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rfc:rfc6080

Internet Engineering Task Force (IETF) D. Petrie Request for Comments: 6080 SIPez LLC Category: Standards Track S. Channabasappa, Ed. ISSN: 2070-1721 CableLabs

                                                            March 2011

A Framework for Session Initiation Protocol User Agent Profile Delivery

Abstract

 This document specifies a framework to enable configuration of
 Session Initiation Protocol (SIP) user agents (UAs) 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.

Status of This Memo

 This is an Internet Standards Track document.
 This document is a product of the Internet Engineering Task Force
 (IETF).  It represents the consensus of the IETF community.  It has
 received public review and has been approved for publication by the
 Internet Engineering Steering Group (IESG).  Further information on
 Internet Standards is available in Section 2 of RFC 5741.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at
 http://www.rfc-editor.org/info/rfc6080.

Petrie & Channabasappa Standards Track [Page 1] RFC 6080 SIP Configuration Framework March 2011

Copyright Notice

 Copyright (c) 2011 IETF Trust and the persons identified as the
 document authors.  All rights reserved.
 This document is subject to BCP 78 and the IETF Trust's Legal
 Provisions Relating to IETF Documents
 (http://trustee.ietf.org/license-info) in effect on the date of
 publication of this document.  Please review these documents
 carefully, as they describe your rights and restrictions with respect
 to this document.  Code Components extracted from this document must
 include Simplified BSD License text as described in Section 4.e of
 the Trust Legal Provisions and are provided without warranty as
 described in the Simplified BSD License.
 This document may contain material from IETF Documents or IETF
 Contributions published or made publicly available before November
 10, 2008.  The person(s) controlling the copyright in some of this
 material may not have granted the IETF Trust the right to allow
 modifications of such material outside the IETF Standards Process.
 Without obtaining an adequate license from the person(s) controlling
 the copyright in such materials, this document may not be modified
 outside the IETF Standards Process, and derivative works of it may
 not be created outside the IETF Standards Process, except to format
 it for publication as an RFC or to translate it into languages other
 than English.

Petrie & Channabasappa Standards Track [Page 2] RFC 6080 SIP Configuration Framework March 2011

Table of Contents

 1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
 2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  4
 3.  Overview . . . . . . . . . . . . . . . . . . . . . . . . . . .  5
   3.1.  Reference Model  . . . . . . . . . . . . . . . . . . . . .  6
   3.2.  Motivation . . . . . . . . . . . . . . . . . . . . . . . .  7
   3.3.  Profile Types  . . . . . . . . . . . . . . . . . . . . . .  9
   3.4.  Profile Delivery Stages  . . . . . . . . . . . . . . . . .  9
   3.5.  Supported Device Types . . . . . . . . . . . . . . . . . . 10
 4.  Use Cases  . . . . . . . . . . . . . . . . . . . . . . . . . . 10
   4.1.  Simple Deployment Scenario . . . . . . . . . . . . . . . . 10
   4.2.  Devices Supporting Multiple Users from Different
         Service Providers  . . . . . . . . . . . . . . . . . . . . 12
 5.  Profile Delivery Framework . . . . . . . . . . . . . . . . . . 14
   5.1.  Profile Delivery Stages  . . . . . . . . . . . . . . . . . 14
   5.2.  Securing Profile Delivery  . . . . . . . . . . . . . . . . 22
   5.3.  Additional Considerations  . . . . . . . . . . . . . . . . 24
   5.4.  Support for NATs . . . . . . . . . . . . . . . . . . . . . 33
 6.  Event Package Definition . . . . . . . . . . . . . . . . . . . 33
   6.1.  Event Package Name . . . . . . . . . . . . . . . . . . . . 33
   6.2.  Event Package Parameters . . . . . . . . . . . . . . . . . 33
   6.3.  SUBSCRIBE Bodies . . . . . . . . . . . . . . . . . . . . . 36
   6.4.  Subscription Duration  . . . . . . . . . . . . . . . . . . 37
   6.5.  NOTIFY Bodies  . . . . . . . . . . . . . . . . . . . . . . 37
   6.6.  Notifier Processing of SUBSCRIBE Requests  . . . . . . . . 37
   6.7.  Notifier Generation of NOTIFY Requests . . . . . . . . . . 38
   6.8.  Subscriber Processing of NOTIFY Requests . . . . . . . . . 38
   6.9.  Handling of Forked Requests  . . . . . . . . . . . . . . . 39
   6.10. Rate of Notifications  . . . . . . . . . . . . . . . . . . 39
   6.11. State Agents . . . . . . . . . . . . . . . . . . . . . . . 39
 7.  Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
   7.1.  Example 1: Device Requesting Profile . . . . . . . . . . . 39
   7.2.  Example 2: Device Obtaining Change Notification  . . . . . 42
 8.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 46
   8.1.  SIP Event Package  . . . . . . . . . . . . . . . . . . . . 46
   8.2.  Registry of SIP Configuration Profile Types  . . . . . . . 46
 9.  Security Considerations  . . . . . . . . . . . . . . . . . . . 47
   9.1.  Local-Network Profile  . . . . . . . . . . . . . . . . . . 48
   9.2.  Device Profile . . . . . . . . . . . . . . . . . . . . . . 49
   9.3.  User Profile . . . . . . . . . . . . . . . . . . . . . . . 50
 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 51
 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 52
   11.1. Normative References . . . . . . . . . . . . . . . . . . . 52
   11.2. Informative References . . . . . . . . . . . . . . . . . . 53

Petrie & Channabasappa Standards Track [Page 3] RFC 6080 SIP Configuration Framework March 2011

1. Introduction

 SIP user agents require configuration data to function properly.
 Examples include information specific to local networks, devices, and
 users.  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
 intervention.
 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 that 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.  The normative requirements
 are contained in Section 5 (framework operations) and Section 6 (the
 event package definition).  The rest of the document provides
 introductory and supporting explanations.  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 7 follows with illustrative examples of the framework in use.

2. Terminology

 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
 document are to be interpreted as described in RFC 2119 [RFC2119].
 This document also reuses the SIP terminology defined in [RFC3261]
 and [RFC3265], and it specifies the usage of the following terms.
 Device:  software or hardware entity containing one or more SIP user
    agents.  It may also contain applications 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 or public enterprises.

Petrie & Channabasappa Standards Track [Page 4] RFC 6080 SIP Configuration Framework March 2011

 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.
 Bootstrapping:  Bootstrapping is the process by which a new (or
    factory reset) device, with no configuration or minimal "factory"
    pre-configuration, enrolls with the PDS.  The device may use a
    temporary identity and credentials to authenticate itself to
    enroll and receive profiles, which may provide more permanent
    identities and credentials for future enrollments.

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 that 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

Petrie & Channabasappa Standards Track [Page 5] RFC 6080 SIP Configuration Framework March 2011

 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 User Agent Server (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.

Petrie & Channabasappa Standards Track [Page 6] RFC 6080 SIP Configuration Framework March 2011

 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
 deployments.
 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.
  1. ————-

/ Local Network, \

                          | Device & Service |
                           \    Provider    /
                            ----------------
                                   |
                                   |
                                --------
                               | Device |
                                --------
                                   |
                                   |
                                 ----
                                |User|
                                 ----
                   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

Petrie & Channabasappa Standards Track [Page 7] RFC 6080 SIP Configuration Framework March 2011

 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.
  1. ——-

/ 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 which to connect 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

Petrie & Channabasappa Standards Track [Page 8] RFC 6080 SIP Configuration Framework March 2011

 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 subsections to follow.

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 to which it is subscribed.  It is provided by
    the SIP service provider.
 Additional profile types may also be specified by future work within
    the IETF.  The data models associated with each profile type are
    out of scope for this document.

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.

Petrie & Channabasappa Standards Track [Page 9] RFC 6080 SIP Configuration Framework March 2011

 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
    information.

3.5. Supported 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).  The framework
 is extensible for use with such device types.  However, it is to be
 noted that some of these other device types (e.g., network elements)
 may also be configurable using other mechanisms.  The use of this
 framework in conjunction with other mechanisms (specified outside of
 this document), is out of scope.

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 Sections 5 and 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

Petrie & Channabasappa Standards Track [Page 10] RFC 6080 SIP Configuration Framework March 2011

 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 includes device
 start-up 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
 Notification.
                                       +----------------------+
  +--------+                           |  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 an 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.

Petrie & Channabasappa Standards Track [Page 11] RFC 6080 SIP Configuration Framework March 2011

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

Petrie & Channabasappa Standards Track [Page 12] RFC 6080 SIP Configuration Framework March 2011

   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>>
       |
                    .
                    .
                    .
       |   Profile Enrollment  |      |          |           |
   (D) |<= user profile (A) => |<====>|          |           |
       |                       |      |          |           |
       |
       |   <<Profile content retrieval>>
                            .
           [[User A obtains services]]
                    .
                    .
                    .
       |
       |            Profile Enrollment           |           |
   (E) |<=========== user profile (B) ==========>|<=========>|
       |                                         |           |
       |   <<Profile content retrieval>>
       |
           [[User B obtains services]]
                         Figure 5: Use Case 2

Petrie & Channabasappa Standards Track [Page 13] RFC 6080 SIP Configuration Framework March 2011

 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 [RFC5626].

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 subsections
 provide the requirements associated with each stage.

Petrie & Channabasappa Standards Track [Page 14] RFC 6080 SIP Configuration Framework March 2011

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.
 PDSs and devices MUST implement all of the three profile types.  A
 device that has not been configured otherwise SHOULD try to obtain
 all the three profile types, in the order specified by this
 framework.  The exceptions are bootstrapping when it SHOULD request
 the device profile type (see Section 5.3.1) or when it has been
 explicitly configured with a different order via mechanisms such as
 previously retrieved profile data or pre-configuration or manual
 configuration.
 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 and device or user
    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
    apply.
  • 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.

Petrie & Channabasappa Standards Track [Page 15] RFC 6080 SIP Configuration Framework March 2011

  • 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
       'example.net', it cannot present a user Address of Record (AoR)
       associated with the local domain 'example.com'.
  • 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 SHOULD NOT 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
    response (e.g., recognition of a denial-of-service (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 Sections 6.6 and 5.2 for more information on subscription
    request handling and security requirements, respectively.

Petrie & Channabasappa Standards Track [Page 16] RFC 6080 SIP Configuration Framework March 2011

 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
    subscription.

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

Petrie & Channabasappa Standards Track [Page 17] RFC 6080 SIP Configuration Framework March 2011

 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 (the
 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.

5.1.4.1. 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.

Petrie & Channabasappa Standards Track [Page 18] RFC 6080 SIP Configuration Framework March 2011

 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) the device
    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 [RFC5626].  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: airport.example.net, then the local-network
 profile SUBSCRIBE Request-URI would look like:
 sip:_sipuaconfig.airport.example.net
 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
 servers.
 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.

5.1.4.2. 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

Petrie & Channabasappa Standards Track [Page 19] RFC 6080 SIP Configuration Framework March 2011

 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 [RFC5626].  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".

Petrie & Channabasappa Standards Track [Page 20] RFC 6080 SIP Configuration Framework March 2011

 If the device needs to create a Subscription URI and needs to use its
 device identifier, it MUST use the UUID-based (Universally Unique
 Identifier) URN representation as specified in [RFC4122].  The
 following requirements apply:
 o  When the device has a non-alterable Media Access Control (MAC)
    address, it SHOULD use the 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 use
    the same approach as defining a user agent instance ID in
    [RFC5626].
 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:
       urn:uuid:f81d4fae-7ced-11d0-a765-00a0c91e6bf6@example.com
       would be escaped to look as follows in a URI:
       sip:urn%3auuid%3af81d4fae-7ced-11d0-a765-00a0c91e6bf6@
       example.com
       The ABNF ([RFC5234]) for the UUID representation is provided in
       [RFC4122].

5.1.4.3. 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:

Petrie & Channabasappa Standards Track [Page 21] RFC 6080 SIP Configuration Framework March 2011

 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, data integrity and data confidentiality.
 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
 data 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, data confidentiality 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.
 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 5.3.3), devices
 and PDSs MUST support digest authentication (over Transport Layer
 Security (TLS)) as specified in [RFC3261].  Future enhancements may

Petrie & Channabasappa Standards Track [Page 22] RFC 6080 SIP Configuration Framework March 2011

 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 data integrity.  This can be accomplished by configuring the
 device with, or by ensuring that the discovery process during profile
 enrollment provides, a Session Initiation Protocol Secure (SIPS) URI
 resulting in TLS establishment ([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 those used for SIP registration (see
 Section 5.3.1).  In addition, while [RFC3261] considers MD5 to be a
 reasonable choice to compute the hash, and this may have been true
 when [RFC3261] was published, implementers are recommended to use
 stronger alternatives such as SHA-256.  Refer to [FIPS-180-3] and
 [RFC4634] for more information about SHA-256.
 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.,
 certification authority (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 Public Key

Petrie & Channabasappa Standards Track [Page 23] RFC 6080 SIP Configuration Framework March 2011

 Infrastructure (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
 protocols.
 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 data integrity and
 data confidentiality.

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 data
 confidentiality , 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 authenticated.

5.3. Additional Considerations

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

Petrie & Channabasappa Standards Track [Page 24] RFC 6080 SIP Configuration Framework March 2011

5.3.1. Bootstrapping Identities and Credentials

 When requesting a profile, the profile delivery server will likely
 require the device to provide an identity (i.e., a user AoR) and
 associated credentials for authentication.  During this process
 (e.g., digest authentication), the PDS is also required to present
 its knowledge of the credentials to ensure mutual authentication (see
 Section 5.2.1).  For mutual authentication with the PDS, the device
 needs to be provided with the necessary identities and credentials
 (e.g., username/password, certificates).  This is done via
 bootstrapping.  For a discussion around the security considerations
 related to bootstrapping, please see Section 9.2.
 Bootstrapping a device with the required identities and credentials
 can be accomplished in one of the following ways:
 Pre-configuration
    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 Subscriber Identity Module (SIM) cards or
    Universal Serial Bus (USB) drives.
 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
    device:
  • 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.

Petrie & Channabasappa Standards Track [Page 25] RFC 6080 SIP Configuration Framework March 2011

  • Content indirection information to a PCC that can provide

identities and credentials. As an example, consider a device

       that has an 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 5.3.3 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
       reasons.
 For interoperability purposes, this framework requires PDSs and
 devices to support the last option (above), which is to use this
 framework.  Specifically, the option of providing identities and
 credentials via the profile data MUST be supported.
 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.

Petrie & Channabasappa Standards Track [Page 26] RFC 6080 SIP Configuration Framework March 2011

                              +------------+
                              | Initialize |
                              +-----+------+
                                    |
                                    |
                                    V
                             +-------------+
                             |   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

Petrie & Channabasappa Standards Track [Page 27] RFC 6080 SIP Configuration Framework March 2011

 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 back-off and retry mechanisms as indicated in Figure 7.

Petrie & Channabasappa Standards Track [Page 28] RFC 6080 SIP Configuration Framework March 2011

   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
  1. Prepare and transmit Enrollment Request
  1. 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
  1. Delay for 2^i*(64*T1); – this is exponential back-off
  1. increment i;
  1. If i>8, reset i=8;
     End loop: Loop 1
 End Function()
          Figure 7: Profile Enrollment Attempt (Pseudo-Code)

Petrie & Channabasappa Standards Track [Page 29] RFC 6080 SIP Configuration Framework March 2011

 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
 that 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 with which they are associated.
 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
 definitions.
 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
 feature.

5.3.3. 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 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.

Petrie & Channabasappa Standards Track [Page 30] RFC 6080 SIP Configuration Framework March 2011

    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 applications.
 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 disclosed to
    unauthorized parties.  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.

5.3.4. 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).  Thus, Profile Data Frameworks 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 XML
 Configuration Access Protocol (XCAP) ([RFC4825]).

Petrie & Channabasappa Standards Track [Page 31] RFC 6080 SIP Configuration Framework March 2011

5.3.5. 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
 document.

5.3.6. Deployment Considerations

 The framework defined in this document was designed to address
 various deployment considerations, some of which are highlighted
 below.
 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 to which a user subscribes (telephony service, instant
    messaging, etc.); this framework does not specify explicit
    behavior in such a scenario, but it does not prohibit its usage
    either.
 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.

Petrie & Channabasappa Standards Track [Page 32] RFC 6080 SIP Configuration Framework March 2011

5.4. Support for NATs

 PDSs that support devices behind NATs, and devices that can be behind
 NATs can use procedures specified in [RFC5626].  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 [RFC5626], within
 the SIP SUBSCRIBE for profile enrollment.

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 subsections 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
 header:
    "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
 subsections.

Petrie & Channabasappa Standards Track [Page 33] RFC 6080 SIP Configuration Framework March 2011

6.2.1. "profile-type" Parameter

 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 the "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
 notifications.
 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.

Petrie & Channabasappa Standards Track [Page 34] RFC 6080 SIP Configuration Framework March 2011

6.2.2. "vendor", "model", and "version" Parameters

 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., example.com) as
 the value of the "vendor" parameter so that it is known to be unique,
 unless there is a good reason not to.  Examples of exceptions
 include: if the vendor does not have an assigned DNS domain name, if
 they are using a different vendor's implementation, etc.  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.  For example, 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 that may occur in SUBSCRIBE
 requests.  These examples are not intended to be complete SUBSCRIBE
 requests.

Petrie & Channabasappa Standards Track [Page 35] RFC 6080 SIP Configuration Framework March 2011

 Event: ua-profile;profile-type=device;
        vendor="vendor.example.com";model="Z100";version="1.2.3"
 Event: ua-profile;profile-type=user;
        vendor="premier.example.com";model="trs8000";version="5.5"
 The following are example Event headers that 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 - MUST be provided
 s - SHOULD be provided
 o - OPTIONAL to be provided
 Non-specified means that the parameter has no meaning and should be
 ignored.
 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 that may specify a use for the
 SUBSCRIBE request body.

Petrie & Channabasappa Standards Track [Page 36] RFC 6080 SIP Configuration Framework March 2011

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], Lightweight Directory Access Protocol (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

Petrie & Channabasappa Standards Track [Page 37] RFC 6080 SIP Configuration Framework March 2011

 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

Petrie & Channabasappa Standards Track [Page 38] RFC 6080 SIP Configuration Framework March 2011

 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
 example).
 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
    network).

Petrie & Channabasappa Standards Track [Page 39] RFC 6080 SIP Configuration Framework March 2011

 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                   |
 (XReq)|---------------------------------------------->|
       |                                               |
       |                HTTP Response                  |
 (XRes)|<----------------------------------------------|
       |                                               |

Petrie & Channabasappa Standards Track [Page 40] RFC 6080 SIP Configuration Framework March 2011

 (SReq)
    the device transmits a request for the 'device' profile using the
    SIP SUBSCRIBE utilizing the event package specified in this
    framework.
  • 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
           @example.com  SIP/2.0
 Event: ua-profile;profile-type=device;vendor="vendor.example.net";
        model="Z100";version="1.2.3"
 From: anonymous@example.com;tag=1234
 To: sip:urn%3auuid%3a00000000-0000-1000-0000-00FF8D82EDCB@example.com
 Call-ID: 3573853342923422@192.0.2.44
 CSeq: 2131 SUBSCRIBE
 Contact: sip:urn%3auuid%3a00000000-0000-1000-0000-00FF8D82EDCB
    @192.168.1.44
    ;+sip.instance="<urn:uuid:00000000-0000-0000-0000-123456789AB0>"
    ;schemes="http,https"
 Via: SIP/2.0/TCP 192.0.2.41;
   branch=z9hG4bK6d6d35b6e2a203104d97211a3d18f57a
 Accept: message/external-body, application/x-z100-device-profile
 Content-Length: 0
 (SRes)  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).

 (NTFY)  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.

Petrie & Channabasappa Standards Track [Page 41] RFC 6080 SIP Configuration Framework March 2011

NOTIFY sip:urn%3auuid%3a00000000-0000-1000-0000-00FF8D82EDCB

      @192.168.1.44 SIP/2.0

Event: ua-profile;effective-by=3600 From: sip:urn%3auuid%3a00000000-0000-1000-0000-00FF8D82EDCB@example.com

     ;tag=abca

To: sip:urn%3auuid%3a00000000-0000-1000-0000-00FF8D82EDCB@example.com

   ;tag=1234

Call-ID: 3573853342923422@192.0.2.44 CSeq: 322 NOTIFY Via: SIP/2.0/UDP 192.0.2.3;

 branch=z9hG4bK1e3effada91dc37fd5a0c95cbf6767d0

MIME-Version: 1.0 Content-Type: message/external-body; access-type="URL";

             expiration="Mon, 01 Jan 2010 09:00:00 UTC";
             URL="http://example.com/z100-000000000000.html";
             size=9999;
             hash=10AB568E91245681AC1B

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

 (NRes)  Device accepts the NOTIFY message and responds with a 200 OK.
 (XReq)  once the necessary secure communications channel is
    established, the device sends an HTTP request to the HTTP server
    indicated in the NOTIFY.
 (XRes)  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
    profile.

Petrie & Channabasappa Standards Track [Page 42] RFC 6080 SIP Configuration Framework March 2011

 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,
    device).
  1. —- —–

|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 |      |
       |                                |------>|      |

Petrie & Channabasappa Standards Track [Page 43] RFC 6080 SIP Configuration Framework March 2011

       |                                               |
       |               |                | 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 Unique Identifier (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.

Petrie & Channabasappa Standards Track [Page 44] RFC 6080 SIP Configuration Framework March 2011

 NOTIFY sip:userX@192.0.2.44 SIP/2.0
 Event: ua-profile;effective-by=3600
 From: sip:userX@sip.example.net;tag=abcd
 To: sip:userX@sip.example.net.net;tag=1234
 Call-ID: 3573853342923422@192.0.2.44
 CSeq: 322 NOTIFY
 Via: SIP/2.0/UDP 192.0.2.3;
   branch=z9hG4bK1e3effada91dc37fd5a0c95cbf6767d1
 MIME-Version: 1.0
 Content-Type: message/external-body; access-type="URL";
               expiration="Mon, 01 Jan 2010 09:00:00 UTC";
               URL="http://www.example.com/user-x-profile.html";
               size=9999;
               hash=123456789AAABBBCCCDD
 .
 .
 .
 (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@192.0.2.43 SIP/2.0
 Event: ua-profile;effective-by=3600
 From: sip:userX@sip.example.net;tag=abce
 To: sip:userX@sip.example.net.net;tag=1234
 Call-ID: 3573853342923422@192.0.2.43
 CSeq: 322 NOTIFY
 Via: SIP/2.0/UDP 192.0.2.3;
   branch=z9hG4bK1e3effada91dc37fd5a0c95cbf6767d2
 MIME-Version: 1.0
 Content-Type: message/external-body; access-type="URL";
               expiration="Mon, 01 Jan 2010 09:00:00 UTC";
               URL="http://www.example.com/user-x-profile.html";
               size=9999;
               hash=123456789AAABBBCCCDD
 .
 .
 .
 (B-RS)   Device B accepts the NOTIFY and sends a 200 OK.
 (A-RX)   Device A retrieves the updated profile pertaining to user X.

Petrie & Channabasappa Standards Track [Page 45] RFC 6080 SIP Configuration Framework March 2011

 (B-RX)   Device B retrieves the updated profile pertaining to user X.

8. IANA Considerations

 IANA has registered a SIP event package, event header parameters, and
 SIP configuration profile types as outlined in the following
 subsections.

8.1. SIP Event Package

 This specification registers a new event package as defined in
 [RFC3265].  The registration is as follows:
 Package Name:  ua-profile
 Package or Template-Package:  This is a package
 Published Document:  RFC 6080
 Persons to Contact:  Daniel Petrie <dan.ietf@SIPez.com>,
    Sumanth Channabasappa <sumanth@cablelabs.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" registry:
                                                 Predefined
 Header Field                  Parameter Name    Values      Reference
 ----------------------------  ---------------   ----------  ---------
 Event                         profile-type      Yes         [RFC6080]
 Event                         vendor            No          [RFC6080]
 Event                         model             No          [RFC6080]
 Event                         version           No          [RFC6080]
 Event                         effective-by      No          [RFC6080]

8.2. Registry of SIP Configuration Profile Types

 IANA has registered new SIP configuration profile types at
 http://www.iana.org in the "SIP Configuration Profile Types"
 registry.
 The registration procedures are "Specification Required", as
 explained in "Guidelines for Writing an IANA Considerations Section
 in RFCs" ([RFC5226]).

Petrie & Channabasappa Standards Track [Page 46] RFC 6080 SIP Configuration Framework March 2011

 Registrations with the IANA MUST include the profile type, and a
 published document that describes its purpose and usage.
 As this document specifies three SIP configuration profile types, the
 initial IANA registration contains the information shown in the table
 below.
       Profile Type                          Reference
       --------------                         ---------
       local-network                          [RFC6080]
       device                                 [RFC6080]
       user                                   [RFC6080]

9. Security Considerations

 The framework specified in this document 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 receiving 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.
 Disclosure 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 DoS and
 man-in-the-middle (MITM) attacks.

Petrie & Channabasappa Standards Track [Page 47] RFC 6080 SIP Configuration Framework March 2011

 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, DoS 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 data integrity.  For sensitive data that should
 not be disclosed to unauthorized parties, data confidentiality is
 also required.
 The following subsections 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 authentication, 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 device.
 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 MITM 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 of TLS on all hops as a
 result of using a SIPS URI.  Responding to unauthenticated challenges

Petrie & Channabasappa Standards Track [Page 48] RFC 6080 SIP Configuration Framework March 2011

 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.
 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 DoS.  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 [PHONEBCP].
 This framework allows 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,

Petrie & Channabasappa Standards Track [Page 49] RFC 6080 SIP Configuration Framework March 2011

 may contain only temporary credentials (SIPS URI and digest
 credentials) that can be used to reconnect to the network to ensure
 data integrity and data confidentiality 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 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, data confidentiality is also required.  The framework
 requires that devices obtain sensitive information only from
 authenticated entities except while it is being bootstrapped.  In
 cases where data confidentiality 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.

Petrie & Channabasappa Standards Track [Page 50] RFC 6080 SIP Configuration Framework March 2011

 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, Henning Schulzrinne,
 Cullen Jennings, Rohan Mahy, Rich Schaaf, Volker Hilt, Adam Roach,
 Hisham Khartabil, Henry Sinnreich, Martin Dolly, John Elwell, Elliot
 Eichen, Robert Liao, Dale Worley, Francois Audet, Roni Even, Jason
 Fischl, Josh Littlefield, and Nhut Nguyen.
 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 (Overview,
 Section 6), Peter Blatherwick (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, Jason Fischl, Alvin Jiang,
 and Francois Audet.
 The following SIPPING WG members are thanked for numerous reviews,
 comments and recommendations: John Elwell, Donald Lukacs, Roni Even,
 David Robbins, Shida Schubert, and Eugene Nechamkin.  The editor
 would also like to extend a special thanks to the comments and
 recommendations provided by the SIPPING WG, specifically Keith Drage
 (restructuring proposal) and John Elwell (numerous reviews and
 recommendations).
 Additionally, appreciation is also due to Peter Koch for expert DNS
 advice.
 Finally, sincere appreciation is extended to the chairs (Mary Barnes
 and Gonzalo Camarillo); the past/current Area Directors (Cullen
 Jennings, Jon Peterson, and Robert Sparks) for facilitating
 discussions, reviews, and contributions; and, the expert reviewers
 from the IESG (Peter McCann, Catherine Meadows).

Petrie & Channabasappa Standards Track [Page 51] RFC 6080 SIP Configuration Framework March 2011

11. References

11.1. Normative References

 [FIPS-180-3]  National Institute of Standards and Technology (NIST),
               "Secure Hash Standard (SHS)", FIPS PUB 180-3,
               October 2008.
 [RFC2119]     Bradner, S., "Key words for use in RFCs to Indicate
               Requirement Levels", BCP 14, RFC 2119, March 1997.
 [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.

Petrie & Channabasappa Standards Track [Page 52] RFC 6080 SIP Configuration Framework March 2011

 [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.
 [RFC5234]     Crocker, D. and P. Overell, "Augmented BNF for Syntax
               Specifications: ABNF", STD 68, RFC 5234, January 2008.
 [RFC5246]     Dierks, T. and E. Rescorla, "The Transport Layer
               Security (TLS) Protocol Version 1.2", RFC 5246,
               August 2008.
 [RFC5626]     Jennings, C., Mahy, R., and F. Audet, "Managing Client-
               Initiated Connections in the Session Initiation
               Protocol (SIP)", RFC 5626, October 2009.

11.2. Informative References

 [PHONEBCP]    Rosen, B. and J. Polk, "Best Current Practice for
               Communications Services in support of Emergency
               Calling", Work in Progress, October 2010.
 [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.
 [RFC4634]     Eastlake, D. and T. Hansen, "US Secure Hash Algorithms
               (SHA and HMAC-SHA)", RFC 4634, July 2006.

Petrie & Channabasappa Standards Track [Page 53] RFC 6080 SIP Configuration Framework March 2011

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

Authors' Addresses

 Daniel Petrie
 SIPez LLC
 246A Park Ave
 Arlington, MA  02476
 USA
 EMail: dan.ietf@SIPez.com
 URI:   http://www.SIPez.com/
 Sumanth Channabasappa (editor)
 CableLabs
 858 Coal Creek Circle
 Louisville, CO  80027
 USA
 EMail: sumanth@cablelabs.com
 URI:   http://www.cablelabs.com/

Petrie & Channabasappa Standards Track [Page 54]

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