Network Working Group R. Jesup
Internet-Draft WorldGate Communications
Intended status: Standards Track S. Loreto
Expires: August 20, 2013 Ericsson
R. Stewart
Adara Networks
M. Tuexen
Muenster Univ. of Appl. Sciences
February 16, 2013
DTLS Encapsulation of SCTP Packets for RTCWEB
draft-ietf-tsvwg-sctp-dtls-encaps-00.txt
Abstract
The Stream Control Transmission Protocol (SCTP) is a transport
protocol originally defined to run on top of the network protocols
IPv4 or IPv6. This memo document specifies how SCTP can be used on
top of the Datagram Transport Layer Security (DTLS) protocol. SCTP
over DTLS is used by the RTCWeb protocol suite for transporting non-
media data between browsers.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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Internet-Drafts are draft documents valid for a maximum of six months
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 20, 2013.
Copyright Notice
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document authors. All rights reserved.
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Provisions Relating to IETF Documents
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Encapsulation and Decapsulation Procedure . . . . . . . . . . . 3
4. DTLS Considerations . . . . . . . . . . . . . . . . . . . . . . 4
5. SCTP Considerations . . . . . . . . . . . . . . . . . . . . . . 4
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
7. Security Considerations . . . . . . . . . . . . . . . . . . . . 6
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 6
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
9.1. Normative References . . . . . . . . . . . . . . . . . . . 6
9.2. Informative References . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7
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1. Introduction
1.1. Overview
The Stream Control Transmission Protocol (SCTP) as defined in
[RFC4960] is a transport protocol running on top of the network
protocols IPv4 or IPv6. This memo document specifies how SCTP can be
used on top of the Datagram Transport Layer Security (DTLS) protocol.
SCTP over DTLS is used by the RTCWeb protocol suite (see
[I-D.ietf-rtcweb-overview] for an overview) for transporting non-
media data between browsers. The architecture of this stack is
described in [I-D.jesup-rtcweb-data].
1.2. Terminology
This document uses the following terms:
Association: An SCTP association.
Stream: A unidirectional stream of an SCTP association. It is
uniquely identified by a stream identifier.
1.3. Abbreviations
DTLS: Datagram Transport Layer Security.
MTU: Maximum Transmission Unit.
PPID: Payload Protocol Identifier.
SCTP: Stream Control Transmission Protocol.
TCP: Transmission Control Protocol.
TLS: Transport Layer Security.
2. Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
3. Encapsulation and Decapsulation Procedure
When an SCTP packet is sent down to the DTLS layer, the complete SCTP
packet, consisting of the SCTP common header and a number of SCTP
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chunks, MUST be handled as the payload of the application layer
protocol of DTLS. When the DTLS layer has processed a DTLS record
containing a message of the application layer protocol, the payload
MUST be given up to the SCTP layer. The SCTP layer expects an SCTP
common header followed by a number of SCTP chunks.
4. DTLS Considerations
The DTLS implementation MUST be based on [RFC6347].
If path MTU discovery is performed by the DTLS layer, the method
described in [RFC4821] MUST be used. For probe packets, the
extension defined in [RFC6520] MUST be used.
If path MTU discovery is performed by the SCTP layer and IPv4 is used
as the network layer protocol, the DTLS implementation MUST allow the
DTLS user to enforce that the corresponding IPv4 packet is sent with
the DF bit set.
SCTP performs segmentation and reassembly based on the path MTU.
Therefore the DTLS layer MUST NOT use any compression algorithm.
5. SCTP Considerations
5.1. Base Protocol
SCTP as specified in [RFC4960] is used. However, the following
restrictions are necessary to reflect that the lower layer is the
connection oriented protocol DTLS instead of the connection less
protocol IPv4 and IPv6:
o A DTLS connection MUST be established before an SCTP association
can be set up.
o All associations MUST be single-homed.
o The INIT and INIT-ACK chunk MUST NOT contain any IPv4 Address or
IPv6 Address parameters. The INIT chunk MUST NOT contain the
Supported Address Types parameter.
o The implementation MUST NOT rely on processing ICMP or ICMPv6
packets. This applies in particular to path MTU discovery when
performed by SCTP.
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5.2. Padding Extension
The padding extension defined in [RFC4820] MUST be supported and used
for probe packets when performing path MTU discovery as specified in
[RFC4821].
5.3. Dynamic Address Reconfiguration Extension
The SCTP implementation MUST support the Supported Extensions
Parameter defined in [RFC5061] to signal the support of the SCTP
stream reset extension (see Section 5.6). The other functionality
described in [RFC5061] MUST NOT be used.
5.4. SCTP Authentication Extension
The SCTP authentication extension defined in [RFC4895] is not
required.
5.5. Partial Reliability Extension
The SCTP implementation MUST support the extension defined in
[RFC3758].
The SCTP implementation SHOULD support the following PR-SCTP
policies:
o A user message is abandoned after a user specified lifetime.
o A user message is abandoned if the number of retransmissions
exceeds a user specified threshold.
5.6. Stream Reset Extension
The SCTP implementation MUST support the SCTP stream reset extension
defined in [RFC6525]. It is used to reset streams and add streams
during the lifetime of the SCTP association.
5.7. Large User Message Extension
SCTP as defined in [RFC4960] does not support the multiplexing of
large user messages that need to be fragmented and reassembled by the
SCTP layer. To overcome this limitation, the SCTP implementation
SHOULD support an extension, which has to be defined.
5.8. Congestion Control
In addition to the TCP-like congestion control specified in
[RFC4960], other congestion control algorithms MAY be provided. For
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example, it might be helpful to use a congestion control which does
not increase the queueing delay substantially (see [RFC6817] for an
example).
6. IANA Considerations
This document requires no actions from IANA.
7. Security Considerations
This document does not add any additional security considerations in
addition to the ones given in [RFC4960], [RFC3758], [RFC6525], and
[RFC6347].
8. Acknowledgments
The authors wish to thank XXX for their invaluable comments.
9. References
9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3758] Stewart, R., Ramalho, M., Xie, Q., Tuexen, M., and P.
Conrad, "Stream Control Transmission Protocol (SCTP)
Partial Reliability Extension", RFC 3758, May 2004.
[RFC4820] Tuexen, M., Stewart, R., and P. Lei, "Padding Chunk and
Parameter for the Stream Control Transmission Protocol
(SCTP)", RFC 4820, March 2007.
[RFC4821] Mathis, M. and J. Heffner, "Packetization Layer Path MTU
Discovery", RFC 4821, March 2007.
[RFC4895] Tuexen, M., Stewart, R., Lei, P., and E. Rescorla,
"Authenticated Chunks for the Stream Control Transmission
Protocol (SCTP)", RFC 4895, August 2007.
[RFC4960] Stewart, R., "Stream Control Transmission Protocol",
RFC 4960, September 2007.
[RFC5061] Stewart, R., Xie, Q., Tuexen, M., Maruyama, S., and M.
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Kozuka, "Stream Control Transmission Protocol (SCTP)
Dynamic Address Reconfiguration", RFC 5061,
September 2007.
[RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer
Security Version 1.2", RFC 6347, January 2012.
[RFC6520] Seggelmann, R., Tuexen, M., and M. Williams, "Transport
Layer Security (TLS) and Datagram Transport Layer Security
(DTLS) Heartbeat Extension", RFC 6520, February 2012.
[RFC6525] Stewart, R., Tuexen, M., and P. Lei, "Stream Control
Transmission Protocol (SCTP) Stream Reconfiguration",
RFC 6525, February 2012.
9.2. Informative References
[RFC6817] Shalunov, S., Hazel, G., Iyengar, J., and M. Kuehlewind,
"Low Extra Delay Background Transport (LEDBAT)", RFC 6817,
December 2012.
[I-D.ietf-rtcweb-overview]
Alvestrand, H., "Overview: Real Time Protocols for Brower-
based Applications", draft-ietf-rtcweb-overview-05 (work
in progress), December 2012.
[I-D.jesup-rtcweb-data]
Jesup, R., Loreto, S., and M. Tuexen, "RTCWeb Datagram
Connection", draft-jesup-rtcweb-data-01 (work in
progress), October 2011.
Authors' Addresses
Randell Jesup
WorldGate Communications
3800 Horizon Blvd, Suite #103
Trevose, PA 19053-4947
US
Phone: +1-215-354-5166
Email: randell_ietf@jesup.org
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Salvatore Loreto
Ericsson
Hirsalantie 11
Jorvas 02420
FI
Email: Salvatore.Loreto@ericsson.com
Randall R. Stewart
Adara Networks
Chapin, SC 29036
US
Email: randall@lakerest.net
Michael Tuexen
Muenster University of Applied Sciences
Stegerwaldstrasse 39
48565 Steinfurt
DE
Email: tuexen@fh-muenster.de
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