[Asterisk-Users] Re: 911 and lawsuits and redundancy

[Steven Critchfield]

On Thu, 2004-01-08 at 18:50, Jonathan Moore wrote:
> Quoting Steven Critchfield <critch at basesys.com>:
> 
> > If you come at your install with a couple of computers, you can have a
> > similar effect. My main asterisk machine has the PRI attached to it.
> > This machine does little work, and receives next to no upgrades. It was
> > locked down and does just PSTN gateway work. I have another machine in
> > the same rack as the PSTN gateway that hosts one of our apps. This
> > machine may get more frequent upgrades if we ever notice problems with
> > the software or if we need newer features. Our office switch is a
> > similar beast. Updates when needed, but it affects fewer people. My home
> > machine connects to the PSTN gateway, but my home machine is usually
> > bleeding edge and sometimes my working version. At worst case my home
> > machine only affects 3 people, 2 of which have cell phones.
> 
> This is very interesting. I was hoping someone was running a setup like this.
> Lets say that in theory I have a server that is fast enough to handle all my
> pstn connections and all of my internal extensions. I have multiple sites
> connnected via single mode fiber. Is there a benefit of placing a "local" *
> server in each building without pstn connectivity with the local connections
> going to an * server with the pstn connections? Would this be better than
> running the single server?
> 
> Now lets expand on this idea with 2 extras
> 
> 1. Add a second * server at the central point and split the pstn lines between
> it and the first unit. In this setup how would you program the local * to call
> either pstn gateway as needed? Is there a way to share the analog lines between
> the two gateways such that if one box dies the other unit detects and takes over
> their usage?
> 
> 2. Add some VoIP service accounts for the organization from someone like Vonage,
> etc so that if the fiber connection goes down the local * server will continue
> to allow outbound calls via there cable modem and connection to the Internet. Is
> it possible to have a "pool" of a few voip accounts that could be shared like
> these amongst the buildings? One issue we have right now with local redundancy
> is that just a single pots line at each building as backup with actually double
> our entire phone bill. This is because most of our calls are internal so we
> don't need very many pstn lines compared to desktop phones (6 lines to 150
> stations is the current ratio).
> 
> With either or both of these additions how would you share a central dial plan
> and what can you do to simplify maintenance in terms of the * configurations?

My opinion would be to place a small switch at each building. This would
allow you the ability to use actual analog phones in each building if
you wanted to. 

Your configuration question, if you put the dialplan on a central
location, any of the remote machines would place the call to the central
location and then the central location could route. The nice part about
IAX like SIP is supposed to, the calls will get transfered if possible
and will route directly instead of back to the central location. 

As for the idea of splitting the trunks up and using both. Depends on
what you want to do. It is possible to do a blind dial to a primary
server, and then if it completes, fine, if it fails, you dial backup
server. You could go more sophisticated and try and load balance by
setting up a toggle variable that could let you send every other call to
the "primary" and then every other call to the "backup". 

It has been mentioned here that there needs to be a more sophisticated
return code return by dial as you wouldn't be able to discern a busy as
failure to contact a gateway or a actual real busy signal on the line.
-- 
Steven Critchfield <critch at basesys.com>