Re: [sipcore] Reason as a parameter rather than an escaped header

Hadriel Kaplan <HKaplan@acmepacket.com> Thu, 25 November 2010 11:56 UTC

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From: Hadriel Kaplan <HKaplan@acmepacket.com>
To: Paul Kyzivat <pkyzivat@cisco.com>
Date: Thu, 25 Nov 2010 06:57:01 -0500
Thread-Topic: [sipcore] Reason as a parameter rather than an escaped header
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Cc: "Worley, Dale R \(Dale\)" <dworley@avaya.com>, "sipcore@ietf.org" <sipcore@ietf.org>
Subject: Re: [sipcore] Reason as a parameter rather than an escaped header
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On Nov 23, 2010, at 7:06 PM, Paul Kyzivat wrote:

> But my remaining concern is about the rules in 4244bis regarding how and 
> when Reason headers are included in the H-I entries. It still seems to 
> me that the text only talks about including them due to a response 
> having been received. Where is the language that discusses adding a 
> reason when retargeting is performed for some reason unrelated to a 
> response?
> 
> While I think one can argue that a server doing such retargeting can 
> imagine having sent the request to a virtual redirect server and then 
> processing the response from it, ISTM that would then call for adding 
> H-I entries for those steps.

Right, that's the main piece to figure out first.  We already agreed that 4244bis tells proxies to create H-I entries for internal retargeting decisions.  What's not clear is what internal H-I entries have to be created, and whether the embedded Reason header value of the *SIP* type can be used for such cases.

For example, suppose Alice called Bob, and proxy-1 internally diverts it to Charlie because it knows Bob is busy, *without* having to send the INVITE to Bob and getting a 486 response.

Is it legit for the H-I look like this:
History-Info: <sip:bob@example.com?Reason=SIP%3Bcause%3D486>;index=1
History-Info: <sip:charlie@example.com>;index=1.1;mp=1
History-Info: <sip:charlie@192.1.2.3>;index=1.1.1;rc=1.1

Or does it have to look like this:
History-Info: <sip:bob@example.com>;index=1
History-Info: <sip:bob@127.0.0.1?Reason=SIP%3Bcause%3D486>;index=1.1
History-Info: <sip:charlie@example.com>;index=1.2;mp=1
History-Info: <sip:charlie@192.1.2.3>;index=1.2.1;rc=1.2

Or does it have to do something like this:
History-Info: <sip:bob@example.com?Reason=Internal%3Bcause%3D486>;index=1
History-Info: <sip:charlie@example.com>;index=1.1;mp=1
History-Info: <sip:charlie@192.1.2.3>;index=1.1.1;rc=1.1

-hadriel