[Sipping] Reconciling O/A rollback with dialog state rollback

[Robert Sparks <rjsparks at nostrum.com>]

During the SIPPING meeting this morning, I noted discomfort around  
potential conflicts from choosing one path for rolling back offer/ 
answer and rolling back dialog state on failed re-INVITEs.

I found the diagram we looked at in Montreal describing the problem  
with dialog state - here's a copy.

Christer's proposal 2 for the offer/answer situation is to stay with  
whatever offer/answer exchange completed successfully last (perhaps in  
the INVITE/183 below). Would it also be acceptable to stay with  
whatever remote Target was successfully set last? In the diagram below  
that means the NOTIFY in question would use A'.

At the moment, I can't think of why drawing the line in the sand at  
that place would be any worse than rolling back to the beginning of  
the INVITE transaction. Further, in the case of multiple usages, it's  
arguably better - if I have a successful reSUBSCRIBE in a usage  
sharing a dialog with a pending INVITE transaction, it feels wrong  
that the whatever target that reSUBSCRIBE might have set be rolled  
back by the INVITEs failure.

So, unless someone comes up with an obvious problem with this, then  
I'm ok going with Christer's proposal 2 for offer/answer and propose  
we do a correction for 3261 clarifying the treatment of remoteTarget  
on failed target refresh transactions addressing having overlapping  
transactions that succeed.

RjS

Attachment: sipping66-sparks-dialogusage.ppt.pdf
Description: Adobe PDF document

_______________________________________________
Sipping mailing list  https://www.ietf.org/mailman/listinfo/sipping
This list is for NEW development of the application of SIP
Use sip-implementors at cs.columbia.edu for questions on current sip
Use sip at ietf.org for new developments of core SIP