Network Working Group                                           R. Jesup
Internet-Draft                                                   Mozilla
Intended status: Standards Track                               S. Loreto
Expires: December 11, 2014                                      Ericsson
                                                               M. Tuexen
                                        Muenster Univ. of Appl. Sciences
                                                            June 9, 2014

                          WebRTC Data Channels


   The Real-Time Communication in WEB-browsers working group is charged
   to provide protocol support for direct interactive rich communication
   using audio, video, and data between two peers' web-browsers.  This
   document specifies the non-SRTP media data transport aspects of the
   WebRTC framework.  It provides an architectural overview of how the
   Stream Control Transmission Protocol (SCTP) is used in the WebRTC
   context as a generic transport service allowing WEB-browsers to
   exchange generic data from peer to peer.

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

   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 December 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
   ( in effect on the date of

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   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   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.  Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . .   3
     3.1.  Use Cases for Unreliable Data Channels  . . . . . . . . .   3
     3.2.  Use Cases for Reliable Data Channels  . . . . . . . . . .   4
   4.  Requirements  . . . . . . . . . . . . . . . . . . . . . . . .   4
   5.  SCTP over DTLS over UDP Considerations  . . . . . . . . . . .   5
   6.  The Usage of SCTP for Data Channels . . . . . . . . . . . . .   8
     6.1.  SCTP Protocol Considerations  . . . . . . . . . . . . . .   8
     6.2.  Association Setup . . . . . . . . . . . . . . . . . . . .   9
     6.3.  SCTP Streams  . . . . . . . . . . . . . . . . . . . . . .   9
     6.4.  Channel Definition  . . . . . . . . . . . . . . . . . . .   9
     6.5.  Opening a Channel . . . . . . . . . . . . . . . . . . . .  10
     6.6.  Transferring User Data on a Channel . . . . . . . . . . .  10
     6.7.  Closing a Channel . . . . . . . . . . . . . . . . . . . .  11
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  11
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  12
   9.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  12
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  12
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  12
     10.2.  Informative References . . . . . . . . . . . . . . . . .  14
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  14

1.  Introduction

   Non-SRTP media data types in the context of WebRTC are handled by
   using SCTP [RFC4960] encapsulated in DTLS [RFC6347].

                               |   SCTP   |
                               |   DTLS   |
                               | ICE/UDP  |

                       Figure 1: Basic stack diagram

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   The encapsulation of SCTP over DTLS (see
   [I-D.ietf-tsvwg-sctp-dtls-encaps]) over ICE/UDP (see [RFC5245])
   provides a NAT traversal solution together with confidentiality,
   source authentication, and integrity protected transfers.  This data
   transport service operates in parallel to the SRTP media transports,
   and all of them can eventually share a single transport-layer port

   SCTP as specified in [RFC4960] with the partial reliability extension
   defined in [RFC3758] and the additional policies defined in
   [I-D.ietf-tsvwg-sctp-prpolicies] provides multiple streams natively
   with reliable, and the relevant partially-reliable delivery modes for
   user messages.  Using the reconfiguration extension defined in
   [RFC6525] allows to increase the number of streams during the
   lifetime of an SCTP association and to reset individual SCTP streams.
   Using [I-D.ietf-tsvwg-sctp-ndata] allows to interleave large messages
   to avoid the monopolization and adds the support of prioritizing of
   SCTP streams.

   The remainder of this document is organized as follows: Section 3 and
   Section 4 provide use cases and requirements for both unreliable and
   reliable peer to peer data channels; Section 5 discusses SCTP over
   DTLS over UDP; Section 6 provides the specification of how SCTP
   should be used by the WebRTC protocol framework for transporting non-
   SRTP media data between WEB-browsers.

2.  Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in [RFC2119].

3.  Use Cases

   This section defines use cases specific to data channels.  For
   general use cases see [I-D.ietf-rtcweb-use-cases-and-requirements].

3.1.  Use Cases for Unreliable Data Channels

   U-C 1:  A real-time game where position and object state information
           is sent via one or more unreliable data channels.  Note that
           at any time there may be no SRTP media channels, or all SRTP
           media channels may be inactive, and that there may also be
           reliable data channels in use.

   U-C 2:  Providing non-critical information to a user about the reason
           for a state update in a video chat or conference, such as
           mute state.

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3.2.  Use Cases for Reliable Data Channels

   U-C 3:  A real-time game where critical state information needs to be
           transferred, such as control information.  Such a game may
           have no SRTP media channels, or they may be inactive at any
           given time, or may only be added due to in-game actions.

   U-C 4:  Non-realtime file transfers between people chatting.  Note
           that this may involve a large number of files to transfer
           sequentially or in parallel, such as when sharing a folder of
           images or a directory of files.

   U-C 5:  Realtime text chat during an audio and/or video call with an
           individual or with multiple people in a conference.

   U-C 6:  Renegotiation of the configuration of the PeerConnection.

   U-C 7:  Proxy browsing, where a browser uses data channels of a
           PeerConnection to send and receive HTTP/HTTPS requests and
           data, for example to avoid local Internet filtering or

4.  Requirements

   This section lists the requirements for P2P data channels between two

   Req. 1:   Multiple simultaneous data channels MUST be supported.
             Note that there may be 0 or more SRTP media streams in
             parallel with the data channels in the same PeerConnection,
             and the number and state (active/inactive) of these SRTP
             media streams may change at any time.

   Req. 2:   Both reliable and unreliable data channels MUST be

   Req. 3:   Data channels of a PeerConnection MUST be congestion
             controlled; either individually, as a class, or in
             conjunction with the SRTP media streams of the
             PeerConnection, to ensure that data channels don't cause
             congestion problems for these SRTP media streams, and that
             the WebRTC PeerConnection as a whole is fair with competing
             traffic such as TCP.

   Req. 4:   The application SHOULD be able to provide guidance as to
             the relative priority of each data channel relative to each
             other, and relative to the SRTP media streams.  This will
             interact with the congestion control algorithms.

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   Req. 5:   Data channels MUST be secured; allowing for
             confidentiality, integrity and source authentication.  See
             [I-D.ietf-rtcweb-security] and
             [I-D.ietf-rtcweb-security-arch] for detailed info.

   Req. 6:   Data channels MUST provide message fragmentation support
             such that IP-layer fragmentation can be avoided no matter
             how large a message the JavaScript application passes to be
             sent.  It also MUST ensure that large data channel
             transfers don't unduly delay traffic on other data

   Req. 7:   The data channel transport protocol MUST NOT encode local
             IP addresses inside its protocol fields; doing so reveals
             potentially private information, and leads to failure if
             the address is depended upon.

   Req. 8:   The data channel transport protocol SHOULD support
             unbounded-length "messages" (i.e., a virtual socket stream)
             at the application layer, for such things as image-file-
             transfer; Implementations might enforce a reasonable
             message size limit.

   Req. 9:   The data channel transport protocol SHOULD avoid IP
             fragmentation.  It MUST support PMTU (Path MTU) discovery
             and MUST NOT rely on ICMP or ICMPv6 being generated or
             being passed back, especially for PMTU discovery.

   Req. 10:  It MUST be possible to implement the protocol stack in the
             user application space.

5.  SCTP over DTLS over UDP Considerations

   The important features of SCTP in the WebRTC context are:

   o  Usage of a TCP-friendly congestion control.

   o  The congestion control is modifiable for integration with the SRTP
      media stream congestion control.

   o  Support of multiple unidirectional streams, each providing its own
      notion of ordered message delivery.

   o  Support of ordered and out-of-order message delivery.

   o  Supporting arbitrary large user messages by providing
      fragmentation and reassembly.

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   o  Support of PMTU-discovery.

   o  Support of reliable or partially reliable message transport.

   SCTP multihoming will not be used in WebRTC.  The SCTP layer will
   simply act as if it were running on a single-homed host, since that
   is the abstraction that the lower layer (a connection oriented,
   unreliable datagram service) exposes.

   The encapsulation of SCTP over DTLS defined in
   [I-D.ietf-tsvwg-sctp-dtls-encaps] provides confidentiality, source
   authenticated, and integrity protected transfers.  Using DTLS over
   UDP in combination with ICE enables middlebox traversal in IPv4 and
   IPv6 based networks.  SCTP as specified in [RFC4960] MUST be used in
   combination with the extension defined in [RFC3758] and provides the
   following features for transporting non-SRTP media data between

   o  Support of multiple unidirectional streams.

   o  Ordered and unordered delivery of user messages.

   o  Reliable and partial-reliable transport of user messages.

   Each SCTP user message contains a Payload Protocol Identifier (PPID)
   that is passed to SCTP by its upper layer on the sending side and
   provided to its upper layer on the receiving side.  The PPID can be
   used to multiplex/demultiplex multiple upper layers over a single
   SCTP association.  In the WebRTP context, the PPID is used to
   distinguish between UTF-8 encoded user data, binary encoded userdata
   and the Data Channel Establishment Protocol defined in
   [I-D.ietf-rtcweb-data-protocol].  Please note that the PPID is not
   accessible via the Javascript API.

   The encapsulation of SCTP over DTLS, together with the SCTP features
   listed above satisfies all the requirements listed in Section 4.

   The layering of protocols for WebRTC is shown in the following
   Figure 2.

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                                 | DCEP | UTF-8|Binary|
                                 |      | data | data |
                                 |        SCTP        |
                   | STUN | SRTP |        DTLS        |
                   |         ICE                      |
                   | UDP1 | UDP2 | ...                |

                     Figure 2: WebRTC protocol layers

   This stack (especially in contrast to DTLS over SCTP [RFC6083] in
   combination with SCTP over UDP [RFC6951]) has been chosen because it

   o  supports the transmission of arbitrary large user messages.

   o  shares the DTLS connection with the SRTP media channels of the

   o  provides privacy for the SCTP control information.

   Considering the protocol stack of Figure 2 the usage of DTLS over UDP
   is specified in [RFC6347], while the usage of SCTP on top of DTLS is
   specified in [I-D.ietf-tsvwg-sctp-dtls-encaps].  Please note that the
   demultiplexing STUN vs. SRTP vs. DTLS is done as described in
   Section 5.1.2 of [RFC5764] and SCTP is the only payload of DTLS.

   Since DTLS is typically implemented in user-land, the SCTP stack also
   needs to be a user-land stack.

   When using DTLS as the lower layer, only single homed SCTP
   associations are supported, since DTLS does not expose any address
   management to its upper layer.  The ICE/UDP layer can handle IP
   address changes during a session without needing interaction with the
   DTLS and SCTP layers.  However, SCTP SHOULD be notified when an
   address changes has happened.  In this case SCTP SHOULD retest the
   Path MTU and reset the congestion state to the initial state.  In
   case of a window based congestion control like the one specified in
   [RFC4960], this means setting the congestion window and slow start
   threshold to its initial values.

   Incoming ICMP or ICMPv6 messages can't be processed by the SCTP
   layer, since there is no way to identify the corresponding
   association.  Therefore SCTP MUST support performing Path MTU

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   discovery without relying on ICMP or ICMPv6 as specified in [RFC4821]
   using probing messages specified in [RFC4820].  The initial Path MTU
   at the IP layer SHOULD NOT exceed 1200 bytes for IPv4 and 1280 for

   In general, the lower layer interface of an SCTP implementation
   SHOULD be adapted to address the differences between IPv4 and IPv6
   (being connection-less) or DTLS (being connection-oriented).

   When the protocol stack of Figure 2 is used, DTLS protects the
   complete SCTP packet, so it provides confidentiality, integrity and
   source authentication of the complete SCTP packet.

   This SCTP stack and its upper layer MUST support the usage of
   multiple SCTP streams.  A user message can be sent ordered or
   unordered and with partial or full reliability.  The partial
   reliability extension MUST support policies to limit

   o  the transmission and retransmission by time.

   o  the number of retransmissions.

   Limiting the number of retransmissions to zero combined with
   unordered delivery provides a UDP-like service where each user
   message is sent exactly once and delivered in the order received.

   SCTP provides congestion control on a per-association base.  This
   means that all SCTP streams within a single SCTP association share
   the same congestion window.  Traffic not being sent over SCTP is not
   covered by the SCTP congestion control.  Using a congestion control
   different from than the standard one might improve the impact on the
   parallel SRTP media streams.

6.  The Usage of SCTP for Data Channels

6.1.  SCTP Protocol Considerations

   The DTLS encapsulation of SCTP packets as described in
   [I-D.ietf-tsvwg-sctp-dtls-encaps] MUST be used.

   The following SCTP protocol extensions are required:

   o  The stream reset extension defined in [RFC6525] MUST be supported.
      It is used for closing channels.

   o  The dynamic address reconfiguration extension defined in [RFC5061]
      MUST be used to signal the support of the stream reset extension

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      defined in [RFC6525], other features of [RFC5061] are not REQUIRED
      to be implemented.

   o  The partial reliability extension defined in [RFC3758] MUST be
      supported.  In addition to the timed reliability PR-SCTP policy
      defined in [RFC3758], the limited retransmission policy defined in
      [I-D.ietf-tsvwg-sctp-prpolicies] MUST be supported.

   The support for message interleaving as defined in
   [I-D.ietf-tsvwg-sctp-ndata] SHOULD be used.

6.2.  Association Setup

   The SCTP association will be set up when the two endpoints of the
   WebRTC PeerConnection agree on opening it, as negotiated by JSEP
   (typically an exchange of SDP) [I-D.ietf-rtcweb-jsep].  It will use
   the DTLS connection selected via ICE; typically this will be shared
   via BUNDLE or equivalent with DTLS connections used to key the SRTP
   media streams.

   The number of streams negotiated during SCTP association setup SHOULD
   be 65535, which is the maximum number of streams that can negotiated
   during the association setup.

6.3.  SCTP Streams

   SCTP defines a stream as a unidirectional logical channel existing
   within an SCTP association to another SCTP endpoint.  The streams are
   used to provide the notion of in-sequence delivery and for
   multiplexing.  Each user message is sent on a particular stream,
   either ordered or unordered.  Ordering is preserved only for ordered
   messages sent on the same stream.

6.4.  Channel Definition

   The W3C has consensus on defining the application API for WebRTC
   DataChannels to be bidirectional.  They also consider the notions of
   in-sequence, out-of-sequence, reliable and unreliable as properties
   of Channels.  One strong wish is for the application-level API to be
   close to the API for WebSockets, which implies bidirectional streams
   of data and waiting for onopen to fire before sending, a textual
   label used to identify the meaning of the stream, among other things.

   Each data channel also has a priority, which is an 2 byte unsigned
   integer value.  These priorities MUST be interpreted as weighted-
   fair-queuing scheduling priorities per the definition of the
   corresponding stream scheduler supporting interleaving in
   [I-D.ietf-tsvwg-sctp-ndata].  For use in WebRTC, the values used

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   SHOULD be one of 128 ("below normal"), 256 ("normal"), 512 ("high")
   or 1024 ("extra high").

   The realization of a bidirectional Data Channel is a pair of one
   incoming stream and one outgoing SCTP stream having the same stream
   SCTP identifier.

   How stream values are selected is protocol and implementation

6.5.  Opening a Channel

   Data channels can be opened by using negotiation within the SCTP
   association, called in-band negotiation, or out-of-band negotiation.
   Out-of-band negotiation is defined as any method which results in an
   agreement as to the parameters of a channel and the creation thereof.
   The details are out of scope of this document.

   A simple protocol for in-band negotiation is specified in

   When one side wants to open a channel using out-of-band negotiation,
   it picks a stream.  Unless otherwise defined or negotiated, the
   streams are picked based on the DTLS role (the client picks even
   stream identifiers, the server odd stream identifiers).  However, the
   application is responsible for avoiding collisions with existing
   streams.  If it attempts to re-use a stream which is part of an
   existing Channel, the addition SHOULD fail.  In addition to choosing
   a stream, the application SHOULD also determine the options to use
   for sending messages.  The application MUST ensure in an application-
   specific manner that the application at the peer will also know the
   selected stream to be used, and the options for sending data from
   that side.

6.6.  Transferring User Data on a Channel

   All data sent on a Channel in both directions MUST be sent over the
   underlying stream using the reliability defined when the Channel was
   opened unless the options are changed, or per-message options are
   specified by a higher level.

   No more than one message should be put into an SCTP user message.

   The SCTP Payload Protocol Identifiers (PPIDs) are used to signal the
   interpretation of the "Payload data".  For identifying a JavaScript
   string encoded in UTF-8 the PPID "WebRTC String" MUST be used, for
   JavaScript binary data (ArrayBuffer or Blob) the PPID "WebRTC Binary"
   MUST be used (see Section 8).

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   The usage of the PPIDs "WebRTC String Partial" and "WebRTC Binary
   Partial" is deprecated.  They were used for a PPID-based
   fragmentation and reassembly of user messages belonging to reliable
   and ordered data channels.

   If a message with an unsupported PPID is received or some error is
   detected by the receiver (for example, illegal ordering), the
   receiver SHOULD close the corresponding channel.

   The SCTP base protocol specified in [RFC4960] does not support the
   interleaving of user messages.  Therefore sending a large user
   message can monopolize the SCTP association.  To overcome this
   limitation, [I-D.ietf-tsvwg-sctp-ndata] defines an extension to
   support message interleaving, which SHOULD be used.  As long as
   message interleaving is not supported, the sender SHOULD limit the
   maximum message size to 16 KB to avoid monopolization.

   It is recommended that the message size be kept within certain size
   bounds as applications will not be able to support arbitrarily-large
   single messages.  This limit has to be negotiated, for example by
   using [I-D.ietf-mmusic-sctp-sdp].

   The sender SHOULD disable the Nagle algorithm to minimize the

6.7.  Closing a Channel

   Closing of a Data Channel MUST be signaled by resetting the
   corresponding outgoing streams [RFC6525].  This means that if one
   side decides to close the channel, it resets the corresponding
   outgoing stream.  When the peer sees that an incoming stream was
   reset, it also resets its corresponding outgoing stream.  Once this
   is completed, the channel is closed.  Resetting a stream sets the
   Stream Sequence Numbers (SSNs) of the stream back to 'zero' with a
   corresponding notification to the application layer that the reset
   has been performed.  Streams are available to reuse after a reset has
   been performed.

   [RFC6525] also guarantees that all the messages are delivered (or
   abandoned) before resetting the stream.

7.  Security Considerations

   This document does not add any additional considerations to the ones
   given in [I-D.ietf-rtcweb-security] and

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8.  IANA Considerations

   [NOTE to RFC-Editor:

      "RFCXXXX" is to be replaced by the RFC number you assign this


   This document uses four already registered SCTP Payload Protocol
   Identifiers (PPIDs): "DOMString Last", "Binary Data Partial", "Binary
   Data Last", and "DOMString Partial".  [RFC4960] creates the registry
   "SCTP Payload Protocol Identifiers" from which these identifiers were
   assigned.  IANA is requested to update the reference of these four
   assignments to point to this document and change the names of the
   PPIDs.  Therefore these four assignments should be updated to read:

      | Value                              | SCTP PPID | Reference |
      | WebRTC String                      | 51        | [RFCXXXX] |
      | WebRTC Binary Partial (Deprecated) | 52        | [RFCXXXX] |
      | WebRTC Binary                      | 53        | [RFCXXXX] |
      | WebRTC String Partial (Deprecated) | 54        | [RFCXXXX] |

9.  Acknowledgments

   Many thanks for comments, ideas, and text from Harald Alvestrand,
   Adam Bergkvist, Christer Holmberg, Cullen Jennings, Paul Kyzivat,
   Eric Rescorla, Irene Ruengeler, Randall Stewart, Justin Uberti, and
   Magnus Westerlund.

10.  References

10.1.  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.

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   [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.

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

   [RFC5245]  Rosenberg, J., "Interactive Connectivity Establishment
              (ICE): A Protocol for Network Address Translator (NAT)
              Traversal for Offer/Answer Protocols", RFC 5245, April

   [RFC6347]  Rescorla, E. and N. Modadugu, "Datagram Transport Layer
              Security Version 1.2", RFC 6347, January 2012.

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

              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.

              Jesup, R., Loreto, S., and M. Tuexen, "WebRTC Data Channel
              Establishment Protocol", draft-ietf-rtcweb-data-
              protocol-05 (work in progress), May 2014.

              Tuexen, M., Stewart, R., Jesup, R., and S. Loreto, "DTLS
              Encapsulation of SCTP Packets", draft-ietf-tsvwg-sctp-
              dtls-encaps-04 (work in progress), May 2014.

              Rescorla, E., "Security Considerations for WebRTC", draft-
              ietf-rtcweb-security-06 (work in progress), January 2014.

              Rescorla, E., "WebRTC Security Architecture", draft-ietf-
              rtcweb-security-arch-09 (work in progress), February 2014.

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              Uberti, J. and C. Jennings, "Javascript Session
              Establishment Protocol", draft-ietf-rtcweb-jsep-06 (work
              in progress), February 2014.

              Tuexen, M., Seggelmann, R., Stewart, R., and S. Loreto,
              "Additional Policies for the Partial Reliability Extension
              of the Stream Control Transmission Protocol", draft-ietf-
              tsvwg-sctp-prpolicies-03 (work in progress), May 2014.

              Loreto, S. and G. Camarillo, "Stream Control Transmission
              Protocol (SCTP)-Based Media Transport in the Session
              Description Protocol (SDP)", draft-ietf-mmusic-sctp-sdp-06
              (work in progress), February 2014.

10.2.  Informative References

   [RFC5764]  McGrew, D. and E. Rescorla, "Datagram Transport Layer
              Security (DTLS) Extension to Establish Keys for the Secure
              Real-time Transport Protocol (SRTP)", RFC 5764, May 2010.

   [RFC6083]  Tuexen, M., Seggelmann, R., and E. Rescorla, "Datagram
              Transport Layer Security (DTLS) for Stream Control
              Transmission Protocol (SCTP)", RFC 6083, January 2011.

   [RFC6951]  Tuexen, M. and R. Stewart, "UDP Encapsulation of Stream
              Control Transmission Protocol (SCTP) Packets for End-Host
              to End-Host Communication", RFC 6951, May 2013.

              Holmberg, C., Hakansson, S., and G. Eriksson, "Web Real-
              Time Communication Use-cases and Requirements", draft-
              ietf-rtcweb-use-cases-and-requirements-14 (work in
              progress), February 2014.

Authors' Addresses

   Randell Jesup


Jesup, et al.           Expires December 11, 2014              [Page 14]

Internet-Draft            WebRTC Data Channels                 June 2014

   Salvatore Loreto
   Hirsalantie 11
   Jorvas  02420


   Michael Tuexen
   Muenster University of Applied Sciences
   Stegerwaldstrasse 39
   Steinfurt  48565


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