Subject: [Sip] BIS-03 and UAS BYEs

From: Terry L Anderson <[email-masked]>
Date: Wed, 18 Jul 2001 11:10:22 -0400

The first paragraph of 15.4 of draft-ietf-sip-rfc2543bis-03 is a big
improvement being more explicit about when subsequent requests can be
sent but there still seems one ambiguity.  Since BYE and CANCEL are
neither "regular transactions" or "INVITE transactions", they are not
covered by the paragraph.

But my greater concern is when UAS state is not in "Completed" state
(Figure 11) and yet INVITE transaction is over: can UAS send BYE.  That
is, UAS has returned 200 OK but not yet received ACK, called party hangs
up (or otherwise called UAS wishes to terminate): can it send BYE.  I
believe that it should NOT.  That it must wait for ACK and then send BYE
(or wait for 7- 200 OKs without receiving ACK), but I cannot see that
this is covered by the paragraph.  Is it covered somewhere else?

--
Waiting for the other shoe to drop while hoping it's a one legged man.
------------------------------------------------------------
Terry L Anderson              mailto:[email-masked]
Tel:908.582.7013   Fax:908.582.6729
Lucent Technologies/INS/Voice Over IP Access Networks
Rm 2B-121, 600 Mountain Av, Murray Hill, NJ 07974
http://its.lucent.com/~tla (Lucent internal) http://www.gti.net/tla

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From: "Rahman, Mohib" <[email-masked]>
Date: Wed, 18 Jul 2001 09:37:54 -0700

Terry,

Two weeks back similar discussion was continued in sip-implementors mailing
list and conclusion was that BYE can be sent by the Called party if it sends
seven 200 OKs and receives no ACK. Actually BYE makes sense if the call is
established. And in this scenario from the UAS perspective the call is
established.

But I don't see any explicit reference of this scenario in bis-03. Does
anybody see this in bis-03?

Regards,
mohib

-----Original Message-----
From: Terry L Anderson [mailto:[email-masked]]
Sent: Wednesday, July 18, 2001 8:10 AM
To: SIP Mail List
Subject: [Sip] BIS-03 and UAS BYEs

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From: "Ghai, Rajat (Rajat)" <[email-masked]>
Date: Thu, 19 Jul 2001 19:27:48 -0400

In my view, sending a BYE
right away without waiting for an ACK should be OK. 
The reason being that, if the user has hung up, why keep that UAS blocked
for 'x' amount of time while it could be initiating or terminating new
calls. (makes a lot of sense for Gateways which are acting as B2B UAs and
tying up precious RTP Codecs). The orphaned "ACK" which the UAS might
receive later
can be dropped as it does not belong to an active call and does not require
a response anyway.

Similarly, a UAC should be able to accept a BYE to tear down a session any
time after receiving  a 200 OK. It still sends an ACK (if it hasn't sent
already) though followed by a response for the BYE. 

I do not think PROXYs get affected by this.

thanks
Rajat Ghai