[Serusers] Routing with ser / Problems with linphone

Jiri Kuthan jiri at iptel.org
Sat Feb 15 00:18:59 CET 2003

/* digging through the archives to make sure I haven't missed anything
   while I was off-line last weeks ...

I actually think that is a backwards compatibility issue in SIP.
Loose-routing works correctly if sender knows whether the next-hop
is loose or strict router. That is a correct assumption as long as
the routing information collected automatically in record-route 
tells you that. If you use pre-configured Route along with an 
outbound proxy, you configure this strict/loose on your own and
you need to get it right. Hence, when you configure loose routing 
for use with a strict outbound router, things will fail.

Anyway, with lr support in next ser release, it should not matter
any more. We've had the same issue with kphone previouly, it works
since an option has been introduce to enforce use of strict routing.
see http://www.ietf.org/mail-archive/working-groups/sipping/current/msg03451.html


At 11:18 AM 2/5/2003, Klaus Darilion wrote:
>I've installed ser (sip:obelix.ict.tuwien.ac.at) und want'ed to use it
>with linphone, so I configured linphone to use ser as outbound proxy and
>registrar. The registration works fine but not the INVITEs. ser answers
>to an INVITE from linphone with a 404 Not Found and I found out that the
>problem is the "Route" header in the INVITE from linphone.
>Route: <sip:obelix.ict.tuwien.ac.at;lr>
>When I remove the header from the invite and send it manually (sipsak)
>the ser proxy accepts the invite and forwards it. I think ser reacts
>wrong because if an RFC3261 proxy gets an request with a route header
>which points to itself it should remove the header and forward the
>Than I tried the same with an different proxy in the route header:
>Route: <sip:iptel.org;lr>
>Now, my ser proxy (sip:obelix.ict.tuwien.ac.at) accepts the request and
>forwards it to iptel.org, but it rewrites the invite to:
>INVITE sip:iptel.org;lr SIP/2.0
>Thats what an RFC2543 proxy would do, but not an RFC3261 proxy, which
>only is allowed to do that if the route header has no "lr" parameter or
>if he is responsible for the domain in the request URI. If there is an
>"lr" parameter the proxy must not change the request URI.
>If I'm wrong please let me know.
>I use ser 0.8.10 with the standard config file and linphone 0.9.1 &
>Serusers mailing list
>serusers at lists.iptel.org

Jiri Kuthan            http://iptel.org/~jiri/  

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