gao.yang2@xxxxxxxxxx > 抄送 > sipping <sipping@xxxxxxxx> > 主题 > Re: Hi Paul //About draft-ietf-sipping-sip-offeranswer-11 > > > > > > > > > > > gao.yang2@xxxxxxxxxx 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. > > > > =================================== > > Zip : 210012 > > Tel : 87211 > > Tel2 :(+86)-025-52877211 > > e_mail : gao.yang2@xxxxxxxxxx > > =================================== > > > > -------------------------------------------------------- > > ZTE Information Security Notice: The information contained in > this mail is solely property of the sender's organization. This mail > communication is confidential. Recipients named above are obligated > to maintain secrecy and are not permitted to disclose the contents > of this communication to others. > > This email and any files transmitted with it are confidential and > intended solely for the use of the individual or entity to whom they > are addressed. If you have received this email in error please > notify the originator of the message. 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