Subject: [Sip] Draft SIP Minutes for IETF 58

From: Dean Willis <[email-masked]>
Date: Thu, 13 Nov 2003 21:51:56 -0600

Please review the follwing and correct where needed.

Master copy posted at:
http://www.softarmor.com/sipwg/meets/ietf58/notes/minutes-sipwg-ietf58.html

Text follows:
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Draft Minutes, SIP WG, IETF 58
Official Scribe, Ben Campbell
Supplementary Scribe, Vijay Gurbani
Minutes Edited by Dean Willis

Topic: Call to Order and Agenda Bash
---------------------------------------

No issues raised.

Topic: Status, Chairs
---------------------

Slides presented.

New milestones proposed. No schedule objections raised, but it was 
proposed that the app-interaction framework be published as a proposed 
standard instead of BCP. Concerns about MIB status raised. Noted that 
SIP should certainly plan to operate at least through the current 
work-elevation plan from SIPPING, which extends through December 2004.
Topic: Congestion Safety,  Dean Willis
---------------------------------------
Reading list:
    draft-ietf-sip-congest-safe-02

There appears to be little interest in implementing this draft.  Some 
suggestions for simplifying it were made. It was also suggested that we 
need to change RFC 3263to prefer TCP over UDP, explain congestion issues 
and avoidance in a BCP, and complete the connection reuse work in order 
to encourage TCP deployment. Many endpoints now implement only UDP. We 
also need to differentiate fragmentation and congestion. It was noted 
that this problem does not just apply to MESSAGE, but can be frequently 
expected with NOTIFY, and with INVITES using S/MIME protection. DCCP is 
only a partial solution. Several people volunteered to work on this 
proposed BCP.

It was also suggested that the current draft could be simplified to 
eliminate new response codes 515 and 516, providing a minimal "NO UDP" 
assurance.

Topic: RFC 3312 Updates, Gonzalo Camarillo
Reading list:
     draft-camarillo-sip-rfc3312-update-00.txt

Slides presented.

Suggested that we adopt as WG item. No objections were raised.

Conclusion: adopt draft as wg item, negotiate milestone.

Topic: Publish, Aki Niemi
Reading List:
     draft-ietf-sip-publish-01

Slides presented.

Issue: Should etags be updated on every publish? Consensus: Usage should 
be made consistent with HTTP. If it cannot be, we should call these 
something else.

Issue: Publication rate. Proposed that rate from event package be used. 
Noted that this is probably an irrelevant and meaningless number, as 
there may be multiple publishers with no knowledge of each other. Much 
debate ensued, with no resolution  Further discussion deferred to the 
mailing list.

Topic:  Request History, Mary Barnes
Reading List:
     draft-ietf-sip-history-info-01
     draft-jennings-sip-voicemail-uri-00.txt
     RFC 3087

Slides presented.

Issue: r-uri captured anytime request is forwarded. Proposal: Only add 
reason for history entries added due to retargeting.

Issue: Privacy. Proposal: information not included when there are 
privacy considerations. (when uas sets session or header level privacy) .

Next steps: complete flow detail. Do we want to fold reqs into doc as 
front matter? Request more mailing list feedback. Dependency on mid-end 
security draft.
Presentation of applicability to voicemail.

Issue: Optionality. Suggested that we apply stronger language to suggest 
applications gracefully degrade in absence of history.

Issue: Implementability: Concerns raised by Robert Sparks, who will 
detail on mailing list.

Issue: Security. Note that this in-general seems to depend on the 
middle-to-end and end-to-middle security work.

Conclusion: Work should continue, but more thinking about optionality is 
needed. RJS and Mary to talk offline.

1400 Non-Invite Transactions,   Robert Sparks
Reading list:
     draft-sparks-sip-noninvite-01.txt

Slides presented.

Noted that this problem is not related to the transport protocol, but is 
specific to the SIP-layer transaction reliability mechanism for all 
transactions other than INVITE.

Several alternatives were presented:

A) a series of tweaks
B) Eliminate Timer F, allowing non-invite transactions to pend.
C) USe path-timing estimation techniques to improve UAs knowledge of timing.
D) Revise 3263 caching language to reduce severity of impact.
E) Ignore the problem

Suggested that SIP be revised to use 3-way handshake like INVITE on all 
transactions. This might be made backward-compatible through use of an 
option tag.

Polls indicated  no consensus on any action, and that the working group 
didn't understand the nature of problem or disagreed as to its severity. 
Despite the objections of Morton Thiokol engineers, the shuttle was 
launched in cold-weather conditions under which it had never been 
tested, and the O-rings in the boosters failed.

Conclusion: None. Further discussion deferred to the mailing list.

Topic: GRUU, Jonathan Rosenberg
Reading list:
     draft-rosenberg-sip-gruu-00.txt
     draft-rosenberg-sipping-gruu-reqs-01.txt

Slides presented.

Issue: GRUU generation for stateless proxy behavior. Consensus that we 
need a sample algorithm for understanding.

Issues: Liftime of a GRUU. Can a gruu change during a registration? 
Conclusion: No, gruu is good for lifetime of registrations, refreshes 
get same gruu.
Do we need a guarantee of difference between registrations? Probably no, 
discuss on list.

Issue: Dialog reuse—no longer a need with gruu. Should gruu spec 
deprecate dialog resuse if both peers support gruu? (Impacts refer, 
other subscribe usage).
Conclusion: Do not address in gruu spec, address in other drafts, put 
pressure on future work to avoid dialog resuse.

Issue: Does Gruu interferes with e2e signaling. UA can try to generate a 
local gruu, could use ice-like mechaninsm to decide if it is reachable. 
Propose to add to draft, but never try to put local address in contact 
header without using the mechanism.  Chair suggestion: Put statement 
about not using local gruu in gruu draft, put “iceing” in separate 
draft. Author agreed.

Issue:  MUST NOT use locally generated gruu is too strong. Clarified 
that definition of local gruu is one with a different domain part than 
AoR, MUST does not apply to the examples given.

Topic: Join,  Rohan Mahy
Reading List:
     draft-ietf-sip-join-02.txt

Slides presented.

Noted that no comments in wglc. Room shows interest, but no one has 
implemented.
We want more list discussion before sending to IESG.

Topic: REFER Semantics, Rohan Mahy
Reading List:
     draft-olson-sipping-refer-extensions
     draft-mahy-sip-remote-cc

Slides presented.

Basic premise is that the semantics of  the various uses of REFER are 
under-specified. Much discussion ensued.

Issue: Is this equivalent to specifying fixed services? If we have to 
specify all the services/features, then the refer approach has failed.

Issue: How do you put refer requests in a context? Dialog reuse? 
Separate GRUUs? Explicit refer-to header parameters?  Noted that it may 
require per-scheme semantics in addition to context.

Issue: Need more than context—how do you know what an endpoint will do 
with a particular URI scheme?

Issue: Not useful for authorization, because referee cannot decide if 
issuing the request could be bad. Another motivation that is relevant is 
to determine how to render the UI for the action.

Sugested: this does not mean fixing refer, it means adding something new 
to it.

Discussion on proceeding: How do we proceed? Refer for other than 
transfer unlikely to work on today’s UAs. Rohan suggests defining 
semantics for baskets of functionality. Use option tags to make sure 
they are supported. Propose explicit dialog parameters for refer-to. 
Provide guidance for remote call control vs. remote UI invocation.

No conclusion, further discussion deferred to list. Interested parties 
are to contact Rohan and work on it.

Final To-Do:
-------------

App Interaction Framework -- change from BCP to PS.
Add milestone for RFC 3312 update as PS.
Discuss publication rate on mailing list.

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