Subject: [Sipping] WGLC for draft-ietf-sipping-reason-header-for-preemption-00.txt

From: [email-masked]
Date: Sun, 29 Feb 2004 21:31:58 EST

Comments on WGLC for reason header.
Sorry that I didn't review this version and comment by Feb 29. I had thought 
that this issue was resolved after our e-mail discussion some time ago.

The draft defines 2 reasons for preemption (access and network) and provides 
an indicatation to the UA of which one occurred.

The requirment for Assured Service (otherwise known as MLPP) is that the 
preempted party is not allowed to know why the preemption occurred. This would 
have the result of telling the person something they are not supposed to know, 
that the party they were talking to got a more important call.

Presuming that some network may want to notify the UA of the reason, this 
needs to be corrected by adding a third reason in Section 6.0 as follows (also in 
Section 4.0 as appropriate):

    In instances where this namespace is used to indicate preemption, 
    but it is not desirable to notify the UA at the end of the preempted 
    session the reason for the preemption, the following syntax shall be used:

       Reason: preemption ; cause=3 ;text="Unspecified_Preemption"

       This case may be used in place of either the UA_Preemption in 
       Section 4.1 or the RSVP_Preemption in Section 4.2.

If neccesary, a new Section 4.3 could be added to explain this 3rd value, 
that is, why/when it would be used. This would be one paragraph, no diagram 
needed. I'll provide it if needed.

Mike Pierce

---

From: "James M. Polk" <[email-masked]>
Date: Sun, 29 Feb 2004 22:38:03 -0600

comments in-line

At 09:31 PM 2/29/2004 -0500, [email-masked] wrote:
>Sorry that I didn't review this version and comment by Feb 29. I had 
>thought that this issue was resolved after our e-mail discussion some time 
>ago.
>
>The draft defines 2 reasons for preemption (access and network) and 
>provides an indicatation to the UA of which one occurred.
>
>preempted party is not allowed to know why the preemption occurred. This 
>would have the result of telling the person

how exactly is informing the UA translate into telling the user why 
something has happened always (which is the way I read your question)?

Communicating in the BYE "why" a session was preempted to all the SIP 
entities (including the remote UA) is a network mgmt requirement (SIP layer 
synchronization) and a function at least some want knowledge of, perhaps 
not the DSN at the moment.

>something they are not supposed to know, that the party they were talking 
>to got a more important call.
>
>needs to be corrected by adding a third reason in Section 6.0 as follows 
>(also in Section 4.0 as appropriate):

I believe this can be accomplished by using the following:

         Reason: Q.850; cause=8

which is a generic preemption indication for the circuit world

if others disagree - adding this 3rd "reason" is fine with me

>that is, why/when it would be used. This would be one paragraph, no 
>diagram needed. I'll provide it if needed.
>
>Mike Pierce

cheers,
James

                                *******************
                 Truth is not to be argued... it is to be presented

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