[Freeswitch-users] FreeSWITCH HA + Loadbalancing

[Jim Burke]

High Availability is always an interesting problem.  PSTN equipment
generally overcomes it through duplication of messaging and hardware.
Obviously at an E1 (T1 for the US folks) or Subscribers Line Level
this is not possible.  This duplication comes at a cost and lowers the
calls per minute a softswitch can handle for the amount of hardware
purchased.  Like everything it is a trade-off between cost and
reliability.

Per Dave's comment, duplication on a network level can be achieved
easily through duplicating network switches and using OSPF, VRRP or
network bonding to ensure continuity if a path is compromised.  From
experience this is exactly what the vendors do and it does work.
During failover the calls experience a minut breakup of voice quality
but they still hold up ok.

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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-- 
Jim Burke
Director Evolutiontel.
http://www.evolutiontel.net