SIPPING                                                        D. Petrie
Internet-Draft                                                SIPez LLC.
Intended status: Standards Track                   S. Channabasappa, Ed.
Expires: August 16, 2008 April 1, 2010                                         CableLabs
                                                       February 13, 2008
                                                      September 28, 2009

A Framework for Session Initiation Protocol User Agent Profile Delivery

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   This document specifies a framework to enable configuration of
   Session Initiation Protocol (SIP) User Agents in SIP deployments.
   The framework provides a means to deliver profile data that User
   Agents need to be functional, automatically and with minimal or no
   User and Administrative intervention.  The framework describes how
   SIP User Agents can discover sources, request profiles and receive
   notifications related to profile modifications.  As part of this
   framework, a new SIP event package is defined for notification of
   profile changes.  The framework provides minimal data retrieval
   options to ensure interoperability.  The framework does not include
   specification of the profile data within its scope.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4  5
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  4  5
   3.  Overview . . . . . . . . . . . . . . . . . . . . . . . . . . .  5  6
     3.1.  Reference Model  . . . . . . . . . . . . . . . . . . . . .  6  7
     3.2.  Motivation . . . . . . . . . . . . . . . . . . . . . . . .  7  8
     3.3.  Profile Types  . . . . . . . . . . . . . . . . . . . . . .  9 10
     3.4.  Profile delivery stages  . . . . . . . . . . . . . . . . . 10 11
   4.  Use Cases  . . . . . . . . . . . . . . . . . . . . . . . . . . 10 11
     4.1.  Simple Deployment Scenario . . . . . . . . . . . . . . . . 11 12
     4.2.  Devices supporting multiple users from different
           Service Providers  . . . . . . . . . . . . . . . . . . . . 12 13
   5.  Profile Delivery Framework . . . . . . . . . . . . . . . . . . 14 15
     5.1.  Profile delivery stages  . . . . . . . . . . . . . . . . . 14 15
       5.1.1.  Profile Enrollment . . . . . . . . . . . . . . . . . . 15 16
       5.1.2.  Content Retrieval  . . . . . . . . . . . . . . . . . . 17 18
       5.1.3.  Change Notification  . . . . . . . . . . . . . . . . . 17 18
       5.1.4.  Enrollment Data and Caching  . . . . . . . . . . . . . 18 19
     5.2.  Securing Profile Delivery  . . . . . . . . . . . . . . . . 21 22
       5.2.1.  Securing Profile Enrollment  . . . . . . . . . . . . . 22 23
       5.2.2.  Securing Content Retrieval . . . . . . . . . . . . . . 23 24
       5.2.3.  Securing Change Notification . . . . . . . . . . . . . 24 25
     5.3.  Additional Considerations  . . . . . . . . . . . . . . . . 24 25
       5.3.1.  Bootstrapping Identities and Credentials . . . . . . . 24 25
       5.3.2.  Profile Enrollment Request Attempt . . . . . . . . . . 26 27
       5.3.3.  Device Types . . . . . . . . . . . . . . . . . . . . . 30 31
       5.3.4.  Profile Data . . . . . . . . . . . . . . . . . . . . . 30 31
       5.3.5.  Profile Data Frameworks  . . . . . . . . . . . . . . . 31 32
       5.3.6.  Additional Profile Types . . . . . . . . . . . . . . . 32 33
       5.3.7.  Deployment considerations  . . . . . . . . . . . . . . 32 33
     5.4.  Support for NATs . . . . . . . . . . . . . . . . . . . . . 33 34
   6.  Event Package Definition . . . . . . . . . . . . . . . . . . . 33 34
     6.1.  Event Package Name . . . . . . . . . . . . . . . . . . . . 33 34
     6.2.  Event Package Parameters . . . . . . . . . . . . . . . . . 33 34
     6.3.  SUBSCRIBE Bodies . . . . . . . . . . . . . . . . . . . . . 36 37
     6.4.  Subscription Duration  . . . . . . . . . . . . . . . . . . 37 38
     6.5.  NOTIFY Bodies  . . . . . . . . . . . . . . . . . . . . . . 37 38
     6.6.  Notifier Processing of SUBSCRIBE Requests  . . . . . . . . 37 38
     6.7.  Notifier Generation of NOTIFY Requests . . . . . . . . . . 38 39
     6.8.  Subscriber Processing of NOTIFY Requests . . . . . . . . . 38 39
     6.9.  Handling of Forked Requests  . . . . . . . . . . . . . . . 39 40
     6.10. Rate of Notifications  . . . . . . . . . . . . . . . . . . 39 40
     6.11. State Agents . . . . . . . . . . . . . . . . . . . . . . . 39 40
   7.  Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 40
     7.1.  Example 1: Device requesting profile . . . . . . . . . . . 39 40
     7.2.  Example 2: Device obtaining change notification  . . . . . 42 43
   8.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 46 47
     8.1.  SIP Event Package  . . . . . . . . . . . . . . . . . . . . 46 47
     8.2.  Registry of SIP configuration profile types  . . . . . . . 46 47
   9.  Security Considerations  . . . . . . . . . . . . . . . . . . . 47 48
     9.1.  Local-network profile  . . . . . . . . . . . . . . . . . . 48 49
     9.2.  Device profile . . . . . . . . . . . . . . . . . . . . . . 49 50
     9.3.  User profile . . . . . . . . . . . . . . . . . . . . . . . 51 52
   10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 51 52
   11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 52 53
     11.1. Normative References . . . . . . . . . . . . . . . . . . . 52 53
     11.2. Informative References . . . . . . . . . . . . . . . . . . 53 54
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 54
   Intellectual Property and Copyright Statements . . . . . . . . . . 55

1.  Introduction

   SIP User Agents require configuration data to function properly.
   Examples include local network, device and user specific information.
   A configuration data set specific to an entity is termed a profile.
   For example, device profile contains the configuration data related
   to a device.  The process of providing devices with one or more
   profiles is termed profile delivery.  Ideally, this profile delivery
   process should be automatic and require minimal or no user

   Many deployments of SIP User Agents require dynamic configuration and
   cannot rely on pre-configuration.  This framework provides a standard
   means of providing dynamic configuration which simplifies deployments
   containing SIP User Agents from multiple vendors.  This framework
   also addresses change notifications when profiles change.  However,
   the framework does not define the content or format of the profile,
   leaving that to future standardization activities.

   This document is organized as follows.  Section 3 provides a high-
   level overview of the abstract components, profiles, and the profile
   delivery stages.  Section 4 provides some motivating use cases.
   Section 5 provides details of the framework operation and
   requirements.  Section 6 provides a concise event package definition.
   Section 7 follows with illustrative examples of the framework in use.

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in RFC 2119 [RFC2119].

   This document also reuses the SIP terminology defined in [RFC3261]
   and [RFC3265], and specifies the usage of the following terms.

   Device:  software or hardware entity containing one or more SIP user
      agents.  It may also contain entities such as a DHCP client.

   Device Provider:  the entity responsible for managing a given device.

   Local Network Provider:  the entity that controls the local network
      to which a given device is connected.

   SIP Service Provider:  the entity providing SIP services to users.
      This can refer to private enterprises or public entities.

   Profile:  configuration data set specific to an entity (e.g., user,
      device, local network or other).

   Profile Type:  a particular category of Profile data (e.g., User,
      Device, Local Network or other).

   Profile Delivery Server (PDS):  the source of a Profile, it is the
      logical collection of the Profile Notification Component (PNC) and
      the Profile Content Component(PCC).

   Profile Notification Component (PNC):  the logical component of a
      Profile Delivery Server that is responsible for enrolling devices
      and providing profile notifications.

   Profile Content Component (PCC):  the logical component of a Profile
      Delivery Server that is responsible for storing, providing access
      to, and accepting profile content.

   Profile Delivery Stages:  the processes that lead a device to obtain
      profile data, and any subsequent changes, are collectively called
      profile delivery stages.

3.  Overview

   This section provides an overview of the configuration framework.  It
   presents the reference model, the motivation, the profile delivery
   stages and a mapping of the concepts to specific use cases.  It is
   meant to serve as a reference section for the document, rather than
   providing a specific logical flow of material, and it may be
   necessary to revisit these sections for a complete appreciation of
   the framework.

   The SIP UA Profile Delivery Framework uses a combination of SIP event
   messages (SUBSCRIBE and NOTIFY; [RFC3265]) and traditional file
   retrieval protocols, such as HTTP [RFC2616], to discover, monitor,
   and retrieve configuration profiles.  The framework defines three
   types of profiles (local-network, device, and user) in order to
   separate aspects of the configuration which may be independently
   managed by different administrative domains.  The initial SUBSCRIBE
   message for each profile allows the UA to describe itself (both its
   implementation and the identity requesting the profile), while
   requesting access to a profile by type, without prior knowledge of
   the profile name or location.  Discovery mechanisms are specified to
   help the UA form the subscription URI (the Request URI for the SIP
   SUBSCRIBE).  The SIP UAS handling these subscriptions is the Profile
   Delivery Server (PDS).  When the PDS accepts a subscription, it sends
   a NOTIFY to the device.  The initial NOTIFY from the PDS for each
   profile may contain profile data or a reference to the location of
   the profile, to be retrieved using HTTP or similar file retrieval
   protocols.  By maintaining a subscription to each profile, the UA
   will receive additional NOTIFY messages if the profile is later
   changed.  These may contain a new profile, a reference to a new
   profile, or a description of profile changes, depending on the
   Content-Type [RFC3261] in use by the subscription.  The framework
   describes the mechanisms for obtaining three different profile types,
   but does not describe the data model they utilize (the data model is
   out of scope for this specification).

3.1.  Reference Model

   The design of the framework was the result of a careful analysis to
   identify the configuration needs of a wide range of SIP deployments.
   As such, the reference model provides for a great deal of
   flexibility, while breaking down the interactions to their basic
   forms, which can be reused in many different scenarios.

   The reference model for the framework defines the interactions
   between the Profile Delivery Server(PDS) and the device.  The device
   needs the profile data to function effectively in the network.  The
   PDS is responsible for responding to device requests and providing
   the profile data.  The reference model is illustrated in Figure 1.

    +--------+                            | Profile Delivery Server |
    | Device |<==========================>|  +---+          +---+   |
    +--------+                            |  |PNC|          |PCC|   |
                                          |  +---+          +---+   |

                                PNC = Profile Notification Component
                                PCC = Profile Content Component

                    Figure 1: Framework Reference Model

   The PDS is subdivided into two logical components:
   o  Profile Notification Component (PNC), responsible for enrolling
      devices for profiles and providing profile change notifications;
   o  Profile Content Component (PCC), responsible for storing,
      providing access to, and accepting modifications related to
      profile content.

3.2.  Motivation

   The motivation for the framework can be demonstrated by applying the
   reference model presented in Section 3.1 to two scenarios that are
   representative of the two ends of a spectrum of potential SIP

   In the simplest deployment scenario, a device connects through a
   network that is controlled by a single provider who provides the
   local-network, manages the devices, and offers services to the users.
   The provider propagates profile data to the device that contains all
   the necessary information to obtain services in the network
   (including information related to the local-network and the users).
   This is illustrated in Figure 2.  An example is a simple enterprise
   network that supports SIP-based devices.

          / Local-network, \
         | Device & Service |
          \    Provider    /
              | Device |

                     Figure 2: Simple Deployment Model

   In more complex deployments, devices connect via a local network that
   is not controlled by the SIP Service Provider, such as devices that
   connect via available public WiFi hot spots.  In such cases, local
   network providers may wish to provide local network information such
   as bandwidth constraints to the devices.

   Devices may also be controlled by device providers that are
   independent of the SIP service provider who provides user services,
   such as kiosks that allow users to access services from remote
   locations.  In such cases the profile data may have to be obtained
   from different profile sources: local network provider, device
   provider and SIP service provider.  This is indicated in Figure 3 .

       /   SIP    \
      |   Service  |                -> Provides 'user' profile
      |  Provider  |                   data (e.g., services
       \          /                    configuration)
         --------      --------
             |       /          \
             |      |   Device   |  -> Provides 'device' profile
             |      |  Provider  |     data (e.g., device specifics)
             |       \          /
             |         ---------
             |        /
             |       /    -------
             |      /   /  Local  \
             |     /   |  Network  |
             |    |    |  Provider | -> Provides 'local-network' profile
             |    |     \         /     data (e.g., bandwidth)
             |    |       -------
             |    |        /
             |    |       /
             |    |      |
       (   Local Network   )
            | Device |              -> Needs the 'local-network'
             --------                  and 'device' profile
             /     \
            /       \
          ------   ------
         |User A| |User B|          -> Users need 'user' profiles
          ------   ------
                    Figure 3: Complex Deployment Model

   In either case, Providers need to deliver to the device, profile data
   that is required to participate in their network.  Examples of
   profile data include the list of codecs that can be used and the SIP
   proxies to connect to for services.  Pre-configuration of such
   information is one option if the device is always served by the same
   set of Providers.  In all other cases, the profile delivery needs to
   be automated and consistent across Providers.  Given the presence of
   a number of large deployments where pre-configuration is neither
   desired nor optimal, there is a need for a common configuration
   framework such as the one described in this document.

   Further, the former deployment model can be accomplished by the
   device obtaining profile data from a single provider.  However, the
   latter deployment model requires the device to obtain profile data
   from different providers.  To address either deployment, or any
   variation in between, one needs to allow for profile delivery via
   one, or more, Providers.  The framework accomplishes this by
   specifying multiple profile types and a set of profile delivery
   stages to obtain them.  These are introduced in the sub-sections to

3.3.  Profile Types

   The framework handles the presence of potentially different Providers
   by allowing for multiple profile types.  Clients request each profile
   separately, and obtain them from the same, or different, Providers.
   A deployment can also choose to pre-configure the device to request
   only a subset of the specified profile types.  The framework
   specifies three basic profile types, as follows:

   Local Network Profile:  contains configuration data related to the
      local network to which a device is directly connected, provided by
      the Local Network Provider.

   Device Profile:  contains configuration data related to a specific
      device, provided by the Device Provider.

   User Profile:  contains configuration data related to a specific
      User, as required to reflect that user's preferences and the
      particular services subscribed to.  It is provided by the SIP
      Service Provider.

   Additional profile types may also be specified.

   PDSs and devices will implement all the three profile types.  A
   device that has not been configured otherwise will try to obtain all
   the three profile types, in the order specified by this framework.  A
   device being bootstrapped SHOULD request the device profile type (see
   Section 5.3.1 for more information).  The device can be configured
   with a different behavior via profile data previously obtained by the
   device, or by using other means such as pre-configuration or manual
   configuration.  The data models associated with each profile type are
   out of scope for this document.  Follow-on standardization activities
   are expected to specify such data models.

3.4.  Profile delivery stages

   The framework specified in this document requires a device to
   explicitly request profiles.  It also requires one or more PDSs which
   provide the profile data.  The processes that lead a device to obtain
   profile data, and any subsequent changes, can be explained in three
   stages, termed the profile delivery stages.

   Profile Enrollment:  the process by which a device requests, and if
      successful, enrolls with a PDS capable of providing a profile.  A
      successful enrollment is indicated by a notification containing
      the profile information (contents or content indirection
      information).  Depending on the request, this could also result in
      a subscription to notification of profile changes.

   Profile Content Retrieval:  the process by which a device retrieves
      profile contents, if the profile enrollment resulted in content
      indirection information.

   Profile Change Notification:  the process by which a device is
      notified of any changes to an enrolled profile.  This may provide
      the device with modified profile data or content indirection

4.  Use Cases

   This section provides a small, non-comprehensive set of
   representative use cases to further illustrate how this Framework can
   be utilized in SIP deployments.  The first use case is simplistic in
   nature, whereas the second is relatively complex.  The use cases
   illustrate the effectiveness of the framework in either scenario.

   For Security Considerations please refer to Section 5 and Section 9.

4.1.  Simple Deployment Scenario

   Description: Consider a deployment scenario (e.g., a small private
   enterprise) where a participating device implements this framework
   and is configured, using previously obtained profile data, to request
   only the device profile.  Assume that the device operates in the same
   network as the PDS (i.e., there is no NAT) and it obtains its IP
   configuration using DHCP.  Typical communication between the device
   and the PDS will traverse one or more SIP proxies, but is not
   required, and is omitted in this illustration.

   Figure 4 illustrates the sequence of events that include device
   startup and a successful profile enrollment for the device profile
   that results in device profile data.  It then illustrates how a
   change in the profile data is delivered via Profile Change

    +--------+                           |  Provider's Network  |
    | Device |                           |                      |
    |        |                           |                      |
    +--------+                           |  DHCP        PDS     |
         |                                   |          |
    (A)  |<============== DHCP =============>|          |
         |                                              |
         |                                              |
         |                                              |
    (B)  |<=========== Profile Enrollment  ============>|
         |                                              | Profile data
         |                                              | is modified
         |                                              |
    (C)  |<============ Profile Change  ================|
         |               Notification                   |
         |                                              |
         |                                              |
                           Figure 4: Use Case 1

   The following is an explanation of the interactions in Figure 4.
   (A)  Upon initialization, the device obtains IP configuration
        parameters such as IP address using DHCP.
   (B)  The device requests profile enrollment for the device profile.
        Successful enrollment provides it with a notification containing
        the device profile data.
   (C)  Due to a modification of the device profile, a profile change
        notification is sent across to the device, along with the
        modified profile.

4.2.  Devices supporting multiple users from different Service Providers

   Description: Consider a single device that allows multiple users to
   obtain services from different SIP Service Providers, e.g., a kiosk
   at an airport.

   The following assumptions apply:
   o    Provider A is the Device and Local Network Provider for the
        device, and the SIP Service Provider for user A; Provider B is
        the SIP Service Provider for user B.
   o    Profile enrollment always results in content indirection
        information requiring profile content retrieval.
   o    Communication between the device and the PDSs is facilitated via
        one or more SIP proxies (only one is shown in the illustration).

   Figure 4 5 illustrates the use case and highlights the communications
   relevant to the framework specified in this document.

     User User
       A   B        +----------------------+  +----------------------+
    +--------+      |       Provider       |  |       Provider       |
    | Device |      |           A          |  |          B           |
    |        |      |                      |  |                      |
    +--------+      | DHCP    PROXY   PDS  |  |  PROXY        PDS    |
                    +----------------------+  +----------------------+
         |              |        |      |          |           |
     (A) |<====DHCP====>|        |      |          |           |
         |                       |      |          |           |
         |                       |      |          |           |
         |  Profile Enrollment   |      |          |           |
     (B) |<local-network profile>|<====>|          |           |
         |   <<Profile content retrieval>>
         |  Profile Enrollment   |      |          |           |
     (C) |<== device profile ==> |<====>|          |           |
         |   <<Profile content retrieval>>
             [[User A obtains services]]

         |   Profile Enrollment  |      |          |           |
     (D) |<= user profile (A) => |<====>|          |           |
         |                       |      |          |           |
         |   <<Profile content retrieval>>
             [[User B obtains services]]

         |            Profile Enrollment           |           |
     (E) |<=========== user profile (B) ==========>|<=========>|
         |                                         |           |
         |   <<Profile content retrieval>>
                           Figure 5: Use Case 2

   The following is an explanation of the interactions in Figure 5.
   (A)  Upon initialization, the device obtains IP configuration
        parameters using DHCP.  This also provides the local domain
        information to help with local-network profile enrollment.
   (B)  The device requests profile enrollment for the local network
        profile.  It receives an enrollment notification containing
        content indirection information from Provider A's PDS.  The
        device retrieves the profile (this contains useful information
        such as firewall port restrictions and available bandwidth).
   (C)  The device then requests profile enrollment for the device
        profile.  It receives an enrollment notification resulting in
        device profile content retrieval.  The device initializes the
        user interface for services.
   (D)  User A with a pre-existing service relationship with Provider A
        attempts communication via the user Interface.  The device uses
        the user supplied information (including any credential
        information) and requests profile enrollment for user A's
        profile.  Successful enrollment and profile content retrieval
        results in services for user A.
   (E)  At a different point in time, user B with a service relationship
        with Provider B attempts communication via the user Interface.
        It enrolls and retrieves user B's profile and this results in
        services for user B.

   The discovery mechanisms for profile enrollment described by the
   framework, or the profile data themselves, can result in outbound
   proxies that support devices behind NATs, using procedures specified
   in [I-D.ietf-sip-outbound].

5.  Profile Delivery Framework

   This section specifies the profile delivery framework.  It provides
   the requirements for the three profile delivery stages introduced in
   Section 3.4 and presents the associated security requirements.  It
   also presents considerations such as back-off and retry mechanisms.

5.1.  Profile delivery stages

   The three profile delivery stages - enrollment, content retrieval and
   change notification - apply separately to each profile type specified
   for use with this framework.  The following sub-sections provide the
   requirements associated with each stage.

5.1.1.  Profile Enrollment

   Profile enrollment is the process by means of which a device
   requests, and receives, profile data.  Each profile type specified in
   this document requires an independent enrollment request.  However, a
   particular PDS can support enrollment for one or more profile types.

   Profile enrollment consists of the following operations, in the
   specified order.

   Enrollment request transmission

      Profile enrollment is initiated when the device transmits a SIP
      SUBSCRIBE request [RFC3265] for the 'ua-profile' event package,
      specified in Section 6.  The profile being requested is indicated
      using the 'profile-type' parameter.  The device MUST transmit the
      SIP SUBSCRIBE message via configured outbound proxies for the
      destination domain, or in accordance with RFC 3263 [RFC3263].

      The device needs certain data to create an enrollment request,
      form a Request URI, and authenticate to the network.  This
      includes the profile provider's domain name, identities and
      credentials.  Such data can be "configured" during device
      manufacturing, by the user, or via profile data enrollment (see
      Section 5.3.1).  The data can also be "discovered" using the
      procedures specified by this framework.  The "discovered" data can
      be retained across device resets (but not across factory resets)
      and such data is referred to as "cached".  Thus, data can be
      configured, discovered or cached.  The following requirements

      *  If the device is configured with a specific domain name (for
         the local network provider or device provider), it MUST NOT
         attempt "discovery" of the domain name.  This is the case when
         the device is pre-configured (e.g., via a user interface) to be
         managed by specific entities.
      *  The device MUST only use data associated with the provider's
         domain in an enrollment request.  As an example, when the
         device is requesting a local-network profile in the domain
         '', it cannot present a user AoR associated with the
         local domain ''.
      *  The device SHOULD adhere to the following order of data usage:
         configured, cached and discovered.  An exception is when the
         device is explicitly configured to use a different order.

      Upon failure to obtain the profile using any methods specified in
      this framework, the device MAY provide a user interface to allow
      for user intervention.  This can result in temporary, one-time
      data to bootstrap the device.  Such temporary data is not
      considered to be "configured" and is SHOULD NOT not expected to be cached across
      resets.  The configuration obtained using such data MAY provide
      the configuration data required for the device to continue
      functioning normally.

      Devices attempting enrollment MUST comply with the SIP-specific
      event notification specified in [RFC3265], the event package
      requirements specified in Section 6.2, and the security
      requirements specified in Section 5.2.

   Enrollment request admittance

      A PDS or a SIP proxy will receive a transmitted enrollment
      request.  If a SIP infrastructure element receives the request, it
      will relay it to the authoritative proxy for the domain indicated
      in the Request-URI (the same way it would handle any other
      SUBSCRIBE message).  The authoritative proxy is required to
      examine the request (e.g., event package) and transmit it to a PDS
      capable of addressing the profile enrollment request.

      A PDS receiving the enrollment request SHOULD respond to the
      request, or proxy it to a PDS that can respond.  An exception to
      responding or proxying the request is when a policy prevents a
      response (e.g., recognition of a DoS attack, an invalid device,
      etc.).  The PDS then verifies the identity presented in the
      request and performs any necessary authentication.  Once
      authentication is successful, the PDS MUST either admit or reject
      the enrollment request, based on applicable authorization
      policies.  A PDS admitting the enrollment request indicates it via
      a 2xx-class response, as specified in [RFC3265].

      Refer to Section 6.6 and Section 5.2 for more information on
      subscription request handling and security requirements,

   Enrollment request acceptance

      A PDS that admits the enrollment request verifies applicable
      policies, identifies the requested profile data and prepares a SIP
      NOTIFY message to the device.  Such a notification can either
      contain the profile data or contain content indirection
      information that results in the device performing profile content
      retrieval.  The PDS then transmits the prepared SIP notification.
      When the device successfully receives and accepts the SIP
      notification, profile enrollment is complete.

      When it receives the SIP NOTIFY message, indicating successful
      profile enrollment, the device SHOULD make the new profile
      effective within the specified time frame, as described in
      Section 6.2.  The exception is when the profile data is delivered
      via content indirection, and the device cannot obtain the profile
      data within the specified time frame.

      Once profile enrollment is successful, the PDS MUST consider the
      device enrolled for the specific profile, for the duration of the

5.1.2.  Content Retrieval

   A successful profile enrollment leads to an initial SIP notification,
   and may result in subsequent change notifications.  Each of these
   notifications can either contain profile data, or content indirection
   information.  If it contains content indirection information, the
   device is required to retrieve the profile data using the specified
   content retrieval protocols.  This process is termed profile content
   retrieval.  For information regarding the use of the SIP NOTIFY
   message body please refer to Section 6.5.

   Devices and PDSs implementing this framework MUST implement two
   content retrieval protocols: HTTP and HTTPS as specified in [RFC2616]
   and [RFC2818], respectively.  Future enhancements or usage of this
   framework may specify additional or alternative content retrieval
   protocols.  For security requirements and considerations please refer
   to Section 5.2.

5.1.3.  Change Notification

   Profile data can change over time.  Changes can be initiated by
   various entities (e.g., via the device, back-office components and
   end-user web interfaces) and for various reasons (e.g., change in
   user preferences and modifications to services).  Profiles may also
   be shared by multiple devices simultaneously.  When a profile is
   changed the PDS MUST inform all the devices currently enrolled for
   the specific profile.  This process of informing a device of any
   changes to the profile that it is currently enrolled for is termed
   change notification.

   The PDS provides change notification using a SIP notification (SIP
   NOTIFY message as specified in [RFC3265]).  The SIP notification may
   provide the changes, a revised profile or content indirection which
   contains a pointer to the revised data.  When a device successfully
   receives a profile change notification for an enrolled profile, it
   MUST act upon the changes prior to the expiration of the
   'effective-by' parameter.

   For NOTIFY content please refer to Section 6.5.

5.1.4.  Enrollment Data and Caching

   The requirements for the contents of the SIP SUBSCRIBE used to
   request profile enrollment are described in this section.  The data
   required can be configured, cached or discovered - depending on the
   profile type.  If the data is not configured, the device MUST use
   relevant cached data or proceed with data discovery.  This section
   describes the requirements for creating a SIP SUBSCRIBE for
   enrollment, the caching requirements and how data can be discovered.  Local-Network Profile

   To create a Subscription URI to request the local-network profile a
   device needs the local network domain name, the device identifier and
   optionally a user AoR with associated credentials (if one is
   configured).  Since the device can be potentially initialized in a
   different local-network each time, it SHOULD NOT cache the local
   network domain, the SIP subscription URI or the local-network profile
   data across resets.  An exception to this is when the device can
   confirm that it is reinitialized in the same network (using means
   outside the scope of this document).  Thus, in most cases, the device
   needs to discover the local network domain name.  The device
   discovers this by establishing IP connectivity in the local network
   (such as via DHCP or pre-configured IP information).  Once
   established, the device MUST attempt to use the local network domain
   obtained via pre-configuration, if available.  If it is not pre-
   configured, it MUST employ dynamic discovery using DHCPv4 ([RFC2132],
   Domain Name option) or DHCPv6 ([RFC4704]).  Once the local network
   domain is obtained, the device creates the SIP SUBSCRIBE for
   enrollment as described below.
   o  The device MUST NOT populate the user part of the Request URI.
      The device MUST set the host portion of the Request URI to the
      dot-separated concatenation of "_sipuaconfig" and the local
      network domain (see example below).
   o  If the device has been configured with a user AoR for the local
      network domain (verified as explained in Section 5.2) it MUST use
      it to populate the "From" field, unless configured not to (due to
      privacy concerns, for example).  Otherwise, the device MUST set
      the "From" field to a value of "anonymous@anonymous.invalid".

   o  The device MUST include the +sip.instance parameter within the
      'Contact' header, as specified in [I-D.ietf-sip-outbound].  The
      device MUST ensure that the value of this parameter is the same as
      that included in any subsequent profile enrollment request.

   For example, if the device requested and received the local domain
   name via DHCP to be:, then the local-network
   Profile SUBSCRIBE Request URI would look like:

   The local-network profile SUBSCRIBE Request URI does not have a user
   part so that the URI is distinct between the "local" and "device"
   URIs when the domain is the same for the two.  This provides a means
   of routing to the appropriate PDS in domains where there are distinct

   The From field is populated with the user AoR, if available.  This
   allows the local network provider to propagate user-specific profile
   data, if available.  The "+sip.instance" parameter within the
   "Contact" header is set to the device identifier or specifically, the
   SIP UA instance.  Even though every device may get the same (or
   similar) local-network Profile, the uniqueness of the "+sip.instance"
   parameter provides an important capability.  Having unique instance
   ID fields allows the management of the local network to track devices
   present in the network and consequently also manage resources such as
   bandwidth allocation.  Device Profile Type

   Once associated with a device, the device provider is not expected to
   change frequently.  Thus, the device is allowed to, and SHOULD cache
   the Subscription URI for the device profile upon successful
   enrollment.  Exceptions include cases where the device identifier has
   changed (e.g., new network card), device provider information has
   changed (e.g., user initiated change) or the device cannot obtain its
   profile using the Subscription URI.  Thus, when available, the device
   MUST use a cached Subscription URI.  If no cached URI is available
   then it needs to create a Subscription URI.  To create a Subscription
   URI, the device needs a device identity and the device provider's
   domain name.  Unless already configured, the device needs to discover
   the necessary information and form the subscription URI.  In such
   cases, the following requirements apply for creating a Subscription
   URI for requesting the device profile:

   o  The device MUST populate the user part of the Request URI with the
      device identifier.  The device MUST set the host portion of the
      Request URI to the domain name of the device provider.  The device
      identifier format is explained in detail later in this section.
   o  The device MUST set the "From" field to a value of anonymous@
      <device provider's domain>.
   o  The device MUST include the +sip.instance parameter within the
      'Contact' header, as specified in [I-D.ietf-sip-outbound].  The
      device MUST use the same value as the one presented while
      requesting the local-network profile.

   Note that the discovered AoR for the Request URI can be overridden by
   a special, provisioned, AoR that is unique to the device.  In such
   cases, the provisioned AoR is used to form the Request URI and to
   populate the From field.

   If the device is not configured with an AoR, and needs a domain name
   to populate the Request URI and the From field, it can either use a
   configured domain name, if available, or discover it.  The options to
   discover are described below.  The device MUST use the results of
   each successful discovery process for one enrollment attempt, in the
   order specified below.

   o  Option 1: Devices that support DHCP MUST attempt to obtain the
      domain name of the outbound proxy during the DHCP process, using
      the DHCP option for SIP servers defined in [RFC3361] or [RFC3319]
      (for IPv4 and IPv6 respectively).
   o  Option 2: Devices that support DHCP MUST attempt to obtain the
      local IP network domain during the DHCP process (refer to
      [RFC2132] and [RFC4704] ).
   o  Option 3: Devices MUST use the local network domain name
      (configured or discovered to retrieve the local-network profile),
      prefixing it with the label "_sipuaconfig".

   If the device needs to create a subscription URI and needs to use its
   device identifier, it MUST use the UUID-based URN representation as
   specified in [RFC4122].  The following requirements apply:
   o  When the device has a non-alterable MAC address it SHOULD use
      version 1 UUID representation with the timestamp and clock
      sequence bits set to a value of '0'.  This will allow for easy
      recognition, and uniqueness of MAC address based UUIDs.  An
      exception is the case where the device supports independent device
      configuration for more than one SIP UA.  An example would be
      multiple SIP UAs on the same platform.
   o  If the device cannot use a non-alterable device identifier, it
      SHOULD use an alternative non-alterable device identifier.  For
      example, the International Mobile Equipment Identity (IMEI) for
      mobile devices.

   o  If the device cannot use a non-alterable MAC Address, it MUST be
      use the same approach as defining a user agent Instance ID in
   o  Note: when the URN is used as the user part of the Request URI, it
      MUST be URL escaped since the colon (":") is not a legal character
      in the user part of an addr-spec ([RFC4122]), and must be escaped.

         For example, the instance ID:

         would be escaped to look as follows in a URI:


         The ABNF for the UUID representation is provided in [RFC4122]  User Profile Type

   To create a Subscription URI to request the user profile on behalf of
   a user, the device needs to know the user's AoR.  This can be
   statically or dynamically configured on the device (e.g., user input,
   or propagated as part of the device profile).  Similar to device
   profiles, the content and propagation of user profiles may differ,
   based on deployment scenarios (i.e., users belonging to the same
   domain may - or may not - be provided the same profile).  To create a
   subscription URI, the following rules apply:

   o  The device MUST set the Request URI to the user AoR.
   o  The device MUST populate the "From" field with the user AoR.

   An authoritative SIP proxy for a SIP provider's network that receives
   a profile enrollment request for the user profile type will route
   based on the Event Header field values, thus allowing a subscription
   to the user's AoR to be routed to the appropriate PDS.

5.2.  Securing Profile Delivery

   Profile data can contain sensitive information that needs to be
   secured, such as identities and credentials.  Security involves
   authentication, message integrity and privacy.  Authentication is the
   process by which you verify that an entity is who it claims to be,
   such as a user AoR presented during profile enrollment.  Message
   integrity provides the assurance that the message contents
   transmitted between two entities, such as between the PDS and the
   device, has not been modified during transit.  Privacy ensures that
   the message contents have not been subjected to monitoring by
   unwanted elements during transit.  Authentication and message
   integrity are required to ensure that the profile contents were
   received by a valid entity, from a valid source, and without any
   modifications during transit.  For profiles that contain sensitive
   data, privacy is also required.

   For an overview of potential security threats, refer to Section 9.
   For information on how the device can be configured with identities
   and credentials, refer to Section 5.3.1.  The following subsections
   provide the security requirements associated with each profile
   delivery stage, and applies to each of profile types specified by
   this framework.

5.2.1.  Securing Profile Enrollment

   Profile enrollment may result in sensitive profile data.  In such
   cases, the PDS MUST authenticate the device, except during the
   bootstrapping scenario when the device does not have existing
   credentials (see Section 5.3.1 for more information on
   bootstrapping).  Additionally, the device MUST authenticate the PDS
   to ensure that it is obtaining sensitive profile data from a valid
   PDS, except in the bootstrapping scenario.

   To authenticate a device that has been configured with identities and
   credentials as specified in Section 5.3.1 and support profiles
   containing sensitive profile data (refer to Section 5.3.4), devices
   and PDSs MUST support Digest Authentication as specified in
   [RFC3261].  Future enhancements may provide other authentication
   methods such as authentication using X.509 certificates.  For the
   device to authenticate the PDS, the device MUST mutually authenticate
   with the PDS during digest authentication (device challenges the PDS,
   which responds with the Authorization header).  Transmission of
   sensitive profile data also requires message integrity.  This can be
   accomplished by configuring the device with, or by ensuring that the
   discovery process during profile enrollment provides, a SIPS URI
   resulting in TLS establishment ([RFC4346]). ([RFC5246]).  TLS also prevents
   offline dictionary attacks when digest authentication is used.  Thus,
   in the absence of TLS, the device MUST NOT respond to any
   authentication challenges.  It is to be noted that the digest
   credentials used for obtaining profile data via this framework may,
   or may not, be the same as that used for SIP registration (see
   Section 5.3.1).

   When the PDS challenges a profile enrollment request, and it fails,
   the PDS MAY refuse enrollment or provide profile data without the
   user-specific information (e.g., to bootstrap a device as indicated
   in Section 5.3.1).  If the device challenges, but fails to
   authenticate the PDS, it MUST reject the initial notification and
   retry the profile enrollment process.  If the device is configured
   with, or discovers, a SIPS URI but TLS establishment fails because
   the next-hop SIP entity does not support TLS, the device SHOULD
   attempt other resolved next-hop SIP entities.  When the device
   establishes TLS with the next-hop entity, the device MUST use the
   procedures specified in [RFC2818], Section 3.1, for authentication,
   unless it does not have any configured information (e.g., CA
   certificate) to perform authentication (like prior to bootstrapping).
   The 'Server Identity' for authentication is always the domain of the
   next-hop SIP entity.  If the device attempts validation, and it
   fails, it MUST reject the initial notification and retry profile
   enrollment.  In the absence of a SIPS URI for the device and a
   mechanism for mutual authentication, the PDS MUST NOT present any
   sensitive profile data in the initial notification, except when the
   device is being bootstrapped.  It MAY still use content indirection
   to transmit sensitive profile data.

   When a device is being provided with bootstrapping profile data
   within the notification, and it contains sensitive information, the
   SIP Identity header SHOULD be used as specified in [RFC4474].  This
   helps with devices that MAY be pre-configured with certificates to
   validate bootstrapping sources (e.g., list of allowed domain
   certificates, or a list of root CA certificates using PKI).  When the
   SIP Identity header is used, the PDS MUST set the host portion of the
   AoR in the 'From' header to the Provider's domain (the user portion
   is a entity-specific identifier).  If the device is capable of
   validating the SIP Identity, and it fails, it MUST reject
   bootstrapping profile data.

5.2.2.  Securing Content Retrieval

   Initial or change notifications following a successful enrollment can
   provide a device with the requested profile data, or use content
   indirection to direct it to a PCC that can provide the profile data.
   This document specifies HTTP and HTTPS as content retrieval

   If the profile is provided via content indirection and contains
   sensitive profile data then the PDS MUST use a HTTPS URI for content
   indirection.  PCCs and devices MUST NOT use HTTP for sensitive
   profile data, except for bootstrapping a device via the device
   profile.  A device MUST authenticate the PCC as specified in
   [RFC2818], Section 3.1.  A device that is being provided with profile
   data that contains sensitive data MUST be authenticated using digest
   authentication as specified in [RFC2617], with the exception of a
   device that is being bootstrapped for the first time via the device
   profile.  The resulting TLS channel also provides message integrity
   and privacy.

5.2.3.  Securing Change Notification

   If the device requested enrollment via a SIP subscription with a non-
   zero 'Expires' parameter, it can also result in change notifications
   for the duration of the subscription.  For change notifications
   containing sensitive profile data, this framework RECOMMENDS the use
   of the SIP Identity header as specified in [RFC4474].  When the SIP
   Identity header is used, the PDS MUST set the host portion of the AoR
   in the 'From' header to the Provider's domain (the user portion is a
   entity-specific identifier).  This provides header and body integrity
   as well.  However, for sensitive profile data requiring privacy, if
   the contact URI to which the NOTIFY request is to be sent is not
   SIPS, the PDS MUST use content indirection.  Additionally, the PDS
   MUST also use content indirection for notifications containing
   sensitive profile data, when the profile enrollment was not

5.3.  Additional Considerations

   This section provides additional considerations such as details on
   how a device obtains identities and credentials, backoff and retry
   methods, guidelines on profile data and additional profile types.

5.3.1.  Bootstrapping Identities and Credentials

   When requesting a profile the device can provide an identity (i.e., a
   user AoR), and contain associated credentials for authentication.  To
   do so, the device needs to obtain this information via bootstrapping.
   This can be accomplished in one of the following ways:


      The device may be pre-configured with identities and associated
      credentials, such as a user AoR and digest password.

   Out-of-band methods

      A device or Provider may provide hardware- or software-based
      credentials such as SIM cards or Universal Serial Bus (USB)

   End-user interface

      The end-user may be provided with the necessary identities and
      credentials.  The end-user can then configure the device (using a
      user interface), or present when required (e.g., IM login screen).

   Using this framework

      When a device is initialized, even if it has no pre-configured
      information, it can request the local-network and device profiles.
      For purposes of bootstrapping, this framework recommends that the
      device profile provide one of the following to bootstrap the
      *  Profile data that allows the end-user to communicate with the
         device provider or SIP service provider using non-SIP methods.
         For example, the profile data can direct the end-user to a web
         portal to obtain a subscription.  Upon obtaining a successful
         subscription, the end-user or the device can be provided with
         the necessary identities and credentials.
      *  Content indirection information to a PCC that can provide
         identities and credentials.  As an example, consider a device
         that has a X.509 certificate that can be authenticated by the
         PCC.  In such a case, the PCC can use HTTPS to provide
         identities and associated credentials.
      *  Profile data containing identities and credentials that can be
         used to bootstrap the device (see Section 5.3.4 for profile
         data recommendations).  This can be used in cases where the
         device is initialized for the first time, or after a factory
         reset.  This can be considered only in cases where the device
         is initialized in the Provider's network, for obvious security

   Additionally, AoRs are typically known by PDSs that serve the domain
   indicated by the AoR.  Thus, devices can only present the configured
   AoRs in the respective domains.  An exception is the use of federated
   identities.  This allows a device to use a user's AoR in multiple
   domains.  Further even within the same domain, the device's domain
   proxy and the PDS may be in two different realms, and as such may be
   associated with different credentials for digest authentication.  In
   such cases, multiple credentials may be configured, and associated
   with the realms in which they are to be used.  This framework
   specifies only digest authentication for profile enrollment and the
   device is not expected to contain any other credentials.  For profile
   retrieval using content indirection, the device will need to support
   additional credentials such as X.509 certificates (for TLS).  Future
   enhancements can specify additional credential types for profile
   enrollment and retrieval.

5.3.2.  Profile Enrollment Request Attempt

   A state diagram representing a device requesting any specific profile
   defined by this framework is shown in Figure 6.

                                | Initialize |
                               |   Prepare   |
                    +--------->|  Enrollment |<------------------+
                    |          |   Request   |                   |
                    |          +------+------+                   |
             +------+------+          |                          |
             |   Failure   | Enroll. Req. prepared               |
         +-->|  Handling & |      /Send Req                      |
         |   |   Delay     |          |                          |
         |   +-------------+          V                          |
         |       ^    ^        +-------------+                   |
         |       |    |        |    Await    |                   |
         |       |    +--------+  Enrollment |                   |
         |       |    Timeout, |  acceptance |                   |
         |       |   non-2xx/- +------+------+                   |
         |       |                    |                          |
         |   Timeout            200 OK/-                    Enrollment
         |  /Terminate                |                       Timeout/-
         |   Enrollment               V                          |
         |       |            +--------------+                   |
         |       |            |  Enrollment  |                   |
         |       +------------+   accepted   |                   |
    Retries Exceeded          |(await NOTIFY)|                   |
   /Retry Enrollment          +---+------+---+                   |
         |                        |      |                       |
         |                        |      |                       |
         |   NOTIFY w. Content Ind|      |  NOTIFY w. Profile    |
         |     /Retrieve Profile  |      |  /Accept Profile      |
         |           +------------+      +------------+          |
         |           |                                |          |
         |           V                                V          |
         |     +------------+                   +------------+   |
         +-----+ Retrieving |    Retrieved      | Enrollment +---+
            ,->|   Profile  +--/Apply Profile-->| Successful |
           /   |            |                   |(monitoring)|<--.
      Timeout  +--+---------+                   +--+----+----+    :
      /Retry      ;      ^                         |    :         ;
           `------'      |   NOTIFY w. Cont.Ind    |    `-------'
                         +---/Retrieve Profile-----+   NOTIFY w. Profile
                                                          /Apply Profile

                      Figure 6: Device State Diagram

   As a reminder:
   o  The timeout for SIP messages is specified by [RFC3261].  In the
      cases where this is not specified such as the timeout to wait for
      the initial notification during profile enrollment, it is left to
      device implementations or future protocol enhancements.
   o  The timeout for profile retrieval using content indirection will
      be as specified by profile retrieval protocols employed.  If none
      exists, it is left to device implementations.

   In addition, since profile enrollment is a process unique to this
   framework, the device MUST follow the enrollment attempt along with
   exponential backoff and retry mechanisms as indicated in Figure 7.

     Function for Profile Enrollment ()

        Init Function: Iteration i=0

        Loop 1: Attempt

             Loop 2: For each SIP Subscription URI

                  Loop 3: For each next-hop SIP entity

                     - Prepare & transmit Enrollment Request

                     - Await Enrollment Acceptance and initial NOTIFY

                     + If the profile enrollment is successful
                       = Exit this function()

                     + If profile enrollment fails due to an explicit
                       failure or a timeout as specified in RFC3261
                       = Continue with the next-hop SIP entity (Loop 3)

                  End Loop: Loop 3

             End Loop: Loop 2

             (Note: If you are here, profile enrollment did not succeed)

             + Is any valid cached profile data available?
               = If yes, use it and continue with Loop 1

             + If the enrollment request is for a non-mandatory profile
               = Start profile enrollment for the next profile,
                 if applicable

             - Delay for 2^i*(64*T1); -- this is exponential backoff

             - increment i;

             - If i>8, reset i=8;

       End loop: Loop 1

   End Function()

            Figure 7: Profile Enrollment Attempt (pseudo-code)

   The pseudo-code above (Figure 7) allows for cached profiles to be
   used.  However, any cached Local Network profile MUST NOT be used
   unless the device can ensure that it is in the same local network
   which provided the cached data.  This framework does not provide any
   procedures for local network recognition.  Any cached device and user
   profiles MUST only be used in domains that they are associated with.
   For example, a cached device profile is used only when the associated
   domain matches the current device provider's domain.  If a PDS wants
   to invalidate a profile it may do so by transmitting a NOTIFY with an
   'empty profile', i.e., profile instance without any included data (if
   supported by the profile data model; not to be confused with an empty
   NOTIFY), or via an explicit profile data element that invalidates the
   data.  A device receiving such a NOTIFY MUST discard the applicable
   profile (i.e., it cannot even store it in the cache).  Additionally,
   if a factory reset is available and performed on a device, it MUST
   reset the device to its initial state prior to any configuration.
   Specifically, the device MUST set the device back to the state when
   it was originally distributed.

   The order of profile enrollment is important.  For the profiles
   specified in this framework, the device must enroll in the following
   default order: local-network, device and user.  The pseudo-code
   presented earlier (Figure 7) differentiates between 'mandatory' and
   'non-mandatory' profiles.  This distinction is left to profile data

   It is to be noted that this framework does not allow the devices to
   inform the PDSs of profile retrieval errors such as invalid data.
   Follow-on standardization activities are expected to address this

5.3.3.  Device Types

   The examples in this framework tend to associate devices with
   entities that are accessible to end-users.  However, this is not
   necessarily the only type of device that can utilize the specified
   Framework.  Devices can be entities such as SIP Phones or soft
   clients, with or without user interfaces (that allow for device
   Configuration), entities in the network that do not directly
   communicate with any users (e.g., gateways, media servers, etc) or
   network infrastructure elements e.g., SIP servers).

5.3.4.  Profile Data

   This framework does not specify the contents for any profile type.
   Follow-on standardization activities are expected to address profile
   contents.  However, the framework provides the following requirements
   and recommendations for profile data definitions:

   o  The device profile type SHOULD specify parameters to configure the
      identities and credentials for use in scenarios such as
      bootstrapping (see Section 5.3.1) and run-time modifications to
      identities and credentials.  This framework recommends the device
      profile to provide the identities and credentials due to a couple
      of reasons.  The local-network profile may not always be
      available, and even if present, may not be controlled by the
      device provider who controls device configuration to provide
      services.  Further, the device may not have any users configured
      prior to being bootstrapped, resulting in an absence of user
      profile requests.  However, this framework does not prevent other
      profile types from providing identities and credentials to meet
      deployment needs.  For example, the user profile can contain
      identities and credentials for communicating with specific
   o  Each profile MUST clearly identify if it may contain any sensitive
      data.  Such profiles MUST also identify the data elements that are
      considered sensitive, i.e., data that cannot be compromised.  As
      an example, a device profile definition may identify itself as
      containing sensitive data and indicate data such as device
      credentials to be sensitive.
   o  When the device receives multiple profiles, the contents of each
      profile type SHOULD only contain data relevant to the entity it
      represents.  As an example, consider a device that obtains all the
      defined profiles.  Information pertaining to the local network is
      contained in the 'local-network' profile and not the 'user'
      profile.  This does not preclude relevant data about a different
      entity from being included in a profile type, e.g., the 'device'
      profile type may contain information about the users allowed to
      access services via the device.  A profile may also contain
      starting information to obtain subsequent Profiles.
   o  Data overlap SHOULD be avoided across profile types, unless
      necessary.  If data overlap is present, prioritization of the data
      is left to data definitions.  As an example, the device profile
      may contain the list of codecs to be used by the device and the
      user Profile (for a user on the device) may contain the codecs
      preferred by the user.  Thus, the same data (usable codecs) is
      present in two profiles.  However, the data definitions may
      indicate that to function effectively, any codec chosen for
      communication needs to be present in both the profiles.

5.3.5.  Profile Data Frameworks

   The framework specified in this document does not address profile
   data representation, storage or retrieval protocols.  It assumes that
   the PDS has a PCC based on existing or other Profile Data Frameworks.

   While this framework does not impose specific constraints on any such
   framework, it does allow for the propagation of profile content to
   the PDS (specifically the PCC) from a network element or the device.
   Thus, Profile Data or Retrieval frameworks used in conjunction with
   this framework MAY consider techniques for propagating incremental,
   atomic changes to the PDS.  One means for propagating changes to a
   PDS is defined in XCAP ([RFC4825]).

5.3.6.  Additional Profile Types

   This document specifies three profile types: local-network, device
   and user.  However, there may be use cases for additional profile
   types. e.g., profile types for application specific profile data or
   to provide enterprise-specific policies.  Definition of such
   additional profile types is not prohibited, but considered out of
   scope for this document.  Such profile definitions MUST specify the
   order of retrieval with respect to all the other profiles such as the
   local-network, device and user profile types defined in this

5.3.7.  Deployment considerations

   The framework defined in this document was designed to address
   various deployment considerations, some of which are highlighted

   Provider relationships:
   o  The local network provider and the SIP service provider can often
      be different entities, with no administrative or business
      relationship with each other.
   o  There may be multiple SIP service providers involved, one for each
      service that a user subscribes to (telephony service, instant
      messaging, etc.); this Framework does not specify explicit
      behavior in such a scenario, but it does not prohibit its usage
   o  Each user accessing services via the same device may subscribe to
      different sets of services, from different Service Providers.

   User-device relationship:
   o  The relationship between devices and users can be many-to-many
      (e.g., a particular device may allow for many users to obtain
      subscription services through it, and individual users may have
      access to multiple devices).
   o  Each user may have different preferences for use of services, and
      presentation of those services in the device user interface.
   o  Each user may have different personal information applicable to
      use of the device, either as related to particular services, or
      independent of them.

5.4.  Support for NATs

   PDSs that support devices behind NATs, and devices that can be behind
   NATs can use procedures specified in [I-D.ietf-sip-outbound].  The
   Outbound proxies can be configured or discovered.  Clients that
   support such behavior MUST include the 'outbound' option-tag in a
   Supported header field value, and add the "ob" parameter as specified
   in [I-D.ietf-sip-outbound] within the SIP SUBSCRIBE for profile

6.  Event Package Definition

   The framework specified in this document proposes and specifies a new
   SIP Event Package as allowed by [RFC3265].  The purpose is to allow
   for devices to subscribe to specific profile types with PDSs and for
   the PDSs to notify the devices with the profile data or content
   indirection information.

   The requirements specified in [RFC3265] apply to this package.  The
   following sub-sections specify the Event Package description and the
   associated requirements.  The framework requirements are defined in
   Section 5.

6.1.  Event Package Name

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

6.2.  Event Package Parameters

   This package defines the following new parameters for the event
      "profile-type", "vendor", "model", "version", and "effective-by"

   The following rules apply:
   o  All the new parameters, with the exception of the "effective-by"
      parameter MUST only be used in SUBSCRIBE requests and ignored if
      they appear in NOTIFY requests.
   o  The "effective-by" parameter is for use in NOTIFY requests only
      and MUST be ignored if it appears in SUBSCRIBE requests.

   The semantics of these new parameters are specified in the following

6.2.1.  profile-type

   The "profile-type" parameter is used to indicate the token name of
   the profile type the user agent wishes to obtain and to be notified
   of subsequent changes.  This document defines three logical types of
   profiles and their token names.  They are as follows:

   local-network:  specifying the "local-network" type profile indicates
      the desire for profile data, and potentially, profile change
      notifications specific to the local network.

   device:  specifying the "device" type profile(s) indicates the desire
      for the profile data, and potentially, profile change notification
      that is specific to the device or user agent.

   user:  Specifying "user" type profile indicates the desire for the
      profile data, and potentially, profile change notification
      specific to the user.

   The profile type is identified in the Event header parameter:
   "profile-type".  A separate SUBSCRIBE dialog is used for each profile
   type.  Thus, the subscription dialog on which a NOTIFY arrives
   implies which profile's data is contained in, or referred to, by the
   NOTIFY message body.  The Accept header of the SUBSCRIBE request MUST
   include the MIME types for all profile content types for which the
   subscribing user agent wishes to retrieve profiles, or receive change

   In the following syntax definition using ABNF, EQUAL and token are
   defined in [RFC3261].  It is to be noted that additional profile
   types may be defined in subsequent documents.

   Profile-type   = "profile-type" EQUAL profile-value
   profile-value  =  profile-types / token
   profile-types  = "device" / "user" / "local-network"

   The "device", "user" or "local-network" token in the profile-type
   parameter may represent a class or set of profile properties.
   Follow-on standards defining specific profile contents may find it
   desirable to define additional tokens for the profile-type parameter.
   Also, additional content types may be defined along with the profile
   formats that can be used in the Accept header of the SUBSCRIBE to
   filter or indicate what data sets of the profile are desired.

6.2.2.  vendor, model and version

   The "vendor", "model" and "version" parameter values are tokens
   specified by the implementer of the user agent.  These parameters
   MUST be provided in the SUBSCRIBE request for all profile types.  The
   implementer SHOULD use their DNS domain name (e.g., as
   the value of the "vendor" parameter so that it is known to be unique.
   These parameters are useful to the PDS to affect the profiles
   provided.  In some scenarios it is desirable to provide different
   profiles based upon these parameters. e.g., feature property X in a
   profile may work differently on two versions of the same user agent.
   This gives the PDS the ability to compensate for or take advantage of
   the differences.  In the following ABNF defining the syntax, EQUAL
   and quoted-string are defined in [RFC3261].

   Vendor       =  "vendor" EQUAL quoted-string
   Model        =  "model" EQUAL quoted-string
   Version      =  "version" EQUAL quoted-string

6.2.3.  effective-by parameter

   The "effective-by" parameter in the Event header of the NOTIFY
   request specifies the maximum number of seconds before the user agent
   must attempt to make the new profile effective.  The "effective-by"
   parameter MAY be provided in the NOTIFY request for any of the
   profile types.  A value of 0 (zero) indicates that the subscribing
   user agent must attempt to make the profiles effective immediately
   (despite possible service interruptions).  This gives the PDS the
   power to control when the profile is effective.  This may be
   important to resolve an emergency problem or disable a user agent
   immediately.  If it is absent, the device SHOULD attempt to make the
   profile data effective at the earliest possible opportunity that does
   not disrupt any services being offered.  The "effective-by" parameter
   is ignored in all messages other than the NOTIFY request.  In the
   following ABNF, EQUAL and DIGIT are defined in [RFC3261].

   Effective-By =  "effective-by" EQUAL 1*DIGIT

6.2.4.  Summary of event parameters

   The following are example Event headers which may occur in SUBSCRIBE
   requests.  These examples are not intended to be complete SUBSCRIBE

   Event: ua-profile;profile-type=device;

   Event: ua-profile;profile-type=user;

   The following are example Event headers which may occur in NOTIFY
   requests.  These example headers are not intended to be complete
   SUBSCRIBE requests.

   Event: ua-profile;effective-by=0

   Event: ua-profile;effective-by=3600

   The following table shows the use of Event header parameters in
   SUBSCRIBE requests for the three profile types:

   profile-type || device | user | local-network
   vendor       ||   m    |  m   |        m
   model        ||   m    |  m   |        m
   version      ||   m    |  m   |        m
   effective-by ||        |      |

   m - mandatory
   s - SHOULD be provided
   o - optional

   Non-specified means that the parameter has no meaning and should be

   The following table shows the use of Event header parameters in
   NOTIFY requests for the three profile types:

   profile-type || device | user | local-network
   vendor       ||        |      |
   model        ||        |      |
   version      ||        |      |
   effective-by ||   o    |  o   |        o

6.3.  SUBSCRIBE Bodies

   This package defines no use of the SUBSCRIBE request body.  If
   present, it SHOULD be ignored.  Exceptions include future
   enhancements to the framework which may specify a use for the
   SUBSCRIBE request body.

6.4.  Subscription Duration

   The duration of a subscription is specific to SIP deployments and no
   specific recommendation is made by this Event Package.  If absent, a
   value of 86400 seconds (24 hours; 1 day) is RECOMMENDED since the
   presence (or absence) of a device subscription is not time critical
   to the regular functioning of the PDS.

   It is to be noted that a one-time fetch of a profile, without ongoing
   subscription, can be accomplished by setting the 'Expires' parameter
   to a value of Zero, as specified in [RFC3265].

6.5.  NOTIFY Bodies

   The framework specifying the Event Package allows for the NOTIFY body
   to contain the profile data, or a pointer to the profile data using
   content indirection.  For profile data delivered via content
   indirection, i.e., a pointer to a PCC, then the Content-ID MIME
   header, as described in [RFC4483] MUST be used for each Profile
   document URI.  At a minimum, the "http:" [RFC2616] and "https:"
   [RFC2818] URI schemes MUST be supported; other URI schemes MAY be
   supported based on the Profile Data Frameworks (examples include FTP
   [RFC0959], LDAP [RFC4510] and XCAP [RFC4825] ).

   A non-empty NOTIFY body MUST include a MIME type specified in the
   'Accept' header of the SUBSCRIBE.  Further, if the Accept header of
   the SUBSCRIBE included the MIME type message/external-body
   (indicating support for content indirection) then the PDS MAY use
   content indirection in the NOTIFY body for providing the profiles.

6.6.  Notifier Processing of SUBSCRIBE Requests

   A successful SUBSCRIBE request results in a NOTIFY with either
   profile contents or a pointer to it (via Content Indirection).  The
   SUBSCRIBE SHOULD be either authenticated, or transmitted over an
   integrity protected SIP communications channel.  Exceptions include
   cases where the identity of the Subscriber is unknown and the
   Notifier is configured to accept such requests.

   The Notifier MAY also authenticate SUBSCRIBE messages even if the
   NOTIFY is expected to only contain a pointer to profile data.
   Securing data sent via Content Indirection is covered in Section 9.

   If the profile type indicated in the "profile-type" Event header
   parameter is unavailable or the Notifier is configured not to provide
   it, the Notifier SHOULD return a 404 response to the SUBSCRIBE
   request.  If the specific user or device is unknown, the Notifier MAY
   accept the subscription, or else it may reject the subscription (with
   a 403 response).

6.7.  Notifier Generation of NOTIFY Requests

   As specified in [RFC3265], the Notifier MUST always send a NOTIFY
   request upon accepting a subscription.  If the device or user is
   unknown and the Notifier chooses to accept the subscription, the
   Notifier MAY either respond with profile data (e.g., default profile
   data) or provide no profile information (i.e., empty NOTIFY).

   If the identity indicated in the SUBSCRIBE request (From header) is a
   known identity and the requested profile information is available
   (i.e. as specified in the profile-type parameter of the Event
   header), the Notifier SHOULD send a NOTIFY with profile data.
   Profile data MAY be sent as profile contents or via Content
   Indirection (if the content indirection MIME type was included in the
   Accept header).  The Notifier MUST NOT use any scheme that was not
   indicated in the "schemes" Contact header field.

   The Notifier MAY specify when the new profiles must be made effective
   by the Subscriber by specifying a maximum time in seconds (zero or
   more) in the "effective-by" event header parameter.

   If the SUBSCRIBE was received over an integrity protected SIP
   communications channel, the Notifier SHOULD send the NOTIFY over the
   same channel.

6.8.  Subscriber Processing of NOTIFY Requests

   A Subscriber to this event package MUST adhere to the NOTIFY request
   processing behavior specified in [RFC3265].  If the Notifier
   indicated an effective time (using the "effective-by" Event Header
   parameter), the Subscriber SHOULD attempt to make the profiles
   effective within the specified time.  Exceptions include deployments
   that prohibit such behavior in certain cases (e.g., emergency
   sessions are in progress).  When profile data cannot be applied
   within the recommended time frame and this affects device behavior,
   any actions to be taken SHOULD be defined by the profile data
   definitions.  By default, the Subscriber is RECOMMENDED to make the
   profiles effective as soon as possible.

   When accepting content indirection, the Subscriber MUST always
   support "http:" or "https:" and be prepared to accept NOTIFY messages
   with those URI schemes.  If the Subscriber wishes to support
   alternative URI schemes they MUST each be indicated in the "schemes"
   Contact header field parameter as defined in [RFC4483].  The
   Subscriber MUST also be prepared to receive a NOTIFY request with no
   body.  The subscriber MUST NOT reject the NOTIFY request with no
   body.  The subscription dialog MUST NOT be terminated by a empty
   NOTIFY, i.e., with no body.

6.9.  Handling of Forked Requests

   This Event package allows the creation of only one dialog as a result
   of an initial SUBSCRIBE request as described in section 4.4.9 of
   [RFC3265].  It does not support the creation of multiple
   subscriptions using forked SUBSCRIBE requests.

6.10.  Rate of Notifications

   The rate of notifications for the profiles in this framework is
   deployment specific, but expected to be infrequent.  Hence, the Event
   Package specification does not specify a throttling or minimum period
   between NOTIFY requests

6.11.  State Agents

   State agents are not applicable to this Event Package.

7.  Examples

   This section provides examples along with sample SIP message bodies
   relevant to this framework.  Both the examples are derived from the
   use case illustrated in Section 4.1, specifically the request for the
   device profile.  The examples are informative only.

7.1.  Example 1: Device requesting profile

   This example illustrates the detailed message flows between the
   device and the SIP Service Provider's network for requesting and
   retrieving the profile (the flow uses the device profile as an

   The following are assumed for this example:

   o  Device is assumed to have established local network connectivity;
      NAT and Firewall considerations are assumed to have been addressed
      by the SIP Service Provider.
   o  Examples are snapshots only and do not illustrate all the
      interactions between the device and the Service Provider's network
      (and none between the entities in the SIP Service Provider's
   o  All SIP communication with the SIP Service Provider happens via a
      SIP Proxy.
   o  HTTP over TLS is assumed to be the Content Retrieval method used
      (any suitable alternative can be used as well).

   The flow diagram and an explanation of the messages follow.

    +--------+                        | SIP Service Provider |
    | Device |                        |                      |
    |(SIP UA)|                        |  SIP     PDS   HTTP  |
    +--------+                        | PROXY         Server |
                                      |                      |
         |                                |       |      |
         |                                |       |      |
         |          SUBSCRIBE             |       |      |
   (SReq)|--------device profile--------->|       |      |
         |                                |------>|      |
         |                                |200 OK |      |
         |            200 OK              |<------|      |
   (SRes)|<-------------------------------|       |      |
         |                                |       |      |
         |                                | NOTIFY|      |
         |    NOTIFY (Content Indirection)|<------|      |
   (NTFY)|<-------------------------------|       |      |
         |            200 OK              |       |      |
   (NRes)|------------------------------->|200 OK |      |
         |                                |------>|      |
         |                                               |
         |                                               |
         |                                               |
         |<<<<<<<<<<<<<  TLS establishment  >>>>>>>>>>>>>|
         |                                               |
         |                HTTP Request                   |
         |                                               |
         |                HTTP Response                  |
         |                                               |


      the device transmits a request for the 'device' profile using the
      SIP SUBSCRIBE utilizing the Event Package specified in this

      *    Note: Some of the header fields (e.g., SUBSCRIBE, Event, via)
           are continued on a separate line due to format constraints of
           this document.

   SUBSCRIBE sip:urn%3auuid%3a00000000-0000-1000-0000-00FF8D82EDCB
   Event: ua-profile;profile-type=device;vendor="";
   Call-ID: 3573853342923422@
   CSeq: 2131 SUBSCRIBE
   Contact: sip:urn%3auuid%3a00000000-0000-1000-0000-00FF8D82EDCB
   Via: SIP/2.0/TCP;
   Accept: message/external-body, application/x-z100-device-profile
   Content-Length: 0


      the SUBSCRIBE request is received by a SIP Proxy in the Service
      Provider's network which transmits it to the PDS.  The PDS accepts
      the response and responds with a 200 OK
      *    Note: The device and the SIP proxy may have established a
           secure communications channel (e.g., TLS).


      subsequently, the PDS transmits a SIP NOTIFY message indicating
      the profile location
      *  Note: Some of the fields (e.g., content-type) are continued on
         a separate line due to format constraints of this document.

 NOTIFY sip:urn%3auuid%3a00000000-0000-1000-0000-00FF8D82EDCB
        @ SIP/2.0
 Event: ua-profile;effective-by=3600
 Call-ID: 3573853342923422@
 CSeq: 322 NOTIFY
 Via: SIP/2.0/UDP;
 MIME-Version: 1.0
 Content-Type: message/external-body; access-type="URL";
               expiration="Mon, 01 Jan 2010 09:00:00 UTC";

 Content-Type: application/x-z100-device-profile
 Content-ID: <>


      Device accepts the NOTIFY message and responds with a 200 OK


      once the necessary secure communications channel is established,
      the device sends an HTTP request to the HTTP server indicated in
      the NOTIFY


      the HTTP server responds to the request via a HTTP response
      containing the profile contents

7.2.  Example 2: Device obtaining change notification

   The following example illustrates the case where a user (X) is
   simultaneously accessing services via two different devices (e.g.,
   Multimedia entities on a PC and PDA) and has access to a user
   interface that allows for changes to the user profile.

   The following are assumed for this example:
   o  The devices (A & B) obtain the necessary profiles from the same
      SIP Service Provider.
   o  The SIP Service Provider also provides a user interface that
      allows the user to change preferences that impact the user

   The flow diagram and an explanation of the messages follow.
   o  Note: The example only shows retrieval of user X's profile, but it
      may request and retrieve other profiles (e.g., local-network,

               -----           -----
              |User |_________| UI* | * = User Interface
              |  X  |         |     |
               -----           -----
             /       \
            /         \
           /           \              +----------------------+
    +--------+      +--------+        | SIP Service Provider |
    | Device |      | Device |        |                      |
    |    A   |      |    B   |        |  SIP     PDS   HTTP  |
    +--------+      +--------+        | PROXY         Server |
         |                                |       |      |
         |                                |       |      |
   (A-EX)|<=Enrolls for User X's profile=>|<=====>|      |
         |                                |       |      |
         |                                               |
   (A-RX)|<===Retrieves User X's profile================>|
         |                                               |
         |               |                |       |      |
         |               |  Enrolls for   |       |      |
         |         (B-EX)|<== User X's ==>|<=====>|      |
         |               |    profile     |       |      |
         |               |                |       |      |
         |               |                               |
         |         (B-RX)|<= Retrieves User X's profile=>|
         |                                               |
         |                       |                       |
         |                 (HPut)|---------------------->|
         |                       |                       |
         |                 (HRes)|<----------------------|
         |                                               |
         |                                |       |      |
         |                                | NOTIFY|      |
         |            NOTIFY              |<------|      |
   (A-NT)|<-------------------------------|       |      |
         |            200 OK              |       |      |
   (A-RS)|------------------------------->|200 OK |      |
         |                                |------>|      |
         |                                               |
         |               |                | NOTIFY|      |
         |               |    NOTIFY      |<------|      |
         |         (B-NT)|<---------------|       |      |
         |               |    200 OK      |       |      |
         |         (B-RS)|--------------->|200 OK |      |
         |               |                |------>|      |
         |                                               |
         |                                               |
   (A-RX)|<===Retrieves User X's profile================>|
         |                                               |
         |               |                               |
         |               |                               |
         |         (B-RX)|<= Retrieves User X's profile=>|
         |               |                               |

   (A-EX)  Device A discovers, enrolls and obtains notification related
      to user X's profile.
   (A-RX)  Device A retrieves user X's profile.
   (B-EX)  Device B discovers, enrolls and obtains notification related
      to user X's profile.
   (B-RX)  Device B retrieves user X's profile.
   (HPut)  Changes affected by the user via the user interface are
      uploaded to the HTTP Server.
      *  Note: The UI itself can act as a device and subscribe to user
         X's profile.  This is not the case in the example shown.
   (HRes)  Changes are accepted by the HTTP server.
   (A-NT)  PDS transmits a NOTIFY message to device A indicating the
      changed profile.  A sample message is shown below:
         Note: Some of the fields (e.g., Via) are continued on a
         separate line due to format constraints of this document.

   NOTIFY sip:userX@ SIP/2.0
   Event: ua-profile;effective-by=3600
   Call-ID: 3573853342923422@
   CSeq: 322 NOTIFY
   Via: SIP/2.0/UDP;
   MIME-Version: 1.0
   Content-Type: message/external-body; access-type="URL";
                 expiration="Mon, 01 Jan 2010 09:00:00 UTC";

   (A-RS)  Device A accepts the NOTIFY and sends a 200 OK
   (B-NT)  PDS transmits a NOTIFY message to device B indicating the
      changed profile.  A sample message is shown below:
         Note: Some of the fields (e.g., Via) are continued on a
         separate line due to format constraints of this document.

   NOTIFY sip:userX@ SIP/2.0
   Event: ua-profile;effective-by=3600
   Call-ID: 3573853342923422@
   CSeq: 322 NOTIFY
   Via: SIP/2.0/UDP;
   MIME-Version: 1.0
   Content-Type: message/external-body; access-type="URL";
                 expiration="Mon, 01 Jan 2010 09:00:00 UTC";

   (B-RS)  Device B accepts the NOTIFY and sends a 200 OK
   (A-RX)  Device A retrieves the updated profile pertaining to user X
   (B-RX)  Device B retrieves the updated profile pertaining to user X

8.  IANA Considerations

   There are two IANA considerations associated with this document, SIP
   Event Package and SIP configuration profile types.  These are
   outlined in the following sub-sections.

8.1.  SIP Event Package

   This specification registers a new event package as defined in
   [RFC3265].  The following information required for this registration:

      Package Name: ua-profile
      Package or Template-Package: This is a package
      Published Document: RFC XXXX (Note to RFC Editor: Please fill in
      XXXX with the RFC number of this specification)
      Persons to Contact: Daniel Petrie dan.ietf AT SIPez DOT com,
      New event header parameters: profile-type, vendor, model, version,
      effective-by (the profile-type parameter has predefined values.
      The new event header parameters do not)
   The following table illustrates the additions to the IANA SIP Header
   Field Parameters and Parameter Values: (Note to RFC Editor: Please
   fill in XXXX with the RFC number of this specification)

   Header Field                  Parameter Name     Values     Reference
   ----------------------------  ---------------   ---------   ---------
   Event                         profile-type      Yes         [RFCXXXX]
   Event                         vendor            No          [RFCXXXX]
   Event                         model             No          [RFCXXXX]
   Event                         version           No          [RFCXXXX]
   Event                         effective-by      No          [RFCXXXX]

8.2.  Registry of SIP configuration profile types

   This document requests IANA to register new SIP configuration profile
   types at under "SIP
   Configuration Profile Types".

   SIP configuration profile types allocations fall under the category
   "Specification Required", as explained in "Guidelines for Writing an
   IANA Considerations Section in RFCs" ([RFC2434]). ([RFC5226]).

   Registrations with the IANA MUST include a the profile type, and a
   published document which describes its purpose and usage.

   As this document specifies three SIP configuration profile types, the
   initial IANA registration will contain the information shown in the
   table below.  It also demonstrates the type of information maintained
   by the IANA.

         Profile Type                          Reference
         --------------                         ---------
         local-network                          [RFCXXXX]
         device                                 [RFCXXXX]
         user                                   [RFCXXXX]

         Daniel Petrie dan.ietf AT SIPez DOT com

   Note to RFC editor: Please replace RFCXXXX with the RFC number
   assigned to this document.

9.  Security Considerations

   The framework specified in this documents specifies profile delivery
   stages, an event package and three profile types to enable profile
   delivery.  The profile delivery stages are: enrollment, content
   retrieval, and change notification.  The event package helps with
   enrollment and change notifications.  Each profile type allows for
   profile retrieval from a PDS belonging to a specific provider.

   Enrollment allows a device to request, and if successful, enroll with
   a PDS to obtain profile data.  To transmit the request the device
   relies on configured, cached or discovered data.  Such data includes
   provider domain names, identities, and credentials.  The device
   either uses configured outbound proxies or discovers the next-hop
   entity using [RFC3263] that can result in a SIP proxy or the PDS.  It
   then transmits the request.  A SIP Proxy receving the request uses
   the Request-URI and event header contents to route it to a PDS (via
   other SIP proxies, if required).

   When a PDS receives the enrollment request, it can either challenge
   any contained identity or admit the enrollment.  Authorization rules
   then decide if the enrollment gets accepted.  If accepted, the PDS
   sends an initial notification that contains either the profile data,
   or content indirection information.  The profile data can contain
   generic profile data (common across multiple devices) or information
   specific to an entity (such as the device or a user).  If specific to
   an entity, it may contain sensitive information such as credentials.
   Compromise of sensitive data can lead to threats such as
   impersonation attacks (establishing rogue sessions), theft of service
   (if services are obtainable), and zombie attacks.  It is important
   for the device to ensure the authenticity of the PNC and the PCC
   since impersonation of the SIP service provider can lead to Denial of
   Service and Man-in-the-Middle attacks.

   Profile content retrieval allows a device to retrieve profile data
   via content indirection from a PCC.  This communication is
   accomplished using one of many profile delivery protocols or
   frameworks, such as HTTP or HTTPS as specified in this document.
   However, since the profile data returned is subject to the same
   considerations as that sent via profile notification, similar threats
   exist.  For example, denial of service attacks (rogue devices bombard
   the PCC with requests for a specific profile) and attempts to modify
   erroneous data onto the PCC (since the location and format may be
   known).  Thus, for the delivery of any sensitive profile data,
   authentication of the entity requesting profile data is required.  It
   is also important for the requesting entity to authenticate the
   profile source via content indirection, and ensure that the sensitive
   profile data is protected via message integrity.  For sensitive data
   that should not be subject to snooping, privacy is also required.

   The following sub-sections highlight the security considerations that
   are specific to each profile type.

9.1.  Local-network profile

   A local network may or may not (e.g., home router) support local-
   network profiles as specified in this framework.  Even if supported,
   the PDS may only be configured with a generic local-network profile
   that is provided to every device that requests the local-network
   profile.  Such a PDS may not implement any authentication
   requirements or TLS.

   Alternatively, certain deployments may require the entities - device
   and the PDS - to authenticate each other prior to successful profile
   enrollment.  Such networks may pre-configure user identities to the
   devices and allow user-specific local-network profiles.  In such
   networks the PDS will support digest, and the devices are configured
   with user identities and credentials as specified in Section 5.3.1.
   If sensitive profile data is being transmitted, the user identity is
   a SIPS URI that results in TLS with the next-hop (which is
   authenticated), and digest authentication is used by the PDS and the

   This framework supports both use cases and any variations in-between.
   However, devices obtaining local-network profiles from an
   unauthenticated PDS are cautioned against potential Man-in-the-Middle
   or PDS impersonation attacks.  This framework requires that a device
   reject sensitive data, such as credentials, from unauthenticated
   local-network sources.  It also prohibits devices from responding to
   authentication challenges in the absence TLS on all hops as a result
   of using a SIPS URI.  Responding to unauthenticated challenges allows
   for dictionary attacks that can reveal weak passwords.  The only
   exception to accepting such sensitive data without authentication of
   the PDS is in the case of bootstrapping (see Section 5.3.1).  In the
   case of bootstrapping, the methods employed need to be aware of
   potential security threats such as impersonation.

   The use of SIP Identity is useful for the device to validate
   notifications in the absence of a secure channel such as TLS when a
   SIPS URI is used.  In such cases the device can validate the SIP
   Identity header to verify the source of the profile notification, and
   the source of the profile data when content indirection is not used.
   However, the presence of the header does not guarantee the validity
   of the data.  It verifies the source and confirms data integrity, but
   the data obtained from an undesired source may still be invalid,
   e.g., invalid outbound proxy information, resulting in Denial of
   Service.  Thus, devices requesting the local-network profile from
   unknown networks need to be prepared to discard information that
   prevent retrieval of other, required, profiles.

9.2.  Device profile

   Device profiles deal with device-specific configuration.  They may be
   provided to unknown devices that are attempting to obtaining profiles
   for purposes such as trials, self-subscription (not to be confused
   with [RFC3265]) and emergency services ([I-D.ietf-ecrit-phonebcp]).

   This framework allows for the device profile to be used for
   bootstrapping a device.  Such bootstrapping profile data may contain
   enough information to connect to a Provider.  For example, it may
   enable the device to communicate with a device provider, allowing for
   trial or self-subscription services via visual or audio interfaces
   (e.g., interactive voice response), or customer service
   representatives.  The profile data may also allow the device a choice
   of device providers and allow the end-user to choose one.  The
   profile data may also contain identities and credentials (temporary
   or long-term) that can be used to obtain further profile data from
   the network.  This framework recommends the use of the SIP Identity
   header by the PDS.  However, to be able to validate the SIP Identity
   header, the device needs to be pre-configured with the knowledge of
   allowable domains or certificates for validation (e.g., using PKI).
   If not, the device can still guarantee header and body integrity if
   the profile data contains the domain certificate (but the data can
   still be invalid or malicious).  In such cases, devices supporting
   user interfaces may obtain confirmation from the user trying to
   bootstrap the device (confirming header and body integrity).
   However, when the SIP Identity header is not present, or the device
   is not capable of validating it, the bootstrapping data is
   unauthenticated and obtained without any integrity protection.  Such
   bootstrapping data, however, may contain only temporary credentials
   (SIPS URI and digest credentials) that can be used to reconnect to
   the network to ensure message integrity and privacy prior to
   obtaining long-term credentials.  It is to be noted that such devices
   are at the mercy of the network they request the device profile from.
   If they are initialized in a rogue network, or get hijacked by a
   rogue PDS, the end-user may be left without desired device operation
   or, worse, unwanted operation.  To mitigate such factors the device
   provider may communicate temporary credentials (e.g., passwords that
   can be entered via an interface) or permanent credentials (e.g., a
   USB device) to the end-user for connectivity.  If such methods are
   used, those credentials MUST be quickly replaced by large-entropy
   credentials, to minimize the impact of dictionary attacks.  Future
   enhancements to this framework may specify device capabilities that
   allow for authentication without any provider specific configuration
   (e.g., X.509 certificates using PKI can allow for authentication by
   any provider with access to the CA certificate).  Alternatively, the
   device may be pre-configured with with credentials for use with
   content indirection mechanisms.  In such circumstances a PDS can use
   secure content indirection mechanism, such as HTTPS, to provide the
   bootstrapping data.

   Once a device is associated with a device provider the device profile
   is vital to device operation.  This is because the device profile can
   contain important operational information such as users that are to
   be allowed access (white-list or black-list), user credentials (if
   required) and other sensitive information.  Thus, it is necessary to
   ensure that any device profile containing sensitive information is
   obtained via an authenticated source, with integrity protection, and
   delivered to an authenticated device.  For sensitive information such
   as credentials, privacy is also required.  The framework requires
   that devices obtain sensitive information only from authenticated
   entities except while it is being bootstrapped.  In cases where
   privacy needs to be mandated for notifications, the device provider
   can configure the device with a SIPS URI, to be used as the
   subscription URI, during profile enrollment.  The framework also
   requires a PDS presenting sensitive profile data to use digest
   authentication.  This ensures that the data is delivered to an
   authenticated entity.  Authentication of profile retrieval via
   content indirection for sensitive profiles is via HTTPS utilizing
   HTTP digest.

9.3.  User profile

   Devices can only request user profiles for users that are known by a
   SIP service provider.  PDSs are required to reject user profile
   enrollment requests for any users that are unknown in the network.
   For known user AoRs that are allowed to retrieve profiles, the
   security considerations are similar to that of the device profile
   (except for bootstrapping).

10.  Acknowledgements

   The author appreciates all those who contributed and commented on the
   many iterations of this document.  Detailed comments were provided by
   the following individuals: Jonathan Rosenberg from Cisco, Henning
   Schulzrinne from Columbia University, Cullen Jennings from Cisco,
   Rohan Mahy from Plantronics, Rich Schaaf from Pingtel, Volker Hilt
   from Bell Labs, Adam Roach of Estacado Systems, Hisham Khartabil from
   Telio, Henry Sinnreich from MCI, Martin Dolly from AT&T Labs, John
   Elwell from Siemens, Elliot Eichen and Robert Liao from Verizon, Dale
   Worley from Pingtel, Francois Audet from Nortel, Roni Even from
   Polycom, Jason Fischl from Counterpath, Josh Littlefield from Cisco,
   Nhut Nguyen from Samsung.

   The final revisions of this document were a product of design team
   discussions.  The editor wishes to extend special appreciation to the
   following design team members for their numerous reviews and specific
   contributions to various sections: Josh Littlefield from Cisco
   (Overview, Section 6), Peter Blatherwick from Mitel (Section 6),
   Cullen Jennings (Security), Sam Ganesan (Section 6) and Mary Barnes
   (layout, Section 6).

   The following design team members are thanked for numerous reviews
   and general contributions: Martin Dolly from AT&T Labs, Jason Fischl
   from Counterpath, Alvin Jiang of Engin and Francois Audet from

   The following SIPPING WG members are thanked for numerous reviews,
   comments and recommendations: John Elwell from Siemens, Donald Lukacs
   from Telcordia, Roni Even from Polycom, David Robbins from Verizon,
   Shida Schubert from NTT Advanced Technology Corporation, and Eugene
   Nechamkin from Broadcom.  The editor would also like to extend a
   special thanks to the comments and recommendations provided by the
   SIPPING WG, specifically Keith Drage from Lucent (restructuring
   proposal) and John Elwell from Siemens (numerous reviews and

   Additionally, appreciation is also due to Peter Koch for expert DNS

   And finally, sincere appreciation is extended to the chairs (Mary
   Barnes from Nortel and Gonzalo Camarillo from Ericsson) and the Area
   Directors (Cullen Jennings from Cisco and Jon Peterson from Neustar)
   for facilitating discussions, reviews and contributions.

11.  References

11.1.  Normative References

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

   [RFC2434]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 2434,
              October 1998.

   [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.

   [RFC3319]  Schulzrinne, H. and B. Volz, "Dynamic Host Configuration
              Protocol (DHCPv6) Options for Session Initiation Protocol
              (SIP) Servers", RFC 3319, July 2003.

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

   [RFC4122]  Leach, P., Mealling, M., and R. Salz, "A Universally
              Unique IDentifier (UUID) URN Namespace", RFC 4122,
              July 2005.

   [RFC4346]  Dierks, T. and E. Rescorla, "The Transport Layer Security
              (TLS) Protocol Version 1.1", RFC 4346, April 2006.

   [RFC4474]  Peterson, J. and C. Jennings, "Enhancements for
              Authenticated Identity Management in the Session
              Initiation Protocol (SIP)", RFC 4474, August 2006.

   [RFC4483]  Burger, E., "A Mechanism for Content Indirection in
              Session Initiation Protocol (SIP) Messages", RFC 4483,
              May 2006.

   [RFC4704]  Volz, B., "The Dynamic Host Configuration Protocol for
              IPv6 (DHCPv6) Client Fully Qualified Domain Name (FQDN)
              Option", RFC 4704, October 2006.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              May 2008.

   [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
              (TLS) Protocol Version 1.2", RFC 5246, August 2008.

11.2.  Informative References

              Rosen, B. and J. Polk, "Best Current Practice for
              Communications Services in support of Emergency  Calling",
              draft-ietf-ecrit-phonebcp-13 (work in progress),
              September 2007.
              July 2009.

              Jennings, C. and R. Mahy, C., "Managing Client Initiated Connections in
              the Session Initiation Protocol  (SIP)",
              draft-ietf-sip-outbound-20 (work in progress),
              November 2007. June 2009.

   [RFC0959]  Postel, J. and J. Reynolds, "File Transfer Protocol",
              STD 9, RFC 959, October 1985.

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

   [RFC4510]  Zeilenga, K., "Lightweight Directory Access Protocol
              (LDAP): Technical Specification Road Map", RFC 4510,
              June 2006.

   [RFC4825]  Rosenberg, J., "The Extensible Markup Language (XML)
              Configuration Access Protocol (XCAP)", RFC 4825, May 2007.

Authors' Addresses

   Daniel Petrie
   SIPez LLC.
   34 Robbins Rd
   Arlington, MA  02476

   Email: dan.ietf AT SIPez DOT com

   Sumanth Channabasappa (Editor)
   858 Coal Creek Circle
   Louisville, Co  80027


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