draft-ietf-avtcore-rtp-circuit-breakers-12.txt   draft-ietf-avtcore-rtp-circuit-breakers-13.txt 
AVTCORE Working Group C. Perkins AVTCORE Working Group C. Perkins
Internet-Draft University of Glasgow Internet-Draft University of Glasgow
Updates: 3550 (if approved) V. Singh Updates: 3550 (if approved) V. Singh
Intended status: Standards Track callstats.io Intended status: Standards Track callstats.io
Expires: August 12, 2016 February 9, 2016 Expires: August 13, 2016 February 10, 2016
Multimedia Congestion Control: Circuit Breakers for Unicast RTP Sessions Multimedia Congestion Control: Circuit Breakers for Unicast RTP Sessions
draft-ietf-avtcore-rtp-circuit-breakers-12 draft-ietf-avtcore-rtp-circuit-breakers-13
Abstract Abstract
The Real-time Transport Protocol (RTP) is widely used in telephony, The Real-time Transport Protocol (RTP) is widely used in telephony,
video conferencing, and telepresence applications. Such applications video conferencing, and telepresence applications. Such applications
are often run on best-effort UDP/IP networks. If congestion control are often run on best-effort UDP/IP networks. If congestion control
is not implemented in the applications, then network congestion will is not implemented in the applications, then network congestion will
deteriorate the user's multimedia experience. This acts as a safety deteriorate the user's multimedia experience. This acts as a safety
measure to prevent starvation of network resources denying other measure to prevent starvation of network resources denying other
flows from access to the Internet, such measures are essential for an flows from access to the Internet, such measures are essential for an
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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 August 12, 2016. This Internet-Draft will expire on August 13, 2016.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2016 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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this class of applications in this memo. this class of applications in this memo.
Congestion control relies on monitoring the delivery of a media flow, Congestion control relies on monitoring the delivery of a media flow,
and responding to adapt the transmission of that flow when there are and responding to adapt the transmission of that flow when there are
signs that the network path is congested. Network congestion can be signs that the network path is congested. Network congestion can be
detected in one of three ways: 1) a receiver can infer the onset of detected in one of three ways: 1) a receiver can infer the onset of
congestion by observing an increase in one-way delay caused by queue congestion by observing an increase in one-way delay caused by queue
build-up within the network; 2) if Explicit Congestion Notification build-up within the network; 2) if Explicit Congestion Notification
(ECN) [RFC3168] is supported, the network can signal the presence of (ECN) [RFC3168] is supported, the network can signal the presence of
congestion by marking packets using ECN Congestion Experienced (CE) congestion by marking packets using ECN Congestion Experienced (CE)
marks; or 3) in the extreme case, congestion will cause packet loss marks (this could potentially be augmented by mechanisms such as
that can be detected by observing a gap in the received RTP sequence ConEX [RFC7713], or other future protocol extensions for network
numbers. signalling of congestion); or 3) in the extreme case, congestion will
cause packet loss that can be detected by observing a gap in the
received RTP sequence numbers.
Once the onset of congestion is observed, the receiver has to send Once the onset of congestion is observed, the receiver has to send
feedback to the sender to indicate that the transmission rate needs feedback to the sender to indicate that the transmission rate needs
to be reduced. How the sender reduces the transmission rate is to be reduced. How the sender reduces the transmission rate is
highly dependent on the media codec being used, and is outside the highly dependent on the media codec being used, and is outside the
scope of this memo. scope of this memo.
There are several ways in which a receiver can send feedback to a There are several ways in which a receiver can send feedback to a
media sender within the RTP framework: media sender within the RTP framework:
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[RFC7097] Ott, J., Singh, V., Ed., and I. Curcio, "RTP Control [RFC7097] Ott, J., Singh, V., Ed., and I. Curcio, "RTP Control
Protocol (RTCP) Extended Report (XR) for RLE of Discarded Protocol (RTCP) Extended Report (XR) for RLE of Discarded
Packets", RFC 7097, DOI 10.17487/RFC7097, January 2014, Packets", RFC 7097, DOI 10.17487/RFC7097, January 2014,
<http://www.rfc-editor.org/info/rfc7097>. <http://www.rfc-editor.org/info/rfc7097>.
[RFC7201] Westerlund, M. and C. Perkins, "Options for Securing RTP [RFC7201] Westerlund, M. and C. Perkins, "Options for Securing RTP
Sessions", RFC 7201, DOI 10.17487/RFC7201, April 2014, Sessions", RFC 7201, DOI 10.17487/RFC7201, April 2014,
<http://www.rfc-editor.org/info/rfc7201>. <http://www.rfc-editor.org/info/rfc7201>.
[RFC7713] Mathis, M. and B. Briscoe, "Congestion Exposure (ConEx)
Concepts, Abstract Mechanism, and Requirements", RFC 7713,
DOI 10.17487/RFC7713, December 2015,
<http://www.rfc-editor.org/info/rfc7713>.
[Sarker] Sarker, Z., Singh, V., and C. Perkins, "An Evaluation of [Sarker] Sarker, Z., Singh, V., and C. Perkins, "An Evaluation of
RTP Circuit Breaker Performance on LTE Networks", RTP Circuit Breaker Performance on LTE Networks",
Proceedings of the IEEE Infocom workshop on Communication Proceedings of the IEEE Infocom workshop on Communication
and Networking Techniques for Contemporary Video, 2014, and Networking Techniques for Contemporary Video, 2014,
April 2014. April 2014.
[Singh] Singh, V., McQuistin, S., Ellis, M., and C. Perkins, [Singh] Singh, V., McQuistin, S., Ellis, M., and C. Perkins,
"Circuit Breakers for Multimedia Congestion Control", "Circuit Breakers for Multimedia Congestion Control",
Proceedings of the International Packet Video Proceedings of the International Packet Video
Workshop, 2013, DOI 10.1109/PV.2013.6691439, December Workshop, 2013, DOI 10.1109/PV.2013.6691439, December
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