Last Modified: 2003-01-27
1. Documenting the requirements of specific chartered tasks.
2. Documenting the usage of SIP to solve real problems that need to be solved in a standardized way.
3. Looking for commonalities among the chartered tasks and other ongoing SIP-related development, as commonalities may indicate need for general, reusable functionality in SIP.
4. Describing the requirements for any extension determined to be needed, and handing them to the SIP WG.
5. Develop procedures and requirements for configuration and delivery of SIP User Profiles
Besides performing needed specification of several applications of SIP, SIPPING can be seen as also working out use cases that clarify the role of SIP in the Internet, and help to ensure that Occam's razor is appropriately applied to SIP usage.
The security of all the deliverables will be of special importance. The technology for security will be keyed from a SIP security specification developed (in progress now) by the SIP Working Group.
The specific tasks for SIPPING will be:
1. PSTN and/or 3G telephony-equivalent applications that need a standardized approach
- informational guide to common call flows
- support for T.38 fax
- requirements from 3GPP for SIP usage
- framework of SIP for telephony (SIP-T)
- call transfer and call forwarding
- AAA application in SIP telephony
- mapping between SIP and ISUP
2. Messaging-like applications of SIP -
- support for hearing-/speech-impaired calling
- development of usage guidelines for subscribe-notify (RFC 2848, SIP events) to ensure commonality among applications using them, including SIMPLE WG's instant messaging.
3. Multi-party applications of SIP
- the working group will review a number of technical pieces including call transfer, subscribe-notify, SIP features negotiation, and session description protocol (SDP) capability negotiation, and will develop requirements and an initial design or framework for multi-party conferencing with SIP.
4. SIP calling to media servers
- the working group will develop a requirements draft for an approach to SIP interaction with media servers. An example is whether a voicemail server is just a box that a caller can send an INVITE to.
At a later time, the working group and chairs may request of the Area Directors that new tasks be added to the charter. Such additions to the charter will require IESG approval.
The group will work very closely with SIP working group. The group will also maintain open dialogue with the IPTEL working group, whose Call Processing Language (CPL) related to the task areas in a number of ways. The group will also coordinate closely with SIMPLE, AAA, and MMUSIC (SDP development).
SIPPING will also ensure compatibility with the work done by the now concluded PINT working group. SIPPING will encourage active participation from the Distributed Call Signaling (DCS) Group of the PacketCable Consortium for distributed telephony services, 3GPP, 3GPP2, and several ITU-T study groups.
|Done||Submit Internet-Draft on SIP-Telephony Framework to IESG for consideration as a BCP|
|Done||Submit Internet-Draft on ISUP-SIP Mapping to IESG for consideration as Proposed Standard|
|Done||Submit Internet-Draft on Requirements for use of SIP to support telephony for the Hearing-Impaired to IESG for consideration as an Informational RFC|
|Done||Submit SIP 3rd party call control to IESG for consideration as BCP|
|Done||Submit Internet-Draft on 3G Requirements to IESG for consideration as an Informational RFC|
|Done||Submit Internet-Draft on Mapping ISUP Overlap Signaling to SIP to IESG for consideration as a Proposed Standard|
|Done||Submit Internet-Draft on Usage Guideline for Events (Subscribe-Notify) to IESG for consideration as an Informational RFC|
|Done||Submit Internet-Drafts Basic and PSTN Call Flows to IESG fro consideration as BCPs|
|DEC 02||Requirements for Content Indirection in SIP|
|FEB 03||Submit Message Waiting SIP event package to IESG for consideration as PS|
|MAR 03||Submit Internet-Draft on Call Transfer using REFER to IESG for consideration as a BCP|
|MAR 03||Using ENUM with SIP Applications to IESG for consideration as an Informational RFC|
|APR 03||Submit Call Info SIP event package to IESG for consideration as PS|
|APR 03||Requirements for Reuse of Connections in SIP|
|JUN 03||Submit Internet-Draft on T.38 Fax Call Flows to IESG for consideration as a BCP|
|JUN 03||Submit Conf Info SIP event package to IESG for consideration as PS|
|JUN 03||Requirements for SIP Request History|
|JUN 03||Event Package for User Configuration Profiles|
|AUG 03||Submit Internet-Draft on Multi-Party/Conferencing Framework to IESG for consideration as an Informational RFC|
|AUG 03||Submit Internet-Draft on Requirements for AAA Application in SIP Telephony to IESG for consideration as an Informational RFC|
|OCT 03||Sip Interworking with QSIG|
|NOV 03||Review charter with Area Directors and recharter or conclude|
|NOV 03||Submit Internet-Draft Torture Tests to IESG for Consideration as Informational|
|RFC3351||I||User Requirements for the Session Initiation Protocol (SIP) in Support of Deaf, Hard of Hearing and Speech-impaired individuals|
|RFC3372||BCP||Session Initiation Protocol (SIP) for Telephones (SIP-T): Context and Architectures|
|RFC3324||I||Short Term Requirements for Network Asserted Identity|
|RFC3398||PS||Integrated Services Digital Network (ISDN) User Part (ISUP) to Session Initiation Protocol (SIP) Mapping|
Minutes, SIPPING Working Group, IETF 56 edited by Dean Willis Session 1, Monday March 1700, 1930-2200 Scribe: Vijay Gurbani, Mary Barnes Chat coordinator: Al with the Hat Chairs called meeting to order. Agenda agreed as: 1930 Agenda Bash 1935 Status -- Chairs Call Control Issues 1945 Service Examples, Alan Johnston draft-ietf-sipping-service-examples-04.txt 1955 Call Control -- Transfer, Allan Johnston draft-ietf-sipping-cc-transfer-01.txt 2005 Caller Preferences Use cases, Jonathan Rosenberg draft-rosenberg-sipping-callerprefs-usecases-00.txt NAT and Policy Issues 2015 Persistent Connection Management Requirements, Vijay K. Gurbani draft-jain-sipping-persistent-conn-reqs-00.txt draft-ietf-sipping-connect-reuse-reqs-00.txt 2035 SIP Network Address Translation, Jonathan Rosenberg draft-ietf-sipping-nat-scenarios-00.txt draft-rosenberg-sipping-ice-00.txt 2045 Session Policy Requiments, Jonathan Rosenberg draft-rosenberg-sipping-session-policy-00.txt 2055 URI Leasing, Jonathan Rosenberg draft-rosenberg-sipping-lease-00.txt Design Teams 2105 SIP Conferencing Design Team, Alan Johnston Web Page for the Design Team 2135 Application Server Interaction Design Team, Jonathan Rosenberg Web Page for the Design Team 2140 Transcoding Design Team, Gonzalo Camarillo Web Page for the Design Team 2145 Emergency Calls Design Team, Jon Peterson Web Page for the Design Team 2150 Limiting Notifications Rate, Aki Niemi draft-niemi-sipping-event-throttle-reqs-01.txt 2200 Wrap Topic: Service Examples, Alan Johnston Moving well. Author wishes to add some text discussing how to implement some servcies and discussing trade-offs and expects that draft will be complete before next meeting Topic: cc-transfer, Alan Johnston Slides presented, included in proceedings. This version had few changes: added a section on use of Referred-By header. Added selected message details. Added many more call flows on attended transfer and unattended transfer. Added a security consideration section. No known open issues with the I-D. Group polled on readiness for WGLC: No objections noted. Audience asked if there was any overlap or dependency on globally-routable contact URI work. Author belives there is currently no dependency, but that if the GRURI work completes, it would be nice to reference it from this draft. Topic: Status report: Chairs Slides presented, included in proceedings. We have 3 RFCs which have been published, considering the amount of work we had on our plate. 2 on IESG queue; bunch of individual I-D. 3 in here that are ready for WGLC. A lot of work is blocked on other stuff -- call control, ICE, work going on in midcom, etc. Note chairs believe that formal expert review is not required for all individual drafts. Current policy is to announce the draft to the list, and ask the participantst to verify that the draft does not conflict with WG efforts. Under the current process, we do a formal expert review for P-headers or when asked to do so by IESG/ADs. It may be useful for us to split things into smaller groups -- some I-Ds document usage of SIP, others talk about services (cc-conferening, cc-transfer). It may be appropriate to let some of this work proceed without supervision of the WG. We may end up doing this in Vienna in order to get up to speed. Will like to get comments on the mailing list or after session on if this is okay. Topic: Caller-Preferences Use Cases, Jonathan Rosenberg Slides presented, included in proceedings. Poll: Useful, interest in accepting as WG document? Strong consensus recorded. AD suggested that these use cases be packaged with CallerPrefs drafts. Topic: ICE, Jonathan Rosenberg Slides presented, included in proceedings. Provides general methodology for using address-fixing protocols to get SIP through NAT. Question: What is the impact if some sort of underlying mobility function causes node address changes? Does ICE resolve? Ans: Unknown, but we think it should work if the frequency of address changes is lower than 1/RTT. Question: Does having STUN server on every node open up the network to denial-of-service attacks on NAT translation? Ans: No -- at least, no more than port-scanning already would. Poll: Who read: fairly large number. Question: Muxing STUN and media -- is that required? What is the implication of demux? Ans: It seems to be feasible to use magic-cookies in the TUN level to work it out. Comment: This DOES require widespread deployment to be useful, can we get that? Ans: If it works, people will implement it. Question: What are implications if only one end supports? Ans: We fall back to what we have now. Question: IS it easier to fix the NAT than to fix the SIP? Ans. Debatable. There's a lot of $39 NAT boxes out there. Poll: How many people would be interested in implementing? (several) Will one volunteer to write the preconditions (document things like like SDP changes, requirements in SIPPING) Yes-- Cullen Jennings. Poll: Would you like this work to be documented in SIPPING, along with fallback to previous modes? Ans: Loud response, a few dissenters. Proposal: Cullen to work on preconditions, Jonathan to work on furthering ICE draft, WG to request authorization to pursue as WG effort. Topic: Session Policy Requirements, Jonathan Rosenberg Slides presented, included in proceedings. Slides presented reviewed scenarios. Poll: Do we want to work on this? Brian Rosen reports that he really needs this for dealing with 6Mb/s streams and managing admissions policy dynamically. Another comment made that this approach could obviate the need for some B2BUAs. Comment that we should add requirements to do this without "new headers" and it shoud work with e2e encryption (req #1 in presentation). Poll: who thinks we should take this work on as a baseline for requirements? Strong consensus reported, none opposed. What happens when a service provider wants to insist on some aspects of a session (media flows through a realy, video not be used, etc.) So far this has been done with SDP modification. Well known problems: does not work with data encryption, requires proxies to have knowledge of session descriptions, proxy complexity increases, ... Solution: 3GPP does this -- they use 488 as a response code to list codecs which are acceptable. This has some drawbacks as well. Do we want to work on this problem? That is the real issue for us to decide now. Many people approached the mic and agreed to the requirements being valid. Keith Drage suggested that we resolve the requirements before proceeding with a solution, and that consideration of various solutions (such as Jonathan's proposal) should be deferred until the requirements are agreed. Poll: who thinks we should take this work on as a baseline for requirements? Strong consensus reported, none opposed. Chairs will request approval as a WG item from ADs. Topic: URI Leasing, Jonathan Rosenberg Slides presented, included in proceedings. Material introduced from slides. Question: This allows for temporally scoped URIs. Can we give an example of where this would be useful? Ans. Assume a conference call running over a set time. Discussion that current document may be a bit complex in this area. The word "temporal" is probably misapplied in this context and the author would like to withdraw it. This all comes down to embedded route headers vs. a lease-and-preference model. Perhaps we need to step up a level and ask what the top-level requirements really are? The draft proposes three explicit. There may be also "without hiding state in the domain name" and some others. Comment: Leasing seems to imply temporal scoping. Huh? Long discussion . . . Comment: It seems that all of the given requirements could be met by relaxing a single restriction in 3261. Conclusion: More list discussion on requirements needed. Topic: App Interaction Design Team, Jonathan Rosenberg Slides presented, included in proceedings. Minimal activity since last meeting. We should develop use cases illustrating the requirements. Jonathan Rosenberg requested that proposed use cases be sent to him via email. Topic: Persistent Connections, Vijay Gurbani Slides presented included in proceedings. Basics presented. Discussion ensued. Question: What is the requirement difference between signaled persistence and simply configuring persistence? Assertion: Reuse is only important in the client-server case. Assertion: This sounds like my kids discussing bedtime. There is really only reason to close a TCP connection -- to recover resources. Therefore, the interesting thing, is not how do connections come up, but figuring out which connection to kill if we need to kill one. Assertion: the mechanism here is equivalent to "just doing the right thing" with TCP, so we should fix it operationally, not by changing the protocol. Poll: Should we change the SIP spec to encourage leaving TCP connections open unless they need to be closed? Strong consensus reported. Proposed that we do minimal bug fixes in SIP, and do a separate document with an operational focus on "how to" reuse TCP, initially as a discussion and possibly leading into a BCP. No objections noted. Vijay Gurbani may volunteer to lead on a usage document. Topic: Conferencing Design Team, Alan Johnstson Requirements, Framework, and Call Control ready for WG adoption. Conference Policy is splitting into two and should be ready shortly. Media policies work requirements progressing, work on policy manipulation is ongoing, and the policy work needs a new home. MMUSIC is not going to adopt this in their new charter. Question: This policy work is related to data manipulation in SIMPLE, can we combine it? Ans: Probably not. One is data manipulation, the other is policy RPC. Open issues recapped in slides. Discussion of absolute vs. relative time in focus. Why not have absolute time? Ans. Simplifies timeing coordination on focus. Comment: We do have requirements for realtime transitional controls for things like camera-follows-speaker. SOAP and ACAP don't combine to meet this requirement. Ans: This is for more persistent policy, not floor-control. Floor-control remains a media problem. Poll: Do we wish to, as proposed, adopt the requirements, framework, and call control drafts as wg efforts? Strong consensus, no objections. Question: Is discovery in-scope? It could be a furball. Request: Make focus migration happen sooner rather than later. This will be required for three-way to more-way migrations. This is also important from a fault recovery standpoint. The call-control is easy, just a REFER series, but handling the policy migration is more interesting. Discussion: Policy group needs working group home. Rohan: mmusic will NOT be chartered to do this; so it is either us or a new BOF. Will work it out with the ADs later. We have not been told that we have to stop working on this. Open issues: conference policy protocol, floor control, notifications. Proposed: Adopt Reqs, framework, and call control I-Ds as WG documents. Poll taken, and strong consensus reported. Open reqs: discovery, focus role migration, cascading and camera control. Topic: Hearing impaired media transcoding, Gonzalo Camarillo Work proceeding, no surprises. Author reports little progresssince last IETF and believes that now that we have media policy I-D and session policy reqs, we will make more progress for the next IETF. Topic: Emergency calling design team, Jon Peterson Work proceeding, will try to have face-to-face meeting here. Two cases -- regular 911 calls, and PSAP access-link replacement. Can we divide these two cases so that there is something available for "today's PSTN PSAP"? Topic: Event Throttling Requirements, Aki Niemi Notification rate limiting is the "common factor" among most of the event filtering discussions. Issues: Is the model accurate and appropriate? Do we need both the leaky bucket and the strict throttle? Is it ok to leave handling of quarantined notifications out of scope? Is this work useful? Discussion: It may be important to have a different throttling mechanism for "aggregated/filtered" notifications than for simply prioritized or decimated notifications. The current work does not really consider notification volume/size, just counts. Discussion about the difference between quarantine and gating/throttling functions. One can define a five-token multibucket scenario that's fairly complete. Is this too complicated to be practical? Volutneers to review reqs -- Jonathan, David Oran, and Tomn Taylor volunttered. Poll for adoption: none opposed. Question: Is there standardization required to be able to rate limit? Event Throttle Requirements, Aki Niemi Aki went through the model and the requirements (see slides). Issues: Is the model accurate and appropriate? Do we need both leaky-bucket and the strict throttle models, or is only one of them enough? Observation from floor: Quarantining and throttling are not the same thing. One introduces delay the other control rates. Rohan: Jonathan, Dave Oran and Dean will review the I-D and the WG will receive an update from them before this becomes a WG document. Session 2, Wednesday March 19, 1530-1730: Scribes: Paul Kyzivat, Vijay Gurbani Chat coordinator: Brian Rosen Session called to-order by chairs. Agenda agreed as follows: 1530 Agenda Bash Security Related Issues 1535 Role-based Authorization Requirements, Jon Peterson draft-peterson-sipping-role-authz-00.txt 1545 Request History, Mary Barnes draft-ietf-sipping-req-history-02.txt draft-barnes-sipping-history-info-02.txt Operations 1605 SIP Endpoint Service Charging Requirements, Wolfgang Beck draft-beck-sipping-svc-charging-req-01.txt 1615 SIP User Agent Configuration - Dan Petrie draft-ietf-sipping-config-framework-00.txt 1625 Issues in Dual Stack Environments, Hakan Persson draft-persson-sipping-sip-issues-dual-stack-00.txt 1635 SIP-AAA Requirements, Gonzalo Camarillo draft-ietf-sipping-aaa-req-02.txt Media Related Issues 1645 Early Media, Gonzalo Camarillo draft-camarillo-sipping-early-media-01.txt 1710 Network Announcements, Eric Burger draft-burger-sipping-netann-05.txt 1720 Considerations on the IPREP Requirements, Jon Peterson draft-peterson-sipping-ieprep-00.txt 1730 Wrap Topic: Role-Based Authentication, Jon Peterson Slides introduce concept. Question: Can you show some use cases? Assume two previously unassociated carriers in a federation wish to exchange calls. One carrier issues an authorization object, which the caller hands to the other carrier, allowing the call to proceed. Other examples followed. Discussion from floor: Are we proposing replacing identity with roles? Jon responded that this could encompass identity, but maybe not. suggested from floor that we add more in doc explaining relationship between identity and roles, agreed to by author. Request: Somebody asked for more use cases. Was also concerned whether all stated requirements were self consistent. Observation from floor: Jiri Kuthan suggested that this was a replacement/alternative for network asserted identity. Observation from floor: Somebody suggested that Role wasnt exactly the right term to use. Topic: Request History Rqmts and Solution, Mary Barnes Slides presented, included in proceedings. Mary Barnes presented current status of both documents. Both requirements and solution have had two new versions since last meeting, now up to -02. Mary explained changes. Of note - separating out security requirements, to separate document. Remaining open issue is security, which is work-in-progress, which a seperate security solution draft expected soon. Consensus that requirements document is roughly complete and should be referred to SIP WG for action. Chairs need to refer to AD for approval. Topic: SIP Endpoint Service Charging Requirements, Wolfgang Beck Slides presented included in proceedings. Introduces requirements and a model for third-party trust assignment with SIP. Possibly combinable with role-based-authorization. Proposal: this should be two drafts, one around charging and another about advice-of-charge. Comment: this seems to be limited to a fixedSIP architecture as currently written. Comment: the evaluation of the requirements presented in the draft would be greatly aided by the inclusion of use cases. Comment: reading the document indicates a specific business model in-mind. Work here should be network agnostic and not make assumptions about who is paying (like caller always pays) etc. Question from chairs: Are we interested in trying to gather requirements to support an endpoint based charging model (i.e., not billing from intermediaries). Consensus that we would like to see the work more completely illustrated, including use cases, before considering its utility. Topic: Config Framework, Dan Petrie Slides presented included in proceedings. Open Question: Should HTTPS be a SHOULD or MUST strength reequirement: Ans. MUST implement, SHOULD use. Open Question: Is HTTPish preferred to LDAP or ACAP? Open Question: Is this related to NETCONF work? Discussion: There are issues here that cannot be fixed with HTTPS pixie dust. You need a separate mechanism of top of HTTPS to verify the identity of the node requesting configuration. Of course, this needs to be configured in. So there is a bootstrapping problem. Open question: device identity parameters: User-agent header? New header? No decision made. Open question: How to indicate profile type? Accept-header or event header parameter or request-URI? Comment: this is the same problem as SIMPLE's buddy list management and should use the same mechanism. Further discussion taken to the list. Dan Petrie presented. Identified changes from prior version. (draft-petrie-sipping-config-framework-00) There were comments about strength of use for HTTPS for content indirection in here. General sentiment seemed to be that HTTPS should be MUST implement, SHOULD use. Other protocols other than http/https are also possible. Henning Schulzrinne said https isnt enough. Said there were both confidentiality issues as well as way to ensure the client gets the right data. In absence of client cert, which you cant assume during config, presents difficult problems how to bootstrap. Dan acknowledged this problem, and said he has already proposed to do work to deal with that. Further discussion went on. Rohan asked that this go to list. Dan requested input on list for where device identification should go in User-Agent header or somewhere else. Discussion of profile type where to indicate in subscription. Jonathan Rosenberg thought you could subscribe to a different request uri for each kind of thing. Rohan Mahy disagreed. Was sent to the list for discussion. Jonathan suggested this is similar to SIMPLE problem regarding buddylists, and the two works should be synchronized. Topic: Dual-Stack Issues, Hakan Persson Slides introduce problem and recaps several solutions. The "contact" problem seems to be addressable in part by dual-interfaced record-route and in part by ICE. The document will be revisited by the author exlporing usage of these techniques and, if the solution is satisfactory, can become a usage document illustrating the solution to the problems it has already raised. Topic: AAA Req, Gonzalo Camarillo Slides presented included in proceedings. Currently in WGLC. Poll: Any issues that have been missed? No new issues. Attendees encouraged to follw WGLC. Topic: Early Media, Gonzalo Camarillo Slides presented included in proceedings. Open issues: There appear to be three ringback states from ISUP, and only two codes (180, 183) available in SIP. Not all protagonists are present and the author proposes to hold a conference call for resolution. Debate ensued anyhow, trying to capture essence of the issue. Francois, Flemming, Rohan, others agreed to send use cases illustrating the issues they need solved. Poll: should we add a flag? No clear consensus Topic: Network Announcements, Eric Burger Slides presented included in proceedings. Open Issue: Media on Hold? What does a media server do when it gets put on hold? This seems to be application specific, not a SIP protocol problem. Open Issue: 409 Result code proposal? Suggestion from audience Can we TRY not to use things that are used in HTTP to mean something different? Sugggestion: Could we use a standard response code and a Reason field? Conversation deferred to list with emphasis on 6xx vs 4xx debate. Open Issue: Multiple Media Streams:? What do do then, to play multiple things? Eric asserted this isnt an issue if the target uri is a composite object. He wanted to know if that is the predominant use case. And if not, how would the multiple streams be synced? Brian Rosen wondered why it isnt good enough to pick one stream. Confusion reigns, deferred to list. Open issue: IS everything in this draft consistent with WG usage? We need to be sure we're aligned with conferencing and early media work? Author asked to work with Alan Johnston on conferencing alignment, and Gonzalo Camarillo on early media. Topic: IEPREP Considerations, Jon Peterson SIPPING asked to provide formal response to the IEPREP considerations, widely discussed on mailing list. Open Issue: SHOULD we address this here? As there is already work in SIP on the priority header? Should we do it here? Discussion: Jon Peterson presented. Said this work was in response to requests by area directors for comments on RFC3478. This is Jons private attempt at comments, based on some discussion on list. Jon raised privacy issues. Henning said there are fundamental tradeoffs between privacy and proxies, and that therefore it is necessary to offer endpoint with options for either. Keith Drage asserted that either there is an error in the IEPREP requirements that ought to be fixed there, or else it should be dealt with by SIP in responding to the requirements, so there is no need for SIPPING draft in this instance. Allison Mankin agreed, said the area directors could deal with this aspect now, and dont need any more input. Rohan observed that SIP already adopted a mechanism that relates to this. : Meeting concluded.