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draft-aboba-avtcore-quic-multiplexing-01.txt
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AVTCORE Working Group B. Aboba
INTERNET-DRAFT Microsoft Corporation
Category: Informational P. Thatcher
Expires: April 29, 2018 Google
C. Perkins
University of Glasgow
29 October 2017
QUIC Multiplexing
draft-aboba-avtcore-quic-multiplexing-01.txt
Abstract
If QUIC is to be used in a peer-to-peer manner, with NAT traversal,
then it is necessary to be able to demultiplex QUIC and STUN flows
running on a single UDP port. This memo discusses options for how to
perform such demultiplexing. It also considers demultiplexing of
QUIC and WebRTC traffic (both media and data) when running on a
single UDP port.
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 April 29, 2018.
Aboba, et. al Informational [Page 1]
INTERNET-DRAFT QUIC Multiplexing 29 October 2017
Copyright Notice
Copyright (c) 2017 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
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
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
2. Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. QUIC Header Changes . . . . . . . . . . . . . . . . . . . 4
2.2. Multiplexing Shim . . . . . . . . . . . . . . . . . . . . 5
2.3. Heuristics . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Security Considerations . . . . . . . . . . . . . . . . . . . 6
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
5. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7
5.1. Informative references . . . . . . . . . . . . . . . . . . 7
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9
Aboba, et. al Informational [Page 2]
INTERNET-DRAFT QUIC Multiplexing 29 October 2017
1. Introduction
QUIC [I-D.ietf-quic-transport] is a new network transport protocol.
While it is initially intended as a replacement for TCP in order to
better support HTTP/2 [RFC7540] it should eventually be useful as a
general purpose transport. HTTP is an asymmetric client-server
protocol, but other uses of QUIC might operate in a peer-to-peer
manner and so will need effective NAT traversal using ICE [RFC5245],
which which makes use of STUN [RFC5389] and TURN [RFC5766] to
discover NAT bindings. This STUN and TURN traffic needs to run on
the same UDP port as the QUIC traffic. Accordingly, if QUIC is to be
used in a peer-to-peer manner, then it needs to be possible to
demultiplex QUIC, STUN, and TURN traffic running on a single UDP
port. This memo discusses how to do this.
In addition, there are a number of ways in which communication
between WebRTC peers may utilize QUIC. One of these is transport of
RTP over QUIC, described in [I-D.rtpfolks-quic-rtp-over-quic].
Another is use of QUIC for data exchange. A Javascript API for use of
QUIC in WebRTC data exchange has been incorporated into the ORTC API
[ORTC], under development within the W3C ORTC Community Group.
In a WebRTC scenario where ICE is utilized for NAT traversal, SRTP
[RFC3711] is keyed using DTLS-SRTP [RFC5764] and QUIC is used for
data exchange, RTP/RTCP [RFC3550], STUN, TURN, DTLS [RFC6347], ZRTP
[RFC6189] and QUIC may all need to be multiplexed over a single ICE
transport.
As noted in [RFC7983] Figure 3, protocol demultiplexing currently
relies upon differentiation based on the first octet, as follows:
+----------------+
| [0..3] -+--> forward to STUN
| |
| [16..19] -+--> forward to ZRTP
| |
packet --> | [20..63] -+--> forward to DTLS
| |
| [64..79] -+--> forward to TURN Channel
| |
| [128..191] -+--> forward to RTP/RTCP
+----------------+
Figure 1: DTLS-SRTP receiver's packet demultiplexing algorithm.
As noted by Colin Perkins and Lars Eggert in [QUIC-Issue] this
creates a potential conflict with the current design of the QUIC
headers described in [I-D.ietf-quic-transport], since the first octet
Aboba, et. al Informational [Page 3]
INTERNET-DRAFT QUIC Multiplexing 29 October 2017
of the QUIC header is either:
+-+-+-+-+-+-+-+-+
|1| Type (7) | Long header packet
+-+-+-+-+-+-+-+-+
which potentially produces values of the first octet in the range
129-134, conflicting with RTP/RTCP, or
+-+-+-+-+-+-+-+-+
|0|C|K| Type (5)| Short header packet
+-+-+-+-+-+-+-+-+
which produces values for the first octet in the ranges 1-3, 33-35,
65-67 or 97-99, potentially conflicting with STUN, DTLS and TURN.
1.1. Terminology
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].
2. Solutions
This section presents potential solutions to the QUIC multiplexing
problem, including changes to the QUIC headers, addition of a
multiplexing octet and use of heuristics.
2.1. QUIC Header Changes
As noted in [QUIC-Issue], one potential solution involves changes to
the QUIC headers, such as setting the top two bits of the first octet
of a QUIC packet to 1. This would imply a reduction in the size of
the type fields:
+-+-+-+-+-+-+-+-+
|1|1|1|Type (5) | Long header packet
+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+
|1|1|0|C|K|Type3| Short header packet
+-+-+-+-+-+-+-+-+
Note: [QUIC-Spin] proposes to add a spin bit to the type octet within
the QUIC header, in order to allow for RTT calculation. This would
leave 4 bits for the type field in the long header packet and 2 bits
for the type field in the short header, which would accommodate the
type field values allocated in [I-D.ietf-quic-transport].
Aboba, et. al Informational [Page 4]
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The advantage to this approach is that it adds no additional
overhead on-the-wire. However it does require a reduction in the
size of the QUIC Type fields and could potentially require
allocation of the following initial octet code points for QUIC:
For the Long header, 225-230 (241-246 when the spin bit is set)
and for the Short header, 193-195 (209-11 with spin bit set),
209-211 (225-227 with spin bit set) and 217-219 (233-235 with the
spin bit set). Utilizing all of these code points for QUIC would
leave limited code points available for future allocations.
2.2. Multiplexing Shim
In this approach, an initial octet not allocated within [RFC7983]
would be prepended to each QUIC packet, allowing QUIC packets to be
differentiated from RTP, RTCP, DTLS, STUN, TURN and ZRTP based on the
first octet alone. As an example, an octet with decimal value 192
could be used:
+-+-+-+-+-+-+-+-+
|1|1|0|0|0|0|0|0|
+-+-+-+-+-+-+-+-+
Advantages of this approach include simplicity and the consumption
of only a single initial octet code point for demultiplexing of
QUIC. The disadvantage is the addition of a single octet of
overhead to every QUIC packet, which could impact performance
where small payloads are exchanged, such as in peer-to-peer
gaming.
2.3. Heuristics
During the QUIC WG interim in Seattle, Martin Thomson suggested the
following heuristics for differentiation of QUIC packets from
RTP/RTCP/DTLS/STUN/TURN/ZRTP:
1. Demultiplex differently during the "QUIC handshake"
and "steady state".
2. During handshake, we only need to worry about the QUIC
Long header, which simplifies the logic.
a. Force all handshake packets to utilize the QUIC Long header.
b. The QUIC Long header (0x1XXXXXXX) (or 0x11XXXXXX with
the spin bit set) does not conflict with STUN (0x000000XX),
DTLS (0x000XXXXX), or TURN Channel (0x01XXXXXX).
c. The QUIC Long header does conflict with RTP/RTCP (0x10XXXXXX),
but those packets typically aren't sent until the QUIC
handshake is completed. Corner case: an application starts
off with audio and video keyed with DTLS-SRTP without QUIC,
then the application wishes to add QUIC data (e.g. the user
Aboba, et. al Informational [Page 5]
INTERNET-DRAFT QUIC Multiplexing 29 October 2017
clicks on the "white-board" icon).
i. Alternative: force the RTP padding bit to 1
using a one-byte pad if there isn't already
padding (pad == 0x01). Then force QUIC to have
a type < 64 (the current max is 8).
ii. Alternative: Disallow QUIC in this case, use SCTP data
exchange instead.
3. During "steady state", we only need to worry about the QUIC
Short header.
a. QUIC doesn't need the Long header after the handshake.
b. The QUIC Short header (0x0XXXXXXX or 0x01XXXXXX with
the spin bit set) does not conflict with RTP/RTCP
(0x10XXXXXX), so we only need to worry about
conflicts with STUN/TURN/DTLS/ZRTP.
c. Disallow simultaneous use of DTLS and QUIC
Short header packets.
i. Alternative: when using DTLS and QUIC at the same
time, only use the QUIC Long header. Not optimal,
but isn't really needed.
d. ICE can be demultiplexed using the magic cookie
and checksum.
i. Alternative: STUN can only conflict with 3
QUIC packet types: Version Negotiation,
Client Initial, and Server Stateless Retry.
Out of those, none should be needed during
the steady state.
e. We shouldn't need to demultiplex QUIC with TURN channel
data or other STUN traffic. What about consent packets?
This approach has the advantage that it requires no changes to
QUIC headers, nor does it add any overhead to QUIC packets.
Disadvantages include additional complexity within the
multiplexing algorithm, the consumption of additional multiplexing
code points, and potential future difficulties in adapting the
algorithm to support changes to the QUIC protocol or additional
protocols to be multiplexed.
3. Security Considerations
The solutions discussed in this document could potentially introduce
some additional security considerations beyond those detailed in
[RFC7983].
Due to the additional logic required, if mis-implemented, heuristics
have the potential to mis-classify packets.
When QUIC is used for only for data exchange, the TLS-within-QUIC
exchange [I-D.ietf-quic-tls] derives keys used solely to protect the
Aboba, et. al Informational [Page 6]
INTERNET-DRAFT QUIC Multiplexing 29 October 2017
QUIC data packets. If properly implemented, this should not affect
the transport of SRTP nor the derivation of SRTP keys via DTLS-SRTP,
but if badly implemented, both transport and key derivation could be
adversely impacted.
4. IANA Considerations
This document does not require actions by IANA.
5. References
5.1. Informative References
[I-D.ietf-quic-tls]
Thomson, M. and S. Turner, "Using Transport Layer Security
(TLS) to Secure QUIC", draft-ietf-quic-tls-07 (work in
progress), October 13, 2017.
[I-D.ietf-quic-transport]
Iyengar, J. and M. Thomson, "QUIC: A UDP-Based Multiplexed
and Secure Transport", draft-ietf-quic-transport-07 (work
in progress), October 13, 2017.
[I-D.rtpfolks-quic-rtp-over-quic]
Ott, J., Even, R., Perkins, C. and V. Singh, "RTP over
QUIC", draft-rtpfolks-quic-rtp-over-quic-01 (work in
progress), September 1, 2017.
[ORTC] Raymond, R., Aboba, B. and J. Uberti, "Object RTC (ORTC)
API for WebRTC", W3C, http://draft.ortc.org/, October 2017.
[QUIC-Issue] Perkins, C., "QUIC header format/demultiplexing",
https://github.com/quicwg/base-drafts/issues/426, March,
2017.
[QUIC-Spin] Huitema, C., "QUIC Latency Spin Bit",
https://github.com/quicwg/base-drafts/issues/609, June
2017.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, DOI
10.17487/RFC2119, March 1997, <http://www.rfc-
editor.org/info/rfc2119>.
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550, July
2003, <http://www.rfc-editor.org/info/rfc3550>.
Aboba, et. al Informational [Page 7]
INTERNET-DRAFT QUIC Multiplexing 29 October 2017
[RFC3711] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K.
Norrman, "The Secure Real-time Transport Protocol (SRTP)",
RFC 3711, DOI 10.17487/RFC3711, March 2004,
<http://www.rfc-editor.org/info/rfc3711>.
[RFC5245] Rosenberg, J., "Interactive Connectivity Establishment
(ICE): A Protocol for Network Address Translator (NAT)
Traversal for Offer/Answer Protocols", RFC 5245, DOI
10.17487/RFC5245, April 2010, <http://www.rfc-
editor.org/info/rfc5245>.
[RFC5389] Rosenberg, J., Mahy, R., Matthews, P., and D. Wing,
"Session Traversal Utilities for NAT (STUN)", RFC 5389, DOI
10.17487/RFC5389, October 2008, <http://www.rfc-
editor.org/info/rfc5389>.
[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, DOI
10.17487/RFC5764, May 2010, <http://www.rfc-
editor.org/info/rfc5764>.
[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, DOI
10.17487/RFC5766, April 2010, <http://www.rfc-
editor.org/info/rfc5766>.
[RFC6189] Zimmermann, P., Johnston, A., Ed., and J. Callas, "ZRTP:
Media Path Key Agreement for Unicast Secure RTP", RFC 6189,
DOI 10.17487/RFC6189, April 2011, <http://www.rfc-
editor.org/info/rfc6189>.
[RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer
Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347,
January 2012, <http://www.rfc-editor.org/info/rfc6347>.
[RFC7540] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext
Transfer Protocol Version 2 (HTTP/2)", RFC 7540, DOI
10.17487/RFC7540, May 2015, <https://www.rfc-
editor.org/info/rfc7540>.
[RFC7983] Petit-Huguenin, M. and G. Salgueiro, "Multiplexing Scheme
Updates for Secure Real-time Transport Protocol (SRTP)
Extension for Datagram Transport Layer Security (DTLS)",
RFC 7983, DOI 10.17487/RFC7983, September 2016,
<https://www.rfc-editor.org/info/rfc7983>.
Aboba, et. al Informational [Page 8]
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Acknowledgments
We would like to thank Martin Thomson, Roni Even and other
participants in the IETF QUIC and AVTCORE working groups for their
discussion of the QUIC multiplexing issue, and their input relating
to potential solutions.
Authors' Addresses
Bernard Aboba
Microsoft Corporation
One Microsoft Way
Redmond, WA 98052
USA
Email: [email protected]
Peter Thatcher
Google
747 6th St S
Kirkland, WA 98033
USA
Email: [email protected]
Colin Perkins
School of Computing Science
University of Glasgow
Glasgow G12 8QQ
United Kingdom
Email: [email protected]
Aboba, et. al Informational [Page 9]