    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.

                                   --------------
                                 / 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.

          --------
        /   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

                         - Prepare and transmit Enrollment Request

                         - Await Enrollment Acceptance and initial NOTIFY

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

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

                      End Loop: Loop 3

                 End Loop: Loop 2

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

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

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

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

                 - increment i;

                 - 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).

                   -----           -----
                  |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]