Network Working Group H. Alvestrand
Internet-Draft Google
Intended status: Standards Track September 3, 2013
Expires: March 7, 2014
Transports for RTCWEB
draft-ietf-rtcweb-transports-01
Abstract
This document describes the data transport protocols used by RTCWEB,
including the protocols used for interaction with intermediate boxes
such as firewalls, relays and NAT boxes.
Requirements Language
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 RFC 2119 [RFC2119].
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
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Internet-Drafts are draft documents valid for a maximum of six months
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This Internet-Draft will expire on March 7, 2014.
Copyright Notice
Copyright (c) 2013 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
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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 . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Transport and Middlebox specification . . . . . . . . . . . . . 3
2.1. System-provided interfaces . . . . . . . . . . . . . . . . 3
2.2. Middle box related functions . . . . . . . . . . . . . . . 4
2.3. Transport protocols implemented . . . . . . . . . . . . . . 4
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
4. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5
6.1. Normative References . . . . . . . . . . . . . . . . . . . 5
6.2. Informative References . . . . . . . . . . . . . . . . . . 7
Appendix A. Change log . . . . . . . . . . . . . . . . . . . . . . 7
A.1. Changes from -00 to -01 . . . . . . . . . . . . . . . . . . 7
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 7
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1. Introduction
The IETF RTCWEB effort, part of the WebRTC effort carried out in
cooperation between the IETF and the W3C, is aimed at specifying a
protocol suite that is useful for real time multimedia exchange
between browsers.
The overall effort is described in the RTCWEB overview document,
[I-D.ietf-rtcweb-overview]. This document focuses on the data
transport protocos that are used by conforming implementations.
This protocol suite is designed for WebRTC, and intends to satisfy
the security considerations described in the WebRTC security
documents, [I-D.ietf-rtcweb-security] and
[I-D.ietf-rtcweb-security-arch].
2. Transport and Middlebox specification
2.1. System-provided interfaces
The protocol specifications used here assume that the following
protocols are available to the implementations of the RTCWEB
protocols:
o UDP. This is the protocol assumed by most protocol elements
described.
o TCP. This is used for HTTP/WebSockets, as well as for TURN/SSL
and ICE-TCP.
For both protocols, this specification assumes the ability to set the
DSCP code point of the sockets opened on a per-packet basis, in order
to achieve the prioritizations described in [I-D.ietf-rtcweb-qos].
It does not assume that the DSCP codepoints will be honored, and does
assume that they may be zeroed or changed, since this is a local
configuration issue.
If DSCP code points can only be set on a per-socket basis, not per-
packet, one loses the ability to have the network discriminate
reliably between classes of traffic sent over the same transport, but
this does not prevent communication.
This specification does not assume that the implementation will have
access to ICMP or raw IP.
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2.2. Middle box related functions
The primary mechanism to deal with middle boxes is ICE, which is an
appropriate way to deal with NAT boxes and firewalls that accept
traffic from the inside, but only from the outside if it's in
response to inside traffic (simple stateful firewalls).
In order to deal with situations where both parties are behind NATs
which perform endpoint-dependent mapping (as defined in [RFC5128]
section 2.4), TURN [RFC5766] MUST be supported.
In order to deal with firewalls that block all UDP traffic, TURN
using TCP between the client and the server MUST be supported, and
TURN using TLS between the client and the server MUST be supported.
ICE TCP candidates [RFC6062] MAY be supported; this may allow
applications to achieve peer-to-peer communication across UDP-
blocking firewalls, but this also requires use of the SRTP/AVPF/TCP
profile of RTP.
The following specifications MUST be supported:
o ICE [RFC5245]
o TURN, including TURN over TCP[RFC5766].
TURN over TLS over TCP MAY be supported. (QUESTION: SHOULD? MUST?)
For referring to STUN and TURN servers, this specification depends on
the STUN URI, [I-D.nandakumar-rtcweb-stun-uri].
Further discussion of the interaction of RTCWEB with firewalls is
contained in [I-D.hutton-rtcweb-nat-firewall-considerations]. This
document makes no requirements on interacting with HTTP proxies or
HTTP proxy configuration methods.
2.3. Transport protocols implemented
For data transport over the RTCWEB data channel
[I-D.ietf-rtcweb-data-channel], RTCWEB implementations support SCTP
over DTLS over ICE. This is specified in
[I-D.ietf-tsvwg-sctp-dtls-encaps]. Negotiation of this transport in
SCTP is defined in [I-D.ietf-mmusic-sctp-sdp].
The setup protocol for RTCWEB data channels is described in
[I-D.jesup-rtcweb-data-protocol].
For transport of media, secure RTP is used. The details of the
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profile of RTP used are described in "RTP Usage"
[I-D.ietf-rtcweb-rtp-usage].
RTCWEB implementations MUST support multiplexing of DTLS and RTP over
the same port pair, as described in the DTLS_SRTP specification
[RFC5764], section 5.1.2. Further separation of the DTLS traffic
into SCTP and "other" is described in <need reference>.
3. IANA Considerations
This document makes no request of IANA.
Note to RFC Editor: this section may be removed on publication as an
RFC.
4. Security Considerations
Security considerations are enumerated in [I-D.ietf-rtcweb-security].
5. Acknowledgements
This document is based on earlier versions embedded in
[I-D.ietf-rtcweb-overview], which were the results of contributions
from many RTCWEB WG members.
6. References
6.1. Normative References
[I-D.ietf-mmusic-sctp-sdp]
Loreto, S. and G. Camarillo, "Stream Control Transmission
Protocol (SCTP)-Based Media Transport in the Session
Description Protocol (SDP)", draft-ietf-mmusic-sctp-sdp-04
(work in progress), June 2013.
[I-D.ietf-rtcweb-data-channel]
Jesup, R., Loreto, S., and M. Tuexen, "RTCWeb Data
Channels", draft-ietf-rtcweb-data-channel-05 (work in
progress), July 2013.
[I-D.ietf-rtcweb-qos]
Dhesikan, S., Druta, D., Jones, P., and J. Polk, "DSCP and
other packet markings for RTCWeb QoS",
draft-ietf-rtcweb-qos-00 (work in progress), October 2012.
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[I-D.ietf-rtcweb-rtp-usage]
Perkins, C., Westerlund, M., and J. Ott, "Web Real-Time
Communication (WebRTC): Media Transport and Use of RTP",
draft-ietf-rtcweb-rtp-usage-07 (work in progress),
July 2013.
[I-D.ietf-rtcweb-security]
Rescorla, E., "Security Considerations for WebRTC",
draft-ietf-rtcweb-security-05 (work in progress),
July 2013.
[I-D.ietf-rtcweb-security-arch]
Rescorla, E., "WebRTC Security Architecture",
draft-ietf-rtcweb-security-arch-07 (work in progress),
July 2013.
[I-D.ietf-tsvwg-sctp-dtls-encaps]
Jesup, R., Loreto, S., Stewart, R., and M. Tuexen, "DTLS
Encapsulation of SCTP Packets",
draft-ietf-tsvwg-sctp-dtls-encaps-01 (work in progress),
July 2013.
[I-D.nandakumar-rtcweb-stun-uri]
Nandakumar, S., Salgueiro, G., Jones, P., and M. Petit-
Huguenin, "URI Scheme for Session Traversal Utilities for
NAT (STUN) Protocol", draft-nandakumar-rtcweb-stun-uri-05
(work in progress), July 2013.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5245] Rosenberg, J., "Interactive Connectivity Establishment
(ICE): A Protocol for Network Address Translator (NAT)
Traversal for Offer/Answer Protocols", RFC 5245,
April 2010.
[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.
[RFC5766] Mahy, R., Matthews, P., and J. Rosenberg, "Traversal Using
Relays around NAT (TURN): Relay Extensions to Session
Traversal Utilities for NAT (STUN)", RFC 5766, April 2010.
[RFC6062] Perreault, S. and J. Rosenberg, "Traversal Using Relays
around NAT (TURN) Extensions for TCP Allocations",
RFC 6062, November 2010.
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6.2. Informative References
[I-D.hutton-rtcweb-nat-firewall-considerations]
Stach, T., Hutton, A., and J. Uberti, "RTCWEB
Considerations for NATs, Firewalls and HTTP proxies",
draft-hutton-rtcweb-nat-firewall-considerations-01 (work
in progress), June 2013.
[I-D.ietf-rtcweb-overview]
Alvestrand, H., "Overview: Real Time Protocols for Brower-
based Applications", draft-ietf-rtcweb-overview-07 (work
in progress), August 2013.
[I-D.jesup-rtcweb-data-protocol]
Jesup, R., Loreto, S., and M. Tuexen, "WebRTC Data Channel
Protocol", draft-jesup-rtcweb-data-protocol-04 (work in
progress), February 2013.
[RFC5128] Srisuresh, P., Ford, B., and D. Kegel, "State of Peer-to-
Peer (P2P) Communication across Network Address
Translators (NATs)", RFC 5128, March 2008.
Appendix A. Change log
A.1. Changes from -00 to -01
o Clarified DSCP requirements, with reference to -qos-
o Clarified "symmetric NAT" -> "NATs which perform endpoint-
dependent mapping"
o Made support of TURN over TCP mandatory
o Made support of TURN over TLS a MAY, and added open question
o Added an informative reference to -firewalls-
o Called out that we don't make requirements on HTTP proxy
interaction (yet)
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Author's Address
Harald Alvestrand
Google
Email: harald@alvestrand.no
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