draft-ietf-mmusic-sctp-sdp-21.txt   draft-ietf-mmusic-sctp-sdp-22.txt 
MMUSIC C. Holmberg MMUSIC C. Holmberg
Internet-Draft Ericsson Internet-Draft Ericsson
Intended status: Standards Track R. Shpount Intended status: Standards Track R. Shpount
Expires: July 13, 2017 TurboBridge Expires: July 29, 2017 TurboBridge
S. Loreto S. Loreto
G. Camarillo G. Camarillo
Ericsson Ericsson
January 9, 2017 January 25, 2017
Session Description Protocol (SDP) Offer/Answer Procedures For Stream Session Description Protocol (SDP) Offer/Answer Procedures For Stream
Control Transmission Protocol (SCTP) over Datagram Transport Layer Control Transmission Protocol (SCTP) over Datagram Transport Layer
Security (DTLS) Transport. Security (DTLS) Transport.
draft-ietf-mmusic-sctp-sdp-21 draft-ietf-mmusic-sctp-sdp-22
Abstract Abstract
The Stream Control Transmission Protocol (SCTP) is a transport The Stream Control Transmission Protocol (SCTP) is a transport
protocol used to establish associations between two endpoints. protocol used to establish associations between two endpoints.
draft-ietf-tsvwg-sctp-dtls-encaps-09 specifies how SCTP can be used draft-ietf-tsvwg-sctp-dtls-encaps-09 specifies how SCTP can be used
on top of the Datagram Transport Layer Security (DTLS) protocol, on top of the Datagram Transport Layer Security (DTLS) protocol,
referred to as SCTP-over-DTLS. referred to as SCTP-over-DTLS.
This specification defines the following new Session Description This specification defines the following new Session Description
skipping to change at page 1, line 46 skipping to change at page 1, line 46
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on July 13, 2017. This Internet-Draft will expire on July 29, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 24 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 24
1. Introduction 1. Introduction
SDP (Session Description Protocol) [RFC4566] provides a general- SDP (Session Description Protocol) [RFC4566] provides a general-
purpose format for describing multimedia sessions in announcements or purpose format for describing multimedia sessions in announcements or
invitations. TCP-Based Media Transport in the Session Description invitations. TCP-Based Media Transport in the Session Description
Protocol (SDP) [RFC4145] specifies a general mechanism for describing Protocol (SDP) [RFC4145] specifies a general mechanism for describing
and establishing TCP [RFC0793] streams. Connection-Oriented Media and establishing TCP [RFC0793] streams. Connection-Oriented Media
Transport over the Transport Layer Security (TLS) Protocol in SDP Transport over the Transport Layer Security (TLS) Protocol in SDP
[RFC4572] extends RFC4145 [RFC4145] for describing TCP-based media [I-D.ietf-mmusic-4572-update] extends RFC4145 [RFC4145] for
streams that are protected using TLS. describing TCP-based media streams that are protected using TLS.
The Stream Control Transmission Protocol (SCTP) [RFC4960] is a The Stream Control Transmission Protocol (SCTP) [RFC4960] is a
transport protocol used to establish associations between two reliable transport protocol used to transport data between two
endpoints. endpoints using SCTP associations.
[I-D.ietf-tsvwg-sctp-dtls-encaps] specifies how SCTP can be used on [I-D.ietf-tsvwg-sctp-dtls-encaps] specifies how SCTP can be used on
top of the Datagram Transport Layer Security (DTLS) protocol, top of the Datagram Transport Layer Security (DTLS) protocol,
referred to as SCTP-over-DTLS. referred to as SCTP-over-DTLS.
This specification defines the following new Session Description This specification defines the following new Session Description
Protocol (SDP) [RFC4566] protocol identifiers (proto Protocol (SDP) [RFC4566] protocol identifiers (proto
values):'UDP/DTLS/SCTP' and 'TCP/DTLS/SCTP'. This specification also values):'UDP/DTLS/SCTP' and 'TCP/DTLS/SCTP'. This specification also
specifies how to use the new proto values with the SDP Offer/Answer specifies how to use the new proto values with the SDP Offer/Answer
mechanism [RFC3264] for negotiating SCTP-over-DTLS associations. mechanism [RFC3264] for negotiating SCTP-over-DTLS associations.
NOTE: Due to the characteristics of TCP, usage of 'TCP/DTLS/SCTP' NOTE: Due to the characteristics of TCP, usage of 'TCP/DTLS/SCTP'
will always force ordered and reliable delivery of the SCTP packets, will always force ordered and reliable delivery of the SCTP packets,
which limits the usage of the SCTP options. Therefore, it is which limits the usage of the SCTP options. Therefore, it is
strongly RECOMMENDED that TCP is only used in situations where UDP RECOMMENDED that TCP is only used in situations where UDP traffic is
traffic is blocked. blocked.
2. Conventions 2. Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
3. SCTP Terminology 3. SCTP Terminology
SCTP Association: A protocol relationship between SCTP endpoints, SCTP Association: A protocol relationship between SCTP endpoints,
skipping to change at page 4, line 44 skipping to change at page 4, line 44
4. SDP Media Descriptions 4. SDP Media Descriptions
4.1. General 4.1. General
This section defines the following new SDP Media Description (m- This section defines the following new SDP Media Description (m-
line) protocol identifiers (proto values) for describing an SCTP line) protocol identifiers (proto values) for describing an SCTP
association: 'UDP/DTLS/SCTP' and 'TCP/DTLS/SCTP'. The section also association: 'UDP/DTLS/SCTP' and 'TCP/DTLS/SCTP'. The section also
describes how an m- line, associated with the proto values, is describes how an m- line, associated with the proto values, is
created. created.
The following is the format for an 'm' line, as specified in RFC4566 The following is the format for an m- line, as specified in RFC4566
[RFC4566]: [RFC4566]:
m=<media> <port> <proto> <fmt> ... m=<media> <port> <proto> <fmt> ...
The 'UDP/DTLS/SCTP' and 'TCP/DTLS/SCTP' proto values are similar to The 'UDP/DTLS/SCTP' and 'TCP/DTLS/SCTP' proto values are similar to
both the 'UDP' and 'TCP' proto values in that they only describe the both the 'UDP' and 'TCP' proto values in that they only describe the
transport-layer protocol and not the upper-layer protocol. transport-layer protocol and not the upper-layer protocol.
NOTE: When the 'UDP/DTLS/SCTP' and 'TCP/DTLS/SCTP' proto values are NOTE: When the 'UDP/DTLS/SCTP' and 'TCP/DTLS/SCTP' proto values are
used, the underlying transport protocol is respectively UDP and TCP; used, the underlying transport protocol is respectively UDP and TCP;
SCTP is carried on top of DTLS which is on top of those transport- SCTP is carried on top of DTLS which is on top of those transport-
layer protocols. layer protocols.
The m- line fmt value, identifying the application-layer protocol,
MUST be registered by IANA.
4.2. Protocol Identifiers 4.2. Protocol Identifiers
The new proto values are defined as below: The new proto values are defined as below:
o The 'UDP/DTLS/SCTP' proto value describes an SCTP association on o The 'UDP/DTLS/SCTP' proto value describes an SCTP association on
top of a DTLS association on top of UDP, as defined in Section 7. top of a DTLS association on top of UDP, as defined in Section 7.
o The 'TCP/DTLS/SCTP' proto value describes an SCTP association on o The 'TCP/DTLS/SCTP' proto value describes an SCTP association on
top of a DTLS association on top of TCP, as defined in Section 8. top of a DTLS association on top of TCP, as defined in Section 8.
4.3. Media Format Management 4.3. Media Format Management
[RFC4566] defines that specifications defining new proto values must [RFC4566] defines that specifications defining new proto values must
define the rules by which their media format (fmt) namespace is define the rules by which their media format (fmt) namespace is
managed. managed.
An m- line with a proto value of 'UDP/DTLS/SCTP' or 'TCP/DTLS/SCTP' An m- line with a proto value of 'UDP/DTLS/SCTP' or 'TCP/DTLS/SCTP'
always describes a single SCTP association. always describes a single SCTP association.
In addition, such m- line MUST further indicate the application-layer In addition, such m- line MUST further indicate the application-layer
protocol using an 'fmt' identifier. There MUST be exactly one 'fmt' protocol using an 'fmt' identifier. There MUST be exactly one fmt
value per m- line associated with the proto values defined in this value per m- line associated with the proto values defined in this
specification. The "fmt" namespace associated with those proto specification. The 'fmt' namespace associated with those proto
values describes the generic application usage of the entire SCTP values describes the generic application usage of the entire SCTP
association, including the associated SCTP streams. association, including the associated SCTP streams.
Section 15.3 defines the IANA registry for the media format When the 'UDP/DTLS/SCTP' and 'TCP/DTLS/SCTP' proto values, the m-
namespace. line fmt value, identifying the application-layer protocol, MUST be
registered by IANA. Section 15.3 defines the IANA registry for the
media format namespace.
NOTE: A mechanism on how to describe, and manage, individual SCTP NOTE: A mechanism on how to describe, and manage, individual SCTP
streams within an SCTP association, is outside the scope of this streams within an SCTP association, is outside the scope of this
specification. [I-D.ietf-mmusic-data-channel-sdpneg] defines a specification. [I-D.ietf-mmusic-data-channel-sdpneg] defines a
mechanism for negotiating individual SCTP streams used to realize mechanism for negotiating individual SCTP streams used to realize
WebRTC data channels [I-D.ietf-rtcweb-data-channel]. WebRTC data channels [I-D.ietf-rtcweb-data-channel].
4.4. Syntax 4.4. Syntax
4.4.1. General 4.4.1. General
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<proto>: "UDP/DTLS/SCTP" or "TCP/DTLS/SCTP" <proto>: "UDP/DTLS/SCTP" or "TCP/DTLS/SCTP"
<port>: UDP port number (for "UDP/DTLS/SCTP") <port>: UDP port number (for "UDP/DTLS/SCTP")
TCP port number (for ""UDP/DTLS/SCTP") TCP port number (for ""UDP/DTLS/SCTP")
<fmt>: a string denoting the association-usage, <fmt>: a string denoting the association-usage,
limited to the syntax of a 'token' as limited to the syntax of a 'token' as
defined in RFC4566. defined in RFC4566.
4.5. Example 4.5. Example
m=application 12345 UDP/DTLS/SCTP webrtc-datachannel m=application 12345 UDP/DTLS/SCTP webrtc-datachannel
a=sctp-port:5000
a=max-message-size:100000 a=max-message-size:100000
NOTE: 'webrtc-datachannel' indicates the WebRTC Data Channel NOTE: 'webrtc-datachannel' indicates the WebRTC Data Channel
Establishment Protocol defined in [I-D.ietf-rtcweb-data-protocol]. Establishment Protocol defined in [I-D.ietf-rtcweb-data-protocol].
5. SDP 'sctp-port' Attribute 5. SDP 'sctp-port' Attribute
5.1. General 5.1. General
This section defines a new SDP media-level attribute, 'sctp-port'. This section defines a new SDP media-level attribute, 'sctp-port'.
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5.2. Syntax 5.2. Syntax
[RFC EDITOR NOTE: Please replace RFCXXXX with the RFC number of this [RFC EDITOR NOTE: Please replace RFCXXXX with the RFC number of this
document.] document.]
The definition of the SDP 'sctp-port' attribute is: The definition of the SDP 'sctp-port' attribute is:
Attribute name: sctp-port Attribute name: sctp-port
Type of attribute: media Type of attribute: media
Mux category: SPECIAL Mux category: CAUTION
Subject to charset: No Subject to charset: No
Purpose: Indicate the SCTP port value associated with Purpose: Indicate the SCTP port value associated with
the SDP Media Description. the SDP Media Description.
Appropriate values: Integer Appropriate values: Integer
Contact name: Christer Holmberg Contact name: Christer Holmberg
Contact e-mail: christer.holmberg@ericsson.com Contact e-mail: christer.holmberg@ericsson.com
Reference: RFCXXXX Reference: RFCXXXX
Syntax: Syntax:
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The SCTP port range is between 0 and 65535 (both included). The SCTP port range is between 0 and 65535 (both included).
Leading zeroes MUST NOT be used. Leading zeroes MUST NOT be used.
Example: Example:
a=sctp-port:5000 a=sctp-port:5000
5.3. Mux Category 5.3. Mux Category
The mux category [I-D.ietf-mmusic-sdp-mux-attributes] for the SDP The mux category [I-D.ietf-mmusic-sdp-mux-attributes] for the SDP
'sctp-port' attribute is SPECIAL. 'sctp-port' attribute is CAUTION.
As the usage of multiple SCTP associations on top of a single DTLS As the usage of multiple SCTP associations on top of a single DTLS
association is outside the scope of this specification, no mux rules association is outside the scope of this specification, no mux rules
are specified for the 'UDP/DTLS/SCTP' and 'TCP/DTLS/SCTP' proto are specified for the 'UDP/DTLS/SCTP' and 'TCP/DTLS/SCTP' proto
values. Future extensions, that define how to negotiate multiplexing values. Future extensions, that define how to negotiate multiplexing
of multiple SCTP associations of top of a single DTLS association, of multiple SCTP associations of top of a single DTLS association,
need to also define the mux rules for the attribute. need to also define the mux rules for the attribute.
6. SDP 'max-message-size' Attribute 6. SDP 'max-message-size' Attribute
6.1. General 6.1. General
This section defines a new SDP media-level attribute, 'max-message- This section defines a new SDP media-level attribute, 'max-message-
size'. The attribute can be associated with an m- line to indicate size'. The attribute can be associated with an m- line to indicate
the maximum SCTP user message size (indicated in bytes) that an SCTP the maximum SCTP user message size (indicated in bytes) that an SCTP
endpoint is willing to receive on the SCTP association associated endpoint is willing to receive on the SCTP association associated
with the m- line. Different attribute values can be used in each with the m- line. Different attribute values can be used in each
direction. direction.
An SCTP endpoint MUST assume that larger SCTP user message sizes will An SCTP endpoint MUST NOT send a SCTP user message with a message
be rejected by the peer SCTP endpoint. SCTP endpoints need to decide size that is larger than the maximum size indicated by the peer, as
on appropriate behavior in case a message needs to be sent in which it cannot be assumed that the peer would accept such message.
the SCTP user message size exceeds thevmaximum SCTP user message
size.
If the SDP 'max-message-size' attribute contains a maximum message If the SDP 'max-message-size' attribute contains a maximum message
size value of zero, it indicates the SCTP endpoint will handle size value of zero, it indicates the SCTP endpoint will handle
messages of any size, subject to memory capacity etc. messages of any size, subject to memory capacity etc.
If the SDP 'max-message-size' attribute is not present, the default If the SDP 'max-message-size' attribute is not present, the default
value is 64K. value is 64K.
NOTE: This specification only defines the usage of the SDP 'max- NOTE: This specification only defines the usage of the SDP 'max-
message-size' attribute when associated with an m- line containing message-size' attribute when associated with an m- line containing
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SCTP'. Usage of the attribute with other proto values needs to be SCTP'. Usage of the attribute with other proto values needs to be
defined in a separate specification. defined in a separate specification.
6.2. Syntax 6.2. Syntax
[RFC EDITOR NOTE: Please replace RFCXXXX with the RFC number of this [RFC EDITOR NOTE: Please replace RFCXXXX with the RFC number of this
document.] document.]
The definition of the SDP 'max-message-size' attribute is: The definition of the SDP 'max-message-size' attribute is:
Attribute name: max-message-size Attribute name: max-message-size
Type of attribute: media Type of attribute: media
Mux category: SPECIAL Mux category: CAUTION
Subject to charset: No Subject to charset: No
Purpose: Indicate the maximum message size that Purpose: Indicate the maximum message size
an SCTP endpoint is willing to receive (indicated in bytes) that an SCTP
on the SCTP association associated endpoint is willing to receive on the
with the SDP Media Description. SCTP association associated with the SDP
Appropriate values: Integer Media Description.
Contact name: Christer Holmberg Appropriate values: Integer
Contact e-mail: christer.holmberg@ericsson.com Contact name: Christer Holmberg
Reference: RFCXXXX Contact e-mail: christer.holmberg@ericsson.com
Reference: RFCXXXX
Syntax: Syntax:
max-message-size-value = 1*<DIGIT defined in RFC4566> max-message-size-value = 1*<DIGIT defined in RFC4566>
Leading zeroes MUST NOT be used. Leading zeroes MUST NOT be used.
Example: Example:
a=max-message-size:100000 a=max-message-size:100000
6.3. Mux Category 6.3. Mux Category
The mux category for the SDP 'max-message-size' attribute is SPECIAL. The mux category for the SDP 'max-message-size' attribute is CAUTION.
As the usage of multiple SCTP associations on top of a single DTLS As the usage of multiple SCTP associations on top of a single DTLS
association is outside the scope of this specification, no mux rules association is outside the scope of this specification, no mux rules
are specified for the 'UDP/DTLS/SCTP' and 'TCP/DTLS/SCTP' proto are specified for the 'UDP/DTLS/SCTP' and 'TCP/DTLS/SCTP' proto
values. values.
7. UDP/DTLS/SCTP Transport Realization 7. UDP/DTLS/SCTP Transport Realization
The UDP/DTLS/SCTP transport is realized as described below: The UDP/DTLS/SCTP transport is realized as described below:
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NOTE: DTLS on top of TCP, without using the framing method defined in NOTE: DTLS on top of TCP, without using the framing method defined in
[RFC4571] is outside the scope of this specification. A separate [RFC4571] is outside the scope of this specification. A separate
proto value would need to be registered for such transport proto value would need to be registered for such transport
realization. realization.
9. Association And Connection Management 9. Association And Connection Management
9.1. General 9.1. General
This section describes how to mange an SCTP association, DTLS This section describes how to manage an SCTP association, DTLS
association and TCP connection using SDP attributes. association and TCP connection using SDP attributes.
The SCTP association, the DTLS association and the TCP connection are The SCTP association, the DTLS association and the TCP connection are
managed independently from each other. Each can be established and managed independently from each other. Each can be established and
closed without impacting others. closed without impacting others.
The detailed SDP Offer/Answer [RFC3264] procedures for the SDP The detailed SDP Offer/Answer [RFC3264] procedures for the SDP
attributes are described in Section 10. attributes are described in Section 10.
9.2. SDP sendrecv/sendonly/recvonly/inactive Attribute 9.2. SDP sendrecv/sendonly/recvonly/inactive Attribute
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association can be established using the procedures in this section association can be established using the procedures in this section
for establishing an SCTP association. for establishing an SCTP association.
SCTP associations might be closed without SDP signalling, e.g, in SCTP associations might be closed without SDP signalling, e.g, in
case of a failure. The procedures in this section MUST be followed case of a failure. The procedures in this section MUST be followed
to establish a new SCTP association. This requires a new SDP Offer/ to establish a new SCTP association. This requires a new SDP Offer/
Answer exchange. New (different than the ones currently used) SCTP Answer exchange. New (different than the ones currently used) SCTP
ports MUST be used by both endpoints. ports MUST be used by both endpoints.
NOTE: Closing and establishing a new SCTP association using the SDP NOTE: Closing and establishing a new SCTP association using the SDP
'sctp-port' attribute will not impact the underlying DTLS 'sctp-port' attribute will not affect the state of the underlying
association. DTLS association.
9.4. DTLS Association (UDP/DTLS/SCTP And TCP/DTLS/SCTP) 9.4. DTLS Association (UDP/DTLS/SCTP And TCP/DTLS/SCTP)
A DTLS association is managed according to the procedures in A DTLS association is managed according to the procedures in
[I-D.ietf-mmusic-dtls-sdp]. Hence, the SDP 'setup' attribute is used [I-D.ietf-mmusic-dtls-sdp]. Hence, the SDP 'setup' attribute is used
to negotiate the (D)TLS roles ('client' and 'server') [RFC4572]. to negotiate the (D)TLS roles ('client' and 'server')
[I-D.ietf-mmusic-4572-update].
NOTE: The SDP 'setup' attribute is used to negotiate both the DTLS NOTE: The SDP 'setup' attribute is used to negotiate both the DTLS
roles and the TCP roles (Section 9.5). roles and the TCP roles (Section 9.5).
NOTE: As described in [RFC5245], if the Interactive Connectivity NOTE: As described in [RFC5245], if the Interactive Connectivity
Establishment (ICE) mechanism [RFC5245] is used, all ICE candidates Establishment (ICE) mechanism [RFC5245] is used, all ICE candidates
associated with a DTLS association are considered part of the same associated with a DTLS association are considered part of the same
DTLS association. Thus, a switch from one candidate pair to another DTLS association. Thus, a switch from one candidate pair to another
candidate pair will not trigger the establishment of a new DTLS candidate pair will not trigger the establishment of a new DTLS
association. association.
skipping to change at page 13, line 25 skipping to change at page 13, line 25
o MAY associate an SDP 'max-message-size' attribute [Section 6] with o MAY associate an SDP 'max-message-size' attribute [Section 6] with
the m- line. the m- line.
10.3. Generating the SDP Answer 10.3. Generating the SDP Answer
When the answerer receives an offer, which contains an m- line When the answerer receives an offer, which contains an m- line
describing an SCTP-over-DTLS association, if the answerer accepts the describing an SCTP-over-DTLS association, if the answerer accepts the
association, the answerer: association, the answerer:
o MUST insert a corresponding m- line in the answer, with an o MUST insert a corresponding m- line in the answer, with an m- line
identical m- line proto value [RFC3264]; proto value [RFC3264] identical to the value in the offer;
o MUST associate an SDP 'setup' attribute with the m- line; o MUST associate an SDP 'setup' attribute with the m- line;
o MUST associate an SDP 'sctp-port' attribute with the m- line. If o MUST associate an SDP 'sctp-port' attribute with the m- line. If
the offer contained a new (different than the one currently used) the offer contained a new (different than the one currently used)
SCTP port value the answerer MUST also associate a new SCTP port SCTP port value the answerer MUST also associate a new SCTP port
value. If the offer contained a zero SCTP port value, or if the value. If the offer contained a zero SCTP port value, or if the
answerer does not accept the SCTP association, the answerer MUST answerer does not accept the SCTP association, the answerer MUST
also associate a zero SCTP port value; and also associate a zero SCTP port value; and
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o MUST, in the case of TCP/DTLS/SCTP, if a TCP connection has not o MUST, in the case of TCP/DTLS/SCTP, if a TCP connection has not
yet been established, or if an existing TCP connection is to be yet been established, or if an existing TCP connection is to be
closed and replaced by a new TCP connection, follow the procedures closed and replaced by a new TCP connection, follow the procedures
in [RFC4145] for closing and establishing a TCP connection; in [RFC4145] for closing and establishing a TCP connection;
o MUST, if a DTLS association has not yet been established, or if an o MUST, if a DTLS association has not yet been established, or if an
existing DTLS association is to be closed and replaced by a new existing DTLS association is to be closed and replaced by a new
DTLS association, follow the procedures in DTLS association, follow the procedures in
[I-D.ietf-mmusic-dtls-sdp] for closing establishing a DTLS [I-D.ietf-mmusic-dtls-sdp] for closing the currently used, and
association; and establishing a new, DTLS association; and
o MUST, if an SCTP association has not yet been established, or if o MUST, if an SCTP association has not yet been established, or if
an existing SCTP association is to be closed and replaced by a new an existing SCTP association is to be closed and replaced by a new
SCTP association, initiate the closing of the existing SCTP SCTP association, initiate the closing of the existing SCTP
association (if applicable) and establishment of the SCTP association (if applicable) and establishment of the SCTP
association. association.
If the SDP 'sctp-port' attribute in the answer contains a zero If the SDP 'sctp-port' attribute in the answer contains a zero
attribute value, the answerer MUST NOT establish an SCTP association. attribute value, the answerer MUST NOT establish an SCTP association.
If an SCTP association exists, the offerer MUST close it. If an SCTP association exists, the offerer MUST close it.
skipping to change at page 15, line 48 skipping to change at page 15, line 48
the underlying DTLS association (and the underlying TCP connection the underlying DTLS association (and the underlying TCP connection
in case of TCP/DTLS/SCTP) it MUST assign a zero port value to the in case of TCP/DTLS/SCTP) it MUST assign a zero port value to the
m- line associated with the SCTP and DTLS associations (and TCP m- line associated with the SCTP and DTLS associations (and TCP
connection in case of TCP/DTLS/SCTP), following the procedures in connection in case of TCP/DTLS/SCTP), following the procedures in
[RFC3264]. [RFC3264].
o NOTE: This specification does not define a mechanism for o NOTE: This specification does not define a mechanism for
explicitly closing a DTLS association while maintaining the explicitly closing a DTLS association while maintaining the
overlying SCTP association. However, if a DTLS association is overlying SCTP association. However, if a DTLS association is
closed and replaced with a new DTLS association, as a result of closed and replaced with a new DTLS association, as a result of
some other action [I-D.ietf-mmusic-dtls-sdp], the SCTP association some other action [I-D.ietf-mmusic-dtls-sdp], the state of the
is not affected. SCTP association is not affected.
The offer follows the procedures in [I-D.ietf-mmusic-dtls-sdp] The offer follows the procedures in [I-D.ietf-mmusic-dtls-sdp]
regarding the DTLS association impacts when modifying a session. regarding the DTLS association impacts when modifying a session.
In the case of TCP/DTLS/SCTP, the offerer follows the procedures in In the case of TCP/DTLS/SCTP, the offerer follows the procedures in
[RFC4145] regarding the TCP connection impacts when modifying a [RFC4145] regarding the TCP connection impacts when modifying a
session. session.
11. Multihoming Considerations 11. Multihoming Considerations
skipping to change at page 18, line 8 skipping to change at page 18, line 8
a=sctp-port:6000 a=sctp-port:6000
a=max-message-size:100000 a=max-message-size:100000
- The answerer UDP port value is 64300. - The answerer UDP port value is 64300.
- The answerer SCTP port value is 6000. - The answerer SCTP port value is 6000.
- The answerer takes the server DTLS role. - The answerer takes the server DTLS role.
14. Security Considerations 14. Security Considerations
[RFC4566] defines general SDP security considerations, while [RFC4566] defines general SDP security considerations, while
[RFC3264], [RFC4145] and [RFC4572] define security considerations [RFC3264], [RFC4145] and [I-D.ietf-mmusic-4572-update] define
when using the SDP offer/answer mechanism to negotiate media streams. security considerations when using the SDP offer/answer mechanism to
negotiate media streams.
[RFC4960] defines general SCTP security considerations and [RFC4960] defines general SCTP security considerations and
[I-D.ietf-tsvwg-sctp-dtls-encaps] defines security considerations [I-D.ietf-tsvwg-sctp-dtls-encaps] defines security considerations
when using SCTP on top of DTLS. when using SCTP on top of DTLS.
This specification does not introduce new security considerations in This specification does not introduce new security considerations in
addition to those defined in the specifications listed above. addition to those defined in the specifications listed above.
15. IANA Considerations 15. IANA Considerations
skipping to change at page 19, line 11 skipping to change at page 19, line 11
This document defines a new SDP media-level attribute,'max-message- This document defines a new SDP media-level attribute,'max-message-
size'. The details of the attribute are defined in Section 6.2. size'. The details of the attribute are defined in Section 6.2.
15.3. association-usage Name Registry 15.3. association-usage Name Registry
[RFC EDITOR NOTE: Please replace RFCXXXX with the RFC number of this [RFC EDITOR NOTE: Please replace RFCXXXX with the RFC number of this
document.] document.]
This specification creates a new IANA registry, following the This specification creates a new IANA registry, following the
procedures in [RFC5226], for the "fmt" namespace associated with the procedures in [RFC5226], for the namespace associated with the
'UDP/DTLS/SCTP' and 'TCP/DTLS/SCTP' protocol identifiers. Each "fmt" 'UDP/DTLS/SCTP' and 'TCP/DTLS/SCTP' protocol identifiers. Each fmt
value describes the usage of an entire SCTP association, including value describes the usage of an entire SCTP association, including
all SCTP streams associated with the SCTP association. all SCTP streams associated with the SCTP association.
NOTE: Usage indication of individual SCTP streams is outside the NOTE: Usage indication of individual SCTP streams is outside the
scope of this specification. scope of this specification.
The "fmt" value, "association-usage", used with these "proto" values The fmt value, "association-usage", used with these "proto" values is
is required. It is defined in Section 4. required. It is defined in Section 4.
As part of this registry, IANA maintains the following information: As part of this registry, IANA maintains the following information:
association-usage name: The identifier of the subprotocol, as will association-usage name: The identifier of the subprotocol, as will
be used as the "fmt" value. be used as the fmt value.
association-usage reference: A reference to the document in which association-usage reference: A reference to the document in which
the association-usage is defined. the association-usage is defined.
association-usage names are to be subject to the "First Come First association-usage names are to be subject to the "First Come First
Served" IANA registration policy [RFC5226]. Served" IANA registration policy [RFC5226].
IANA is asked to add initial values to the registry. IANA is asked to add initial values to the registry.
|----------------------------------------------------------| |----------------------------------------------------------|
| name | Reference | | name | Reference |
|----------------------------------------------------------| |----------------------------------------------------------|
| webrtc-datachannel | draft-ietf-rtcweb-data-protocol-xx, | | webrtc-datachannel | draft-ietf-rtcweb-data-protocol-xx, |
| | RFCXXX | | | RFCXXX |
|----------------------------------------------------------| |----------------------------------------------------------|
[RFC EDITOR NOTE: Please hold the publication of this draft [RFC EDITOR NOTE: Please hold the publication of this draft
until draft-ietf-rtcweb-data-protocol has been published as an RFC. until draft-ietf-rtcweb-data-protocol has been published as an RFC.
Then, replace the reference to draft-ietf-rtcweb-data-protocol Then, replace the reference to draft-ietf-rtcweb-data-protocol
with the RFC number.] with the RFC number.]
[RFC EDITOR NOTE: Please replace RFCXXXX with the RFC number [RFC EDITOR NOTE: Please replace RFCXXXX with the RFC number
of this document.] of this document.]
Figure 1 Figure 1
16. Acknowledgments 16. Acknowledgments
The authors wish to thank Harald Alvestrand, Randell Jesup, Paul The authors wish to thank Harald Alvestrand, Randell Jesup, Paul
Kyzivat, Michael Tuexen, Juergen Stoetzer-Bradler, Flemming Andreasen Kyzivat, Michael Tuexen, Juergen Stoetzer-Bradler, Flemming Andreasen
and Ari Keranen for their comments and useful feedback. and Ari Keranen for their comments and useful feedback. Ben Campbell
provided comments as part of his AD review.
17. 17.
[RFC EDITOR NOTE: Please remove this section when publishing] [RFC EDITOR NOTE: Please remove this section when publishing]
Changes from draft-ietf-mmusic-sctp-sdp-21
o Changes based on AD review by Ben Campbell.
Changes from draft-ietf-mmusic-sctp-sdp-20 Changes from draft-ietf-mmusic-sctp-sdp-20
o Informative reference to draft-ietf-rtcweb-data-protocol added. o Informative reference to draft-ietf-rtcweb-data-protocol added.
Changes from draft-ietf-mmusic-sctp-sdp-19 Changes from draft-ietf-mmusic-sctp-sdp-19
o Changes based on WG chair comments from Flemming Andreasen. o Changes based on WG chair comments from Flemming Andreasen.
Changes from draft-ietf-mmusic-sctp-sdp-18 Changes from draft-ietf-mmusic-sctp-sdp-18
skipping to change at page 22, line 37 skipping to change at page 22, line 41
o - SDP Offer/Answer procedures. o - SDP Offer/Answer procedures.
o Text about SDP direction attributes added. o Text about SDP direction attributes added.
o Text about TLS role determination added. o Text about TLS role determination added.
18. References 18. References
18.1. Normative References 18.1. Normative References
[RFC0793] Postel, J., "Transmission Control Protocol", STD 7,
RFC 793, DOI 10.17487/RFC0793, September 1981,
<http://www.rfc-editor.org/info/rfc793>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>. <http://www.rfc-editor.org/info/rfc2119>.
[RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model [RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model
with Session Description Protocol (SDP)", RFC 3264, with Session Description Protocol (SDP)", RFC 3264,
DOI 10.17487/RFC3264, June 2002, DOI 10.17487/RFC3264, June 2002,
<http://www.rfc-editor.org/info/rfc3264>. <http://www.rfc-editor.org/info/rfc3264>.
skipping to change at page 23, line 14 skipping to change at page 23, line 24
[RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
Description Protocol", RFC 4566, DOI 10.17487/RFC4566, Description Protocol", RFC 4566, DOI 10.17487/RFC4566,
July 2006, <http://www.rfc-editor.org/info/rfc4566>. July 2006, <http://www.rfc-editor.org/info/rfc4566>.
[RFC4571] Lazzaro, J., "Framing Real-time Transport Protocol (RTP) [RFC4571] Lazzaro, J., "Framing Real-time Transport Protocol (RTP)
and RTP Control Protocol (RTCP) Packets over Connection- and RTP Control Protocol (RTCP) Packets over Connection-
Oriented Transport", RFC 4571, DOI 10.17487/RFC4571, July Oriented Transport", RFC 4571, DOI 10.17487/RFC4571, July
2006, <http://www.rfc-editor.org/info/rfc4571>. 2006, <http://www.rfc-editor.org/info/rfc4571>.
[RFC4572] Lennox, J., "Connection-Oriented Media Transport over the
Transport Layer Security (TLS) Protocol in the Session
Description Protocol (SDP)", RFC 4572,
DOI 10.17487/RFC4572, July 2006,
<http://www.rfc-editor.org/info/rfc4572>.
[RFC4960] Stewart, R., Ed., "Stream Control Transmission Protocol", [RFC4960] Stewart, R., Ed., "Stream Control Transmission Protocol",
RFC 4960, DOI 10.17487/RFC4960, September 2007, RFC 4960, DOI 10.17487/RFC4960, September 2007,
<http://www.rfc-editor.org/info/rfc4960>. <http://www.rfc-editor.org/info/rfc4960>.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226, IANA Considerations Section in RFCs", BCP 26, RFC 5226,
DOI 10.17487/RFC5226, May 2008, DOI 10.17487/RFC5226, May 2008,
<http://www.rfc-editor.org/info/rfc5226>. <http://www.rfc-editor.org/info/rfc5226>.
[RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer [RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer
Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347, Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347,
January 2012, <http://www.rfc-editor.org/info/rfc6347>. January 2012, <http://www.rfc-editor.org/info/rfc6347>.
[RFC6544] Rosenberg, J., Keranen, A., Lowekamp, B., and A. Roach,
"TCP Candidates with Interactive Connectivity
Establishment (ICE)", RFC 6544, DOI 10.17487/RFC6544,
March 2012, <http://www.rfc-editor.org/info/rfc6544>.
[I-D.ietf-mmusic-4572-update] [I-D.ietf-mmusic-4572-update]
Lennox, J. and C. Holmberg, "Connection-Oriented Media Lennox, J. and C. Holmberg, "Connection-Oriented Media
Transport over TLS in SDP", draft-ietf-mmusic- Transport over TLS in SDP", draft-ietf-mmusic-
4572-update-10 (work in progress), January 2017. 4572-update-11 (work in progress), January 2017.
[I-D.ietf-mmusic-dtls-sdp] [I-D.ietf-mmusic-dtls-sdp]
Holmberg, C. and R. Shpount, "Using the SDP Offer/Answer Holmberg, C. and R. Shpount, "Using the SDP Offer/Answer
Mechanism for DTLS", draft-ietf-mmusic-dtls-sdp-15 (work Mechanism for DTLS", draft-ietf-mmusic-dtls-sdp-16 (work
in progress), October 2016. in progress), January 2017.
[I-D.ietf-tsvwg-sctp-dtls-encaps] [I-D.ietf-tsvwg-sctp-dtls-encaps]
Tuexen, M., Stewart, R., Jesup, R., and S. Loreto, "DTLS Tuexen, M., Stewart, R., Jesup, R., and S. Loreto, "DTLS
Encapsulation of SCTP Packets", draft-ietf-tsvwg-sctp- Encapsulation of SCTP Packets", draft-ietf-tsvwg-sctp-
dtls-encaps-09 (work in progress), January 2015. dtls-encaps-09 (work in progress), January 2015.
[I-D.ietf-mmusic-sdp-mux-attributes] [I-D.ietf-mmusic-sdp-mux-attributes]
Nandakumar, S., "A Framework for SDP Attributes when Nandakumar, S., "A Framework for SDP Attributes when
Multiplexing", draft-ietf-mmusic-sdp-mux-attributes-16 Multiplexing", draft-ietf-mmusic-sdp-mux-attributes-16
(work in progress), December 2016. (work in progress), December 2016.
18.2. Informative References 18.2. Informative References
[RFC0793] Postel, J., "Transmission Control Protocol", STD 7,
RFC 793, DOI 10.17487/RFC0793, September 1981,
<http://www.rfc-editor.org/info/rfc793>.
[RFC5245] Rosenberg, J., "Interactive Connectivity Establishment [RFC5245] Rosenberg, J., "Interactive Connectivity Establishment
(ICE): A Protocol for Network Address Translator (NAT) (ICE): A Protocol for Network Address Translator (NAT)
Traversal for Offer/Answer Protocols", RFC 5245, Traversal for Offer/Answer Protocols", RFC 5245,
DOI 10.17487/RFC5245, April 2010, DOI 10.17487/RFC5245, April 2010,
<http://www.rfc-editor.org/info/rfc5245>. <http://www.rfc-editor.org/info/rfc5245>.
[RFC6544] Rosenberg, J., Keranen, A., Lowekamp, B., and A. Roach,
"TCP Candidates with Interactive Connectivity
Establishment (ICE)", RFC 6544, DOI 10.17487/RFC6544,
March 2012, <http://www.rfc-editor.org/info/rfc6544>.
[I-D.ietf-rtcweb-data-channel] [I-D.ietf-rtcweb-data-channel]
Jesup, R., Loreto, S., and M. Tuexen, "WebRTC Data Jesup, R., Loreto, S., and M. Tuexen, "WebRTC Data
Channels", draft-ietf-rtcweb-data-channel-13 (work in Channels", draft-ietf-rtcweb-data-channel-13 (work in
progress), January 2015. progress), January 2015.
[I-D.ietf-mmusic-data-channel-sdpneg] [I-D.ietf-mmusic-data-channel-sdpneg]
Drage, K., Makaraju, M., Stoetzer-Bradler, J., Ejzak, R., Drage, K., Makaraju, M., Stoetzer-Bradler, J., Ejzak, R.,
and (. (Unknown), "SDP-based Data Channel Negotiation", and (. (Unknown), "SDP-based Data Channel Negotiation",
draft-ietf-mmusic-data-channel-sdpneg-10 (work in draft-ietf-mmusic-data-channel-sdpneg-10 (work in
progress), September 2016. progress), September 2016.
 End of changes. 44 change blocks. 
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