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

[ding.xuexin at zte.com.cn]

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:bob at example.com
   Route: <sip:xx at example.com;lr>

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

   INVITE sip:xx at example.com
   Route: <sip:bob at example.com>

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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