[Asterisk-Users] Asterisk redundancy

[Tim Panton]

On 17 Apr 2006, at 12:58, Joseph Rothstein wrote:

> I'd like to start a discussion about Asterisk redundancy. I know  
> this has
> been covered in the past, but would like to get an idea of what  
> people are
> doing for a production system that must be up "all" the time.
>
> Assuming a single E1 out.
>
> Here are some of my ideas.
>
> HA Linux between the two asterisk boxes. But I am not sure how the  
> Asterisk
> DB would handle a fail over. What happens to the SIP registrations?  
> Can the
> Asterisk DB be offloaded to MYSQL for example? The local DB is  
> importatn
> because this is a call center with agents logged in to multiple  
> queues.
> Config could either be realtime or duplicated manually. What about  
> recorded
> message, has anyone had any problems with an NFS volume providing  
> recorded
> messages such as periodic messages in queues? This solution would  
> require a
> manual swap of the E1 cable inthe event of failure.
>
> Is anyone using a PRI to Ethernet bridge, or any other kind of E1  
> GW that
> would allow failover to an alternate Asterisk box without manually  
> switching
> the cable? This one is a litte
> expensive(http://www.mapleleaf-technologies.com/webstore/ 
> ethernetbridges.php
> ), but seems like it would do the trick. But I would have to run TDMoE
> between the Asterisk boxes and the bridge. Not a big deal probably,  
> but I
> have no experience with TDMoE.
>
> I would appreciate any comments regarding redundancy, and how  
> people are
> solving these problems.
>
> Regards to all,
> Joe

I strongly advise you to get the economics clear before you proceed.
Get an estimate of the business costs of (say) 1hour's downtime every  
3 years.

Once you have done that you have a budget to work to. If you don't  
and you
just follow the "No downtime ever!" rule two things will happen:
	1) you will spend a boatload of money, probably far more than
needed.
	2) You will fail. 100% uptime doesn't happen - ever - folks get close,
but every step costs exponentially more, and gets exponentially more
complex - so much harder to maintain - so more fragile.

Also don't forget to talk to your telco and hear what they can do for  
you.
You may find that they can detect a PRI failure and move calls to a  
fallback
number (mobiles, analog, answerphone, voicemail,voip provider).

I _very_ much doubt you can find a solution where you can have
the box at your end of the PRI fail (be it an asterisk or a switching  
box)
and still keep the current calls.

Keep us posted on what you find, it is an important topic and my
views ("keep it simple") aren't typical :-)

Tim.

Tim Panton
tim at mexuar.com