Hi,
>Determining whether a response is a
>retransmission is actually hard, and not needed.
Is this true that a UAC doesn't need to determine whether a response is a
retransmission or not?
If so, wouldn't the UAC repeat the same processing for duplicate responses
which would impact performance, especially when the response includes SDP?
Thanks,
YoungSun
Jonathan
Rosenberg To: [EMAIL PROTECTED]
<jdrosen@dynami cc: [EMAIL PROTECTED], (bcc: Youngsun
csoft.com> Song/Telcordia)
Subject: Re: [Sip] Matching responses
to
04/10/02 12:59 transactions (error in 9th draft?)
AM
[EMAIL PROTECTED] wrote:
>
> Section 17.1.3 of the 9th draft of the SIP specification states the
> following:
>
> "A response that matches a transaction matched by a previous response is
>
> considered to be a restransmission of that response."
>
> This statement is preceded by two "matching rules", one about a matching
>
> branch parameter in the topmost Via header and one about a matching
> request method in the CSeq.
>
> Suppose that multiple responses are sent as the result of an INVITE.
> E.g.
> first a 183 Trying, then a 180 Ringing and then a 200 OK. All of these
> would match with the request, but according to the above statement, the
> 180 Ringing and the 200 OK would seem to be regarded as retransmissions
> of the 183 Trying. This can surely not be the intention.
Nope. This is an error in the spec. I think the right thing is to strike
the sentence entirely. The state machines are correct as defined, based
on the matching rules as defined. Determining whether a response is a
retransmission is actually hard, and not needed. Its not just the same
response code, since the same response could come from different
downstream UA. Its not a combination of response code and tags, since
the same UA could generate multiple provisional responses of the same
type (two 183, each with a different RSeq).
Thanks for pointing this out.
-Jonathan R.
--
Jonathan D. Rosenberg, Ph.D. 72 Eagle Rock Avenue
Chief Scientist First Floor
dynamicsoft East Hanover, NJ 07936
[EMAIL PROTECTED] FAX: (973) 952-5050
http://www.jdrosen.net PH: (973) 952-5000
http://www.dynamicsoft.com
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