[Freeswitch-users] FreeSWITCH HA + Loadbalancing

Mon Aug 31 05:22:23 PDT 2009

A random thought.  It strikes me that adding support for live call
failover to FreeSWITCH might well be the wrong thing to do - it's
something which is probably not too difficult to achieve if starting
from the ground up, but which is going to be a right PITA to do
retrospectively.  And, once you've done switching, there's conferencing,
IVR stuff...

Here's an alternative approach.  Have two FS boxes (which I'll call FS1
and FS2 - you can't fault *my* imagination) and a front-end B2BUA/RTP
proxy with a bit of a difference.  The B2BUA sends incoming stuff to
both FS1 and FS2 as two separate call legs, and the RTP proxy forwards
inbound RTP to both FS1 and FS2.  Assuming that FS1 is the current
"master", it forwards RTP and call state transitions from FS1 back to
the caller.  If it detects that FS1 has gone away, then - as FS2 should
be in roughly the same state as FS1 - it flips to using FS2 as its
source.

The internal state of the B2BUA/RTP proxy should be relatively simple,
and therefore should be able to be duplicated to a hot standby.

I can see a collection of gotchas, such as registration (the B2BUA needs
access to the user database), and I haven't even begun to try to think
of how to deal with calls *from* the FS boxes.  Actually, that's not
true: I have, and they clearly need to go through the same sort of
mechanism in reverse, which is fine until I start trying to work out how
to pair up calls from FS1 and FS2 reliably, and then my head hurts.

But I think that this idea has merit.  Firstly, it abstracts the
failover mechanism away into one place; secondly, it is general - FS1
and FS2 could just as easily be Asterisk1 and Asterisk2.

And I'll do it for just $98,650..

--Dave

> Your forgetting that with RTP theres the duplication of RTP that may be
> required along with a mechanism that keeps media timers working properly...
> 
> Where many things don't support RTP timers they sure come in handy on a
> regular basis especially dealing with several of the other software based
> platforms out there that just love to have calls end but never want to send
> a BYE
> 
> 
> > From: Jim Burke <jim at evolutiontel.net>
> > Reply-To: <freeswitch-users at lists.freeswitch.org>
> > Date: Mon, 31 Aug 2009 12:54:50 +1000
> > To: <freeswitch-users at lists.freeswitch.org>
> > Subject: Re: [Freeswitch-users] FreeSWITCH HA + Loadbalancing
> > 
> > Conceptually in a pure SIP installation of Freeswitch, hot standby or
> > active standby could be achieved through duplication of messages
> > (INVITE, 200OK and BYE for calls) between 2 boxes and then using VRRP
> > to change the IP address when the box falls over.  Going this way
> > allows call state to be as up to date as possible.  Obviously this
> > would require logic added to sofia to transfer the RTP port
> > information and UUID information between the FS instances (Easily
> > achieved using additional SIP headers).  It would also require that
> > sofia does not forward duplicated messages to gateways or user agents.
> >  CDR information would also need to be generated correctly (My
> > experience of Radius with Opensips is that it generates start and stop
> > messages on INVITE/200OK then BYE respectively so this could be an
> > easy solution to the CDR issue).
> > 
> > Regards,
> > 
> > 
> > 
> > On Sun, Aug 30, 2009 at 11:19 PM, Raimund Sacherer<rs at runsolutions.com> wrote:
> >> So, the first way would be to have a look on the sip stack, which is, in
> >> fact, sofia ..., well, sound's like a nice, fun, long-going hobby project to
> >> me :-)
> >> I will definitly at least look at the sip code to check if it is something i
> >> would myself willingly give over to ...
> >> But I *really* do want  a setup where it does not matter if one specific FS
> >> instance is UP or NOT ...
> >> 
> >> --
> >> Raimund Sacherer
> >> -
> >> RunSolutions
> >>     Open Source It Consulting
> >> -
> >> 
> >> Parc Bit - Centro Empresarial Son Espanyol
> >> Edificio Estel - Local 3D
> >> 07121 -  Palma de Mallorca
> >> Baleares
> >> On Aug 29, 2009, at 10:04 PM, Brian West wrote:
> >> 
> >> The sip stack needs to be modified to spin that data up into the state
> >> machine so that it can take over calls once the fail over takes place... its
> >> not an easy task.
> >> /b
> >> On Aug 29, 2009, at 2:56 PM, Mitul Limbani wrote:
> >> 
> >> Is itnpossible to have a db cluster know the state of each and every call
> >> and then use Heartbeat on this db +
> >> fs cluster so that clients see only one ip where as internally all fs boxes
> >> refer db for call states, db again is under replication.
> >> This in the thioery can be written, but I am sure if we think bit more on
> >> this direction the problem seem to be getting addressed.
> >> Other guys also chip in their 2 cents, we just need 50 of em to make a full
> >> dollar.
> >> 
> >> Thanks & Regards,
> >> Mitul Limbani,
> >> Founder & CEO,
> >> Enterux Solutions Pvt. Ltd.,
> >> The Enterprise Linux Company (r),
> >> http://www.enterux.com
> >> http://www.entVoice.com
> >> 
> >> _______________________________________________
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> >> 
> >> 
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> >> 
> >> 
> > 
> > 
> > 
> > -- 
> > Jim Burke
> > Director Evolutiontel.
> > http://www.evolutiontel.net
> > 
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> 
> 
> 
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-- 
David Knell, Director, 3C Limited
T: +44 20 3298 2000
E: dave at 3c.co.uk
W: http://www.3c.co.uk