dialogic was RE: [Asterisk-Users] "Glare" condition - How well does asteriskhandle?

[lists]

This may sound stupid but could you not off load the 4 pri max limit off to
a voice router.  I know it's not the cheapest way to go since dsp for a
hdv-2mft (cisco card) can run you a few K but would make it so your limited
by the Voice router limit so you get higher number of pri to a * box?  If so
could you not stack a bunch of these Voice routers together in * so that if
X number of call goto Voice router 1 then spill over to Voice router 2 and
so on.  I know 1750 cisco router with 2 mft and dsp are a lot cheaper then
buying a big box router with hundreds of DSP's.

I am still learning * but I am planning on replacing a CCM solution with *
as CCM is starting to get to buggy and costly for simple addons like
monitoring and multi phone hunt groups that ring all of the phone at once
like a 2or 4 wire PBX system.  We can no longer spend 50k -100k for such a
simple option. I just hope I can learn * well enough to replace the CCM's
sccp with sip w/o losing to much fuctionality.



My 2c 

Doug


-----Original Message-----
From: asterisk-users-admin at lists.digium.com
[mailto:asterisk-users-admin at lists.digium.com] On Behalf Of Steve Underwood
Sent: Thursday, May 27, 2004 8:09 PM
To: asterisk-users at lists.digium.com
Subject: Re: dialogic was RE: [Asterisk-Users] "Glare" condition - How well
does asteriskhandle?


Scott Stingel wrote:

>Hi Steve-
>
>Just briefly:
>
>I was mentioning the old days to illustrate what an even low clock rate 
>DSP can do.  More recently (2000-2001), using D/600's we were able to 
>drive a large number of channels (8-12 E1's) for IVR.
>  
>
Ah, the D/600 - damned big heat sink, lots of heat, and lots of cooling 
troubles. I remember them well :-) Actually, we are still using quite a few.

>All I'm trying to do is to illustrate both the beauty and the 
>limitations of taking the processor horsepower off the line interface 
>card and doing everything in the central processor.  The Digium boards 
>are MUCH less expensive than the Dialogic boards (about 15% the cost, 
>if that, per channel), but are not a plug-in replacement.  I've hit a 
>real-world limit, in my less-common environment, of about 4 E1's per 
>chassis.  I believe this limitation is not so much in the bit-rate i/o, 
>but the PRI call setup overhead.  I have communicated with a number of 
>other asterisk developers who have experienced this limitation, again in a
high-volume IVR
>environment.   I have demonstrated it to Mark as well...
>
>To get back to the original subject a bit, Dialogic developed an 
>elegant API called Global Call, which maybe we can use, or at least 
>learn something from.
>
>I'll let you have the last word if you like, Steve.... <s>
>
>Cheers
>Scott
>  
>
If the PRI setup is loading things that much there must be something 
wrong. That should be a very lightweight activity. It sounds like that 
bears investigation. Actually, with host based DSP short PRI calls 
should be a lighter load than long ones. The trunks spend rather more 
time not sending any audio, than with fewer longer calls.

Global Call is a mix of elegance and botchups. I actually have private 
code that implements something I call UniCall for the Digium cards, and 
a chan_unicall channel driver that works with it. This tries to be a lot 
like Globall Call, but without the botchups. I generally agree that an 
abstraction layer like that is a good thing.

I'm not trying to get the last word. I am trying to illuminate and 
improve things. If there are serious limitations they need kicking hard, 
not accepting. :-) There is no sound reason why things should be limited 
in the way you find. If you are doing call switching the Dialogic cards 
will win hands down on throughput. The audio never hits the CPU, and the 
limit is based on the number of call setup/cleardowns rather than active 
channels.
For simple IVR it is certainly not the heavy DSP load on the host CPU 
that is the limiting factor, and the Digium approach should do much 
better than you are finding it actually does. Heck, the Dialogic cards 
still don't bus master. The bus mastering on a TE405P/TE410P should give 
that a substantial win.

Regards,
Steve

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