[Asterisk-Users] System Design

[Colin Anderson]

This doesn't directly answer your question, because every integration
scenario is different, but one of the nice things about Asterisk is that the
barrier to entry to get a system working and play around with it is very
low. What you might want to consider doing is get your Asterisk box working,
minus the PRI card, get the Cisco phones running (you're going to buy them
anyway) and put them in place, side by side with the current phones, and
just have the everyone play with them. That alone will answer a lot of your
questions about how to engineer it without commiting to a particular way. 
 
However, in your remote office, I would ditch the crap router and at least
use a Monowall http://m0n0.ch/wall/ <http://m0n0.ch/wall/>  because you can
prioritize traffic with it, it's super easy to set up, and you can make it
work with odds and ends you have laying around. If you have more than one
static IP, you can even do a Monowall to Monowall VPN and leave your PIX in
place, and then run the VoIP over the VPN. Monowall supports IPSec VPN's, so
you can interface it with a lot of other firewalls out there, including Pix.

 
Running VoIP over a VPN is sometimes problematic (but sometimes it works
great!) so again you can try it out without committing. 
 
Sometimes it makes sense to have a remote Asterisk server at the other end
and route calls via IAX, IAX is like a VoIP dream protocol, but on the other
hand it adds complexity where complexity is undesirable. You should try it
both ways: Stick in a remote Asterisk server on the other end, route calls
via IAX, and also have some Cisco's register with your main Asterisk server
over SIP (both with and without the VPN)
 
The Dell will probably be fine, compatibility issues with Digium TDM cards
nonwithstanding (there are some - ask Digium when you buy) and in your case,
overkill. I'm running a Netfinity Xeon 550 (yup, 550 Mhz) with 2 Te110P
cards right now supporting 180 users in 32 locations in a 50 mile radius.
Looking at the console right now I have 36 of 46 channels open to my PRI's,
50 mixed SIP and IAX calls, and top says about 16% with load average about
.53. And I'm recording all the calls. 
 
On my remote IAX sites (30), I have between 2 to 5 users that do SIP to a
local IAX server, then IAX here to the main office and out the PRI. What's
running on the remote servers? Frigging P-II 233's. That's all. The reason
it works is because I am careful with codec selection so there's no
transcoding. And the call quality is just fine, thank you. 
 
Ask the boss for a couple of weeks to experiment, get the gear, and test.
That will give you the optimum result, instead of my jackass opinion.
 
hth

-----Original Message-----
From: Jason Adams [mailto:jadams at sumosystems.net]
Sent: Tuesday, March 07, 2006 4:26 PM
To: Asterisk Users Mailing List - Non-Commercial Discussion
Subject: [Asterisk-Users] System Design


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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