[SR-Users] Double Session Description Protocol Version (v) 0 data when using rtpengine

[Wilkins, Steve]

Thank for your insight and honesty Alex!  I do appreciate feedback as it helps us grow...no matter our age.

-----Original Message-----
From: sr-users <sr-users-bounces at lists.kamailio.org> On Behalf Of Alex Balashov
Sent: Wednesday, October 24, 2018 9:01 AM
To: Kamailio (SER) - Users Mailing List <sr-users at lists.kamailio.org>
Subject: Re: [SR-Users] Double Session Description Protocol Version (v) 0 data when using rtpengine

More generally, Steve, responding to some themes I see in your posts over the past few months:

You have a habit of posting overblown speculations about problems and painting yourself into grossly overcomplicated interpretations that send you down spurious paths of troubleshooting.

I think you need to seriously ponder Occam's Razor:

https://en.wikipedia.org/wiki/Occam%27s_razor

If you're running into an unexpected phenomenon, why do you assume it's a bug in Kamailio or a "de novo" problem? In fact, a little Googling will reveal that double SDP stanzas are a common question.

https://lists.kamailio.org/pipermail/sr-users/2015-August/089538.html

The simplest explanation is almost ALWAYS the correct one. Yes, occasionally it is possible to find a true, honest-to-god original bug in the product -- we all have. But it is not the explanation you should start with, nor one you should readily leap to, because it requires a lot more assumptions, so probabilistically, it is almost always the wrong theory. 

Consider it in terms of thermodynamics, mathematics, and the complexity introduced by additional moving parts if you like:

If you see an unexplained flash of light, there are numerous possible explanations. Some are quite simple: optical-neurological phenomenon, reflection from the mirror of a passing car, etc. Some are extremely complicated and involve novel, unproven ideas in physics or cosmology.

"Hey, what was that flash of ligth?"

Which should you start with FIRST? Think about it critically ...

-- Alex

On Wed, Oct 24, 2018 at 08:51:12AM -0400, Alex Balashov wrote:

> I think you've crawled down that rabbit hole about two millennia 
> prematurely. There is a much simpler explanation for why you're 
> getting a duplicated SDP stanza - in the logic of your route script. 
> It's not a bug in Kamailio.
> 
> I can't tell you exactly what the cause is, but I believe this avenue 
> of exploration will prove fruitful. It's a fairly common problem.
> 
> On Wed, Oct 24, 2018 at 12:49:55PM +0000, Wilkins, Steve wrote:
> 
> > I was looking at the sdpops_mod.c code hoping that there was an easy way to remove a sess_version (Session Description Protocol Version (v): 0) structure, but there does not appear to be that functionality in that module.  It might be a bit of work to remove a duplicate sess_version line.
> > 
> > I am using Kamailio 5.1, does anyone know if this is an issue in later versions?
> > 
> > Thank you,
> > -Steve
> 
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> 
> 
> --
> Alex Balashov | Principal | Evariste Systems LLC
> 
> Tel: +1-706-510-6800 / +1-800-250-5920 (toll-free)
> Web: http://www.evaristesys.com/, http://www.csrpswitch.com/
> 
> _______________________________________________
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> sr-users at lists.kamailio.org
> https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users

--
Alex Balashov | Principal | Evariste Systems LLC

Tel: +1-706-510-6800 / +1-800-250-5920 (toll-free)
Web: http://www.evaristesys.com/, http://www.csrpswitch.com/

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