[asterisk-users] WAS: 64 analog phones NOW: Selection criteri a and recipie for a good Asterisk install [long]

John covici covici at ccs.covici.com
Thu Sep 28 09:14:01 MST 2006

OK, pardon my ignorance -- but what can you tune on such a system?
How does Linux handle separate buses?


on Thursday 09/28/2006 Colin Anderson(ColinA at landmarkmasterbuilder.com) wrote
 > >I concur with your approach, but "Tier 1" means as little here as it
 > >does when evaluating Internet backbone carriers.  could you expand on
 > >what evaluation criteria you use?  I'm going to be pre-speccing some
 > >stuff myself this month...
 > Sorry I should have been more clear. A good Asterisk install needs a
 > holistic approach to use a hippy dippy phrase. A Tier 1 server, which is a
 > midrange to high end name brand server from the Big 3 (Dell, HP/Compaq, IBM,
 > am I missing someone?) is usually highly optimized for bus bandwidth
 > although that design was intended for a different use - usually massive disk
 > I/O. As well, a Tier 1 server will have two seperate, independent PCI buses
 > and this to me is a critical feature - it allows you to completely separate
 > your TDM traffic from network, disk I/O etc. On my big production Netfinity,
 > I took great care to ensure the Digium cards were all on their lonesome on a
 > single bus, and everything else on the other bus. This is how I can run two
 > TE110's in a single box with no problems. zttest does not give me 100% all
 > the time, but on the other hand it *never* drops below 99.9987%, even under
 > load. I selected this Netfinity because of the obvious care put into it's
 > design, but the specs are unimpressive: quad Xeon 700's. CPU is over rated
 > for Asterisk, IMO unless you are doing tons of transcoding and if you are
 > doing that, then your design is flawed. 
 > Anyway, the holistic approach (to go on a small rant for the newbie lurkers)
 > be summed up as follows:
 > 1. Good box, see above
 > 2. Good LAN - this is so critical and so often overlooked in the day and age
 > of guys crimping their own cables and running $150 switches. You can't do
 > that, and if you do, you do so at your own peril. Managed swiches,
 > professional cable installation. This is not a problem for me since I *am* a
 > professional cable installer but I have actually witnessed people making
 > patch cables with a flat blade screwdriver and a hammer!
 > 3. Tuning of the LAN - VLAN's are good. QoS packets are good. Switches that
 > honor the QoS packets are good. 
 > 4. Handset selection - this is another biggie. I've selected Snom 360's, and
 > yes they have warts, but they are feature rich for the price and Snom is
 > really good about revising firmware. When you select handsets, GET YOUR
 > 5. Tuning of Asterisk box itself - this cannot be under emphasized. This is
 > a very important step and tuning methodologies vary according to distro,
 > skill of the admin, and particular circumstances. I've learned *way* more
 > than I ever wanted to about processor affinity sinc I started using
 > Asterisk. 
 > 6. Termination of PSTN. Basically I would never do an Asterisk install where
 > I was forced to do something stupid like aggregate a dozen Centrex lines or
 > some mickey mouse deal with FXO ATA's or whatever except for a hobby or
 > prototype install. PRI, BRI, IAX or SIP, don't mess around with anything
 > else. 
 > 7. Relationship with provider. What is their SLA? Is it the incumbent or the
 > clec? An incumbent will be more expensive and more difficult to deal with
 > but they will tend to be more reliable. A clec will be cheaper and they will
 > be way more accomodating but you will most likely not get five 9's from
 > them. A VoIP provider should never be trusted, period. You will not get five
 > nines from them, ever. Plan failover situations accordingly. 
 > 8. Plan plan plan plan. A good install of ANYTHING is 80% planning 20% doing
 > it. What is your plan when your primary PSTN provider fails? What is your
 > plan if your Asterisk box goes pear shaped? My dialplan can survive either
 > PSTN, WAN or LAN failure (albeit with reduced functionality). I also keep a
 > cold spare, an identically configured box that I can literally throw into
 > the rack, turn it on, plug in the PRI's and no problem. 
 > 9. Internet bandwidth and latency. I am fortunate enough to have a great IP
 > provider. Ask for demos - most guys will install a 90 day trial or something
 > like that. Do not believe the brochure, get the product installed and put it
 > under load. 
 > 10. Traffic prioritization at the IP demarc - total no brainer. 
 > 11. Constant, constant user feedback and remediation. If you are not talking
 > to your users, your install will ultimately fail even if you have the best
 > of everything. Underpromise and overdeliver. Never loose sight of the basics
 > - they have to pick up the phone, and it has to work. Always. 
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Your life is like a penny.  You're going to lose it.  The question is:
How do
you spend it?

         John Covici
         covici at ccs.covici.com

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