Re: draft-ietf-mmusic-sip-session-timer-00.txt

[Jonathan Rosenberg <[e-mail]>]

Patrice Calhoun wrote:
> 
> I am sure that we will get to that one day :). However, I would like to
> understand why this would not work.
> 
> Here is an example:
> 
>     SC1 ------> SS1 --------> SS2 -------> SC2
> 
> In the above picture, Sip Client 1 (SC1) sends an invite along to its local
> Sip Server (SS1). The server adds some timeout information to the request
> and passes this along to SS2. If SS2 is satisfied with the timeout information
> added by SS1, it will leave it be. If SS2 requires a smaller timeout period,
> SS2 will modify the timeout value and pass the INVITE to SC2.
> 
> SC2 must response with an ACK. This ACK could include the timeout period, and
> could be checked by either SIP Server to ensure that it meets its local
> policy. The Sip Servers will assume that the session is destroyed within the
> timeout period, unless SC1 re-sends another INVITE message.

Thats pretty much whats specified in the Donovan draft. THe difference
is that the timeout doesn't get reflected in the ACK. THis is not
needed, though. The timeout should be echoed in the response, which will
be seen by both servers. I think this works just fine. The only issue
has to do with backwards compatibility - knowing that SC1 will
understand the timer in the response.

-Jonathan R.


-- 
Jonathan D. Rosenberg                       Lucent Technologies
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