Re: PRACK: Does non-200 response cease re-transmission ofreliable 18x?

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Well, since we technically allow it to carry SDP and pretty much anything, then a while series of 4xx could be triggered related to body handling issues I guess.  Technically it's supposed to be used like an ACK I think, so "carefully".  But even just with SDP it may, in theory, be too big to reach the UAS.  Or if a pidf-location body is added, for example.

It can also carry a Require/Proxy-Require header and be rejected due to that, not that I can think of why that would realistically ever be an issue for PRACK.

-hadriel

> -----Original Message-----
> From: sipping-bounces@xxxxxxxx [mailto:sipping-bounces@xxxxxxxx] On Behalf
> Of Hisham Khartabil
> Sent: Wednesday, April 01, 2009 10:15 PM
> To: Rockson Li (zhengyli)
> Cc: Paul Kyzivat (pkyzivat); sipping@xxxxxxxx; Christer Holmberg
> Subject: Re:  PRACK: Does non-200 response cease re-transmission
> ofreliable 18x?
> 
> We already know that one. I was asking if there are any others.
> 
> Hisham
> 
> 2009/4/2 Rockson Li (zhengyli) <zhengyli@xxxxxxxxx>:
> >
> >
> > -----Original Message-----
> > From: sipping-bounces@xxxxxxxx [mailto:sipping-bounces@xxxxxxxx] On
> Behalf Of Hisham Khartabil
> > Sent: Thursday, April 02, 2009 9:37 AM
> > To: Paul Kyzivat (pkyzivat)
> > Cc: sipping@xxxxxxxx; Christer Holmberg
> > Subject: Re:  PRACK: Does non-200 response cease re-
> transmission ofreliable 18x?
> >
> > That's a good scenario. Any others?
> >
> > The point of the PRACK is to indicate to the UAS that the 1xx it sent
> was received successfully. Unless its a 401 to the PRACK, I don't see any
> other reason why the UAS should continue retransmitting the 1xx if its
> sent a non 2xx reponse to a PRACK. The PRACK has served its purpose.
> >
> > Having said that, what other reasons would a UAS reject a PRACK?
> > [RL] authentication.
> > https://lists.cs.columbia.edu/pipermail/sip-implementors/2009-
> March/022095.html
> >
> > Hisham
> >
> > 2009/4/1 Paul Kyzivat <pkyzivat@xxxxxxxxx>:
> >>
> >>
> >> Christer Holmberg wrote:
> >>>
> >>> Hi,
> >>>
> >>> One of the PRACK related issues presented in SFO is whether a PRACK
> >>> non-200 response would cease re-transmission of the assoicated
> >>> reliable 18x response.
> >>>
> >>> Based on the mail discussions we've had I proposed that the non-200
> >>> response DOES NOT ceasee the re-transmission. However, some people
> >>> seemed to have an issue with that, so I was asked to "take it to the
> list".
> >>>
> >>> The main justification why a non-200 response would not cease the
> >>> re-transmission is because an intermediate may reject the PRACK, in
> >>> which case the UAS will never receive it (read: the UAS will continue
> >>> to re-transmit the reliable 18x). So, when the UAC receives the PRACK
> >>> non-200 response it should send a new PRACK, which hopefully will
> >>> reach the UAS and trigger a 200 response.
> >>>
> >>> So, anyone who does not agree with the justification aboive, and
> >>> thinks that a non-200 response DOES cease the re-transmission of the
> >>> associated reliable 18x response, please indicate so.
> >>
> >> I agree with Christer here. Another scenario where this would be
> >> important
> >> is:
> >>
> >> -> INVITE
> >> <- 180rel
> >> -> PRACK
> >> <- 401
> >>
> >> It this case it is essential to retry the PRACK with updated
> credentials.
> >> Certainly the UAS doesn't want to consider the 180 to have been
> >> acknowledged in this case, since it might have been from a MiTM.
> >>
> >> This could come about in the case of a reINVITE, where the nonce used
> >> in the original INVITE finally becomes stale by the time the PRACK is
> received.
> >>
> >>        Thanks,
> >>        Paul
> >> _______________________________________________
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> >> This list is for NEW development of the application of SIP Use
> >> sip-implementors@xxxxxxxxxxxxxxx for questions on current sip Use
> >> sip@xxxxxxxx for new developments of core SIP
> >>
> > _______________________________________________
> > Sipping mailing list  https://www.ietf.org/mailman/listinfo/sipping
> > This list is for NEW development of the application of SIP Use sip-
> implementors@xxxxxxxxxxxxxxx for questions on current sip Use sip@xxxxxxxx
> for new developments of core SIP
> >
> _______________________________________________
> Sipping mailing list  https://www.ietf.org/mailman/listinfo/sipping
> This list is for NEW development of the application of SIP
> Use sip-implementors@xxxxxxxxxxxxxxx for questions on current sip
> Use sip@xxxxxxxx for new developments of core SIP
_______________________________________________
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This list is for NEW development of the application of SIP
Use sip-implementors@xxxxxxxxxxxxxxx for questions on current sip
Use sip@xxxxxxxx for new developments of core SIP


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