draft-ietf-sipping-config-framework-00.txt   draft-ietf-sipping-config-framework-01.txt 
D. Petrie SIPPING D. Petrie
Internet Draft Pingtel Corp. Internet-Draft Pingtel Corp.
draft-ietf-sipping-config-framework-00.txt Expires: April 21, 2004 October 22, 2003
Expires: Aug 2003 Feb 2003
A Framework for SIP User Agent Configuration A Framework for SIP User Agent Profile Delivery
draft-ietf-sipping-config-framework-01.txt
Status of this Memo Status of this Memo
This document is an Internet-Draft and is in full conformance This document is an Internet-Draft and is in full conformance with
with all provisions of Section 10 of RFC2026. all provisions of Section 10 of RFC2026.
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Abstract This Internet-Draft will expire on April 21, 2004.
This document defines the application of a set of protocols for
configuring a SIP user agent. The SIP user agent must discover how
and from where to retrieve its initial configuration and be notified
of changes and updates which impact its configuration. The
objective is to define a means for automatically configuring a user
agent such that it can be functional without user or administrative
intervention. The framework for discovery, delivery, notification
and updates of user agent configuration is defined here. This
framework is also intended to ease ongoing administration,
configuration and upgrading of large scale deployments of SIP user
agents. The contents and format of the configuration data to be
defined is outside the scope of this document.
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A Framework for SIP Feb. 2003
User Agent Configuration
Table of Contents
Status of this Memo................................................1
Abstract...........................................................1
1 Overview.......................................................3
2 Conventions used in this document..............................4
3 Changes from Previous Draft....................................4
3.1 Changes from draft-petrie-sipping-config-framework-00.txt....4
3.2 Changes from draft-petrie-sip-config-framework-01.txt........4
3.3 Changes from draft-petrie-sip-config-framework-00.txt........4
4 Discovery......................................................5
4.1 DHCP Option..................................................6
4.2 DNS..........................................................6
4.3 Multicast....................................................7
4.4 Manually Provisioned.........................................7
5 Enrollment and Change Notification.............................7
5.1 SUBSCRIBE....................................................8
5.1.1 Additional User Agent Field Parameters......................9
5.2 NOTIFY......................................................10
5.2.1 NOTIFY Body Content Format.................................11
6 Configuration Retrieval.......................................11
7 Configuration Upload..........................................11
8 Examples......................................................12
8.1 Example Message Flows.......................................12
8.2 Example Messages............................................14
9 Security Considerations.......................................17
10 Open Issues...................................................18
11 References....................................................19
12 Author's Address..............................................20
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A Framework for SIP Feb. 2003
User Agent Configuration
1 Overview
Today all SIP UA vendors use proprietary means of delivering
configuration to the UA. This configuration framework is intended
to enable a first phase migration to a standard means of configuring
SIP user agents. It is expected that UA vendors should be able to
use this configuration framework as a means of delivering their
existing proprietary configuration data profiles (i.e. using their
existing proprietary binary or text formats). This in itself is a
tremendous advantage in that a SIP environment can use a single
configuration server to deliver configuration data to UAs from
multiple vendors. Follow-on standardization activities can: 1)
define a standard format (e.g. XML or name-value pairs [8]) and 2)
specify the content (i.e. name the configuration parameters) of the
configuration data profiles.
This document defines a framework which allows SIP user agents (UA)
to automatically:
- discover a configuration server (Discovery)
- enroll with the configuration server (Enrollment)
- retrieve configuration data (Configuration Retrieval)
- receive notification of configuration changes (Change
Notification)
- upload configuration data changes back to the server
(Configuration Upload)
The content and format of the data is not defined in this document.
It will be defined in configuration data profile(s) in other
document(s). The goal of this framework is to satisfy the
requirements for configuration delivery defined in [10], [11] and
[16] explicitly excluding the requirements which pertain to
configuration data profile content and format.
Discovery is the process by which a UA SHOULD find the address and
port at which it SHOULD enroll with the configuration server. As
there is no single discovery mechanism which will work in all
network environments, a number of discovery mechanisms are defined
with a prescribed order in which the UA SHOULD try them until one
succeeds.
Enrollment is the process by which a UA SHOULD make itself known to
the configuration server. In enrolling the UA MUST provide identity
information, name requested configuration data profile and supported
protocols for configuration retrieval. It SHOULD also SUBSCRIBE to
a mechanism for notification of configuration changes. As a result
of enrollment, the UA receives a URL for each of the configuration
data profiles that the configuration server is able to provide.
Each profile requires a separate enrollment or SUBSCRIBE session.
Configuration Retrieval is the process of retrieving the content for
each of the configuration data profiles the UA requested.
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A Framework for SIP Feb. 2003
User Agent Configuration
Change Notification is the process by which the configuration server
notifies the UA that the content of one or more of the configuration
data profiles has changed. Subsequently the UA SHOULD retrieve the
data profile from the specified URL upon receipt of the change
notification.
Configuration Upload is the process by which a UA or other entity
pushes a change to a configuration data profile back up to the
configuration server.
2 Conventions used in this document
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 [1].
The syntax and semantics used here extend those defined in SIP (RFC
2543) [6]. SIP is described in an augmented Backus-Naur form (ABNF).
See [6, section C] for an overview of ABNF.
3 Changes from Previous Draft
3.1 Changes from draft-petrie-sipping-config-framework-00.txt
Changed name to reflect SIPPING work group item Copyright Notice
Updated with changes to SIP DHCP [3], SIP [6], SIP Events [7] and Copyright (C) The Internet Society (2003). All Rights Reserved.
content indirection [15].
Moved the device identity parameters from the From field parameters Abstract
to User-Agent header parameters.
Many thanks to Rich Schaaf of Pingtel, Cullen Jennings of Cisco and This document defines the application of a set of protocols for
Adam Roach of Dyamicsoft for the great comments and input. providing profile data to SIP user agents. The objective is to
define a means for automatically providing profile data a user agent
needs to be functional without user or administrative intervention.
The framework for discovery, delivery, notification and updates of
user agent profile data is defined here. As part of this framework a
new SIP event package is defined here for the notification of profile
changes. This framework is also intended to ease ongoing
administration and upgrading of large scale deployments of SIP user
agents. The contents and format of the profile data to be defined is
outside the scope of this document.
3.2 Changes from draft-petrie-sip-config-framework-01.txt Table of Contents
Changed the name as this belongs in the SIPPING work group. 1. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1 Requirements Terminology . . . . . . . . . . . . . . . . . . 3
2.2 Profile Delivery Framework Terminology . . . . . . . . . . . 4
2.3 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Profile Change Event Notification Package . . . . . . . . . 5
3.1 Event Package Name . . . . . . . . . . . . . . . . . . . . . 6
3.2 Event Package Parameters . . . . . . . . . . . . . . . . . . 6
3.3 SUBSCRIBE Bodies . . . . . . . . . . . . . . . . . . . . . . 7
3.4 Subscription Duration . . . . . . . . . . . . . . . . . . . 7
3.5 NOTIFY Bodies . . . . . . . . . . . . . . . . . . . . . . . 8
3.6 Notifier processing of SUBSCRIBE requests . . . . . . . . . 8
3.7 Notifier generation of NOTIFY requests . . . . . . . . . . . 9
3.8 Subscriber processing of NOTIFY requests . . . . . . . . . . 10
3.9 Handling of forked requests . . . . . . . . . . . . . . . . 10
3.10 Rate of notifications . . . . . . . . . . . . . . . . . . . 10
3.11 State Agents . . . . . . . . . . . . . . . . . . . . . . . . 10
3.12 Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.13 Use of URIs to Retrieve State . . . . . . . . . . . . . . . 11
4. Profile Delivery Framework Details . . . . . . . . . . . . . 12
4.1 Discovery of Subscription URI . . . . . . . . . . . . . . . 12
4.2 Enrollment with Profile Server . . . . . . . . . . . . . . . 13
4.3 Notification of Profile Changes . . . . . . . . . . . . . . 13
4.4 Retrieval of Profile Data . . . . . . . . . . . . . . . . . 14
4.5 Upload of Profile Changes . . . . . . . . . . . . . . . . . 14
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . 14
6. Security Considerations . . . . . . . . . . . . . . . . . . 14
6.1 Symmetric Encryption of Profile Data . . . . . . . . . . . . 14
6.2 Client Certificate Authentication with HTTPS . . . . . . . . 15
6.3 HTTPS Authentication . . . . . . . . . . . . . . . . . . . . 15
7. Differences from Simple XCAP Package . . . . . . . . . . . . 15
8. Open Issues . . . . . . . . . . . . . . . . . . . . . . . . 16
9. Change History . . . . . . . . . . . . . . . . . . . . . . . 16
9.1 Changes from draft-ietf-sipping-config-framework-00.txt . . 16
9.2 Changes from draft-petrie-sipping-config-framework-00.txt . 17
9.3 Changes from draft-petrie-sip-config-framework-01.txt . . . 17
9.4 Changes from draft-petrie-sip-config-framework-00.txt . . . 17
References . . . . . . . . . . . . . . . . . . . . . . . . . 18
Author's Address . . . . . . . . . . . . . . . . . . . . . . 20
A. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . 20
Intellectual Property and Copyright Statements . . . . . . . 21
Minor edits 1. Motivation
3.3 Changes from draft-petrie-sip-config-framework-00.txt Today all SIP user agent vendors use proprietary means of delivering
user or device profiles to the user agent. The profile delivery
framework defined in this document is intended to enable a first
phase migration to a standard means of providing profiles to SIP user
agents. It is expected that UA vendors will be able to use this
framework as a means of delivering their existing proprietary user
and device data profiles (i.e. using their existing proprietary
binary or text formats). This in itself is a tremendous advantage in
that a SIP environment can use a single profile delivery server for
profile data to user agents from multiple vendors. Follow-on
standardization activities can:
1. define a standard profile content format framework (e.g. XML with
name spaces [??] or name-value pairs [RFC0822]).
2. specify the content (i.e. name the profile data parameters, xml
schema, name spaces) of the data profiles.
Many thanks to those who contributed and commented on the previous One of the objectives of the framework described in this document is
draft. Detailed comments were provided by Henning Schulzrinne from to provide a start up experience similar to that of users of an
Columbia U., Cullen Jennings from Cisco, Rohan Mahy from Cisco, Rich analog telephone. When you plug in an analog telephone it just works
Schaaf from Pingtel. (assuming the line is live and the switch has been provisioned).
There is no end user configuration required to make analog phone work
(at least in a basic sense). So the objective here is to be able to
take a new SIP user agent out of the box, plug it in (or install the
software) and have it get its profiles without human intervention
(other than security measures). This is necessary for cost effective
deployment of large numbers of user agents.
Split the enrollment into a single SUBSCRIBE dialog for each Another objective is to provide a scalable means for on going
profile. The 00 draft sent a single SUBSCRIBE listing all of the administration of profiles. Administrators and users are likely to
desired. These have been split so that each enrollment can be want to make changes to user and device profiles.
routed differently. As there is a concept of device specific and
Petrie Informational - Expires Aug. 2003 4 Additional requirements for the framework defined in this document
A Framework for SIP Feb. 2003 are described in: [I-D.ietf-sipping-ua-prof-framewk-reqs],
User Agent Configuration [I-D.sinnreich-sipdev-req]
user specific profiles, these may also be managed on separate 2. Introduction
servers. For instance in a roaming situation the device might get
itĂs configuration from a local server which knows the LAN specific
configuration. At the same time the user specific profiles might
come from the userĂs home environment configuration server.'
Removed the Config-Expires header as it is largely superfluous with 2.1 Requirements Terminology
the SUBSCRIBE Expires header.
Eliminated some of the complexity in the discovery mechanism. Keywords "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT" and
"MAY" that appear in this document are to be interpreted as described
in RFC 2119[RFC2119].
Suggest caching information discovered about a configuration server 2.2 Profile Delivery Framework Terminology
to avoid an avalanche problem when a whole building full of devices
powers up.
Added the User-Profile From header field parameter so that the profile - data set specific to a user or device.
device can a request a user specific profile for a user that is device - SIP user agent, either software or hardware appliance.
different from the deviceĂs default user. profile content server - The server that provides the content of the
profiles using the protocol specified by the URL scheme.
notifier - The SIP user agent server which processes SUBSCRIBE
requests for events and sends NOTIFY requests with profile URL(s).
profile delivery server - The logical collection of the SIP notifier
and the server which provides the contents of the profile URL(s).
4 Discovery 2.3 Overview
The purpose of discovery is to figure out how to address the The profile life cycle can be described by five functional steps.
configuration server so that the device can enroll. The enrollment These steps are not necessarily discrete. However it is useful to
process involves sending a SIP SUBSCRIBE. Prior to this the describe these steps as logically distinct. These steps are named
discovery process must find the address to use in the URL for the as follows:
URI and To header field. The URL SHOULD use the user id:
sipuaconfig. From a SIP perspective the configuration server is
simply a user agent. By using the well known user id, this makes it
easy for proxy servers to be provisioned to route the enrollment
requests from devices to the appropriate configuration server for
the domain.
The first time a UA is plugged in it does not know the address or Discovery - discover a profile delivery server
port at which to enroll with the local configuration server. It Enrollment - enroll with the profile delivery server
must discover this address and port. A UA SHOULD support all of the Profile Retrieval - retrieve profile data
listed discovery mechanisms. It MUST support at least one of them. Profile Change Notification - receive notification of profile changes
Once the UA has discovered the address and port and has successfully Profile Change Upload - upload profile data changes back to the
enrolled with the configuration server, the UA SHOULD cache the profile delivery server
address and port to avoid the need to re-discover the configuration
server. However if enrollment, configuration retrieval or
configuration upload fails at any time, the UA SHOULD apply the
discovery and enrollment process again. This provides a means for
configuration server fail over and load balancing.
The UA SHOULD use the following mechanisms to discover the host
address and port at which it SHOULD enroll with the configuration
server. Each mechanism should be tried in the following order until
an address and port is provided which results in successful
enrollment (i.e. the server responds with a successful 2xx class
response):
- DHCP option for SIP [3]
- DNS A record
- Multicast
- Manual provisioning
Petrie Informational - Expires Aug. 2003 5 Discovery is the process by which a UA SHOULD find the address and
A Framework for SIP Feb. 2003 port at which it SHOULD enroll with the profile delivery server. As
User Agent Configuration there is no single discovery mechanism which will work in all network
environments, a number of discovery mechanisms are defined with a
prescribed order in which the UA SHOULD try them until one succeeds.
The rationale for this order follows. Assuming that most UAs are Enrollment is the process by which a UA SHOULD make itself known to
going to use DHCP for IP configuration anyway, using a DHCP option the profile delivery server. In enrolling the UA MUST provide
is the least costly in terms of lookup time (i.e. no additional identity information, name requested profile type(s) and supported
messages are required). Hence DHCP is first. Multicast is used protocols for profile retrieval. It SHOULD also subscribe to a
last of the automated discovery mechanisms as it is the most mechanism for notification of profile changes. As a result of
restricted in terms of network environments that support it. enrollment, the UA receives a URL for each of the profiles that the
Multicast is included, even though the applicable environments are profile delivery server is able to provide. Each profile type (set)
restricted, as it is the only mechanism that can be used without the requires a separate enrollment or SUBSCRIBE session.
support of the local network administrator.
The phone administrator and the network administrator are often Profile Retrieval is the process of retrieving the content for each
different people and perhaps in different departments. of the profiles the UA requested.
The UA implementer MAY provide the user or administrator with the Profile Change Notification is the process by which the profile
means to change the order in which these mechanisms are tried. This delivery server notifies the UA that the content of one or more of
includes the ability to manually override the discovery process. the profiles has changed. Subsequently the UA SHOULD retrieve the
However by default without user interaction the UA SHOULD use the profile from the specified URL upon receipt of the change
order listed above. notification.
Once discovery is successful the device SHOULD persistently cache Profile Upload is the process by which a UA or other entity (e.g.
the address to avoid avalanche problems when a whole building full OSS, corporate directory or configuration management server) pushes a
of devices powers up at once. The characteristic of the profile may change to the profile data back up to the profile delivery server.
dictate this behavior. For example device specific profiles may
need to change when the device is moved to a different location.
User specific profiles may be independent of the LAN, network or
device location.
4.1 DHCP Option This framework defines a new SIP event package [RFC3265] to solve
enrollment and profile change notification steps.
It is likely that most UAs in an deployment of any significant size The question arises as to why SIP should be used for the profile
will use DHCP for IP configuration. DHCP becomes a convenient means to delivery framework. In this document SIP is used for only a small
discover the configuration server address. In the same DHCP request portion of the framework. Other existing protocols are more
for basic IP configuration, the UA can add the option for SIP[3] [1] to appropriate for transport of the profile contents (upstream and
the options field. This indicates a request for the default SIP proxy downstream of the user agent) and are suggested in this document.
server address and port. For example if the DHCP option for SIP The discovery step is simply a specified order and application of
returns an address of sip.acme.com and a port of 5080, the following existing protocols. SIP is only needed for the enrollment and change
URL is constructed: sip:sipuaconfig@sip.acme.com:5080. If the proxy notification functionality of the profile delivery framework. In
server address and port is not returned in the DHCP response or the many SIP environments (e.g. carrier/subscriber and multi-site
server does not respond to the enrollment request with a successful 2xx enterprise) firewall, NAT and IP addressing issues make it difficult
class response, the next discovery mechanism is attempted. to get messages between the profile delivery server and the user
agent requiring the profiles.
4.2 DNS With SIP the users and devices already are assigned globally routable
addresses. In addition the firewall and NAT problems are already
presumably solved in the environments in which SIP user agents are to
be used. Therefore SIP is the best solution for allowing the user
agent to enroll with the profile delivery server which may require
traversal of multiple firewalls and NATs. For the same reason the
notification of profile changes is best solved by SIP.
The UA SHOULD construct a fully qualified host name using It is assumed that the content delivery server MUST be either in the
˘sipuaconfig÷ as the host and the local domain if defined. It public network or accessible through a DMZ. The user agents
SHOULD try a DNS A record lookup on the fully qualified host name. requiring profiles may be behind firewalls and NATs and many
If the name resolves in DNS it should then attempt enrollment. For protocols, such as HTTP, may be used for profile content retrieval
example the URL constructed in the local domain of acme.com would without special consideration in the firewalls and NATs.
look like: sip:sipuaconfig@sipuaconfig.acme.com. If the server does
not respond to enrollment with a successful 2xx class response, the
next discovery mechanism is attempted.
Petrie Informational - Expires Aug. 2003 6 A conscious separation of user and device profiles is made in this
A Framework for SIP Feb. 2003 document. This is useful to provide features such as hoteling as
User Agent Configuration well as securing or restricting user agent functionality. By
maintaining this separation, a user may walk up to someone else's
user agent and direct that user agent to get their profile data. In
doing so the user agent can replace the previous user's profile data
while still keeping the devices profile data that may be necessary
for core functionality and communication described in this document.
4.3 Multicast 3. Profile Change Event Notification Package
The enrollment request is sent to the multicast address for SIP This section defines a new SIP event package [RFC3265]. The purpose
registration [6] "sip.mcast.net" (224.0.1.75). If a server does not of this event package is to send to subscribers notification of
respond with a successful 2xx class response to the enrollment content changes to the profile(s) of interest and to provide the
request, the next discovery mechanism is attempted. location of the profile(s) via content indirection
[I-D.ietf-sip-content-indirect-mech].
4.4 Manually Provisioned 3.1 Event Package Name
The UA MAY indicate to the user (or administrator) that automatic The name of this package is "sip-profile". This value appears in the
discovery has failed. The UA SHOULD allow the user or administrator Event header field present in SUBSCRIBE and NOTIFY requests for this
to manually (perhaps using some out of band method e.g. beam, smart package as defined in [RFC3265].
card, etc.) enter the configuration server address and port to be
used for enrollment.
5 Enrollment and Change Notification 3.2 Event Package Parameters
The enrollment and configuration change notification are paired This package defines the following new parameters for the event
together and provided via the SIP SUBSCRIBE/NOTIFY framework [7]. header: profile-type, vendor, model, version, effective-by. The
This document defines the profile on top of the SUBSCRIBE/NOTIFY effective-by parameter is for use in NOTIFY requests only. The
framework [7] for this purpose. others are for use in the SUBSCRIBE request, but may be used in
NOTIFY requests as well.
UA enrollment with the configuration server is accomplished via the The profile-type parameter is used to indicate the profile type the
SUBSCRIBE request. A UA MUST enroll with the configuration server user agent wishes to obtain URLs for and be notified of change. This
prior to retrieving configuration data profiles. As part of the parameter allows the URL semantics to be opaque to the subscribing
enrollment the UA MUST identify itself, its configuration retrieval user agent as all it needs to know is the token value for this
protocol capabilities and configuration data profile requirements. parameter. This document defines two type categories of profiles.
The contents or format of the profiles is outside the scope of this
document. The two types of profiles define here are "user" and
"device". Specifying device type profile(s) indicates the desire for
the URL(s) and change notification of all profiles that are specific
to the device or user agent. Specifying user type profile(s)
indicates the desire for the URL(s) and change notification of all
profile(s) that are specific to the user. The user or device is
identified in the URI of the SUBSCRIBE request. The Accept header of
the SUBSCRIBE request MUST include the MIME types for all profile
content types that the subscribing user agent wishes to retrieve
profiles or receive change notifications.
The configuration server may use this information to decide how to The user or device token in the profile-type parameter may
allocate resources (e.g. load balancing) to support the UA for its represent a class or set of profiles as opposed to a single
specific configuration retrieval needs. The configuration server profile. As standards are defined for specific profile contents
may also use the UA enrollment event as the trigger to generate a related to the user or device, it may be desirable to define
new set of configuration data for the specific UA (e.g. based upon additional tokens for the profile-type header. This is to allow a
provisioned defaults and configuration profile context knowledge for user agent to subscribe to that specific profile as opposed to the
the environment). This allows the configuration server to provide entire class or set of user or device profiles.
configuration data for a new UA without previously provisioning the
specific UA on the server.
Each profile that the device requires is obtained via a separate The rational for the separation of user and device type profiles is
enrollment or SUBSCRIBE request and SIP dialog. That is for each provided in section Section 2.3. It should be noted that either type
different profile a device enrolls for, a different Call-Id is used. may indicate that zero or more URLs are provided in the NOTIFY
The device names the profile MIME type in the SUBSCRIBE Accept request. As discussed, a default user may be assigned to a device.
header field. The configuration server then delivers a URL (through In this scenario the profile delivery server may provide the URL(s)
content indirection [15]) at which the device can retrieve the in the NOTIFY request for the default user when subscribing to the
profile in a subsequent NOTIFY request. Changes to the profile are device profile type. Effectively the device profile type becomes a
indicated in additional NOTIFY requests sent from the configuration superset of the user profile type subscription. The user type is
server. still useful in this scenario to allow the user agent to obtain
profile URLs for a user other than the default user. This provides
the ability to support a hoteling function where a user may "login"
to any user agent and have it use a users profile(s).
The SUBSCRIBE request for enrollment is sent to the address(es) The vendor, model and version parameters are tokens specified by the
identified in the discovery process until the first successful 2xx vendor of the user agent. These parameters are useful to the profile
class response is received. As part of the binding of the delivery server to effect the profiles provided. In some scenarios
SUBSCRIBE/NOTIFY framework a new MIME type must be named for each it is desirable to provide different profiles based upon these
parameters. For example feature parameter X in a profile may work
differently on two versions of user agent. This gives the profile
deliver server the ability to compensate for or take advantage of the
differences.
Petrie Informational - Expires Aug. 2003 7 The "effective-by" parameter in the Event header of the NOTIFY
A Framework for SIP Feb. 2003 specifies the maximum number of seconds before the user agent MUST
User Agent Configuration make the new profile effective. A value of 0 (zero) indicates that
the user agent MUST make the profiles effective immediately (despite
possible service interruptions). This gives the profile delivery
server the power to control when the profile is effective. This may
be important to resolve an emergency problem or disable a user agent
immediately.
type of profile. The profile(s) MIME type(s) MUST be included in SUBSCRIBE request example:
the SUBSCRIBE Accept header field. Event: sip-profile;profile-type=device;
vendor=acme;model=Z100;version=1.2.3
[Is it ok to allow a single SUBSCRIBE to request multiple profile NOTIFY request examples:
types in (e.g. for each MIME subtype application/sip-ua-user-profile Event:sip-profile;effective-by=0
and application/sip-ua-device-profile)?]
If enrollment fails (i.e. no 2xx response to SUBSCRIBE), the UA Event:sip-profile;effective-by=3600
SHOULD re-discover the configuration server address and port as
described in section 3.
5.1 SUBSCRIBE 3.3 SUBSCRIBE Bodies
The SUBSCRIBE request is used by the UA to enroll in the This package defines no new use of the SUBSCRIBE request body.
configuration domain of the configuration server. It uniquely
identifies the UA with vendor, model and serial number information.
The UA also MUST specify its capabilities for configuration
retrieval. The UA MUST indicate support for content indirection by
including the MIME type message/external-body in the SUBSCRIBE
Accept header field per [15].
The configuration server SHOULD not send an error if it is 3.4 Subscription Duration
temporarily not able to provide the configuration data profile
listed in the SUBSCRIBE request Event header field. In the first
time out of the box case, the SUBSCRIBE dialog may be the only means
of communicating with the device as it does not yet have
configuration. The configuration server SHOULD send a 403 response
to the SUBSCRIBE if is not willing to provide the requested
configuration profile to the device. The configuration server
SHOULD provide the configuration data profile to the UA via content
indirection. If the configuration server sends a 301 Moved
Permanently response to the enrollment SUBSCRIBE, the UA SHOULD
cache the URL contained in the response Contact header field in
place of the address and port found during discovery for future
enrollment.
The device may request many configuration data profiles by As profiles are generally static with infrequent changes, it is
sending multiple SUBSCRIBE requests each in a different SIP recommended that default subscription duration be 86400 seconds (one
dialog. This may be useful if the device requires user day).
specific profiles for multiple users. In this case the
UserProfile parameter would vary for each SUBSCRIBE.
Alternately the device may require multiple types of profiles
where each SUBSCRIBE would have a different MIME type in the
Accept header field.
The configuration server MAY use the enrollment (SUBSCRIBE request) 3.5 NOTIFY Bodies
as the stimulus to generate a new instance of a configuration data
profile unique to the UA. Alternately the configuration server MAY
be provisioned ahead of time to know about new UAs and their
specific configuration data content (for example based upon serial
number, MAC address).
Petrie Informational - Expires Aug. 2003 8 The size of profile content is likely to be hundreds to several
A Framework for SIP Feb. 2003 thousand bytes in size. Frequently even with very modest sized SDP
User Agent Configuration bodies, SIP messages get fragmented causing problems for many user
agents. For this reason the NOTIFY body MUST use content indirection
[I-D.ietf-sip-content-indirect-mech] for providing the profiles.
The user agent forms the From field in the SUBSCRIBE in one of two The profile delivery server MUST include the Content-ID defined in
ways depending upon the type of profile that it is enrolling to. If [I-D.ietf-sip-content-indirect-mech] for each profile URL. This is
the user agent is enrolling to a device specific profile, the from to avoid unnecessary download of the profiles. Some user agents are
addr-spec is formed as: sip:<MAC-address>@<local-domain>. If the not able to make a profile effective without rebooting or restarting.
user agent is enrolling to a user specific profile the addr-spec is Rebooting is probably something to be avoided on a user agent
formed as the users address of record. In this way the identity for performing services such as telephony. In this way the Content-ID
which the profile is desired is always specified in the From field. allows the user agent to avoid unnecessary interruption of service as
well. The Content-Type MUST be specified for each URL.
5.1.1 Additional User Agent Field Parameters Initially it is expected that most user agent vendors will use a
proprietary content type for the profiles retrieved from the
URLs(s). It is hoped that over time a standard content type will
be specified that will be adopted by vendors of user agents. One
direction that appears to be promising for this content is to use
XML with name spaces [??] to segment the data into sets that the
user agent implementer may choose to support based upon desired
feature set. The specification of the content is out of the scope
of this document.
When the device first starts up out of the box, it has no user or Likewise the URL scheme used in the content indirection is outside
local configuration. The device MUST provide a unique identity such the scope of this document. This document is agnostic to the URL
that it is possible for the configuration server to generate schemes as the profile content may dictate what is required. It is
configuration profile for the device. The user agent MUST include expected that TFTP [RFC3617], FTP [??], HTTP [RFC2616], HTTPS
the User-Agent header in the SUBSCRIBE request. The following [RFC2818], LDAP [RFC3377], XCAP [I-D.rosenberg-simple-xcap] and other
additional User-Agent field parameters are defined for the purpose URL schemes are supported by this package and framework.
of identifying the UA device:
Vendor ű a token used to identify the UA vendor name 3.6 Notifier processing of SUBSCRIBE requests
Model ű a token used to identify the UA hardware/software model The general rules for processing SUBSCRIBE requests [RFC3265] apply
to this package. The notifier does not need to authenticate the
subscription as the profile content is not transported in the
SUBSCRIBE or NOTIFY transaction messages. Only URLs are transported
in the NOTIFY request which may be secured using the techniques in
section Section 6.
Version ű a token used to identify the firmware/software version The behavior of the profile delivery server is left to the
currently installed on the UA implementer. The profile delivery server may be as simple as a SIP
SUBSCRIBE UAS and NOTIFY UAC front end to a simple HTTP server
delivering static files that are hand edited. At the other extreme
the profile delivery server can be part of a configuration management
system that integrates with a corporate directory and IT system or
carrier OSS, where the profiles are automatically generated. The
design of this framework intentionally provides the flexibility of
implementation from simple/cheap to complex/expensive.
Serial ű the token used to identify the serial number for the UA If the user or device is not known to the profile delivery server,
the implementer MAY accept the subscription or reject it. It is
recommended that the implementer accept the subscription. It is
useful for the profile delivery server to maintain the subscription
as an administrator may add the user or device to the system,
defining the profile contents. This allow the profile delivery
server to immediately send a NOTIFY request with the profile URLs.
If the profile delivery server does not accept the subscription from
an unknown user or device, the administer or user must manually
provoke the user agent to reSUBSCRIBE. This may be difficult if the
user agent and administrator are at different sites.
Note: on some hardware such as PCs and servers, there may be 3.7 Notifier generation of NOTIFY requests
multiple instances of a user agent installed. In these
scenarios only the serial number can be used to uniquely
distinguish instances.
Mac ű the token used to identify the MAC address in hex for the UA As in [RFC3265], the profile delivery server MUST always send a
NOTIFY request upon accepting a subscription. If the device or user
is unknown to the profile delivery server and it chooses to accept
the subscription, the implementer has two choices. A NOTIFY MAY be
sent with no body or content indirection containing the profile
URL(s). Alternatively a NOTIFY MAY be sent with URL(s) pointing to a
default data set. Typically this data set allows for only limited
functionality of the user agent (e.g. a phone user agent with data to
call help desk and emergency services.). This is an implementation
and business policy decision.
From RFC 3261 [6] the User-Agent header field syntax is extended to: A user or device known and fully provisioned on the profile delivery
User-Agent = "User-Agent" HCOLON product *( SEMI config-params ) server SHOULD send a NOTIFY with content indirection containing URLs
for all of the profiles associated with the user or device (i.e.
which ever specified in the profile-type parameter). The device may
be associated with a default user. The URL(s) for this default user
profiles MAY be included with the URL(s) of the device if the profile
type specified is device.
config-params = serial-param / mac-param / generic-param A user agent can provide Hoteling by collecting a userĺs AOR and
product = vendor-model [SLASH product-version] credentials needed to SUBSCRIBE and retrieve the user profiles from
product-version = token the URL(s). Hoteling functionality is achieved by subscribing to the
vendor-param = ˘Vendor÷ ˘=÷ token AOR and specifying the "user" profile type. This same mechanism can
serial-param = ˘Serial÷ ˘=÷ token be used to secure a user agent, requiring a user to login to enable
mac-param = ˘Mac÷ ˘=÷ token functionality beyond the default userĺs restricted functionality.
Example: The profile delivery server MAY specify when the new profiles MUST be
User-Agent: model-a/1.5.0.1;vendor=acme made effective by the user agent. By default the user agent makes
the profiles effective as soon as it thinks that it is non-obtrusive.
The Vendor, Model, Version, Serial and Mac parameters MUST be However the profile delivery server MAY specify a maximum time in
provided in the User-Agent header field for the enrollment SUBSCRIBE seconds (zero or more), in the effective-by event header parameter,
by which the user agent MUST make the new profiles effective.
Petrie Informational - Expires Aug. 2003 9 3.8 Subscriber processing of NOTIFY requests
A Framework for SIP Feb. 2003
User Agent Configuration
request. Most profiles will either be device or user specific. All The user agent subscribing to this event package MUST adhere to the
config-params MUST be specified even when enrolling for user NOTIFY request processing behavior specified in [RFC3265]. The user
profiles as the device characteristics may impact the content that agent MUST make the profiles effective as specified in the NOTIFY
the profile server provides. request (see section Section 3.7). The user agent SHOULD use one of
the techniques specified in section [RFC3265] to securely retrieve
the profiles.
5.2 NOTIFY 3.9 Handling of forked requests
The NOTIFY message is sent by the configuration server to convey the This event package allows the creation of only one dialog as a result
URL at which the UA can retrieve the requested configuration data of an initial SUBSCRIBE request. The techniques to achieve this are
profile. This occurs in two contexts: described in section 4.4.9 of [RFC3265].
Immediately following the enrollment SUBSCRIBE the configuration 3.10 Rate of notifications
server MUST send a NOTIFY providing the URL for the configuration
data profile requested by the UA in the Event header field of the
SUBSCRIBE request. If the configuration server is not able to
provide the specific configuration data profile or it does not
want the UA to retrieve the specific configuration profile at that
time, it MAY defer sending NOTIFY. Later when the configuration
server is able to provide the data profile or it wishes the UA to
retrieve the data profile, the configuration server MAY send a
NOTIFY request containing the URL for the configuration data
profile which the UA SHOULD retrieve and make effective as soon as
it is safe to do so (e.g. when there are no active INVITE
dialogs).
If the configuration server becomes aware of a configuration It is anticipated that the rate of change for user and device
change that it wishes to be effective immediately on the UA, the profiles will be very infrequent (i.e. days or weeks apart). For
configuration server SHOULD send a NOTIFY message containing the this reason no throttling or minimum period between NOTIFY requests
URL for the configuration data profile that the UA requested when is specified for this package.
it enrolled. The configuration data profile with changed content
SHOULD have a different Content-ID entity header than that of the
last NOTIFY request. The UA SHOULD retrieve and make effective
the changed configuration URL immediately upon receipt of the
NOTIFY request. The UA MAY choose to wait to make the changes
effective (e.g. to prevent the change from disrupting active calls
on the UA).
[Do we need an option for the configuration server to tell the UA 3.11 State Agents
that it MUST make the change immediately regardless of state?
Should this be the default?]
The UA SHOULD send a 200 response to the NOTIFY immediately upon State agents are not applicable to this event package.
receipt and validation of the solicited request. The configuration
server MUST include, in the change notification NOTIFY request, the
configuration data profile URL. The Content-ID entity header
associated with the configuration data profile with changed content
should be different than that of the previous NOTIFY.
This mechanism may be used by the configuration server to provide
firmware updates. For example on a UA that caches or has a
persistent firmware image: if the server realizes (e.g. from the
enrollment information) the UA is running the most currently
available firmware version, it could defer sending the NOTIFY with
the URL for the firmware. However at a later time when a new
Petrie Informational - Expires Aug. 2003 10 3.12 Examples
A Framework for SIP Feb. 2003
User Agent Configuration
firmware version is available the configuration server could send SUBSCRIBE sip:00df1e004cd0@example.com SIP/2.0
a NOTIFY with the URL for the new firmware version, indicating the Event: sip-profile;profile-type=device;vendor=acme;
UA SHOULD upgrade as soon as it is safe to do so. model=Z100;version=1.2.3
From: sip:00df1e004cd0@acme.com;tag=1234
To: sip:00df1e004cd0@acme.com;tag=abcd
Call-ID: 3573853342923422@10.1.1.44
CSeq: 2131 SUBSCRIBE
Contact: sip:00df1e004cd0@10.1.1.44
Content-Length: 0
5.2.1 NOTIFY Body Content Format NOTIFY sip:00df1e004cd0@10.1.1.44 SIP/2.0
Event: sip-profile;effective-by=3600
From: sip:00df1e004cd0@acme.com;tag=abcd
To: sip:00df1e004cd0@acme.com;tag=1234
Call-ID: 3573853342923422@10.1.1.44
CSeq: 321 NOTIFY
MIME-Version: 1.0
Content-Type: multipart/mixed; boundary=boundary42
Content-Length: ...
The NOTIFY request MUST contain a single part body with content --boundary42
indirection [15]. The request MUST have a Content-Type header field Content-Type: message/external-body;
with the MIME type of message/external-body. The Content-Type MUST access-type="URL";
also have a URL parameter specifying the URL at which to retrieve the expiration="Mon, 24 June 2002 09:00:00 GMT";
profile. The body MUST contain a Content-Type entity header with the URL="http://www.example.com/devices/fsmith";
MIME type of the profile as the value. The body MUST also contain a size=2222
Content-ID entity header which SHOULD change to a new unique value each
time the content of the URL changes. The Content-ID entity header
associated with the URL is intended to allow the UA to decide if it has
the latest content of the configuration data profile without having to
download and compare the contents.
Example: Content-Type: application/z100-user-profile
Content-ID: <69ADF2E92@example.com>
NOTIFY sip:00df1e004cd0@acme.com SIP/2.0 --boundary42
From: sip:sipuaconfig@sipuaconfig.acme.com;tag=1234
To: sip:00df1e004cd0@acme.com;tag=abcd
Call-ID: 3573853342923422@10.1.1.123
CSeq: 2131 INVITE
Content-Type: message/external-body; Content-Type: message/external-body;
ACCESS-TYPE=URL; access-type="URL";
URL="https://acme.com/profiles/vendor-x/00df1e004cd0" expiration="Mon, 24 June 2002 09:00:00 GMT";
Content-Length: ... URL="http://www.example.com/devices/ff00000036c5";
Content-Type: application/foo-profile size=1234
Content-Disposition: session
Content-ID: <1000957853@acme.com>
6 Configuration Retrieval Content-Type: application/z100-device-profile
Content-ID: <39EHF78SA@example.com>
The UA MUST retrieve its configuration data profile using the URL --boundary42--
specified by the configuration server in the NOTIFY request. If the
retrieval fails, the UA SHOULD not re-enroll until the SUBSCRIBE
session expires to avoid a cascade effect if the server goes down
temporarily. The device MAY re-try the profile retrieve of the
profile from the URL before the SUBSCRIBE expires. Should the re-
enrollment fail, the UA SHOULD re-discover the configuration server
as described in section 4.
7 Configuration Upload 3.13 Use of URIs to Retrieve State
If the UA or another entity wishes to modify a configuration data The profile type specified determines what goes in the user part of
profile it MAY make the change persistent on the configuration the SUBSRIBE URI. If the profile type requested is "device", the
server if it is authorized to do so. The configuration server user part is an identity that MUST be unique across all user agents
SHOULD support the ability to accept uploads via the same URL the UA from all vendors. This identity must be static over time so that the
used to retrieve the configuration data profile. For HTTP and HTTPS profile delivery server can keep it associated with its profiles.
the UA does a POST with a multipart MIME attachment containing any For Ethernet hardware type user agents supporting only a single user
URL parameters in one part and the changed configuration data at a time this is most easily accomplished using its MAC address.
Software based user agents running on general purpose hardware may
also be able to use the MAC address for identity. However in
situations where multiple instance of user agents are running on the
same hardware it may be necessary to use a another scheme, such as
using a unique serial number for the software.
Petrie Informational - Expires Aug. 2003 11 If the profile type request is "user" the URI in the SUBSCRIBE
A Framework for SIP Feb. 2003 request is the address of record for the user. This allows the user
User Agent Configuration to specify (e.g. login) to the user agent by simply entering their
known identity.
profile [whole or changes only ?? define in profiles ??] in another 4. Profile Delivery Framework Details
part as defined in [?]. If the UA or user is not permitted to make
the changes on the configuration server the configuration server
returns an HTTP error response code of 403 Forbidden. If the
configuration server returns a 403 the UA SHOULD disallow the
changes from being effective on the UA. The UA SHOULD not make the
changes effective until it receives a successful response (e.g. for
HTTP 2xx).
If the URL is for HTTP/HTTPS the server MUST return the changed The following describes how different functional steps of the profile
configuration data profile in the response (assuming it was delivery framework work. Also described here is how the event
allowed). The UA SHOULD use the configuration data profile contents package defined in this document provides the enrollment and
from the HTTP response as opposed to the data that was pushed in the notification functions within the framework.
request as changes may occur from other sources. The server SHOULD
include a Content-ID header in the HTTP/HTTPS response. The
configuration server SHOULD send out a NOTIFY for this change, using
the same Content-ID entity header value as in the HTTP/HTTPS
response. This allows the UA to know that it already has the current
contents of the configuration data profile and SHOULD not download
that configuration data profile (i.e. it is safe to ignore the
NOTIFY as the Content-ID is the same).
[Alteratively the Content-ID could be put in the content as opposed 4.1 Discovery of Subscription URI
to the HTTP/HTTPS response]
[TBD ű in 403 case restrict and provide feedback as to what The discovery function is needed to bootstrap user agents to the
specifically is not allowed to be modified by the UA or user] point of knowing where to enroll with the profile delivery server.
Section Section 3.13 describes how to form the URI used to sent the
SUBSCRIBE request for enrollment. However the bootstrapping problem
for the user agent (out of the box) is what to use for the host and
port in the URI. Due to the wide variation of environments in which
the enrolling user agent may reside (e.g. behind residential router,
enterprise LAN, ISP, dialup modem) and the limited control that the
administrator of the profile delivery server (e.g. enterprise,
service provider) may have over that environment, no single discovery
mechanism works everywhere. Therefore a number of mechanisms SHOULD
be tried in the specified order: SIP DHCP option [RFC3361], SIP DNS
SRV [RFC3263], DNS A record and manual.
8 Examples 1. The first discovery mechanizm that SHOULD be tried is to
construct the SUBSCRIBE URI as described in Section 3.13 using
the host and port of out bound proxy discovered by the SIP DHCP
option as described in [RFC3361]. If the SIP DHCP option is not
provided in the DHCP response, no SIP response or a SIP failure
response other than for authorization is received for the
SUBSCRIBE request to the sip-profile event, the next discovery
mechanism SHOULD be tried.
2. The local IP network domain for the user agent, either configured
or discovered via DHCP, should be used with the technique in
[RFC3263] to obtain a host and port to use in the SUBSCRIBE URI.
If no SIP response or a SIP failure response other than for
authorization is received for the SUBSCRIBE request to the
sip-profile event, the next discovery mechanism SHOULD be tried.
3. The fully qualified host name constructed using the host name
"sipuaconfig" and concatenated with the local IP network domain
should be tried next using the technique in [RFC3263] to obtain a
host and port to use in the SUBSCRIBE URI. If no SIP response or
a SIP failure response other than for authorization is received
for the SUBSCRIBE request to the sip-profile event, the next
discovery mechanism SHOULD be tried.
4. If all other discovery techniques fail, the user agent MUST
provide a manual means for the user to enter the host and port
used to construct the SUBSCRIBE URI.
Below is an example high level message flow for a new UA discovering Once a user agent has successfully discovered, enrolled, received a
and using configuration data from a configuration server. Following NOTIFY response with profile URL(s), the user agent SHOULD cache the
the high level message flows are some specific SIP messages SUBCRIBE URI to avoid having to rediscover the profile delivery
illustrating SUBSCRIBE and NOTIFY messages from enrollment and server again in the future. The user agent SHOULD NOT cache the
configuration change notification. SUBSCRIBE URI until it receives a NOTIFY with profile URL(s). The
reason for this is that a profile delivery server may send 202
responses to SUBSCRIBE requests and NOTIFY responses to unknown user
agent (see section Section 3.6) with no URLs. Until the profile
delivery server has sent a NOTIFY request with profile URL(s), it has
not agreed to provide profiles.
8.1 Example Message Flows To illustrate why the user agent should not cache the SUBSCRIBE
URI until profile URL(s) are provided in the NOTIFY, consider the
following example: a user agent running on a laptop plugged into
a visited LAN in which a foreign profile delivery server is
discovered. The profile delivery server never provides profile
URLs in the NOTIFY request as it is not provisioned to accept the
user agent. The user then takes the laptop to their enterprise
LAN. If the user agent cached the SUBSCRIBE URI from the visited
LAN (which did not provide profiles), the user agent would not
attempt to discover the profile delivery server in the enterprise
LAN which is provisioned to provide profiles to the user agent..
The following high level message flows illustrate the configuration 4.2 Enrollment with Profile Server
process of discovery, enrollment, configuration retrieval and change
notification with associated configuration retrieval. The UA uses
DHCP with the SIP [3] option requesting the configuration server
address and port. The DHCP server does not provide the
configuration server address or port. The UA then does a DNS lookup
for the configuration service within the local domain. It gets a
response from the DNS server for the configuration serverĂs fully
qualified host name. The UA then enrolls with the configuration
server by sending a SUBSCRIBE request for the profile type indicated
in the Event header. The configuration server sends back a
successful response. The configuration server then sends a NOTIFY
request with the URL for the configuration data profile that the UA
named in the enrollment SUBSCRIBE request. The UA sends a 200
response to the NOTIFY. The UA then downloads the configuration
Petrie Informational - Expires Aug. 2003 12 Enrollment is accomplished by subscribing to the event package
A Framework for SIP Feb. 2003 described in section Section 3. The enrollment process is useful to
User Agent Configuration the profile delivery server as it makes the server aware of user
agent to which it may delivery profiles (those user agents the
profile delivery server is provisioned to provide profiles to; those
present that the server may be provide profiles in the future; and
those that the server can automatically provide default profiles).
It is an implementation choice and business policy as to whether the
profile delivery server provides profiles to user agents that it is
not provisioned to do so. However the profile server SHOULD accept
(with 2xx response) SUBSCRIBE requests from any user agent.
data profile via the URL from the NOTIFY request. This process may 4.3 Notification of Profile Changes
be repeated in parallel for each of the required profiles. The UA
is now configured as prescribed.
Later ... an administrator makes a change to the configuration for The NOTIFY request in the sip-profile event package server two
the UA on the configuration server. The configuration server on purposes. First it provides the user agent with a means to obtain
behalf of the administrator, sends a NOTIFY (change notification) the URL(s) for desired profiles without requiring the end user to
request to the UA with Content-ID entity header for the profile. As manually enter them. It also provides the means for the profile
the Content-ID value has changed, the UA downloads the configuration delivery server to notify the user agent that the content of the
data profile from the given URL. profiles have changed and should be made effective.
UA DHCP Server DNS Server Config. Server 4.4 Retrieval of Profile Data
Discovery The user agent retrieves it's needed profile(s) via the URL(s)
provide in the NOTIFY request as specified in section Section 3.5.
The profile delivery server SHOULD secure the content of the profiles
using one of the techniques described in Section 6. The user agent
SHOULD make the new profiles effective in the timeframe described in
section Section 3.2.
IP config. req. The contents of the profiles SHOULD be cached by the user agent.
==============> This it to avoid the situation where the content delivery server is
IP config. wo/ local option not available, leaving the user agent non-functional.
<==============
DNS A record req. for sipuaconfig host in local domain
=============================>
A record IP address returned for Host
<=============================
Enrollment 4.5 Upload of Profile Changes
SIP SUBSCRIBE Event: sip-config The user agent or other service MAY push changes up to the profile
==================================================> delivery server using the technique appropriate to the profile's URL
200 OK scheme (e.g. HTTP PUT method, FTP put command). The technique for
<================================================== pushing incremental or atomic changes MUST be described by the
SIP NOTIFY Event: sip-config w/ requested profile URL specific profile data framework.
<==================================================
200 OK
==================================================>
Configuration retrieval 5. IANA Considerations
HTTP GET [TBD]
==================================================>
200 OK (specific profile data in body)
<==================================================
.
.
.
Administrative change on configuration server via user interface 6. Security Considerations
.
.
.
Petrie Informational - Expires Aug. 2003 13 Profiles may contain sensitive data such as user credentials. The
A Framework for SIP Feb. 2003 protection of this data is accomplished via the profile retrieval
User Agent Configuration function. This simplifies the security solution as the SIP event
package does not need to authenticate, authorize or protect the
contents of the SIP messages. Effectively the profile delivery
server will provide profile URL(s) to any one. The URLs themselves
are protected via authentication, authorization and snooping. Three
options for secure retrieval of profiles are follow:
Change Notification 6.1 Symmetric Encryption of Profile Data
SIP NOTIFY Event: sip-config w/ changed profile URL One security technique is to encrypted the profiles on the content
<================================================== delivery server using the AES symmetric encryption algorithm using a
200 OK key formed by a MD5 hash of the following: username ":" password.
==================================================> The encrypted profiles are delivered by the content delivery server
HTTP GET via the URLs provided in the NOTIFY requests. Using this technique
==================================================> the profile delivery server does not need to provide authentication
200 OK (profile data in body) or authorization for the retrieval as the profiles are obscured. The
<================================================== user agent must obtain the username and password from the user to
. generate the key and perform AES decryption the profiles. This is
. the simplest security technique as it does not require any public key
. infrastructure or TLS implementation on the user agent (which often
has limited resources).
User changes data in a profile on the user agent 6.2 Client Certificate Authentication with HTTPS
.
.
.
Configuration Upload In another technique the content delivery server authenticates the
user or user agent by requesting the client's certificate in the TLS
connection established as described by the profile URL. The content
delivery server authorizes the profile retrieval using the
certificate identity and business policy choices provide by the
server implementer. The profile data is obscured from snooping using
the encryption mechanisms provide by the TLS connect. This has nice
properties of not requiring end user intervention, but has a higher
administrative cost for user agent certificate management and
distribution. It also requires the certificates to be in place
before enabling profile delivery.
HTTP POST (changed profile attached as multipart MIME) 6.3 HTTPS Authentication
==================================================>
200 OK (profile data in body, as change confirmation)
<==================================================
.
.
.
8.2 Example Messages Alternatively the authentication mechanizms described in [RFC2617]
are used. The content delivery server authorizes the profile
retrieval using the certificate identity and business policy choices
provide by the server implementer. The profile data is obscure from
snooping using the encryption mechanisms provide by the TLS connect.
This also requires the overhead of a TLS implementation on the user
agent.
Petrie Informational - Expires Aug. 2003 14 For all of these techniques the user agent should take care in how it
A Framework for SIP Feb. 2003 stores or caches the profiles to avoid theft. It is recommended that
User Agent Configuration a symmetric encryption technique such as that described in section
Section 6.1 be used. This also requires the overhead of a TLS
implementation on the user agent.
The following SUBSCRIBE request example is from a UA enrolling with 7. Differences from Simple XCAP Package
a configuration server. As this SUBSCRIBE request is for
configuration enrollment the Event header field contains the token
sip-config. The UA tells the configuration server that it would
like the configuration data profile of type: sip-ua-device-config in
the Accept header field. The UA tells the configuration server that
it is enrolling for 86400 seconds via the Expires header field.
During this period of time the configuration server MUST send a
change notification with the URL for the configuration data profile
which changed. The UA has identified the specifics about itself in
the From field addr-spec and User-Agent parameters: Vendor/Model,
Version, Serial, Mac. In this example the UserProfile parameter is
not included in the From field as the sip-config profile is device
specific not user specific.
UA => Config. Server The author of this document had an action item from the July 2003
IETF SIPPING WG meeting to consider resolving the differences of the
sip-profile and simple XCAP package [I-D.ietf-simple-xcap-package].
It is the author's opinion that XCAP [I-D.rosenberg-simple-xcap] can
be supported by the framework and event package defined in this
document as it is simply a URL using the HTTP or HTTPS scheme. The
following lists the differences between the event packaged defined in
this document vs. the one defined in [I-D.ietf-simple-xcap-package].
SUBSCRIBE sip: sipuaconfig@config.localdomain.com SIP/2.0 The simple XCAP package requires that the relative path be known and
To: sip:sipuaconfig@sipuaconfig.localdomain.com specified by the user agent when subscribing for change notification.
From: sip:000aaa1234cd@localdomain.com;tag=aslkjhd The event package in this document requires a token be known and
User-Agent: acme-model-a/1.5.0.1;Serial=1234567890;Mac=000aaa1234cd specified when subscribing. The advantage of the latter is that
Call-Id: 987654321@10.1.1.123 bootstrapping is easier and well defined. It also leaves the freedom
Cseq: 1 SUBSCRIBE of specifying the entire path of the profile URL up to the profile
Event: sip-config delivery server.
Expires: 86400
Content-Length: 0
Accept: message/external-body application/sip-ua-device-config
The following is an example response to the above enrollment The event package defined in this document allows multiple URLs to be
request. provided in the NOTIFY request body as a result of a single token
specified in the SUBSCRIBE event parameter: profile-type. This
allows the profile delivery server to provide sets of profiles that
the user agent may not have enough information to specify in the
SUBSCRIBE URI (e.g. at boot strapping time the user agent may not
know the user's identity, but the profile delivery server may know
the default user for the device's identity) or the doc-component of
the simple XCAP package.
Config. Server => UA The simple XCAP package provides profile data changes or deltas in
the body of the NOTIFY request. This is a desirable feature, but
approach in the simple XCAP package has a few disadvantages:
SIP/2.0 202 Accepted o SIP signaling requires authentication, authorization and
To: sip:sipuaconfig@sipuaconfig.localdomain.com;tag=owiu1234 encryption (SIPS) to protect the profiles where the event package
From: sip:000aaa1234cd@localdomain.com;tag=aslkjhd in this document does not. SIPS may require more resources than
Call-Id: 987654321@10.1.1.123 are available on many user agents.
Cseq: 1 SUBSCRIBE o The content of a profile change may be large, causing
Content-Length: 0 fragmentation and problems or constraints when using UDP.
Petrie Informational - Expires Aug. 2003 15 The feature of providing profile data changes or deltas can be
A Framework for SIP Feb. 2003 provided in the package proposed in this document by providing two
User Agent Configuration URLs in the NOTIFY request for each profile (i.e. a URL for the
complete profile and another for the changes).
In the following example the device is requesting a user specific All other functional differences between
profile Sip-User. The device specifies that it want the profile for draft-ietf-sipping-config-framework-00 and
the user: sip:fredsmith@localdomain.com. draft-ietf-simple-xcap-package-00 are believed to be resolved in this
version of this document.
UA => Config. Server 8. Open Issues
SUBSCRIBE sip: sipuaconfig@sipuaconfig.localdomain.com SIP/2.0 9. Change History
To: sip:sipuaconfig@sipuaconfig.localdomain.com
From: sip:fredsmith@localdomain.com;tag=klhfkjncd
User-Agent: acme-model-a/1.5.0.1;Serial=1234567890;Mac=000aaa1234cd
Call-Id: 11111111@10.1.1.123
Cseq: 1 SUBSCRIBE
Event: sip-config
Expires: 86400
Content-Length: 0
Accept: message/external-body application/sip-ua-user-config
The following is an example response to the above enrollment 9.1 Changes from draft-ietf-sipping-config-framework-00.txt
request.
Config. Server => UA This version of the document was entirely restructured and re-written
from the previous version as it had been micro edited too much.
SIP/2.0 202 Accepted All of the aspects of defining the event package are now organized in
To: sip:sipuaconfig@sipuaconfig.localdomain.com;tag=oqieu983 one section and is believed to be complete and up to date with
From: sip:fredsmith@localdomain.com;tag=klhfkjncd [RFC3265].
Call-Id: 11111111@10.1.1.123
Cseq: 1 SUBSCRIBE
Content-Length: 0
The following example is the immediate NOTITY request the The URI used to subscribe to the event package is now either the user
configuration server sent to the UA above enrollment. The URL in or device address or record.
the request body is for the configuration data profile the UA named
in the Event header field in the above SUBSCRIBE request from the
UA.
Config. Server => UA The user agent information (vendor, model, MAC and serial number) are
now provided as event header parameters.
NOTIFY sip:10.1.1.123 SIP/2.0 Added a mechanism to force profile changes to be make effective by
To: sip:sipuaconfig@sipuaconfig.localdomain.com;tag=owiu1234 the user agent in a specified maximum period of time.
From: sip:000aaa1234cd@localdomain.com;tag=aslkjhd
Call-Id: 987654321@10.1.1.123
Cseq: 22 NOTIFY
Event: sip-config
Content-Type: message/external-body;ACCESS-TYPE=URL;
URL="http://config.localdomain.com/device/000aaa1234cd/dev-prof
Content-Length: ...
Content-Type: application/sip-ua-device-config Changed the name of the event package from sip-config to sip-profile
Content-ID: 000aaa1234cd-3254@localdomain.com
Petrie Informational - Expires Aug. 2003 16 Three high level securityapproaches are now specified.
A Framework for SIP Feb. 2003
User Agent Configuration
The following is an example response from the UA for the above 9.2 Changes from draft-petrie-sipping-config-framework-00.txt
request.
UA => Config. Server Changed name to reflect SIPPING work group item
SIP/2.0 200 Ok Synchronized with changes to SIP DHCP [RFC3361], SIP [RFC3261] and
To: sip:sipuaconfig@sipuaconfig.localdomain.com;tag=owiu1234 [RFC3263], SIP Events [RFC3265] and content indirection
From: sip:000aaa1234cd@localdomain.com;tag=aslkjhd [I-D.ietf-sip-content-indirect-mech]
Call-Id: 987654321@10.1.1.123
Cseq: 22 NOTIFY
Content-Length: 0
Assume at some later time, an administrator makes a change to the Moved the device identity parameters from the From field parameters
content of the sip-config configuration data profile for the UA. to User-Agent header parameters.
The configuration server sends a NOTIFY request to the UA for the
configuration change notification. This example request below
indicates the changed URL or content in the request body with a
higher sequence number.
Config. Server => UA Many thanks to Rich Schaaf of Pingtel, Cullen Jennings of Cisco and
Adam Roach of Dyamicsoft for the great comments and input.
NOTIFY sip:10.1.1.123 SIP/2.0 9.3 Changes from draft-petrie-sip-config-framework-01.txt
To: sip:sipuaconfig@sipuaconfig.localdomain.com;tag=owiu1234
From: sip:000aaa1234cd@localdomain.com;tag=aslkjhd
Call-Id: 987654321@10.1.1.123
Event: sip-config
Cseq: 23 NOTIFY
Content-Type: message/external-body;ACCESS-TYPE=URL;
URL="http://config.localdomain.com/device/000aaa1234cd/dev-prof
Content-Length: ...
Content-Type: application/sip-ua-device-config Changed the name as this belongs in the SIPPING work group.
Content-ID: 000aaa1234cd-3255@localdomain.com
The following is an example response to the above request. Minor edits
UA => Config. Server 9.4 Changes from draft-petrie-sip-config-framework-00.txt
SIP/2.0 200 Ok Many thanks to those who contributed and commented on the previous
To: sip:sipuaconfig@sipuaconfig.localdomain.com;tag=owiu1234 draft. Detailed comments were provided by Henning Schulzrinne from
From: sip:000aaa1234cd@localdomain.com;tag=aslkjhd Columbia U., Cullen Jennings from Cisco, Rohan Mahy from Cisco, Rich
Call-Id: 987654321@10.1.1.123 Schaaf from Pingtel.
Cseq: 23 NOTIFY
Content-Length: 0
9 Security Considerations Split the enrollment into a single SUBSCRIBE dialog for each profile.
The 00 draft sent a single SUBSCRIBE listing all of the desired.
These have been split so that each enrollment can be routed
differently. As there is a concept of device specific and
[This section needs to be greatly expanded and elaborated] user specific profiles, these may also be managed on separate
servers. For instance in a roaming situation the device might get
it's profile data from a local server which knows the LAN specific
profile data. At the same time the user specific profiles might come
from the user's home environment profile delivery server.
SIP basic and digest authentication [6] MAY be used for Removed the Config-Expires header as it is largely superfluous with
SUBSCRIBE/NOTIFY messages used for enrollment and configuration the SUBSCRIBE Expires header.
change notification. There is a chicken and egg problem. Since the
Petrie Informational - Expires Aug. 2003 17 Eliminated some of the complexity in the discovery mechanism.
A Framework for SIP Feb. 2003
User Agent Configuration
content of SUBSCRIBE/NOTIFY messages are transported in the clear, Suggest caching information discovered about a profile delivery
the credentials that the UA uses in the SUBSCRIBE 401 challenge, or server to avoid an avalanche problem when a whole building full of
that the configuration server uses in the NOTIFY 401 challenge must devices powers up.
be provisioned out of band (i.e. user or administrator manual input,
beamed via PDA, smart card, etc.) via a secure means.
Configuration data profile URLs are communicated in the clear in the Added the User-Profile From header field parameter so that the device
NOTIFY requests from the configuration server. The security risk of can a request a user specific profile for a user that is different
unauthorized access of the URL content can be mitigated if the from the device's default user.
configuration server and UA both support basic authentication and
HTTP or HTTPS. There is a chicken and egg problem here as well
since the content of SUBSCRIBE/NOTIFY messages are transported in
the clear. Accordingly,the credentials that the UA uses for the
HTTP/HTTPS GET/POST 401 challenge must be provisioned out of band
(i.e. user or administrator manual input, beamed via PDA, smart
card, etc.) via a secure means.
Using HTTPS over TLS[13] the configuration server MAY request the References
certificate of the UA [14]. If this level of authentication is
desired, the UA vendor SHOULD ship the UA with a digital certificate
or provide a means by which this can be installed out of band. The
configuration server MUST be provisioned with the certificates of
authority allowed for each model of UA to be supported.
Using HTTPS the UA MAY request the certificate of the configuration [I-D.ietf-simple-xcap-package]
server. If this level of authentication is desired the UA must be Rosenberg, J., "A Session Initiation Protocol (SIP) Event
provisioned with the allowed certificate(s) of authority and Package for Modification Events for the Extensible Markup
identities for the configuration server out of band (i.e. user or Language (XML) Configuration Access Protocol (XCAP)
administrator manual input, beamed via PDA, smart card, etc.) via a Managed Documents", draft-ietf-simple-xcap-package-00
secure means. (work in progress), June 2003.
10 Open Issues [I-D.ietf-sip-content-indirect-mech]
Olson, S., "A Mechanism for Content Indirection in Session
Initiation Protocol (SIP) Messages",
draft-ietf-sip-content-indirect-mech-03 (work in
progress), June 2003.
[Do we need an option for the configuration server to tell the UA [I-D.ietf-sipping-ua-prof-framewk-reqs]
that it MUST make the change immediately regardless of state? Petrie, D. and C. Jennings, "Requirements for SIP User
Should this be the default?] Agent Profile Delivery Framework",
draft-ietf-sipping-ua-prof-framewk-reqs-00 (work in
progress), March 2003.
[Upload to configuration server configuration data profiles whole or [I-D.rosenberg-simple-xcap]
changes only ?? define in profiles ??] Rosenberg, J., "The Extensible Markup Language (XML)
Configuration Access Protocol (XCAP)",
draft-rosenberg-simple-xcap-00 (work in progress), May
2003.
[Security considerations section needs much elaboration] [I-D.sinnreich-sipdev-req]
Butcher, I., Lass, S., Petrie, D., Sinnreich, H. and C.
Stredicke, "SIP Telephony Device Requirements,
Configuration and Data", draft-sinnreich-sipdev-req-02
(work in progress), October 2003.
Petrie Informational - Expires Aug. 2003 18 [RFC0822] Crocker, D., "Standard for the format of ARPA Internet
A Framework for SIP Feb. 2003 text messages", STD 11, RFC 822, August 1982.
User Agent Configuration
11 References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[1] R. Droms, "Dynamic host configuration protocol," Request for [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC
Comments (Draft Standard) 2131, Internet Engineering Task Force, 2131, March 1997.
Mar. 1997.
[2] S. Alexander and R. Droms, "DHCP options and BOOTP vendor [RFC2132] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor
extensions," Request for Comments (Draft Standard) 2132, Internet Extensions", RFC 2132, March 1997.
Engineering Task Force, Mar. 1997.
[3] H.Schulzrinne , ˘Dynamic Host Configuration Protocol (DHCP- [RFC2246] Dierks, T., Allen, C., Treese, W., Karlton, P., Freier, A.
for-IPv4)÷, Request for Comments (Draft Standard) 3361, Internet and P. Kocher, "The TLS Protocol Version 1.0", RFC 2246,
Engineering Task Force, Aug. 2002. January 1999.
[4] S. Bradner, "Key words for use in RFCs to indicate [RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
requirement levels," Request for Comments (Best Current Practice) Masinter, L., Leach, P. and T. Berners-Lee, "Hypertext
2119, Internet Engineering Task Force, Mar. 1997. Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
[5] A. Gulbrandsen, P. Vixie, and L. Esibov, ˘A DNS RR for [RFC2617] Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S.,
specifying the location of services (DNS SRV),÷ Request for Leach, P., Luotonen, A. and L. Stewart, "HTTP
Comments 2782, Internet Engineering Task Force, Feb. 2000. Authentication: Basic and Digest Access Authentication",
RFC 2617, June 1999.
[6] Rosenberg, et. al., ˘SIP: session initiation protocol,÷ [RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000.
Request for Comments 3261, Internet Engineering Task Force, June
2002
[7] A. Roach, ˘Event Notification in SIP÷, Request for Comments [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
3265, Internet Engineering Task Force, June 2002 A., Peterson, J., Sparks, R., Handley, M. and E. Schooler,
"SIP: Session Initiation Protocol", RFC 3261, June 2002.
[8] D. Crocker, ˘STANDARD FOR THE FORMAT OF ARPA INTERNET TEXT [RFC3263] Rosenberg, J. and H. Schulzrinne, "Session Initiation
MESSAGES÷, Request for Comments 822, Internet Engineering Task Protocol (SIP): Locating SIP Servers", RFC 3263, June
Force, Aug. 1982 2002.
[9] K. Sollins, ˘THE TFTP PROTOCOL (REVISION 2)÷, Request for [RFC3265] Roach, A., "Session Initiation Protocol (SIP)-Specific
Comments 1350, Internet Engineering Task Force, Jul. 1992 Event Notification", RFC 3265, June 2002.
[10] H Schulzrinne, ˘Configuring IP Telephony End Systems÷, [RFC3361] Schulzrinne, H., "Dynamic Host Configuration Protocol
<schulzrinne-sip-config-00.txt>, IETF; Dec. 2000, Work in (DHCP-for-IPv4) Option for Session Initiation Protocol
progress (SIP) Servers", RFC 3361, August 2002.
[11] D. Petrie, ˘Requirements for a SIP User Agent Configuration [RFC3377] Hodges, J. and R. Morgan, "Lightweight Directory Access
Framework÷, <draft-ietf-sip-config-framewk-reqs-00.txt>, IETF; Protocol (v3): Technical Specification", RFC 3377,
Feb. 2003, Work in progress September 2002.
[12] T. Berners-Lee et al, ˘Uniform Resource Locators (URL)÷, [RFC3617] Lear, E., "Uniform Resource Identifier (URI) Scheme and
Request for Comments 1738, Internet Engineering Task Force, Dec. Applicability Statement for the Trivial File Transfer
1994 Protocol (TFTP)", RFC 3617, October 2003.
[13] E. Rescorla, ˘HTTP Over TLS÷, Request for Comments 2818, Author's Address
Internet Engineering Task Force, May 2000
Petrie Informational - Expires Aug. 2003 19 Daniel Petrie
A Framework for SIP Feb. 2003 Pingtel Corp.
User Agent Configuration 400 W. Cummings Park
Suite 2200
Woburn, MA 01801
US
[14] T. Dierks, C. Allen, ˘The TLS Protocol Version 1.0÷, Request Phone: "Dan Petrie (+1 781 970 0111)"<sip:dpetrie@pingtel.com>
for Comments 2246, Internet Engineering Task Force, Jan. 1999 EMail: dpetrie@pingtel.com
URI: http://www.pingtel.com/
[15] S. Olson ˘A Mechanism for Content Indirection in Session Appendix A. Acknowledgments
Initiation Protocol (SIP) Messages÷, <draft-ietf-sip-content-
indirect-mech-01>, IETF; Nov. 2002, Work in progress
[16] H. Sinnreich, ˘SIP Telephony Device Requirements, Intellectual Property Statement
Configuration and Data÷, <draft-sinnreich-sipdev-req-00.txt>,
IETF; Nov. 2002, Work in progress
[10] H Schulzrinne, ˘Configuring IP Telephony End Systems÷, The IETF takes no position regarding the validity or scope of any
<schulzrinne-sip-config-00.txt>, IETF; Dec. 2000, Work in intellectual property or other rights that might be claimed to
progress pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; neither does it represent that it
has made any effort to identify any such rights. Information on the
IETF's procedures with respect to rights in standards-track and
standards-related documentation can be found in BCP-11. Copies of
claims of rights made available for publication and any assurances of
licenses to be made available, or the result of an attempt made to
obtain a general license or permission for the use of such
proprietary rights by implementors or users of this specification can
be obtained from the IETF Secretariat.
[11] D. Petrie, ˘Requirements for a SIP User Agent Configuration The IETF invites any interested party to bring to its attention any
Framework÷, <draft-petrie-sip-config-framewk-reqs-00.txt>, IETF; copyrights, patents or patent applications, or other proprietary
Feb. 2001, Work in progress rights which may cover technology that may be required to practice
this standard. Please address the information to the IETF Executive
Director.
[12] T. Berners-Lee et al, ˘Uniform Resource Locators (URL)÷, The IETF has been notified of intellectual property rights claimed in
Request for Comments 1738, Internet Engineering Task Force, Dec. regard to some or all of the specification contained in this
1994 document. For more information consult the online list of claimed
rights.
[13] E. Rescorla, ˘HTTP Over TLS÷, Request for Comments 2818, Full Copyright Statement
Internet Engineering Task Force, May 2000
[14] T. Dierks, C. Allen, ˘The TLS Protocol Version 1.0÷, Request Copyright (C) The Internet Society (2003). All Rights Reserved.
for Comments 2246, Internet Engineering Task Force, Jan. 1999
[15] S. Olson ˘A Mechanism for Content Indirection in Session This document and translations of it may be copied and furnished to
Initiation Protocol (SIP) Messages÷, <draft-ietf-sip-content- others, and derivative works that comment on or otherwise explain it
indirect-mech-01>, IETF; Nov. 2002, Work in progress or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than
English.
12 Author's Address The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assignees.
Dan Petrie This document and the information contained herein is provided on an
Pingtel Corp. "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
400 W. Cummings Park Phone: +1 781 938 5306 TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
Woburn, MA USA Email: dpetrie@pingtel.com BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Petrie Informational - Expires Aug. 2003 20 Acknowledgment
Funding for the RFC Editor function is currently provided by the
Internet Society.
 End of changes. 

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