Thanks to both. It's clear. I had some doubts since RFC 3265
(obsoleted by 6665) allows multiple subscription dialog creation if a
proxy forks a SUBSCRIBE. But those dialogs are created in the UAC upon
receipt of each NOTIFY with different From-tag (rather than creating
the dialog upon the receipt of the *single* 200 OK for the initial
SUBSCRIBE).

Thanks.


2012/8/16 Brett Tate <[email protected]>:
>> Hi, if a UAC sends a SUBSCRIBE and the proxy does parallel forking to
>> two servers, it could occur that both servers reply a 200.
>>
>> Should the proxy relay the second 200 to the UAC? or should it absorb
>> it?
>
> It should be consumed instead of relayed by the proxy.
>
> RFC 3261:
>
> "This step, combined with the next, ensures that a stateful
>  proxy will forward exactly one final response to a non-INVITE
>  request, and either exactly one non-2xx response or one or more
>  2xx responses to an INVITE request."
>
> RFC 6026:
>
> "When receiving any SIP response, a transaction-stateful proxy MUST
>  compare the transaction identifier in that response against its
>  existing transaction state machines.  The proxy MUST NOT forward the
>  response if there is no matching transaction state machine."



-- 
Iñaki Baz Castillo
<[email protected]>

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