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Versions: (draft-petrie-sipping-config-framework) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 RFC 6080

SIPPING                                                        D. Petrie
Internet-Draft                                             Pingtel Corp.
Expires: April 21, 2004                                 October 22, 2003


            A Framework for SIP User Agent Profile Delivery
               draft-ietf-sipping-config-framework-01.txt

Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups. Note that other
   groups may also distribute working documents as Internet-Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time. It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at http://
   www.ietf.org/ietf/1id-abstracts.txt.

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.

   This Internet-Draft will expire on April 21, 2004.

Copyright Notice

   Copyright (C) The Internet Society (2003). All Rights Reserved.

Abstract

   This document defines the application of a set of protocols for
   providing profile data to SIP user agents.  The objective is to
   define a means for automatically providing profile data a user agent
   needs to be functional without user or administrative intervention.
   The framework for discovery, delivery, notification and updates of
   user agent profile data is defined here.  As part of this framework a
   new SIP event package is defined here for the notification of profile
   changes.  This framework is also intended to ease ongoing
   administration and upgrading of large scale deployments of SIP user
   agents.  The contents and format of the profile data to be defined is
   outside the scope of this document.





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Table of Contents

   1.   Motivation . . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.   Introduction . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.1  Requirements Terminology . . . . . . . . . . . . . . . . . .   3
   2.2  Profile Delivery Framework Terminology . . . . . . . . . . .   4
   2.3  Overview . . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.   Profile Change Event Notification Package  . . . . . . . . .   5
   3.1  Event Package Name . . . . . . . . . . . . . . . . . . . . .   6
   3.2  Event Package Parameters . . . . . . . . . . . . . . . . . .   6
   3.3  SUBSCRIBE Bodies . . . . . . . . . . . . . . . . . . . . . .   7
   3.4  Subscription Duration  . . . . . . . . . . . . . . . . . . .   7
   3.5  NOTIFY Bodies  . . . . . . . . . . . . . . . . . . . . . . .   8
   3.6  Notifier processing of SUBSCRIBE requests  . . . . . . . . .   8
   3.7  Notifier generation of NOTIFY requests . . . . . . . . . . .   9
   3.8  Subscriber processing of NOTIFY requests . . . . . . . . . .  10
   3.9  Handling of forked requests  . . . . . . . . . . . . . . . .  10
   3.10 Rate of notifications  . . . . . . . . . . . . . . . . . . .  10
   3.11 State Agents . . . . . . . . . . . . . . . . . . . . . . . .  10
   3.12 Examples . . . . . . . . . . . . . . . . . . . . . . . . . .  10
   3.13 Use of URIs to Retrieve State  . . . . . . . . . . . . . . .  11
   4.   Profile Delivery Framework Details . . . . . . . . . . . . .  12
   4.1  Discovery of Subscription URI  . . . . . . . . . . . . . . .  12
   4.2  Enrollment with Profile Server . . . . . . . . . . . . . . .  13
   4.3  Notification of Profile Changes  . . . . . . . . . . . . . .  13
   4.4  Retrieval of Profile Data  . . . . . . . . . . . . . . . . .  14
   4.5  Upload of Profile Changes  . . . . . . . . . . . . . . . . .  14
   5.   IANA Considerations  . . . . . . . . . . . . . . . . . . . .  14
   6.   Security Considerations  . . . . . . . . . . . . . . . . . .  14
   6.1  Symmetric Encryption of Profile Data . . . . . . . . . . . .  14
   6.2  Client Certificate Authentication with HTTPS . . . . . . . .  15
   6.3  HTTPS Authentication . . . . . . . . . . . . . . . . . . . .  15
   7.   Differences from Simple XCAP Package . . . . . . . . . . . .  15
   8.   Open Issues  . . . . . . . . . . . . . . . . . . . . . . . .  16
   9.   Change History . . . . . . . . . . . . . . . . . . . . . . .  16
   9.1  Changes from draft-ietf-sipping-config-framework-00.txt  . .  16
   9.2  Changes from draft-petrie-sipping-config-framework-00.txt  .  17
   9.3  Changes from draft-petrie-sip-config-framework-01.txt  . . .  17
   9.4  Changes from draft-petrie-sip-config-framework-00.txt  . . .  17
        References . . . . . . . . . . . . . . . . . . . . . . . . .  18
        Author's Address . . . . . . . . . . . . . . . . . . . . . .  20
   A.   Acknowledgments  . . . . . . . . . . . . . . . . . . . . . .  20
        Intellectual Property and Copyright Statements . . . . . . .  21








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1. Motivation

   Today all SIP user agent vendors use proprietary means of delivering
   user or device profiles to the user agent.  The profile delivery
   framework defined in this document is intended to enable a first
   phase migration to a standard means of providing profiles to SIP user
   agents.  It is expected that UA vendors will be able to use this
   framework as a means of delivering their existing proprietary user
   and device data profiles (i.e. using their existing proprietary
   binary or text formats).  This in itself is a tremendous advantage in
   that a SIP environment can use a single profile delivery server for
   profile data to user agents from multiple vendors.  Follow-on
   standardization activities can:
   1.  define a standard profile content format framework (e.g. XML with
       name spaces [??] or name-value pairs [RFC0822]).
   2.  specify the content (i.e. name the profile data parameters, xml
       schema, name spaces) of the data profiles.

   One of the objectives of the framework described in this document is
   to provide a start up experience similar to that of users of an
   analog telephone.  When you plug in an analog telephone it just works
   (assuming the line is live and the switch has been provisioned).
   There is no end user configuration required to make analog phone work
   (at least in a basic sense).  So the objective here is to be able to
   take a new SIP user agent out of the box, plug it in (or install the
   software) and have it get its profiles without human intervention
   (other than security measures).  This is necessary for cost effective
   deployment of large numbers of user agents.

   Another objective is to provide a scalable means for on going
   administration of profiles.  Administrators and users are likely to
   want to make changes to user and device profiles.

   Additional requirements for the framework defined in this document
   are described in: [I-D.ietf-sipping-ua-prof-framewk-reqs],
   [I-D.sinnreich-sipdev-req]

2. Introduction


2.1 Requirements Terminology

   Keywords "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT" and
   "MAY" that appear in this document are to be interpreted as described
   in RFC 2119[RFC2119].






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2.2 Profile Delivery Framework Terminology

   profile - data set specific to a user or device.
   device - SIP user agent, either software or hardware appliance.
   profile content server - The server that provides the content of the
      profiles using the protocol specified by the URL scheme.
   notifier - The SIP user agent server which processes SUBSCRIBE
      requests for events and sends NOTIFY requests with profile URL(s).
   profile delivery server - The logical collection of the SIP  notifier
      and the server which provides the contents of the profile URL(s).

2.3 Overview

   The profile life cycle can be described by five functional steps.
   These steps are not necessarily discrete.  However it is useful to
   describe these steps as logically distinct.   These steps are named
   as follows:

   Discovery -  discover a profile delivery server
   Enrollment - enroll with the profile delivery server
   Profile Retrieval - retrieve profile data
   Profile Change Notification - receive notification of profile changes
   Profile Change Upload - upload profile data changes back to the
      profile delivery server

   Discovery is the process by which a UA SHOULD find the address and
   port at which it SHOULD enroll with the profile delivery server.  As
   there is no single discovery mechanism which will work in all network
   environments, a number of discovery mechanisms are defined with a
   prescribed order in which the UA SHOULD try them until one succeeds.

   Enrollment is the process by which a UA SHOULD make itself known to
   the profile delivery server. In enrolling the UA MUST provide
   identity information, name requested profile type(s) and supported
   protocols for profile retrieval.  It SHOULD also subscribe to a
   mechanism for notification of profile changes.  As a result of
   enrollment, the UA receives a URL for each of the profiles that the
   profile delivery server is able to provide.  Each profile type (set)
   requires a separate enrollment or SUBSCRIBE session.

   Profile Retrieval is the process of retrieving the content for each
   of the profiles the UA requested.

   Profile Change Notification is the process by which the profile
   delivery server    notifies the UA that the content of one or more of
   the profiles has changed. Subsequently the UA SHOULD retrieve the
   profile from the specified URL upon receipt of the change
   notification.



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   Profile Upload is the process by which a UA or other entity (e.g.
   OSS, corporate directory or configuration management server) pushes a
   change to the profile data back up to the profile delivery server.

   This framework defines a new SIP event package [RFC3265] to solve
   enrollment and profile change notification steps.

   The question arises as to why SIP should be used for the profile
   delivery framework.  In this document SIP is used for only a small
   portion of the framework.  Other existing protocols are more
   appropriate for transport of the profile contents (upstream and
   downstream of the user agent) and are suggested in this document.
   The discovery step is simply a specified order and application of
   existing protocols.  SIP is only needed for the enrollment and change
   notification functionality of the profile delivery framework.  In
   many SIP environments (e.g. carrier/subscriber and multi-site
   enterprise) firewall, NAT and IP addressing issues make it difficult
   to get messages between the profile delivery server and the user
   agent requiring the profiles.

   With SIP the users and devices already are assigned globally routable
   addresses.  In addition the firewall and NAT problems are already
   presumably solved in the environments in which SIP user agents are to
   be used.  Therefore SIP is the best solution for allowing the user
   agent to enroll with the profile delivery server which may require
   traversal of multiple firewalls and NATs.  For the same reason the
   notification of profile changes is best solved by SIP.

   It is assumed that the content delivery server MUST be either in the
   public network or accessible through a DMZ.  The user agents
   requiring profiles may be behind firewalls and NATs and many
   protocols, such as HTTP, may be used for profile content retrieval
   without special consideration in the firewalls and NATs.

   A conscious separation of user and device profiles is made in this
   document.  This is useful to provide features such as hoteling as
   well as securing or restricting user agent functionality.  By
   maintaining this separation, a user may walk up to someone else's
   user agent and direct that user agent to get their profile data.  In
   doing so the user agent can replace the previous user's profile data
   while still keeping the devices profile data that may be necessary
   for core functionality and communication described in this document.

3. Profile Change Event Notification Package

   This section defines a new SIP event package [RFC3265].  The purpose
   of this event package is to send to subscribers notification of
   content changes to the profile(s) of interest and to provide the



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   location of the profile(s) via content indirection
   [I-D.ietf-sip-content-indirect-mech].

3.1 Event Package Name

   The name of this package is "sip-profile". This value appears in the
   Event header field present in SUBSCRIBE and NOTIFY requests for this
   package as defined in [RFC3265].

3.2 Event Package Parameters

   This package defines the following new parameters for the event
   header: profile-type, vendor, model, version, effective-by.  The
   effective-by parameter is for use in NOTIFY requests only.  The
   others are for use in the SUBSCRIBE request, but may be used in
   NOTIFY requests as well.

   The profile-type parameter is used to indicate the profile type the
   user agent wishes to obtain URLs for and be notified of change.  This
   parameter allows the URL semantics to be opaque to the subscribing
   user agent as all it needs to know is the token value for this
   parameter.  This document defines two type categories of profiles.
   The contents or format of the profiles is outside the scope of this
   document.  The two types of profiles define here are "user" and
   "device".  Specifying device type profile(s) indicates the desire for
   the URL(s) and change notification of all profiles that are specific
   to the device or user agent.  Specifying user type profile(s)
   indicates the desire for the URL(s) and change notification of all
   profile(s) that are specific to the user.  The user or device is
   identified in the URI of the SUBSCRIBE request.  The Accept header of
   the SUBSCRIBE request MUST include the MIME types for all profile
   content types that the subscribing user agent wishes to retrieve
   profiles or receive change notifications.

      The user or device token in the profile-type parameter may
      represent a class or set of profiles as opposed to a single
      profile.  As standards are defined for specific profile contents
      related to the user or device, it may be desirable to define
      additional tokens for the profile-type header.  This is to allow a
      user agent to subscribe to that specific profile as opposed to the
      entire class or set of user or device profiles.

   The rational for the separation of user and device type profiles is
   provided in section Section 2.3.  It should be noted that either type
   may indicate that zero or more URLs are provided in the NOTIFY
   request.  As discussed, a default user may be assigned to a device.
   In this scenario the profile delivery server may provide the URL(s)
   in the NOTIFY request for the default user when subscribing to the



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   device profile type.  Effectively the  device profile type becomes a
   superset of the user profile type subscription.  The user type is
   still useful in this scenario to allow the user agent to obtain
   profile URLs for a user other than the default user.  This provides
   the ability to support a hoteling function where a user may "login"
   to any user agent and have it use a users profile(s).

   The vendor, model and version parameters are tokens specified by the
   vendor of the user agent.  These parameters are useful to the profile
   delivery server to effect the profiles provided.  In some scenarios
   it is desirable to provide different profiles based upon these
   parameters.  For example feature parameter X in a profile may work
   differently on two versions of user agent.  This gives the profile
   deliver server the ability to compensate for or take advantage of the
   differences.

   The "effective-by" parameter in the Event header of the NOTIFY
   specifies the maximum number of seconds before the user agent MUST
   make the new profile effective.  A value of 0 (zero) indicates that
   the user agent MUST make the profiles effective immediately (despite
   possible service interruptions).  This gives the profile delivery
   server the power to control when the profile is effective.  This may
   be important to resolve an emergency problem or disable a user agent
   immediately.

   SUBSCRIBE request example:
   Event: sip-profile;profile-type=device;
               vendor=acme;model=Z100;version=1.2.3

   NOTIFY request examples:
   Event:sip-profile;effective-by=0

   Event:sip-profile;effective-by=3600



3.3 SUBSCRIBE Bodies

   This package defines no new use of the SUBSCRIBE request body.

3.4 Subscription Duration

   As profiles are generally static with infrequent changes, it is
   recommended that default subscription duration be 86400 seconds (one
   day).






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3.5 NOTIFY Bodies

   The size of profile content is likely to be hundreds to several
   thousand bytes in size.  Frequently even with very modest sized SDP
   bodies, SIP messages get fragmented causing problems for many user
   agents.  For this reason the NOTIFY body MUST use content indirection
   [I-D.ietf-sip-content-indirect-mech] for providing the profiles.

   The profile delivery server MUST include the Content-ID defined in
   [I-D.ietf-sip-content-indirect-mech] for each profile URL.  This is
   to avoid unnecessary download of the profiles.  Some user agents are
   not able to make a profile effective without rebooting or restarting.
   Rebooting is probably something to be avoided on a user agent
   performing services such as telephony.  In this way the Content-ID
   allows the user agent to avoid unnecessary interruption of service as
   well.  The Content-Type MUST be specified for each URL.

      Initially it is expected that most user agent vendors will use a
      proprietary content type for the profiles retrieved from the
      URLs(s).   It is hoped that over time a standard content type will
      be specified that will be adopted by vendors of user agents.  One
      direction that appears to be promising for this content is to use
      XML with name spaces [??] to segment the data into sets that the
      user agent implementer may choose to support based upon desired
      feature set.  The specification of the content is out of the scope
      of this document.

   Likewise the URL scheme used in the content indirection is outside
   the scope of this document.  This document is agnostic to the URL
   schemes as the profile content may dictate what is required.  It is
   expected that  TFTP [RFC3617], FTP [??], HTTP [RFC2616], HTTPS
   [RFC2818], LDAP [RFC3377], XCAP [I-D.rosenberg-simple-xcap] and other
   URL schemes are supported by this package and framework.

3.6 Notifier processing of SUBSCRIBE requests

   The general rules for processing SUBSCRIBE requests [RFC3265] apply
   to this package.  The notifier does not need to authenticate the
   subscription as the profile content is not transported in the
   SUBSCRIBE or NOTIFY transaction messages.  Only URLs are transported
   in the NOTIFY request which may be secured using the techniques in
   section Section 6.

   The behavior of the profile delivery server is left to the
   implementer.  The profile delivery server may be as simple as a SIP
   SUBSCRIBE UAS and NOTIFY UAC front end to a simple HTTP server
   delivering static files that are hand edited.  At the other extreme
   the profile delivery server can be part of a configuration management



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   system that integrates with a corporate directory and IT system or
   carrier OSS, where the profiles are automatically generated.  The
   design of this framework intentionally provides the flexibility of
   implementation from simple/cheap to complex/expensive.

   If the user or device is not known to the profile delivery server,
   the implementer MAY accept the subscription or reject it.  It is
   recommended that the implementer accept the subscription.  It is
   useful for the profile delivery server to maintain the subscription
   as an administrator may add the user or device to the system,
   defining the profile contents.  This allow the profile delivery
   server to immediately send a NOTIFY request with the profile URLs.
   If the profile delivery server does not accept the subscription from
   an unknown user or device, the administer or user must manually
   provoke the user agent to reSUBSCRIBE.  This may be difficult if the
   user agent and administrator are at different sites.

3.7 Notifier generation of NOTIFY requests

   As in [RFC3265], the profile delivery server MUST always send a
   NOTIFY request upon accepting a subscription.  If the device or user
   is unknown to the profile delivery server and it chooses to accept
   the subscription, the implementer has two choices.  A NOTIFY MAY be
   sent with no body or content indirection containing the profile
   URL(s).  Alternatively a NOTIFY MAY be sent with URL(s) pointing to a
   default data set.  Typically this data set allows for only limited
   functionality of the user agent (e.g. a phone user agent with data to
   call help desk and emergency services.).  This is an implementation
   and business policy decision.

   A user or device known and fully provisioned on the profile delivery
   server SHOULD send a NOTIFY with content indirection containing URLs
   for all of the profiles associated with the user or device (i.e.
   which ever specified in the profile-type parameter).  The device may
   be associated with a default user.  The URL(s) for this default user
   profiles MAY be included with the URL(s) of the device if the profile
   type specified is device.

   A user agent can provide Hoteling by collecting a user’s AOR and
   credentials needed to SUBSCRIBE and retrieve the user profiles from
   the URL(s).  Hoteling functionality is achieved by subscribing to the
   AOR and specifying the "user" profile type.  This same mechanism can
   be used to secure a user agent, requiring a user to login to enable
   functionality beyond the default user’s restricted functionality.

   The profile delivery server MAY specify when the new profiles MUST be
   made effective by the user agent.  By default the user agent makes
   the profiles effective as soon as it thinks that it is non-obtrusive.



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   However the profile delivery server MAY specify a maximum time in
   seconds (zero or more), in the effective-by event header parameter,
   by which the user agent MUST make the new profiles effective.

3.8 Subscriber processing of NOTIFY requests

   The user agent subscribing to this event package MUST adhere to the
   NOTIFY request processing behavior specified in [RFC3265].  The user
   agent MUST make the profiles effective as specified in the NOTIFY
   request (see section Section 3.7).  The user agent SHOULD use one of
   the techniques specified in section [RFC3265] to securely retrieve
   the profiles.

3.9 Handling of forked requests

   This event package allows the creation of only one dialog as a result
   of an initial SUBSCRIBE request.  The techniques to achieve this are
   described in section 4.4.9 of [RFC3265].

3.10 Rate of notifications

   It is anticipated that the rate of change for user and device
   profiles will be very infrequent (i.e. days or weeks apart).  For
   this reason no throttling or minimum period between NOTIFY requests
   is specified for this package.

3.11 State Agents

   State agents are not applicable to this event package.

3.12 Examples


   SUBSCRIBE sip:00df1e004cd0@example.com SIP/2.0
   Event: sip-profile;profile-type=device;vendor=acme;
                            model=Z100;version=1.2.3
   From: sip:00df1e004cd0@acme.com;tag=1234
   To: sip:00df1e004cd0@acme.com;tag=abcd
   Call-ID: 3573853342923422@10.1.1.44
   CSeq: 2131 SUBSCRIBE
   Contact: sip:00df1e004cd0@10.1.1.44
   Content-Length: 0



   NOTIFY sip:00df1e004cd0@10.1.1.44 SIP/2.0
   Event: sip-profile;effective-by=3600
   From: sip:00df1e004cd0@acme.com;tag=abcd



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   To: sip:00df1e004cd0@acme.com;tag=1234
   Call-ID: 3573853342923422@10.1.1.44
   CSeq: 321 NOTIFY
   MIME-Version: 1.0
   Content-Type: multipart/mixed; boundary=boundary42
   Content-Length: ...

   --boundary42
   Content-Type: message/external-body;
       access-type="URL";
       expiration="Mon, 24 June 2002 09:00:00 GMT";
           URL="http://www.example.com/devices/fsmith";
           size=2222

   Content-Type: application/z100-user-profile
   Content-ID: <69ADF2E92@example.com>

   --boundary42
   Content-Type: message/external-body;
       access-type="URL";
       expiration="Mon, 24 June 2002 09:00:00 GMT";
           URL="http://www.example.com/devices/ff00000036c5";
           size=1234

   Content-Type: application/z100-device-profile
   Content-ID: <39EHF78SA@example.com>

   --boundary42--


3.13 Use of URIs to Retrieve State

   The profile type specified determines what goes in the user part of
   the SUBSRIBE URI.  If the profile type requested is "device", the
   user part is an identity that MUST be unique across all user agents
   from all vendors.  This identity must be static over time so that the
   profile delivery server can keep it associated with its profiles.
   For Ethernet hardware type user agents supporting only a single user
   at a time this is most easily accomplished using its MAC address.
   Software based user agents running on general purpose hardware may
   also be able to use the MAC address for identity.  However in
   situations where multiple instance of user agents are running on the
   same hardware it may be necessary to use a another scheme, such as
   using a unique serial number for the software.

   If the profile type request is "user" the URI in the SUBSCRIBE
   request is the address of record for the user.   This allows the user
   to specify (e.g. login) to the user agent by simply entering their



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   known identity.

4. Profile Delivery Framework Details

   The following describes how different functional steps of the profile
   delivery framework work.  Also described here is how the event
   package defined in this document provides the enrollment and
   notification functions within the framework.

4.1 Discovery of Subscription URI

   The discovery function is needed to bootstrap user agents to the
   point of knowing where to enroll with the profile delivery server.
   Section Section 3.13 describes how to form the URI used to sent the
   SUBSCRIBE request for enrollment.  However the bootstrapping problem
   for the user agent (out of the box) is what to use for the host and
   port in the URI.  Due to the wide variation of environments in which
   the enrolling user agent may reside (e.g. behind residential router,
   enterprise LAN, ISP, dialup modem) and the limited control that the
   administrator of the profile delivery server (e.g. enterprise,
   service provider) may have over that environment, no single discovery
   mechanism works everywhere.  Therefore a number of mechanisms SHOULD
   be tried in the specified order: SIP DHCP option [RFC3361], SIP DNS
   SRV [RFC3263], DNS A record and manual.

   1.  The first discovery mechanizm that SHOULD be tried is to
       construct the SUBSCRIBE URI as described in Section 3.13 using
       the host and port of out bound proxy discovered by the SIP DHCP
       option as described in [RFC3361].  If the SIP DHCP option is not
       provided in the DHCP response, no SIP response or a SIP failure
       response other than for authorization is received for the
       SUBSCRIBE request to the sip-profile event, the next discovery
       mechanism SHOULD be tried.
   2.  The local IP network domain for the user agent, either configured
       or discovered via DHCP, should be used with the technique in
       [RFC3263] to obtain a host and port to use in the SUBSCRIBE URI.
       If no SIP response or a SIP failure response other than for
       authorization is received for the SUBSCRIBE request to the
       sip-profile event, the next discovery mechanism SHOULD be tried.
   3.  The fully qualified host name constructed using the host name
       "sipuaconfig" and concatenated with the local IP network domain
       should be tried next using the technique in [RFC3263] to obtain a
       host and port to use in the SUBSCRIBE URI.  If no SIP response or
       a SIP failure response other than for authorization is received
       for the SUBSCRIBE request to the sip-profile event, the next
       discovery mechanism SHOULD be tried.
   4.  If all other discovery techniques fail, the user agent MUST
       provide a manual means for the user to enter the host and port



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       used to construct the SUBSCRIBE URI.

   Once a user agent has successfully discovered, enrolled, received a
   NOTIFY response with profile URL(s), the user agent SHOULD cache the
   SUBCRIBE URI to avoid having to rediscover the profile delivery
   server again in the future.  The user agent SHOULD NOT cache the
   SUBSCRIBE URI until it receives a NOTIFY with profile URL(s).  The
   reason for this is that a profile delivery server may send 202
   responses to SUBSCRIBE requests and NOTIFY responses to unknown user
   agent (see section Section 3.6) with no URLs.  Until the profile
   delivery server has sent a NOTIFY request with profile URL(s), it has
   not agreed to provide profiles.

      To illustrate why the user agent should not cache the SUBSCRIBE
      URI until profile URL(s) are provided in the NOTIFY, consider the
      following example:  a user agent running on a laptop plugged into
      a visited LAN in which a foreign profile delivery server is
      discovered.  The profile delivery server never provides profile
      URLs in the NOTIFY request as it is not provisioned to accept the
      user agent.  The user then takes the laptop to their enterprise
      LAN.  If the user agent cached the SUBSCRIBE URI from the visited
      LAN (which did not provide profiles), the user agent would not
      attempt to discover the profile delivery server in the enterprise
      LAN which is provisioned to provide profiles to the user agent..

4.2 Enrollment with Profile Server

   Enrollment is accomplished by subscribing to the event package
   described in section Section 3.  The enrollment process is useful to
   the profile delivery server as it makes the server aware of user
   agent to which it may delivery profiles (those user agents the
   profile delivery server is provisioned to provide profiles to; those
   present that the server may be provide profiles in the future; and
   those that the server can automatically provide default profiles).
   It is an implementation choice and business policy as to whether the
   profile delivery server provides profiles to user agents that it is
   not provisioned to do so.  However the profile server SHOULD accept
   (with 2xx response) SUBSCRIBE requests from any user agent.

4.3 Notification of Profile Changes

   The NOTIFY request in the sip-profile event package server two
   purposes.  First it provides the user agent with a means to obtain
   the URL(s) for desired profiles without requiring the end user to
   manually enter them.  It also provides the means for the profile
   delivery server to notify the user agent that the content of the
   profiles have changed and should be made effective.




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4.4 Retrieval of Profile Data

   The user agent retrieves it's needed profile(s) via the URL(s)
   provide in the NOTIFY request as specified in section Section 3.5.
   The profile delivery server SHOULD secure the content of the profiles
   using one of the techniques described in Section 6.  The user agent
   SHOULD make the new profiles effective in the timeframe described in
   section Section 3.2.

   The contents of the profiles SHOULD be cached by the user agent.
   This it to avoid the situation where the content delivery server is
   not available, leaving the user agent non-functional.

4.5 Upload of Profile Changes

   The user agent or other service MAY push changes up to the profile
   delivery server using the technique appropriate to the profile's URL
   scheme (e.g. HTTP PUT method, FTP put command).  The technique for
   pushing incremental or atomic changes MUST be described by the
   specific profile data framework.

5. IANA Considerations

   [TBD]

6. Security Considerations

   Profiles may contain sensitive data such as user credentials.  The
   protection of this data is accomplished via the profile retrieval
   function.  This simplifies the security solution as the SIP event
   package does not need to authenticate, authorize or protect the
   contents of the SIP messages.  Effectively the profile delivery
   server will provide profile URL(s) to any one.  The URLs themselves
   are protected via authentication, authorization and snooping.  Three
   options for secure retrieval of profiles are follow:

6.1 Symmetric Encryption of Profile Data

   One security technique is to encrypted the profiles on the content
   delivery server using the AES symmetric encryption algorithm using a
   key formed by a MD5 hash of the following: username ":" password.
   The encrypted profiles are delivered by the content delivery server
   via the URLs provided in the NOTIFY requests.  Using this technique
   the profile delivery server does not need to provide authentication
   or authorization for the retrieval as the profiles are obscured.  The
   user agent must obtain the username and password from the user to
   generate the key and perform AES decryption the profiles.  This is
   the simplest security technique as it does not require any public key



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   infrastructure or TLS implementation on the user agent (which often
   has limited resources).

6.2 Client Certificate Authentication with HTTPS

   In another technique the content delivery server authenticates the
   user or user agent by requesting the client's certificate in the TLS
   connection established as described by the profile URL.  The content
   delivery server authorizes the profile retrieval using the
   certificate identity and business policy choices provide by the
   server implementer. The profile data is obscured from snooping using
   the encryption mechanisms provide by the TLS connect.  This has nice
   properties of not requiring end user intervention, but has a higher
   administrative cost for user agent certificate management and
   distribution.  It also requires the certificates to be in place
   before enabling profile delivery.

6.3 HTTPS Authentication

   Alternatively the authentication mechanizms described in [RFC2617]
   are used.  The content delivery server authorizes the profile
   retrieval using the certificate identity and business policy choices
   provide by the server implementer. The profile data is obscure from
   snooping using the encryption mechanisms provide by the TLS connect.
   This also requires the overhead of a TLS implementation on the user
   agent.

   For all of these techniques the user agent should take care in how it
   stores or caches the profiles to avoid theft.  It is recommended that
   a symmetric encryption technique such as that described in section
   Section 6.1 be used.  This also requires the overhead of a TLS
   implementation on the user agent.

7. Differences from Simple XCAP Package

   The author of this document had an action item from the July 2003
   IETF SIPPING WG meeting to consider resolving the differences of the
   sip-profile and simple XCAP package [I-D.ietf-simple-xcap-package].
   It is the author's opinion that XCAP [I-D.rosenberg-simple-xcap] can
   be supported by the framework and event package defined in this
   document as it is simply a URL using the HTTP or HTTPS scheme.  The
   following lists the differences between the event packaged defined in
   this document vs. the one defined in [I-D.ietf-simple-xcap-package].

   The simple XCAP package requires that the relative path be known and
   specified by the user agent when subscribing for change notification.
   The event package in this document requires a token be known and
   specified when subscribing.  The advantage of the latter is that



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   bootstrapping is easier and well defined.  It also leaves the freedom
   of specifying the entire path of the profile URL up to the profile
   delivery server.

   The event package defined in this document allows multiple URLs to be
   provided in the NOTIFY request body as a result of a single token
   specified in the SUBSCRIBE event parameter: profile-type.  This
   allows the profile delivery server to provide sets of profiles that
   the user agent may not have enough information to specify in the
   SUBSCRIBE URI (e.g. at boot strapping time the user agent may not
   know the user's identity, but the profile delivery server may know
   the default user for the device's identity) or the doc-component of
   the simple XCAP package.

   The simple XCAP package provides profile data changes or deltas in
   the body of the NOTIFY request.  This is a desirable feature, but
   approach in the simple XCAP package has a few disadvantages:

   o  SIP signaling requires authentication, authorization and
      encryption (SIPS) to protect the profiles where the event package
      in this document does not.  SIPS may require more resources than
      are available on many user agents.
   o  The content of a profile change may be large, causing
      fragmentation and problems or constraints when using UDP.

   The feature of providing profile data changes or deltas can be
   provided in the package proposed in this document by providing two
   URLs in the NOTIFY request for each profile (i.e. a URL for the
   complete profile and another for the changes).

   All other functional differences between
   draft-ietf-sipping-config-framework-00 and
   draft-ietf-simple-xcap-package-00 are believed to be resolved in this
   version of this document.

8. Open Issues


9. Change History


9.1 Changes from draft-ietf-sipping-config-framework-00.txt

   This version of the document was entirely restructured and re-written
   from the previous version as it had been micro edited too much.

   All of the aspects of defining the event package are now organized in
   one section and is believed to be complete and up to date with



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   [RFC3265].

   The URI used to subscribe to the event package is now either the user
   or device address or record.

   The user agent information (vendor, model, MAC and serial number) are
   now provided as event header parameters.

   Added a mechanism to force profile changes to be make effective by
   the user agent in a specified maximum period of time.

   Changed the name of the event package from sip-config to sip-profile

   Three high level securityapproaches are now specified.

9.2 Changes from draft-petrie-sipping-config-framework-00.txt

   Changed name to reflect SIPPING work group item

   Synchronized with changes to SIP DHCP [RFC3361], SIP [RFC3261] and
   [RFC3263], SIP Events [RFC3265] and content indirection
   [I-D.ietf-sip-content-indirect-mech]

   Moved the device identity parameters from the From field parameters
   to User-Agent header parameters.

   Many thanks to Rich Schaaf of Pingtel, Cullen Jennings of Cisco and
   Adam Roach of Dyamicsoft for the great comments and input.

9.3 Changes from draft-petrie-sip-config-framework-01.txt

   Changed the name as this belongs in the SIPPING work group.

   Minor edits

9.4 Changes from draft-petrie-sip-config-framework-00.txt

   Many thanks to those who contributed and commented on the previous
   draft.  Detailed comments were provided by Henning Schulzrinne from
   Columbia U., Cullen Jennings from Cisco, Rohan Mahy from Cisco, Rich
   Schaaf from Pingtel.

   Split the enrollment into a single SUBSCRIBE dialog for each profile.
   The 00 draft sent a single SUBSCRIBE listing all of the desired.
   These have been split so that each enrollment can be routed
   differently.  As there is a concept of device specific and

   user specific profiles, these may also be managed on separate



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   servers.  For instance in a roaming situation the device might get
   it's profile data from a local server which knows the LAN specific
   profile data.  At the same time the user specific profiles might come
   from the user's home environment profile delivery server.

   Removed the Config-Expires header as it is largely superfluous with
   the SUBSCRIBE Expires header.

   Eliminated some of the complexity in the discovery mechanism.

   Suggest caching information discovered about a profile delivery
   server to avoid an avalanche problem when a whole building full of
   devices powers up.

   Added the User-Profile From header field parameter so that the device
   can a request a user specific profile for a user that is different
   from the device's default user.

References

   [I-D.ietf-simple-xcap-package]
              Rosenberg, J., "A Session Initiation Protocol (SIP) Event
              Package for Modification  Events for the Extensible Markup
              Language (XML) Configuration Access Protocol (XCAP)
              Managed Documents", draft-ietf-simple-xcap-package-00
              (work in progress), June 2003.

   [I-D.ietf-sip-content-indirect-mech]
              Olson, S., "A Mechanism for Content Indirection in Session
              Initiation Protocol (SIP)  Messages",
              draft-ietf-sip-content-indirect-mech-03 (work in
              progress), June 2003.

   [I-D.ietf-sipping-ua-prof-framewk-reqs]
              Petrie, D. and C. Jennings, "Requirements for SIP User
              Agent Profile Delivery Framework",
              draft-ietf-sipping-ua-prof-framewk-reqs-00 (work in
              progress), March 2003.

   [I-D.rosenberg-simple-xcap]
              Rosenberg, J., "The Extensible Markup Language (XML)
              Configuration Access Protocol  (XCAP)",
              draft-rosenberg-simple-xcap-00 (work in progress), May
              2003.

   [I-D.sinnreich-sipdev-req]
              Butcher, I., Lass, S., Petrie, D., Sinnreich, H. and C.
              Stredicke, "SIP Telephony Device Requirements,



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              Configuration and Data", draft-sinnreich-sipdev-req-02
              (work in progress), October 2003.

   [RFC0822]  Crocker, D., "Standard for the format of ARPA Internet
              text messages", STD 11, RFC 822, August 1982.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2131]  Droms, R., "Dynamic Host Configuration Protocol", RFC
              2131, March 1997.

   [RFC2132]  Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor
              Extensions", RFC 2132, March 1997.

   [RFC2246]  Dierks, T., Allen, C., Treese, W., Karlton, P., Freier, A.
              and P. Kocher, "The TLS Protocol Version 1.0", RFC 2246,
              January 1999.

   [RFC2616]  Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
              Masinter, L., Leach, P. and T. Berners-Lee, "Hypertext
              Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.

   [RFC2617]  Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S.,
              Leach, P., Luotonen, A. and L. Stewart, "HTTP
              Authentication: Basic and Digest Access Authentication",
              RFC 2617, June 1999.

   [RFC2818]  Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000.

   [RFC3261]  Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
              A., Peterson, J., Sparks, R., Handley, M. and E. Schooler,
              "SIP: Session Initiation Protocol", RFC 3261, June 2002.

   [RFC3263]  Rosenberg, J. and H. Schulzrinne, "Session Initiation
              Protocol (SIP): Locating SIP Servers", RFC 3263, June
              2002.

   [RFC3265]  Roach, A., "Session Initiation Protocol (SIP)-Specific
              Event Notification", RFC 3265, June 2002.

   [RFC3361]  Schulzrinne, H., "Dynamic Host Configuration Protocol
              (DHCP-for-IPv4) Option for Session Initiation Protocol
              (SIP) Servers", RFC 3361, August 2002.

   [RFC3377]  Hodges, J. and R. Morgan, "Lightweight Directory Access
              Protocol (v3): Technical Specification", RFC 3377,
              September 2002.



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   [RFC3617]  Lear, E., "Uniform Resource Identifier (URI) Scheme and
              Applicability Statement for the Trivial File Transfer
              Protocol (TFTP)", RFC 3617, October 2003.


Author's Address

   Daniel Petrie
   Pingtel Corp.
   400 W. Cummings Park
   Suite 2200
   Woburn, MA  01801
   US

   Phone: "Dan Petrie (+1 781 970 0111)"<sip:dpetrie@pingtel.com>
   EMail: dpetrie@pingtel.com
   URI:   http://www.pingtel.com/

Appendix A. Acknowledgments
































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   This document and the information contained herein is provided on an
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