RE: [Sipping] Question on ReInvite procedures
Jonathan Rosenberg <jdrosen@dynamicsoft.com> Fri, 31 August 2001 03:53 UTC
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From: Jonathan Rosenberg <jdrosen@dynamicsoft.com>
To: 'Bert Culpepper' <bert.culpepper@intervoice-brite.com>, 'Hemant Agrawal' <hagrawal@telverse.com>, sipping@ietf.org
Subject: RE: [Sipping] Question on ReInvite procedures
Date: Thu, 30 Aug 2001 23:41:17 -0400
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> -----Original Message----- > From: Bert Culpepper [mailto:bert.culpepper@intervoice-brite.com] > Sent: Wednesday, August 22, 2001 5:15 PM > To: 'Hemant Agrawal'; sipping@ietf.org > Subject: RE: [Sipping] Question on ReInvite procedures > > > This kind of behavior is discussed in draft-rosenberg-sip-3pcc-01.txt. > It STRONGLY RECOMMENDs that UAs do not change their address and port > assignments in responses to re-INVITEs when asked to change > the address > and port they send media to. Actually, I do not think that the 3pcc document actually makes this recommendation, nor does bis, as I can recall. At one time, we discussed this as a strong recommendation in order to enable flow 2 from 3pcc. But, since it was generally agreed that you can't REQUIRE this behavior, especially when codec changes are involved, so flow 2 was not recommended. Neither of the two recommended flows rely on a UA maintaining the same SDP. Thus, while keeping the same address/port is probably a good idea, it is not needed for the recommended 3pcc flows. > RFC2543bis touches > on this in > appendix B but for a little different scenario. That is, > re-INVITE w/o > SDP, 200 with "previous SDP" (offer), and ACK with SDP > (answer). In the > first paragraph of section B.4 it states "... the offerer SHOULD offer > the same SDP it provided previously if it has no reason to change > anything." Well, this scenario is a bit different. Here, we are talking about a "triggered offer", where the UA is prodded into making an offer. In the case above, we are talking about an answer to an offered SDP. > It's up to implementers to comply with the recommendation > above for 3pcc to work. No, as I said, flow 2 is not recommended so you don't need this behavior. What is needed is the ability to accept INVITE w/o SDP, since this is the cornerstone of flows 1 and 3. When people ask me what is the most important, yet most frequently overlooked SIP capability to implement in a UA, it is that. -Jonathan R. --- Jonathan D. Rosenberg, Ph.D. 72 Eagle Rock Ave. Chief Scientist First Floor dynamicsoft East Hanover, NJ 07936 jdrosen@dynamicsoft.com FAX: (973) 952-5050 http://www.jdrosen.net PHONE: (973) 952-5000 http://www.dynamicsoft.com _______________________________________________ Sipping mailing list http://www1.ietf.org/mailman/listinfo/sipping This list is for NEW development of the application of SIP Use sip-implementors@cs.columbia.edu for questions on current sip Use sip@ietf.org for new developments of core SIP
- [Sipping] Question on ReInvite procedures Hemant Agrawal
- RE: [Sipping] Question on ReInvite procedures Bert Culpepper
- RE: [Sipping] Question on ReInvite procedures Brett Tate
- RE: [Sipping] Question on ReInvite procedures Jonathan Rosenberg
- RE: [Sipping] Question on ReInvite procedures Bert Culpepper