[Users] failover

[samuel]

see inline...

2006/5/9, Cseke Tamas <cseke.tamas at eworldcom.hu>:
> Hi Bogdan,
>
> >> That means, if one proxy dies during the session, the UA'll make a
> >> DNS SRV lookup, find the other proxy, and send the BYE to it instead
> >> of the proxy, which served the INVITE?
> >
> >
> > not quite - all sequential request (within the dialog) are routed
> > based on the route set (the Record Route hdr added by the proxies on
> > the path). The headers contains IP addresses, so basically no DNS
> > lookup is done for sequential requests. An alternative will be to
> > configure your proxy to put DNS name instead of IP in the RR hdr.
> >
> I 'd like the UAs to make only DNS lookup, when one proxy fails, if the
> proxy put domain name in The RR header, the UA must do a DNS lookup in
> every request, isn't it?

It should be (that's why it's always recommended to use FQDNs instead
of IPs in SIP headers).....but I bet thousands of beers that many UAs
won't do SRV lookup for every message.

> And it could occur that  transactions in a dialog would be sent to
> different proxys, even if it isn't nessecarry?
>
As long as request-response reaches the same proxy, it's ok to use
different openSERs...be carefull with the database backend so you do
not have different contacts for the same user...take a look at
cacheless mode of operation.

> Would be nice, if the transaction target would change, only for failover
> reason.
>
> example.com
>
> _sip._udp IN SRV 0 1 5060 server1.example.com
> _sip._udp IN SRV 0 2 5060 server2.example.com
>
> server1.example.com IN A 128.59.26.1
> server2.example.com IN A 128.59.26.2
>
>
> UA lookup SRV,and reaches server1.
> server1 want to stay in the signaling path,  (Record-Route:
> sip:128.59.26.1)
> during the session server1 fails, when the message should be sent to
> server2.
> The UA try server2 or give up and the BYE never will be sent to any server?

It completely depends on UA implementation....that's the problem of
SRV failover. Some of them would do it properly and some of them will
return error messages to users (just guessing from experience).

>
> Thanks,
> Tamas
>
>
>
>
>
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You could also try to set up a dispatcher as load balancer and a farm
of openser behind.......


Samuel.