[sr-dev] Adding support for Kamailio adding Path header

Klaus Darilion klaus.mailinglists at pernau.at
Fri Aug 10 12:50:31 CEST 2012



On 08.08.2012 13:09, Iñaki Baz Castillo wrote:
> 2012/8/8 Klaus Darilion <klaus.mailinglists at pernau.at>:
>> Not exactly. I takes care of choosing the proper IP address (outgoing
>> interface) but does not add double-headers like RR does.
>
> I don't understand why. If we require double RR (in same cases as when
> there is transport bridging) then we also need double Path in the same
> cases. The registrar will send us (to kamailio) an initial request
> with Route header(s) mirroring the Path header(s) we added to the
> REGISTER, so we need double Path in the same cases in which we need
> double RR. Am I wrong?

I think so. Double RR is needed when multihoming is used:

client<---------ext-kamailio-int--------->registrar

The client needs to see "ext" as next hop whereas the registrar needs to 
see "int" as next hop during in-dialog requests

The "path" is only used by the registrar (as pre-loaded route set on 
out-of-dialog requests). Thus, as only the registrar uses the learned 
path, only the "int" IP address needs to be added to path.

regards
Klaus



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