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<[email protected]> 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 > > _______________________________________________ > FreeSWITCH-users mailing list > [email protected] > http://lists.freeswitch.org/mailman/listinfo/freeswitch-users > UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-users > http://www.freeswitch.org > > > _______________________________________________ > FreeSWITCH-users mailing list > [email protected] > http://lists.freeswitch.org/mailman/listinfo/freeswitch-users > UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-users > http://www.freeswitch.org > > -- Jim Burke Director Evolutiontel. http://www.evolutiontel.net _______________________________________________ FreeSWITCH-users mailing list [email protected] http://lists.freeswitch.org/mailman/listinfo/freeswitch-users UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-users http://www.freeswitch.org
