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

[Paul Belanger]

On 12-05-06 02:00 PM, Nunya Biznatch wrote:
> 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.
>
800 SIP phones on one server? I wouldn't want to do it. Add a SIP proxy 
to your design and have it handle all your SIP.  Then you can load 
balance across multiple asterisk boxes.  You'll be thankful you did this 
at the start, as it will allow you to increase resources more easily.

>
> 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...
>
Why?

> 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.
>
It is ashame you are going this far with your setup to rely on FreePBX. 
  For something this complex, you are setting your self up for some 
heartache.

> 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.
>
-- 
Paul Belanger | PolyBeacon, Inc.
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