[Asterisk-Users] How do I provide redundancy and reliability w/ Asterisk?

[phollenback at pobox.com]

Andrew makes some excellent points.  I'd like to ask if anyone else has
any info on what sort of device can be used to switch a T1 connection if
a T1 alarm is detected.

Also, is it possible to have a mixed setup where you have a T1 and
several POTS lines all feeding into the same Asterisk server?

Thanks,
P.

On 02/02/04, Andrew Kohlsmith wrote:
> > I'm trying to set up an Asterisk system for a small office, and one thing
> > I haven't figured out yet is how to best provide reliability.  One way
> > to go seems to be a T1 for all my incoming phone lines.  What if that T1
> > goes down?  Can I use mutiple POTS lines in conjuction with a T1, all
> > connecting to my Asterisk server?
> 
> As far as a PRI going down -- it's as likely as your POTS lines going down, 
> IMO.  Perhaps a little more so but in the end I have been in telephony 
> (dial-up internet) for close to 6 years now and on anything from single T1 
> PRIs to multiple DS3s, I have never had their end go down once it was 
> provisioned.  
> 
> I _did_ have the very unlucky experience of having a double-controller 
> failure on an M13 with no controllers handy once...  And to add insult to 
> injury UPS had lost the package from CAC not once, but twice.
> 
> > What if my Asterisk server fails?  Should I use two Asterisk servers, one
> > connected to the T1 and one to the POTS lines?
> 
> What I am doing (equipment is ordered, just waiting on it now)
> two * servers running identical hardware:
> - Dual power supplies
> - Linux software RAID1 on hot-swappable SCA drives
> - Single-proc P4 (dual proc mobo for expansion)
> - TE410P
> 
> We're talking CDN$3800-4200 systems.  The dual power supplies really adds a 
> lot to the cost, and the TE410Ps aren't cheap, either.  These are 
> SuperMicro 4U systems.  I looked at Dell and yes with warranty and 
> everything the systems were nice, but I couldn't justify purchasing 
> proprietary PC hardware in the end.
> 
> Both these systems are online all the time, but in a hot-failover instead of 
> load balancing configuration.  My telco's PRI (one right now) plugs in to a 
> little black box which has three T1 ports on it.  PRI goes in one side, and 
> two * servers to the other two ports.  The box monitors the T1 for alarms 
> and will physically route the T1 to the other port should any alarms come 
> up.  I saw this box on ebay once and have not been able to remember the 
> name of it.  If anyone has a name for a manufacturer, I would certainly 
> appreciate it.  It's my missing link at this time.
> 
> Each power supply plugs in to a UPS which is connected to alternate sides of 
> the incoming 240VAC.  (remember electricty 101?  North American power comes 
> in as two 120VAC lines and a neutral and are 180 degrees out of phase.  If 
> you're lucky enough to get three phase it's three hots 120 degrees apart, 
> but we don't have that at the colo, just at the plant.  :-) -- that way if 
> we lose a phase (it's happened before) we're covered, and if we lose both 
> phases the UPSes are there.
> 
> I do not have redundant internet links but will have two network switches, 
> one on each UPS -- I don't care if VOIP calls don't go through, but I need 
> the closet to be able to communicate.  :-)
> 
> Anyway yes if a * box goes down you lose all your current calls, but that 
> isn't a (big) issue for me.  The bigger issue is that when I go to place a 
> call that it gets through.
> 
> I will have one POTS line at the office, but it won't be hooked up to a 
> computer.  It will be wired to a regular phone with no bells and whistles, 
> and will be for emergencies.  It won't be equivalent to any of the DIDs.
> 
> The advantage to this setup is that while it breaks the hot-failover, I can 
> definitely test things on one box without causing hassles on the other, and 
> upgrades are trivial.
> 
> Regards,
> Andrew
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-- 
Philip J. Hollenback
philiph at pobox.com
http://www.hollenback.net