[asterisk-users] Improving Asterisk's DNS support

[Brian Capouch]

Kristian Kielhofner wrote:

> 
>  The intent of my original message was to try to start a discussion
> on how we can fix a REAL, KNOWN problem with Asterisk to make it
> better.  I'm not sure what the exact problems are (or even the
> specific symptoms in all cases), but  I am willing to offer anything
> that I can (money, testing, etc) to fix this problem.
> 
>  I realise you don't know that this is a problem.  However, your tone
> is *not* what I am looking for in this discussion.
> 

For those who haven't ever been bit by this "situation," please believe 
that it is not only real but devastating.

Kristian is exactly right: there needs to be an architectural fix that 
will stop EVERYTHING in the server from hanging when lookups are done 
(and then hang) for a given IAX/SIP peer.

I'm not programmer enough to do it, but once it's done I will be 
eternally grateful.

Just yesterday I had a situation where our egress circuit was being used 
temporarily to do a big remote database dump.  As a result, DNS queries 
to the outside world were taking forever to resolve.  An internal server 
I have, which talks to a single DNS-named peer in the outside world, 
hung tight, repeatedly, while the T1 was compromised, even though none 
of its calls had anything to do with that peer.  It was the core engine 
that was hung up waiting.

The worst of it is when there are Zaptel cards in the box, it doesn't 
even handle call pickups and the like once the DNS hang has begun.

There are various kludgy workarounds, but at the end of the day it does 
not seem that the server should hang totally when this situation occurs.

B.

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