[asterisk-users] Where is the Digium DS3 card?

[Steve Totaro]

On Mon, Apr 7, 2008 at 2:01 AM, Alex Balashov <abalashov at evaristesys.com> wrote:
> Michael Cargile wrote:
>
>  > Another reason I am sure that Digium has not released a DS3 TDM card is
>  > the fact that asterisk currently cannot handle that many channels. I am
>  > speaking from experience on this. We have build before a predictive
>  > dialer with 16 PRIs. In order to do this and not have audio quality
>  > issues we had to use an 8 core Intel Xeon server with 16 gigs of ram, a
>  > 6 drive RAID 10, and two octal echo canceling Sangoma cards. This also
>  > required numerous OS tweaks and dial plan optimizations. The amount of
>  > time spend on this was not worth the final product.
>
>  I hope some optimisations were made to the ViciDIAL code as well, where
>  surely the greatest efficiency gains are to be reaped.
>
>
>  > In the mean time, if someone really needs to handle that many channels I
>  > would suggest purchasing a DS3 to T1 mux and pass the T1s onto mutliple
>  > Asterisk servers setup in a cluster. In the end you will end up spending
>  > far less money and time setting the system up. I also saw recently at a
>  > trade show a DS3 to SIP converter which might also lower the cost as you
>  > would not need T1 cards. The only issue is that they are a some what new
>  > technology where as DS3 to T1 muxes have been around for some years now
>  > and can be found on ebay for around 700 dollars.
>
>  Good ISDN gateways with DS3 interfaces that can output a whole DS3 of
>  VoIP channels are hard to come by.  A Cisco AS5400 claims to, and has
>  the DSP density for it, but between its processing power and its TDM bus
>  cannot handle much more than about half of that.  Of the Cisco media
>  gateway line, as AS5850 is probably your best bet.
>
>  A Lucent TNT Max outfitted with _plethoric_ VFCs might work okay.  Apex
>  too, perhaps.  Haven't tried to see how much it can handle when TDM->RTP
>  translation is required.
>
>  The cluster idea you suggest is probably most economical, but it sure
>  does require a lot of redundant T1 interfaces.
>
>  --
>  Alex Balashov
>  Evariste Systems
>  Web    : http://www.evaristesys.com/
>  Tel    : (+1) (678) 954-0670
>  Direct : (+1) (678) 954-0671
>  Mobile : (+1) (706) 338-8599
>

A T3 MUXed into 28 T1 PRIs in one, or a few trunk groups inherently
has redundancy.  If a box dies, the calls are dropped (unless you are
doing reinvite) and any call backs go right to the
Ts that are not in alarm.

Running stripped down Linux OS boxen with quad port T1 cards and four
or five lines in extensions.conf, no unneeded modules or software
loaded, asterisk 1.2, entries for zaptel and zapata, and a couple
entries in sip.conf builds a worry free solution.  Asterisk uptime 2
years, system uptime two years and twenty minutes.

Thanks,
Steve Totaro