Re: [sipcore] #38: How is the mapping of a GRUU into its UA Contact marked?

Mary Barnes <> Fri, 22 October 2010 18:53 UTC

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Date: Fri, 22 Oct 2010 13:54:36 -0500
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From: Mary Barnes <>
To: "Worley, Dale R (Dale)" <>
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Subject: Re: [sipcore] #38: How is the mapping of a GRUU into its UA Contact marked?
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Hi Dale,

Responses inline below [MB].


On Thu, Oct 21, 2010 at 3:08 PM, Worley, Dale R (Dale)
<> wrote:
> ________________________________________
> From: Mary Barnes []
> So, then it seems you are advocating we add an additional "gr" tag.
> However, wouldn't the absence of "mp" or "rc" for a GRUU indicate that
> the GRUU wasn't mapped.  I guess it is not harmful to add a unique tag
> for cases where a GRUU is used, but do you have a use case where this
> is relevant?
> ________________________________________
> I haven't thought through all the use cases.  I've just been assuming that the goal is for each conversion of one URI into another to describe the nature of the conversion.  I expect the case of a GRUU being converted into its registered contact to be frequent, and there is the possibility that in some situations GRUUs will be converted into URIs some other way.  So it seems to me to be reasonable that there is a tag meaning "the mapping of a GRUU into its registered contact".
[MB] The question Shida raised earlier was why would you need this tag
when you have the "gr" tag in the URI and you have the "rc" tag in the
History-Info entry.  The question to me is to whom does it matter that
it was a GRUU that was mapped to a registered contact.  There is a
gruu use case in the call flows describing this.  [/MB]

> Perhaps an explanation of the organizing principle of the set of tags would make clearer why some conversions have tags and others do not.
[MB] That might help. The reason there are just the two tags was
because those were the ones that came out of the use cases. We
originally had all entries tagged and the pushback was that the other
tags were not necessary (at least for the use cases envisioned). For
example, there was a "noop" for next hop forwarding, a "predetermined"
for things like the Request-URI containing a maddr, strict routing,
etc. and the "rc"s were divided into two categories - normal
registered contacts and registered aliases.   In the end, it was only
the "rc" and "mp" that seemed to be relevant for most applications,
although one could debate that the others might help with debug. [/MB]
> Dale