draft-ietf-tsvwg-sctp-dtls-encaps-05.txt   draft-ietf-tsvwg-sctp-dtls-encaps-06.txt 
Network Working Group M. Tuexen Network Working Group M. Tuexen
Internet-Draft Muenster Univ. of Appl. Sciences Internet-Draft Muenster Univ. of Appl. Sciences
Intended status: Standards Track R. Stewart Intended status: Standards Track R. Stewart
Expires: January 5, 2015 Adara Networks Expires: May 15, 2015 Netflix, Inc.
R. Jesup R. Jesup
WorldGate Communications WorldGate Communications
S. Loreto S. Loreto
Ericsson Ericsson
July 4, 2014 November 11, 2014
DTLS Encapsulation of SCTP Packets DTLS Encapsulation of SCTP Packets
draft-ietf-tsvwg-sctp-dtls-encaps-05.txt draft-ietf-tsvwg-sctp-dtls-encaps-06.txt
Abstract Abstract
The Stream Control Transmission Protocol (SCTP) is a transport The Stream Control Transmission Protocol (SCTP) is a transport
protocol originally defined to run on top of the network protocols protocol originally defined to run on top of the network protocols
IPv4 or IPv6. This document specifies how SCTP can be used on top of IPv4 or IPv6. This document specifies how SCTP can be used on top of
the Datagram Transport Layer Security (DTLS) protocol. Using the the Datagram Transport Layer Security (DTLS) protocol. Using the
encapsulation method described in this document, SCTP is agnostic encapsulation method described in this document, SCTP is agnostic
about the protocols being used below DTLS, explicit IP addresses can about the protocols being used below DTLS, explicit IP addresses can
not be used in the SCTP control chunks. As a consequence, the SCTP not be used in the SCTP control chunks. As a consequence, the SCTP
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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 January 5, 2015. This Internet-Draft will expire on May 15, 2015.
Copyright Notice Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the Copyright (c) 2014 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. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. Encapsulation and Decapsulation Procedure . . . . . . . . . . 3 3. Encapsulation and Decapsulation Procedure . . . . . . . . . . 3
4. General Considerations . . . . . . . . . . . . . . . . . . . 3 4. General Considerations . . . . . . . . . . . . . . . . . . . 3
5. DTLS Considerations . . . . . . . . . . . . . . . . . . . . . 3 5. DTLS Considerations . . . . . . . . . . . . . . . . . . . . . 3
6. SCTP Considerations . . . . . . . . . . . . . . . . . . . . . 4 6. SCTP Considerations . . . . . . . . . . . . . . . . . . . . . 4
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
8. Security Considerations . . . . . . . . . . . . . . . . . . . 5 8. Security Considerations . . . . . . . . . . . . . . . . . . . 6
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Overview 1. Overview
The Stream Control Transmission Protocol (SCTP) as defined in The Stream Control Transmission Protocol (SCTP) as defined in
[RFC4960] is a transport protocol running on top of the network [RFC4960] is a transport protocol running on top of the network
protocols IPv4 [RFC0791] or IPv6 [RFC2460]. This document specifies protocols IPv4 [RFC0791] or IPv6 [RFC2460]. This document specifies
how SCTP is used on top of the Datagram Transport Layer Security how SCTP is used on top of the Datagram Transport Layer Security
(DTLS) protocol defined in [RFC4347]. This encapsulation is used for (DTLS) protocol defined in [RFC4347]. This encapsulation is used for
example within the WebRTC protocol suite (see example within the WebRTC protocol suite (see
[I-D.ietf-rtcweb-overview] for an overview) for transporting non-SRTP [I-D.ietf-rtcweb-overview] for an overview) for transporting non-SRTP
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4. General Considerations 4. General Considerations
An implementation of SCTP over DTLS MUST implement and use a path An implementation of SCTP over DTLS MUST implement and use a path
maximum transmission unit (MTU) discovery method that functions maximum transmission unit (MTU) discovery method that functions
without ICMP to provide SCTP/DTLS with an MTU estimate. An without ICMP to provide SCTP/DTLS with an MTU estimate. An
implementation of "Packetization Layer Path MTU Discovery" [RFC4821] implementation of "Packetization Layer Path MTU Discovery" [RFC4821]
either in SCTP or DTLS is RECOMMENDED. either in SCTP or DTLS is RECOMMENDED.
5. DTLS Considerations 5. DTLS Considerations
The DTLS implementation MUST be based on DTLS 1.0 [RFC4347]. The DTLS implementation MUST support DTLS 1.0 [RFC4347] and SHOULD
support the most recently published version of DTLS, which is DTLS
1.2 [RFC6347] as of November 2014. In the absence of a revision to
this document, the latter requirement applies to all future versions
of DTLS when they are published as RFCs. This document will only be
revised if a revision to DTLS or SCTP makes a revision to the
encapsulation necessary.
SCTP performs segmentation and reassembly based on the path MTU. SCTP performs segmentation and reassembly based on the path MTU.
Therefore the DTLS layer MUST NOT use any compression algorithm. Therefore the DTLS layer MUST NOT use any compression algorithm.
The DTLS MUST support sending messages larger than the current path The DTLS MUST support sending messages larger than the current path
MTU. This might result in sending IP level fragmented messages. MTU. This might result in sending IP level fragmented messages.
If path MTU discovery is performed by the DTLS layer, the method If path MTU discovery is performed by the DTLS layer, the method
described in [RFC4821] MUST be used. For probe packets, the described in [RFC4821] MUST be used. For probe packets, the
extension defined in [RFC6520] MUST be used. extension defined in [RFC6520] MUST be used.
If path MTU discovery is performed by the SCTP layer and IPv4 is used If path MTU discovery is performed by the SCTP layer and IPv4 is used
as the network layer protocol, the DTLS implementation SHOULD allow as the network layer protocol, the DTLS implementation SHOULD allow
the DTLS user to enforce that the corresponding IPv4 packet is sent the DTLS user to enforce that the corresponding IPv4 packet is sent
with the Don't Fragment (DF) bit set. If controlling the DF bit is with the Don't Fragment (DF) bit set. If controlling the DF bit is
not possible, for example due to implementation restrictions, a safe not possible, for example due to implementation restrictions, a safe
value for the path MTU has to be used by the SCTP stack. It is value for the path MTU has to be used by the SCTP stack. It is
RECOMMENDED that the save value does not exceed 1200 bytes. RECOMMENDED that the save value does not exceed 1200 bytes. Please
note that [RFC1122] only requires end hosts to be able to reassemble
fragmented IP packets of reassembled size of 576 bytes.
The DTLS implementation SHOULD allow the DTLS user to set the The DTLS implementation SHOULD allow the DTLS user to set the
Differentiated services code point (DSCP) used for IP packets being Differentiated services code point (DSCP) used for IP packets being
sent (see [RFC2474]). This requires the DTLS implementation to pass sent (see [RFC2474]). This requires the DTLS implementation to pass
the value through and the lower layer to allow setting this value. the value through and the lower layer to allow setting this value.
If the lower layer does not support setting the DSCP, then the DTLS If the lower layer does not support setting the DSCP, then the DTLS
user will end up with the default value used by protocol stack. user will end up with the default value used by protocol stack.
Please note that only a single DSCP value can be used for all packets Please note that only a single DSCP value can be used for all packets
belonging to the same SCTP association. belonging to the same SCTP association.
Using explicit congestion notifications (ECN) in SCTP requires the Using explicit congestion notifications (ECN) in SCTP requires the
DTLS layer to pass the ECN bits through and its lower layer to expose DTLS layer to pass the ECN bits through and its lower layer to expose
access to them for sent and received packets (see [RFC3168]). If access to them for sent and received packets (see [RFC3168]). The
this is not possible, for example due to implementation restrictions, implementation of DTLS and its lower layer should provide this
ECN can't be used by SCTP. support. If this is not possible, for example due to implementation
restrictions, ECN can't be used by SCTP.
6. SCTP Considerations 6. SCTP Considerations
This section describes the usage of the base protocol and the This section describes the usage of the base protocol and the
applicability of various SCTP extensions. applicability of various SCTP extensions.
6.1. Base Protocol 6.1. Base Protocol
This document uses SCTP [RFC4960] with the following restrictions, This document uses SCTP [RFC4960] with the following restrictions,
which are required to reflect that the lower layer is DTLS instead of which are required to reflect that the lower layer is DTLS instead of
IPv4 and IPv6 and that SCTP does not deal with the IP addresses or IPv4 and IPv6 and that SCTP does not deal with the IP addresses or
the transport protocol used below DTLS: the transport protocol used below DTLS:
o A DTLS connection MUST be established before an SCTP association o A DTLS connection MUST be established before an SCTP association
can be set up. can be set up.
o Multiple SCTP associations MAY be multiplexed over a single DTLS
connection. The SCTP port numbers are used for multiplexing and
demultiplexing the SCTP associations carried over a single DTLS
connection.
o All SCTP associations are single-homed, because DTLS does not o All SCTP associations are single-homed, because DTLS does not
expose any address management to its upper layer. Therefore it is expose any address management to its upper layer. Therefore it is
RECOMMENDED to set the SCTP parameter path.max.retrans to RECOMMENDED to set the SCTP parameter path.max.retrans to
association.max.retrans. association.max.retrans.
o The INIT and INIT-ACK chunk MUST NOT contain any IPv4 Address or o The INIT and INIT-ACK chunk MUST NOT contain any IPv4 Address or
IPv6 Address parameters. The INIT chunk MUST NOT contain the IPv6 Address parameters. The INIT chunk MUST NOT contain the
Supported Address Types parameter. Supported Address Types parameter.
o The implementation MUST NOT rely on processing ICMP or ICMPv6 o The implementation MUST NOT rely on processing ICMP or ICMPv6
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It should be noted that the inability to process ICMP or ICMPv6 It should be noted that the inability to process ICMP or ICMPv6
messages does not add any security issue. The processing of these messages does not add any security issue. The processing of these
messages for SCTP carried over a connection-less lower layer like IP, messages for SCTP carried over a connection-less lower layer like IP,
IPv6 or UDP is required to protect nodes not supporting SCTP. Since IPv6 or UDP is required to protect nodes not supporting SCTP. Since
DTLS provides a connection-oriented lower layer, this kind of DTLS provides a connection-oriented lower layer, this kind of
protection is not necessary. protection is not necessary.
9. Acknowledgments 9. Acknowledgments
The authors wish to thank Gorry Fairhurst, Eric Rescorla, Joe Touch The authors wish to thank David Black, Gorry Fairhurst, Christer
and Magnus Westerlund for their invaluable comments. Holmberg, Eric Rescorla, Joe Touch and Magnus Westerlund for their
invaluable comments.
10. References 10. References
10.1. Normative References 10.1. Normative References
[RFC1122] Braden, R., "Requirements for Internet Hosts -
Communication Layers", STD 3, RFC 1122, October 1989.
[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, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer [RFC4347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer
Security", RFC 4347, April 2006. Security", RFC 4347, April 2006.
[RFC4820] Tuexen, M., Stewart, R., and P. Lei, "Padding Chunk and [RFC4820] Tuexen, M., Stewart, R., and P. Lei, "Padding Chunk and
Parameter for the Stream Control Transmission Protocol Parameter for the Stream Control Transmission Protocol
(SCTP)", RFC 4820, March 2007. (SCTP)", RFC 4820, March 2007.
[RFC4821] Mathis, M. and J. Heffner, "Packetization Layer Path MTU [RFC4821] Mathis, M. and J. Heffner, "Packetization Layer Path MTU
Discovery", RFC 4821, March 2007. Discovery", RFC 4821, March 2007.
[RFC4960] Stewart, R., "Stream Control Transmission Protocol", RFC [RFC4960] Stewart, R., "Stream Control Transmission Protocol", RFC
4960, September 2007. 4960, 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 [RFC6520] Seggelmann, R., Tuexen, M., and M. Williams, "Transport
Layer Security (TLS) and Datagram Transport Layer Security Layer Security (TLS) and Datagram Transport Layer Security
(DTLS) Heartbeat Extension", RFC 6520, February 2012. (DTLS) Heartbeat Extension", RFC 6520, February 2012.
10.2. Informative References 10.2. Informative References
[RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791, September [RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791, September
1981. 1981.
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
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[RFC6525] Stewart, R., Tuexen, M., and P. Lei, "Stream Control [RFC6525] Stewart, R., Tuexen, M., and P. Lei, "Stream Control
Transmission Protocol (SCTP) Stream Reconfiguration", RFC Transmission Protocol (SCTP) Stream Reconfiguration", RFC
6525, February 2012. 6525, February 2012.
[RFC6951] Tuexen, M. and R. Stewart, "UDP Encapsulation of Stream [RFC6951] Tuexen, M. and R. Stewart, "UDP Encapsulation of Stream
Control Transmission Protocol (SCTP) Packets for End-Host Control Transmission Protocol (SCTP) Packets for End-Host
to End-Host Communication", RFC 6951, May 2013. to End-Host Communication", RFC 6951, May 2013.
[I-D.ietf-rtcweb-overview] [I-D.ietf-rtcweb-overview]
Alvestrand, H., "Overview: Real Time Protocols for Alvestrand, H., "Overview: Real Time Protocols for
Browser-based Applications", draft-ietf-rtcweb-overview-10 Browser-based Applications", draft-ietf-rtcweb-overview-12
(work in progress), June 2014. (work in progress), October 2014.
[I-D.ietf-rtcweb-data-channel] [I-D.ietf-rtcweb-data-channel]
Jesup, R., Loreto, S., and M. Tuexen, "WebRTC Data Jesup, R., Loreto, S., and M. Tuexen, "WebRTC Data
Channels", draft-ietf-rtcweb-data-channel-10 (work in Channels", draft-ietf-rtcweb-data-channel-12 (work in
progress), June 2014. progress), September 2014.
[I-D.ietf-tsvwg-sctp-ndata] [I-D.ietf-tsvwg-sctp-ndata]
Stewart, R., Tuexen, M., Loreto, S., and R. Seggelmann, "A Stewart, R., Tuexen, M., Loreto, S., and R. Seggelmann,
New Data Chunk for Stream Control Transmission Protocol", "Stream Schedulers and a New Data Chunk for the Stream
draft-ietf-tsvwg-sctp-ndata-00 (work in progress), Control Transmission Protocol", draft-ietf-tsvwg-sctp-
February 2014. ndata-01 (work in progress), July 2014.
Authors' Addresses Authors' Addresses
Michael Tuexen Michael Tuexen
Muenster University of Applied Sciences Muenster University of Applied Sciences
Stegerwaldstrasse 39 Stegerwaldstrasse 39
48565 Steinfurt 48565 Steinfurt
DE DE
Email: tuexen@fh-muenster.de Email: tuexen@fh-muenster.de
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Authors' Addresses Authors' Addresses
Michael Tuexen Michael Tuexen
Muenster University of Applied Sciences Muenster University of Applied Sciences
Stegerwaldstrasse 39 Stegerwaldstrasse 39
48565 Steinfurt 48565 Steinfurt
DE DE
Email: tuexen@fh-muenster.de Email: tuexen@fh-muenster.de
Randall R. Stewart Randall R. Stewart
Adara Networks Netflix, Inc.
Chapin, SC 29036 Chapin, SC 29036
US US
Email: randall@lakerest.net Email: randall@lakerest.net
Randell Jesup Randell Jesup
WorldGate Communications WorldGate Communications
3800 Horizon Blvd, Suite #103 3800 Horizon Blvd, Suite #103
Trevose, PA 19053-4947 Trevose, PA 19053-4947
US US
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