Subject: [Sipping] New ID on Reader Header for Preemption

From: "James M. Polk" <[email-masked]>
Date: Tue, 14 Oct 2003 10:03:25 -0500

I've just posted this new ID that I believe some on this list will find of 
interest

This document proposes an extension to the Session Initiation Protocol 
(SIP) Reason Header to include in a BYE Method Request as a result of a 
session preemption event either at a user agent (UA), or somewhere in the 
network using RSVP.  This document does not attempt to address routers 
failing in the packet path; but a deliberate event of tearing down a flow 
between UAs.

>         Title           : Extending the Session Initiation Protocol Reason
>                           Header to account for Preemption Events
>         Author(s)       : J. Polk
>         Filename        : 
> draft-polk-sipping-reason-header-for-preemption-00.txt
>         Pages           : 14
>         Date            : 2003-10-10
>
>
>A URL for this Internet-Draft is:
>http://www.ietf.org/internet-drafts/draft-polk-sipping-reason-header-for-preemption-00.txt
>
><ftp://ftp.ietf.org/internet-drafts/draft-polk-sipping-reason-header-for-preemption-00.txt>

cheers,
James

                                *******************
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From: Cullen Jennings <[email-masked]>
Date: Sat, 18 Oct 2003 21:50:52 -0700

IP phone A is in a call and it gets presented - the call will get torn down.
Does A do something different because the call was torn down because of
preemption? 

Is it just so we can tell the user of phone A something useful about why
their call ended?

Cullen

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From: "David R. Oran" <[email-masked]>
Date: Sun, 19 Oct 2003 09:11:30 -0400

--On Saturday, October 18, 2003 9:50 PM -0700 Cullen Jennings 
<[email-masked]> wrote:

>
> IP phone A is in a call and it gets presented - the call will get torn
> down. Does A do something different because the call was torn down
> because of preemption?
>
Possibly run a longer retry timer if the phone is programmed to try to 
reestablish calls automatically.

> Is it just so we can tell the user of phone A something useful about why
Mostly. It may also have use in statistics so that these calls don't get 
lumped in with stats used to compute MTBF and MTTR.

> Cullen

------------------------
David R. Oran
Cisco Systems
7 Ladyslipper Lane
Acton, MA 01720
Office: +1 978 264 2048
VoIP: +1 408 571 4576
Email: [email-masked]

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From: "James M. Polk" <[email-masked]>
Date: Sun, 19 Oct 2003 12:58:25 -0500

>lumped in with stats used to compute MTBF and MTTR.

SIP element synchronization (including Servers) of a specific event is one 
aspect that is important (this would be just as Dave stated - for 
statistics or accounting).

One other one is that UAs that receive this BYE with this Reason value will 
(in some networks) need to play either a specific tone or announcement to 
that user which is appropriate to that event.

If A_B are in a session when C signals to B to preempt any session it is 
currently on, *something* has to tell A it is no longer in the session, a 
BYE is appropriate. But, this is not a normal end of session event, it is 
preemption. If that event needs to cause UA A to play a unique preemption 
tone (or play an announcement), it needs some indication in the BYE to do 
such an action. My proposal for a new Reason value is this indication.

Is this not the general concept behind the Reason Header (to provide more 
information)?

comments

cheers,
James

                                *******************