CLUE Protocol Data Channel
draft-ietf-clue-datachannel-05

Abstract

This document defines how to use the WebRTC Data Channel mechanism in order to realize a data channel, referred to as a CLUE data channel, for transporting CLUE protocol messages between two CLUE entities.

The document defines how to describe the SCTPoDTLS association used to realize the CLUE data channel using SDP, and defines usage of two mechanisms for establishing a CLUE data channel: the Data Channel Establishment Protocol (DCEP) and the SDP-based "SCTP over DTLS" data channel negotiation mechanism.

Details and procedures associated with the CLUE protocol, and the SDP Offer/Answer procedures for negotiating usage of a CLUE data channel, are outside the scope of this document.

Status of This Memo

This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.

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This Internet-Draft will expire on May 31, 2015.

Copyright Notice

Copyright (c) 2014 IETF Trust and the persons identified as the document authors. All rights reserved.

This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.

Table of Contents

• 1. Introduction
• 2. Conventions
• 3. CLUE Data Channel
• 3.1. General
• 3.2. SDP Considerations
• 3.2.1. General
• 3.2.2. SDP dcpmap Attribute
• 3.2.3. SDP dcsa Attribute
• 3.2.4. Example
• 3.3. DCEP Considerations
• 3.3.1. General
• 3.3.2. Open CLUE Data Channel
• 3.3.3. Close CLUE Data Channel
• 3.4. SCTP Considerations
• 3.4.1. SCTP Payload Protocol Identifier (PPID)
• 3.4.2. Reliability
• 3.4.3. Order
• 3.4.4. Stream Reset
• 3.4.5. SCTP Multihoming
• 4. Security Considerations
• 5. IANA Considerations
• 5.1. New WebRTC Data Channel Protocol Value
• 5.2. New SDP dcmap attribute subprotocol value
• 6. Acknowledgments
• 7. Change Log
• 8. References
• 8.1. Normative References
• 8.2. Informative References
• Author's Address

1. Introduction

This document defines how to use the WebRTC Data Channel mechanism [I-D.ietf-rtcweb-data-channel] in order to realize a data channel, referred to as a CLUE data channel, for transporting CLUE protocol messages between two CLUE entities.

The document defines how to describe the SCTPoDTLS association [I-D.ietf-tsvwg-sctp-dtls-encaps] used to realize the CLUE data channel using SDP, and defines usage of two mechanisms for establishing a CLUE data channel: the Data Channel Establishment Protocol (DCEP) [I-D.ietf-rtcweb-data-protocol] and the SDP-based "SCTP over DTLS" data channel negotiation mechanism [I-D.ejzak-mmusic-data-channel-sdpneg]. This includes SCTP considerations specific to a CLUE data channel, the SDP Media Description (m- line) values, usage of SDP attributes and DCEP considerations (when DCEP is used) specific to a CLUE data channel.

Details and procedures associated with the CLUE protocol, and the SDP Offer/Answer [RFC3264] procedures for negotiating usage of a CLUE data channel, are outside the scope of this document.

Simultaneous usage of DCEP and the SDP-based "SCTP over DTLS" data channel negotiation mechanism for opening a CLUE data channel is outside the scope of this specification.

2. Conventions

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14, RFC 2119 [RFC2119].

WebRTC Data Channel refers to a SCTPoDTLS association [I-D.ietf-tsvwg-sctp-dtls-encaps] that is used to transport non-media data between two entities, according to the procedures in [I-D.ietf-rtcweb-data-channel].

CLUE data channel refers to a WebRTC Data Channel [I-D.ietf-rtcweb-data-channel] realization, with a specific set of SCTP characteristics, with the purpose of transporting CLUE protocol [I-D.ietf-clue-protocol] messages between two CLUE entities.

CLUE entity refers to a SIP User Agent (UA) [RFC3261] that supports the CLUE data channel and the CLUE protocol.

CLUE session refers to a SIP session [RFC3261] between to SIP UAs, where a CLUE data channel, associated with the SIP session, has been established between the SIP UAs.

[RFC4960] defines an SCTP stream as a unidirectional logical channel established from one to another associated SCTP endpoint, within which all user messages are delivered in sequence except for those submitted to the unordered delivery service.

[RFC4960] defines an SCTP identifier as a unsigned integer, which identifies a SCTP stream.

3. CLUE Data Channel

3.1. General

This section describes the realization of a CLUE Data Channel. This includes a set of SCTP characteristics specific to a CLUE Data Channel, the values of the m- line describing the SCTPoDTLS association associated with the WEBRTC Data Channel, and the usage of either DCEP or SDP-based "SCTP over DTLS" data channel negotiation mechanism for creating the CLUE Data Channel.

As described in [I-D.ietf-rtcweb-data-channel], the SCTP streams realizing a WebRTC Data Channel must be associated with the same SCTP association. In addition, both SCTP streams realizing the WebRTC Data Channel must use the same SCTP stream identifier value. These rules also apply to a CLUE Data Channel.

Within a given CLUE session, a CLUE entity MUST use a single CLUE Data Channel for transport of all CLUE messages towards its peer.

3.2. SDP Considerations

3.2.1. General

This section defines how to construct the SDP Media Description (m- line) for describing the SCTPoDTLS association used to realize a WebRTC Data Channel. The section also defines how to construct the SDP dcmap attribute, when the SDP-based "SCTP over DTLS" data channel negotiation mechanism is used for establishing a CLUE Data Channel on the SCTPoDTLS association.

NOTE: Other protocols than SDP for negotiating usage of a SCTPoDTLS association for realizing a WebRTC Data Channel are outside the scope of this specification.

[I-D.ietf-clue-signaling] describes the SDP Offer/Answer procedures for negotiating a CLUE session, including the CLUE controlled media streams and the CLUE Data Channel.

3.2.1.1. SDP Media Description Fields

As defined in [I-D.ietf-mmusic-sctp-sdp], the field values of an m- line describing an SCTPoDTLS association are set as following:

							
		m=application 54111 DTLS/SCTP webrtc-datachannel
		a=dcmap:2 subprotocol="CLUE"

           				

	Subprotocl Identifier:		CLUE
	Subprotocol Common Name:	CLUE
	Subprotocol Definition:		RFC-XXXX