draft-ietf-mmusic-sctp-sdp-26.txt   rfc8841.txt 
MMUSIC C. Holmberg Internet Engineering Task Force (IETF) C. Holmberg
Internet-Draft Ericsson Request for Comments: 8841 Ericsson
Intended status: Standards Track R. Shpount Category: Standards Track R. Shpount
Expires: October 22, 2017 TurboBridge ISSN: 2070-1721 TurboBridge
S. Loreto S. Loreto
G. Camarillo G. Camarillo
Ericsson Ericsson
April 20, 2017 January 2021
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-26
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. RFC
draft-ietf-tsvwg-sctp-dtls-encaps-09 specifies how SCTP can be used 8261 specifies how SCTP can be used on top of the Datagram Transport
on top of the Datagram Transport Layer Security (DTLS) protocol, Layer Security (DTLS) protocol, which is referred to as SCTP-over-
referred to as SCTP-over-DTLS. DTLS.
This specification defines the following new Session Description This specification defines the following new Session Description
Protocol (SDP) protocol identifiers (proto values):'UDP/DTLS/SCTP' Protocol (SDP) protocol identifiers (proto values): "UDP/DTLS/SCTP"
and 'TCP/DTLS/SCTP'. This specification also specifies how to use and "TCP/DTLS/SCTP". This specification also specifies how to use
the new proto values with the SDP Offer/Answer mechanism for the new proto values with the SDP offer/answer mechanism for
negotiating SCTP-over-DTLS associations. negotiating SCTP-over-DTLS associations.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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Internet-Drafts are draft documents valid for a maximum of six months This document is a product of the Internet Engineering Task Force
and may be updated, replaced, or obsoleted by other documents at any (IETF). It represents the consensus of the IETF community. It has
time. It is inappropriate to use Internet-Drafts as reference received public review and has been approved for publication by the
material or to cite them other than as "work in progress." Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
This Internet-Draft will expire on October 22, 2017. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8841.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Conventions
3. SCTP Terminology . . . . . . . . . . . . . . . . . . . . . . 4 3. SCTP Terminology
4. SDP Media Descriptions . . . . . . . . . . . . . . . . . . . 4 4. SDP Media Descriptions
4.1. General . . . . . . . . . . . . . . . . . . . . . . . . . 4 4.1. General
4.2. Protocol Identifiers . . . . . . . . . . . . . . . . . . 5 4.2. Protocol Identifiers
4.3. Media Format Management . . . . . . . . . . . . . . . . . 5 4.3. Media-Format Management
4.4. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . 5 4.4. Syntax
4.4.1. General . . . . . . . . . . . . . . . . . . . . . . . 6 4.4.1. General
4.4.2. SDP Media Description values . . . . . . . . . . . . 6 4.4.2. SDP Media Description Values
4.5. Example . . . . . . . . . . . . . . . . . . . . . . . . . 6 4.5. Example
5. SDP 'sctp-port' Attribute . . . . . . . . . . . . . . . . . . 6 5. SDP "sctp-port" Attribute
5.1. General . . . . . . . . . . . . . . . . . . . . . . . . . 6 5.1. General
5.2. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . 7 5.2. Syntax
5.3. Mux Category . . . . . . . . . . . . . . . . . . . . . . 7 5.3. Mux Category
6. SDP 'max-message-size' Attribute . . . . . . . . . . . . . . 8 6. SDP "max-message-size" Attribute
6.1. General . . . . . . . . . . . . . . . . . . . . . . . . . 8 6.1. General
6.2. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . 8 6.2. Syntax
6.3. Mux Category . . . . . . . . . . . . . . . . . . . . . . 9 6.3. Mux Category
7. UDP/DTLS/SCTP Transport Realization . . . . . . . . . . . . . 9 7. UDP/DTLS/SCTP Transport Realization
8. TCP/DTLS/SCTP Transport Realization . . . . . . . . . . . . . 10 8. TCP/DTLS/SCTP Transport Realization
9. Association And Connection Management . . . . . . . . . . . . 10 9. Association and Connection Management
9.1. General . . . . . . . . . . . . . . . . . . . . . . . . . 10 9.1. General
9.2. SDP sendrecv/sendonly/recvonly/inactive Attribute . . . . 10 9.2. SDP "sendrecv"/"sendonly"/"recvonly"/"inactive" Attributes
9.3. SCTP Association . . . . . . . . . . . . . . . . . . . . 10 9.3. SCTP Association
9.4. DTLS Association (UDP/DTLS/SCTP And TCP/DTLS/SCTP) . . . 11 9.4. DTLS Association (UDP/DTLS/SCTP and TCP/DTLS/SCTP)
9.5. TCP Connection (TCP/DTLS/SCTP) . . . . . . . . . . . . . 12 9.5. TCP Connection (TCP/DTLS/SCTP)
10. SDP Offer/Answer Procedures . . . . . . . . . . . . . . . . . 12 10. SDP Offer/Answer Procedures
10.1. General . . . . . . . . . . . . . . . . . . . . . . . . 12 10.1. General
10.2. Generating the Initial SDP Offer . . . . . . . . . . . . 13 10.2. Generating the Initial SDP Offer
10.3. Generating the SDP Answer . . . . . . . . . . . . . . . 13 10.3. Generating the SDP Answer
10.4. Offerer Processing of the SDP Answer . . . . . . . . . . 14 10.4. Offerer Processing of the SDP Answer
10.5. Modifying the Session . . . . . . . . . . . . . . . . . 15 10.5. Modifying the Session
11. Multihoming Considerations . . . . . . . . . . . . . . . . . 16 11. Multihoming Considerations
12. NAT Considerations . . . . . . . . . . . . . . . . . . . . . 16 12. NAT Considerations
12.1. General . . . . . . . . . . . . . . . . . . . . . . . . 16 12.1. General
12.2. ICE Considerations . . . . . . . . . . . . . . . . . . . 16 12.2. ICE Considerations
13. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 17 13. Examples
13.1. Establishment of UDP/DTLS/SCTP association . . . . . . . 17 13.1. Establishment of UDP/DTLS/SCTP Association
14. Security Considerations . . . . . . . . . . . . . . . . . . . 18 14. Security Considerations
15. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19 15. IANA Considerations
15.1. New SDP proto values . . . . . . . . . . . . . . . . . . 19 15.1. New SDP Proto Values
15.2. New SDP Attributes . . . . . . . . . . . . . . . . . . . 19 15.2. New SDP Attributes
15.2.1. sctp-port . . . . . . . . . . . . . . . . . . . . . 19 15.2.1. sctp-port
15.2.2. max-message-size . . . . . . . . . . . . . . . . . . 19 15.2.2. max-message-size
15.3. association-usage Name Registry . . . . . . . . . . . . 19 15.3. association-usage Name Registry
16. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 20 16. References
17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 16.1. Normative References
18. References . . . . . . . . . . . . . . . . . . . . . . . . . 23 16.2. Informative References
18.1. Normative References . . . . . . . . . . . . . . . . . . 23 Acknowledgements
18.2. Informative References . . . . . . . . . . . . . . . . . 25 Authors' Addresses
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 25
1. Introduction 1. Introduction
SDP (Session Description Protocol) [RFC4566] provides a general- The Session Description Protocol (SDP) [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
and establishing TCP [RFC0793] streams. Connection-Oriented Media describing and establishing TCP [RFC0793] streams. "Connection-
Transport over the Transport Layer Security (TLS) Protocol in SDP Oriented Media Transport over the Transport Layer Security (TLS)
[RFC8122] extends RFC4145 [RFC4145] for describing TCP-based media Protocol in the Session Description Protocol (SDP)" [RFC8122] extends
streams that are protected using TLS. [RFC4145] to describe 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
reliable transport protocol used to transport data between two reliable transport protocol used to transport data between two
endpoints using SCTP associations. endpoints using SCTP associations.
[I-D.ietf-tsvwg-sctp-dtls-encaps] specifies how SCTP can be used on [RFC8261] specifies how SCTP can be used on top of the Datagram
top of the Datagram Transport Layer Security (DTLS) protocol, Transport Layer Security (DTLS) protocol, an arrangement referred to
referred to as SCTP-over-DTLS. as SCTP-over-DTLS.
This specification defines the following new Session Description This specification defines the following new SDP [RFC4566] protocol
Protocol (SDP) [RFC4566] protocol identifiers (proto identifiers (proto values): "UDP/DTLS/SCTP" and "TCP/DTLS/SCTP".
values):'UDP/DTLS/SCTP' and 'TCP/DTLS/SCTP'. This specification also This document also specifies how to use the new proto values with the
specifies how to use the new proto values with the SDP Offer/Answer SDP offer/answer mechanism [RFC3264] for negotiating SCTP-over-DTLS
mechanism [RFC3264] for negotiating SCTP-over-DTLS associations. associations.
NOTE: Due to the characteristics of TCP, while multiple SCTP streams | NOTE: Due to the characteristics of TCP, while multiple SCTP
can still be used, usage of 'TCP/DTLS/SCTP' will always force ordered | streams can still be used, usage of "TCP/DTLS/SCTP" will always
and reliable delivery of the SCTP packets, which limits the usage of | force ordered and reliable delivery of the SCTP packets, which
the SCTP options. Therefore, it is RECOMMENDED that TCP is only used | limits the usage of the SCTP options. Therefore, it is
in situations where UDP traffic is blocked. | RECOMMENDED that TCP is only used in situations where UDP
| traffic is 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", "NOT RECOMMENDED", "MAY", and
document are to be interpreted as described in [RFC2119]. "OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
3. SCTP Terminology 3. SCTP Terminology
SCTP Association: A protocol relationship between SCTP endpoints, SCTP association: A protocol relationship between SCTP endpoints,
composed of the two SCTP endpoints and protocol state information composed of the two SCTP endpoints and protocol state information
including Verification Tags and the currently active set of including verification tags and the currently active set of
Transmission Sequence Numbers (TSNs), etc. An association can be Transmission Sequence Numbers (TSNs), etc. An association can be
uniquely identified by the transport addresses used by the endpoints uniquely identified by the transport addresses used by the
in the association. endpoints in the association.
SCTP Stream: A unidirectional logical channel established from one to SCTP stream: A unidirectional logical channel established from one
another associated SCTP endpoint, within which all user messages are associated SCTP endpoint to another, within which all user
delivered in sequence except for those submitted to the unordered messages are delivered in sequence except for those submitted to
delivery service. the unordered delivery service.
SCTP-over-DTLS: SCTP used on top of DTLS, as specified in SCTP-over-DTLS: SCTP used on top of DTLS, as specified in [RFC8261].
[I-D.ietf-tsvwg-sctp-dtls-encaps].
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]:
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
used, the underlying transport protocol is respectively UDP and TCP; | are used, the underlying transport protocol is, respectively,
SCTP is carried on top of DTLS which is on top of those transport- | UDP and TCP; SCTP is carried on top of DTLS, which is on top of
layer protocols. | those transport-layer protocols.
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 * 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 * 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] states 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 an "m=" line MUST further indicate the application-
protocol using an 'fmt' identifier. There MUST be exactly one fmt layer protocol using an "fmt" identifier. There MUST be exactly one
value per m- line associated with the proto values defined in this fmt value per "m=" line associated with the proto values defined in
specification. The 'fmt' namespace associated with those proto this 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.
When the 'UDP/DTLS/SCTP' and 'TCP/DTLS/SCTP' proto values, the m- When the "UDP/DTLS/SCTP" and "TCP/DTLS/SCTP" proto values are used,
line fmt value, identifying the application-layer protocol, MUST be the "m=" line fmt value, which identifies the application-layer
registered by IANA. Section 15.3 defines the IANA registry for the protocol, MUST be registered by IANA. Section 15.3 defines the IANA
media format namespace. registry for the media-format namespace.
NOTE: A mechanism on how to describe, and manage, individual SCTP | NOTE: A mechanism for how to describe and manage individual
streams within an SCTP association, is outside the scope of this | SCTP streams within an SCTP association is outside the scope of
specification. [I-D.ietf-mmusic-data-channel-sdpneg] defines a | this specification. [RFC8864] defines a mechanism for
mechanism for negotiating individual SCTP streams used to realize | negotiating individual SCTP streams used to realize WebRTC data
WebRTC data channels [I-D.ietf-rtcweb-data-channel]. | channels [RFC8831].
4.4. Syntax 4.4. Syntax
4.4.1. General 4.4.1. General
This section defines the values that can be used within an SDP media This section defines the values that can be used within an SDP media
description ("m=" line) associated with an SCTP-over-DTLS description ("m=" line) associated with an SCTP-over-DTLS
association. association.
This specification creates an IANA registry for 'association-usage' This specification creates an IANA registry for "association-usage"
values. values.
4.4.2. SDP Media Description values 4.4.2. SDP Media Description Values
m= line parameter parameter value(s) When the SCTP association is used to realize a WebRTC data channel
------------------------------------------------------------------ [RFC8832], the <fmt> parameter value is 'webrtc-datachannel'.
<media>: 'application'
<proto>: 'UDP/DTLS/SCTP' or 'TCP/DTLS/SCTP' +===========+===================================================+
<port>: UDP port number (for 'UDP/DTLS/SCTP') | "m=" line | parameter value(s) |
TCP port number (for 'TCP/DTLS/SCTP') | parameter | |
<fmt>: a string denoting the association-usage, +===========+===================================================+
limited to the syntax of a 'token' as | <media> | "application" |
defined in RFC4566. +-----------+---------------------------------------------------+
| <proto> | "UDP/DTLS/SCTP" or "TCP/DTLS/SCTP" |
+-----------+---------------------------------------------------+
| <port> | UDP port number (for "UDP/DTLS/SCTP") |
| | TCP port number (for "TCP/DTLS/SCTP") |
+-----------+---------------------------------------------------+
| <fmt> | A string denoting the association-usage, limited |
| | to the syntax of a "token" as defined in RFC 4566 |
+-----------+---------------------------------------------------+
Table 1: SDP Media Description Values
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=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 [RFC8832].
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".
The attribute can be associated with an SDP media description (m- The attribute can be associated with an SDP media description ("m="
line) with a 'UDP/DTLS/SCTP' or a 'TCP/DTLS/SCTP' proto value. In line) with a "UDP/DTLS/SCTP" or a "TCP/DTLS/SCTP" proto value. In
that case the m- line port value indicates the port of the underlying that case, the "m=" line port value indicates the port of the
transport layer protocol (UDP or TCP), and the 'sctp-port' value underlying transport-layer protocol (UDP or TCP), and the "sctp-port"
indicates the SCTP port. value indicates the SCTP port.
No default value is defined for the SDP sctp-port attribute. No default value is defined for the SDP "sctp-port" attribute.
Therefore, if the attribute is not present, the associated m- line Therefore, if the attribute is not present, the associated "m=" line
MUST be considered invalid. MUST be considered invalid.
NOTE: This specification only defines the usage of the SDP 'sctp- | NOTE: This specification only defines the usage of the SDP
port' attribute when associated with an m- line containing one of the | "sctp-port" attribute when associated with an "m=" line
following proto values: 'UDP/DTLS/SCTP' or 'TCP/DTLS/SCTP'. Usage of | containing one of the following proto values: "UDP/DTLS/SCTP"
the attribute with other proto values needs to be defined in a | or "TCP/DTLS/SCTP". Usage of the attribute with other proto
separate specification. | values needs to be defined in a separate specification.
5.2. Syntax 5.2. Syntax
[RFC EDITOR NOTE: Please replace RFCXXXX with the RFC number of this The definition of the SDP "sctp-port" attribute is:
document.]
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: CAUTION
Subject to charset: No
Purpose: Indicate the SCTP port value associated with
the SDP Media Description.
Appropriate values: Integer
Contact name: Christer Holmberg
Contact e-mail: christer.holmberg@ericsson.com
Reference: RFCXXXX
Syntax: Mux category: CAUTION
sctp-port-value = 1*5<DIGIT defined in RFC4566> Subject to charset: No
The SCTP port range is between 0 and 65535 (both included). Purpose: Indicate the SCTP port value associated with the SDP media
Leading zeroes MUST NOT be used. description.
Example: Appropriate values: Integer
a=sctp-port:5000 Contact name: Christer Holmberg
Contact e-mail: christer.holmberg@ericsson.com
Reference: RFC 8841
Syntax:
sctp-port-value = 1*5(DIGIT) ; DIGIT defined in RFC 4566
The SCTP port range is between 0 and 65535 (both included). Leading
zeroes MUST NOT be used.
Example:
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 [RFC8859] for the SDP "sctp-port" attribute is
'sctp-port' attribute is CAUTION. 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 NOT send a SCTP user message with a message An SCTP endpoint MUST NOT send a SCTP user message with a message
size that is larger than the maximum size indicated by the peer, as size that is larger than the maximum size indicated by the peer, as
it cannot be assumed that the peer would accept such message. it cannot be assumed that the peer would accept such a message.
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 that 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
message-size' attribute when associated with an m- line containing | "max-message-size" attribute when associated with an "m=" line
one of the following proto values: 'UDP/DTLS/SCTP' or 'TCP/DTLS/ | containing one of the following proto values: "UDP/DTLS/SCTP"
SCTP'. Usage of the attribute with other proto values needs to be | or "TCP/DTLS/SCTP". Usage of the attribute with other proto
defined in a separate specification. | values needs to be defined in a separate specification.
6.2. Syntax 6.2. Syntax
[RFC EDITOR NOTE: Please replace RFCXXXX with the RFC number of this The definition of the SDP "max-message-size" attribute is:
document.]
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: CAUTION
Subject to charset: No
Purpose: Indicate the maximum message size
(indicated in bytes) that an SCTP
endpoint is willing to receive on the
SCTP association associated with the SDP
Media Description.
Appropriate values: Integer
Contact name: Christer Holmberg
Contact e-mail: christer.holmberg@ericsson.com
Reference: RFCXXXX
Syntax: Mux category: CAUTION
max-message-size-value = 1*<DIGIT defined in RFC4566> Subject to charset: No
Leading zeroes MUST NOT be used. Purpose: Indicate the maximum message size (indicated in bytes) that
an SCTP endpoint is willing to receive on the SCTP association
associated with the SDP media description.
Example: Appropriate values: Integer
a=max-message-size:100000 Contact name: Christer Holmberg
Contact e-mail: christer.holmberg@ericsson.com
Reference: RFC 8841
Syntax:
max-message-size-value = 1*DIGIT ; DIGIT defined in RFC 4566
Leading zeroes MUST NOT be used.
Example:
a=max-message-size:100000
6.3. Mux Category 6.3. Mux Category
The mux category for the SDP 'max-message-size' attribute is CAUTION. 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:
o SCTP on top of DTLS is realized according to the procedures * SCTP on top of DTLS is realized according to the procedures
defined in [I-D.ietf-tsvwg-sctp-dtls-encaps]; and defined in [RFC8261]; and
o DTLS on top of UDP is realized according to the procedures in * DTLS on top of UDP is realized according to the procedures in
defined in [RFC6347]. defined in [RFC6347].
NOTE: While [I-D.ietf-tsvwg-sctp-dtls-encaps] allows multiple SCTP | NOTE: While [RFC8261] allows multiple SCTP associations on top
associations on top of a single DTLS association, the procedures in | of a single DTLS association, the procedures in this
this specification only support the negotiation of a single SCTP | specification only support the negotiation of a single SCTP
association on top of any given DTLS association. | association on top of any given DTLS association.
8. TCP/DTLS/SCTP Transport Realization 8. TCP/DTLS/SCTP Transport Realization
The TCP/DTLS/SCTP transport is realized as described below: The TCP/DTLS/SCTP transport is realized as described below:
o SCTP on top of DTLS is realized according to the procedures * SCTP on top of DTLS is realized according to the procedures
defined in [I-D.ietf-tsvwg-sctp-dtls-encaps]; and defined in [RFC8261]; and
o DTLS on top of TCP is realized using the framing method defined in * DTLS on top of TCP is realized using the framing method defined in
[RFC4571], with DTLS packets being sent and received instead of [RFC4571], with DTLS packets being sent and received instead of
RTP/RTCP packets using the shim defined in [RFC4571], so that RTP/RTCP packets using the shim defined in [RFC4571]. The length
length field defined in [RFC4571] precedes each DTLS message, and field defined in [RFC4571] precedes each DTLS message, and SDP
SDP signaling according to the procedures defined in this signaling is done according to the procedures defined in this
specification. specification.
NOTE: TLS on top of TCP, without using the framing method defined in | NOTE: TLS on top of TCP, without using the framing method
[RFC4571] is outside the scope of this specification. A separate | defined in [RFC4571], is outside the scope of this
proto value would need to be registered for such transport | specification. A separate proto value would need to be
realization. | registered for such transport realization.
9. Association And Connection Management 9. Association and Connection Management
9.1. General 9.1. General
This section describes how to manage 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
managed independently from each other. Each can be established and are managed independently from each other. Each can be established
closed without impacting others. and 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" Attributes
This specification does not define semantics for the SDP direction This specification does not define semantics for the SDP direction
attributes [RFC4566]. Unless semantics of these attributes for an attributes [RFC4566]. Unless the semantics of these attributes for
SCTP association usage have been defined, SDP direction attributes an SCTP association usage have been defined, SDP direction attributes
MUST be ignored if present. MUST be ignored if present.
9.3. SCTP Association 9.3. SCTP Association
When an SCTP association is established, both SCTP endpoints MUST When an SCTP association is established, both SCTP endpoints MUST
initiate the SCTP association (i.e. both SCTP endpoints take the initiate the SCTP association (i.e., both SCTP endpoints take the
'active' role), and MUST use the same SCTP port as client port and "active" role). In addition, both endpoints MUST use the same SCTP
server port (in order to prevent two separate SCTP associations from port as client port and server port, in order to prevent two separate
being established). SCTP associations from being established.
As both SCTP endpoints take the 'active' role, the SDP 'setup' As both SCTP endpoints take the "active" role, the SDP "setup"
attribute [RFC4145] does not apply to SCTP association establishment. attribute [RFC4145] does not apply to SCTP association establishment.
However the 'setup' attribute does apply to establishment of the However, the "setup" attribute does apply to establishment of the
underlying DTLS association and TCP connection. underlying DTLS association and TCP connection.
NOTE: The procedure above is different from TCP, where one endpoint | NOTE: The procedure above is different from TCP, where one
takes the 'active' role, the other endpoint takes the 'passive' role, | endpoint takes the "active" role, the other endpoint takes the
and only the 'active' endpoint initiates the TCP connection | "passive" role, and only the "active" endpoint initiates the
[RFC4145]. | TCP connection [RFC4145].
NOTE: When the SCTP association is established it is assumed that any | NOTE: When the SCTP association is established, it is assumed
NAT traversal procedures for the underlying transport protocol (UDP | that any NAT traversal procedures for the underlying transport
or TCP) have successfully been performed. | protocol (UDP or TCP) have successfully been performed.
The SDP 'connection' attribute [RFC4145] does not apply to the SCTP The SDP "connection" attribute [RFC4145] does not apply to the SCTP
association. In order to trigger the closure of an existing SCTP association. In order to trigger the closure of an existing SCTP
association, and establishment of a new SCTP association, the SDP association and establishment of a new SCTP association, the SDP
'sctp-port' attribute [Section 5] is used to indicate a new "sctp-port" attribute (Section 5) is used to indicate a new
(different than the ones currently used) SCTP port. The existing (different than the ones currently used) SCTP port. The existing
SCTP association is closed, and the new SCTP association is SCTP association is closed, and the new SCTP association is
established, if one or both endpoints signal a new SCTP port. The established, if one or both endpoints signal a new SCTP port. The
'connection' attribute does apply to establishment of underlying TCP "connection" attribute does apply to establishment of underlying TCP
connections. connections.
Alternatively, an SCTP association can be closed using the SDP 'sctp- Alternatively, an SCTP association can be closed using the SDP "sctp-
port' attribute with a zero attribute value. Later, a new SCTP port" attribute with an attribute value of zero. Later, a new SCTP
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 signaling -- for
case of a failure. The procedures in this section MUST be followed example, in case of a failure. The procedures in this section MUST
to establish a new SCTP association. This requires a new SDP Offer/ be followed to establish a new SCTP association. This requires a new
Answer exchange. New (different than the ones currently used) SCTP SDP offer/answer exchange. New (different than the ones currently
ports MUST be used by both endpoints. used) SCTP 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
'sctp-port' attribute will not affect the state of the underlying | SDP "sctp-port" attribute will not affect the state of the
DTLS association. | underlying 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 [RFC8842]. Hence, the SDP "setup" attribute is used to negotiate the
to negotiate the (D)TLS roles ('client' and 'server') [RFC8122]. (D)TLS roles ("client" and "server") [RFC8122].
NOTE: The SDP 'setup' attribute is used to negotiate both the DTLS | NOTE: The SDP "setup" attribute is used to negotiate both the
roles and the TCP roles (Section 9.5). | DTLS roles and the TCP roles (Section 9.5).
NOTE: As described in [RFC5245], if the Interactive Connectivity | NOTE: As described in [RFC8445], if the Interactive
Establishment (ICE) mechanism [RFC5245] is used, all ICE candidates | Connectivity Establishment (ICE) mechanism [RFC8445] is used,
associated with a DTLS association are considered part of the same | all ICE candidates associated with a DTLS association are
DTLS association. Thus, a switch from one candidate pair to another | considered part of the same DTLS association. Thus, a switch
candidate pair will not trigger the establishment of a new DTLS | from one candidate pair to another candidate pair will not
association. | trigger the establishment of a new DTLS association.
9.5. TCP Connection (TCP/DTLS/SCTP) 9.5. TCP Connection (TCP/DTLS/SCTP)
The TCP connection is managed according to the procedures in The TCP connection is managed according to the procedures in
[RFC4145]. Hence, the SDP 'setup' attribute is used to negotiate the [RFC4145]. Hence, the SDP "setup" attribute is used to negotiate the
TCP roles ('active' and 'passive'), and the SDP 'connection' TCP roles ("active" and "passive"), and the SDP "connection"
attribute is used to indicate whether to use an existing TCP attribute is used to indicate whether to use an existing TCP
connection, or create a new one. The SDP 'setup' attribute connection or create a new one. The SDP "setup" attribute "holdconn"
'holdconn' value MUST NOT be used. value MUST NOT be used.
NOTE: A change of the TCP roles will also trigger a closure of the | NOTE: A change of the TCP roles will also trigger a closure of
DTLS association, and establishment of a new DTLS association, | the DTLS association and establishment of a new DTLS
according to the procedures in [I-D.ietf-mmusic-dtls-sdp]. | association, according to the procedures in [RFC8842].
NOTE: As specified in [I-D.ietf-mmusic-dtls-sdp], usage of the SDP | NOTE: As specified in [RFC8842], usage of the SDP "setup"
'setup' attribute 'holdconn' value is not allowed. Therefore this | attribute "holdconn" value is not allowed. Therefore, this
specification also forbids usage of the attribute value for TCP, as | specification also forbids usage of the attribute value for
DTLS is transported on top of TCP. | TCP, as DTLS is transported on top of TCP.
10. SDP Offer/Answer Procedures 10. SDP Offer/Answer Procedures
10.1. General 10.1. General
This section defines the SDP Offer/Answer [RFC3264] procedures for This section defines the SDP Offer/Answer [RFC3264] procedures for
negotiating and establishing an SCTP-over-DTLS association. Unless negotiating and establishing an SCTP-over-DTLS association. Unless
explicitly stated, the procedures apply to both the 'UDP/DTLS/SCTP' explicitly stated, the procedures apply to both the "UDP/DTLS/SCTP"
and 'TCP/DTLS/SCTP' m- line proto values. and "TCP/DTLS/SCTP" "m=" line proto values.
Each endpoint MUST associate one or more certificate fingerprints, Each endpoint MUST associate one or more certificate fingerprints
using the SDP 'fingerprint' attribute with the m- line, following the using the SDP "fingerprint" attribute with the "m=" line, following
procedures in [RFC8122]. the procedures in [RFC8122].
The authentication certificates are interpreted and validated as The authentication certificates are interpreted and validated as
defined in [RFC8122]. Self-signed certificates can be used securely, defined in [RFC8122]. Self-signed certificates can be used securely,
provided that the integrity of the SDP description is assured as provided that the integrity of the SDP description is assured, as
defined in [RFC8122]. defined in [RFC8122].
Each endpoint MUST associate an SDP 'tls-id' attribute with the m- Each endpoint MUST associate an SDP "tls-id" attribute with the "m="
line, following the procedures in [I-D.ietf-mmusic-dtls-sdp]. line, following the procedures in [RFC8842].
10.2. Generating the Initial SDP Offer 10.2. Generating the Initial SDP Offer
When the offerer creates an initial offer, the offerer: When the offerer creates an initial offer, the offerer:
o MUST associate an SDP setup attribute with the m- line; * MUST associate an SDP "setup" attribute with the "m=" line;
o MUST associate an SDP 'sctp-port' attribute with the m- line; * MUST associate an SDP "sctp-port" attribute with the "m=" line;
o MUST, in the case of TCP/DTLS/SCTP, associate an SDP 'connection' * MUST, in the case of TCP/DTLS/SCTP, associate an SDP "connection"
attribute, with a 'new' attribute value, with the m- line; and attribute, with a "new" attribute value, with the "m=" line; and
o MAY associate an SDP 'max-message-size' attribute [Section 6] with * 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 that 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 m- line * MUST insert a corresponding "m=" line in the answer, with an "m="
proto value [RFC3264] identical to the value in the offer; line proto value [RFC3264] identical to the value in the offer;
o MUST associate an SDP 'setup' attribute with the m- line; * MUST associate an SDP "setup" attribute with the "m=" line;
o MUST associate an SDP 'sctp-port' attribute with the m- line. If * MUST associate an SDP "sctp-port" attribute with the "m=" line.
the offer contained a new (different than the one currently used) If the offer contained a new (different than the one currently
SCTP port value the answerer MUST also associate a new SCTP port used) SCTP port value, the answerer MUST also associate a new SCTP
value. If the offer contained a zero SCTP port value, or if the port value. If the offer contained a zero SCTP port value, or if
answerer does not accept the SCTP association, the answerer MUST the answerer does not accept the SCTP association, the answerer
also associate a zero SCTP port value; and MUST also associate a zero SCTP port value; and
o MAY associate an SDP 'max-message-size' attribute [Section 6] with * MAY associate an SDP "max-message-size" attribute (Section 6) with
the m- line. The attribute value in the answer is independent the "m=" line. The attribute value in the answer is independent
from the value (if present) in the corresponding m- line of the of the value (if present) in the corresponding "m=" line of the
offer. offer.
Once the answerer has sent the answer the answerer: Once the answerer has sent the answer:
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
closed and replaced by a new TCP connection, follow the procedures
in [RFC4145] for closing and establishing a TCP connection;
o MUST, if a DTLS association has not yet been established, or if an * in the case of TCP/DTLS/SCTP, if a TCP connection has not yet been
existing DTLS association is to be closed and replaced by a new established or an existing TCP connection is to be closed and
DTLS association, follow the procedures in replaced by a new one, the answerer MUST follow the procedures in
[RFC4145] for closing and establishing a TCP connection;
[I-D.ietf-mmusic-dtls-sdp] for closing the currently used, and * if a DTLS association has not yet been established or an existing
establishing a new, DTLS association; and DTLS association is to be closed and replaced by a new one, the
answerer MUST follow the procedures in [RFC8842] for closing the
currently used DTLS association and establishing a new one; and
o MUST, if an SCTP association has not yet been established, or if * if an SCTP association has not yet been established or an existing
an existing SCTP association is to be closed and replaced by a new SCTP association is to be closed and replaced by a new one, the
SCTP association, initiate the closing of the existing SCTP answerer MUST initiate the closing of the existing SCTP
association (if applicable) and establishment of the SCTP association (if applicable) and establishment of the new
association. association.
If the SDP 'sctp-port' attribute in the answer contains a zero If the SDP "sctp-port" attribute in the answer contains an attribute
attribute value, the answerer MUST NOT establish an SCTP association. value of zero, 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.
If the answerer does not accept the m- line in the offer, it MUST If the answerer does not accept the "m=" line in the offer, it MUST
assign a zero port value to the corresponding m- line in the answer, assign a zero port value to the corresponding "m=" line in the
following the procedures in [RFC3264]. In addition, the answerer answer, following the procedures in [RFC3264]. In addition, the
MUST NOT initiate the establishment of a TCP connection, a DTLS answerer MUST NOT initiate the establishment of a TCP connection, a
association or a DTLS association associated with the m- line. DTLS association, or a DTLS association associated with the "m="
line.
10.4. Offerer Processing of the SDP Answer 10.4. Offerer Processing of the SDP Answer
Once the offerer has received the answer the offerer: Once the offerer has received the answer:
o MUST, in the case of TCP/DTLS/SCTP, if a TCP connection has not * in the case of TCP/DTLS/SCTP, if a TCP connection has not yet been
yet been established, or if an existing TCP connection is to be established or an existing TCP connection is to be closed and
closed and replaced by a new TCP connection, follow the procedures replaced by a new one, the offerer MUST follow the procedures in
in [RFC4145] for closing and establishing a TCP connection; [RFC4145] for closing and establishing a TCP connection;
o MUST, if a DTLS association has not yet been established, or if an * if a DTLS association has not yet been established or an existing
existing DTLS association is to be closed and replaced by a new DTLS association is to be closed and replaced by a new one, the
DTLS association, follow the procedures in offerer MUST follow the procedures in [RFC8842] for closing and
[I-D.ietf-mmusic-dtls-sdp] for closing and establishing a DTLS establishing a DTLS association; and
association; and
o MUST, if an SCTP association has not yet been established, or if * if an SCTP association has not yet been established or an existing
an existing SCTP association is to be closed and replaced by a new SCTP association is to be closed and replaced by a new one, the
SCTP association, initiate the closing of the existing SCTP offerer MUST initiate the closing of the existing SCTP association
association (if applicable) and establishment of the SCTP (if applicable) and establishment of the new association.
association.
If the SDP 'sctp-port' attribute in the answer contains a zero If the SDP "sctp-port" attribute in the answer contains an attribute
attribute value, the offerer MUST NOT establish an SCTP association. value of zero, the offerer MUST NOT establish an SCTP association.
If an SCTP association exists in that case, the offerer MUST close If, in addition, an SCTP association exists, the offerer MUST close
it. it.
If the m- line in the answer contains a zero port value, the offerer If the "m=" line in the answer contains a zero port value, the
MUST NOT initiate the establishment a TCP connection, a DTLS offerer MUST NOT initiate the establishment of a TCP connection, a
association or an SCTP association associated with the m- line. If a DTLS association, or an SCTP association associated with the "m="
TCP connection, or a DTLS association or an SCTP association exists line. If, in addition, a TCP connection, DTLS association, or SCTP
in that case, the offerer MUST close it. association exists, the offerer MUST close it.
10.5. Modifying the Session 10.5. Modifying the Session
When an offerer sends an updated offer, in order to modify a When an offerer sends an updated offer, in order to modify a
previously established SCTP association, it follows the procedures in previously established SCTP association, it follows the procedures in
Section 10.2, with the following exceptions: Section 10.2, with the following exceptions:
o If the offerer wants to close an SCTP association, and immediately * If the offerer wants to close an SCTP association and immediately
establish a new SCTP association, the offerer MUST associate an establish a new SCTP association, it MUST associate an SDP "sctp-
SDP 'sctp-port' attribute with a new (different than the one port" attribute with a new (different than the one currently used)
currently used) attribute value. This will not impact the attribute value. This will not impact the underlying DTLS
underlying DTLS association (and TCP connection in case of association (or TCP connection, in the case of TCP/DTLS/SCTP).
TCP/DTLS/SCTP).
o If the offerer wants to close an SCTP association, without * If the offerer wants to close an SCTP association without
immediately establishing a new SCTP association, the offerer MUST immediately establishing a new SCTP association, it MUST associate
associate an SDP 'sctp-port' attribute with a zero attribute an SDP "sctp-port" attribute with an attribute value of zero.
value. This will not impact the underlying DTLS association (and This will not impact the underlying DTLS association (or TCP
TCP connection in case of TCP/DTLS/SCTP). connection, in the case of TCP/DTLS/SCTP).
o If the offerer wants to establish an SCTP association, and another * If the offerer wants to establish an SCTP association, and another
SCTP association was previously closed, the offerer MUST associate SCTP association was previously closed, the offerer MUST associate
an SDP 'sctp-port' attribute with a new attribute value (different an SDP "sctp-port" attribute with a new attribute value (different
than the value associated with the previous SCTP association). If than the value associated with the previous SCTP association). If
the previous SCTP association was closed successfully following the previous SCTP association was closed successfully following
use of an SDP 'sctp-port' attribute with a zero attribute value, use of an SDP "sctp-port" attribute with an attribute value of
the offerer MAY use the same attribute value for the new SCTP zero, the offerer MAY use the same attribute value for the new
association that was used with the previous SCTP association SCTP association that was used with the previous SCTP association
before it was closed. This will not impact the underlying DTLS before it was closed. This will not impact the underlying DTLS
association (and TCP connection in case of TCP/DTLS/SCTP). association (or TCP connection, in the case of TCP/DTLS/SCTP).
o If the offerer wants to close an existing SCTP association, and * If the offerer wants to close an existing SCTP association and the
the underlying DTLS association (and the underlying TCP connection underlying DTLS association (and the underlying TCP connection, in
in case of TCP/DTLS/SCTP) it MUST assign a zero port value to the the case of TCP/DTLS/SCTP), it MUST assign a zero port value to
m- line associated with the SCTP and DTLS associations (and TCP the "m=" line associated with the SCTP and DTLS associations (and
connection in case of TCP/DTLS/SCTP), following the procedures in TCP connection, in the case of TCP/DTLS/SCTP), following the
[RFC3264]. procedures in [RFC3264].
o NOTE: This specification does not define a mechanism for * 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 state of the some other action [RFC8842], the state of the SCTP association is
SCTP association is not affected. not affected.
The offer follows the procedures in [I-D.ietf-mmusic-dtls-sdp] The offerer follows the procedures in [RFC8842] regarding the DTLS
regarding the DTLS association impacts when modifying a session. 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
Multihoming is not supported when sending SCTP on top of DTLS, as Multihoming is not supported when sending SCTP on top of DTLS, as
DTLS does not expose address management of the underlying transport DTLS does not expose address management of the underlying transport
protocols (UDP or TCP) to its upper layer. protocols (UDP or TCP) to its upper layer.
12. NAT Considerations 12. NAT Considerations
12.1. General 12.1. General
When SCTP-over-DTLS is used in NAT environment, it relies on the NAT When SCTP-over-DTLS is used in a NAT environment, it relies on the
traversal procedures for the underlying transport protocol (UDP or NAT traversal procedures for the underlying transport protocol (UDP
TCP). or TCP).
12.2. ICE Considerations 12.2. ICE Considerations
When SCTP-over-DTLS is used with UDP based ICE candidates [RFC5245] When SCTP-over-DTLS is used with UDP-based ICE candidates [RFC8445],
then the procedures for UDP/DTLS/SCTP [Section 7] are used. then the procedures for UDP/DTLS/SCTP (Section 7) are used.
When SCTP-over-DTLS is used with TCP based ICE candidates [RFC6544] When SCTP-over-DTLS is used with TCP-based ICE candidates [RFC6544],
then the procedures for TCP/DTLS/SCTP [Section 8] are used. then the procedures for TCP/DTLS/SCTP (Section 8) are used.
In ICE environments, during the nomination process, endpoints go In ICE environments, during the nomination process, endpoints go
through multiple ICE candidate pairs, until the most preferred through multiple ICE candidate pairs until the most preferred
candidate pair is found. During the nomination process, data can be candidate pair is found. During the nomination process, data can be
sent as soon as the first working candidate pair is found, but the sent as soon as the first working candidate pair is found, but the
nomination process still continues and selected candidate pairs can nomination process still continues, and selected candidate pairs can
still change while data is sent. Furthermore, if endpoints roam still change while data is sent. Furthermore, if endpoints roam
between networks, for instance when mobile endpoint switches from between networks -- for instance, when a mobile endpoint switches
mobile connection to WiFi, endpoints will initiate an ICE restart, from mobile connection to WiFi -- endpoints will initiate an ICE
which will trigger a new nomination process between the new set of restart. This will trigger a new nomination process between the new
candidates and likely result in the new nominated candidate pair. set of candidates, which will likely result in the new nominated
candidate pair.
Implementations MUST treat all ICE candidate pairs associated with an Implementations MUST treat all ICE candidate pairs associated with an
SCTP association on top of a DTLS association as part of the same SCTP association on top of a DTLS association as part of the same
DTLS association. Thus, there will only be one SCTP handshake and DTLS association. Thus, there will only be one SCTP handshake and
one DTLS handshake even if there are multiple valid candidate pairs, one DTLS handshake even if there are multiple valid candidate pairs;
and shifting from one candidate pair to another, including switching shifting from one candidate pair to another, including switching
between UDP to TCP candidate pairs, will not impact the SCTP or DTLS between UDP and TCP candidate pairs, will not impact the SCTP or DTLS
associations. If new candidates are added, they will also be part of associations. If new candidates are added, they will also be part of
the same SCTP and DTLS associations. When transitioning between the same SCTP and DTLS associations. When transitioning between
candidate pairs, different candidate pairs can be currently active in candidate pairs, different candidate pairs can be currently active in
different directions and implementations MUST be ready to receive different directions, and implementations MUST be ready to receive
data on any of the candidates, even if this means sending and data on any of the candidates, even if this means sending and
receiving data using UDP/DTLS/SCTP and TCP/DTLS/SCTP at the same time receiving data using UDP/DTLS/SCTP and TCP/DTLS/SCTP at the same time
in different directions. in different directions.
In order to maximize the likelihood of interoperability between the In order to maximize the likelihood of interoperability between the
endpoints, all ICE enabled SCTP-over-DTLS endpoints SHOULD implement endpoints, all ICE-enabled SCTP-over-DTLS endpoints SHOULD implement
support for UDP/DTLS/SCTP. support for UDP/DTLS/SCTP.
When an SDP offer or answer is sent with multiple ICE candidates When an SDP offer or answer is sent with multiple ICE candidates
during initial connection negotiation or after ICE restart, UDP based during initial connection negotiation or after ICE restart, UDP-based
candidates SHOULD be included and default candidate SHOULD be chosen candidates SHOULD be included, and the default candidate SHOULD be
from one of those UDP candidates. The proto value MUST match the chosen from one of those UDP candidates. The proto value MUST match
transport protocol associated with the default candidate. If UDP the transport protocol associated with the default candidate. If UDP
transport is used for the default candidate, then 'UDP/DTLS/SCTP' transport is used for the default candidate, then the "UDP/DTLS/SCTP"
proto value MUST be used. If TCP transport is used for the default proto value MUST be used. If TCP transport is used for the default
candidate, then 'TCP/DTLS/SCTP' proto value MUST be used. Note that candidate, then the "TCP/DTLS/SCTP" proto value MUST be used. Note
under normal circumstances the proto value for offers and answers that under normal circumstances, the proto value for offers and
sent during ICE nomination SHOULD be 'UDP/DTLS/SCTP'. answers sent during ICE nomination SHOULD be "UDP/DTLS/SCTP".
When a subsequent SDP offer or answer is sent after ICE nomination is When a subsequent SDP offer or answer is sent after ICE nomination is
complete, and does not initiate ICE restart, it will contain only the complete, and it does not initiate ICE restart, it will contain only
nominated ICE candidate pair. In this case, the proto value MUST the nominated ICE candidate pair. In this case, the proto value MUST
match the transport protocol associated with the nominated ICE match the transport protocol associated with the nominated ICE
candidate pair. If UDP transport is used for the nominated pair, candidate pair. If UDP transport is used for the nominated pair,
then 'UDP/DTLS/SCTP' proto value MUST be used. If TCP transport is then the "UDP/DTLS/SCTP" proto value MUST be used. If TCP transport
used for the nominated pair, then 'TCP/DTLS/SCTP' proto value MUST be is used for the nominated pair, then the "TCP/DTLS/SCTP" proto value
used. Please note that if an endpoint switches between TCP-based and MUST be used. Please note that if an endpoint switches between TCP-
UDP-based candidates during the nomination process the endpoint is based and UDP-based candidates during the nomination process, the
not required to send an SDP offer for the sole purpose of keeping the endpoint is not required to send an SDP offer for the sole purpose of
proto value of the associated m- line in sync. keeping the proto value of the associated "m=" line in sync.
NOTE: The text in the paragraph above only applies when the usage of | NOTE: The text in the paragraph above only applies when the
ICE has been negotiated. If ICE is not used, the proto value MUST | usage of ICE has been negotiated. If ICE is not used, the
always reflect the transport protocol used at any given time. | proto value MUST always reflect the transport protocol used at
| any given time.
13. Examples 13. Examples
13.1. Establishment of UDP/DTLS/SCTP association 13.1. Establishment of UDP/DTLS/SCTP Association
SDP Offer:
m=application 54111 UDP/DTLS/SCTP webrtc-datachannel SDP Offer:
c=IN IP6 2001:DB8::A8FD
a=tls-id:abc3de65cddef001be82
a=setup:actpass
a=sctp-port:5000
a=max-message-size:100000
- The offerer indicates that the usage of the m=application 54111 UDP/DTLS/SCTP webrtc-datachannel
UDP/DTLS/SCTP association will be as defined c=IN IP6 2001:DB8::A8FD
for the 'webrtc-datachannel' format value. a=tls-id:abc3de65cddef001be82
- The offerer UDP port value is 54111. a=setup:actpass
- The offerer SCTP port value is 5000. a=fingerprint:SHA-256 \
- The offerer indicates that it can take either the 12:DF:3E:5D:49:6B:19:E5:7C:AB:4A:AD:B9:B1:3F:82:18:3B:54:02:12:DF: \
client or the server DTLS role. 3E:5D:49:6B:19:E5:7C:AB:4A:AD
a=sctp-port:5000
a=max-message-size:100000
SDP Answer: * The offerer indicates that the usage of the UDP/DTLS/SCTP
association will be as defined for the "webrtc-datachannel" format
value.
m=application 64300 UDP/DTLS/SCTP webrtc-datachannel * The offerer UDP port value is 54111.
c=IN IP6 2001:DB8::001D
a=tls-id:dbc8de77cddef001be90
a=setup:passive
a=sctp-port:6000
a=max-message-size:100000
- The answerer UDP port value is 64300. * The offerer SCTP port value is 5000.
- The answerer SCTP port value is 6000.
- The answerer takes the server DTLS role. * The offerer indicates that it can take either the client or the
server DTLS role.
SDP Answer:
m=application 64300 UDP/DTLS/SCTP webrtc-datachannel
c=IN IP6 2001:DB8::001D
a=tls-id:dbc8de77cddef001be90
a=setup:passive
a=fingerprint:SHA-256 \
3F:82:18:3B:49:6B:19:E5:7C:AB:4A:AD:B9:B1:12:DF:3E:5D:12:DF:54:02: \
49:6B:3E:5D:7C:AB:19:E5:AD:4A
a=sctp-port:6000
a=max-message-size:100000
Note that due to RFC formatting conventions, this document splits SDP
across lines whose content would exceed 72 characters. A backslash
character marks where this line folding has taken place. This
backslash and its trailing CRLF and whitespace would not appear in
actual SDP content.
* The answerer UDP port value is 64300.
* The answerer SCTP port value is 6000.
* 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 [RFC8122] define security considerations [RFC3264], [RFC4145], and [RFC8122] define security considerations
when using the SDP offer/answer mechanism to negotiate media streams. 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 [RFC8261]
[I-D.ietf-tsvwg-sctp-dtls-encaps] defines security considerations 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
15.1. New SDP proto values 15.1. New SDP Proto Values
[RFC EDITOR NOTE: Please replace RFCXXXX with the RFC number of this
document.]
This document updates the "Session Description Protocol (SDP) This document updates the "Session Description Protocol (SDP)
Parameters" registry, following the procedures in [RFC4566], by Parameters" registry, following the procedures in [RFC4566], by
adding the following values to the table in the SDP "proto" field adding the following values to the table in the SDP "proto" field
registry: registry:
+-------+---------------+-----------+ +=======+===============+===========+
| Type | SDP Name | Reference | | Type | SDP Name | Reference |
+=======+===============+===========+
| proto | UDP/DTLS/SCTP | RFC 8841 |
+-------+---------------+-----------+ +-------+---------------+-----------+
| proto | UDP/DTLS/SCTP | [RFCXXXX] | | proto | TCP/DTLS/SCTP | RFC 8841 |
| proto | TCP/DTLS/SCTP | [RFCXXXX] |
+-------+---------------+-----------+ +-------+---------------+-----------+
Table 1: SDP "proto" field values Table 2: SDP "proto" Field Values
15.2. New SDP Attributes 15.2. New SDP Attributes
15.2.1. sctp-port 15.2.1. sctp-port
This document defines a new SDP media-level attribute,'sctp-port'. This document defines a new SDP media-level attribute,"sctp-port".
The details of the attribute are defined in Section 5.2. The details of the attribute are defined in Section 5.2.
15.2.2. max-message-size 15.2.2. max-message-size
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 Per this specification, a new IANA registry has been created,
document.] following the procedures in [RFC8126], for the namespace associated
with the "UDP/DTLS/SCTP" and "TCP/DTLS/SCTP" protocol identifiers.
This specification creates a new IANA registry, following the Each fmt value describes the usage of an entire SCTP association,
procedures in [RFC5226], for the namespace associated with the including all SCTP streams associated with the SCTP association.
'UDP/DTLS/SCTP' and 'TCP/DTLS/SCTP' protocol identifiers. Each fmt
value describes the usage of an entire SCTP association, including
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
scope of this specification. | the scope of this specification.
The fmt value, "association-usage", used with these "proto" values is The fmt value "association-usage" used with these "proto" values 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 [RFC8126].
IANA is asked to add initial values to the registry.
|----------------------------------------------------------|
| name | Reference |
|----------------------------------------------------------|
| webrtc-datachannel | draft-ietf-rtcweb-data-protocol-xx, |
| | RFCXXX |
|----------------------------------------------------------|
[RFC EDITOR NOTE: Please hold the publication of this draft
until draft-ietf-rtcweb-data-protocol has been published as an RFC.
Then, replace the reference to draft-ietf-rtcweb-data-protocol
with the RFC number.]
[RFC EDITOR NOTE: Please replace RFCXXXX with the RFC number
of this document.]
Figure 1
16. Acknowledgments
The authors wish to thank Harald Alvestrand, Randell Jesup, Paul
Kyzivat, Michael Tuexen, Juergen Stoetzer-Bradler, Flemming Andreasen
and Ari Keranen for their comments and useful feedback. Ben Campbell
provided comments as part of his AD review. Brian Carpenter
performed the Gen-ART review.
17.
[RFC EDITOR NOTE: Please remove this section when publishing]
Changes from draft-ietf-mmusic-sctp-sdp-25
o SDP 'dtls-id' attribute re-named to 'tls-id'.
Changes from draft-ietf-mmusic-sctp-sdp-24
o Minor editorial fix by Roman.
Changes from draft-ietf-mmusic-sctp-sdp-23
o Changes based on IESG review.
o - Proto value clarifications.
Changes from draft-ietf-mmusic-sctp-sdp-22
o Changes based on Gen-ART review by Brian Carpenter.
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
o Informative reference to draft-ietf-rtcweb-data-protocol added.
Changes from draft-ietf-mmusic-sctp-sdp-19
o Changes based on WG chair comments from Flemming Andreasen.
Changes from draft-ietf-mmusic-sctp-sdp-18
o Changes based on WGLC comments from Paul Kyzivat.
Changes from draft-ietf-mmusic-sctp-sdp-17
o Removal of 'SCTP'.
o Document title changed.
o Disallow usage of SDP 'setup' attribute 'holdconn' value.
o Roman Shpount added as co-editor.
Changes from draft-ietf-mmusic-sctp-sdp-15
o Chapter about SCTP, DTLS and TCP association/connection management
modified.
o Removal of SCTP/DTLS.
Changes from draft-ietf-mmusic-sctp-sdp-14
o Changes based on WGLC comments from Magnus Westerlund.
o - ABNF clarification that token and port are defined in RFC4566.
o - Specify 40 as maximum digit character length for the SDP max-
message-size value.
o - Editorial clarification.
o Changes based on discussions at IETF#92.
o - Specify that all ICE candidate pairs belong to the same DTLS
association.
Changes from draft-ietf-mmusic-sctp-sdp-13
o Changes based on comments from Paul Kyzivat.
o - Text preventing usage of well-known ports removed.
o - Editorial clarification.
Changes from draft-ietf-mmusic-sctp-sdp-12
o Mux category rules added for new SDP attributes.
o Reference to draft-ietf-mmusic-sdp-mux-attributes added.
o Changes based on comments from Roman Shpount:
o - Specify that fingerprint or setup roles must not be modified,
unless underlying transport protocol is also modified.
o Changes based on comments from Ari Keranen:
o - Editorial corrections.
o Changes based on comments from Flemming Andreasen:
o - Clarify that, if UDP/DTLS/SCTP or TCP/DTLS/SCTP is used, the
DTLS association is established before the SCTP association.
o - Clarify that max-message-size value is given in bytes, and that
different values can be used per direction.
o - Section on fmtp attribute removed.
o - Editorial corrections.
Changes from draft-ietf-mmusic-sctp-sdp-11
o Example added.
Changes from draft-ietf-mmusic-sctp-sdp-10
o SDP max-message-size attribute added to IANA considerations.
o Changes based on comments from Paul Kyzivat:
o - Text about max message size removed from fmtp attribute section.
Changes from draft-ietf-mmusic-sctp-sdp-09
o 'DTLS/SCTP' split into 'UDP/DTLS/SCTP' and 'TCP/DTLS/SCTP'
o Procedures for realizing UDP/DTLS/SCTP- and TCP/DTLS/SCTP
transports added.
Changes from draft-ietf-mmusic-sctp-sdp-08
o Default SCTP port removed:
o - Usage of SDP sctp-port attribute mandatory.
o SDP max-message-size attribute defined:
o - Attribute definition.
o - SDP Offer/Answer procedures. IANA has added the following initial values to the registry.
o Text about SDP direction attributes added. +====================+====================+
| Name | Reference |
+====================+====================+
| webrtc-datachannel | RFC 8832, RFC 8841 |
+--------------------+--------------------+
+--------------------+--------------------+
o Text about TLS role determination added. Table 3: IANA Initial Values
18. References 16. References
18.1. Normative References 16.1. Normative References
[RFC0793] Postel, J., "Transmission Control Protocol", STD 7, [RFC0793] Postel, J., "Transmission Control Protocol", STD 7,
RFC 793, DOI 10.17487/RFC0793, September 1981, RFC 793, DOI 10.17487/RFC0793, September 1981,
<http://www.rfc-editor.org/info/rfc793>. <https://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>. <https://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>. <https://www.rfc-editor.org/info/rfc3264>.
[RFC4145] Yon, D. and G. Camarillo, "TCP-Based Media Transport in [RFC4145] Yon, D. and G. Camarillo, "TCP-Based Media Transport in
the Session Description Protocol (SDP)", RFC 4145, the Session Description Protocol (SDP)", RFC 4145,
DOI 10.17487/RFC4145, September 2005, DOI 10.17487/RFC4145, September 2005,
<http://www.rfc-editor.org/info/rfc4145>. <https://www.rfc-editor.org/info/rfc4145>.
[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, <https://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, <https://www.rfc-editor.org/info/rfc4571>.
[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>. <https://www.rfc-editor.org/info/rfc4960>.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
DOI 10.17487/RFC5226, May 2008,
<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, <https://www.rfc-editor.org/info/rfc6347>.
[RFC6544] Rosenberg, J., Keranen, A., Lowekamp, B., and A. Roach, [RFC6544] Rosenberg, J., Keranen, A., Lowekamp, B. B., and A. B.
"TCP Candidates with Interactive Connectivity Roach, "TCP Candidates with Interactive Connectivity
Establishment (ICE)", RFC 6544, DOI 10.17487/RFC6544, Establishment (ICE)", RFC 6544, DOI 10.17487/RFC6544,
March 2012, <http://www.rfc-editor.org/info/rfc6544>. March 2012, <https://www.rfc-editor.org/info/rfc6544>.
[RFC8122] Lennox, J. and C. Holmberg, "Connection-Oriented Media [RFC8122] Lennox, J. and C. Holmberg, "Connection-Oriented Media
Transport over the Transport Layer Security (TLS) Protocol Transport over the Transport Layer Security (TLS) Protocol
in the Session Description Protocol (SDP)", RFC 8122, in the Session Description Protocol (SDP)", RFC 8122,
DOI 10.17487/RFC8122, March 2017, DOI 10.17487/RFC8122, March 2017,
<http://www.rfc-editor.org/info/rfc8122>. <https://www.rfc-editor.org/info/rfc8122>.
[I-D.ietf-mmusic-dtls-sdp] [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Holmberg, C. and R. Shpount, "Using the SDP Offer/Answer Writing an IANA Considerations Section in RFCs", BCP 26,
Mechanism for DTLS", draft-ietf-mmusic-dtls-sdp-24 (work RFC 8126, DOI 10.17487/RFC8126, June 2017,
in progress), April 2017. <https://www.rfc-editor.org/info/rfc8126>.
[I-D.ietf-tsvwg-sctp-dtls-encaps] [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
Tuexen, M., Stewart, R., Jesup, R., and S. Loreto, "DTLS 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
Encapsulation of SCTP Packets", draft-ietf-tsvwg-sctp- May 2017, <https://www.rfc-editor.org/info/rfc8174>.
dtls-encaps-09 (work in progress), January 2015.
[I-D.ietf-mmusic-sdp-mux-attributes] [RFC8261] Tuexen, M., Stewart, R., Jesup, R., and S. Loreto,
Nandakumar, S., "A Framework for SDP Attributes when "Datagram Transport Layer Security (DTLS) Encapsulation of
Multiplexing", draft-ietf-mmusic-sdp-mux-attributes-16 SCTP Packets", RFC 8261, DOI 10.17487/RFC8261, November
(work in progress), December 2016. 2017, <https://www.rfc-editor.org/info/rfc8261>.
18.2. Informative References [RFC8842] Holmberg, C. and R. Shpount, "Session Description Protocol
(SDP) Offer/Answer Considerations for Datagram Transport
Layer Security (DTLS) and Transport Layer Security (TLS)",
RFC 8842, DOI 10.17487/RFC8842, January 2021,
<https://www.rfc-editor.org/info/rfc8842>.
[RFC5245] Rosenberg, J., "Interactive Connectivity Establishment [RFC8859] Nandakumar, S., "A Framework for Session Description
(ICE): A Protocol for Network Address Translator (NAT) Protocol (SDP) Attributes When Multiplexing", RFC 8859,
Traversal for Offer/Answer Protocols", RFC 5245, DOI 10.17487/RFC8859, January 2021,
DOI 10.17487/RFC5245, April 2010, <https://www.rfc-editor.org/info/rfc8859>.
<http://www.rfc-editor.org/info/rfc5245>.
[I-D.ietf-rtcweb-data-channel] 16.2. Informative References
Jesup, R., Loreto, S., and M. Tuexen, "WebRTC Data
Channels", draft-ietf-rtcweb-data-channel-13 (work in
progress), January 2015.
[I-D.ietf-mmusic-data-channel-sdpneg] [RFC8445] Keranen, A., Holmberg, C., and J. Rosenberg, "Interactive
Drage, K., Makaraju, M., Stoetzer-Bradler, J., Ejzak, R., Connectivity Establishment (ICE): A Protocol for Network
and J. Marcon, "SDP-based Data Channel Negotiation", Address Translator (NAT) Traversal", RFC 8445,
draft-ietf-mmusic-data-channel-sdpneg-12 (work in DOI 10.17487/RFC8445, July 2018,
progress), March 2017. <https://www.rfc-editor.org/info/rfc8445>.
[I-D.ietf-rtcweb-data-protocol] [RFC8831] Jesup, R., Loreto, S., and M. Tüxen, "WebRTC Data
Jesup, R., Loreto, S., and M. Tuexen, "WebRTC Data Channel Channels", RFC 8831, DOI 10.17487/RFC8831, January 2021,
Establishment Protocol", draft-ietf-rtcweb-data- <https://www.rfc-editor.org/info/rfc8831>.
protocol-09 (work in progress), January 2015.
[RFC8832] Jesup, R., Loreto, S., and M. Tüxen, "WebRTC Data Channel
Establishment Protocol", RFC 8832, DOI 10.17487/RFC8832,
January 2021, <https://www.rfc-editor.org/info/rfc8832>.
[RFC8864] Drage, K., Makaraju, M., Ejzak, R., Marcon, J., and R.
Even, Ed., "Negotiation Data Channels Using the Session
Description Protocol (SDP)", RFC 8864,
DOI 10.17487/RFC8864, January 2021,
<https://www.rfc-editor.org/info/rfc8864>.
Acknowledgements
The authors wish to thank Harald Alvestrand, Randell Jesup, Paul
Kyzivat, Michael Tüxen, Juergen Stoetzer-Bradler, Flemming Andreasen,
and Ari Keränen for their comments and useful feedback. Ben Campbell
provided comments as part of his Area Director review. Brian
Carpenter performed the Gen-ART review.
Authors' Addresses Authors' Addresses
Christer Holmberg Christer Holmberg
Ericsson Ericsson
Hirsalantie 11 Hirsalantie 11
Jorvas 02420 FI-02420 Jorvas
Finland Finland
Email: christer.holmberg@ericsson.com Email: christer.holmberg@ericsson.com
Roman Shpount Roman Shpount
TurboBridge TurboBridge
4905 Del Ray Avenue, Suite 300 4905 Del Ray Avenue, Suite 300
Bethesda, MD 20814 Bethesda, MD 20814
USA United States of America
Phone: +1 (240) 292-6632 Phone: +1 (240) 292-6632
Email: rshpount@turbobridge.com Email: rshpount@turbobridge.com
Salvatore Loreto Salvatore Loreto
Ericsson Ericsson
Hirsalantie 11 Grönlandsgatan 31
Jorvas 02420 Kista
Finland Sweden
Email: Salvatore.Loreto@ericsson.com Email: Salvatore.Loreto@ericsson.com
Gonzalo Camarillo Gonzalo Camarillo
Ericsson Ericsson
Hirsalantie 11 Hirsalantie 11
Jorvas 02420 FI-02420 Jorvas
Finland Finland
Email: Gonzalo.Camarillo@ericsson.com Email: Gonzalo.Camarillo@ericsson.com
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