draft-ietf-mediactrl-sip-control-framework-01.txt   draft-ietf-mediactrl-sip-control-framework-02.txt 
Network Working Group C. Boulton Network Working Group C. Boulton
Internet-Draft Avaya Internet-Draft Avaya
Expires: August 25, 2008 T. Melanchuk Expires: October 27, 2008 T. Melanchuk
Rain Willow Communications Rain Willow Communications
S. McGlashan S. McGlashan
Hewlett-Packard Hewlett-Packard
February 22, 2008 April 25, 2008
Media Control Channel Framework Media Control Channel Framework
draft-ietf-mediactrl-sip-control-framework-01 draft-ietf-mediactrl-sip-control-framework-02
Status of this Memo Status of this Memo
By submitting this Internet-Draft, each author represents that any By submitting this Internet-Draft, each author represents that any
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have been or will be disclosed, and any of which he or she becomes have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79. aware will be disclosed, in accordance with Section 6 of BCP 79.
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skipping to change at page 1, line 37 skipping to change at page 1, line 37
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This Internet-Draft will expire on August 25, 2008. This Internet-Draft will expire on October 27, 2008.
Copyright Notice
Copyright (C) The IETF Trust (2008).
Abstract Abstract
This document describes a Framework and protocol for application This document describes a Framework and protocol for application
deployment where the application logic and processing are deployment where the application logic and processing are
distributed. The framework uses the Session Initiation Protocol distributed. The framework uses the Session Initiation Protocol
(SIP) to establish an application-level control mechanism between (SIP) to establish an application-level control mechanism between
application servers and associated external servers such as media application servers and associated external servers such as media
servers. servers.
skipping to change at page 2, line 18 skipping to change at page 2, line 14
centralized conference system, as defined by the IETF. It is not, centralized conference system, as defined by the IETF. It is not,
however, limited to this scope and it is envisioned that this generic however, limited to this scope and it is envisioned that this generic
Framework will be used for a wide variety of de-coupled control Framework will be used for a wide variety of de-coupled control
architectures between network entities. architectures between network entities.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Conventions and Terminology . . . . . . . . . . . . . . . . . 4 2. Conventions and Terminology . . . . . . . . . . . . . . . . . 4
3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4. Control Client SIP UAC Behavior - Control Channel Setup . . . 9 4. Control Channel Setup . . . . . . . . . . . . . . . . . . . . 10
4.1. Control Client SIP UAC Behavior - Media Dialogs . . . . . 12 4.1. Control Client SIP UAC Behavior . . . . . . . . . . . . . 10
5. Control Server SIP UAS Behavior - Control Channel Setup . . . 13 4.2. Control Server SIP UAS Behavior . . . . . . . . . . . . . 12
5. Establishing Media Streams - Control Client SIP UAC
Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
6. Control Framework Interactions . . . . . . . . . . . . . . . . 14 6. Control Framework Interactions . . . . . . . . . . . . . . . . 14
6.1. Constructing Requests . . . . . . . . . . . . . . . . . . 15 6.1. General Behaviour for Constructing Requests . . . . . . . 15
6.1.1. Sending CONTROL . . . . . . . . . . . . . . . . . . . 16 6.2. General Behaviour for Constructing Responses . . . . . . . 16
6.1.2. Sending REPORT . . . . . . . . . . . . . . . . . . . . 16 6.3. Transaction Processing . . . . . . . . . . . . . . . . . . 17
6.1.3. Control Channel Keep-Alive . . . . . . . . . . . . . . 18 6.3.1. CONTROL Transactions . . . . . . . . . . . . . . . . . 17
6.1.4. Package Negotiation . . . . . . . . . . . . . . . . . 21 6.3.2. REPORT Transactions . . . . . . . . . . . . . . . . . 18
6.2. Constructing Responses . . . . . . . . . . . . . . . . . . 22 6.3.3. K-ALIVE Transactions . . . . . . . . . . . . . . . . . 19
6.3.4. SYNC Transactions . . . . . . . . . . . . . . . . . . 21
7. Response Code Descriptions . . . . . . . . . . . . . . . . . . 23 7. Response Code Descriptions . . . . . . . . . . . . . . . . . . 23
7.1. 200 Response Code . . . . . . . . . . . . . . . . . . . . 23 7.1. 200 Response Code . . . . . . . . . . . . . . . . . . . . 23
7.2. 202 Response Code . . . . . . . . . . . . . . . . . . . . 23 7.2. 202 Response Code . . . . . . . . . . . . . . . . . . . . 23
7.3. 400 Response Code . . . . . . . . . . . . . . . . . . . . 23 7.3. 400 Response Code . . . . . . . . . . . . . . . . . . . . 23
7.4. 403 Response Code . . . . . . . . . . . . . . . . . . . . 23 7.4. 403 Response Code . . . . . . . . . . . . . . . . . . . . 23
7.5. 405 Response Code . . . . . . . . . . . . . . . . . . . . 23 7.5. 405 Response Code . . . . . . . . . . . . . . . . . . . . 23
7.6. 420 Response Code . . . . . . . . . . . . . . . . . . . . 23 7.6. 420 Response Code . . . . . . . . . . . . . . . . . . . . 24
7.7. 421 Response Code . . . . . . . . . . . . . . . . . . . . 24 7.7. 421 Response Code . . . . . . . . . . . . . . . . . . . . 24
7.8. 422 Response Code . . . . . . . . . . . . . . . . . . . . 24 7.8. 422 Response Code . . . . . . . . . . . . . . . . . . . . 24
7.9. 423 Response Code . . . . . . . . . . . . . . . . . . . . 24 7.9. 423 Response Code . . . . . . . . . . . . . . . . . . . . 24
7.10. 481 Response Code . . . . . . . . . . . . . . . . . . . . 24 7.10. 481 Response Code . . . . . . . . . . . . . . . . . . . . 24
7.11. 500 Response Code . . . . . . . . . . . . . . . . . . . . 24 7.11. 500 Response Code . . . . . . . . . . . . . . . . . . . . 24
8. Control Packages . . . . . . . . . . . . . . . . . . . . . . . 24 8. Control Packages . . . . . . . . . . . . . . . . . . . . . . . 24
8.1. Control Package Name . . . . . . . . . . . . . . . . . . . 24 8.1. Control Package Name . . . . . . . . . . . . . . . . . . . 25
8.2. Framework Message Usage . . . . . . . . . . . . . . . . . 25 8.2. Framework Message Usage . . . . . . . . . . . . . . . . . 25
8.3. Common XML Support . . . . . . . . . . . . . . . . . . . . 25 8.3. Common XML Support . . . . . . . . . . . . . . . . . . . . 25
8.4. CONTROL Message Bodies . . . . . . . . . . . . . . . . . . 25 8.4. CONTROL Message Bodies . . . . . . . . . . . . . . . . . . 25
8.5. REPORT Message Bodies . . . . . . . . . . . . . . . . . . 25 8.5. REPORT Message Bodies . . . . . . . . . . . . . . . . . . 25
8.6. Audit . . . . . . . . . . . . . . . . . . . . . . . . . . 26 8.6. Audit . . . . . . . . . . . . . . . . . . . . . . . . . . 26
8.7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . 26 8.7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . 26
9. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . . 26 9. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . . 26
9.1. Control Framework Formal Syntax . . . . . . . . . . . . . 26 9.1. Control Framework Formal Syntax . . . . . . . . . . . . . 26
10. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 9.2. Control Framework Dialog Identifier SDP Attribute . . . . 29
10. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
11. Security Considerations . . . . . . . . . . . . . . . . . . . 34 11. Security Considerations . . . . . . . . . . . . . . . . . . . 34
11.1. Session Establishment . . . . . . . . . . . . . . . . . . 34 11.1. Session Establishment . . . . . . . . . . . . . . . . . . 35
11.2. Transport Level Protection . . . . . . . . . . . . . . . . 34 11.2. Transport Level Protection . . . . . . . . . . . . . . . . 35
11.3. Control Channel Policy Management . . . . . . . . . . . . 35 11.3. Control Channel Policy Management . . . . . . . . . . . . 35
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 36 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 36
12.1. Control Packages Registration Information . . . . . . . . 36 12.1. Control Packages Registration Information . . . . . . . . 36
12.1.1. Control Package Registration Template . . . . . . . . 37 12.1.1. Control Package Registration Template . . . . . . . . 37
12.2. Control Framework Method Names . . . . . . . . . . . . . . 37 12.2. Control Framework Method Names . . . . . . . . . . . . . . 37
12.3. Control Framework Status Codes . . . . . . . . . . . . . . 37 12.3. Control Framework Status Codes . . . . . . . . . . . . . . 37
12.4. Control Framework Header Fields . . . . . . . . . . . . . 38 12.4. Control Framework Header Fields . . . . . . . . . . . . . 38
12.5. Control Framework Port . . . . . . . . . . . . . . . . . . 38 12.5. Control Framework Port . . . . . . . . . . . . . . . . . . 38
12.6. SDP Transport Protocol . . . . . . . . . . . . . . . . . . 38 12.6. SDP Transport Protocol . . . . . . . . . . . . . . . . . . 38
13. Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 13. SDP Transport Protocol . . . . . . . . . . . . . . . . . . . . 39
13.1. Changes from 00 Version . . . . . . . . . . . . . . . . . 39 14. Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
14. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 39 14.1. Changes from 01 Version . . . . . . . . . . . . . . . . . 39
15. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 39 14.2. Changes from 00 Version . . . . . . . . . . . . . . . . . 40
16. Appendix A . . . . . . . . . . . . . . . . . . . . . . . . . . 40 15. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 40
16.1. Common Dialog/Multiparty Reference Schema . . . . . . . . 40 16. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 40
17. Normative References . . . . . . . . . . . . . . . . . . . . . 41 17. Appendix A . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 43 17.1. Common Dialog/Multiparty Reference Schema . . . . . . . . 41
Intellectual Property and Copyright Statements . . . . . . . . . . 44 18. Normative References . . . . . . . . . . . . . . . . . . . . . 43
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 44
Intellectual Property and Copyright Statements . . . . . . . . . . 46
1. Introduction 1. Introduction
Real-time media applications are often developed using an Real-time media applications are often developed using an
architecture where the application logic and processing activities architecture where the application logic and processing activities
are distributed. Commonly, the application logic runs on are distributed. Commonly, the application logic runs on
"application servers" whilst the processing runs on external servers, "application servers" but the processing runs on external servers,
such as "media servers". This document focuses on the framework and such as "media servers". This document focuses on the framework and
protocol between the application server and external processing protocol between the application server and external processing
server. The motivation for this framework comes from a set of server. The motivation for this framework comes from a set of
requirements for Media Server Control, which can be found in the requirements for Media Server Control, which can be found in the
'Media Server Control Protocol Requirements' document[8]. While the 'Media Server Control Protocol Requirements' document[RFC5167].
Framework is not media server control specific, it is the primary While the Framework is not media server control specific, it is the
driver and use case for this work. It is intended that the framework primary driver and use case for this work. It is intended that the
contained in this document will be used for a plethora of appropriate framework contained in this document will be applicable for a variety
device control scenarios. of device control scenarios.
This document does not define a SIP based extension that can be used This document does not define a SIP based extension that can be used
directly for the control of external components. The framework directly for the control of external components. The framework
mechanism must be extended by other documents that are known as mechanism must be extended by other documents that are known as
"Control Packages". A comprehensive set of guidelines for creating "Control Packages". A comprehensive set of guidelines for creating
"Control Packages" is described in Section 8. "Control Packages" is described in Section 8.
Current IETF device control protocols, such as megaco [7], while Current IETF device control protocols, such as megaco [RFC3525],
excellent for controlling media gateways that bridge separate while excellent for controlling media gateways that bridge separate
networks, are troublesome for supporting media-rich applications in networks, are troublesome for supporting media-rich applications in
SIP networks, because they duplicate many of the functions inherent SIP networks, because they duplicate many of the functions inherent
in SIP. Rather than relying on single protocol session in SIP. Rather than relying on single protocol session
establishment, application developers need to translate between two establishment, application developers need to translate between two
separate mechanisms. separate mechanisms.
Application servers traditionally use SIP third party call control Application servers traditionally use SIP third party call control
RFC 3725 [12] to establish media sessions from SIP user agents to a [RFC3725] to establish media sessions from SIP user agents to a media
media server. SIP, as defined in RFC 3261 [2], also provides the server. SIP [RFC3261], also provides the ideal rendezvous mechanism
ideal rendezvous mechanism for establishing and maintaining control for establishing and maintaining control connections to external
connections to external server components. The control connections server components. The control connections can then be used to
can then be used to exchange explicit command/response interactions exchange explicit command/response interactions that allow for media
that allow for media control and associated command response results. control and associated command response results.
2. Conventions and Terminology 2. Conventions and Terminology
In this document, BCP 14/RFC 2119 [1] defines the key words "MUST", In this document, BCP 14 [RFC2119] defines the key words "MUST",
"MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT",
"RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL". In "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL". In
addition, BCP 15 indicates requirement levels for compliant addition, BCP 15 indicates requirement levels for compliant
implementations. implementations.
The following additional terms are defined for use in this document: The following additional terms are defined for use in this document:
B2BUA: A B2BUA is a Back-to-Back SIP User Agent. B2BUA: A B2BUA is a Back-to-Back SIP User Agent.
Control Server: A Control Server is an entity that performs a Control Server: A Control Server is an entity that performs a
service, such as media processing, on behalf of a Control Client. service, such as media processing, on behalf of a Control Client.
For example, a media server offers mixing, announcement, tone For example, a media server offers mixing, announcement, tone
detection and generation, and play and record services. The detection and generation, and play and record services. The
Control Server in this case, has a direct RTP [15] relationship Control Server in this case, has a direct RTP [RFC3550]
with the source or sink of the media flow. In this document, we relationship with the source or sink of the media flow. In this
often refer to the Control Server simply as "the Server". document, we often refer to the Control Server simply as "the
Server".
Control Client: A Control Client is an entity that requests Control Client: A Control Client is an entity that requests
processing from a Control Server. Note that the Control Client processing from a Control Server. Note that the Control Client
may not have any processing capabilities whatsoever. For example, may not have any processing capabilities whatsoever. For example,
the Control Client may be an Application Server (B2BUA) or other the Control Client may be an Application Server (B2BUA) or other
endpoint requesting manipulation of a third-party's media stream, endpoint requesting manipulation of a third-party's media stream,
that terminates on a media server acting in the role of a Control that terminates on a media server acting in the role of a Control
Server. In this document, we often refer to the Control Client Server. In this document, we often refer to the Control Client
simply as "the Client". simply as "the Client".
Control Channel: A Control Channel is a reliable connection between Control Channel: A Control Channel is a reliable connection between
a Client and Server that is used to exchange Framework messages. a Client and Server that is used to exchange Framework messages.
The term "Connection" is used synonymously within this document. The term "Connection" is used synonymously within this document.
Framework Message: A Framework Message is a message on a Control Framework Message: A Framework Message is a message on a Control
Channel that has a type corresponding to one of the Methods Channel that has a type corresponding to one of the Methods
defined in this document. A Framework message is often referred defined in this document. A Framework message is often referred
to by its method, such as a "CONTROL message". to by its method, such as a "CONTROL message".
Method: A Method is the type of a framework message. Four Methods Method: A Method is the type of a framework message. Four Methods
are defined in this document: SYNCH, CONTROL, REPORT, and K-ALIVE. are defined in this document: SYNC, CONTROL, REPORT, and K-ALIVE.
Control Command: A Control Command is an application level request Control Command: A Control Command is an application level request
from a Client to a Server. Control Commands are carried in the from a Client to a Server. Control Commands are carried in the
body of CONTROL messages. Control Commands are defined in body of CONTROL messages. Control Commands are defined in
separate specifications known as "Control Packages". separate specifications known as "Control Packages".
framework transaction: A framework transaction is defined as a framework transaction: A framework transaction is defined as a
sequence composed of a control framework message originated by sequence composed of a control framework message originated by
either a Control Client or Control Server and responded to with a either a Control Client or Control Server and responded to with a
control Framework response code message. Note that the control control Framework response code message. Note that the control
framework has no "provisional" responses. A control framework framework has no "provisional" responses. A control framework
transaction MUST complete within 'Transaction-Timeout' time. transaction MUST complete within 5 seconds and is referenced
throughout the draft as 'Transaction-Timeout'.
extended transaction lifetime: An extended transaction lifetime is extended transaction lifetime: An extended transaction lifetime is
used to extend the lifetime of a CONTROL method transaction when used to extend the lifetime of a CONTROL method transaction when
the Control Command it carries cannot be completed within the Control Command it carries cannot be completed within
Transaction-Timeout milliseconds. A Server extends the lifetime 'Transaction-Timeout'. A Server extends the lifetime of a CONTROL
of a CONTROL method transaction by sending a 202 response code method transaction by sending a 202 response code followed by one
followed by one or more REPORT transactions as specified in or more REPORT transactions as specified in Section 6.3.2.
Section 6.1.2. Extended transaction lifetimes allow command Extended transaction lifetimes allow command failures to be
failures to be discovered at the transaction layer. discovered at the transaction layer.
Transaction-Timeout: the maximum allowed time between a control Transaction-Timeout: the maximum allowed time between a control
Client or Server issuing a framework message and receiving a Client or Server issuing a framework message and receiving a
corresponding response. The value for the timeout should be based corresponding response. The value for the timeout should be based
on a multiple of the network RTT plus 'Transaction-Timeout' on a multiple of the network RTT plus an appropriate number
milliseconds to allow for message parsing and processing. milliseconds to allow for message parsing and processing. The
value for 'Transaction-Timeout' is 5 seconds.
[Editors Note:DP0 - Need to pick a time for "Transaction-Time" - Work
Group input requested.]
3. Overview 3. Overview
This document details mechanisms for establishing, using, and This document details mechanisms for establishing, using, and
terminating a reliable channel using SIP for the purpose of terminating a reliable channel using SIP for the purpose of
controlling an external server. The following text provides a non- controlling an external server. The following text provides a non-
normative overview of the mechanisms used. Detailed, normative normative overview of the mechanisms used. Detailed, normative
guidelines are provided later in the document. guidelines are provided later in the document.
Control channels are negotiated using standard SIP mechanisms that Control channels are negotiated using standard SIP mechanisms that
would be used in a similar manner to creating a SIP multimedia would be used in a similar manner to creating a SIP multimedia
session. Figure 1 illustrates a simplified view of the proposed session. Figure 1 illustrates a simplified view of the mechanism.
mechanism. It highlights a separation of the SIP signaling traffic It highlights a separation of the SIP signaling traffic and the
and the associated control channel that is established as a result of associated control channel that is established as a result of the SIP
the SIP interactions. interactions.
The use of SIP for the specified mechanism provides many inherent The use of SIP for to negotiate the control-channel provides many
capabilities which include:- inherent capabilities which include:
o Service location - Use SIP Proxies or Back-to-Back User Agents for o Service location - Use SIP Proxies or Back-to-Back User Agents for
discovering Control Servers. discovering Control Servers.
o Security mechanisms - Leverage established security mechanisms o Security mechanisms - Leverage established security mechanisms
such as Transport Layer Security (TLS) and Client Authentication. such as Transport Layer Security (TLS) and Client Authentication.
o Connection maintenance - The ability to re-negotiate a connection, o Connection maintenance - The ability to re-negotiate a connection,
ensure it is active, audit parameters, and so forth. ensure it is active, audit parameters, and so forth.
o Application agnostic - Generic protocol allows for easy extension. o Application agnostic - Generic protocol allows for easy extension.
As mentioned in the previous list, one of the main benefits of using As mentioned in the previous list, one of the main benefits of using
SIP as the session control protocol is the "Service Location" SIP as the session control protocol is the "Service Location"
facilities provided. This applies at both a routing level, where RFC facilities provided. This applies at both a routing level, where
3263 [4] provides the physical location of devices, and at the [RFC3263] provides the physical location of devices, and at the
Service level, using Caller Preferences[13] and Callee Service level, using Caller Preferences [RFC3840] and Callee
Capabilities[14]. The ability to select a Control Server based on Capabilities [RFC3841]. The ability to select a Control Server based
Service level capabilities is extremely powerful when considering a on Service level capabilities is extremely powerful when considering
distributed, clustered architecture containing varying services (for a distributed, clustered architecture containing varying services
example Voice, Video, IM). More detail on locating Control Server (for example Voice, Video, IM). More detail on locating Control
resources using these techniques is outlined in Section 4 of this Server resources using these techniques is outlined in Section 4.1 of
document. this document.
+--------------SIP Traffic--------------+ +--------------SIP Traffic--------------+
| | | |
v v v v
+-----+ +--+--+ +-----+ +--+--+
| SIP | | SIP | | SIP | | SIP |
|Stack| |Stack| |Stack| |Stack|
+---+-----+---+ +---+-----+---+ +---+-----+---+ +---+-----+---+
| Control | | Control | | Control | | Control |
| Client |<----Control Channel---->| Server | | Client |<----Control Channel---->| Server |
skipping to change at page 7, line 27 skipping to change at page 7, line 27
The example from Figure 1 conveys a 1:1 connection between the The example from Figure 1 conveys a 1:1 connection between the
Control Client and the Control Server. It is possible, if required, Control Client and the Control Server. It is possible, if required,
for multiple control channels using separate SIP dialogs to be for multiple control channels using separate SIP dialogs to be
established between the Control Client and the Control Server established between the Control Client and the Control Server
entities. Any of the connections created between the two entities entities. Any of the connections created between the two entities
can then be used for Server control interactions. The control can then be used for Server control interactions. The control
connections are agnostic to any media sessions. Specific media connections are agnostic to any media sessions. Specific media
session information can be incorporated in control interaction session information can be incorporated in control interaction
commands (which themselves are defined in external packages) using commands (which themselves are defined in external packages) using
the XML schema defined in Section 16. The ability to have multiple the XML schema defined in Section 17. The ability to have multiple
control channels allows for stronger redundancy and the ability to control channels allows for stronger redundancy and the ability to
manage high volumes of traffic in busy systems. manage high volumes of traffic in busy systems.
Consider the following simple example for session establishment Consider the following simple example for session establishment
between a Client and a Server (Note: Some lines in the examples are between a Client and a Server (Note: Some lines in the examples are
removed for clarity and brevity). Note that the roles discussed are removed for clarity and brevity). Note that the roles discussed are
logical and can change during a session, if the Control Package logical and can change during a session, if the Control Package
allows. allows.
The Client constructs and sends a standard SIP INVITE request, as The Client constructs and sends a standard SIP INVITE request, as
defined in RFC 3261 [2], to the external Server. The SDP payload defined in [RFC3261], to the external Server. The SDP payload
includes the required information for control channel negotiation and includes the required information for control channel negotiation and
is the primary mechanism for conveying support for this specification is the primary mechanism for conveying support for this specification
(through the media type). The COMEDIA [6] specification for setting (through the media type). The COMEDIA [RFC4145] specification for
up and maintaining reliable connections is used as part of the setting up and maintaining reliable connections is used as part of
negotiation mechanism (more detail available in later sections). the negotiation mechanism (more detail available in later sections).
The Client will also include the 'cfw-id' SDP attribute, as defined
in this specification which is used to correlate the underlying Media
Control Channel with the offer/answer exchange.
Client Sends to External Server: Client Sends to External Server:
INVITE sip:External-Server@example.com SIP/2.0 INVITE sip:External-Server@example.com SIP/2.0
To: <sip:External-Server@example.com> To: <sip:External-Server@example.com>
From: <sip:Client@example.com>;tag=64823746 From: <sip:Client@example.com>;tag=64823746
Via: SIP/2.0/UDP client.example.com;branch=z9hG4bK72dhjsU Via: SIP/2.0/UDP client.example.com;branch=z9hG4bK72dhjsU
Call-ID: 7823987HJHG6 Call-ID: 7823987HJHG6
CSeq: 1 INVITE CSeq: 1 INVITE
Contact: <sip:Client@clientmachine.example.com> Contact: <sip:Client@clientmachine.example.com>
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: [..] Content-Length: [..]
v=0 v=0
o=originator 2890844526 2890842808 IN IP4 controller.example,com o=originator 2890844526 2890842808 IN IP4 controller.example,com
s=- s=-
c=IN IP4 controller.example.com c=IN IP4 controller.example.com
m=application 7575 TCP/SCFW m=application 7575 TCP/CFW
a=setup:active a=setup:active
a=connection:new a=connection:new
a=cfw-id:H839quwhjdhegvdga
On receiving the INVITE request, the external Server supporting this On receiving the INVITE request, an external Server supporting this
mechanism generates a 200 OK response containing appropriate SDP. mechanism generates a 200 OK response containing appropriate SDP.
The 'cfw-id' SDP attribute is copied from the original offer.
External Server Sends to Client: External Server Sends to Client:
SIP/2.0 200 OK SIP/2.0 200 OK
To: <sip:External-Server@example.com>;tag=28943879 To: <sip:External-Server@example.com>;tag=28943879
From: <sip:Client@example.com>;tag=64823746 From: <sip:Client@example.com>;tag=64823746
Via: SIP/2.0/UDP client.example.com;branch=z9hG4bK72dhjsU Via: SIP/2.0/UDP client.example.com;branch=z9hG4bK72dhjsU
Call-ID: 7823987HJHG6 Call-ID: 7823987HJHG6
CSeq: 1 INVITE CSeq: 1 INVITE
Contact: <sip:External-Server@servermachine.example.com> Contact: <sip:External-Server@servermachine.example.com>
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: [..] Content-Length: [..]
v=0 v=0
o=originator 2890844526 2890842808 IN IP4 server.example.com o=originator 2890844526 2890842808 IN IP4 server.example.com
s=- s=-
c=IN IP4 mserver.example.com c=IN IP4 mserver.example.com
m=application 7563 TCP/SCFW m=application 7563 TCP/CFW
a=setup:passive a=setup:passive
a=connection:new a=connection:new
a=cfw-id:H839quwhjdhegvdga
The Control Client receives the SIP 200 OK response and extracts the The Control Client receives the SIP 200 OK response and extracts the
relevant information (also sending a SIP ACK). It creates an relevant information (also sending a SIP ACK). It creates an
outgoing (as specified by the SDP 'setup:' attribute of 'active') TCP outgoing (as specified by the SDP 'setup:' attribute of 'active') TCP
connection to the Control Server. The connection address (taken from connection to the Control Server. The connection address (taken from
'c=') and port (taken from 'm=')are used to identify the remote part 'c=') and port (taken from 'm=')are used to identify the remote port
in the new connection. in the new connection.
Once established, the newly created connection can be used to Once established, the newly created connection can be used to
exchange control language request and response primitives. If exchange requests and responses as defined in this document. If
required, after the control channel has been setup, media sessions required, after the control channel has been setup, media sessions
can be established using standard SIP third party call control. can be established using standard SIP third party call control.
Figure 4 provides a simplified example where the proposed framework Figure 2 provides a simplified example where the framework is used to
is used to control a User Agent's RTP session. (1) in brackets control a User Agent's RTP session. (1) in brackets represents the
represents the SIP dialog and dedicated control channel previously SIP dialog and dedicated control channel previously described in this
described in this overview section. overview section.
+--------Control SIP Dialog(1)---------+ +--------Control SIP Dialog(1)---------+
| | | |
v v v v
+-----+ +--+--+ +-----+ +--+--+
+------(2)------>| SIP |---------------(2)------------->| SIP | +------(2)------>| SIP |---------------(2)------------->| SIP |
| |Stack| |Stack| | |Stack| |Stack|
| +---+-----+---+ +---+-----+---+ | +---+-----+---+ +---+-----+---+
| | | | | | | | | |
| | Control |<--Control Channel(1)-->| | | | Control |<--Control Channel(1)-->| |
| | Client | | Control | | | Client | | Control |
| +-------------+ | Server | | +-------------+ | Server |
+--+--+ | | +--+--+ | |
|User | | | |User | | |
|Agent|<=====================RTP(2)===================>| | |Agent|<=====================RTP(2)===================>| |
+-----+ +-------------+ +-----+ +-------------+
Figure 4: Participant Architecture Figure 2: Participant Architecture
(2) from Figure 4 represents the User Agent SIP dialog interactions (2) from Figure 2 represents the User Agent SIP dialog interactions
and associated media flow. A User Agent would create a SIP dialog and associated media flow. A User Agent would create a SIP dialog
with the Control Client entity. The Control Client entity will also with the Control Client entity. The Control Client entity will also
create a related dialog to the Control Server (B2BUA type create a related dialog to the Control Server (B2BUA type
functionality). Using the interaction illustrated by (2), the User functionality). Using the interaction illustrated by (2), the
Agent is able to negotiate media capabilities with the Control Server Control Client negotiates media capabilities with the Control Server,
using standard SIP mechanisms as defined in RFC 3261 [2] and RFC 3264 on behalf of the User Agent, using SIP Third Party Call Control
[5]. [RFC3725].
4. Control Client SIP UAC Behavior - Control Channel Setup 4. Control Channel Setup
4.1. Control Client SIP UAC Behavior
On creating a new SIP INVITE request for control channel setup, a UAC On creating a new SIP INVITE request for control channel setup, a UAC
MUST construct the protocol message as defined in RFC 3261 [2]. MUST construct the protocol message as defined in [RFC3261].
If a reliable response is received (as defined RFC 3261 [2] and RFC If a reliable response is received (as defined [RFC3261] and
3262 [3]), the mechanisms defined in this document are applicable to [RFC3262]), the mechanisms defined in this document are applicable to
the newly created dialog. the newly created dialog.
The UAC MAY include a valid session description (an 'offer' as The UAC MAY include a valid session description (an 'offer' as
defined in RFC 3264 [5]) in an INVITE request using the Session defined in [RFC3264]) in an INVITE request using the Session
Description Protocol defined in [9]. The following information Description Protocol defined in [RFC4566] (*note - SIP also allows an
defines the composition of some specific elements of the SDP payload 'offer-less' INVITE which is also maintained by this specification).
that MUST be adhered to for compliancy to this specification when The following information defines the composition of some specific
used in an SIP SDP offer. elements of the SDP payload that MUST be adhered to for compliancy to
this specification when used in an SIP SDP offer.
The Connection Data line in the SDP payload is constructed as The Connection Data line in the SDP payload is constructed as
specified in [9]: specified in [RFC4566]:
c=<nettype> <addrtype> <connection-address> c=<nettype> <addrtype> <connection-address>
The first sub-field, <nettype>, MUST equal the value "IN". The The first sub-field, <nettype>, MUST equal the value "IN". The
second sub-field, <addrtype>, MUST equal either "IP4" or "IP6". The second sub-field, <addrtype>, MUST equal either "IP4" or "IP6". The
third sub-field for Connection Data is <connection-address>. This third sub-field for Connection Data is <connection-address>. This
supplies a representation of the SDP originators address, for example supplies a representation of the SDP originators address, for example
dns/IP representation. The address will be the network address used dns/IP representation. The address will be the network address used
for connections in this specification. for connections in this specification.
skipping to change at page 10, line 45 skipping to change at page 11, line 4
m=<media> <port> <proto> m=<media> <port> <proto>
The first "sub-field" <media> MUST equal the value "application". The first "sub-field" <media> MUST equal the value "application".
The second sub-field, <port>, MUST represent a port on which the The second sub-field, <port>, MUST represent a port on which the
constructing client can receive an incoming connection if required. constructing client can receive an incoming connection if required.
The port is used in combination with the address specified in the The port is used in combination with the address specified in the
'Connection Data line defined previously to supply connection 'Connection Data line defined previously to supply connection
details. If the constructing client can't receive incoming details. If the constructing client can't receive incoming
connections it MUST still enter a valid port range entry. The use of connections it MUST still enter a valid port range entry. The use of
the port value '0' has the same meaning as defined in the SDP the port value '0' has the same meaning as defined in the SDP
specification[9]. The third sub-field, <proto>, MUST equal a specification[RFC4566]. The Control Framework has an IANA-registered
recommended port defined in Section 12.5. This value is not a
default as a client is free to choose explicit port numbers.
However, SDP SHOULD be configured so that the recommended port is
used whenever appropriate. This makes life easier for network
administrators who need to manage firewall policy for Control
Framework interactions. The third sub-field, <proto>, MUST equal a
transport value defined in Section 12.6. All implementations transport value defined in Section 12.6. All implementations
compliant to this specification MUST support the value "TCP/SCFW", compliant to this specification MUST support the value "TCP/CFW",
"TCP/TLS/SCFW", "SCTP/SCFW" and "SCTP/TLS/SCFW" as defined in "TCP/TLS/CFW", "SCTP/CFW" and "SCTP/TLS/CFW" as defined in
Section 12.6 of this document. Implementations MUST support TLS as a Section 12.6 of this document. Implementations MUST support TLS as a
transport-level security mechanism, although use of TLS in specific transport-level security mechanism, although use of TLS in specific
deployments is optional. MEDIACTRL implementations MUST support TCP deployments is optional. Control Framework implementations MUST
as a transport protocol. MEDIACTRL implementations MAY support SCTP support TCP as a transport protocol. Control Framework
as a transport protocol. When an entity identifies one of the implementations MAY support SCTP as a transport protocol. When an
transport values defined in Section 12.6 but is not willing to entity identifies one of the transport values defined in Section 12.6
establish the session, it MUST respond using the appropriate SIP but is not willing to establish the session, it MUST respond using
mechanism. the appropriate SIP mechanism.
The SDP MUST also contain a number of SDP media attributes(a=) that The SDP MUST also contain a number of SDP media attributes(a=) that
are specifically defined in the COMEDIA [6] specification. The are specifically defined in the COMEDIA [RFC4145] specification. The
attributes provide connection negotiation and maintenance parameters. attributes provide connection negotiation and maintenance parameters.
A client conforming to this specification SHOULD support all the A client conforming to this specification SHOULD support all the
possible values defined for media attributes from the COMEDIA [6] possible values defined for media attributes from the COMEDIA
specification but MAY choose not to support values if it can [RFC4145] specification but MAY choose not to support values if it
definitely determine they will never be used (for example will only can definitely determine they will never be used (for example will
ever initiate outgoing connections). It is RECOMMENDED that a only ever initiate outgoing connections). It is RECOMMENDED that a
Controlling UAC initiate a connection to an external Server but that Controlling UAC initiate a connection to an external Server but that
an external Server MAY negotiate and initiate a connection using an external Server MAY negotiate and initiate a connection using
COMEDIA, if network topology prohibits initiating connections in a COMEDIA, if network topology prohibits initiating connections in a
certain direction. An example of the attributes is: certain direction. An example of the attributes is:
a=setup:active a=setup:active
a=connection:new a=connection:new
This example demonstrates a new connection that will be initiated This example demonstrates a new connection that will be initiated
from the owner of the SDP payload. The connection details are from the owner of the SDP payload. The connection details are
contained in the SDP answer received from the UAS. A full example of contained in the SDP answer received from the UAS. A full example of
an SDP payload compliant to this specification can be viewed in an SDP payload compliant to this specification can be viewed in
Section 3. Once the SDP has been constructed along with the Section 3. Once the SDP has been constructed along with the
remainder of the SIP INVITE request (as defined in RFC 3261 [2]), it remainder of the SIP INVITE request (as defined in [RFC3261]), it can
can be sent to the appropriate location. The SIP dialog and be sent to the appropriate location. The SIP dialog and appropriate
appropriate control connection is then established. control connection is then established.
As mentioned previously, the SIP Control Framework can be used in A client constructing an offer MUST include the 'cfw-id' SDP
conjunction with other media dialogs (for example, use the control attribute as defined in Section 9.2. The 'cfw-id' attribute
channel to play a prompt to media dialog X). For SIP based media indicates an identifier that can be used used within the control
dialogs, if not present in the SDP received by the Control Client channel to correlate the control channel with this SIP dialog. This
(when acting as a B2BUA) from the User Agent, a media label SDP attribute MUST contain an appropriately random value that will not
attribute, which is defined in RFC 4574 [10], should be inserted for clash with other offer/answer exchanges that will take place and is
every media description (identified as m= line as defined in [9]) globally unique over space and time. The value chosen for the
before forwarding. This provides flexibility for the Control Client 'cfw-id' attribute MUST be used for the entire duration of the
as it can generate control messages using the Control Channel that associated SIP dialog and not be changed during updates to the offer/
specify a particular Media stream (between User Agent and Control answer exchange.
Server) within a SIP media dialog. If a Media label is not included
in the control message, commands apply to all media associated with
the dialog.
A non-2xx class error (4xx, 5xx and 6xx) SIP response received for A non-2xx class error (4xx, 5xx and 6xx) SIP response received for
the INVITE request indicates that no SIP dialog has been created and the INVITE request indicates that no SIP dialog has been created and
is treated as specified RFC 3261 [2]. Specifically, support of this is treated as specified [RFC3261]. Specifically, support of this
specification is negotiated through the presence of the media type specification is negotiated through the presence of the media type
defined in this specification. The receipt of a SIP error response defined in this specification. The receipt of a SIP error response
like "488" indicates that the offer contained in a request is not like "488" indicates that the offer contained in a request is not
acceptable. The inclusion of the media line associated with this acceptable. The inclusion of the media line associated with this
specification in such a rejected offer should indicate to the client specification in such a rejected offer should indicate to the client
generating the offer that this could be due to the receiving client generating the offer that this could be due to the receiving client
not supporting this specification. The client generating the offer not supporting this specification. The client generating the offer
should act as it would normally on receiving this response, as per should act as it would normally on receiving this response, as per
RFC 3261 [2]. Media streams can also be rejected by setting the port [RFC3261]. Media streams can also be rejected by setting the port to
to "0" in the "m=" line of the session description. A client using "0" in the "m=" line of the session description. A client using this
this specification should be prepared to receive an answer where the specification should be prepared to receive an answer where the "m="
"m=" line it inserted for using the Control Framework has been set to line it inserted for using the Control Framework has been set to "0".
"0".
4.1. Control Client SIP UAC Behavior - Media Dialogs
It is intended that the Control framework will be used within a
variety of architectures for a wide range of functions. One of the
primary functions will be the use of the control channel to apply
specific Control package commands to co-existing SIP dialogs that
have been established with the same remote server, for example the
manipulation of audio dialogs connected to a media server.
Such co-existing dialogs will pass through the Control Client (see
Figure 4) entity and may contain more than one Media Description (as
defined by "m=" in the SDP). The Control Client SHOULD include a
media label attribute (B2BUA functionality), as defined in [10], for
each "m=" definition. A Control Client constructing the SDP MAY
choose not to include the media label SDP attribute if it does not
require direct control on a per media stream basis.
This framework identifies the common re-use of referencing media
dialogs and has specified a connection reference attribute that can
optionally be imported into any Control Package. It is intended that
this will reduce repetitive specifying of dialog reference language.
The schema can be found in Section 16.1 in Appendix A.
Similarly, the ability to identify and apply commands to a group of
associated media dialogs (multiparty) is also identified as a common
structure that could be defined and re-used (for example playing a
prompt to all participants in a Conference). The schema for such
operations can also be found in Section 16.1 in Appendix A.
Support for both the common attributes described here is specified as
part of each Control Package definition, as detailed in Section 8.
5. Control Server SIP UAS Behavior - Control Channel Setup 4.2. Control Server SIP UAS Behavior
On receiving a SIP INVITE request, an external Server(UAS) inspects On receiving a SIP INVITE request, an external Server(UAS) inspects
the message for indications of support for the mechanisms defined in the message for indications of support for the mechanisms defined in
this specification. This is achieved through inspection of the this specification. This is achieved through inspection of the
Sessions Description of the SIP INVITE message and identifying Sessions Description of the SIP INVITE message and identifying
support for the appropriate media type. If the external Server support for the appropriate media type. If the external Server
wishes to construct a reliable response that conveys support for the wishes to construct a reliable response that conveys support for the
extension, it should follow the mechanisms defined in RFC 3261 [2]. extension, it should follow the mechanisms defined in [RFC3261]. If
If support is conveyed in a reliable SIP provisional response, the support is conveyed in a reliable SIP provisional response, the
mechanisms in RFC 3262 [3] MUST also be used. It should be noted mechanisms in [RFC3262] MUST also be used. It should be noted that
that the SDP offer is not restricted to the initial INVITE request the SDP offer is not restricted to the initial INVITE request and may
and may appear in any series of messages that are compliant to RFC appear in any series of messages that are compliant to [RFC3261],
3261 [2], RFC 3262 [3], and RFC 3264 [5] [RFC3262], and [RFC3264]
When constructing an answer, the SDP payload MUST be constructed When constructing an answer, the SDP payload MUST be constructed
using the semantics(Connection, Media and attribute) defined in using the semantics(Connection, Media and attribute) defined in
Section 4 using valid local settings and also with full compliance to Section 4.1 using valid local settings and also with full compliance
the COMEDIA[6] specification. For example, the SDP attributes to the COMEDIA[RFC4145] specification. For example, the SDP
included in the answer constructed for the example offer provided in attributes included in the answer constructed for the example offer
Section 4 would look as illustrated below: provided in Section 4.1 would look as illustrated below:
a=setup:passive a=setup:passive
a=connection:new a=connection:new
A client constructing an answer MUST include the 'cfw-id' SDP
attribute as defined in Section 9.2. This attribute MUST copy the
value which appeared in the initial offer.
Once the SIP success response has been constructed, it is sent using Once the SIP success response has been constructed, it is sent using
standard SIP mechanisms. Depending on the contents of the SDP standard SIP mechanisms. Depending on the contents of the SDP
payloads that were negotiated using the Offer/Answer exchange, a payloads that were negotiated using the Offer/Answer exchange, a
reliable connection will be established between the Controlling UAC reliable connection will be established between the Controlling UAC
and external Server UAS entities. The newly established connection and external Server UAS entities. The newly established connection
is now available to exchange control command primitives. The state is now available to exchange control command primitives. The state
of the SIP Dialog and the associated Control channel are now of the SIP Dialog and the associated Control channel are now
implicitly linked. If either party wishes to terminate a Control implicitly linked. If either party wishes to terminate a Control
channel it simply issues a SIP termination request (SIP BYE request). channel it simply issues a SIP termination request (SIP BYE request).
The Control Channel therefore lives for the duration of the SIP The Control Channel therefore lives for the duration of the SIP
dialog. dialog.
If the UAS does not support the extension defined in this document, If the UAS does not support the extension defined in this document,
as identified by the media contained in the Session Description, it as identified by the media contained in the Session Description, it
SHOULD respond as detailed in RFC 3261 [2] with a "SIP 488" response SHOULD respond as detailed in [RFC3261] with a "SIP 488" response
code. If multiple media descriptions exist it MAY choose to continue code. If multiple media descriptions exist it MAY choose to continue
processing the request and mark the port field equal to "0". processing the request and mark the port field equal to "0".
A SIP entity receiving a SIP OPTIONS request MUST respond A SIP entity receiving a SIP OPTIONS request MUST respond
appropriately as defined in RFC 3261 [2]. This involves providing appropriately as defined in [RFC3261]. This involves providing
information relating to supported SIP extensions and media types in a information relating to supported SIP extensions and media types in a
200 OK response. For this extension the media types supported MUST 200 OK response. For this extension the media types supported MUST
be included in the SIP 200 OK response in a SIP "Accept" header to be included in the SIP 200 OK response in a SIP "Accept" header to
indicate a valid media type. indicate a valid media type.
5. Establishing Media Streams - Control Client SIP UAC Behavior
It is intended that the Control framework will be used within a
variety of architectures for a wide range of functions. One of the
primary functions will be the use of the control channel to apply
specific Control package commands to media sessions established by
SIP dialogs (media dialogs) with the same remote server. For
example, to apply a command to generate audio media (such as an
announcement) on an RTP session between a User Agent and a Media
Server.
SIP dialogs used to establish media sessions (see Figure 2) on behalf
of User Agents may contain more than one Media Description (as
defined by "m=" in the SDP). The Control Client SHOULD include a
media label attribute (B2BUA functionality), as defined in [RFC4574],
for each "m=" definition. A Control Client constructing the SDP MAY
choose not to include the media label SDP attribute if it does not
require direct control on a per media stream basis.
This framework identifies the common re-use of referencing media
dialogs and has specified a connection reference attribute that can
optionally be imported into any Control Package. It is intended that
this will reduce repetitive specifying of dialog reference language.
The schema can be found in Section 17.1 in Appendix A.
Similarly, the ability to identify and apply commands to a group of
associated media dialogs (multiparty) is also identified as a common
structure that could be defined and re-used (for example playing a
prompt to all participants in a Conference). The schema for such
operations can also be found in Section 17.1 in Appendix A.
Support for both the common attributes described here is specified as
part of each Control Package definition, as detailed in Section 8.
6. Control Framework Interactions 6. Control Framework Interactions
The use of the COMEDIA specification in this document allows for a The use of the COMEDIA specification in this document allows for a
Control Channel to be set up in either direction as a result of the Control Channel to be set up in either direction as a result of a SIP
SIP INVITE transaction. While providing a flexible negotiation INVITE transaction. SIP provides a flexible negotiation mechanism to
mechanism, it does provide certain correlation problems between the establish the control channel, but there needs to be a mechanism
channel and the overlying SIP dialog. Remember that the two are within the control channel to correlate the control channel with the
implicitly linked and so need a robust correlation mechanism. A SIP dialog used for its establishment. A Control Client receiving an
Control Client receiving an incoming connection (whether it be acting incoming connection (whether it be acting in the role of UAC or UAS)
in the role of UAC or UAS) has no way of identifying the associated has no way of identifying the associated SIP dialog as it could be
SIP dialog as it could be simply listening for all incoming simply listening for all incoming connections on a specific port.
connections on a specific port. As a consequence, some rules are The following steps, which implementations MUST support, allow a
applied to allow a connecting (defined as 'active' role in COMEDIA) connecting UA (defined as 'active' role in COMEDIA) to identify the
active UA to identify the associated SIP dialog that triggered the associated SIP dialog that triggered the connection. These steps
connection. The following steps provide an identification mechanism SHOULD be carried out before any other signaling on the newly created
that MUST be carried out before any other signaling is carried out on Control channel. An alternative dialog association mechanism MAY be
the newly created Control channel. specified in extensions to this document.
o Once the connection has been established, the active UA initiating o Once the connection has been established, the UA acting in the
the connection (as determined by COMEDIA) MUST immediately send a active role (active UA) to initiate the connection MUST
Control Framework SYNCH request. The SYNCH request will be immediately send a Control Framework SYNC request. The SYNC
constructed as defined in Section 9.1 and MUST contain the message request MUST be constructed as defined in Section 9.1 and MUST
header, 'Dialog-ID', which contains the SIP dialog information. contain the message header, 'Dialog-ID', which contains the SIP
o The 'Dialog-ID' message header is constructed by concatenating the dialog information.
Local-tag, Call-ID and Remote-tag (as defined in Section 9.1) from o The 'Dialog-ID' message header value is the value contained in the
the SIP dialog and separating with a '~'. See syntax defined in 'cfw-id' SDP attribute. This allows for a correlation between the
Section 16.1 in Appendix A and examples in Section 8.7. For control channel and its associated SIP dialog.
example, if the SIP dialog had values of 'Local-tag=HKJDH',
'Remote-tag=JJSUSHJ' and 'Call-ID=8shKUHSUKHW@example.com' - the
'Dialog-ID' header would look like this:
'Dialog-ID=HKJDH~8shKUHSUKHW@example.com~JJSUSHJ'.
o On creating the SYNCH request the controlling active UA MUST
follow the procedures outlined in Section 6.1.3 . This provides
details of connection keep-alive messages.
o On creating the SYNCH request the controlling active UA MUST also
follow the procedures outlined in Section 6.1.4. This provides
details of the negotiation mechanism used to determine the
Protocol Data Units (PDUs) that can be exchanged on the
established control channel connection.
o The active UA who initiated the connection MUST then send the
SYNCH request. It MUST then wait for a period of at least 5
seconds to receive a response. It MAY choose a longer time to
wait but it should not be shorter than 5 seconds.
o If no response is received for the SYNCH control message, a o On creating the SYNC request the active UA MUST follow the
timeout occurs and the control channel is terminated along with procedures outlined in Section 6.3.3 . This provides details of
the associated SIP dialog (issue a BYE request). connection keep-alive messages.
o If the active UA who initiated a connection receives a 481 o On creating the SYNC request the active UA MUST also follow the
response, this implies that the SYNCH request was received but no procedures outlined in Section 6.3.4.2. This provides details of
associated SIP dialog exists. This also results in the control the negotiation mechanism used to determine the Protocol Data
channel being terminated along with the associated SIP dialog Units (PDUs) that can be exchanged on the established control
(issue a BYE request). channel connection.
o All other error responses received for the SYNCH request are o The active UA MUST then send the SYNC request. It MUST then wait
for a period of at least 'Transaction-Timeout' to receive a
response. It MAY choose a longer time to wait but it should not
be shorter than 'Transaction-Timeout'.
o If no response is received for the SYNC control message, a timeout
occurs and the control channel is terminated along with the
associated SIP dialog (issue a BYE request).
o If the active UA receives a 481 response, this implies that the
SYNC request was received but no associated SIP dialog exists.
This also results in the control channel being terminated along
with the associated SIP dialog (issue a BYE request).
o All other error responses received for the SYNC request are
treated as detailed in this specification and also result in the treated as detailed in this specification and also result in the
termination of the control channel and the associated SIP dialog termination of the control channel and the associated SIP dialog
(issue a BYE request). (issue a BYE request).
o The receipt of a 200 response to a SYNCH message implies that the o The receipt of a 200 response to a SYNC message implies that the
SIP dialog and control connection have been successfully SIP dialog and control connection have been successfully
correlated. The control channel can now be used for further correlated. The control channel can now be used for further
interactions. interactions.
It should be noted that SYNCH messages can be sent at any point while SYNC messages can be sent at any point while the Control Channel is
the Control Channel is open from either side, once the initial open from either side, once the initial exchange is complete. If
exchange is complete. It should also be noted that if present, the present, the contents of the "Keep-Alive" and "Dialog-ID" headers
contents of the "Keep-Alive" and "Dialog-ID" headers should not should not change and new values have no relevance as they are both
change and new values have no relevance as they are both negotiated negotiated for the lifetime of the session.
for the lifetime of the session.
Once a successful control channel has been established, as defined in Once a successful control channel has been established, as defined in
Section 4 and Section 5 (and the connection has been correlated, as Section 4.1 and Section 4.2 (and the connection has been correlated,
described in previous paragraph), the two entities are now in a as described in previous paragraphs), the two entities are now in a
position to exchange relevant control framework messages. The position to exchange control framework messages. The following sub-
remainder of this section provides details of the core set of methods sections specify the general behaviour for constructing control
and responses that MUST be supported for the core control framework. framework requests and responses. Section 6.3 specifies the core
Future extensions to this document MAY define new methods and Control Framework methods and their transaction processing.
responses.
6.1. Constructing Requests 6.1. General Behaviour for Constructing Requests
An entity acting as a Control Client is now able to construct and An entity acting as a Control Client that constructs and sends
send new requests on a control channel and MUST adhere to the syntax requests on a control channel MUST adhere to the syntax defined in
defined in Section 9 (Note: either client can act as a control client Section 9 (Note: either entity can act as a control client depending
depending on individual package requirements). Control Commands MUST on individual package requirements). Control Commands MUST also
also adhere to the syntax defined by the Control Packages negotiated adhere to the syntax defined by the Control Packages negotiated in
in Section 4 and Section 5 of this document. A Control Client MUST Section 4.1 and Section 4.2 of this document. A Control Client MUST
create a unique control message transaction and associated identifier create a unique control message transaction and associated identifier
for insertion in the request. The transaction identifier is then for insertion in the request. The transaction identifier is then
included in the first line of a control framework message along with included in the first line of a control framework message along with
the method type (as defined in the ABNF in Section 9). The first the method type (as defined in the ABNF in Section 9). The first
line starts with the "SCFW" token for the purpose of easily line starts with the "CFW" token for the purpose of easily extracting
extracting the transaction identifier. The transaction identifier the transaction identifier. The transaction identifier MUST be
MUST be globally unique over space and time. All required mandatory globally unique over space and time. All required mandatory and
and optional control framework headers are then inserted into the optional control framework headers are then inserted into the control
control message with appropriate values (see relevant individual message with appropriate values (see relevant individual header
header information for explicit detail). A "Control-Package" header information for explicit detail). A "Control-Package" header MUST
MUST also be inserted with the value indicating the Control Package also be inserted with the value indicating the Control Package to
to which this specific request applies (Multiple packages can be which this specific request applies (Multiple packages can be
negotiated per control channel using the SYNCH control message that negotiated per control channel using the SYNC control message
is discussed in this section along with the mechanism from discussed in Section 6.3.4.2).
Section 6.1.4).
Any framework message that contains an associated payload MUST also Any framework message that contains an associated payload MUST also
include a 'Content-Length' and 'Content-Type' message header which include a 'Content-Length' and 'Content-Type' message header which
represents the size of the message body in decimal number of octets. represents the size of the message body in decimal number of octets.
If no associated payload is to be added to the message, a 'Content- If no associated payload is to be added to the message, a 'Content-
Length' header with a value of '0' is considered the same as one not Length' header with a value of '0' is considered the same as one not
being present. being present.
When all of the headers have been included in the framework message, When all of the headers have been included in the framework message,
it is sent down the control channel established in Section 4. it is sent down the control channel.
It is a requirement that a Server receiving such a request respond A Server receiving such a request needs to respond quickly with an
quickly with an appropriate response (as defined in Section 6.2). A appropriate response (as defined in Section 6.2). Control Clients
Control Client entity needs to wait for "Transaction-Time" time for a MUST wait for a minimum of 'Transaction-Timeout' for a response
response before considering the transaction a failure. before considering the transaction a failure.
[Editors Note:DP1 - Need to pick a time for "Transaction-Time" - Work 6.2. General Behaviour for Constructing Responses
Group input requested.]
6.1.1. Sending CONTROL An entity acting as a Control Server, on receiving a request, MUST
generate a response within the 'Transaction-Time'. The response MUST
conform to the ABNF defined in Section 9. The first line of the
response MUST contain the transaction identifier used in first line
of the request, as defined in Section 6.1. Responses MUST NOT
include the 'Status' or 'Timeout' message headers, and these MUST be
ignored if received by a Client in a response.
A 'CONTROL' message is used by Control Client to invoke control A Control Server MUST then include a status code in the first line of
commands on a Control Server. The message is constructed in the same the constructed response. A Control Framework request (like CONTROL)
way as any standard Control Framework message, as discussed that has been understood, and either the actions for the control
previously in Section 6.1 and defined in Section 9. A CONTROL command have completed or a control command error is detected, uses
message MAY contain a message body. The explicit control command(s) the 200 Control Framework status code as defined in Section 7.1. A
of the message payload contained in a CONTROL message are specified 200 response MAY include message bodies. If a 200 response does
in separate Control Package specifications. These specifications contain a payload it MUST include Content-Length and Content-Type
MUST conform to the format defined in Section 8.4. A CONTROL message headers. A 200 is the only response defined in this specification
containing a payload MUST include a 'Content-Type' header indicating that allows a message body to be included. A client receiving a 200
the payload type defined by the control package. class response then considers the control command transaction
completed. A Control Framework request (like CONTROL) that is
received and understood but requires processing that extends beyond
'Transaction-Timeout' will return a 202 status code in the response.
This will be followed by one or more REPORT messages as defined in
Section 6.3.2. A Control Package SHOULD explicitly define the
circumstances under which either 200 or 202 with subsequent
processing takes place.
6.1.2. Sending REPORT If a Control Server encounters problems with a Control Framework
request (like REPORT or CONTROL), an appropriate error code should be
used in the response, as listed in Section 7. The generation of a
non 2xx class response code to a Control Framework request (like
CONTROL or REPORT) will indicate failure of the transaction, and all
associated state and resources should be terminated. The response
code may provide an explicit indication of why the transaction
failed, which might result in a re-submission of the request.
6.3. Transaction Processing
The Control Framework defines four types of messages (methods):
CONTROL, REPORT, K-ALIVE, and SYNC. Implementations MUST support
sending and receiving all four methods. Future extensions to this
document MAY define new methods and responses.
The following sub-sections specify each Control Framework method and
its associated transaction processing.
6.3.1. CONTROL Transactions
A 'CONTROL' message is used by Control Client pass control related
information, such as invoking commands or notifying events, to a
Control Server. The message is constructed in the same way as any
standard Control Framework message, as discussed previously in
Section 6.1 and defined in Section 9. A CONTROL message MAY contain
a message body. The explicit control command(s) of the message
payload contained in a CONTROL message are specified in separate
Control Package specifications. These specifications MUST conform to
the format defined in Section 8.4. A CONTROL message containing a
payload MUST include a 'Content-Type' header indicating the payload
type defined by the control package.
6.3.2. REPORT Transactions
A 'REPORT' message is used by a Control Server when processing of a A 'REPORT' message is used by a Control Server when processing of a
CONTROL Command extends beyond a 'Transaction-Timeout'. In this case CONTROL Command extends beyond a 'Transaction-Timeout'. In this case
a 202 response is returned. Status updates and the final results of a 202 response is returned. Status updates and the final results of
the command are then returned in subsequent REPORT messages. The the command are then returned in subsequent REPORT messages.
extended reporting mechanism defined in Section 6.1.2.1 can be used
for a wide variety of functions including long lived event reporting
associated with a transaction.
[Editors Note:DP2 - Need to pick a time for "Transaction-Time" - Work
Group input requested.]
All REPORT messages MUST contain the same transaction ID in the All REPORT messages MUST contain the same transaction ID in the
request start line that was present in the original CONTROL request start line that was present in the original CONTROL
transaction. This allows both extended transactions and event transaction. This allows both extended transactions and event
notifications to be correlated with the original CONTROL transaction. notifications to be correlated with the original CONTROL transaction.
A REPORT message containing a payload MUST include a 'Content-Length A REPORT message containing a payload MUST include a 'Content-Length
and 'Content-Type' header indicating the payload type defined by the and 'Content-Type' header indicating the payload type defined by the
control package and its length. control package and its length.
6.1.2.1. Reporting the Status of Extended Transactions 6.3.2.1. Reporting the Status of Extended Transactions
On receiving a CONTROL message, a Control Server MUST respond within On receiving a CONTROL message, a Control Server MUST respond within
'Transaction-Timeout' with a status code for the request, as 'Transaction-Timeout' with a status code for the request, as
specified in Section 6.2. If the command completed within that time, specified in Section 6.2. If the command completed within that time,
a 200 response code would have been sent. If the command did not a 200 response code would have been sent. If the command did not
complete within that time, the response code 202 would have been sent complete within that time, the response code 202 would have been sent
indicating that the requested command is still being processed and indicating that the requested command is still being processed and
the CONTROL transaction is being extended. The REPORT method is then the CONTROL transaction is being extended. The REPORT method is then
used to update and terminate the status of the extended transaction. used to update and terminate the status of the extended transaction.
[Editors Note:DP3 - Need to pick a time for "Transaction-Time" - Work
Group input requested.]
A Control Server issuing a 202 response MUST contain a 'Timeout' A Control Server issuing a 202 response MUST contain a 'Timeout'
message header. This header will contain a value in delta seconds message header. This header will contain a value in seconds that
that represents the amount of time the recipient of the 202 message represents the amount of time the recipient of the 202 message must
must wait before assuming that there has been a problem and wait before assuming that there has been a problem and terminating
terminating the extended transaction and associated state (no the extended transaction and associated state (no corresponding
corresponding REPORT message arrived). REPORT message arrived).
The initial REPORT message MUST contain a 'Seq' (Sequence) message The initial REPORT message MUST contain a 'Seq' (Sequence) message
header with a value equal to '1' (It should be noted that the 'Seq' header with a value equal to '1' (It should be noted that the 'Seq'
numbers at both Control Client and Control Server for framework numbers at both Control Client and Control Server for framework
messages are independent). messages are independent).
All REPORT messages for an extended CONTROL transaction MUST contain All REPORT messages for an extended CONTROL transaction MUST contain
a 'Timeout' message header. This header will contain a value in a 'Timeout' message header. This header will contain a value in
delta seconds that represents the amount of time the recipient of the seconds that represents the amount of time the recipient of the
REPORT message must wait before assuming that there has been a REPORT message must wait before assuming that there has been a
problem and terminating the extended transaction and associated problem and terminating the extended transaction and associated
state. On receiving a REPORT message with a 'Status' header of state. On receiving a REPORT message with a 'Status' header of
'pending' or 'update', the Control Client MUST reset the timer for 'update', the Control Client MUST reset the timer for the associated
the associated extended CONTROL transaction to the indicated timeout extended CONTROL transaction to the indicated timeout period. If the
period. If the timeout period approaches with no intended REPORT timeout period approaches with no intended REPORT messages being
messages being generated, the entity acting as a Control Framework generated, the entity acting as a Control Framework UAS for the
UAS for the interaction MUST generate a REPORT message containing, as interaction MUST generate a REPORT message containing, as defined in
defined in this paragraph, a 'Status' header of 'pending'. Such a this paragraph, a 'Status' header of 'update' with no associated
message acts as a timeout refresh and in no way impacts the extended payload. Such a message acts as a timeout refresh and in no way
transaction, because no message body or semantics are permitted. It impacts the extended transaction, because no message body or
is RECOMMENDED that a minimum value of 10 and a maximum of "Upper- semantics are permitted. It is RECOMMENDED that a minimum value of
limit" is used for the value of the 'Timeout' message header. It is 10 and a maximum value of 15 seconds be used for the value of the
also RECOMMENDED that a Control Server refresh the timeout period of 'Timeout' message header. It is also RECOMMENDED that a Control
the CONTROL transaction at an interval that is not too close to the Server refresh the timeout period of the CONTROL transaction at an
expiry time. A value of 80% of the timeout period could be used, for interval that is not too close to the expiry time. A value of 80% of
example a timeout period of 10 seconds would be refreshed after 8 the timeout period could be used, for example a timeout period of 10
seconds. seconds would be refreshed after 8 seconds.
[Editors Note:DP4 - Need to pick a time for "Upper-Limit" - Work
Group input requested.]
Subsequent REPORT messages that provide additional information Subsequent REPORT messages that provide additional information
relating to the extended CONTROL transaction MUST also include and relating to the extended CONTROL transaction MUST also include and
increment by 1 the 'Seq' header value. They MUST also include a increment by 1 the 'Seq' header value. They MUST also include a
'Status' header with a value of 'update'. These REPORT messages sent 'Status' header with a value of 'update'. These REPORT messages sent
to update the extended CONTROL transaction status MAY contain a to update the extended CONTROL transaction status MAY contain a
message body, as defined by individual Control Packages and specified message body, as defined by individual Control Packages and specified
in Section 9.5. A REPORT message sent updating the extended in Section 9.5. A REPORT message sent updating the extended
transaction also acts as a timeout refresh, as described earlier in transaction also acts as a timeout refresh, as described earlier in
this section. This will result in a transaction timeout period at this section. This will result in a transaction timeout period at
skipping to change at page 18, line 41 skipping to change at page 19, line 37
When all processing for an extended CONTROL transaction has taken When all processing for an extended CONTROL transaction has taken
place, the entity acting as a Control Server MUST send a terminating place, the entity acting as a Control Server MUST send a terminating
REPORT message. The terminating REPORT message MUST increment the REPORT message. The terminating REPORT message MUST increment the
value in the 'Seq' message header by the value of '1' from the value in the 'Seq' message header by the value of '1' from the
previous REPORT message. It MUST also include a 'Status' header with previous REPORT message. It MUST also include a 'Status' header with
a value of 'terminate' and MAY contain a message body. A Control a value of 'terminate' and MAY contain a message body. A Control
Framework UAC can then clean up any pending state associated with the Framework UAC can then clean up any pending state associated with the
original control transaction. original control transaction.
6.1.3. Control Channel Keep-Alive 6.3.3. K-ALIVE Transactions
It is reasonable to expect this document to be used in various The protocol defined in this document may be used in various network
network architectures. This will include a wide range of deployments architectures. This will include a wide range of deployments where
where the clients could be co-located in a secured, private domain or the clients could be co-located in a secured, private domain, or
spread across disparate domains that require traversal of devices spread across disparate domains that require traversal of devices
such as Network Address Translators (NAT) and Firewalls. It is such as Network Address Translators (NAT) and Firewalls. A 'keep-
important, therefore, that this document provides a 'keep-alive' alive' mechanism enables the control channel to be kept active during
mechanism that enables the control channel being created to firstly times of inactivity (for example, most Firewalls have a timeout
be kept active during times of inactivity (most Firewalls have a period after which connections are closed). This mechanism also
timeout period after which connections are closed) and also provide provides the ability for application level failure detection. It
the ability for application level failure detection. It should be should be noted that the following procedures apply explicitly to the
noted at this point that the following procedures apply explicitly to control channel being created. For details relating to a SIP keep-
the control channel being created and for details relating to a SIP alive mechanism, implementers should seek guidance from SIP Outbound
keep-alive mechanism implementers should seek guidance from SIP [I-D.ietf-sip-outbound].
Outbound [11]. The following 'keep-alive' procedures SHOULD be
implemented by all entities unless it can be guaranteed that
deployments will only occur with entities in a co-located domain. It
should be noted that choosing to not implement the 'keep-alive'
mechanism in this section, even when in a co-located architecture,
will reduce the ability to detect application level errors -
especially during long periods of in-activity.
6.1.3.1. Timeout Negotiation The following 'keep-alive' procedures MUST be implemented. Specific
deployments MAY choose not to use the keep-alive mechanism if both
entities are in a co-located domain. Note that choosing not to use
the 'keep-alive' mechanism defined in this section, even when in a
co-located architecture, will reduce the ability to detect
application level errors - especially during long periods of in-
activity. Extensions to this specification MAY specify alternate
Control Channel keep-alive mechanisms.
During the creation of the initial SYNCH primitive, the clients will Once the SIP dialog has been established and the underlying control
also negotiate a timeout period for the control channel 'keep-alive' channel has been set-up (including the initial correlation handshake
mechanism. The following rules SHOULD be obeyed: using SYNC as discussed in Section 6), both entities acting in the
'active' and 'passive' roles (as defined in COMEDIA [RFC4145]) MUST
start a keep-alive timer equal to the value negotiated during the
control channel SYNC request/response exchange (the value from the
'k-alive' header in seconds).
6.3.3.1. Behaviour for an Entity in an Active Role
When acting in an 'active' role, a 'K-ALIVE' Control Framework
message MUST be generated before the local 'keep-alive' timer fires.
An active entity is free to send the K-ALIVE Control Framework
message whenever it chooses. A guideline of 80% of the local 'keep-
alive' timer is suggested. On receiving a 200 OK Control Framework
message for the K-ALIVE request, the 'active' entity MUST reset the
local 'keep-alive' timer. If no 200 OK response is received to the
K-ALIVE Control Framework message, before the local 'keep-alive'
timer fires, the 'active' entity SHOULD tear down the SIP dialog and
recover the associated control channel resources. The 'active'
entity MAY choose to try and recover the connection by renegotiation
using COMEDIA.
6.3.3.2. Behaviour for an Entity in an Passive Role
When acting as a 'passive' entity, a 'K-ALIVE' Control Framework
message must be received before the local 'keep-alive' timer fires.
When a K-ALIVE request is received, the 'passive' entity MUST
generate a 200 OK control framework response and reset the local
'keep-alive' timer. No other Control Framework response is valid.
If no K-ALIVE message is received before the local 'keep-alive' timer
fires, the 'passive' entity SHOULD tear down the SIP dialog and
recover the associated control channel resources. The 'active'
entity MAY try to and recover the connection by renegotiating using
COMEDIA.
6.3.4. SYNC Transactions
The initial SYNC request on a control channel is used to negotiate
the timeout period for the control-channel 'keep-alive' mechansim and
to allow clients and servers to learn the Control Packages that each
supports. Subsequent SYNC requests may be used to change the set of
Control Packages that can be used on the vontrol-channel.
6.3.4.1. Timeout Negotiation for the Initial SYNC Transaction
The initial SYNC request allows the timeout period for the control-
channel 'keep-alive' mechanism to be negotiated. The following rules
SHOULD be followed for the initial SYNC request:
o If the Client initiating the SDP "Offer" has a COMEDIA 'setup' o If the Client initiating the SDP "Offer" has a COMEDIA 'setup'
attribute equal to 'active', the 'k-alive' header MUST be included attribute equal to 'active', the 'k-alive' header MUST be included
in the SYNCH message generated by the offerer. The value of the in the SYNC message generated by the offerer. The value of the
'K-Alive' header SHOULD be in the range of 95 and 120 seconds 'K-Alive' header SHOULD be in the range of 95 and 120 seconds
(this is consistent with SIP Outbound[11]). The client that (this is consistent with SIP Outbound[I-D.ietf-sip-outbound]).
generated the SDP "Answer" ('passive' client) MUST copy the The client that generated the SDP "Answer" ('passive' client) MUST
'K-alive' header into the 200 response to the SYNCH message with copy the 'K-alive' header into the 200 response to the SYNC
the same value. message with the same value.
o If the Client initiating the SDP "Offer" has a COMEDIA 'setup' o If the Client initiating the SDP "Offer" has a COMEDIA 'setup'
attribute equal to 'passive', the 'K-alive' header parameter MUST attribute equal to 'passive', the 'K-alive' header parameter MUST
be included in the SYNCH message generated by the answerer. The be included in the SYNC message generated by the answerer. The
value of the 'K-alive' header SHOULD be in the range of 95 and 120 value of the 'K-alive' header SHOULD be in the range of 95 and 120
seconds. The client that generated the SDP "Offer" ('passive' seconds. The client that generated the SDP "Offer" ('passive'
client) MUST copy the 'K-alive' header into the 200 response to client) MUST copy the 'K-alive' header into the 200 response to
the SYNCH message with the same value. the SYNC message with the same value.
o If the Client initiating the SDP "Offer" has a COMEDIA 'setup' o If the Client initiating the SDP "Offer" has a COMEDIA 'setup'
attribute equal to 'actpass', the 'K-Alive' header parameter MUST attribute equal to 'actpass', the 'K-Alive' header parameter MUST
be included in the SYNCH message of the entity who is the 'Active' be included in the SYNC message of the entity who is the 'Active'
participant in the SDP session. If the client generating the participant in the SDP session. If the client generating the
subsequent SDP 'Answer' places a value of 'active' in the COMEDIA subsequent SDP 'Answer' places a value of 'active' in the COMEDIA
SDP 'setup' attribute, it will generate the SYNCH request and SDP 'setup' attribute, it will generate the SYNC request and
include the 'Keep-Alive' header. The value SHOULD be in the range include the 'Keep-Alive' header. The value SHOULD be in the range
95 to 120 seconds. If the client generating the subsequent SDP 95 to 120 seconds. If the client generating the subsequent SDP
'Answer' places a value of 'passive' in the COMDEDIA 'setup' 'Answer' places a value of 'passive' in the COMDEDIA 'setup'
attribute, the original 'Offerer' will generate the SYNCH request attribute, the original 'Offerer' will generate the SYNC request
and include the 'Keep-Alive' header. The value SHOULD be in the and include the 'Keep-Alive' header. The value SHOULD be in the
range 95 to 120 seconds. range 95 to 120 seconds.
o Once negotiated, the keep-alive applies for the remainder of the o If the initial negotiated offer/answer results in a COMEDIA
Control Framework session. Any subsequent SYNCH messages 'setup' attribute equal to 'holdconn', the initial SYNC mechanism
generated in the control channel do not impact the negotiated will occur when the offer/answer exchange is updated and active/
keep-alive property of the session. The "Keep-Alive" header MUST passive roles are delegated using COMEDIA.
NOT be included in subsequent SYNCH messages as it has no meaning.
If it is present it MUST be ignored.
o The 'K-alive' header MUST NOT be included when the COMEDIA 'setup'
attribute is equal to 'holdconn'.
o [Editors Note:DP5 - holdconn needs more thought.]
o Following the previous steps ensures that the entity initiating
the control channel connection is always the one specifying the
keep-alive timeout period. It will always be the initiator of the
connection who generates the 'K-ALIVE' Control Framework level
messages. The following section describes in more detail how to
generate the Control Framework 'K-ALIVE' message.
6.1.3.2. Generating Keep-Alive Messages
Once the SIP dialog has been established using the SDP 'Offer/Answer'
mechanism and the underlying control channel has been established
(including the initial identity handshake using SYNCH as discussed in
Section 6), both the 'active' and 'passive' (as defined in
COMEDIA[6]) clients MUST start a keep-alive timer equal to the value
negotiated during the control channel SYNCH request/response exchange
(the value from the 'k-alive' header in delta seconds).
When acting as an 'active' entity, a 'K-ALIVE' Control Framework The previous steps ensures that the entity initiating the control
message MUST be generated before the local 'keep-alive' timer fires. channel connection is always the one specifying the keep-alive
An active entity is free to send the K-ALIVE Control Framework timeout period. It will always be the initiator of the connection
message when ever it chooses. A guideline of 80% of the local 'keep- who generates the 'K-ALIVE' Control Framework level messages.
alive' timer is suggested. The 'passive' entity MUST generate a 200
OK Control Framework response to the K-ALIVE message and reset the
local 'keep-alive' timer. No other Control Framework response is
valid. On receiving the 200 OK Control Framework message, the
'active' entity MUST reset the local 'keep-alive' timer. If no 200
OK response is received to the K-ALIVE Control Framework message,
before the local 'keep-alive' timer fires, the 'active' entity SHOULD
tear down the SIP dialog and recover the associated control channel
resources. The 'active' entity MAY choose to try and recover the
connection by renegotiation using COMEDIA. It should be noted that
the local 'active' keep-alive timer MUST be reset on receipt of any
Control Framework message (request or response) from the passive
entity.
When acting as a 'passive' entity, a 'K-ALIVE' Control Framework Once negotiated, the keep-alive timeout applies for the remainder of
message MUST be received before the local 'keep-alive' timer fires. the Control Framework session. Any subsequent SYNC messages
The 'passive' entity MUST generate a 200 OK control framework generated in the control channel do not impact the negotiated keep-
response to the K-ALIVE Control Framework message. On sending the alive property of the session. The "Keep-Alive" header MUST NOT be
200 OK response, the 'passive' entity MUST reset the local 'keep- included in subsequent SYNC messages and if it is received it MUST be
alive' timer. If no K-ALIVE message is received before the local ignored.
'keep-alive' timer fires, the 'passive' entity SHOULD tear down the
SIP dialog and recover the associated control channel resources. The
'active' entity MAY try to and recover the connection by
renegotiating using COMEDIA. It should be noted that the local
'passive' keep-alive timer MUST be reset on receipt of any Control
Framework message (request or response) from the active entity.
6.1.4. Package Negotiation 6.3.4.2. Package Negotiation
As part of the SYNCH message exchange a client generating the request As part of the SYNC message exchange a client generating the request
MUST include a "Packages" header, as defined in Section 9. The MUST include a "Packages" header, as defined in Section 9. The
"Packages " header will contain a list of all Control Framework "Packages " header will contain a list of all Control Framework
packages that can be supported within this control session (from the packages that can be supported within this control session (from the
perspective of the entity creating the SYNCH message). All tokens perspective of the client creating the SYNC message). All tokens
MUST be SIP Control Framework packages that adhere to the rules set MUST be Channel Framework packages that adhere to the rules set out
out in Section 8. The initial SYNCH message MUST at least contain a in Section 8. The "Packages" header of the initial SYNC message MUST
single value. contain at least one value.
An entity receiving the initial SYNCH request should carefully An server receiving the initial SYNC request should examine the
examine the contents of the "Packages" header. The entity responding contents of the "Packages" header. If the server supports at least
with a 200 response to the SYNCH header will also populate the one of the packages listed in the request, it MUST respond with a 200
"Packages" header with supported Control Framework packages. This response code. The response MUST contain a "Packages" header that
entry only contain packages that are listed in the received SYNCH lists the supported packages that are in common with those from the
request (either all or a subset). This forms a common set of Control "Packages" header of the request (either all or a subset). This list
Packages that are supported by both parties. Any Control Packages forms a common set of Control Packages that are supported by both
supported by the receiving entity that are not listed in the SYNCH parties. Any Control Packages supported by the server that are not
message MAY be placed in the "Supported" header of the response. listed in the "Packages" header of the SYNC request, MAY be placed in
This is to provide a hint to the client generating the SYNCH message the "Supported" header of the response. This provides a hint to the
that the receiving entity also supports the listed Control Packages. client that generated the SYNC request of the additional packages
supported by the server.
If no packages are supported by the entity receiving the SYNCH If no packages are supported by the server receiving the SYNC
message, it MUST respond with a 422 error response code. The error message, it MUST respond with a 422 error response code. The error
response MUST contain a "Supported" header indicating the packages response MUST contain a "Supported" header indicating the packages
that are supported. The initiating client can then choose to either that are supported. The initiating client can then choose to either
re-submit a new SYNCH message based on the 422 response or consider re-submit a new SYNC message based on the 422 response or consider
the interaction as a failure. This would lead to termination of the the interaction as a failure. This would lead to termination of the
associated SIP dialog by sending a SIP BYE request, as per RFC 3261 associated SIP dialog by sending a SIP BYE request, as per [RFC3261].
[2].
Once the initial SYNCH transaction is completed, either client MAY Once the initial SYNC transaction is completed, either client MAY
choose to send a subsequent new SYNCH Control Framework message to choose to send a subsequent new SYNC Control Framework message to re-
re-negotiate the packages that are supported with the control negotiate the packages that are supported within the control channel.
channel. A new SYNCH message whose Packages header has different A new SYNC message whose Packages header has different values from
values from the previous SYNCH message can effectively add and delete the previous SYNC message can effectively add and delete the packages
the packages used in the control channel. Subsequent SYNCH message used in the control channel. If a client receiving a subsequent SYNC
message does not wish to change the set of packages, it MUST respond
with a 421 Control Framework response code. Subsequent SYNC messages
MUST NOT change the value of the "Dialog-ID" and "Keep-Alive" Control MUST NOT change the value of the "Dialog-ID" and "Keep-Alive" Control
Framework headers that appeared in the original SYNCH negotiation. Framework headers that appeared in the original SYNC negotiation.
If a client receiving a subsequent SYNCH message does not wish to re-
negotiate it MUST respond with a 421 Control Framework response code.
Any Control Framework commands relating to a Control Package that is Any Control Framework commands relating to a Control Package that is
no longer supported by the session are received after re-negotiation, no longer supported by the session which are received after package
the receiving entity SHOULD respond with a 420 response. An entity re-negotiation SHOULD be responded to with a 420 response. An entity
MAY choose to honor such commands for a limited period of time but MAY choose to honor such commands for a limited period of time but
this is implementation specific. this is implementation specific.
6.2. Constructing Responses
A Control Client or Server, on receiving a request, MUST generate a
response within 'Transaction-Time'. The response MUST conform to the
ABNF defined in Section 9. The first line of the response MUST
contain the transaction identifier used in first line of the request,
as defined in Section 6.1. Responses MUST NOT include the 'Status'
or 'Timeout' message headers - if they are included they have no
meaning or semantics.
[Editors Note:DP6 - Need to pick a time for "Transaction-Time" - Work
Group input requested.]
A Control Client or Server MUST then include a status code in the
first line of the constructed response. A Control Framework request
(like CONTROL) that has been understood, and either the relevant
actions for the control command have completed or a control command
error is detected, uses the 200 Control Framework status code as
defined in Section 7.1. A 200 response MAY include message bodies.
If a 200 response does contain a payload it MUST include Content-
Length and Content-Type headers. A 200 is the only response defined
in this specification that allows a message body to be included. A
client receiving a 200 class response then considers the control
command transaction completed. A Control Framework request (like
CONTROL) that is received and understood but requires processing that
extends beyond 'Transaction-Time' time will return a 202 status code
in the response. This will be followed by an REPORT message(s) as
defined in Section 6.1.2. A Control Package SHOULD explicitly define
the circumstances under which either 200 or 202 with subsequent
processing takes place.
[Editors Note:DP7 - Need to pick a time for "Transaction-Time" - Work
Group input requested.]
If a Control Client or Server encounters problems with either a
Control Framework request (like REPORT or CONTROL), an appropriate
error code should be used in the response, as listed in Section 7.
The generation of a non 2xx class response code to either a Control
Framework request (like CONTROL or REPORT) will indicate failure of
the transaction, and all associated state and resources should be
terminated. The response code may provide an explicit indication of
why the transaction failed, which might result in a re-submission of
the request.
7. Response Code Descriptions 7. Response Code Descriptions
The following response codes are defined for transaction responses to The following response codes are defined for transaction responses to
methods defined in Section 6.1. All response codes in this section methods defined in Section 6.1. All response codes in this section
MUST be supported and can be used in response to both CONTROL and MUST be supported and can be used in response to both CONTROL and
REPORT messages except that a 202 MUST NOT be generated in response REPORT messages except that a 202 MUST NOT be generated in response
to a REPORT message. to a REPORT message.
Note that these response codes apply to framework transactions only. Note that these response codes apply to framework transactions only.
Success or error indications for control commands MUST be treated as Success or error indications for control commands MUST be treated as
skipping to change at page 23, line 27 skipping to change at page 23, line 35
or REPORT message. or REPORT message.
7.1. 200 Response Code 7.1. 200 Response Code
The 200 code indicates the completion of a successful transaction. The 200 code indicates the completion of a successful transaction.
7.2. 202 Response Code 7.2. 202 Response Code
The 202 response code indicates the completion of a successful The 202 response code indicates the completion of a successful
transaction with additional information to be provided at a later transaction with additional information to be provided at a later
time through the REPORT mechanism defined in Section 6.1.2. time through the REPORT mechanism defined in Section 6.3.2.
7.3. 400 Response Code 7.3. 400 Response Code
The 400 response indicates that the request was syntactically The 400 response indicates that the request was syntactically
incorrect. incorrect.
7.4. 403 Response Code 7.4. 403 Response Code
The server understood the request, but is refusing to fulfill it. The server understood the request, but is refusing to fulfill it.
The request SHOULD NOT be repeated. The request SHOULD NOT be repeated.
skipping to change at page 24, line 12 skipping to change at page 24, line 17
Intended target of the request is for a Control Package that is not Intended target of the request is for a Control Package that is not
valid for the current session. valid for the current session.
7.7. 421 Response Code 7.7. 421 Response Code
Recipient does not wish to re-negotiate Control Packages at this Recipient does not wish to re-negotiate Control Packages at this
moment in time. moment in time.
7.8. 422 Response Code 7.8. 422 Response Code
Recipient does not support any Control Packages listed in the SYNCH Recipient does not support any Control Packages listed in the SYNC
message. message.
7.9. 423 Response Code 7.9. 423 Response Code
Recipient already has a transaction with the same transaction ID. Recipient already has a transaction with the same transaction ID.
7.10. 481 Response Code 7.10. 481 Response Code
The 481 response indicates that the transaction of the request does The 481 response indicates that the transaction of the request does
not exist. not exist. In response to a SYNC request, it indicates that the
corresponding SIP dialog does not exist.
7.11. 500 Response Code 7.11. 500 Response Code
The 500 response indicates that the recipient does not understand the The 500 response indicates that the recipient does not understand the
request request
8. Control Packages 8. Control Packages
"Control Packages" are intended to specify behavior that extends the "Control Packages" are intended to specify behavior that extends the
the capability defined in this document. "Control Packages" are not the capability defined in this document. "Control Packages" are not
skipping to change at page 25, line 25 skipping to change at page 25, line 34
control channel. This section of a Control package document should control channel. This section of a Control package document should
explicitly detail the control messages that can be used as well as explicitly detail the control messages that can be used as well as
provide an indication of directionality between entities. This will provide an indication of directionality between entities. This will
include which role type is allowed to initiate a request type. include which role type is allowed to initiate a request type.
8.3. Common XML Support 8.3. Common XML Support
This optional section is only included in a Control Package if the This optional section is only included in a Control Package if the
attributes for media dialog or Conference reference are required. attributes for media dialog or Conference reference are required.
The Control Package will make strong statements (MUST strength) if The Control Package will make strong statements (MUST strength) if
the XML schema defined in Section 16.1 in Appendix A is to be the XML schema defined in Section 17.1 in Appendix A is to be
supported. If only part of the schema is required (for example just supported. If only part of the schema is required (for example just
'connection-id' or just conf-id), the Control Package will make 'connectionid' or just conferenceid), the Control Package will make
equally strong (MUST strength) statements. equally strong (MUST strength) statements.
8.4. CONTROL Message Bodies 8.4. CONTROL Message Bodies
This mandatory section of a Control Package defines the control body This mandatory section of a Control Package defines the control body
that can be contained within a CONTROL command request, as defined in that can be contained within a CONTROL command request, as defined in
Section 6 (or that no control package body is required). This Section 6 (or that no control package body is required). This
section should indicate the location of detailed syntax definitions section should indicate the location of detailed syntax definitions
and semantics for the appropriate body types. and semantics for the appropriate body types.
skipping to change at page 26, line 7 skipping to change at page 26, line 13
should indicate the location of detailed syntax definitions and should indicate the location of detailed syntax definitions and
semantics for the appropriate body types. It should be noted that semantics for the appropriate body types. It should be noted that
the Control Framework specification does allow for payloads to exist the Control Framework specification does allow for payloads to exist
in 200 responses to CONTROL messages (as defined in this document). in 200 responses to CONTROL messages (as defined in this document).
An entity that is prepared to receive a payload type in a REPORT An entity that is prepared to receive a payload type in a REPORT
message MUST also be prepared to receive the same payload in a 200 message MUST also be prepared to receive the same payload in a 200
response to a CONTROL message. response to a CONTROL message.
8.6. Audit 8.6. Audit
[EDITORS NOTE: DP12 - Need to include audit template mechanism.] Auditing of various control package properties is extremely useful.
Control Packages are encouraged to make use of Control Framework
interactions to provide relevant package audit information.
This section should include information including:
o If an auditing capability is available in this package.
o How auditing information is triggered (for example, using Control
framework CONTROL message) and delivered (for example in a Control
Framework 200 response).
o The location of the audit query and response format for the
payload (for example, it could be a separate XML schema OR part of
a larger XML schema).
8.7. Examples 8.7. Examples
It is strongly recommended that Control Packages provide a range of It is strongly recommended that Control Packages provide a range of
message flows that represent common flows using the package and this message flows that represent common flows using the package and this
framework document. framework document.
9. Formal Syntax 9. Formal Syntax
9.1. Control Framework Formal Syntax 9.1. Control Framework Formal Syntax
The Control Framework interactions use the UTF-8 transformation The Control Framework interactions use the UTF-8 transformation
format as defined in RFC3629 [16]. The syntax in this section uses format as defined in [RFC3629]. The syntax in this section uses the
the Augmented Backus-Naur Form (ABNF) as defined in RFC2234 [17]. Augmented Backus-Naur Form (ABNF) as defined in [RFC2234].
control-req-or-resp = control-request / control-response control-req-or-resp = control-request / control-response
control-request = control-req-start *( headers ) CRLF [control-content] control-request = control-req-start *( headers ) CRLF [control-content]
control-response = control-resp-start *( headers ) CRLF [control-content] control-response = control-resp-start *( headers ) CRLF [control-content]
control-req-start = pSCFW SP transact-id SP method CRLF control-req-start = pCFW SP transact-id SP method CRLF
control-resp-start = pSCFW SP transact-id SP status-code [SP comment] CRLF control-resp-start = pCFW SP transact-id SP status-code [SP comment] CRLF
comment = utf8text comment = utf8text
pSCFW = %x53.43.46.57; SCFW in caps pCFW = %x43.46.57; CFW in caps
transact-id = alpha-num-token transact-id = alpha-num-token
method = mCONTROL / mREPORT / mSYNCH / mK-ALIVE / other-method method = mCONTROL / mREPORT / mSYNC / mK-ALIVE / other-method
mCONTROL = %x43.4F.4E.54.52.4F.4C; CONTROL in caps mCONTROL = %x43.4F.4E.54.52.4F.4C; CONTROL in caps
mREPORT = %x52.45.50.4F.52.54; REPORT in caps mREPORT = %x52.45.50.4F.52.54; REPORT in caps
mSYNCH = %x53.59.4E.43.48; SYNCH in caps mSYNC = %x53.59.4E.43; SYNC in caps
mK-ALIVE = %x4B.2D.41.4C.49.56.45;K-ALIVE in caps mK-ALIVE = %x4B.2D.41.4C.49.56.45;K-ALIVE in caps
other-method = 1*UPALPHA other-method = 1*UPALPHA
status-code = 3DIGIT ; any code defined in this and other documents status-code = 3DIGIT ; any code defined in this and other documents
headers = header-name CRLF headers = header-name CRLF
header-name = (Content-Length header-name = (Content-Length
/Content-Type
/Control-Package /Control-Package
/Status /Status
/Seq /Seq
/Timeout /Timeout
/Dialog-id /Dialog-id
/Packages /Packages
/Supported /Supported
/Keep-alive /Keep-alive
/ext-header) CRLF /ext-header) CRLF
Content-Length = "Content-Length:" SP 1*DIGIT Content-Length = "Content-Length:" SP 1*DIGIT
Control-Package = "Control-Package:" SP 1*alpha-num-token Control-Package = "Control-Package:" SP 1*alpha-num-token
Status = "Status:" SP ("pending" / "update" / "terminate" ) Status = "Status:" SP ("update" / "terminate" )
Timeout = "Timeout:" SP 1*DIGIT Timeout = "Timeout:" SP 1*DIGIT
Seq = "Seq:" SP 1*DIGIT Seq = "Seq:" SP 1*DIGIT
Dialog-id = "Dialog-ID:" SP dialog-id-string Dialog-id = "Dialog-ID:" SP dialog-id-string
Packages = "Packages:" SP package-name *(COMMA package-name) Packages = "Packages:" SP package-name *(COMMA package-name)
Supported = "Supported:" SP supported *(COMMA supported) Supported = "Supported:" SP supported *(COMMA supported)
Keep-alive = "Keep-Alive:" SP delta-seconds Keep-alive = "Keep-Alive:" SP kalive-seconds
dialog-id-string = alpha-num-token "~" alpha-num-token ["~" alpha-num-token] dialog-id-string = alpha-num-token "~" alpha-num-token ["~" alpha-num-token]
package-name = alpha-num-token package-name = alpha-num-token
supported = alpha-num-token supported = alpha-num-token
delta-seconds = 1*DIGIT kalive-seconds = 1*DIGIT
alpha-num-token = alphanum 3*31alpha-num-tokent-char alpha-num-token = alphanum 3*31alpha-num-tokent-char
alpha-num-tokent-char = alphanum / "." / "-" / "+" / "%" / "=" alpha-num-tokent-char = alphanum / "." / "-" / "+" / "%" / "="
control-content = Content-Type 2CRLF data CRLF control-content = data CRLF
Content-Type = "Content-Type:" SP media-type Content-Type = "Content-Type:" SP media-type
media-type = type "/" subtype *( ";" gen-param ) media-type = type "/" subtype *( ";" gen-param )
type = token type = token
subtype = token subtype = token
gen-param = pname [ "=" pval ] gen-param = pname [ "=" pval ]
pname = token pname = token
pval = token / quoted-string pval = token / quoted-string
token = 1*(%x21 / %x23-27 / %x2A-2B / %x2D-2E token = 1*(%x21 / %x23-27 / %x2A-2B / %x2D-2E
/ %x30-39 / %x41-5A / %x5E-7E) / %x30-39 / %x41-5A / %x5E-7E)
; token is compared case-insensitive ; token is compared case-insensitive
quoted-string = DQUOTE *(qdtext / qd-esc) DQUOTE quoted-string = DQUOTE *(qdtext / qd-esc) DQUOTE
qdtext = SP / HTAB / %x21 / %x23-5B / %x5D-7E qdtext = SP / HTAB / %x21 / %x23-5B / %x5D-7E
/ UTF8-NONASCII / UTF8-NONASCII
skipping to change at page 29, line 5 skipping to change at page 29, line 10
An empty entry in the "where" column indicates that the header An empty entry in the "where" column indicates that the header
field may be present in all requests and responses. field may be present in all requests and responses.
The remaining columns list the specified methods and the presence of The remaining columns list the specified methods and the presence of
a specific header: a specific header:
m: The header field is mandatory. m: The header field is mandatory.
o: The header field is optional. o: The header field is optional.
-: The header field is not applicable (ignored if present). -: The header field is not applicable (ignored if present).
Header field Where CONTROL REPORT SYNCH K-ALIVE Header field Where CONTROL REPORT SYNC K-ALIVE
___________________________________________________________ ___________________________________________________________
Content-Length o o - - Content-Length o o - -
Control-Package R m - - - Control-Package R m - - -
Seq - m - - Seq - m - -
Status R - m - - Status R - m - -
Timeout R - m - - Timeout R - m - -
Dialog-ID R - - m - Dialog-ID R - - m -
Packages - - m - Packages - - m -
Supported r - - o - Supported r - - o -
Keep-Alive R - - o - Keep-Alive R - - o -
Content-Type o o - -
Figure 10: Table 1 Figure 3: Table 1
9.2. Control Framework Dialog Identifier SDP Attribute
This specification defines a new media-level value attribute:
'cfw-id'. Its formatting in SDP is described by the following
ABNF[RFC5234].
cfw-dialog-id = "a=cfw-id:" 1*(SP cfw-id-name) CRLF
cfw-id-name = token
token = 1*(token-char)
token-char = %x21 / %x23-27 / %x2A-2B / %x2D-2E / %x30-39
/ %x41-5A / %x5E-7E
The token-char and token elements are defined in [RFC4566] but
included here to provide support for the implementer of this SDP
feature.
10. Examples 10. Examples
The following examples provide an abstracted flow of Control Channel The following examples provide an abstracted flow of Control Channel
establishment and Control Framework message exchange. The SIP establishment and Control Framework message exchange. The SIP
signaling is prefixed with the token 'SIP'. All other messages are signaling is prefixed with the token 'SIP'. All other messages are
Control Framework interactions defined in this document. Control Framework interactions defined in this document.
In this example, the Control Client establishes a control channel, In this example, the Control Client establishes a control channel,
SYNCHs with the Control Server, and issues a CONTROL request that SYNCs with the Control Server, and issues a CONTROL request that
can't be completed within "transaction-timeout" seconds, so the can't be completed within the 'Transaction-Timeout' of, so the
Control Server returns a 202 response code to extend the Control Server returns a 202 response code to extend the transaction.
trqansaction. The Control Server then follows with REPORTs until the The Control Server then follows with REPORTs until the requested
requested action has been completed. The SIP dialog is then action has been completed. The SIP dialog is then terminated.
terminated.
[Editors Note:DP8 - Need to pick a time for "Transaction-Time" - Work
Group input requested.]
Control Client Control Server Control Client Control Server
| | | |
| (1) SIP INVITE | | (1) SIP INVITE |
| ----------------------------------------> | | ----------------------------------------> |
| | | |
| (2) SIP 200 | | (2) SIP 200 |
| <--------------------------------------- | | <--------------------------------------- |
| | | |
| (3) SIP ACK | | (3) SIP ACK |
| ----------------------------------------> | | ----------------------------------------> |
| | | |
|==>=======================================>==| |==>=======================================>==|
| Control Channel Established | | Control Channel Established |
|==>=======================================>==| |==>=======================================>==|
| | | |
| (4) SYNCH | | (4) SYNC |
| ----------------------------------------> | | ----------------------------------------> |
| | | |
| (5) 200 | | (5) 200 |
| <--------------------------------------- | | <--------------------------------------- |
| | | |
| (6) CONTROL | | (6) CONTROL |
| ----------------------------------------> | | ----------------------------------------> |
| | | |
| (7) 202 | | (7) 202 |
| <--------------------------------------- | | <--------------------------------------- |
| | | |
| (8) REPORT (pending) | | (8) REPORT (update) |
| <---------------------------------------- | | <---------------------------------------- |
| | | |
| (9) 200 | | (9) 200 |
| ----------------------------------------> | | ----------------------------------------> |
| | | |
| (10) REPORT (update) | | (10) REPORT (update) |
| <---------------------------------------- | | <---------------------------------------- |
| | | |
| (11) 200 | | (11) 200 |
| ----------------------------------------> | | ----------------------------------------> |
skipping to change at page 31, line 18 skipping to change at page 31, line 43
CSeq: 1 INVITE CSeq: 1 INVITE
Call-ID: 893jhoeihjr8392@example.com Call-ID: 893jhoeihjr8392@example.com
Contact: <sip:control-client@pc1.example.com> Contact: <sip:control-client@pc1.example.com>
Content-Type: application/sdp Content-Type: application/sdp
Cotent-Length: [..] Cotent-Length: [..]
v=0 v=0
o=originator 2890844526 2890842808 IN IP4 controller.example,com o=originator 2890844526 2890842808 IN IP4 controller.example,com
s=- s=-
c=IN IP4 control-client.example.com c=IN IP4 control-client.example.com
m=application 7575 TCP/SCFW m=application 7575 TCP/CFW
a=setup:active a=setup:active
a=connection:new a=connection:new
a=cfw-id:fndskuhHKsd783hjdla
2. Control Server->Control Client (SIP): 200 OK 2. Control Server->Control Client (SIP): 200 OK
SIP/2.0 200 OK SIP/2.0 200 OK
To: <sip:control-server@example.com>;tag=023983774 To: <sip:control-server@example.com>;tag=023983774
From: <sip:control-client@example.com>;tag=8937498 From: <sip:control-client@example.com>;tag=8937498
Via: SIP/2.0/UDP control-client.example.com;branch=z9hG412345678 Via: SIP/2.0/UDP control-client.example.com;branch=z9hG412345678
CSeq: 1 INVITE CSeq: 1 INVITE
Call-ID: 893jhoeihjr8392@example.com Call-ID: 893jhoeihjr8392@example.com
Contact: <sip:control-client@pc2.example.com> Contact: <sip:control-client@pc2.example.com>
Content-Type: application/sdp Content-Type: application/sdp
Content-Length: [..] Content-Length: [..]
v=0 v=0
o=originator 2890844526 2890842808 IN IP4 controller.example,com o=originator 2890844526 2890842808 IN IP4 controller.example,com
s=- s=-
c=IN IP4 control-server.example.com c=IN IP4 control-server.example.com
m=application 7575 TCP/SCFW m=application 7575 TCP/CFW
a=setup:passive a=setup:passive
a=connection:new a=connection:new
a=cfw-id:fndskuhHKsd783hjdla
3. Control Client->Control Server (SIP): ACK 3. Control Client->Control Server (SIP): ACK
4. Control Client opens a TCP connection to the Control Server. 4. Control Client opens a TCP connection to the Control Server.
The connection can now be used to exchange control framework The connection can now be used to exchange control framework
messages. Control Client-->Control Server (Control Framework messages. Control Client-->Control Server (Control Framework
Message): SYNCH. Message): SYNC.
SCFW 8djae7khauj SYNCH CFW 8djae7khauj SYNC
Dialog-ID: 8937498~893jhoeihjr8392@example.com~023983774 Dialog-ID: fndskuhHKsd783hjdla
K-alive: 100 K-alive: 100
Packages: msc-ivr-basic/1.0 Packages: msc-ivr-basic/1.0
5. Control Server-->Control Client (Control Framework Message): 5. Control Server-->Control Client (Control Framework Message):
200. 200.
SCFW 8djae7khauj 200 CFW 8djae7khauj 200
Keep-Alive: 100 Keep-Alive: 100
Packages: msc-ivr-basic/1.0 Packages: msc-ivr-basic/1.0
Supported: msc-ivr-vxml/1.0,msc-conf-audio/1.0 Supported: msc-ivr-vxml/1.0,msc-conf-audio/1.0
6. Control Client opens a TCP connection to the Control Server. 6. Control Client opens a TCP connection to the Control Server.
The connection can now be used to exchange control framework The connection can now be used to exchange control framework
messages. Control Client-->Control Server (Control Framework messages. Control Client-->Control Server (Control Framework
Message): CONTROL. Message): CONTROL.
SCFW i387yeiqyiq CONTROL CFW i387yeiqyiq CONTROL
Control-Package: <package-name> Control-Package: <package-name>
Content-Type: example_content/example_content Content-Type: example_content/example_content
Content-Length: 11 Content-Length: 11
<XML BLOB/> <XML BLOB/>
7. Control Server-->Control Client (Control Framework Message): 7. Control Server-->Control Client (Control Framework Message):
202. 202.
SCFW i387yeiqyiq 202 CFW i387yeiqyiq 202
Timeout: 10 Timeout: 10
8. Control Server-->Control Client (Control Framework Message): 8. Control Server-->Control Client (Control Framework Message):
REPORT. REPORT.
SCFW i387yeiqyiq REPORT CFW i387yeiqyiq REPORT
Seq: 1 Seq: 1
Status: pending Status: update
Timeout: 10 Timeout: 10
9. Control Client-->Control Server (Control Framework Message): 9. Control Client-->Control Server (Control Framework Message):
200. 200.
SCFW i387yeiqyiq 200 CFW i387yeiqyiq 200
Seq: 1 Seq: 1
10. Control Server-->Control Client (Control Framework Message): 10. Control Server-->Control Client (Control Framework Message):
REPORT. REPORT.
SCFW i387yeiqyiq REPORT CFW i387yeiqyiq REPORT
Seq: 2 Seq: 2
Status: update Status: update
Timeout: 10 Timeout: 10
Content-Type: example_content/example_content Content-Type: example_content/example_content
Content-Length: 11 Content-Length: 11
<XML BLOB/> <XML BLOB/>
11. Control Client-->Control Server (Control Framework Message): 11. Control Client-->Control Server (Control Framework Message):
200. 200.
SCFW i387yeiqyiq 200 CFW i387yeiqyiq 200
Seq: 2 Seq: 2
12. Control Server-->Control Client (Control Framework Message): 12. Control Server-->Control Client (Control Framework Message):
REPORT. REPORT.
SCFW i387yeiqyiq REPORT CFW i387yeiqyiq REPORT
Seq: 3 Seq: 3
Status: terminate Status: terminate
Timeout: 10 Timeout: 10
Content-Type: example_content/example_content Content-Type: example_content/example_content
Content-Length: 11 Content-Length: 11
<XML BLOB/> <XML BLOB/>
13. Control Client-->Control Server (Control Framework Message): 13. Control Client-->Control Server (Control Framework Message):
200. 200.
SCFW i387yeiqyiq 200 CFW i387yeiqyiq 200
Seq: 3 Seq: 3
14. Control Client->Control Server (SIP): BYE 14. Control Client->Control Server (SIP): BYE
BYE sip:control-client@pc2.example.com SIP/2.0 BYE sip:control-client@pc2.example.com SIP/2.0
To: <sip:control-server@example.com> To: <sip:control-server@example.com>
From: <sip:control-client@example.com>;tag=8937498 From: <sip:control-client@example.com>;tag=8937498
Via: SIP/2.0/UDP control-client.example.com;branch=z9hG423456789 Via: SIP/2.0/UDP control-client.example.com;branch=z9hG423456789
CSeq: 2 BYE CSeq: 2 BYE
Call-ID: 893jhoeihjr8392@example.com Call-ID: 893jhoeihjr8392@example.com
skipping to change at page 34, line 4 skipping to change at page 34, line 32
14. Control Client->Control Server (SIP): BYE 14. Control Client->Control Server (SIP): BYE
BYE sip:control-client@pc2.example.com SIP/2.0 BYE sip:control-client@pc2.example.com SIP/2.0
To: <sip:control-server@example.com> To: <sip:control-server@example.com>
From: <sip:control-client@example.com>;tag=8937498 From: <sip:control-client@example.com>;tag=8937498
Via: SIP/2.0/UDP control-client.example.com;branch=z9hG423456789 Via: SIP/2.0/UDP control-client.example.com;branch=z9hG423456789
CSeq: 2 BYE CSeq: 2 BYE
Call-ID: 893jhoeihjr8392@example.com Call-ID: 893jhoeihjr8392@example.com
15. Control Server->Control Client (SIP): 200 OK 15. Control Server->Control Client (SIP): 200 OK
SIP/2.0 200 OK SIP/2.0 200 OK
To: <sip:control-server@example.com>;tag=023983774 To: <sip:control-server@example.com>;tag=023983774
From: <sip:control-client@example.com>;tag=8937498 From: <sip:control-client@example.com>;tag=8937498
Via: SIP/2.0/UDP control-client.example.com;branch=z9hG423456789 Via: SIP/2.0/UDP control-client.example.com;branch=z9hG423456789
CSeq: 2 BYE CSeq: 2 BYE
Call-ID: 893jhoeihjr8392@example.com Call-ID: 893jhoeihjr8392@example.com
11. Security Considerations 11. Security Considerations
SIP Control Framework needs to provide confidentiality and integrity Channel Framework needs to provide confidentiality and integrity for
for the messages it transfers. It also needs to provide assurances the messages it transfers. It also needs to provide assurances that
that the connected host is the host that it meant to connect to and the connected host is the host that it meant to connect to and that
that the connection has not been hijacked. the connection has not been hijacked.
SIP Control Framework is designed to comply with the security-related Channel Framework is designed to comply with the security-related
requirements documented in the control prtoocol requirements requirements documented in the control protocol requirements
document[8]. Specific security measures employed by the SIP Control document[RFC5167]. Specific security measures employed by the
Framework are summarized in the following subsections. Channel Framework are summarized in the following subsections.
11.1. Session Establishment 11.1. Session Establishment
SIP Control Framework sessions are established as media sessions ChannelFramework sessions are established as media sessions described
described by SDP within the context of a SIP dialog. In order to by SDP within the context of a SIP dialog. In order to ensure secure
ensure secure rendezvous between Control Framework clients and rendezvous between Control Framework clients and servers, the Media
servers, the following are required: Channel Control Framework should make full use of mechanism provided
by the SIP protocol.
o The SIP implementation in Control Framework clients and servers
MUST support digest authentication as specified in RFC3261 [2] and
'Enhancements for Authenticated Identity Management in the Session
Initiation Protocol (SIP)[18].
o The SIP implementation in Control Framework clients and servers
SHOULD employ SIPS: URIs as specified in RFC3261 [2].
[EDITORS NOTE:DP9 - Sip identity - is this too strong?]
[EDITORS NOTE:DP10 - WHAT DO WE SAY ABOUT S/MIME????]
11.2. Transport Level Protection 11.2. Transport Level Protection
When using only TCP connections, the SIP Control Framework security When using only TCP connections, the Channel Framework security is
is weak. Although the SIP Control Framework requires the ability to weak. Although the Channel Framework requires the ability to protect
protect this exchange, there is no guarantee that the protection will this exchange, there is no guarantee that the protection will be used
be used all the time. If such protection is not used, anyone can see all the time. If such protection is not used, anyone can see data
data exchanges. exchanges.
Sensitive data is carried over the Control Framework channel. Sensitive data is carried over the Control Framework channel.
Clients and servers must be properly authenticated and the control Clients and servers must be properly authenticated and the control
channel must permit the use of both confidentiality and integrity for channel must permit the use of both confidentiality and integrity for
the data. To ensure control channel protection, Control Framework the data. To ensure control channel protection, Control Framework
clients and servers MUST support TLS and SHOULD utilize it by default clients and servers MUST support TLS and SHOULD utilize it by default
unless alternative control channel protection is used or a protected unless alternative control channel protection is used or a protected
environment is guaranteed. Alternative control channel protection environment is guaranteed. Alternative control channel protection
MAY be used if desired (e.g.IPSEC). MAY be used if desired (e.g.IPSEC).
TLS is used to authenticate devices and to provide integrity and TLS is used to authenticate devices and to provide integrity and
confidentiality for the header fields being transported on the confidentiality for the header fields being transported on the
control chanel. SIP Control Framowork elements MUST implement TLS control channel. Channel Framework elements MUST implement TLS and
and MUST also implement the TLS ClientExtendedHello extended hello MUST also implement the TLS ClientExtendedHello extended hello
information for server name indication as described in [19]. A TLS information for server name indication as described in [RFC4366]. A
cipher-suite of TLS_RSA_WITH_AES_128_CBC_SHA[2] MUST be supported TLS cipher-suite of TLS_RSA_WITH_AES_128_CBC_SHA[RFC3261] MUST be
(other cipher-suites MAY also be supported). supported (other cipher-suites MAY also be supported).
11.3. Control Channel Policy Management 11.3. Control Channel Policy Management
This specification permits the establishment of a dedicated control This specification permits the establishment of a dedicated control
channel using SIP. It is also permitted for entities to create channel using SIP. It is also permitted for entities to create
multiple channels for the purpose of failover and redundancy. As a multiple channels for the purpose of failover and redundancy. As a
general solution, the ability for multiple entities to create general solution, the ability for multiple entities to create
connections and have access to resources could be the cause of connections and have access to resources could be the cause of
potential conflict in shared environments. It should be noted that potential conflict in shared environments. It should be noted that
this document does not specifically carry any specific mechanism to this document does not specifically carry any specific mechanism to
skipping to change at page 36, line 8 skipping to change at page 36, line 26
mechanism such as mutual TLS authentication on the control channel. mechanism such as mutual TLS authentication on the control channel.
This specification provide a control channel response code(403) to This specification provide a control channel response code(403) to
indicate to the issuer of a command that it is not permitted. It indicate to the issuer of a command that it is not permitted. It
should be noted that additional policy requirements might be defined should be noted that additional policy requirements might be defined
and applied in individual packages that specify a finer granularity and applied in individual packages that specify a finer granularity
for access to resources etc. for access to resources etc.
12. IANA Considerations 12. IANA Considerations
This specification instructs IANA to create a new registry for SIP This specification instructs IANA to create a new registry for SIP
Control Framework parameters. The SIP Control Framework Parameter Control Framework parameters. The Channel Framework Parameter
registry is a container for sub-registries. This section further registry is a container for sub-registries. This section further
introduces sub-registries for SIP Control Framework packages, method introduces sub-registries for Channel Framework packages, method
names, status codes, header field names, port and transport protocol. names, status codes, header field names, port and transport protocol.
Additionally, Section 12.6 registers new parameters in existing IANA Additionally, Section 12.6 registers new parameters in existing IANA
registries. registries.
12.1. Control Packages Registration Information 12.1. Control Packages Registration Information
This specification establishes the Control Packages sub-registry This specification establishes the Control Packages sub-registry
under Control Framework Packages. New parameters in this sub- under Control Framework Packages. New parameters in this sub-
registry must be published in an RFC (either as an IETF submission or registry must be published in an RFC (either as an IETF submission or
skipping to change at page 37, line 8 skipping to change at page 37, line 14
Package Name Contact Reference Package Name Contact Reference
------------ ------- --------- ------------ ------- ---------
example1 [Boulton] example1 [Boulton]
example2 [Boulton] [RFCXXX] example2 [Boulton] [RFCXXX]
example3 [RFCXXX] example3 [RFCXXX]
12.1.1. Control Package Registration Template 12.1.1. Control Package Registration Template
To: ietf-sip-control@iana.org To: ietf-sip-control@iana.org
Subject: Registration of new SIP Control Framework package Subject: Registration of new Channel Framework package
Package Name: Package Name:
(Package names must conform to the syntax described in (Package names must conform to the syntax described in
section 8.1.) section 8.1.)
Published Specification(s): Published Specification(s):
(Control packages require a published RFC.). (Control packages require a published RFC.).
skipping to change at page 37, line 30 skipping to change at page 37, line 36
12.2. Control Framework Method Names 12.2. Control Framework Method Names
This specification establishes the Methods sub-registry under Control This specification establishes the Methods sub-registry under Control
Framework Parameters and initiates its population as follows. New Framework Parameters and initiates its population as follows. New
parameters in this sub-registry must be published in an RFC (either parameters in this sub-registry must be published in an RFC (either
as an IETF submission or RFC Editor submission). as an IETF submission or RFC Editor submission).
CONTROL - [RFCXXX] CONTROL - [RFCXXX]
REPORT - [RFCXXX] REPORT - [RFCXXX]
SYNCH - [RFCXXX] SYNC - [RFCXXX]
The following information MUST be provided in an RFC publication in The following information MUST be provided in an RFC publication in
o The method name. o The method name.
o The RFC number in which the method is registered. o The RFC number in which the method is registered.
12.3. Control Framework Status Codes 12.3. Control Framework Status Codes
This specification establishes the Status-Code sub-registry under SIP This specification establishes the Status-Code sub-registry under
Control Framework Parameters. New parameters in this sub-registry Channel Framework Parameters. New parameters in this sub-registry
must be published in an RFC (either as an IETF submission or RFC must be published in an RFC (either as an IETF submission or RFC
Editor submission). Its initial population is defined in Section 9. Editor submission). Its initial population is defined in Section 9.
It takes the following format: It takes the following format:
Code [RFC Number] Code [RFC Number]
The following information MUST be provided in an RFC publication in The following information MUST be provided in an RFC publication in
order to register a new Control Framework status code: order to register a new Control Framework status code:
o The status code number. o The status code number.
o The RFC number in which the method is registered. o The RFC number in which the method is registered.
12.4. Control Framework Header Fields 12.4. Control Framework Header Fields
This specification establishes the header field-Field sub-registry This specification establishes the header field-Field sub-registry
under SIP Control Framework Parameters. New parameters in this sub- under Channel Framework Parameters. New parameters in this sub-
registry must be published in an RFC (either as an IETF submission or registry must be published in an RFC (either as an IETF submission or
RFC Editor submission). Its initial population is defined as RFC Editor submission). Its initial population is defined as
follows: follows:
Control-Package - [RFCXXXX] Control-Package - [RFCXXXX]
Status - [RFCXXXX] Status - [RFCXXXX]
Seq - [RFCXXXX] Seq - [RFCXXXX]
Timeout - [RFCXXXX] Timeout - [RFCXXXX]
Dialog-id - [RFCXXXX] Dialog-id - [RFCXXXX]
Packages - [RFCXXXX] Packages - [RFCXXXX]
Supported - [RFCXXXX] Supported - [RFCXXXX]
Keep-alive - [RFCXXXX] Keep-alive - [RFCXXXX]
Content-Type - [RFCXXXX]
The following information MUST be provided in an RFC publication in The following information MUST be provided in an RFC publication in
order to register a new SIP Control Framework header field: order to register a new Channel Framework header field:
o The header field name. o The header field name.
o The RFC number in which the method is registered. o The RFC number in which the method is registered.
12.5. Control Framework Port 12.5. Control Framework Port
[Editors Note:DP11 - To be discussed]. The Control Framework uses TCP port XXXX, from the "registered" port
range. Usage of this value is described in Section 4.1.
12.6. SDP Transport Protocol 12.6. SDP Transport Protocol
the SIP Control Framework defines the new SDP protocol field values The Channel Framework defines the new SDP protocol field values 'TCP/
'TCP/SCFW', 'TCP/TLS/SCFW', 'SCTP/SCFW' and 'SCTP/ TLS/SCFW", which CFW', 'TCP/TLS/CFW', 'SCTP/CFW' and 'SCTP/ TLS/CFW", which should be
should be registered in the sdp-parameters registry under "proto". registered in the sdp-parameters registry under "proto". The values
The values have the following meaning: have the following meaning:
o TCP/SCFW: Indicates the SIP Control Framework when TCP is used as o TCP/CFW: Indicates the SIP Channel Framework when TCP is used as
an underlying transport for the control channel. an underlying transport for the control channel.
o TCP/TLS/SCFW: Indicates the SIP Control Framework when TLS over
TCP is used as an underlying transport for the control channel. o TCP/TLS/CFW: Indicates the Channel Framework when TLS over TCP is
o SCTP/SCFW: Indicates the SIP Control Framework when SCTP is used used as an underlying transport for the control channel.
as an underlying transport for the control channel. o SCTP/CFW: Indicates the Channel Framework when SCTP is used as an
o SCTP/TLS/SCFW: Indicates the SIP Control Framework when TLS over underlying transport for the control channel.
SCTP is used as an underlying transport for the control channel. o SCTP/TLS/CFW: Indicates the Channel Framework when TLS over SCTP
is used as an underlying transport for the control channel.
Specifications defining new protocol values must define the rules for Specifications defining new protocol values must define the rules for
the associated media format namespace. The 'TCP/SCFW', 'TCP/TLS/ the associated media format namespace. The 'TCP/CFW', 'TCP/TLS/CFW',
SCFW', 'SCTP/SCFW' and 'SCTP/TLS/SCFW' protocol values allow only one 'SCTP/CFW' and 'SCTP/TLS/CFW' protocol values allow only one value in
value in the format field (fmt), which is a single occurrence of "*". the format field (fmt), which is a single occurrence of "*". Actual
Actual format determination is made using the control package format determination is made using the control package extension
extension specific payloads. specific payloads.
13. Changes 13. SDP Transport Protocol
Contact name: Chris Boulton cboulton@avaya.com.
Attribute name: "cfw-id".
Type of attribute Media level.
Subject to charset: Not.
Purpose of attribute: The 'cfw-id' attribute indicates
an identifier that can be used to correlate the control
channel with the SIP dialog used to negotiate it, when
the attribute value is used within the control channel.
Allowed attribute values: A token.
14. Changes
Note to RFC Editor: Please remove this whole section. Note to RFC Editor: Please remove this whole section.
13.1. Changes from 00 Version 14.1. Changes from 01 Version
o Aligned tokens to be 'SCFW' (removed ESCS). o Restructured text for readability.
o Changed SYNCH method name to SYNC.
o Removed 'pending' state to be replaced by 'update' with no
payload.
o Replaced construction of dialog-id with new SDP parameter and
revised text.
o Removed problem with K-Alive mechanism. K-Alive timers are now
separate from any other Control messages as the delay in
processing allows for un-sync on both sides.
o Added transaction timeout of 5 seconds - as per meeting.
o Added Upper Limit for transaction timeout on REPORT to 15 seconds.
o Added Content-Type to table and missing examples etc.
o Simplified Security Section as per meeting feedback.
o Added proposed 'holdconn' text.
o Added Default port text - as per meeting.
o Added Audit text.
14.2. Changes from 00 Version
o Aligned tokens to be 'CFW' (removed ESCS).
o Content-Length not mandatory for messages with no payload. o Content-Length not mandatory for messages with no payload.
o Corrected changes to call flows from legacy versions. o Corrected changes to call flows from legacy versions.
o Use of term 'Active UA' in section 7 + others. o Use of term 'Active UA' in section 7 + others.
o Added 'notify' to status header of ABNF. o Added 'notify' to status header of ABNF.
o Changed 481 to be transaction specific. o Changed 481 to be transaction specific.
o Added '423' duplicate transaction ID response. o Added '423' duplicate transaction ID response.
o Added '405' method not allowed. o Added '405' method not allowed.
o Added IANA section. o Added IANA section.
o Added Security Considerations section (used MSRP and MRCPv2 as a o Added Security Considerations section (used MSRP and MRCPv2 as a
template). template).
o Removed noisy initial REPORT message - *Lorenzo please check o Removed noisy initial REPORT message - *Lorenzo please check
text*. text*.
o Fixed ABNF - PLEASE CHECK. o Fixed ABNF - PLEASE CHECK.
o Removed separate event mechanism and now all tied to CONTROL o Removed separate event mechanism and now all tied to CONTROL
transaction (extended). transaction (extended).
o General scrub of text. o General scrub of text.
o Organised 'Editors Notes' for discussion on the mailing list. o Organised 'Editors Notes' for discussion on the mailing list.
o Fixed ABNF in relation to extra CRLF on Content-Type.
14. Contributors 15. Contributors
Asher Shiratzky from Radvision provided valuable support and Asher Shiratzky from Radvision provided valuable support and
contributions to the early versions of this document. contributions to the early versions of this document.
15. Acknowledgments 16. Acknowledgments
The authors would like to thank Ian Evans and Michael Bardzinski of The authors would like to thank Ian Evans and Michael Bardzinski of
Ubiquity Software, Adnan Saleem of Convedia, and Dave Morgan for Ubiquity Software, Adnan Saleem of Convedia, and Dave Morgan for
useful review and input to this work. Eric Burger contributed to the useful review and input to this work. Eric Burger contributed to the
early phases of this work. early phases of this work.
Expert review was also provided by Spencer Dawkins, Krishna Prasad Expert review was also provided by Spencer Dawkins, Krishna Prasad
Kalluri, Lorenzo Miniero, and Roni Even. Kalluri, Lorenzo Miniero, and Roni Even. Hadriel Kaplan provided
expert guidance on the dialog association mechanism. Lorenzo Miniero
has constantly provided excellent feedback based on his work.
16. Appendix A 17. Appendix A
During the creation of the Control Framework it has become clear that During the creation of the Control Framework it has become clear that
there are number of components that are common across multiple there are number of components that are common across multiple
packages. It has become apparent that it would be useful to collect packages. It has become apparent that it would be useful to collect
such re-usable components in a central location. In the short term such re-usable components in a central location. In the short term
this appendix provides the place holder for the utilities and it is this appendix provides the place holder for the utilities and it is
the intention that this section will eventually form the basis of an the intention that this section will eventually form the basis of an
initial 'Utilities Document' that can be used by Control Packages. initial 'Utilities Document' that can be used by Control Packages.
16.1. Common Dialog/Multiparty Reference Schema 17.1. Common Dialog/Multiparty Reference Schema
The following schema provides some common attributes for allowing The following schema provides some common attributes for allowing
Control Packages to apply specific commands to a particular SIP media Control Packages to apply specific commands to a particular SIP media
dialog (also referred to as Connection) or conference. If used dialog (also referred to as Connection) or conference. If used
within a Control Package the Connection and multiparty attributes within a Control Package the Connection and multiparty attributes
will be imported and used appropriately to specifically identify will be imported and used appropriately to specifically identify
either a SIP dialog or a conference instance. If used within a either a SIP dialog or a conference instance. If used within a
package, the value contained in the 'connection-id' attribute MUST be package, the value contained in the 'connectionid' attribute MUST be
constructed by concatenating the 'Local' and 'Remote' SIP dialog constructed by concatenating the 'Local' and 'Remote' SIP dialog
identifier tags as defined in RFC3261 [2]. They MUST then be identifier tags as defined in [RFC3261]. They MUST then be separated
separated using the '~' character. So the format would be: using the '~' character. So the format would be:
'Local Dialog tag' + '~' + 'Remote Dialog tag' 'Local Dialog tag' + '~' + 'Remote Dialog tag'
As an example, for an entity that has a SIP Local dialog identifier As an example, for an entity that has a SIP Local dialog identifier
of '7HDY839' and a Remote dialog identifier of 'HJKSkyHS', the of '7HDY839' and a Remote dialog identifier of 'HJKSkyHS', the
'connection-id' attribute for a Control Framework command would be: 'connectionid' attribute for a Control Framework command would be:
7HDY839~HJKSkyHS 7HDY839~HJKSkyHS
If a session description has more than one media description (as If a session description has more than one media description (as
identified by 'm=' in [9]) it is possible to explicitly reference identified by 'm=' in [RFC4566]) it is possible to explicitly
them individually. When constructing the 'connection-id' attribute reference them individually. When constructing the 'connectionid'
for a command that applies to a specific media ('m=') in an SDP attribute for a command that applies to a specific media ('m=') in an
description, an optional third component can be concatenated to the SDP description, an optional third component can be concatenated to
Connection reference key. It is again separated using the '~' the Connection reference key. It is again separated using the '~'
character and uses the 'label' attribute as specified in [10]. So character and uses the 'label' attribute as specified in [RFC4574].
the format would be: So the format would be:
'Local Dialog tag' + '~' + 'Remote Dialog tag' + '~' + 'Label Attribute' 'Local Dialog tag' + '~' + 'Remote Dialog tag' + '~' + 'Label Attribute'
As an example, for an entity that has a SIP Local dialog identifier As an example, for an entity that has a SIP Local dialog identifier
of '7HDY839', a Remote dialog identifier of 'HJKSkyHS' and an SDP of '7HDY839', a Remote dialog identifier of 'HJKSkyHS' and an SDP
label attribute of 'HUwkuh7ns', the 'connection-id' attribute for a label attribute of 'HUwkuh7ns', the 'connectionid' attribute for a
Control Framework command would be: Control Framework command would be:
7HDY839~HJKSkyHS~HUwkuh7ns 7HDY839~HJKSkyHS~HUwkuh7ns
It should be noted that Control Framework requests initiated in It should be noted that Control Framework requests initiated in
conjunction with a SIP dialog will produce a different conjunction with a SIP dialog will produce a different 'connectionid'
'connection-id' value depending on the directionality of the request, value depending on the directionality of the request, for example
for example Local and Remote tags are locally identifiable. Local and Remote tags are locally identifiable.
As with the Connection attribute previously defined, it is also As with the Connection attribute previously defined, it is also
useful to have the ability to apply specific control framework useful to have the ability to apply specific control framework
commands to a number of related dialogs, such as a multiparty call. commands to a number of related dialogs, such as a multiparty call.
This typically consists of a number of media dialogs that are This typically consists of a number of media dialogs that are
logically bound by a single identifier. The following schema allows logically bound by a single identifier. The following schema allows
for control framework commands to explicitly reference such a for control framework commands to explicitly reference such a
grouping through a 'conf' XML container. If used by a Control grouping through a 'conf' XML container. If used by a Control
Package, any control XML referenced by the attribute applies to all Package, any control XML referenced by the attribute applies to all
related media dialogs. Unlike the dialog attribute, the 'conf-id' related media dialogs. Unlike the dialog attribute, the
attribute does not need to be constructed based on the overlying SIP 'conferenceid' attribute does not need to be constructed based on the
dialog. The 'conf-id' attribute value is system specific and should overlying SIP dialog. The 'conferenceid' attribute value is system
be selected with relevant context and uniqueness. specific and should be selected with relevant context and uniqueness.
The full schema follows: The full schema follows:
<?xml version="1.0" encoding="UTF-8"?> <?xml version="1.0" encoding="UTF-8"?>
<xsd:schema targetNamespace="urn:ietf:params:xml:ns:control:framework-attributes" <xsd:schema targetNamespace="urn:ietf:params:xml:ns:control:framework-attributes"
xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsd="http://www.w3.org/2001/XMLSchema"
xmlns="urn:ietf:params:xml:ns::control:framework-attributes" xmlns="urn:ietf:params:xml:ns::control:framework-attributes"
elementFormDefault="qualified" attributeFormDefault="unqualified"> elementFormDefault="qualified" attributeFormDefault="unqualified">
<!--xsd:include schemaLocation="common-schema.xsd"/--> <!--xsd:include schemaLocation="common-schema.xsd"/-->
skipping to change at page 41, line 44 skipping to change at page 43, line 5
<xsd:documentation>SIP Connection and Conf Identifiers</xsd:documentation> <xsd:documentation>SIP Connection and Conf Identifiers</xsd:documentation>
</xsd:annotation> </xsd:annotation>
<xsd:attribute name="connectionid" type="xsd:string"/> <xsd:attribute name="connectionid" type="xsd:string"/>
<xsd:attribute name="conferenceid" type="xsd:string"/> <xsd:attribute name="conferenceid" type="xsd:string"/>
</xsd:attributeGroup> </xsd:attributeGroup>
</xsd:schema> </xsd:schema>
17. Normative References 18. Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement [I-D.ietf-sip-outbound]
Levels", BCP 14, RFC 2119, March 1997. Jennings, C. and R. Mahy, "Managing Client Initiated
Connections in the Session Initiation Protocol (SIP)",
draft-ietf-sip-outbound-13 (work in progress), March 2008.
[2] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP: Requirement Levels", BCP 14, RFC 2119, March 1997.
Session Initiation Protocol", RFC 3261, June 2002.
[3] Rosenberg, J. and H. Schulzrinne, "Reliability of Provisional [RFC2234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Responses in Session Initiation Protocol (SIP)", RFC 3262, Specifications: ABNF", RFC 2234, November 1997.
June 2002.
[4] Rosenberg, J. and H. Schulzrinne, "Session Initiation Protocol [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
(SIP): Locating SIP Servers", RFC 3263, June 2002. A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261,
June 2002.
[5] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model with [RFC3262] Rosenberg, J. and H. Schulzrinne, "Reliability of
Session Description Protocol (SDP)", RFC 3264, June 2002. Provisional Responses in Session Initiation Protocol
(SIP)", RFC 3262, June 2002.
[6] Yon, D. and G. Camarillo, "TCP-Based Media Transport in the [RFC3263] Rosenberg, J. and H. Schulzrinne, "Session Initiation
Session Description Protocol (SDP)", RFC 4145, September 2005. Protocol (SIP): Locating SIP Servers", RFC 3263,
June 2002.
[7] Groves, C., Pantaleo, M., Anderson, T., and T. Taylor, "Gateway [RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model
Control Protocol Version 1", RFC 3525, June 2003. with Session Description Protocol (SDP)", RFC 3264,
June 2002.
[8] Dolly, M. and R. Even, "Media Server Control Protocol [RFC3268] Chown, P., "Advanced Encryption Standard (AES)
Requirements", draft-dolly-mediactrl-requirements-00 (work in Ciphersuites for Transport Layer Security (TLS)",
progress), June 2007. RFC 3268, June 2002.
[9] Handley, M., "SDP: Session Description Protocol", [RFC3525] Groves, C., Pantaleo, M., Anderson, T., and T. Taylor,
draft-ietf-mmusic-sdp-new-26 (work in progress), January 2006. "Gateway Control Protocol Version 1", RFC 3525, June 2003.
[10] Levin, O. and G. Camarillo, "The Session Description Protocol [RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
(SDP) Label Attribute", RFC 4574, August 2006. Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, July 2003.
[11] Jennings, C. and R. Mahy, "Managing Client Initiated [RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
Connections in the Session Initiation Protocol (SIP)", 10646", STD 63, RFC 3629, November 2003.
draft-ietf-sip-outbound-11 (work in progress), November 2007.
[12] Rosenberg, J., Peterson, J., Schulzrinne, H., and G. Camarillo, [RFC3725] Rosenberg, J., Peterson, J., Schulzrinne, H., and G.
"Best Current Practices for Third Party Call Control (3pcc) in Camarillo, "Best Current Practices for Third Party Call
the Session Initiation Protocol (SIP)", BCP 85, RFC 3725, Control (3pcc) in the Session Initiation Protocol (SIP)",
April 2004. BCP 85, RFC 3725, April 2004.
[13] Rosenberg, J., Schulzrinne, H., and P. Kyzivat, "Indicating [RFC3840] Rosenberg, J., Schulzrinne, H., and P. Kyzivat,
User Agent Capabilities in the Session Initiation Protocol "Indicating User Agent Capabilities in the Session
(SIP)", RFC 3840, August 2004. Initiation Protocol (SIP)", RFC 3840, August 2004.
[14] Rosenberg, J., Schulzrinne, H., and P. Kyzivat, "Caller [RFC3841] Rosenberg, J., Schulzrinne, H., and P. Kyzivat, "Caller
Preferences for the Session Initiation Protocol (SIP)", Preferences for the Session Initiation Protocol (SIP)",
RFC 3841, August 2004. RFC 3841, August 2004.
[15] Schulzrinne, H., Casner, S., Frederick, R., and V. Jacobson, [RFC4145] Yon, D. and G. Camarillo, "TCP-Based Media Transport in
"RTP: A Transport Protocol for Real-Time Applications", STD 64, the Session Description Protocol (SDP)", RFC 4145,
RFC 3550, July 2003. September 2005.
[16] Yergeau, F., "UTF-8, a transformation format of ISO 10646", [RFC4366] Blake-Wilson, S., Nystrom, M., Hopwood, D., Mikkelsen, J.,
STD 63, RFC 3629, November 2003. and T. Wright, "Transport Layer Security (TLS)
Extensions", RFC 4366, April 2006.
[17] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax [RFC4474] Peterson, J. and C. Jennings, "Enhancements for
Specifications: ABNF", RFC 2234, November 1997. Authenticated Identity Management in the Session
Initiation Protocol (SIP)", RFC 4474, August 2006.
[18] Peterson, J. and C. Jennings, "Enhancements for Authenticated [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
Identity Management in the Session Initiation Protocol (SIP)", Description Protocol", RFC 4566, July 2006.
RFC 4474, August 2006.
[19] Blake-Wilson, S., Nystrom, M., Hopwood, D., Mikkelsen, J., and [RFC4574] Levin, O. and G. Camarillo, "The Session Description
T. Wright, "Transport Layer Security (TLS) Extensions", Protocol (SDP) Label Attribute", RFC 4574, August 2006.
RFC 4366, April 2006.
[20] Chown, P., "Advanced Encryption Standard (AES) Ciphersuites for [RFC5167] Dolly, M. and R. Even, "Media Server Control Protocol
Transport Layer Security (TLS)", RFC 3268, June 2002. Requirements", RFC 5167, March 2008.
[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008.
Authors' Addresses Authors' Addresses
Chris Boulton Chris Boulton
Avaya Avaya
Building 3 Building 3
Wern Fawr Lane Wern Fawr Lane
St Mellons St Mellons
Cardiff, South Wales CF3 5EA Cardiff, South Wales CF3 5EA
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attempt made to obtain a general license or permission for the use of attempt made to obtain a general license or permission for the use of
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specification can be obtained from the IETF on-line IPR repository at specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr. http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any The IETF invites any interested party to bring to its attention any
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Acknowledgment
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