[asterisk-dev] NFAS Implementation Spanning Multiple Servers

[Steve Totaro]

> -----Original Message-----
> From: Chris Parker [mailto:cparker at segv.org]
> Sent: Friday, February 03, 2006 12:32 AM
> To: Asterisk Developers Mailing List
> Subject: Re: [asterisk-dev] NFAS Implementation Spanning Multiple
Servers
> 
> 
> On Feb 2, 2006, at 7:44 PM, Steve Totaro wrote:
> 
> >
> >
> >> -----Original Message-----
> >> From: Chris Parker [mailto:cparker at segv.org]
> >> Sent: Thursday, February 02, 2006 8:27 PM
> >> To: Asterisk Developers Mailing List
> >> Subject: Re: [asterisk-dev] NFAS Implementation Spanning Multiple
> > Servers
> >>
> >>
> >> On Feb 2, 2006, at 5:04 PM, Steve Totaro wrote:
> >>
> >>> Hello Dev Folks,
> >>>
> >>> Recently I asked a question on the list about NFAS being able to
> > span
> >>> across multiple servers.  Kevin F said that this was something in
> > the
> >>> works and should show up very soon.
> >>>
> >>> I have a real need for this.  I have a T3 going into an Adtran
> > MX2800
> >>> and then into seven asterisk boxes with quad T1 cards.  The way
> > things
> >>> are now, I need seven D channels to go PRI.
> >>
> >> Put two quad cards in each box?  4 D's for the entire CT3.
> >>
> >> 8 is the limit on how many T1's I've run w/o running into problems
> > with
> >> NFAS in the dialup world.  And that's with fewer CPS than voice
> > traffic
> >> will see.
> >>
> >> -Chris
> >> --
> >
> > We considered this but with 1U boxes and a single card per box,
> > even if
> > one server dies, the impact would be minimized.  4T1s instead of 8.
> 
> How many go down when you loose the D channel?  You've got exposure to
>  > 4 PRI going down either way.  Your choice.  :)

I don’t understand what you mean.  If I have a server with two four (4)
port T1 cards that is eight (8) T1s on one box.  Last I knew, T1 cards
are not hot swappable, so you will have to take eight (8) offline at
some point, instead of just four.  To me it makes more sense to put my
eggs in different baskets speaking from a hardware failure viewpoint.
With two D channels in a multi server spanned NFAS setup, there is a
backup.
 
> 
> > Besides, going from seven to four is not that much of a cost
> > savings to
> > justify the redundancy issue of having separate boxes.
> 
> How many D channels are you thinking you'll get this down to?  2?  Is
> $200 / month difference worth the added complexity of multi-chassis
> NFAS?
> 

Two cards per server is pretty much out of the question.  The price
difference is negligible and the 1U servers take up less room and
provide more redundancy (less eggs in one basket).

So, it would be a savings of $500/month, going from seven to two.  If it
cannot be done in Asterisk then I will probably look at the large Adtran
(cannot remember the model name) that can actually alter and create the
channels rather than just breaking them up and passing them on.  The
price was around $20,000 I believe.  

I am sure the configuration of this high-end Adtran will add just as
much complexity as multi-chassis NFAS.  Probably even more complex since
Asterisk is pretty easy to configure.  I have yet to play with the high
end adtran box.

Thanks,
Steve
 

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