Minutes, SIPPING WG, SIPish Interim Meeting 2004

Notes by Bill Marshall, Dean Willis, and Paul Kyzivat
Minutes edited by Gonzalo Camarillo
Meeting chaired by Gonzalo Camarillo, Rohan Mahy, and Dean Willis

SIPPING Session, Tuesday, May 25, 2004, 0900-1800

Topic: KPML
Slides presented: pres-dolly-sip-interim04-KPMLup-iss.ppt
Discussions led by: Martin Dolly

Issue: digit supression when interworking with H.323.
Conslusion: A small design group was assigned to discuss and report back.

Issue: Quarantine of digits before subscription.
Conclusion: a small design group was assigned to discuss the problem and report back.

Issue: get rid of EnterKey and OK expression, and add FlashHook and backspace.
Conclusion: only things which appear on keypads of analog PSTN telephone are in scope: 0-9, *#, flash hook, ABCD. Enter Key will be removed.

Issue: Multiple timers versus timer per expression
Conclusion: we stick to one timer per expression and add clarifying text in the draft.

Issue: MIME type for fileter in the SUBSCRIBE and for events in NOTIFY are different. Should they be merged together?
Conclusion: There seems to be a slight consensus that we will continue to maintain seperate MIME types at this time, but will also continue to consider the problem.

Issue: draft timing.
Conclusion: The author of app-interaction feels that it can be advanced concurrently, so we conclude to maintain the
normative dependency at this time.

Issue: Figure 3
Conclusion: It should be removed from the document.

Issue: add a sustained rate of no more than 100 NOTIFIES per minute.
Conclusion: OK, but need to state that overlapping NOTIFIES will happen.

Topic: GRUU
Slides presented: pres-rosenberg-sipping-interim04-gruu.ppt
Discussions led by: Jonathan Rosenberg

Issue: format of Instance ID is just a string now. We need to avoid conflicts across namespaces.
Proposal: what about using the technique of UUID URNs?
Conclusion: Jonathan will send a mail to the NID list asking about which namespace would be appropriate for Instance ID.

Issue: GRUU properties.
Conclusion: Temporal scope no longer makes sense, since same URI will be assigned when UA instance re-registers. If the registrar can identify a GRUU as one it generated (but not currently valid) then 410 or 480; if it didn’t generate the GRUU then 404.

Issue: administrative GRUU Creation
Conclusion: document administrative assignment as a means for GRUU construction, and scrub text to make sure there is not a registration bias (particularly the informative text regarding the UAS, e.g. section 5).

Issue: separate UI/Signaling Component – the UI (with Keypad) on one host, but the signaling handled on another host. The result of the list discussion was to require some kind of communication between the UI and signaling component in this case. 
Conclusion: Proposed that we ignore this case. No objections noted.

Issue: meaning of “Contact: *” with “Expires: 0”. 
Conclusion: it means to remove all registrations. No objections.

Issue: allow GRUU to work without instance ID, bound only to Contact URI
Conclusion: mandate a URI, not a URN.

Issue: allow a client to propose GRUU to the server.
Conclusion: don’t do this.

Issue: the suggested algorithm, which involves AES, yields long GRUUs
Conclusion: Jonathan will work some text using a hash in the registrar as another suggested algorithm.

Topic: Session Policies
Slides presented: pres-hilt-sipping-consider-policy-interim04.ppt and pres-mahy-session-policy.ppt
Discussions led by: Volker Hilt, Gonzalo Camarillo, and Rohan Mahy

Issue: Adopt the session independent policy draft as a WG item?
Conclusion: yes. The chairs will talk to the AD.

Conclusion: Concensus that both session specific/independent policies are needed.

Issue: which model do we choose for session-specific policies? Piggyback or Separate Channel?
Conclusion: A session policy use-case draft would be helpful. Very helpful. We should be able to extract use cases from every place that 3GPP has found it necessary to document SDP rewriting.

Issue: Response authentication. There appear to be issues in 3261 that allow for insertion of spoofed responses, even if TLS is used.
Conclusion: Cullen and Jonathan will work on addressing this in a 3261 addendum.

Topic: Exploders
Slides presented: pres-camarillo-sip-interim2004-exploders.ppt
Discussions led by: Gonzalo Camarillo

Issue: Address amplification issues.
Conclusion: Work on an opt-in mechanism with real-time removal.

Issue: Communicating the List, URI-Parameter vs only body.
Conclusion: the URI parameter has problems related to proxy translation, which make it an unsuitable solution.

Topic: Connected Party and Identiry
Slides presented:
Discussions led by: Jon Peterson

Issue: Header vs Body for Identity.
Conclusion: deferred.

Issue: how to know what happened when I called A but reached B. Two issues - Knowing it is B vs A, and knowing who caused B to be reached rather than A.
Conclusion: need further discussions.

Topic: Certificates and S/MIME
Slides presented: pres-jennings-sip-Interim-spr2004-Certs-v3.ppt
Discussions led by: Cullen Jennings

Issue: how to offer both RTP and SRTP.
Conclusion: need further discussions.

Topic: Dialog Package
Slides presented:
Discussions led by: Rohan Mahy

Issue: Issue: Hold. Does this need a callee-caps feature tag for interactivity?
Conclusion: How does this correlate to the "unable to send a BYE" property? Further discussions needed.