[asterisk-users] Replacing PBX with Asterisk, need feedback on my new architecture.

[Nunya Biznatch]

I'm about to receive approval to design and deploy an Asterisk-based 
phone system for my company. I will immediately have to start writing 
specifications. I'm working on the hardware design and the architecture 
right now. I'd like a second, third, fourth, 1,000th opinion.

800 SIP phones. All will be G.722. I expect 200 concurrent calls, with 
20% leaving to the outside world. There will be another 200 analog lines 
that will for the time being remain on the TDM PBX switch they reside 
on, and will be whittled down and converted to SIP as time and attrition 
allows. These are primarily fax machines and conference "spider" phones. 
Those are included in my 200 concurrent calls number. I'm looking to get 
as close to 5-9's reliability as I can, with 4-9's mandatory. Proper 
power filtering and backup is already available.


Here's what I'm thinking for the architecture:

Server 1: PRI Gateway 1 - Support 2 outside PRI trunks for local and 
long distance, plus a third PRI connecting to the existing TDM PBX.

Server 2: PRI Gateway 2 - Support 1 PRI trunk for local and long 
distance with room for another, plus a second PRI connecting to the 
existing TDM PBX.

Reason for two PRI Gateways is for redundancy and fail-over, but 
processor capabilities is a concern. I expect in about two years I'll be 
ready to decommission the TDM PBX, but will be left with about 80 Analog 
lines across the multiple buildings on my campus. I expect I'll end up 
purchasing channel banks to support the remaining analog lines, and 
distribute across the campus using existing copper plant.


Server 3: Asterisk Master Server

Server 4: Asterisk Slave Server

I'm considering a clustered environment, but I believe a fail-over 
solution would be easier to implement in the short term. This means each 
system needs to handle all traffic by itself. These servers will be used 
for Asterisk and Voice-mail. Conferencing will be enabled, but I'm not 
considering it in the build. If I see conferencing becoming a factor, I 
will build another server and offload that service.


Server 5: Boot Server - DHCP, RADIUS, SNTP, DNS, LDAP, FTP, HTTPS, SNMP, 
etc...

This service will provide the phone network all the basic services. This 
is a stand-alone phone network primarily because it would be too costly 
to upgrade the entire data network to support both voice and data. The 
phone network will not initially have Internet Access. This server will 
be the server all the phones talk to for pulling their configs.

I'm considering a second Boot Server for redundancy, but since the 
phones should store their configs, I'm not seeing this as horribly 
critical. Am I smoking something?


Finally, I'll have a Windows-based workstation that will be used to 
remote into all the services, for administration, etc...

I need to plan to use FreePBX on all Asterisk Servers, but I don't 
intend to install it until I'm in regular MAC maintenance mode.

I have no plans at this time to build out any databases. I just plan to 
use whatever Asterisk has. If it ever comes to that, I would make those 
separate servers as well.

My goal is to build Asterisk Servers and PRI Gateways capable of 
supporting 150% of what I anticipate, which would come out to 300 
concurrent calls. Again, all phones will use G.722. The PRI Gateway 
servers will do the heavy lifting of converting G.711 traffic from the 
PRIs to G722, and connect to the Asterisk Servers via IAX2 trunk.

It's my intention to build each server myself with high-quality off the 
shelf components. I'd like all servers to be as close to identical as 
possible, as I intend to keep spares on hand to facilitate quick repair 
and minimize downtime. I'm considering RAID 1 + 0 (mirrored and stripped 
drives) for all servers. I am considering dual redundant power supplies.

For a processor, I'm currently looking at the i7-3770K @ 3.5GHz or very 
similar. Its Passmark compares to the Xeon E5-2630 @ 2.3GHz, but is half 
the price.

I have no idea what amount of memory to consider, so I am thinking 8GB 
per machine.

PCI-E is what I plan for all the cards.

Debian is the Linux flavor

A new network will be deployed using PoE layer-2 managed switches. 
Battery backup capable of providing 8 hours will be installed as 
required. There will be multiple VLANs in the network as I have multiple 
dissimilar offices I need to keep separated from each other. We will 
also have 802.11 SIP phones, and will be deploying a campus-wide WiFi 
network used only by the phone system. Yes, I crunched the numbers. This 
will be significantly cheaper than upgrading the entire existing data 
network to support the new phone system. ...and to be quite honest, I 
don't trust our network folks, and know adding that layer of bureaucracy 
will only negatively impact the customer experience. I was a network 
engineer for a top-three telecom company for many years, so I do have a 
point of reference to make those statements.

...yes, I am one guy looking to do all this, with an estimated 
completion date of the end of 2013. I'll be building all this out in 
addition to my normal "phone guy" job. I've built servers (hardware and 
software) for 20+ years, but my Linux Kung Fu is weak. I'll be learning 
by doing and know there'll be a lot of extra hours. The boss is good 
about training, so I hope I can get into a good Linux Admin class in 
addition to dCAP.


So tear it up! What do you think? Does the CPU have the oomph? What am I 
missing? What am I overkilling? What would Brian Boitano do?

I appreciate any feedback, and thanks in advance.

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.digium.com/pipermail/asterisk-users/attachments/20120506/a9b59e2d/attachment.htm>