Subject: Some initial queries/comments on draft-ietf-sip-183-00.txt

From: "David R. Oran" <[email-masked]>
Date: Mon, 25 Oct 1999 14:05:29 -0400

Thanks for all the careful work on this guys! Here are few questions and
comments based on my initial reading:

1) you don't make clear which pieces of this are intended to be specific to
the 183 response message and what pieces are intended to be generic. For
example, it would seem that the "Session: media/qos/security" header is much
more generic. In the abstract and introduction, it might be best to say
you're making TWO extensions to SIP, the Session header, and the 183
response.

2) This may just be me having shell shock flashbacks to my ISO days, but I
cringe when I read all these "shalls" in section 2.1. All of them read much
better if replaced by "should".

3) following on from the logic above in point 1, it is implied but not
stated that the "Session": header could be placed on the initial (or
subsequent) INVITE. This certainly makes sense for the qos & security forms,
and could conceivably be useful for the "media" form as well.

4) I know this may be a can of worms, but if we ever want to allow multiple
SDP bodies in SIP messages it would behoove us to ensure that headers that
refer to body part treatment can explicitly say WHICH body instance they
refer to.

5) the MUSTs in section 4.2/4.3 seem a bit strong. Nothing breaks if the
sender is slow or sloppy at stopping; the user might get some mixed audio or
be annoyed though. While I can't off the top of my head think of any
positive use for the continued transmission (maybe the "call is being
monitored" beep tone...") I'd like to hear why such strong prohibition is
called for. There is also the philosophical question of what actually
constitutes "temporary" media, especially in the case where the SDP
describing the "permanent" media is identical to the SDP describing the
"temporary" media.

6) Section 4.4, second paragraph. While I see that 183 may not be
appropriate for ringing, forwarding, or queued (since we have other
responses for these), the used of Session: media may be perfectly
appropriate. Is this just another instance of not becing clear about the
relative independence of the Session: header and the 183 response?