[Users] failover

[Cseke Tamas]

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?
And it could occur that  transactions in a dialog would be sent to 
different proxys, even if it isn't nessecarry?

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?

Thanks,
Tamas