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Versions: (draft-tuexen-tsvwg-sctp-dtls-encaps) 00 01 02 03 04 05 06 07 08 09 RFC 8261

Network Working Group                                          M. Tuexen
Internet-Draft                          Muenster Univ. of Appl. Sciences
Intended status: Standards Track                              R. Stewart
Expires: August 11, 2014                                  Adara Networks
                                                                R. Jesup
                                                WorldGate Communications
                                                               S. Loreto
                                                                Ericsson
                                                        February 7, 2014


                   DTLS Encapsulation of SCTP Packets
                draft-ietf-tsvwg-sctp-dtls-encaps-03.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 document specifies how SCTP can be used on top of
   the Datagram Transport Layer Security (DTLS) protocol.

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
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on August 11, 2014.

Copyright Notice

   Copyright (c) 2014 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect



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   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Encapsulation and Decapsulation Procedure . . . . . . . . . .   3
   4.  DTLS Considerations . . . . . . . . . . . . . . . . . . . . .   3
   5.  SCTP Considerations . . . . . . . . . . . . . . . . . . . . .   3
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   8.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   5
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

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 document specifies how SCTP is used on
   top of the Datagram Transport Layer Security (DTLS) protocol defined
   in [RFC6347].  This encapsulation is used for example within 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.ietf-rtcweb-data-channel].

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.



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   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
   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.

   The DTLS MUST support sending messages larger than the current path
   MTU.  This might result in sending IP level fragmented messages.

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




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   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.

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

   If the dynamic address reconfiguration extension defined in [RFC5061]
   is used, only wildcard addresses MUST be used in ASCONF chunks.

5.4.  SCTP Authentication Extension

   The SCTP authentication extension defined in [RFC4895] can be used
   with DTLS encapsulation, but does not provide any additional benefit.

5.5.  Partial Reliability Extension

   Partial reliability as defined in [RFC3758] can be used in
   combination with DTLS encapsulation.  It is also possible to use
   additional PR-SCTP policies.

5.6.  Stream Reset Extension

   The SCTP stream reset extension defined in [RFC6525] can be used with
   DTLS encapsulation.  It is used to reset streams and add streams
   during the lifetime of the SCTP association.








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5.7.  Interleaving of Large User Messages

   SCTP as defined in [RFC4960] does not support the interleaving of
   large user messages that need to be fragmented and reassembled by the
   SCTP layer.  The protocol extension defined in
   [I-D.ietf-tsvwg-sctp-ndata] overcomes this limitation can can be used
   with DTLS encapsulation.

6.  IANA Considerations

   This document requires no actions from IANA.

7.  Security Considerations

   Security considerations for DTLS are specified in [RFC6347] and for
   SCTP in [RFC4960], [RFC3758], and [RFC6525].  The combination of SCTP
   and DTLS introduces no new security considerations.

8.  Acknowledgments

   The authors wish to thank Gorry Fairhurst for his 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.

   [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.

   [RFC4960]  Stewart, R., "Stream Control Transmission Protocol", RFC
              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
              Layer Security (TLS) and Datagram Transport Layer Security
              (DTLS) Heartbeat Extension", RFC 6520, February 2012.





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9.2.  Informative References

   [RFC3758]  Stewart, R., Ramalho, M., Xie, Q., Tuexen, M., and P.
              Conrad, "Stream Control Transmission Protocol (SCTP)
              Partial Reliability Extension", RFC 3758, May 2004.

   [RFC4895]  Tuexen, M., Stewart, R., Lei, P., and E. Rescorla,
              "Authenticated Chunks for the Stream Control Transmission
              Protocol (SCTP)", RFC 4895, August 2007.

   [RFC5061]  Stewart, R., Xie, Q., Tuexen, M., Maruyama, S., and M.
              Kozuka, "Stream Control Transmission Protocol (SCTP)
              Dynamic Address Reconfiguration", RFC 5061, September
              2007.

   [RFC6525]  Stewart, R., Tuexen, M., and P. Lei, "Stream Control
              Transmission Protocol (SCTP) Stream Reconfiguration", RFC
              6525, February 2012.

   [I-D.ietf-rtcweb-overview]
              Alvestrand, H., "Overview: Real Time Protocols for Brower-
              based Applications", draft-ietf-rtcweb-overview-08 (work
              in progress), September 2013.

   [I-D.ietf-rtcweb-data-channel]
              Jesup, R., Loreto, S., and M. Tuexen, "RTCWeb Data
              Channels", draft-ietf-rtcweb-data-channel-06 (work in
              progress), October 2013.

   [I-D.ietf-tsvwg-sctp-ndata]
              Stewart, R., Tuexen, M., Loreto, S., and R. Seggelmann, "A
              New Data Chunk for Stream Control Transmission Protocol",
              draft-ietf-tsvwg-sctp-ndata-00 (work in progress),
              February 2014.

Authors' Addresses

   Michael Tuexen
   Muenster University of Applied Sciences
   Stegerwaldstrasse 39
   48565 Steinfurt
   DE

   Email: tuexen@fh-muenster.de







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   Randall R. Stewart
   Adara Networks
   Chapin, SC  29036
   US

   Email: randall@lakerest.net


   Randell Jesup
   WorldGate Communications
   3800 Horizon Blvd, Suite #103
   Trevose, PA  19053-4947
   US

   Phone: +1-215-354-5166
   Email: randell_ietf@jesup.org


   Salvatore Loreto
   Ericsson
   Hirsalantie 11
   Jorvas  02420
   FI

   Email: Salvatore.Loreto@ericsson.com


























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