Re: [sipcore] Why doesn't 4244bis cover Marianne's use-case?

Paul Kyzivat <pkyzivat@cisco.com> Fri, 19 November 2010 18:15 UTC

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Date: Fri, 19 Nov 2010 13:16:35 -0500
From: Paul Kyzivat <pkyzivat@cisco.com>
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Subject: Re: [sipcore] Why doesn't 4244bis cover Marianne's use-case?
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I'm inclined to agree that this draft 
(draft-mohali-sipcore-reason-extension-application, not 
draft-mohali-diversion-history-info) *ought* to be orthogonal to 
4244bis, and "just work" with it.

BUT, in reality I'm not convinced that this is so. The following is from 
4244bis:

    For retargets that are the result of an explicit SIP response, a
    Reason MUST be associated with the hi-targeted-to-uri.  If the SIP
    response does not include a Reason header (see [RFC3326]), the SIP
    Response Code that triggered the retargeting MUST be included as the
    Reason associated with the hi-targeted-to-uri that has been
    retargeted.  If the response contains a Reason header for a protocol
    that is not SIP (e.g., Q.850), it MUST be captured as an additional
    Reason associated with the hi-targeted-to-uri that has been
    retargeted, along with the SIP Response Code.  If the Reason header
    is a SIP reason, then it MUST be used as the Reason associated with
    the hi-targeted-to-uri rather than the SIP response code.

Note that the above is limited to "retargets that are the result of an 
explicit SIP response". But when I look at the call flows in the draft, 
none of the retargets are the result of a sip response. Rather, they are 
spontaneous retargets due to server logic. 4244bis does not cover using 
the Reason header in H-I entries for this purpose.

	Thanks,
	Paul

On 11/19/2010 11:42 AM, Worley, Dale R (Dale) wrote:
> ________________________________________
> From: sipcore-bounces@ietf.org [sipcore-bounces@ietf.org] On Behalf Of Hadriel Kaplan [HKaplan@acmepacket.com]
>
> It was unfortunate that we ran out of time in sipcore to talk about Marianne's draft, because I think it's a kind of litmus test of rfc4244bis.  Or else I think I must be missing something very basic. (easily the case)
> _______________________________________________
>
> As others have said in other terms,  draft-mohali-diversion-history-info is orthogonal to 4244bis.  draft-mohali provides additional Reason values that provide more detailed information on why a call was routed as it was.  Those Reason values will be recorded in H-I according to 4244bis.  In a sense, draft-mohali *is* a litmus test of 4244bis, because without H-I, the value of the new Reason values would be dramatically reduced.  But since the two are orthogonal, draft-mohali needs to be specified, but it can be specified separately.
>
> Dale
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