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

Kenny MacDermid kenny.macdermid at gmail.com
Fri Aug 13 18:21:02 CEST 2010


Hi Adrian,

Thank you for the background information. I see the complexity when
you can use different interfaces for SIP and RTP.

The scenario that I still see (possible mistakenly) as being better
than the current one is to use the interface through which you're
talking to the SIP server instead of the default route. It should then
continue to use the default interface for the vast majority of people,
but work for /some/ people behind VPNs.

Would you see a lot of cases where general users would have SIP on
non-default, and media established on the default interface? I see
this use case as much less common than the non-split case. Does Blink
keep track of anything like this so we can see how commonly it is
used?

So yes, I'm not looking to solve the general problem, merely make the
more common use case work (at the cost of the less common one
breaking). Just to clarify, I perceive the more common one as when
signal and media travel on the same interface, and that interface is
the one used to contact the SIP server. Am I wrong?

Thanks again,

Kenny

On 13 August 2010 12:34, Adrian Georgescu <ag at ag-projects.com> wrote:
> Kenny,
>
> 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.
>
> Adrian



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