[asterisk-users] Load balance Asterisk servers?

[Aaron Daniel]

On Tue, 2006-11-14 at 12:00 -0700, David Thomas wrote:
> On 11/14/06, Aaron Daniel <amdtech at shsu.edu> wrote:
> > Incorrect :) IAX2 most definitely does support regcontext.
> >
> > Also, I think what he means is the phone specific information must be
> > exactly the same from system to system or the failover won't be as
> > seamless as you expect.  A lot of phones support some sort of SRV
> > records, so in the event of a failure, the phones will automatically
> > find the next available server.  The other option there is to set up an
> > HA environment so the failover is even transparent to the phones, they
> > just start talking to the new IP address immediately.
> >
> > Another thought, in any failover situation, if you have any sort of
> > automated failover, you must make sure phones that need specific
> > features fail to the same server (i.e. hinting and such) as those
> > features don't work cross server.
> >
> > Aaron
> >
> > On Tue, 2006-11-14 at 08:16 -0700, David Thomas wrote:
> > > On 11/14/06, Stelios Koroneos <skoroneos at digital-opsis.com> wrote:
> > > > JR Richardson gave a very nice presentation at Astricon on how to do that with DUNDI
> > >
> > > As I understand it JR Richardson's DUNDi solution does not support
> > > IAX. It uses regcontex which I believe is only available with SIP.
> > > (please correct me if I'm wrong)
> > >
> > > Also JR notes that...
> > >
> > > "Associated SIP Users, business customers, require same registration
> > > and failover to the same servers" so unless this is for a residential
> > > setup, it may not be of much use to you. Nevertheless it is great
> > > documentation, and may get you further than you are now.
> > >
> > > regards,
> > > David
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> >
> > --
> > Aaron Daniel
> > Senior Voice Analyst
> > Sam Houston State University
> > amdtech at shsu.edu
> > (936) 294-4198
> >
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> 
> There I go spreading mis-information again. :)
> Thanks Aaron for clearing up the IAX2 regcontext question. That is good to know.
> 
> In the DUNDi scenario, are there any other features that would be
> affected or become unavailable in the event of a failure?
> 
> It seems like normal call processing would continue once the client
> re-registered to a different box, but I haven't tried it yet.
> 
> I assume one could use DNS-Round-Robin to load balance registrations
> between the boxes in the cluster, then pull the failed box out of DNS
> to prevent registration attempts while the box is dead. Is there a
> better way to do this ???
> 
> David
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The "best practice" for the failover situation will depend on the phone
you're using, and what kind of failover you're looking for.  Most *real*
phones support SRV records which will contain the list of servers that
your phone should talk to.  If the phone sees one server down, it
automatically jumps to the next available one.  You are correct however,
that call processing would still work as long as you have the servers
configured correctly :)  Also, if you configure the phone correctly, you
should theoretically be able to not lose any calls in case of failure as
well, however you would lose call details records for that call.

Douglas Garstang will tell you round-robin won't work, I haven't tested
it.  Something about random packets going to round-robined server
addresses :)

The other thing to consider is actual failover ip addresses, where one
computer automatically assumes another computer's ip address in the
event of failure.  The phones would automatically start talking to the
new system immediately.
-- 
Aaron Daniel
Computer Systems Technician
Sam Houston State University
amdtech at shsu.edu
(936) 294-4198