Subject: Re:[Sip] Last Call: The Refer Method to Proposed Standard

From: "Sriram Parameswar"<[email-masked]>
Date: Tue, 21 May 2002 10:19:28 -0500

Hi:

A couple of comments on the Refer draft.

1. It would be good to add REFER to the table in Section 3 and put "m" for
Mandatory against the Refer-To header. This would clarify what is in the
text just below - also its in keeping with other draft published (example:
events draft section 8.2).

2. I had sent a similar comment to the list on 4/26/2002. Section 4.2.2 and
section 8.2 of the Events draft
http://www.ietf.org/internet-drafts/draft-ietf-sip-events-05.txt (reproduced
below for convenience) show that the Subscription State as a mandatory
header in a NOTIFY method. It would be good to include these in the
examples. I would also like to suggest a small discussion on the semantics
of the Subscripton-State header, they will be useful especially in
out-of-band REFER's to give the referor (originator of REFER) some idea when
he could retry a REFER. For example the discussion could read:

	 The NOTIFY to a REFER MUST contain a Subscription-State which
indicates the status of the subscription. Typically for a successful REFER,
the NOTIFY SHOULD contain a Subscription-State of "terminated". It may not
contain a reason code for the termination, however if one exists it SHOULD
be "timeout" (for success cases). For cases where the REFER failed or was
rejected (especially out-of-band REFERs) the Subscription-State header with
its"reason" and "retry-after" parameters provides important information as
to when the REFER may be retried, see the events drafts [EVENTS] for the
semantics of the reason codes and the "retry-after" parameters. Please note
that the message/sipfrag body will contain the specific reason the REFER
failed.

Thanks,

Sriram Parameswar

----------------------Section 4.2.2 Events
draft------------------------------
NOTIFY requests MUST contain a "Subscription-State" header with a value of
"active", "pending", or "terminated". ...If the value of the
"Subscription-State" header is "terminated", the notifier SHOULD also
include a "reason" parameter. The notifier MAY also include a "retry-after"
parameter, where appropriate.
----------Section 8.2 Events draft
Header field 		where proxy ACK BYE CAN INV OPT REG PRA SUB NOT 
Subscription-State 	R                     -       -        -       -
-        -     -        -       m 

__________________________________________
Sriram Parameswar              Phone: 972-685-8540
Interactive Multimedia Server (IMS) Fax: 972-684-3986
Nortel Networks, Richardson USA  Email: [email-masked]