Subject: [Sipping] Notes, 2nd SIPPING Session

From: "Dean Willis" <[email-masked]>
Date: Thu, 21 Mar 2002 11:19:46 -0600

The following are my rough notes from the 2nd SIPPING session. Please
review and get back to me with any corrections needed.

--------------------------------------------------------------

SIPPING Meeting Ietf 53, Session 2 21Mar02
Recorded by Dean Willis

Agenda Bash:

* No Issues

Accounting/AAA Systems, Bernard Aboba:

    Slides describe requirements of real-world accounting
    requirements, including reliability, security, current issues with
    RADIUS.

    Current issues with RADIUS include:

	- backoff unspecified
	- failover unspecified
	- application layer acknowledgement missing
	- undefined proxy behavior
	- no error messages prevent intelligent failure response
	- transport security has no confidentiality, known attacks
	- replay protection only in post-processing
	- no object security, MITM open

    Alternatives discussed including SNMP, DIAMETER
    
    Question: Why couldn't we use Web Services model and XML over
    secure transport? Answer: accounting semantics are undefined. It
    could be done, but hasn't yet.

    Chair: We had this conversation in order to help us understand
    AAA requirements.

    Question: There are existing systems usually in place
    (RADIUS). Why are we being blocked from working with them?

    Proposal from chairs: Should we be able to do capacity planning
    and non-usage senstive billing? Consensus yes. Is time sensitive
    billing in scope? Chair's

    Question: We have real requirements -- why are we arguing about
    which grid-box from RFC 2975 we're going to try and fill?
     
    Question: Time-sensitive billing is a requirement from 3G. Whether
    it is interdomain is option. Are we talking about the other two
    A's?
    
    Comment: We should at least consider what has been accomplished with
    a non-IETF protocol in real-world billing systems.

    Question: DIAMETER seems to be the implicit assumption. RADIUS may
    be obsolete, but should we, instead of arguing requirements, just
    do a standards-track spec for using DIAMETER and an informational
    track for using one or more of the existing protocols like RADIUS?
    Allison: There will be resistance to any RADIUS solution on an RFC
    track. Why not just use SNMPv3? Chair comment that that doesn't
    appear to be a good fit for people are doing.

    Question: When will DIAMETER exist? Spec editor reports that major
    issues are done, a few editorial and security considerations
    remain for documentation, otherwise ready to go.

    Observation: RADIUS is widely deployed in accounting for dialup
    internet access. Many providers combine dial=up with VoIP and have
    incentive to use same accounting infrastructure. It would be
    useful for us to document any vulnerabilities of RADIUS that apply
    to SIP that did not apply to dialup. Response: If you're doing
    dialup, you're probably not in usage sensitive billing or at least
    don't have the same requirements as VoIP.

    Comment: It is clear that we are driving while looking in
    rear-view mirror, trying to retrofit VoIP billing on RADIUS. It is
    clear that we have to look at record format (XML), secure
    transport (TLS), and look forward instead of backward.

    Comment: We should keep in mind that we have a lot of work to do
    with things like record transfer and post-processing stuff
    indepedendent of record formats and the like.

Other DCS Drafts:

  draft-scsgroup-sip-proxy-proxy-06.txt:

    Slides report status and background. Need to update for sipchange
    process as ind. informational (P-header, no options tag)

  DCS architecture draft:

    Slides report status. Similar sipchange issues.

    Chairs poll for reading of drafts, and for concerns on informational
    publishing. Comment that we need to know if there are any
intellectual
    property claims, answer "probably".

    Question? Will we apply sipchange? yes.

    Poll for consensus to proceed -- no objections raised.

Report on 3GPP Ad-Hoc from 20Mar02 (Miguel Garcia):

    Path header: current two drafts seem reasonable.

    Privacy: Several problems, no clear resolution yet.

    Dialed URL: (Target Address-of-Record): P-header approach seems
    feasible in the short term, may be able to use history or other
    mechanism in the future. EdNote: This could also be considered
    as something like a "display name" for the request-URI.

    3GPP XML Body: Moving most content to P-headers. 

    Security items as resolved in SIP.

Event Packages Procedure (Rohan Mahy):

    Chairs: Do we need a seperate guidelones document for the authors
    of SIP Events?

    Question: Do we have a template that somebody to use to pre-screen
    their work for completeness? ENUM put together a template for
    service field definition. Is the stuff in the sip-events RFC
    adequate? Chairs poll for sufficiency: strong consensus, current
    guidance is adequate.

Call and Conference Package (Jonathan Rosenberg):

    Slides review proposal from drafts and changes including examples,
    bis-alignment, addition of direction attribute, removal of To-
    headers in favor of explicit coding, removal of floor control.

    Next steps: at least one implementation known. Need to make sure
    scope is right and data formats have all information we need. Will
    split document into two packages (dialog and conference). Propose
    adding this effort as SIPPING WG item. 

    Comment: AS we start dfining XML event packages, it looks like the
    world has moved on beyond DTD definitions into schema-based
    definitions. We should make a similar evolution in schema
    definition. Chairs: This is reasonable. 

    Comment: This framework is needed for distributed call control and
    the work is supported by the speaker. Several confirmiong comments
    made. 

    Comment from chair (Rosen): Do we want to do this definition in
    SIPPING or is this something that should be done in SIP? This is a
    "piece" of the problem. It would be really nice to have a bigger
    view. Have we finished the requirements? Response: It's nice to
    understand big picture, but also nice to make incremental
    progress. Chair (Mahy) we need to follow procedure, but we have
    some requirements, can we proceed? Author: It would be nice to
    have some discussion of requirements on data format. This should
    be reflected oe-to-one in the result document, so can be done in
    conjunction instead of as a seperate effort. This is really a
    "piece of framework". General discussion follows. Poll for
    call-info package, none opposed. Poll for conference info package:
    none opposed.

Future Work (chairs):

    Proposals in slides.

    3PCC BCP: Never an extension because it was doable in straight
    SIP, mostly. This has been greatly improved in bis with o/a and
    update. So the proposed work is to discuss aquestionable lternatives
and
    recommend best practices from the known alternatives. This is not
    intended to say that 3PCC itself is a better practice than
    distributed. Poll for adoption: no objections.

    Message waiting: Poll for adoption as WG item: no
    objections. Question: package seems to want to do more than voice
    message waiting. Author response: will adjust to workgroup
    conesnsus. Question: Where do we document interworking this with
    ISDN?

    Content indirection and reason codes: Will continue requirements
    development.

    Opaque URI usage: Proposal to do informational draft on guidelines
    for use of opaque URIs.

    MSURI draft: Propose to either roll into Opaque URI or publish as
    individual informational or do as WG effort. Comment: We haven't
    really as a group figured out how to do this osrt of thing. Would
    like to see something that steps back, looks at broad
    requirements, before delving into solutions. The usage of URIs as
    service indicators is one of the biggest archittectural problems
    we face. Counter: This is too large an approach, and we need a
    solution today. Comment: It is important to define a framework for
    discovery. Comment: Unless there is someone pushing to do this
    analysis, the result is likely useless. It is better to proceed by
    just applowing people to document different approaches and label
    them with applicability statements. We don't know how big the
    problem space is, and it is likely to be very large. Comment: we
    need to define a schema. Comment: we need to do requirements, not
    jump into solutions. Comment: we need services, concern that if we
    stall on URI conventions that we'll have problems. Eric Burger
    volunteers to do framework. Comment: Suggest researching
    requirements and publishing msuri as an individual in the
    meantime. Chair comment: would like to see framework or
    requirements first. Poll: SIPPING WG to develop guideline document
    on use of URIs. Result - one opposed.

    SIP VXML: 

    NAT Scenarios Draft: Should we do it as WG efforts? Comment:
    Dealing with NATS is an enormous tarpit. There are many options
    that apply to different scenarios. Discussion on scope
    follows. Comments: it would be good to bidirectionally align this
    with the "unsafe" framework document. Poll: Adopt this as wg item
    leading to informational rfc: None opposed.

Emergency Services Discussion (Mike Pierce):

    Slides review status of emergency services draft and relation to
    IEPREP work.  Proposal from chair: Can authors work with authors
    of resource priority header on SIP requirements and move other
    work to ieprep? Answer: That is how the authors are currently
    proceeding.

Open Mic:

    How do we deal with the approval policy for 3PCC stuff like
    accepting REFERs, etc. Ans: should be in usage drafts, in ot send
    text.

    Device Requirements: We didn't get to this the other day. Where do
    we stand on it? Comment: There has been some discussion that there
    may be other venues for operational discussions, such as SIP
    forums. Comment: Ideal world would be: IETF realized long ago that
    device configuration is a problem that will be universally faced
    and have developed a "plug-in" framework (like MIBs) for doing
    so. This didn't happen. Comment: discussed taking current config
    document and adding discussion and applicability of things like
    SNMP, ACAP, etc. Comment: The OAM area has committed to reading
    the document and working with the author and other interested
    parties. Comment: This is "right now" problem. We have all the
    tools we need. We need to write down an interop doc. Comment: We
    have a split between framework and content. Can we go forward with
    the definition of the data indpendent of the delivery mechanism?
    Request from chair: Can we continue this as individual work,
    dicsussed on SIPPING list, until more clarity?. No
    opposition. Comment: SIP end devices aree a whole industry,
    managed by housewives to sysadmins with massive systems. Please
    think about it.

    Settlement: Idea to generate discussion. There might be an
    opportunity to define a generic challenge-response settlement
    architecture framework. Comment: How about a response code that
    says "Payment required -- here's an invoice" something like a
    401/407 challenge, with the re-INVITE to contain payment
    information. Comment: This screams for requirements development in
    the SIPPING process, need to scope the problem, describe some
    scenarios, and send text.

    AAA: Earlier presentation did not explore large solution space now
    available. What we can we do if we bring in web services and
    similar technologies? Consider reviving interdomain settlement/osp
    drafts earlier "out of scoped" in SIP. Chair request: List
    discussion on proposal and approach -- "how can we get something
    done within IETF?" Question: Do you see this work diverging into
    user-service/provider and provider/provider channels? Response:
    Mostly between providers. The important thing is the trust
    function or clearinghouse that enables any-any business
    relationships.

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