[Blink] no audio if multiple ip-addresses are active

Adrian Georgescu ag at ag-projects.com
Fri Aug 13 17:34:46 CEST 2010


Not wanting to kill your enthusiasm, I actually will,
The problem you try to solve is many times over the complexity you imagine it is.

The real problem is that SIP and SDP require you to put IP addresses into them before you attempt to setup the session. Now you do not know beforehand where the session will end-up to, DNS may return an answer that points on a different network then your VPN, you may be redirected, forked etc and the final destination and here it split between both signaling and media might be on a different interface that you imagined before starting the call.

You try to solve a matrix of infinite possibilities. What you can certainly solve is your particular case only that will not help other users.

The only thing that works deterministically is the default route, which is good enough for generic Internet usage but not for VPNs. This is why whenever you have VPNs you have custom based solutions and applications supported by various vendors, which are not compatible one with another and each company has  a set of applications that are managed by a sysadmin that knows the particularities of that VPN.


On Aug 13, 2010, at 5:16 PM, Kenny MacDermid wrote:

> On 13 August 2010 11:39, Saúl Ibarra Corretgé <saul at ag-projects.com> wrote:
>>> :) well I do (if X-Lite can do it). It actually doesn't seem like it
>>> should be that difficult of a fix. Simply examining the connection to
>>> the SIP server and using that interface should work for most simple
>>> vpn configurations (and internet in general).
>>> Either way, using another random interface should definitely be a bug.
>> It's not random, it's the default route. Using another one would result in
>> failure for more people for sure.
> I mean the IP in my example. This is an IP and Interface
> that is both not the default interface, and not the interface that is
> used to talk to the SIP server (it's a random virtual vmware
> interface)
>>> Maybe I'll take a look at the source if I can get some time in the
>>> next week or two. Can anyone give me a pointer as to where to look for
>>> the code that generates these lines?
>> If you want to give it a try, have a look at python-sipsimple project, file
>> sipsimple/session.py, method connect.
> ty, will do.
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