[Kamailio-Users] Question regarding TM module DNS failover with SRV records

[Nathan Angelacos]

Iñaki Baz Castillo wrote:
> El Jueves, 10 de Diciembre de 2009, Daniel-Constantin Mierla escribió:
>> does the 503 reply include a retry-after header?
> 
> Does Kamailio behaviour depends on that header? If so IMHO it's not correct.
> 
> I've joined long discussions in sip-implementors about 503 with/without  
> Retry-After header. Some people think that a 503 without this header must be 
> considered as a 500. But after discussions this assumption is not correct and 
> a 503 must be considered similary even if it doesn't contain this header.
> 
> BTW RFC 3263 (Locating SIP Servers) says nothing about 500 error, neither 
> about Retry-After header in 503 replies. It considers a 503 with/without 
> Retry-After in same way.
> 
> IMHO Kamailio/SR should consider Retry-After just as informative but never 
> change the routing/failover behavior based on it.
> 
> Regards.
> 

Thanks for that background info.

Personally I don't care which way it goes, as long as its documented. 
So that google will find this next time:

FWIW... Kamailio 1.5.3 follows 3261 21.5.4, even if it is confusing[1].

But [2] mentions that OpenSER 1.1.x was "RFC 3263" compliant - which 
treats Retry-After as informational in section 4.3.



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[1] 
https://lists.cs.columbia.edu/pipermail/sip-implementors/2006-April/012532.html

[2] http://www.kamailio.org/mos/view/OpenSER-v1.1.x-Release-Notes/