Re: [reSIProcate] DUM: Detecting Stale Re-Invites

[Byron Campen <bcampen@xxxxxxxxxxxx>]

        We won't get a 408 if the other end sends a provisional.

Best regards,
Byron Campen

> I may have misunderstood but why do we need a timer at all? Can't we
> just tear down the dialog with a BYE if we receive a 408 to the
> reINVITE?
>
> On 10/1/07, Scott Godin <slgodin@xxxxxxxxxxxx> wrote:
> > DUM currently has a mechanism to detect stale initial client invite
> > sessions, ie. those that receive a provisional response, but never  
> > a final
> > response.  We do this by starting a Stale call timer and tearing  
> > the usage
> > down if it fires.
> >
> >
> >
> > We do NOT have a similar mechanism for re-INVITES
> >
> >
> >
> > Consider the following scenario:
> >
> > -          We have an established Invite Session
> >
> > -          The remote UA goes "offline"
> >
> > -          DUM sends a re-INVITE request (either user initiated or  
> > session
> > timer refresh)
> >
> > -          The stack receives a 100 Trying from the first hop  
> > proxy – so we
> > will never see a 408 generated to DUM.
> >
> > -          DUM is now stuck in the SentReInvite state.
> >
> > -          Calling end(), causes a transition into the  
> > WaitingToTerminate
> > state, where we will wait forever for the final response to the  
> > reInvite
> > request.
> >
> > -          Apparently calling end() a second time, will cleanup  
> > the usage,
> > but this means the application must be responsible for this, and  
> > it is not
> > very clean
> >
> >
> >
> > Note: mid-dialog non-INVITE transitions will always see a 408 if  
> > no final
> > response is seen.
> >
> >
> >
> > I propose we add a ReInviteStaleCall timer to the DUM state  
> > machine in order
> > to be able recover better from this situation.  The timer can be  
> > relatively
> > short (say 32seconds) since this is a re-INVITE and a final  
> > response is
> > expected to be fast.
> >
> > 1.        Timer is started when we send a re-INVITE.
> >
> > 2.       Time is effectively stopped when we get a final response  
> > to the
> > re-INVITE.
> >
> > 3.       If timer fires in the SentReInvite or WaitingToTerminate  
> > states,
> > then we continue to send a BYE and tear down the usage.
> >
> >
> >
> > Make sense?
> >
> >
> >
> > Scott
> >
> >
> >
> >
> > _______________________________________________
> > resiprocate-devel mailing list
> > resiprocate-devel@xxxxxxxxxxxxxxx
> > https://list.resiprocate.org/mailman/listinfo/resiprocate-devel
> _______________________________________________
> resiprocate-devel mailing list
> resiprocate-devel@xxxxxxxxxxxxxxx
> https://list.resiprocate.org/mailman/listinfo/resiprocate-devel

Attachment: smime.p7s
Description: S/MIME cryptographic signature