Subject: [SIP] Draft Minutes of SIP WG at IETF 48,

From: "Dean Willis" <[email-masked]>
Date: Wed, 30 Aug 2000 16:01:04 -0500

A better-formated (simple HTML) version can be retrieved from:
http://www.softarmor.com/sipwg/meets/IETF48/minutes/index.html

Minutes of SIP WG at IETF48 (Draft)

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Edited by Dean Willis, 8/28/2000

Monday Session
_____________

Agenda Bashing and Startup

Scott Bradner reviewed IPR notice.
Karen O'Donahue volunteered to take notes.
Proposed agenda review, no discussion.

Status of Working Group Efforts -- led by Jonathan Rosenburg

Guidelines for Authors proceeding as expected.

Caller Preferences proceeding, some discussion on removal, agreement to
proceed to last call.

Info draft

Reliability of Provisional Messages submitted to IESG on July 10.

Supported/Server features on IESG agenda for consideration.

Open List Issues -- Rosenburg

Multiple transport parameters (Transports:). Could be a new parameter, or
could be lisetd in the Contact: field with multiple Contact: headers.
Discussion ensued, with both SRV (poor for negotiation) and SLP (possible
for interdomain) mentioned. Henning summarized consensus that the number of
transports is relatively small and the existing mechanism seems to work for
now.

How to handle OPTIONS and REGISTERS if max-forwards-0? Suggestion made that
OPTIONS return 483, REGISTER be silently discarded. lennox objected to
special behaviors for different methods. Henning asserted that max-forwards
is really for debugging, and the handling isn't all that critical.

Additional Detail on error Messages (Dave's Error Messages): Sparks suggest
use of Refer (to, by) headers. Dave Oran prefers new failure-info header.
Olson and others argues against overloading  Contact. Henning argued need
for explicit header. General consensus resulted on basic Dave mechanism with
new explicit header.

Mandatory UDP: Some hot debate, no real conclusion. Lawrence Conroy argued
need for a simple TCP-only system, and Jonathan Lennox noted that making UDP
mandatory has security implications for systems that are trying to use TLS.

DTMF discussion was deferred to Session 2.

Embedded Images: Much discussion on issues of size, direct vs. indirect
embedding  and relating content to messaging. Henning Schulzzrinne, Adam
Roach, Sean Olson, and Scott Petrack made points. General consensus seemed
to be to stay with 2543 approach and to prefer indirect reference where
feasible.

Case Sensitivity of URLS: (URI Comparison) general consensus for documented
approach. Rohan Mahy suggested some sort of locally extended flexibility be
considered.

Session-Timer: Several changes reveiwd. Jonathan Lennox asked if it is
legitmate for a Require: header to be inserted by a proxy.

Context and Architecture for SIP-T -- Aparna Vemuri

Purpose: feature transparency.

Issues
* SIP MIME type negotiation - standard 415
* Want to be able to tell a UAS to ignore certain MIME types

- ISUP repitition problem: * not all ISUP parameters are needed; many will
contain information
from origination side

Changes in DCS -- Bill Marshall

All six drafts now in compliance with rfc2026.

Manyfolks: handling of case where UAS wants preconditions, but UAC didn't
indicate support for it

Privacy: 1) Needed to add proxy-require. 2) Removed authentication ?? sip
security task force will handle.  3) OSPS removed. 4) Editorial changes to
align with Guidelines.

State: 1) Usage of Supported/Require added . 2 )Interaction with Hide. If
Via headers hidden, then state headers need to be hidden -> resulting in
Proxy-Require. 3) will change syntax to include port number.

Call Authorization: only minor editorial changes

Architectural Draft: Much larger in size

Proxy-Proxy: 1)  DCS Specific extensions tracing of obsence and harassing
calls resource coordination for packetcable call transfer and three way
calling. 2.  OSPS, Billing-Info, Require and Proxy-Require used. 3) Next
steps: * design complete, * maybe issues for inter-domain operation, * 4
documents for proposed.  Consensus was achieved on adding four proposed
drafts as wg items. Informational draft will be on hold until proposed
documents are complete.

Update on rfc2543bis -- Henning Schulzrinne

Nothing thats not backwards compatible. Not SIP/2.1.

Lots of clarifications:

* ACK Forwarding
* consistencies between tables and texts
* e-e vs. h-h distinction has been deprecated, different table
which describes what proxies are allowed to do

* headers tentatively added

* separate call and transaction state machines

* cancel/invite are separable
(will need to add note on need for timer in cancel, since you may
not get a 487)

* addition of spirals

* split spec in half - framework and methods draft

MIB Draft -- Dave Walker

Partition of MIB: SIP common, UA, Server (proxy and redirect), Registrar

Support modules: Added support for multiple instances in the same system,
throttling, some security things in there.

Wednesday Session
_______________

Message Waiting Indicator -- Rohan Mahy

Several issues were raised in discussion: 1) Should compare and contrast
with HTTP and poll models such as POP and with SNMP, asnwer "why these are
not suitable and SIP-MWI is". 2) A MWI is really just a presence information
bit, it might be more appropriate to just use the presence mechanisms, 3)
the alerting mechanism should be designed generically rather than
specifically as a voice-mail function.

SIP-H.323 requirements -- Radhika Roy

Point made -- this interworking is for basic call, not extra signaling like
Q.SIG. Also, IETF work should not address purely operational issues.

Call Flows -- Johnston

Several changes and corrections have been made.Multiproxy and transfer
additions needed. Caveat: this is  not a complete debug list, we probably
need to do some more work in that respect.

OSP Token -- Johnston and Thomas

consensus was to include it as a header
question: can you include a reference to the token instead of the actual
token?
Note: Proxies may read or insert but not modify tokens.
question: maybe recommend tcp since the tokens are large

DTMF -- Skip Cave and Bert Culpepper

Skip proposes that there are two problems - dtmf transport, readily covered
by RTP, and key input, which is a different problem. This is supported by a
historical analysis of the deployment of DTMF applications. Discussion
centered on solving the user input problem. Donovan proposed using
SUBSCRIBE/NOTIFY mechanisms to establish a signaling relationship for user
input. Question: do app servers need access to the RTP stream?

No conclusion

Emergency Services -- Henning Schulzrinne

Discussion centered on the applicability of SLP, with some contention..
Brian Rosen's note indicate that there was a consensus indicating that SLP
should be usable. Issues, however, extend beyond SIP -- for example,
emergency services for Web users?

Appliance Framwork -- Stan Moyer

No discussion allowed by chairs due to time constraints.

AAA Requirements -- Calhoun, etc.

Comments:Must take into account discussions in the AAA group.
Problem space must include use of services other than Internet Access logon.
Get discussion on sip rqmts onto the list

3rd Party Call Control with SDP preconditions -- Gonzalo Camarillo

No comments, two open issues will be taken to the list.

CC/PP exchange -- Iizuka

Comments:
This is similar, perhaps overlapping the caller preferences problem (Ed:
actually, it's the flip side of the same problem).
SIP may not be the right answer to this question -- or maybe we haven't
asked the right question yet.
This approach raises the question of whether the Guidelines should include a
direction for atomicity.

TIPHON work on SIP -- Sijben

No discussion due to time

SIP Firewall Policy mechanisms -- Jon Peterson

No discussion due to time

Call Control and Transfer -- Robert Sparks

Refer is not just for INVITES anymore. It has utilility in other methods.
Also, generalizing method to point to an arbitrary URL has interesting impli
cations.

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