Subject: [SIP] Retransmission after provisional resp. - UAC side

From: "Piotr S. Kossowski" <[email-masked]>
Date: Tue, 31 Oct 2000 22:02:04 +0100

Hello,

Let me invoke retransmission thread again:

Section 10.4.1 (rfc2543bis-02):

"(...)If the client receives a provisional response, it continues to 
retransmit the request, but with an interval of T2 seconds.(...)"

I'm confused or I can't understand general idea of retransmission.

To my mind, Retransmission is a way for delivering 100% information
from one entity (UAC) to another (UAS, proxy). Till the moment
when we have not got any signal from peer that it received
everything what we wanted to send, we should continue of delivering,
preserving our information intact (retransmission should not carry
new information). That's general rule.

As a server send provisional response It means that it received
100 % of our information - request (at least, we assuming so). Thus, 
Retransmission of request will not supply new information to the server
(and shouldn't change server's state).

My question is: What is the reason for retransmiting of request,
even thouht the server has confirmed reception of our request
(by sending provisional response) ?

Thanks in advance,
Piotr

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---

From: Billy Biggs <[email-masked]>
Date: Tue, 31 Oct 2000 15:16:19 -0600

Piotr S. Kossowski ([email-masked]):

> [...]
> My question is: What is the reason for retransmiting of request, even
> thouht the server has confirmed reception of our request (by sending
> provisional response) ?

  To poll for a final response which may have been lost.

-- 
Billy Biggs, 3Com               Email: [email-masked]
http://www.div8.net/billy/      Phone: [email-masked]