On Sun, 18 Nov 2007, Iñaki Baz Castillo wrote:
El Domingo, 18 de Noviembre de 2007, Juha Heinanen escribió:
Iñaki Baz Castillo writes:
defining an outbound proxy should imply that the ua refuses to talk with anybody else.
Sure of that? does this behaviour appear in any RFC and so?
it is a common sense implementation issue of a sip ua, not a protocol (rfc) issue.
Anyway I think most SIP UA use "outbound proxy" (if configured) just for initial requests, not for incoming initial or sequential requests.
I think this is one of the topmost wrong behavior implemented in UAs: today, most UAs contains several "checkbox" for defining such behavior:
* send all message to an IP whatever its content. * send to an IP first message, for others, follow "normal routing rules". * always follow normal rules.
Other possible "checkbox" (about building content of messages): * always add an optionnal "pre-route" set. * add an optionnal "pre-route" set only if calling an "external address" (just to get the SIP trapezoid) * never add an optionnal "pre-route" even if the call is for a remote domain.
All those checkbox are just "workarounds" for proxy that are not correctly configured for example. * The Route header is often NOT removed in initial INVITEs and that leads to 483 Too many hops... * Some admin don't know about "record-routing"...
Is there any SIP UA with the behaviour you mean?
I've never seen any SIP UA in the market that don't have those "checkbox": except when they cannot be configured to use "any" network.
Even if I'm personnaly pushing my customers to use pre-route set and follow the "transport layer" routing rules: they require me to offer configuration alternative because they must be able to interoperate with any mis-configured/broken proxy. In 90% case, they just remove the pre-route set and makes it the default behavior. I cannot blame them....
Another well-know example is xlite. you have 3 checkbox: * outbound proxy * domain * target domain
-> Those are just variant of the SIP "transport layer".
-> In fact, among those checkbox, there is only 1 compliant way: but those options needs to exist to interoperate with mis-configured proxy. (Note that in most case, any of those algo leads to the same behavior if the proxy is correctly configured...)
My own opinions... Aymeric
Regards.
-- Iñaki Baz Castillo
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