Subject: [SPIRITS] Re: [Fwd: I-D ACTION:draft-ietf-spirits-protocol-01.txt]

From: "Vijay K. Gurbani" <[email-masked]>
Date: Tue, 07 May 2002 16:54:26 -0500

Jonathan:

Inline (some text quoted to provide context for people on the list).

vkg> Yes, RFC 2995 is an Informational RFC only.  ICW is still possible
vkg> with the current SPIRITS architecture and protocol, except that
vkg> SUBS/NOT is not needed for this particular service.  It happens
vkg> automagically; and INVITE is sent straight out to the IP host.

jdr> OK, so where is that documented? Or, are you saying, its really
jdr> obvious and there is no need to define standards for it?

vkg> The SPIRITS requirement I-D (which is in the RFC queue with IESG)
vkg> provides some guidance on this:
vkg>    One specific example demonstrating the application of the latter
vkg>    requirement, which is elaborated on further in this document, is as
vkg>    follows: Implementation of SUBSCRIBE/NOTIFY is not mandatory as far
vkg>    as the minimum SPIRITS protocol is concerned.  Thus, the initial
vkg>    PSTN (Detection Point) notification will always arrive via the SIP
vkg>    INVITE method; however, to implement persistent interactions with
vkg>    the PSTN, the SUBSCRIBE method may be used to obtain further
vkg>    notifications to the PSTN events. Subsequently, these events
vkg>    will be reported on by means of the NOTIFY method.
vkg>
vkg> Thus, ICW, as a SPIRITS service can be done completely using the
vkg> initial INVITE request.

jdr> This is why I am confused. I don't see any discussion of invite in the
jdr> spirits protocol. Maybe I am missing it. If i'm not, I don't get it
jdr> - if the requirements say that protocol X needs to support INVITE,
jdr> I would expect to see INVITE in the protocol.

Okay; so I see your point -- the use of INVITE is not described in the
protocol I-D.  This is probably my fault -- I have been focusing rather
heavily on the SUBS/NOT aspect of SPIRITS in earlier iterations of
the protocol I-D.  In the next iteration, I will add the use of INVITE
as well, as per the requirements I-D.

vkg> This was done to be backwardly compatible
vkg> with the existing ICW implementations, which pre-dated the SPIRITS WG.
vkg> Furthermore, when these ICW implementations were done (late '98 - mid
vkg> '99), SUBS/NOT was not even on the horizon (PINT had a SUBS/UNSUBS
vkg> extension to SIP, which I guess subsequently gave birth to SUBS/NOT).

jdr> Well, you can't do ICW with just SUB/NOT anyway, so its not just an
jdr> issue of backwards compatibility.

Right.

Regards,

- vijay
-- 
Vijay K. Gurbani  vkg@{lucent.com,research.bell-labs.com,acm.org}
Wireless Networks Group/Internet Software and Services
Lucent Technologies/Bell Labs Innovations, 2000 Lucent Lane, Rm 6G-440
Naperville, Illinois 60566     Voice: +1 630 224 0216

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