2011/6/15 Alex Hermann alex@speakup.nl:
However I've seen other SIP stacks also performing failover by taking next NAPTR records. But indeed, RFC 2915 does not mandate it, instead it says MUST NOT. So you are right.
I forgot about a discussion i had about this issue a few years ago with a customer and just remembered the outcome now. (Optional) failover can be provided by different 'Preference' field within the same 'Order'. From rfc 2915/3403 section 2:
The important difference between Order and Preference is that once a match is found the client MUST NOT consider records with a different Order but they MAY process records with the same Order but different Preferences. I.e., Preference is used to give weight to rules that are considered the same from an authority standpoint but not from a simple load balancing standpoint.
Yes, 100% right.
Unfortunately this wasn't possible with Kamailio <=1.5. Have you tried 3.x with equal 'Order' but different 'Preference' or just with different 'Order'?
Not yet, but I'll do it and comment here :)