Subject: [Sip] Question on Service Route Discovery Procedure during Registration

From: "Lu, Yang, VF-DE" <[email-masked]>
Date: Mon, 3 Apr 2006 14:09:43 +0200

Dear All

RFC 3261 Section 8.2.4 "Applying Extensions" says

"A UAS that wishes to apply some extension when generating the response
MUST NOT do so unless support for that extension is indicated in the
Supported header field in the request".

However, the Service Route discovery  procedure during Registration
described in RFC 3608 does not follow this as shown in the example in
Section 6.

Are there any reasons for that and for the fact that there is no need to
define an Option Tag for Service Route?

Regards

Yang Lu
Vodafone

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---

From: Dean Willis <[email-masked]>
Date: Wed, 5 Apr 2006 12:05:32 -0500

> define an Option Tag for Service Route?

I remember debating this at the time that RFC 3608 was being edited,  
but do not recall why we ended up with the text therein. Looking at  
it from the perspective of history, at the moment it appears that  
you're absolutely right and that RFC 3608 is inconsistent with RFC  
3261 in this respect.

I do recall that there was a decision to not provide an option-tag  
for Service-Route related to the extremely "optional" nature of the  
information conveyed by Service-Route, which is actually completely  
orthogonal to the operation of the REGISTER request itself. We didn't  
want the UAC to be able to "demand" a service-route. With some  
deployment experience behind us, I'm not sure that this was really an  
important issue.

Jonathan is very fond of saying that both RFC 3608 and RFC 3327 are  
"broken, or at best horribly underspecified". I've been planning to  
rev them once GRUU and the route-construction draft stabilize,  
although its also been proposed that the route-construction draft  
might actually replace both 3608 and 3327. In either case, we should  
address this issue at that time.

Question to the WG: Should we post an errata for RFC 3608 to the RFC  
Editor page discussing this?

--
Dean