On Thu, 2009-08-20 at 14:51 -0400, Andy Spitzer wrote:
> Woof!
> 
> Raymond asked me this question.  I open it up to the wisdom of
sipx-dev.
> 
> I think the essence of the question is:

>   When using DNS SRV, when an INVITE is challenged, should you then
> send the new INVITE with the credentials back to the server that
> requested them, or do you start the DNS SRV lookups all over again,
> potentially getting a different server?

The answer with respect to sipXecs is that it doesn't matter; a nonce
generated by any proxy is acceptable at any other in the same domain
(for as long as the challenging proxy would have accepted it - they do
time out).

If I were implementing it, I would not repeat the 3263 lookup process,
I'd re-use the result chosen for the first attempt, if only because it
would work for proxies that don't have interchangeable nonce values like
sipXecs does.

> ------- Forwarded message -------
> From: "Raymond Chandler" <[email protected]>
> Subject: DNS SRV
> 
> Mike Jerris told me to email you in regards to the proper handling of
> DNS SRV records for SIP.  Specifically, we have an issue with sending
> INVITEs to a proxy, getting challenged and sending INVITE w/auth to
> another proxy since all have the same priority and weight.
> 
> It was said that if the weight is 0, then the first chosen host should
> be used throughout, but any other weights would cause the normal
> selection process to occur on every new transaction.  The references
> we've been going off of thus far are RFCs 2782, 3263, and 3261.

I can't find anything that supports any such special case - did you have
a citation?



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