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Re: [reSIProcate] Routing of signalling via proxy - opinions?



Steven Coule wrote:


Using a prototype with the Radvision stack, the Asterisk was ignoring
the maddr parameter which should (in my belief of the theory at least)
cause calls from the Asterisk to be routed via my Proxy. It didn't work,
and the maddr parameter seemed to be deliberately ignored in the code -
it could be patched, but I'm looking for the most compatible solution of
inserting my monitoring/call control solution into a SIP environment.



I'm not sure if we can configure an outbound proxy for SIP phones
registered to the Asterisk - I didn't think this was the case but will
take another look.
I believe outbound proxy is only recently added to Asterisk or not fully implemented in some versions. Older versions didn't have this at all. You would have to look at the source code to determine how it decides which calls/SIP messages go through the outbound proxy. 




The Route header is worth a try. I noted in 3261 that the Record-Route
header is to be deliberately ignored if present in a REGISTER, but that
doesn't apply to a Route header.  I guess the key here is whether the
Asterisk (or other) server will store the Route present in the REGISTER
request and use it to route calls to the UA's via my Proxy.



You mention using a Route header embedded in the URI ... from reading
the specs, it looks like this could work.  The Path Extension RFC 3327
header also seems like another option to look into - from reading the
spec it perhaps looks most likely to work.



I'll take a look at repro and Asterisk to see whether the Path is
supported ... 


Thanks for your help ..


Steve



________________________________
From: Scott Godin [mailto:slgodin@xxxxxxxxxxxx] Sent: 16 March 2006 14:59 
To: Steven Coule; resiprocate-devel@xxxxxxxxxxxxxxxxxxx
Subject: RE: [reSIProcate] Routing of signalling via proxy - opinions?



Record-route will only help for messages that go through your proxy - if
the INVITE is not even hitting your proxy, then you will need some other
mechanism to tell Asterick to send all requests through you.  I don't
know asterick at all but maybe you can configure your proxy as an
outbound proxy on asterick?  So that it will route all requests through
you first.



Or...I'm not 100% sure if this is possible or not - but you could try
adding an embedded Route header to the Contact Uri of Registrations that
pass through you.



Scott



________________________________
From: Steven Coule [mailto:Steven.Coule@xxxxxxxxx] Sent: Thursday, March 16, 2006 5:25 AM 
To: Scott Godin; resiprocate-devel@xxxxxxxxxxxxxxxxxxx
Subject: RE: [reSIProcate] Routing of signalling via proxy - opinions?

I wasn't intending my proxy to be the registrar, merely to route the
REGISTER requests to the registrar in addition to the normal proxying
behaviour of the call signalling. 


As an example scenario, I want to sit my proxy logically between an
Asterisk PBX (registrar) and the SIP phones it uses so that all calls
can be monitored using my proxy.



The tricky bit seems to be forcing the Asterisk to route calls to the
SIP phones via my proxy. It appears to ignore the maddr parameter and
send the INVITEs directly to the phones. Do you think Record-Route will
solve this? 


Thanks for the tip about repro, I've downloaded it and am taking a look.


Steve



________________________________
From: Scott Godin [mailto:slgodin@xxxxxxxxxxxx] Sent: 13 March 2006 18:43 
To: Steven Coule; resiprocate-devel@xxxxxxxxxxxxxxxxxxx
Subject: RE: [reSIProcate] Routing of signalling via proxy - opinions?



If the UA's register with your proxy and are only reachable via their
AOR - then using Record-Routing on the proxy is the way to go. 


You may want to take a look at repro - it is a proxy built ontop of
resiprocate.  Repro already supports record routing - you could just
extend repro to add your monitoring code.



Scott



________________________________

From: resiprocate-devel-bounces@xxxxxxxxxxxxxxxxxxx
[mailto:resiprocate-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of
Steven Coule
Sent: Monday, March 13, 2006 12:32 PM
To: resiprocate-devel@xxxxxxxxxxxxxxxxxxx
Subject: [reSIProcate] Routing of signalling via proxy - opinions?

I am developing a SIP proxy to monitor SIP call signalling using
reciprocate and need to force all call signalling traffic via my proxy
to maintain an accurate call state model.



For outbound calls from a UA, the UA can be pointed towards the proxy,
so that is straightforward. For inbound calls to any UA that I need to
monitor using my proxy, there needs to be some method for forcing call
signalling to my proxy rather than directly to the UA. For example, my
proxy could sit logically between an Asterisk PBX and a UA for that PBX,
or between a E1->SIP gateway and an array of UA's.



As far as I understand, there are a couple of approaches I can use to
achieve this ..



1)       Use the maddr= parameter. By forcing the UA to register with my
proxy, I can manipulate the REGISTER by adding the maddr= parameter
before forwarding the REGISTER to the real registrar. In theory at
least, this should force the inbound calls to be routed via my proxy by
the Asterisk / SIP server.

2)       Using the RFC3581 mechanism for NAT traversal appears to
provide a method of forcing a call signalling path via a specific proxy
using the Record-Route and rport= parameter. 


Have I missed anything? Which method is preferred?


Thanks,



Steve



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