Subject: [Sip] two questions for route information preprocessing of initial INVITE with Route headers

From: [email-masked]
Date: Fri, 18 Sep 2009 13:46:39 +0800

Hi, all

I have two questions for route information preprocessing of initial INVITE
with Route headers

first question:

UA(or B2BUA) receives an initial INVITE with Route headers, assuming UA's
host is example.com

if the sip entity which sends the INVITE is a loose router, the INVITE may
be like this:

   INVITE sip:[email-masked]
   Route: <sip:[email-masked];lr>

if the sip entity which sends the INVITE is a strict router, the INVITE may
be like this:

   INVITE sip:[email-masked]
   Route: <sip:[email-masked]>

we cannot distinguish those two scenarioes because Requet-URIs in two
scenarioes are similar.
if we do route information preprocessing according RFC3261 section 16.4, we
will get two different
results. And there is no desciption for UA route information preprocessing
in RFC3261, RFC3261
section 16.4 just describes proxy behavior.

How to processing route information of initial INVITE with Route headers
for UA?

second question:

as RFC3261 section 16.4 descibed, proxy must check whether the request-uri
was placed by the
proxy previously. But the request-uri in initial INVITE must not be placed
by the proxy previously.

Is something wrong with RFC3261 section 16.4?

                                                                   Best
Regards

LionEagle

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---

From: "Scott Lawrence" <[email-masked]>
Date: Tue, 22 Sep 2009 12:33:10 -0400

> I have two questions for route information preprocessing of initial INVITE

These questions would be more appropriate on the sip-implementors
<[email-masked]> mailing list.

---

From: "Dale Worley" <[email-masked]>
Date: Wed, 30 Sep 2009 17:12:13 -0400

> How to processing route information of initial INVITE with Route headers

The first question is whether the element is prepared to act as a proxy
(as well as a UA).

If the element is not prepared to act as a proxy, it can't process the
request properly, as the semantics are "First send to <sip...>, and let
it send to <sip...>".  So it should either ignore the message or return
an error.

If the element is prepared to act as a proxy, it should process the
message as a proxy would.

Dale