[Asterisk-Users] System Design

Thu Mar 9 08:09:23 MST 2006

Thanks for all of your replies!

I was thinking the server was a little overboard, but I want this to
last and also be expandable.  We might be adding users/offices within
the next year so I wanted to plan ahead.

The DSL speed at the remote office is 1.5 to 6.0 Down and 384 to 608 up.
The DSL does have a static IP address and it's pretty rock solid in
regards to stability.

I was planning on buying the G729a codec from Digium for use on all
calls.

In regards to:
<snip>
For normal incoming and outgoing calls, just have the asterisk box at
that particular location handle it (no need for the remote office to
connect to the main office's asterisk box, then call out via iax or sip
for a long-distance phone call).
</snip>

Would the remote office * need a couple of POTS lines to make those
local calls?

Once again thanks for all of your replies!  They are definitely clearing
things up for me.

 - Jason 

-----Original Message-----
From: asterisk-users-bounces at lists.digium.com
[mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of Joseph
Tanner
Sent: Wednesday, March 08, 2006 6:54 PM
To: Asterisk Users Mailing List - Non-Commercial Discussion
Subject: Re: [Asterisk-Users] System Design

Lot of questions, lots of variables, but I'll touch base on a few
things.

5-10 concurrent calls is hardly anything.  A plain T1 will more than
handle that, even at ulaw or alaw (non)compression.  Throw in a decent
codec, and 10 calls won't even put a dent in your T1.  Heck, it'd handle
all 20 users in your main office, and the 5 users in your remote office
with G729, no problem.

How reliable is the remote office's DSL connection?  I'd make sure you
have a static ip for it (dynamic ips are just slightly problematic,
especially if you have slightly flaky service, coupled with a slightly
flaky modem).  If it's reliable, then just keep that.  What's the
connection speed?  Need to know the upload and download.  If it's ADSL,
then the upload will be a fraction of the download, and will be the
limiting factor.

Since I don't know your specific setup, I can't tell you specifically
what to do.  I'll make some guesses though.  Keep DSL.  No need to use
VPN just for asterisk.  Make sure each end has a static ip (dynamic ip
will work, but is harder to setup and more prone to errors).  Have each
asterisk box register to the other.  For normal incoming and outgoing
calls, just have the asterisk box at that particular location handle it
(no need for the remote office to connect to the main office's asterisk
box, then call out via iax or sip for a long-distance phone call).  You
can create "local" extensions that when dialed, will ring a person on
the other asterisk box.  I.e., a user at the main office can dial 2001,
and get a user at the remote office.  If you deal with call queues you
can group users from both offices together, no problem.

A T1 or a point to point connection at the remote office would work, but
is probably unecessary.  If their DSL connection is flaky and
unreliable, then start looking at both options.  I'd probably go with
whichever is cheapest, be sure to factor in equipment costs (you can
generally lease equipment with a T1 line, but not with a point to point
connection).

As far as server specs, if all it's going to run is asterisk, then
that's overkill even if it was handling all the calls.  If you think you
need that much server but are on a budget, then get one setup for dual
processors but with just one installed, and less ram but that has room
to add more.  If budget's not a problem, I say go for it!  That system
should last you for quite a while.

As for QOS, sorry I can't help you there.  You could get a cheap router
that has QOS built-in, or run a separate low-end server just for QOS.
Personally my asterisk box also serves as my nat server, so I just run
QOS directly on it.  It's probably not something you want to do in an
office environment, but it's better than no QOS at all. 
Hopefully someone else will give you some good advice on QOS equipment.

Joseph Tanner

On 3/7/06, Jason Adams <jadams at sumosystems.net> wrote:
>
> Hey Everyone,
>
> We are in the works of planning a new * installation for our company.

> We have 20 users in our main office and 5 users in a remote office a 
> couple of states away.  Our call volume for the main office will be 
> anywhere from 5-10 concurrent calls.  The remote office will have 
> about 3 heavy users with two users making calls occasionally.
>
> Right now we have an existing PBX.  We have a T-1/PRI coming into the 
> main office and a DSL connection at the remote office.  We have a 
> Cisco 2610/PIX
> 501 at the main office a cheesy linksys router at the remote site.
>
> We are planning on purchasing new Cisco IP phones for everyone.
>
> My main question is this:  What type of hardware/network design would 
> be best for this situation?  Would a full T-1 at the remote site work 
> with a VPN between the offices?  Or would a higher bandwidth DSL work
with a VPN?
> Or should we move to a Point-to-Point connection?  What type of 
> hardware would be best for the end-to-end communication in regards to 
> QoS?  I know the PIX 501 doesn't support it.
> Would it be best to have two * servers in each office or for that call

> volume at the remote office does it make sense?  I was thinking of a 
> Dell Power Edge server with 4GB of ram and a dual processor.. is that
enough?
>
> Sorry for all the questions!
>
>
>
>  - Jason
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