27 Feb
2008
27 Feb
'08
12:17 p.m.
El Wednesday 27 February 2008 11:04:00 Bogdan-Andrei Iancu escribió:
Hi Taisto,
As mentioned in a previous email, the RFC3261 says that the 200OK ACK
forms a separate transaction:
17 Transactions (page 122)
....
The reason for this separation is rooted in the importance of
delivering all 200 (OK) responses to an INVITE to the UAC. To
deliver them all to the UAC, the UAS alone takes responsibility
for retransmitting them (see Section 13.3.1.4), and the UAC alone
takes responsibility for acknowledging them with ACK (see Section
13.2.2.4). Since this ACK is retransmitted only by the UAC, it is
effectively considered its own transaction.
.....
And OpenSER is doing this - 200OK ACK is not part of the INVITE
transaction.
Now, about destroying the INVITE transaction after 200OK, I not sure if
the RFC really states this. The RFC says the transaction is completed
with the 200 OK, but not destroyed - this is more or less an
implementation option, in my opinion.
Hi Bogdan, about that there is lot of info in this draft:
http://tools.ietf.org/html/draft-sparks-sip-invfix
It fixes the RFC3261 by removing the need of destroying the INVITE
transmission when a 200 Ok is received. Instead it suggests to keep the
transacction in memory for a while ("completed" status) to match request
retransmissions and other replies in case of parallel forking.
But the original RFC 3261 seems to indicate to destroy the INVITE transaction
in the UAC/Proxy when a 200 Ok is received.
Regards.
--
Iñaki Baz Castillo
ibc(a)in.ilimit.es