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<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<table summary="layout" width="66%" border="0" cellpadding="0" cellspacing="0"><tr><td><table summary="layout" width="100%" border="0" cellpadding="2" cellspacing="1">
<tr><td class="header">RMCAT Working Group</td><td class="header">V. Singh</td></tr>
<tr><td class="header">Internet-Draft</td><td class="header">J. Ott</td></tr>
<tr><td class="header">Intended status: Informational</td><td class="header">Aalto University</td></tr>
<tr><td class="header">Expires: April 18, 2013</td><td class="header">October 15, 2012</td></tr>
</table></td></tr></table>
<h1><br />Evaluating Congestion Control for Interactive Real-time Media.<br />draft-singh-rmcat-cc-eval-00.txt</h1>
<h3>Abstract</h3>
<p>The Real-time Transport Protocol (RTP) is used to transmit
media in telephony and video conferencing applications. This
document describes the guidelines to evaluate new congestion
control algorithms for interactive point-to-point real-time
media.
</p>
<h3>Status of this Memo</h3>
<p>
This Internet-Draft is submitted in full
conformance with the provisions of BCP 78 and BCP 79.</p>
<p>
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/.</p>
<p>
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.”</p>
<p>
This Internet-Draft will expire on April 18, 2013.</p>
<h3>Copyright Notice</h3>
<p>
Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved.</p>
<p>
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.</p>
<a name="toc"></a><br /><hr />
<h3>Table of Contents</h3>
<p class="toc">
<a href="#anchor1">1.</a>
Introduction<br />
<a href="#sec-terminology">2.</a>
Terminology<br />
<a href="#cc-metrics">3.</a>
Metrics<br />
<a href="#cc-guidelines">4.</a>
Guidelines<br />
<a href="#anchor2">4.1.</a>
Avoiding Congestion Collapse<br />
<a href="#anchor3">4.2.</a>
Stability<br />
<a href="#anchor4">4.3.</a>
Diverse Environments<br />
<a href="#anchor5">4.4.</a>
Varying Path Characteristics<br />
<a href="#anchor6">4.5.</a>
Reacting to Transient Events or Interruptions<br />
<a href="#anchor7">4.6.</a>
Fairness With Similar Cross-Traffic<br />
<a href="#anchor8">4.7.</a>
Impact on Cross-Traffic<br />
<a href="#anchor9">4.8.</a>
Extensions to RTP/RTCP<br />
<a href="#anchor10">5.</a>
Minimum Requirements for Evaluation<br />
<a href="#cc-scenario">6.</a>
Example Evaluation Scenarios<br />
<a href="#cc-proposal">7.</a>
Status of Proposals<br />
<a href="#anchor11">8.</a>
Security Considerations<br />
<a href="#anchor12">9.</a>
IANA Considerations<br />
<a href="#anchor13">10.</a>
Acknowledgements<br />
<a href="#rfc.references1">11.</a>
References<br />
<a href="#rfc.references1">11.1.</a>
Normative References<br />
<a href="#rfc.references2">11.2.</a>
Informative References<br />
<a href="#rfc.authors">§</a>
Authors' Addresses<br />
</p>
<br clear="all" />
<a name="anchor1"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.1"></a><h3>1.
Introduction</h3>
<p>This memo describes the guidelines to help with evaluating
new congestion control algorithms for interactive
point-to-point real time media. The requirements for the
congestion control algorithm are outlined in <a class='info' href='#I-D.jesup-rtp-congestion-reqs'>[I‑D.jesup‑rtp‑congestion‑reqs]<span> (</span><span class='info'>Jesup, R. and H. Alvestrand, “Congestion Control Requirements For Real Time Media,” March 2012.</span><span>)</span></a>). This document
builds upon previous work at the IETF: <a class='info' href='#RFC5033'>Specifying New Congestion Control
Algorithms<span> (</span><span class='info'>Floyd, S. and M. Allman, “Specifying New Congestion Control Algorithms,” August 2007.</span><span>)</span></a> [RFC5033] and <a class='info' href='#RFC5166'>Metrics for the
Evaluation of Congestion Control Algorithms<span> (</span><span class='info'>Floyd, S., “Metrics for the Evaluation of Congestion Control Mechanisms,” March 2008.</span><span>)</span></a> [RFC5166].
</p>
<p>The guidelines proposed in the document are intended to
prevent a congestion collapse, promote fair capacity usage and
optimize the media flow's throughput, delay, loss and quality.
Furthermore, the proposed algorithms are expected to operate
within the envelope of the circuit breakers defined in <a class='info' href='#I-D.ietf-avtcore-rtp-circuit-breakers'>[I‑D.ietf‑avtcore‑rtp‑circuit‑breakers]<span> (</span><span class='info'>Perkins, C. and V. Singh, “RTP Congestion Control: Circuit Breakers for Unicast Sessions,” October 2012.</span><span>)</span></a>.
</p>
<p>This document only provides broad-level criteria for
evaluating a new congestion control algorithm and the working
group should expect a thorough scientific study to make its
decision. The results of the evaluation are not expected to be
included within the internet-draft but should be cited in the
document.
</p>
<a name="sec-terminology"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.2"></a><h3>2.
Terminology</h3>
<p> The terminology defined in <a class='info' href='#RFC3550'>RTP<span> (</span><span class='info'>Schulzrinne, H., Casner, S., Frederick, R., and V. Jacobson, “RTP: A Transport Protocol for Real-Time Applications,” July 2003.</span><span>)</span></a> [RFC3550], <a class='info' href='#RFC3551'>RTP Profile
for Audio and Video Conferences with Minimal Control<span> (</span><span class='info'>Schulzrinne, H. and S. Casner, “RTP Profile for Audio and Video Conferences with Minimal Control,” July 2003.</span><span>)</span></a> [RFC3551],
<a class='info' href='#RFC3611'>RTCP Extended Report (XR)<span> (</span><span class='info'>Friedman, T., Caceres, R., and A. Clark, “RTP Control Protocol Extended Reports (RTCP XR),” November 2003.</span><span>)</span></a> [RFC3611], <a class='info' href='#RFC4585'>Extended RTP Profile for RTCP-based Feedback
(RTP/AVPF)<span> (</span><span class='info'>Ott, J., Wenger, S., Sato, N., Burmeister, C., and J. Rey, “Extended RTP Profile for Real-time Transport Control Protocol (RTCP)-Based Feedback (RTP/AVPF),” July 2006.</span><span>)</span></a> [RFC4585] and <a class='info' href='#RFC5506'>Support for
Reduced-Size RTCP<span> (</span><span class='info'>Johansson, I. and M. Westerlund, “Support for Reduced-Size Real-Time Transport Control Protocol (RTCP): Opportunities and Consequences,” April 2009.</span><span>)</span></a> [RFC5506] apply.
</p>
<a name="cc-metrics"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.3"></a><h3>3.
Metrics</h3>
<p><a class='info' href='#RFC5166'>[RFC5166]<span> (</span><span class='info'>Floyd, S., “Metrics for the Evaluation of Congestion Control Mechanisms,” March 2008.</span><span>)</span></a> describes the basic metrics for
congestion control. Metrics that are important to interactive
multimedia are:
</p>
<blockquote class="text">
<p></p>
<ul class="text">
<li>Delay
</li>
<li>Throughput
</li>
<li>Minimizing oscillations in encoding rate (stability)
</li>
<li>Reactivity to transient events
</li>
<li>Packet loss and discard rate
</li>
<li>Users' quality of experience
</li>
</ul>
<p>
</p>
<p>[Editor's Note: measurement interval and statistical
measures (min, max, mean, median) are yet to be
specified.]
</p>
</blockquote>
<p> Section 2.1 of <a class='info' href='#RFC5166'>[RFC5166]<span> (</span><span class='info'>Floyd, S., “Metrics for the Evaluation of Congestion Control Mechanisms,” March 2008.</span><span>)</span></a> discusses the
tradeoff between throughput, delay and loss.
</p>
<p> </p>
<blockquote class="text">
<p>(i) Bandwidth Utilization: is the ratio of the encoding
rate to the (available) end-to-end path capacity.
</p>
<ul class="text">
<li>Under-utilization: is the period of time when the
endpoint's encoding rate is lower than the end-to-end
capacity, i.e., the bandwidth utilization is less than
1.
</li>
<li>Overuse: is the period of time when the endpoint's
encoding rate is higher than the end-to-end capacity,
i.e., the bandwidth utilization is greater than 1.
</li>
<li>Stability: is the period of time when the endpoint's
encoding rate is relatively stable, i.e., the bandwidth
utilization is constant.
</li>
</ul>
<p>
</p>
<p>(ii) Packet Loss and Discard Rate.
</p>
<p>
</p>
<p>(iii) Fair Share.
</p>
<p>[Editor's Note: This metric should match the one defined
in the <a class='info' href='#I-D.jesup-rtp-congestion-reqs'>RMCAT
requirements<span> (</span><span class='info'>Jesup, R. and H. Alvestrand, “Congestion Control Requirements For Real Time Media,” March 2012.</span><span>)</span></a> [I‑D.jesup‑rtp‑congestion‑reqs] document.]
</p>
<p>
</p>
<p>(iv) Quality: There are many different types of quality
metrics for audio and video. Audio quality is often
expressed by a MOS ("Mean Opinion Score") and can be
calculated using an objective algorithm <a class='info' href='#I-D.ietf-xrblock-rtcp-xr-qoe'>[I‑D.ietf‑xrblock‑rtcp‑xr‑qoe]<span> (</span><span class='info'>Hunt, G., Clark, A., Wu, W., Schott, R., and G. Zorn, “RTCP XR Blocks for QoE Metric Reporting,” July 2012.</span><span>)</span></a>. Section 4.7 of
<a class='info' href='#RFC3611'>[RFC3611]<span> (</span><span class='info'>Friedman, T., Caceres, R., and A. Clark, “RTP Control Protocol Extended Reports (RTCP XR),” November 2003.</span><span>)</span></a> can also be used for VoIP
metrics. Similarly, there exist several metrics to measure
video quality, for example Peak Signal to Noise Ratio
(PSNR).
</p>
<p>[Editor's Note: Should the algorithm compare average
PSNR of test video sequences or what other video quality
metric can be used?]
</p>
</blockquote><p>
</p>
<a name="cc-guidelines"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.4"></a><h3>4.
Guidelines</h3>
<p>A congestion control algorithm should be tested in
simulation or a testbed environment, and the experiments should
be repeated multiple times to infer statistical significance.
The following guidelines are considered for evaluation:
</p>
<a name="anchor2"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.4.1"></a><h3>4.1.
Avoiding Congestion Collapse</h3>
<p>Does the congestion control propose any changes to (or
diverge from) the circuit breaker conditions defined in <a class='info' href='#I-D.ietf-avtcore-rtp-circuit-breakers'>[I‑D.ietf‑avtcore‑rtp‑circuit‑breakers]<span> (</span><span class='info'>Perkins, C. and V. Singh, “RTP Congestion Control: Circuit Breakers for Unicast Sessions,” October 2012.</span><span>)</span></a>.
</p>
<a name="anchor3"></a><br /><hr />
<table summary="layout" cellpadding="0" cellspacing="2" class="TOCbug" align="right"><tr><td class="TOCbug"><a href="#toc"> TOC </a></td></tr></table>
<a name="rfc.section.4.2"></a><h3>4.2.
Stability</h3>
<p>The congestion control should be assessed for its stability
when the path characteristics do not change over time. Changing
the media encoding rate too often or by too much may adversely
affect the users' quality of experience.
</p>
<a name="anchor4"></a><br /><hr />
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<a name="rfc.section.4.3"></a><h3>4.3.
Diverse Environments</h3>
<p>The congestion control algorithm should be assessed in
heterogeneous environments, containing both wired and wireless
paths. Examples of wireless access technologies are: 802.11x,
HSPA, WCDMA, or GPRS. One of the main challenges of the
wireless environments is the inability to distinguish
congestion induced loss from transmission (bit-error) loss.
Congestion control algorithms may incorrectly identify
transmission loss as congestion loss and reduce the media
encoding rate too much, which may cause oscillatory behavior
and deteriorate the users' quality of experience. Furthermore,
packet loss may induce additional delay in networks with
wireless paths due to link-layer retransmissions.
</p>
<a name="anchor5"></a><br /><hr />
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<a name="rfc.section.4.4"></a><h3>4.4.
Varying Path Characteristics</h3>
<p>The congestion control algorithm should be evaluated for a
range of path characteristics such as, different end-to-end
capacity and latency, varying amount of cross traffic on a
bottle-neck link and a router's queue length. [Editor's Note:
Different types of queueing mechanisms? Random Early Detection
or only DropTail?]. The main motivation for the previous and
current criteria is to determine under which circumstances will
the proposed congestion control algorithm break down and also
determine the operational range of the algorithm.
</p>
<a name="anchor6"></a><br /><hr />
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<a name="rfc.section.4.5"></a><h3>4.5.
Reacting to Transient Events or Interruptions</h3>
<p>The congestion control algorithm should be able to handle
changes in end-to-end capacity and latency. Latency may change
due to route updates, link failures, handovers etc. In mobile
environment the end-to-end capacity may vary due to the
interference, fading, handovers, etc. In wired networks the
end-to-end capacity may vary due to changes in resource
reservation.
</p>
<a name="anchor7"></a><br /><hr />
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<a name="rfc.section.4.6"></a><h3>4.6.
Fairness With Similar Cross-Traffic</h3>
<p>The congestion control algorithm should be evaluated when
competing with other RTP flows using the same congestion
control algorithm. The proposal should highlight the bottleneck
capacity share of each RTP flow.
</p>
<a name="anchor8"></a><br /><hr />
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<a name="rfc.section.4.7"></a><h3>4.7.
Impact on Cross-Traffic</h3>
<p>The congestion control algorithm should be evaluated when
competing with standard TCP. Short TCP flows may be considered
as transient events and the RTP flow may give way to the short
TCP flow to complete quickly. However, long-lived TCP flows may
starve out the RTP flow depending on router queue length. In
the latter case the proposed congestion control for RTP should
be as aggressive as <a class='info' href='#RFC5681'>standard
TCP<span> (</span><span class='info'>Allman, M., Paxson, V., and E. Blanton, “TCP Congestion Control,” September 2009.</span><span>)</span></a> [RFC5681].
</p>
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<a name="rfc.section.4.8"></a><h3>4.8.
Extensions to RTP/RTCP</h3>
<p>The congestion control algorithm should indicate if any
protocol extensions are required to implement it and should
carefully describe the impact of the extension.
</p>
<a name="anchor10"></a><br /><hr />
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<a name="rfc.section.5"></a><h3>5.
Minimum Requirements for Evaluation</h3>
<p>[Editor's Note: If needed, a minimum evaluation criteria can
be based on the above guidelines]
</p>
<a name="cc-scenario"></a><br /><hr />
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<a name="rfc.section.6"></a><h3>6.
Example Evaluation Scenarios</h3>
<p>In the scenarios listed below, all RTP flows are
bi-directional and point-to-point.
</p>
<p></p>
<blockquote class="text">
<p>[S1] RTP flow on a fixed link: This scenario evaluates the
ramp-up to the bottleneck capacity and the stability of the
proposed congestion control algorithm.
</p>
<p>
</p>
<p>[S2] RTP flow on a variable capacity link: This scenario
evaluates the reactivity of the proposed congestion control
algorithm to transient network events due to interference and
handovers in mobile environments. Sample 3G bandwidth traces
are available at <a class='info' href='#3GPP.R1.081955'>[3GPP.R1.081955]<span> (</span><span class='info'>R1-081955, 3GPP., “LTE Link Level Throughput Data for SA4 Evaluation Framework,” 5 2008.</span><span>)</span></a>.
</p>
<p>
</p>
<p>[S3] Fairness to RTP flows running the same congestion
control algorithm: This scenario shows if the proposed
algorithm can share the bottleneck link equitably, irrespective
of number of flows.
</p>
<p>
</p>
<p>[S4] Competing with long-lived TCP flows: In this scenario
the proposed algorithm is expected to be TCP-friendly, i.e., it
should neither starve out the competing TCP flows (causing a
congestion collapse) nor should it be starved out by TCP.
</p>
<p>
</p>
<p>[S5] Competing with short TCP flows: Depending on the level
of statistical multiplexing on the bottleneck link, the
proposed algorithm may behave differently. If there are a few
short TCP flows then the proposed algorithm may observe these
flows as transient events and let them complete quickly.
Alternatively, if there are many short flows then the proposed
algorithm may have to compete with the flows as if they were
long lived TCP flows. [Editor's Note: many and few short TCP
flows may depend on the bottleneck link capacity.]
</p>
</blockquote><p>
</p>
<a name="cc-proposal"></a><br /><hr />
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<a name="rfc.section.7"></a><h3>7.
Status of Proposals</h3>
<p>Congestion control algorithms are expected to be published
as "Experimental" documents until they are shown to be safe to
deploy. An algorithm published as a draft should be
experimented in simulation, or a controlled environment
(testbed) to show its applicability. Every congestion control
algorithm should include a note describing the environments in
which the algorithm is tested and safe to deploy. It is
possible that an algorithm is not recommended for certain
environments or perform sub-optimally for the user.
</p>
<p>[Editor's Note: Should there be a distinction between
"Informational" and "Experimental" drafts for congestion
control algorithms in RMCAT. <a class='info' href='#RFC5033'>[RFC5033]<span> (</span><span class='info'>Floyd, S. and M. Allman, “Specifying New Congestion Control Algorithms,” August 2007.</span><span>)</span></a>
describes Informational proposals as algorithms that are not
safe for deployment but are proposals to experiment with in
simulation/testbeds. While Experimental algorithms are ones
that are deemed safe in some environments but require a more
thorough evaluation (from the community).]
</p>
<a name="anchor11"></a><br /><hr />
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<a name="rfc.section.8"></a><h3>8.
Security Considerations</h3>
<p>Security issues have not been discussed in this memo.
</p>
<a name="anchor12"></a><br /><hr />
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<a name="rfc.section.9"></a><h3>9.
IANA Considerations</h3>
<p>There are no IANA impacts in this memo.
</p>
<a name="anchor13"></a><br /><hr />
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<a name="rfc.section.10"></a><h3>10.
Acknowledgements</h3>
<p> Much of this document is derived from previous work on
congestion control at the IETF.
</p>
<a name="rfc.references"></a><br /><hr />
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<a name="rfc.section.11"></a><h3>11.
References</h3>
<a name="rfc.references1"></a><br /><hr />
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<h3>11.1. Normative References</h3>
<table width="99%" border="0">
<tr><td class="author-text" valign="top"><a name="RFC3550">[RFC3550]</a></td>
<td class="author-text">Schulzrinne, H., Casner, S., Frederick, R., and V. Jacobson, “<a href="http://tools.ietf.org/html/rfc3550">RTP: A Transport Protocol for Real-Time Applications</a>,” STD 64, RFC 3550, July 2003 (<a href="http://www.rfc-editor.org/rfc/rfc3550.txt">TXT</a>, <a href="http://www.rfc-editor.org/rfc/rfc3550.ps">PS</a>, <a href="http://www.rfc-editor.org/rfc/rfc3550.pdf">PDF</a>).</td></tr>
<tr><td class="author-text" valign="top"><a name="RFC3551">[RFC3551]</a></td>
<td class="author-text">Schulzrinne, H. and S. Casner, “<a href="http://tools.ietf.org/html/rfc3551">RTP Profile for Audio and Video Conferences with Minimal Control</a>,” STD 65, RFC 3551, July 2003 (<a href="http://www.rfc-editor.org/rfc/rfc3551.txt">TXT</a>, <a href="http://www.rfc-editor.org/rfc/rfc3551.ps">PS</a>, <a href="http://www.rfc-editor.org/rfc/rfc3551.pdf">PDF</a>).</td></tr>
<tr><td class="author-text" valign="top"><a name="RFC3611">[RFC3611]</a></td>
<td class="author-text">Friedman, T., Caceres, R., and A. Clark, “<a href="http://tools.ietf.org/html/rfc3611">RTP Control Protocol Extended Reports (RTCP XR)</a>,” RFC 3611, November 2003 (<a href="http://www.rfc-editor.org/rfc/rfc3611.txt">TXT</a>).</td></tr>
<tr><td class="author-text" valign="top"><a name="RFC4585">[RFC4585]</a></td>
<td class="author-text">Ott, J., Wenger, S., Sato, N., Burmeister, C., and J. Rey, “<a href="http://tools.ietf.org/html/rfc4585">Extended RTP Profile for Real-time Transport Control Protocol (RTCP)-Based Feedback (RTP/AVPF)</a>,” RFC 4585, July 2006 (<a href="http://www.rfc-editor.org/rfc/rfc4585.txt">TXT</a>).</td></tr>
<tr><td class="author-text" valign="top"><a name="RFC5506">[RFC5506]</a></td>
<td class="author-text">Johansson, I. and M. Westerlund, “<a href="http://tools.ietf.org/html/rfc5506">Support for Reduced-Size Real-Time Transport Control Protocol (RTCP): Opportunities and Consequences</a>,” RFC 5506, April 2009 (<a href="http://www.rfc-editor.org/rfc/rfc5506.txt">TXT</a>).</td></tr>
<tr><td class="author-text" valign="top"><a name="I-D.jesup-rtp-congestion-reqs">[I-D.jesup-rtp-congestion-reqs]</a></td>
<td class="author-text">Jesup, R. and H. Alvestrand, “<a href="http://tools.ietf.org/html/draft-jesup-rtp-congestion-reqs-00">Congestion Control Requirements For Real Time Media</a>,” draft-jesup-rtp-congestion-reqs-00 (work in progress), March 2012 (<a href="http://www.ietf.org/internet-drafts/draft-jesup-rtp-congestion-reqs-00.txt">TXT</a>).</td></tr>
<tr><td class="author-text" valign="top"><a name="I-D.ietf-avtcore-rtp-circuit-breakers">[I-D.ietf-avtcore-rtp-circuit-breakers]</a></td>
<td class="author-text">Perkins, C. and V. Singh, “<a href="http://tools.ietf.org/html/draft-ietf-avtcore-rtp-circuit-breakers-00">RTP Congestion Control: Circuit Breakers for Unicast Sessions</a>,” draft-ietf-avtcore-rtp-circuit-breakers-00 (work in progress), October 2012 (<a href="http://www.ietf.org/internet-drafts/draft-ietf-avtcore-rtp-circuit-breakers-00.txt">TXT</a>).</td></tr>
</table>
<a name="rfc.references2"></a><br /><hr />
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<h3>11.2. Informative References</h3>
<table width="99%" border="0">
<tr><td class="author-text" valign="top"><a name="RFC5033">[RFC5033]</a></td>
<td class="author-text">Floyd, S. and M. Allman, “<a href="http://tools.ietf.org/html/rfc5033">Specifying New Congestion Control Algorithms</a>,” BCP 133, RFC 5033, August 2007 (<a href="http://www.rfc-editor.org/rfc/rfc5033.txt">TXT</a>).</td></tr>
<tr><td class="author-text" valign="top"><a name="RFC5166">[RFC5166]</a></td>
<td class="author-text">Floyd, S., “<a href="http://tools.ietf.org/html/rfc5166">Metrics for the Evaluation of Congestion Control Mechanisms</a>,” RFC 5166, March 2008 (<a href="http://www.rfc-editor.org/rfc/rfc5166.txt">TXT</a>).</td></tr>
<tr><td class="author-text" valign="top"><a name="RFC5681">[RFC5681]</a></td>
<td class="author-text">Allman, M., Paxson, V., and E. Blanton, “<a href="http://tools.ietf.org/html/rfc5681">TCP Congestion Control</a>,” RFC 5681, September 2009 (<a href="http://www.rfc-editor.org/rfc/rfc5681.txt">TXT</a>).</td></tr>
<tr><td class="author-text" valign="top"><a name="I-D.ietf-xrblock-rtcp-xr-qoe">[I-D.ietf-xrblock-rtcp-xr-qoe]</a></td>
<td class="author-text">Hunt, G., Clark, A., Wu, W., Schott, R., and G. Zorn, “<a href="http://tools.ietf.org/html/draft-ietf-xrblock-rtcp-xr-qoe-02">RTCP XR Blocks for QoE Metric Reporting</a>,” draft-ietf-xrblock-rtcp-xr-qoe-02 (work in progress), July 2012 (<a href="http://www.ietf.org/internet-drafts/draft-ietf-xrblock-rtcp-xr-qoe-02.txt">TXT</a>).</td></tr>
<tr><td class="author-text" valign="top"><a name="3GPP.R1.081955">[3GPP.R1.081955]</a></td>
<td class="author-text">R1-081955, 3GPP., “<a href="http://www.3gpp.net/ftp/tsg_ran/WG1_RL1/TSGR1_53/Docs/R1-081955.zip">LTE Link Level Throughput Data for SA4 Evaluation Framework</a>,” 3GPP R1-081955, 5 2008.</td></tr>
</table>
<a name="rfc.authors"></a><br /><hr />
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<h3>Authors' Addresses</h3>
<table width="99%" border="0" cellpadding="0" cellspacing="0">
<tr><td class="author-text"> </td>
<td class="author-text">Varun Singh</td></tr>
<tr><td class="author-text"> </td>
<td class="author-text">Aalto University</td></tr>
<tr><td class="author-text"> </td>
<td class="author-text">School of Electrical Engineering</td></tr>
<tr><td class="author-text"> </td>
<td class="author-text">Otakaari 5 A</td></tr>
<tr><td class="author-text"> </td>
<td class="author-text">Espoo, FIN 02150</td></tr>
<tr><td class="author-text"> </td>
<td class="author-text">Finland</td></tr>
<tr><td class="author" align="right">Email: </td>
<td class="author-text"><a href="mailto:[email protected]">[email protected]</a></td></tr>
<tr cellpadding="3"><td> </td><td> </td></tr>
<tr><td class="author-text"> </td>
<td class="author-text">Joerg Ott</td></tr>
<tr><td class="author-text"> </td>
<td class="author-text">Aalto University</td></tr>
<tr><td class="author-text"> </td>
<td class="author-text">School of Electrical Engineering</td></tr>
<tr><td class="author-text"> </td>
<td class="author-text">Otakaari 5 A</td></tr>
<tr><td class="author-text"> </td>
<td class="author-text">Espoo, FIN 02150</td></tr>
<tr><td class="author-text"> </td>
<td class="author-text">Finland</td></tr>
<tr><td class="author" align="right">Email: </td>
<td class="author-text"><a href="mailto:[email protected]">[email protected]</a></td></tr>
</table>
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