draft-ietf-mmusic-sctp-sdp-17.txt   draft-ietf-mmusic-sctp-sdp-18.txt 
MMUSIC C. Holmberg MMUSIC C. Holmberg
Internet-Draft S. Loreto Internet-Draft Ericsson
Intended status: Standards Track G. Camarillo Intended status: Standards Track R. Shpount
Expires: March 3, 2017 Ericsson Expires: April 10, 2017 TurboBridge
August 30, 2016 S. Loreto
G. Camarillo
Ericsson
October 7, 2016
Stream Control Transmission Protocol (SCTP)-Based Media Transport in the Session Description Protocol (SDP) Offer/Answer Procedures For Stream
Session Description Protocol (SDP) Control Transmission Protocol (SCTP) over Datagram Transport Layer
draft-ietf-mmusic-sctp-sdp-17 Security (DTLS) Transport.
draft-ietf-mmusic-sctp-sdp-18
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
on top of the Datagram Transport Layer Security (DTLS) protocol,
referred to as SCTP-over-DTLS.
This specification describes how to describe SCTP associations using This specification defines the following new Session Description
the Session Description Protocol (SDP), and defines the following new Protocol (SDP) protocol identifiers (proto values):'UDP/DTLS/SCTP'
SDP Media Description protocol identifiers (proto values):'SCTP', and 'TCP/DTLS/SCTP'. This specification also specifies how to use
'UDP/DTLS/SCTP' and 'TCP/DTLS/SCTP'. the new proto values with the SDP Offer/Answer mechanism for
negotiating SCTP-over-DTLS associations.
The specification also describes how to use the new proto values
together with the SDP Offer/Answer mechanism in order to negotiate
and establish SCTP associations, and how to indicate the SCTP
application usage.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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 March 3, 2017. This Internet-Draft will expire on April 10, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2016 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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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. SCTP Terminology . . . . . . . . . . . . . . . . . . . . . . 4 3. SCTP Terminology . . . . . . . . . . . . . . . . . . . . . . 4
4. SDP Media Descriptions . . . . . . . . . . . . . . . . . . . 4 4. SDP Media Descriptions . . . . . . . . . . . . . . . . . . . 4
4.1. General . . . . . . . . . . . . . . . . . . . . . . . . . 4 4.1. General . . . . . . . . . . . . . . . . . . . . . . . . . 4
4.2. Protocol Identifiers . . . . . . . . . . . . . . . . . . 5 4.2. Protocol Identifiers . . . . . . . . . . . . . . . . . . 5
4.3. Media Format Management . . . . . . . . . . . . . . . . . 5 4.3. Media Format Management . . . . . . . . . . . . . . . . . 5
4.4. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . 5 4.4. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . 6
4.4.1. General . . . . . . . . . . . . . . . . . . . . . . . 6 4.4.1. General . . . . . . . . . . . . . . . . . . . . . . . 6
4.4.2. ABNF . . . . . . . . . . . . . . . . . . . . . . . . 6 4.4.2. ABNF . . . . . . . . . . . . . . . . . . . . . . . . 6
4.5. Example . . . . . . . . . . . . . . . . . . . . . . . . . 6 4.5. Example . . . . . . . . . . . . . . . . . . . . . . . . . 6
5. SDP 'sctp-port' Attribute . . . . . . . . . . . . . . . . . . 6 5. SDP 'sctp-port' Attribute . . . . . . . . . . . . . . . . . . 6
5.1. General . . . . . . . . . . . . . . . . . . . . . . . . . 6 5.1. General . . . . . . . . . . . . . . . . . . . . . . . . . 6
5.2. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . 7 5.2. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . 7
5.3. Mux Category . . . . . . . . . . . . . . . . . . . . . . 7 5.3. Mux Category . . . . . . . . . . . . . . . . . . . . . . 7
6. SDP 'max-message-size' Attribute . . . . . . . . . . . . . . 7 6. SDP 'max-message-size' Attribute . . . . . . . . . . . . . . 7
6.1. General . . . . . . . . . . . . . . . . . . . . . . . . . 7 6.1. General . . . . . . . . . . . . . . . . . . . . . . . . . 7
6.2. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . 8 6.2. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . 8
6.3. Mux Category . . . . . . . . . . . . . . . . . . . . . . 8 6.3. Mux Category . . . . . . . . . . . . . . . . . . . . . . 8
7. UDP/DTLS/SCTP Transport Realization . . . . . . . . . . . . . 8 7. UDP/DTLS/SCTP Transport Realization . . . . . . . . . . . . . 8
8. TCP/DTLS/SCTP Transport Realization . . . . . . . . . . . . . 9 8. TCP/DTLS/SCTP Transport Realization . . . . . . . . . . . . . 9
9. Association And Connection Management . . . . . . . . . . . . 9 9. Association And Connection Management . . . . . . . . . . . . 9
9.1. General . . . . . . . . . . . . . . . . . . . . . . . . . 9 9.1. General . . . . . . . . . . . . . . . . . . . . . . . . . 9
9.2. SDP sendrecv/sendonly/recvonly/inactive Attribute . . . . 9 9.2. SDP sendrecv/sendonly/recvonly/inactive Attribute . . . . 9
9.3. SCTP Association . . . . . . . . . . . . . . . . . . . . 9 9.3. SCTP Association . . . . . . . . . . . . . . . . . . . . 9
9.4. DTLS Association (UDP/DTLS/SCTP And TCP/DTLS/SCTP) . . . 10 9.4. DTLS Association (UDP/DTLS/SCTP And TCP/DTLS/SCTP) . . . 10
9.5. TCP Connection (TCP/DTLS/SCTP) . . . . . . . . . . . . . 10 9.5. TCP Connection (TCP/DTLS/SCTP) . . . . . . . . . . . . . 11
10. SDP Offer/Answer Procedures . . . . . . . . . . . . . . . . . 11 10. SDP Offer/Answer Procedures . . . . . . . . . . . . . . . . . 11
10.1. General . . . . . . . . . . . . . . . . . . . . . . . . 11 10.1. General . . . . . . . . . . . . . . . . . . . . . . . . 11
10.2. Generating the Initial SDP Offer . . . . . . . . . . . . 11 10.2. Generating the Initial SDP Offer . . . . . . . . . . . . 11
10.3. Generating the SDP Answer . . . . . . . . . . . . . . . 12 10.3. Generating the SDP Answer . . . . . . . . . . . . . . . 12
10.4. Offerer Processing of the SDP Answer . . . . . . . . . . 12 10.4. Offerer Processing of the SDP Answer . . . . . . . . . . 13
10.5. Modifying the Session . . . . . . . . . . . . . . . . . 13 10.5. Modifying the Session . . . . . . . . . . . . . . . . . 13
11. Multihoming Considerations . . . . . . . . . . . . . . . . . 13 11. Multihoming Considerations . . . . . . . . . . . . . . . . . 14
12. NAT Considerations . . . . . . . . . . . . . . . . . . . . . 14 12. NAT Considerations . . . . . . . . . . . . . . . . . . . . . 14
12.1. General . . . . . . . . . . . . . . . . . . . . . . . . 14 12.1. General . . . . . . . . . . . . . . . . . . . . . . . . 14
12.2. ICE Considerations . . . . . . . . . . . . . . . . . . . 14 12.2. ICE Considerations . . . . . . . . . . . . . . . . . . . 14
13. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 15 13. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 15
13.1. Establishment of UDP/DTLS/SCTP association . . . . . . . 15 13.1. Establishment of UDP/DTLS/SCTP association . . . . . . . 15
14. Security Considerations . . . . . . . . . . . . . . . . . . . 15 14. Security Considerations . . . . . . . . . . . . . . . . . . . 16
15. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16 15. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
15.1. New SDP proto values . . . . . . . . . . . . . . . . . . 16 15.1. New SDP proto values . . . . . . . . . . . . . . . . . . 17
15.2. New SDP Attributes . . . . . . . . . . . . . . . . . . . 16 15.2. New SDP Attributes . . . . . . . . . . . . . . . . . . . 17
15.2.1. sctp-port . . . . . . . . . . . . . . . . . . . . . 16 15.2.1. sctp-port . . . . . . . . . . . . . . . . . . . . . 17
15.2.2. max-message-size . . . . . . . . . . . . . . . . . . 17 15.2.2. max-message-size . . . . . . . . . . . . . . . . . . 18
15.3. association-usage Name Registry . . . . . . . . . . . . 17 15.3. association-usage Name Registry . . . . . . . . . . . . 18
16. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 18 16. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 19
17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
18. References . . . . . . . . . . . . . . . . . . . . . . . . . 20 18. References . . . . . . . . . . . . . . . . . . . . . . . . . 21
18.1. Normative References . . . . . . . . . . . . . . . . . . 20 18.1. Normative References . . . . . . . . . . . . . . . . . . 21
18.2. Informative References . . . . . . . . . . . . . . . . . 22 18.2. Informative References . . . . . . . . . . . . . . . . . 23
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23
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 [RFC4572] extends RFC4145 [RFC4145] for describing TCP-based media
streams that are protected using TLS. 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 transport protocol used to establish associations between two
endpoints. endpoints.
This specification defines how to describe SCTP associations using The Stream Control Transmission Protocol (SCTP) [RFC4960] is a
the Session Description Protocol (SDP) [RFC4566], and defines the transport protocol used to establish associations between two
following new SDP Media Description [RFC4566] protocol identifiers endpoints. [I-D.ietf-tsvwg-sctp-dtls-encaps] specifies how SCTP can
(proto values):'SCTP', 'UDP/DTLS/SCTP' and 'TCP/DTLS/SCTP'. be used on top of the Datagram Transport Layer Security (DTLS)
protocol, referred to as SCTP-over-DTLS.
The specification also describes how to use the new proto values This specification defines the following new Session Description
together with the SDP Offer/Answer mechanism [RFC3264] in order to Protocol (SDP) [RFC4566] protocol identifiers (proto
negotiate and establish SCTP associations, and how to indicate the values):'UDP/DTLS/SCTP' and 'TCP/DTLS/SCTP'. This specification also
SCTP application usage. specifies how to use the new proto values with the SDP Offer/Answer
mechanism [RFC3264] for negotiating SCTP-over-DTLS associations.
NOTE: TLS is designed to run on top of a byte-stream oriented NOTE: TLS is designed to run on top of a byte-stream oriented
transport protocol providing a reliable, in-sequence delivery like transport protocol providing a reliable, in-sequence delivery like
TCP. [RFC6083] presents serious limitations with transporting TLS on TCP. [RFC6083] presents serious limitations with transporting TLS on
top of SCTP. Therefore, defining a mechanism to negotiate media top of SCTP. Therefore, defining a mechanism to negotiate media
streams transported using TLS on top of SCTP, i.e. 'SCTP/TLS', is streams transported using TLS on top of SCTP, i.e., 'SCTP/TLS', is
outside the scope of this specification. In addition, defining a
mechanism to negotiate non-protected SCTP associations is also
outside the scope of this specification. outside the scope of this specification.
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
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another associated SCTP endpoint, within which all user messages are another associated SCTP endpoint, within which all user messages are
delivered in sequence except for those submitted to the unordered delivered in sequence except for those submitted to the unordered
delivery service. delivery service.
SCTP Transport address: A transport address is traditionally defined SCTP Transport address: A transport address is traditionally defined
by a network-layer address, a transport-layer protocol, and a by a network-layer address, a transport-layer protocol, and a
transport-layer port number. In the case of SCTP running over IP, a transport-layer port number. In the case of SCTP running over IP, a
transport address is defined by the combination of an IP address and transport address is defined by the combination of an IP address and
an SCTP port number (where SCTP is the transport protocol). an SCTP port number (where SCTP is the transport protocol).
SCTP-over-DTLS: SCTP used on top of DTLS, as specified in
[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: 'SCTP', 'UDP/DTLS/SCTP' and 'TCP/DTLS/SCTP'. The association: UDP/DTLS/SCTP' and 'TCP/DTLS/SCTP'. The section also
section also describes how an m- line, associated with the proto describes how an m- line, associated with the proto values, is
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 'SCTP', 'UDP/DTLS/SCTP' and 'TCP/DTLS/SCTP' proto values are The 'UDP/DTLS/SCTP' and 'TCP/DTLS/SCTP' proto values are similar to
similar to both the 'UDP' and 'TCP' proto values in that they only both the 'UDP' and 'TCP' proto values in that they only describe the
describe the transport-layer protocol and not the upper-layer transport-layer protocol and not the upper-layer protocol.
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, The m- line fmt value, identifying the application-layer protocol,
MUST be registered by IANA. 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 'SCTP' proto value describes an SCTP association, as defined
in [RFC4960].
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. Use of an existing MIME subtype for the format is managed. Use of an existing MIME subtype for the format is
encouraged. If no MIME subtype exists, it is recommended that a encouraged. If no MIME subtype exists, it is recommended that a
suitable one is registered through the IETF process [RFC6838] suitable one is registered through the IETF process [RFC6838]
[RFC4289] by production of, or reference to, a standards-track RFC [RFC4289] by production of, or reference to, a standards-track RFC
that defines the transport protocol for the format. that defines the transport protocol for the format.
An m- line with a proto value of 'SCTP', 'UDP/DTLS/SCTP' or An m- line with a proto value of UDP/DTLS/SCTP' or 'TCP/DTLS/SCTP'
'TCP/DTLS/SCTP' always describe a single SCTP association. always describe 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.
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
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This section defines the ABNF [RFC5234] for the SDP media description This section defines the ABNF [RFC5234] for the SDP media description
when associated with any of the proto values defined in this when associated with any of the proto values defined in this
document. document.
This specification creates an IANA registry for 'association-usage' This specification creates an IANA registry for 'association-usage'
values. values.
4.4.2. ABNF 4.4.2. ABNF
sctp-m-line = %x6d "=" sctp-m-line = %x6d "="
("application" SP sctp-port SP "SCTP" SP fmt CRLF) /
("application" SP udp-port SP "UDP/DTLS/SCTP" SP fmt CRLF) / ("application" SP udp-port SP "UDP/DTLS/SCTP" SP fmt CRLF) /
("application" SP tcp-port SP "TCP/DTLS/SCTP" SP fmt CRLF) ("application" SP tcp-port SP "TCP/DTLS/SCTP" SP fmt CRLF)
sctp-port = port
udp-port = port udp-port = port
tcp-port = port tcp-port = port
fmt = association-usage fmt = association-usage
association-usage = token association-usage = token
token and port as defined in RFC4566 token and port as defined in RFC4566
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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
one of the following proto values: 'SCTP', 'UDP/DTLS/SCTP' or one of the following proto values: 'UDP/DTLS/SCTP' or 'TCP/DTLS/
'TCP/DTLS/SCTP'. Usage of the attribute with other proto values SCTP'. Usage of the attribute with other proto values needs to be
needs to be defined in a separate specification. defined in a separate specification.
6.2. Syntax 6.2. Syntax
The ABNF for the SDP 'max-message-size' attribute is: The ABNF for the SDP 'max-message-size' attribute is:
max-message-size-attr = "a=max-message-size:" max-message-size max-message-size-attr = "a=max-message-size:" max-message-size
max-message-size = 1*40DIGIT max-message-size = 1*40DIGIT
Leading zeroes MUST NOT be used. Leading zeroes MUST NOT be used.
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 SPECIAL.
The mux rules depends on the proto value of the associated m- line. The mux rules depends on the proto value of the associated m- line.
If the proto value is 'SCTP' the rules are identical to the rules
associated with the TRANSPORT mux category.
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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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 mange an SCTP association, DTLS
association and TCP connection using SDP attributes. association and TCP connection using SDP attributes.
In case of UDP/DTLS/SCTP and TCP/DTLS/SCTP the SCTP association, DTLS In case of UDP/DTLS/SCTP and TCP/DTLS/SCTP the SCTP association, DTLS
association and TCP connection are managed independetly for each association and TCP connection are managed independently for each
other. An assocation/connection can be re-established without other. An association/connection can be re-established without
impacting other assocations/connections. impacting other associations/connections.
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
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 semantics of these attributes for an
SCTP association usage have been defined, SDP direction attributes SCTP association usage have been defined, SDP direction attributes
MUST be discarded if present. MUST be discarded if present.
skipping to change at page 10, line 16 skipping to change at page 10, line 14
As both SCTP endpoints take the 'active' role, this specification As both SCTP endpoints take the 'active' role, this specification
does not define usage of the SDP 'setup' attribute [RFC4145] for does not define usage of the SDP 'setup' attribute [RFC4145] for
SCTP. SCTP.
NOTE: The procedure above is different from TCP, where one endpoint NOTE: The procedure above is different from TCP, where one endpoint
takes the 'active' role, the other endpoint takes the 'passive' role, takes the 'active' role, the other endpoint takes the 'passive' role,
and only the 'active' endpoint initiates the TCP connection and only the 'active' endpoint initiates the TCP connection
[RFC4145]. [RFC4145].
NOTE: If the underlying transport protocol is UDP or TCP (UDP/DTLS/ NOTE: In case of SCTP-over-DTLS, when the SCTP association is
SCTP or TCP/DTLS/SCTP), when the SCTP association is established it established it is assumed that any NAT traversal procedures for the
is assumed that any NAT traversal procedures for the underlying underlying transport protocol (UDP or TCP) has successfully been
transport protocol has successfully been performed. performed.
Usage of the SDP 'connection' attribute [RFC4145] is not defined for Usage of the SDP 'connection' attribute [RFC4145] is not defined for
SCTP. In order to trigger the re-establishment of an SCTP SCTP. In order to trigger the closure and re-establishment of an
association, the SDP 'sctp-port' attribute (Section 5) is used to SCTP association, the SDP 'sctp-port' attribute (Section 5) is used
indicate a new (different than the ones currently used) SCTP ports. to indicate a new (different than the ones currently used) SCTP port.
NOTE: This specification does not define procedures for re- Alternatively, an SCTP association can be closed using the SDP 'sctp-
establishing an SCTP association using the SCTP ports currently used port' attribute with a zero attribute value. Later, the SCTP
for the SCTP association. association can be re-established using the procedures in this
section for establishing an SCTP association.
SCTP associations might be closed without SDP signalling, e.g, in
case of a failure. When such SCTP association is re-established the
SCTP endpoints MUST use the procedures in this section for
establishing an SCTP association. New (different than the ones
currently used) SCTP ports MUST be used.
NOTE: Closing and re-establishing the SCTP association using the SDP
'sctp-port' attribute will not impact the 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)
An DTLS association is managed according to the procedures in An 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') [RFC4572].
NOTE: The SDP 'setup' attribute is used both to negotiate both the NOTE: The SDP 'setup' attribute is used both to negotiate both the
DTLS roles and the TCP roles (Section 9.5). DTLS roles and the TCP roles (Section 9.5).
skipping to change at page 11, line 5 skipping to change at page 11, line 13
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.
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. connection, or create a new one. The SDP 'setup' attribute
'holdconn' value MUST NOT be used.
NOTE: A change of the TCP roles will also trigger a re-establishment NOTE: A change of the TCP roles will also trigger a re-establishment
of the DTLS association, according to the procedures in of the DTLS association, according to the procedures in
[I-D.ietf-mmusic-dtls-sdp]. [I-D.ietf-mmusic-dtls-sdp].
NOTE: As specified in [I-D.ietf-mmusic-dtls-sdp], usage of the SDP
'setup' attribute 'holdconn' value is not allowed. Therefore this
specification also forbids usage of the attribute value for 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 association. Unless explicitly negotiating and establishing an SCTP-over-DTLS association. Unless
stated, the procedures apply to SCTP, UDP/DTLS/SCTP and TCP/DTLS/ explicitly stated, the procedures apply to both the 'UDP/DTLS/SCTP'
SCTP. and 'TCP/DTLS/SCTP' m- line proto values.
In case of UDP/DTLS/SCTP or TCP/DTLS/SCTP, each endpoint MUST Each endpoint MUST associate one or more certificate fingerprints,
associate one or more certificate fingerprints, using the SDP using the SDP 'fingerprint' attribute with the m- line, following the
'fingerprint' attribute with the m- line, following the procedures in procedures in [RFC4572] and [I-D.ietf-mmusic-4572-update].
[RFC4572] and [I-D.ietf-mmusic-4572-update].
The authentication certificates are interpreted and validated as The authentication certificates are interpreted and validated as
defined in [RFC4572]. Self-signed certificates can be used securely, defined in [RFC4572]. 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 [RFC4572]. defined in [RFC4572].
In case of UDP/DTLS/SCTP or TCP/DTLS/SCTP, each endpoint MUST Each endpoint MUST associate an SDP 'dtls-id' attribute with the m-
associate an SDP 'dtls-id' attribute with the m- line, following the line, following the procedures in [I-D.ietf-mmusic-dtls-sdp].
procedures in [I-D.ietf-mmusic-dtls-sdp].
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, in the case of UDP/DTLS/SCTP or TCP/DTLS/SCTP, associate an o MUST associate an SDP setup attribute, with an 'actpass' value,
SDP setup attribute, with an 'actpass' value, with the m- line; with the m- line;
o MUST, in the case of UDP/DTLS/SCTP or TCP/DTLS/SCTP, associate an o MUST associate an SDP 'sctp-port' attribute with the m- line;
SDP 'sctp-port' attribute with the m- line;
o MUST, in the case of TCP/DTLS/SCTP, associate an SDP 'connection' o 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 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 association, if the answerer accepts the m- line describing an SCTP-over-DTLS association, if the answerer accepts the
it: association line it:
o MUST insert a corresponding m- line in the answer, with an o MUST insert a corresponding m- line in the answer, with an
identical m- line proto value [RFC3264]; identical m- line proto value [RFC3264];
o MUST, in the case of UDP/DTLS/SCTP or TCP/DTLS/SCTP associate an o MUST associate an SDP 'setup' attribute, with an 'active' or
SDP 'setup' attribute, with an 'active' or 'passive' value, with 'passive' value, with the m- line;
the m- line;
o MUST, in the case of UDP/DTLS/SCTP or TCP/DTLS/SCTP, associate an o MUST associate an SDP 'sctp-port' attribute with the m- line. If
SDP 'sctp-port' attribute with the m- line; and the offer contained a new (different than the one currently used)
SCTP port value the answerer MUST also associate a new SCTP port
value. If the offer contained a zero SCTP port value the answerer
MUST also associate a zero SCTP port value; and
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 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 from the value (if present) in the corresponding m- line of the
offer. offer.
Once the answerer has sent the answer, the answerer MUST, if an SCTP Once the answerer has sent the answer the answerer MUST, if an SCTP
association has yet not been established, or if an existing SCTP association has yet not been established, or if an existing SCTP
association is to be re-established, initiate the establishement of association is to be re-established, initiate the establishment of
the SCTP association. the SCTP association.
In the case of UDP/DTLS/SCTP or TCP/DTLS/SCTP, the answerer follows The answerer follows the procedures in [I-D.ietf-mmusic-dtls-sdp]
the procedures in [I-D.ietf-mmusic-dtls-sdp] regarding the regarding the establishment/re-establishment of the DTLS association.
establishment/re-establishemnt of the DTLS association.
In the case of TCP/DTLS/SCTP, the answerer follows the procedures in In the case of TCP/DTLS/SCTP, the answerer follows the procedures in
[RFC4145] regarding the establishment/re-establishemnt of the TCP [RFC4145] regarding the establishment/re-establishment of the TCP
conection association. connection association.
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 answer,
following the procedures in [RFC3264]. In addition, the answerer following the procedures in [RFC3264]. In addition, the answerer
MUST NOT initiate the establishment of an SCTP association, or a DTLS MUST NOT initiate the establishment of an SCTP association, or a DTLS
association, associated with the m- line. 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, which contains an m- line Once the offerer has received the answer, which contains an m- line
with a non-zero port value, the offerer MUST, if an SCTP association with a non-zero port value, the offerer MUST, if an SCTP association
has yet not been established, or if an existing SCTP association is has yet not been established, or if an existing SCTP association is
to be re-established, initiate the establishement of the SCTP to be re-established, initiate the establishment of the SCTP
association. association.
In the case of UDP/DTLS/SCTP or TCP/DTLS/SCTP, the offerer follows If the SDP 'sctp-port' attribute in the answer contains a zero
the procedures in [I-D.ietf-mmusic-dtls-sdp] regarding the attribute value, the offerer MUST NOT establish an SCTP association.
establishment/re-establishemnt of the DTLS association. If an SCTP association exists, the offerer MUST close it.
The offerer follows the procedures in [I-D.ietf-mmusic-dtls-sdp]
regarding the establishment/re-establishment of the DTLS association.
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 establishment/re-establishemnt of the TCP [RFC4145] regarding the establishment/re-establishment of the TCP
conection association. connection association.
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 offerer
MUST NOT establish a TCP connection, an SCTP association, or a DTLS MUST NOT establish a TCP connection, an SCTP association, or a DTLS
association, associated with the m- line. association, associated with the m- line. If an SCTP association,
DTLS association and/or TCP connection 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 Unless the offerer wants to re-establish an SCTP association, the o If the offerer wants to close and immediately re-establish an
offerer MUST associate an SDP 'sctp-port' attribute, with a new existing SCTP association, the offerer MUST associate an SDP
attribute value, with the m- line; and 'sctp-port' attribute with a new (different than the one currently
used) attribute value. This will not impact the underlying DTLS
association (and TCP connection in case of TCP/DTLS/SCTP).
o If the offerer wants to disable a previously established SCTP o If the offerer wants to close, but not re-establish an existing
association, it MUST assign a zero port value to the m- line SCTP association, the offerer MUST associate an SDP 'sctp-port'
associated with the SCTP association, following the procedures in attribute with a zero attribute value. This will not impact the
underlying DTLS association (and TCP connection in case of
TCP/DTLS/SCTP).
o If the offerer wants to re-establish a previously closed SCTP
association, the offerer MUST associate an SDP 'sctp-port'
attribute with a new (different than the one currently used)
attribute value. If the SCTP association was previously closed
using an SDP 'sctp-port' attribute with a zero attribute value,
the offerer MAY use the same attribute value that was used prior
to the SCTP association was closed. This will not impact the
underlying DTLS association (and TCP connection in case of
TCP/DTLS/SCTP).
o If the offerer wants to close an existing SCTP association, and
the underlying DTLS association (and the underlying TCP connection
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
connection in case of TCP/DTLS/SCTP), following the procedures in
[RFC3264]. [RFC3264].
In the case of UDP/DTLS/SCTP or TCP/DTLS/SCTP, the offer follows the o NOTE: This specification does not define a mechanism for
procedures in [I-D.ietf-mmusic-dtls-sdp] regarding the DTLS explicitly closing an DTLS association while maintaining the
association impacts when modifying a session. overlying SCTP association. However, if a DTLS association is re-
established as a result of some other action
[I-D.ietf-mmusic-dtls-sdp] the SCTP association is not affected.
The offer follows the procedures in [I-D.ietf-mmusic-dtls-sdp]
regarding the DTLS association impacts when modifying a session.
In the case of TCP/DTLS/SCTP, the offer follows the procedures in In the case of TCP/DTLS/SCTP, the offer 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
SCTP supports multihoming. An SCTP endpoint is considered multihomed
if it has more than one IP address on which SCTP can be used. An
SCTP endpoint inform the remote peer about its IP addresses using the
address parameters in the INIT/INIT-ACK chunk. Therefore, when SDP
is used to describe an SCTP association, while the "c=" line contains
the address which was used to negotiate the SCTP association,
multihomed SCTP endpoints might end up using other IP addresses.
If an endpoint removes the IP address [RFC5061] that it offered in
the SDP "c=" line associated with the SCTP association, it MUST send
a new Offer, in which the "c=" line contains an IP address which is
valid within the SCTP association.
NOTE: In some network environments, intermediaries performing gate-
and firewall control using the address information in the SDP "c="
and "m=" lines to authorize media, and will not pass media sent using
other addresses. In such network environments, if an SCTP endpoints
wants to change the address information on which media is sent and
received, it needs to send an updated Offer, in which the SDP "c="
and "m=" lines contain the new address information.
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
SCTP features not present in UDP or TCP, including the checksum When SCTP-over-DTLS is used in NAT environment, it relies on the NAT
(CRC32c) value calculated on the whole packet (rather than just the traversal procedures for the underlying transport protocol (UDP or
header), and multihoming, introduce new challenges for NAT traversal. TCP).
[I-D.ietf-behave-sctpnat] defines an SCTP specific variant of NAT,
which provides similar features of Network Address and Port
Translation (NAPT).
Current NATs typically do not support SCTP. [RFC6951] defines a
mechanism for sending SCTP on top of UDP, which makes it possible to
use SCTP with NATs and firewalls that do not support SCTP.
12.2. ICE Considerations 12.2. ICE Considerations
At the time of writing this specification, no procedures have been When SCTP-over-DTLS is used with UDP based ICE candidates as defined
defined for using ICE [RFC5245] together with SCTP as transport layer in [RFC5245] procedures for UDP/DTLS/SCTP, as defined in Section 7
protocol. Such procedures, including the associated SDP Offer/Answer are used.
procedures, are outside the scope of this specification, and might be
defined in a future specification.
When the transport layer protocol is UDP (UDP/DTLS/SCTP), if ICE is
used, the ICE procedures defined in [RFC5245] are used.
When the transport layer protocol is TCP (TCP/DTLS/SCTP), if ICE is When SCTP-over-DTLS is used with TCP based ICE candidates as defined
used, the ICE procedures defined in [RFC6544] are used. in [RFC6544] procedures for TCP/DTLS/SCTP, as defined in Section 8
are used.
Implementations MUST treat all ICE candidate pairs associated with a Implementations MUST treat all ICE candidate pairs associated with a
an SCTP association on top of a DTLS association as part of the same an SCTP association on top of a DTLS association as part of the same
DTLS association. Thus, there will only be one DTLS handshake even DTLS association. Thus, there will only be one SCTP handshake and
if there are multiple valid candidate pairs, and shifting from one one DTLS handshake even if there are multiple valid candidate pairs,
candidate pair to another will not impact the DTLS association. If and shifting from one candidate pair to another will not impact the
new candidates are added, they will also be part of the same DTLS SCTP or DTLS associations. If new candidates are added, they will
association. also be part of the same SCTP and DTLS associations. When
transitioning between candidate pairs, different candidate pairs can
be currently active in different directions and implementations MUST
be ready to receive 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 in different directions.
When an SDP offer or answer is sent, the proto value MUST match the
transport protocol associated with the default candidate. Hence, if
UDP transport is used for the default candidate the 'UDP/DTLS/SCTP'
proto value MUST be used. If TCP transport is used for the default
candidate the 'TCP/DTLS/SCTP' proto value MUST be used. However, if
an endpoint switch between TCP-based and UDP-based candidates during
a session the endpoint is not required to send an SDP offer in order
to modify that proto value of the associated m- line.
NOTE: The text in the paragraph above only applies when the usage of
ICE has been negotiated. If ICE is not used, the 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: SDP Offer:
m=application 54111 UDP/DTLS/SCTP webrtc-datachannel m=application 54111 UDP/DTLS/SCTP webrtc-datachannel
c=IN IP4 192.0.2.1 c=IN IP4 192.0.2.1
a=dtls-id:abc3dl a=dtls-id:abc3dl
a=setup:actpass a=setup:actpass
a=sctp-port:5000 a=sctp-port:5000
a=max-message-size:100000 a=max-message-size:100000
- The offerer indicates that the usage of the - The offerer indicates that the usage of the
skipping to change at page 16, line 5 skipping to change at page 16, line 40
- 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 [RFC4572] 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, while [RFC4960] defines general SCTP security considerations and
[RFC6083] defines security considerations when using DTLS on top of [I-D.ietf-tsvwg-sctp-dtls-encaps] defines security considerations
SCTP, and [I-D.ietf-tsvwg-sctp-dtls-encaps] defines security when using SCTP on top of DTLS.
considerations 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 [RFC EDITOR NOTE: Please replace RFCXXXX with the RFC number of this
document.] 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 | SCTP | [RFCXXXX] |
| proto | UDP/DTLS/SCTP | [RFCXXXX] | | proto | UDP/DTLS/SCTP | [RFCXXXX] |
| proto | TCP/DTLS/SCTP | [RFCXXXX] | | proto | TCP/DTLS/SCTP | [RFCXXXX] |
+-------+---------------+-----------+ +-------+---------------+-----------+
Table 1: SDP "proto" field values Table 1: SDP "proto" field values
15.2. New SDP Attributes 15.2. New SDP Attributes
15.2.1. sctp-port 15.2.1. sctp-port
skipping to change at page 17, line 10 skipping to change at page 17, line 41
document.] document.]
This document defines a new SDP media-level attribute,'sctp-port', as This document defines a new SDP media-level attribute,'sctp-port', as
follows: follows:
Attribute name: sctp-port Attribute name: sctp-port
Type of attribute: media Type of attribute: media
Mux category: SPECIAL Mux category: SPECIAL
Subject to charset: No Subject to charset: No
Purpose: Indicate the SCTP port value associated Purpose: Indicate the SCTP port value associated
with the SDP Media Description. with 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
15.2.2. max-message-size 15.2.2. max-message-size
[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 document defines a new SDP media-level attribute,'max-message- This document defines a new SDP media-level attribute,'max-message-
size', as follows: size', as follows:
Attribute name: max-message-size Attribute name: max-message-size
Type of attribute: media Type of attribute: media
Mux category: SPECIAL Mux category: SPECIAL
Subject to charset: No Subject to charset: No
Purpose: Indicate the maximum message size that Purpose: Indicate the maximum message size that
an SCTP endpoint is willing to receive an SCTP endpoint is willing to receive
on the SCTP association associated on the SCTP association associated
with the SDP Media Description. with 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
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 "fmt" namespace associated with the
'SCTP', 'UDP/DTLS/SCTP' and 'TCP/DTLS/SCTP' protocol identifiers. 'UDP/DTLS/SCTP' and 'TCP/DTLS/SCTP' protocol identifiers. Each "fmt"
Each "fmt" value describes the usage of an entire SCTP association, value describes the usage of an entire SCTP association, including
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" is The "fmt" value, "association-usage", used with these "proto" 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 |
|----------------------------------------------------------| |----------------------------------------------------------|
[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.]
Figure 1 Figure 1
16. Acknowledgments 16. Acknowledgments
The authors wish to thank Roman Shpount, Harald Alvestrand, Randell The authors wish to thank Harald Alvestrand, Randell Jesup, Paul
Jesup, Paul Kyzivat, Michael Tuexen, Juergen Stoetzer-Bradler, Kyzivat, Michael Tuexen, Juergen Stoetzer-Bradler, Flemming Andreasen
Flemming Andreasen and Ari Keranen for their comments and useful and Ari Keranen for their comments and useful feedback.
feedback.
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-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 Changes from draft-ietf-mmusic-sctp-sdp-15
o Chapter about SCTP, DTLS and TCP association/connection management o Chapter about SCTP, DTLS and TCP association/connection management
modified. modified.
o Removal of SCTP/DTLS. o Removal of SCTP/DTLS.
Changes from draft-ietf-mmusic-sctp-sdp-14 Changes from draft-ietf-mmusic-sctp-sdp-14
o Changes based on WGLC comments from Magnus Westerlund. o Changes based on WGLC comments from Magnus Westerlund.
o - ABNF clarification that token and port are defined in RFC4566. o - ABNF clarification that token and port are defined in RFC4566.
o - Specify 40 as maximum digit character length for the SDP max- o - Specify 40 as maximum digit character length for the SDP max-
message-size value. message-size value.
o - Editorial clarification. o - Editorial clarification.
o Changes based on discussions at IETF#92. o Changes based on discussions at IETF#92.
skipping to change at page 21, line 39 skipping to change at page 22, line 34
[RFC4572] Lennox, J., "Connection-Oriented Media Transport over the [RFC4572] Lennox, J., "Connection-Oriented Media Transport over the
Transport Layer Security (TLS) Protocol in the Session Transport Layer Security (TLS) Protocol in the Session
Description Protocol (SDP)", RFC 4572, Description Protocol (SDP)", RFC 4572,
DOI 10.17487/RFC4572, July 2006, DOI 10.17487/RFC4572, July 2006,
<http://www.rfc-editor.org/info/rfc4572>. <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>.
[RFC5061] Stewart, R., Xie, Q., Tuexen, M., Maruyama, S., and M.
Kozuka, "Stream Control Transmission Protocol (SCTP)
Dynamic Address Reconfiguration", RFC 5061,
DOI 10.17487/RFC5061, September 2007,
<http://www.rfc-editor.org/info/rfc5061>.
[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>.
[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax [RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, Specifications: ABNF", STD 68, RFC 5234,
DOI 10.17487/RFC5234, January 2008, DOI 10.17487/RFC5234, January 2008,
<http://www.rfc-editor.org/info/rfc5234>. <http://www.rfc-editor.org/info/rfc5234>.
[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>.
[RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type [RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type
Specifications and Registration Procedures", BCP 13, Specifications and Registration Procedures", BCP 13,
RFC 6838, DOI 10.17487/RFC6838, January 2013, RFC 6838, DOI 10.17487/RFC6838, January 2013,
<http://www.rfc-editor.org/info/rfc6838>. <http://www.rfc-editor.org/info/rfc6838>.
[I-D.ietf-mmusic-4572-update] [I-D.ietf-mmusic-4572-update]
Holmberg, C., "Updates to RFC 4572", draft-ietf-mmusic- Holmberg, C., "SDP Fingerprint Attribute Usage
4572-update-05 (work in progress), June 2016. Clarifications", draft-ietf-mmusic-4572-update-07 (work in
progress), September 2016.
[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-14 (work Mechanism for DTLS", draft-ietf-mmusic-dtls-sdp-14 (work
in progress), July 2016. in progress), July 2016.
[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.
skipping to change at page 23, line 16 skipping to change at page 23, line 48
Transport Layer Security (DTLS) for Stream Control Transport Layer Security (DTLS) for Stream Control
Transmission Protocol (SCTP)", RFC 6083, Transmission Protocol (SCTP)", RFC 6083,
DOI 10.17487/RFC6083, January 2011, DOI 10.17487/RFC6083, January 2011,
<http://www.rfc-editor.org/info/rfc6083>. <http://www.rfc-editor.org/info/rfc6083>.
[RFC6544] Rosenberg, J., Keranen, A., Lowekamp, B., and A. Roach, [RFC6544] Rosenberg, J., Keranen, A., Lowekamp, B., and A. Roach,
"TCP Candidates with Interactive Connectivity "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, <http://www.rfc-editor.org/info/rfc6544>.
[RFC6951] Tuexen, M. and R. Stewart, "UDP Encapsulation of Stream
Control Transmission Protocol (SCTP) Packets for End-Host
to End-Host Communication", RFC 6951,
DOI 10.17487/RFC6951, May 2013,
<http://www.rfc-editor.org/info/rfc6951>.
[I-D.ietf-behave-sctpnat]
Stewart, R., Tuexen, M., and I. Ruengeler, "Stream Control
Transmission Protocol (SCTP) Network Address Translation",
draft-ietf-behave-sctpnat-09 (work in progress), September
2013.
Authors' Addresses Authors' Addresses
Christer Holmberg Christer Holmberg
Ericsson Ericsson
Hirsalantie 11 Hirsalantie 11
Jorvas 02420 Jorvas 02420
Finland Finland
Email: christer.holmberg@ericsson.com Email: christer.holmberg@ericsson.com
Roman Shpount
TurboBridge
4905 Del Ray Avenue, Suite 300
Bethesda, MD 20814
USA
Phone: +1 (240) 292-6632
Email: rshpount@turbobridge.com
Salvatore Loreto Salvatore Loreto
Ericsson Ericsson
Hirsalantie 11 Hirsalantie 11
Jorvas 02420 Jorvas 02420
Finland Finland
Email: Salvatore.Loreto@ericsson.com Email: Salvatore.Loreto@ericsson.com
Gonzalo Camarillo Gonzalo Camarillo
Ericsson Ericsson
Hirsalantie 11 Hirsalantie 11
Jorvas 02420 Jorvas 02420
Finland Finland
Email: Gonzalo.Camarillo@ericsson.com Email: Gonzalo.Camarillo@ericsson.com
 End of changes. 70 change blocks. 
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