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

[Scott Stingel]

Hi Paul-

I actually said 4 E1's to a chassis (one TE410P) was best I've been able to
do.  And yes I do believe that it is the short call profile (large number of
call setups) that contributes to the limit - if you're doing longer calls
then the limit seems to be more related to the number and type of
transcoding you're doing.

But anyway, its pretty easy to test an IVR scenario if you have two systems
(and two Digium quad E1 cards).  Build 4 E1 crossover cables and use one
system as a call generator and the other to receive.  On the sender, I wrote
a script that generated short calls on a pseudo-random basis.  On the
receive side, I simply answer, play a prompt, and hang up. 

This is how I came up with my observed limit.  It sort-of works at 120
channels, with lots of framer re-tries, but if you try all of this with a
second board in each, like 5-8 spans, - no way.  All of this with a dual
Xeon 2.6GHz.  Same results with a 2.8 P4.

But again I stress that this is an admittedly worst case scenario.

Cheers
Scott


Scott M. Stingel
President,
Emerging Voice Technology, Inc.
Palo Alto California & London England
www.evtmedia.com 

-----Original Message-----
From: asterisk-users-admin at lists.digium.com
[mailto:asterisk-users-admin at lists.digium.com] On Behalf Of Paul Crick
Sent: Thursday, May 27, 2004 1:38 PM
To: asterisk-users at lists.digium.com
Subject: RE: dialogic was RE: [Asterisk-Users] "Glare" condition - How well
does asteriskhandle?

> Lets see. Early 90s would be ISA cards in an industrial PC chassis 
> full of ISA slots. Heavy IVR means talking most of the time. 3k 
> bytes/s per voice for the commonest 24K ADPCM mode most people use 
> with Dialogic. So, 12 E1s is 360 channels. 3kbytes x 360 = more than 
> the ISA bus can handle, before I even add up the disk loading. Does 
> not compute.
Not sure on the math there, but the company I worked at previous had 10 x
D/SC480-2T1s and a D/SC240-T1 in a single ISA chassis.. 21 PRIs = 483
channels. Chuck in a 4 port analogue card for system admin, and you're
pretty much as big as you can go, limited now by SC-Bus timeslots (we were a
handful under the max I think). Worked well with dual pentium IIIs, with
relatively heavy call load.

There's a bunch of these still in production, and they've since moved to PCI
cards, cramming 28 T1s in to a single chassis.. ok, not the best design -
I'd have preferred lots of smaller interlinked systems, but not my
decision..

> On the other hand, how come you can only do 2 E1s of IVR with *?
This is the thing I keep wondering about.. is it due to there being little
processing power on the Digium cards, them relying more on the host CPU to
do stuff?

Having read the list and the stuff Scott Stingel's posted, I'm inclined to
believe that a single 4 port T1/E1 card is the best way to go in a large
scale installation, even with 2 cards in the same box I'm pushing it/risking
it? Granted, he's doing high call volume with low duration (televoting and
stuff right?) so maybe the overhead is on the call setup and tear down? If I
had call hold times running in to minutes and tens of minutes, could I stick
8 T1s in a box and not have problems?

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