Subject: RE: [Sip] Outbound: Questions on reg-id

From: "Christer Holmberg \(JO/LMF\)" <[email-masked]>
Date: Wed, 5 Apr 2006 11:05:22 +0200

Hi Fredrik,

If you agree on what I say, I see no harm in documenting it. I think it
will clarify things, and HELP interoperability :) I've been to a number
of SIPits (and bake-offs before that) myself, and I believe many of the
problems that have occured could have been avoided with a little better
explanation/clarification in the documents.

RFC 3261 also says that the same Call-Id value should be used for all
registrations sent from a UA. I don't think it matters if the same
Call-Id is used for different reg-ids or not, but in order to avoid
questions in the future I see no harm in putting down a few words about
it.

Regards,

Christer

-----Original Message-----
From: Fredrik Thulin [mailto:[email-masked]] 
Sent: 5. huhtikuuta 2006 11:58
To: Christer Holmberg (JO/LMF)
Cc: [email-masked]
Subject: Re: [Sip] Outbound: Questions on reg-id

On Wednesday 05 April 2006 09:50, Christer Holmberg (JO/LMF) wrote:
> Hi Fredrik,
>
> I wonder if it would be good to combine the checking of the reg-id and

> Call-ID then.
>
> Because, even if the UA does NOT reboot, it is still going to send 
> periodical registration refreshes, without updating the flow 
> characteristics (source port etc).
>
> So, if the reg-id AND Call-Id are identical from the previous register

> the receiver would assume this is just a refresh.
>
> But, if the reg-id is identical, but the Call-Id is NOT, from the 
> previous register (the Call-Id must change after the reboot, in order 
> not cause problems with the Cseq check by the receiver) the receiver 
> would assume that a flow has been "replaced" (e.g. due to a UA 
> reboot).

I think these are issues you have to deal with when implementing
Outbound in a Registrar (something I have done), but not something that
needs to be explained further in the standard. If Outbound _replaced_
RFC3261 #10.3 then it would have to be spelled out, but it doesn't - it
just extends it.

In my implementation I didn't touch the RFC3261 10.3 processing. I just
added functionality to remove any contacts in the location database
whose instance-id and reg-id matched the contact (from a REGISTER)
currently being processed to the code that already removed any bindings
in the location database for the current AOR whose URI matched the
contact being processed.

After SIPIT I hope to be able to tell you if this works in practice and
not only in theory (theory plus test cases).

/Fredrik

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---

From: Fredrik Thulin <[email-masked]>
Date: Wed, 5 Apr 2006 11:38:01 +0200

On Wednesday 05 April 2006 11:05, Christer Holmberg (JO/LMF) wrote:
> Hi Fredrik,
>
> If you agree on what I say, I see no harm in documenting it. 

What _are_ you saying? What is it that you want to document?

I must be misunderstanding you somewhere, because it sounds to me like 
you want the Outbound specification to say that you must not only do 
REGISTER processing as per the Outbound specification, but also 
according to RFC3261 #10.3. I think that is obvious and I think it 
makes no sense to litter Outbound with such references.

/Fredrik