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<!DOCTYPE html>
<html lang="en" class="RFC">
<head>
<meta charset="utf-8">
<meta content="Common,Latin" name="scripts">
<meta content="initial-scale=1.0" name="viewport">
<title>RFC 8867: Test Cases for Evaluating Congestion Control for Interactive Real-Time Media</title>
<meta content="Zaheduzzaman Sarker" name="author">
<meta content="Varun Singh" name="author">
<meta content="Xiaoqing Zhu" name="author">
<meta content="Michael A. Ramalho" name="author">
<meta content="
       The Real-time Transport Protocol (RTP) is used to transmit media in
      multimedia telephony applications. These applications are typically
      required to implement congestion control. This document describes the
      test cases to be used in the performance evaluation of such congestion
      control algorithms in a controlled environment. 
    " name="description">
<meta content="xml2rfc 3.5.0" name="generator">
<meta content="Multimedia" name="keyword">
<meta content="Test cases" name="keyword">
<meta content="Congestion Control" name="keyword">
<meta content="8867" name="rfc.number">
<!-- Generator version information:
  xml2rfc 3.5.0
    Python 3.6.10
    appdirs 1.4.4
    ConfigArgParse 1.2.3
    google-i18n-address 2.3.5
    html5lib 1.0.1
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    PyYAML 5.3.1
    requests 2.22.0
    setuptools 40.6.2
    six 1.14.0
    WeasyPrint 51
-->
<link href="rfc8867.xml" rel="alternate" type="application/rfc+xml">
<link href="#copyright" rel="license">
<style type="text/css">/*

  NOTE: Changes at the bottom of this file overrides some earlier settings.

  Once the style has stabilized and has been adopted as an official RFC style,
  this can be consolidated so that style settings occur only in one place, but
  for now the contents of this file consists first of the initial CSS work as
  provided to the RFC Formatter (xml2rfc) work, followed by itemized and
  commented changes found necssary during the development of the v3
  formatters.

*/

/* fonts */
@import url('https://fonts.googleapis.com/css?family=Noto+Sans'); /* Sans-serif */
@import url('https://fonts.googleapis.com/css?family=Noto+Serif'); /* Serif (print) */
@import url('https://fonts.googleapis.com/css?family=Roboto+Mono'); /* Monospace */

@viewport {
  zoom: 1.0;
  width: extend-to-zoom;
}
@-ms-viewport {
  width: extend-to-zoom;
  zoom: 1.0;
}
/* general and mobile first */
html {
}
body {
  max-width: 90%;
  margin: 1.5em auto;
  color: #222;
  background-color: #fff;
  font-size: 14px;
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  scroll-behavior: smooth;
}
.ears {
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}

/* headings */
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  font-weight: bold;
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svg {
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ul.compact, .ulCompact,
ol.compact, .olCompact {
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/* definition lists */
dl {
}
dl > dt {
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/* 
dl.nohang > dt {
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}
*/
dl > dd {
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dl.compact > dd, .dlCompact > dd {
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dl > dd > dl {
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/* links */
a {
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a[href] {
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}
a[href]:hover {
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figcaption a[href],
a[href].selfRef {
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/* XXX probably not this:
a.selfRef:hover {
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/* Figures */
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pre {
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blockquote {
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cite {
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/* tables */
table {
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th, td {
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th {
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table p {
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/* pilcrow */
a.pilcrow {
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.bcp14 {
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.role {
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#identifiers dt {
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#identifiers dd {
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#identifiers .authors .author {
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#identifiers .authors .org {
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/* The prepared/rendered info at the very bottom of the page */
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}
.docInfo .prepared {
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}
.docInfo .prepared {
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}

/* table of contents */
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nav.toc ul {
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}
nav.toc li {
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  padding-left: 1.2em;
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}
/* references */
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}
.references dd {
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}

.refInstance {
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}

.references .ascii {
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}

/* index */
.index ul {
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}
.index ul ul {
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}
.index li {
  margin: 0;
  text-indent: -2em;
  padding-left: 2em;
  padding-bottom: 5px;
}
.indexIndex {
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}
.index a {
  font-weight: 700;
}
/* make the index two-column on all but the smallest screens */
@media (min-width: 600px) {
  .index ul {
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    -moz-column-gap: 20px;
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  .index ul ul {
    -moz-column-count: 1;
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}

/* authors */
address.vcard {
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address.vcard .nameRole {
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}
address.vcard .label {
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address.vcard .type {
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.alternative-contact {
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}
hr.addr {
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}

/* temporary notes */
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  right: 0.2em;
  padding: 0.2em;
  content: "The RFC Editor will remove this note";
  color: #9e2a00; /* Arlen: WCAG 2019 */
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}
.rfcEditorRemove {
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  background-color: #ffd; /* Arlen: WCAG 2019 */
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}
.cref {
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}
.crefSource {
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}
/* alternative layout for smaller screens */
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  }
  #title {
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  }
  h1 {
    font-size: 24px;
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  h2 {
    font-size: 20px;
    margin-top: -18px;  /* provide offset for in-page anchors */
    padding-top: 38px;
  }
  #identifiers dd {
    max-width: 60%;
  }
  #toc {
    position: fixed;
    z-index: 2;
    top: 0;
    right: 0;
    padding: 0;
    margin: 0;
    background-color: inherit;
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  #toc h2 {
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    padding: 4px 0 4px 6px;
    padding-right: 1em;
    min-width: 190px;
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    text-align: right;
    background-color: #444;
    color: white;
    cursor: pointer;
  }
  #toc h2::before { /* css hamburger */
    float: right;
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    width: 1em;
    height: 1px;
    left: -164px;
    margin: 6px 0 0 0;
    background: white none repeat scroll 0 0;
    box-shadow: 0 4px 0 0 white, 0 8px 0 0 white;
    content: "";
  }
  #toc nav {
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    border-left: 1px solid #ddd;
  }
}

/* alternative layout for wide screens */
@media screen and (min-width: 1024px) {
  body {
    max-width: 724px;
    margin: 42px auto;
    padding-left: 1.5em;
    padding-right: 29em;
  }
  #toc {
    position: fixed;
    top: 42px;
    right: 42px;
    width: 25%;
    margin: 0;
    padding: 0 1em;
    z-index: 1;
  }
  #toc h2 {
    border-top: none;
    border-bottom: 1px solid #ddd;
    font-size: 1em;
    font-weight: normal;
    margin: 0;
    padding: 0.25em 1em 1em 0;
  }
  #toc nav {
    display: block;
    height: calc(90vh - 84px);
    bottom: 0;
    padding: 0.5em 0 0;
    overflow: auto;
  }
  img { /* future proofing */
    max-width: 100%;
    height: auto;
  }
}

/* pagination */
@media print {
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    width: 100%;
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    widows: 3;
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  #toc, #n-introduction {
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  #toc {
    border-top: none;
    padding-top: 0;
  }
  figure, pre {
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  figure {
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  h1, h2, h3, h4, h5, h6 {
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  }
  h2+*, h3+*, h4+*, h5+*, h6+* {
    page-break-before: avoid;
  }
  pre {
    white-space: pre-wrap;
    word-wrap: break-word;
    font-size: 10pt;
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  table {
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  td {
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}

/* This is commented out here, as the string-set: doesn't
   pass W3C validation currently */
/*
.ears thead .left {
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}

.ears thead .center {
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.ears tfoot .center {
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.ears tfoot .right {
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*/

@page :first {
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    content: normal;
    border: none;
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}

@page {
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  margin-bottom: 45mm;
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     the content depends on the document */
  /*
  @top-left {
    content: 'Internet-Draft';
    vertical-align: bottom;
    border-bottom: solid 1px #ccc;
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  @top-left {
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    vertical-align: bottom;
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}

/* Changes introduced to fix issues found during implementation */
/* Make sure links are clickable even if overlapped by following H* */
a {
  z-index: 2;
}
/* Separate body from document info even without intervening H1 */
section {
  clear: both;
}


/* Top align author divs, to avoid names without organization dropping level with org names */
.author {
  vertical-align: top;
}

/* Leave room in document info to show Internet-Draft on one line */
#identifiers dt {
  width: 8em;
}

/* Don't waste quite as much whitespace between label and value in doc info */
#identifiers dd {
  margin-left: 1em;
}

/* Give floating toc a background color (needed when it's a div inside section */
#toc {
  background-color: white;
}

/* Make the collapsed ToC header render white on gray also when it's a link */
@media screen and (max-width: 1023px) {
  #toc h2 a,
  #toc h2 a:link,
  #toc h2 a:focus,
  #toc h2 a:hover,
  #toc a.toplink,
  #toc a.toplink:hover {
    color: white;
    background-color: #444;
    text-decoration: none;
  }
}

/* Give the bottom of the ToC some whitespace */
@media screen and (min-width: 1024px) {
  #toc {
    padding: 0 0 1em 1em;
  }
}

/* Style section numbers with more space between number and title */
.section-number {
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}

/* prevent monospace from becoming overly large */
tt, code, pre, code {
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}

/* Fix the height/width aspect for ascii art*/
pre.sourcecode,
.art-text pre {
  line-height: 1.12;
}


/* Add styling for a link in the ToC that points to the top of the document */
a.toplink {
  float: right;
  margin-right: 0.5em;
}

/* Fix the dl styling to match the RFC 7992 attributes */
dl > dt,
dl.dlParallel > dt {
  float: left;
  margin-right: 1em;
}
dl.dlNewline > dt {
  float: none;
}

/* Provide styling for table cell text alignment */
table td.text-left,
table th.text-left {
  text-align: left;
}
table td.text-center,
table th.text-center {
  text-align: center;
}
table td.text-right,
table th.text-right {
  text-align: right;
}

/* Make the alternative author contact informatio look less like just another
   author, and group it closer with the primary author contact information */
.alternative-contact {
  margin: 0.5em 0 0.25em 0;
}
address .non-ascii {
  margin: 0 0 0 2em;
}

/* With it being possible to set tables with alignment
  left, center, and right, { width: 100%; } does not make sense */
table {
  width: auto;
}

/* Avoid reference text that sits in a block with very wide left margin,
   because of a long floating dt label.*/
.references dd {
  overflow: visible;
}

/* Control caption placement */
caption {
  caption-side: bottom;
}

/* Limit the width of the author address vcard, so names in right-to-left
   script don't end up on the other side of the page. */

address.vcard {
  max-width: 30em;
  margin-right: auto;
}

/* For address alignment dependent on LTR or RTL scripts */
address div.left {
  text-align: left;
}
address div.right {
  text-align: right;
}

/* Provide table alignment support.  We can't use the alignX classes above
   since they do unwanted things with caption and other styling. */
table.right {
 margin-left: auto;
 margin-right: 0;
}
table.center {
 margin-left: auto;
 margin-right: auto;
}
table.left {
 margin-left: 0;
 margin-right: auto;
}

/* Give the table caption label the same styling as the figcaption */
caption a[href] {
  color: #222;
}

@media print {
  .toplink {
    display: none;
  }

  /* avoid overwriting the top border line with the ToC header */
  #toc {
    padding-top: 1px;
  }

  /* Avoid page breaks inside dl and author address entries */
  .vcard {
    page-break-inside: avoid;
  }

}
/* Tweak the bcp14 keyword presentation */
.bcp14 {
  font-variant: small-caps;
  font-weight: bold;
  font-size: 0.9em;
}
/* Tweak the invisible space above H* in order not to overlay links in text above */
 h2 {
  margin-top: -18px;  /* provide offset for in-page anchors */
  padding-top: 31px;
 }
 h3 {
  margin-top: -18px;  /* provide offset for in-page anchors */
  padding-top: 24px;
 }
 h4 {
  margin-top: -18px;  /* provide offset for in-page anchors */
  padding-top: 24px;
 }
/* Float artwork pilcrow to the right */
@media screen {
  .artwork a.pilcrow {
    display: block;
    line-height: 0.7;
    margin-top: 0.15em;
  }
}
/* Make pilcrows on dd visible */
@media screen {
  dd:hover > a.pilcrow {
    visibility: visible;
  }
}
/* Make the placement of figcaption match that of a table's caption
   by removing the figure's added bottom margin */
.alignLeft.art-text,
.alignCenter.art-text,
.alignRight.art-text {
   margin-bottom: 0;
}
.alignLeft,
.alignCenter,
.alignRight {
  margin: 1em 0 0 0;
}
/* In print, the pilcrow won't show on hover, so prevent it from taking up space,
   possibly even requiring a new line */
@media print {
  a.pilcrow {
    display: none;
  }
}
/* Styling for the external metadata */
div#external-metadata {
  background-color: #eee;
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<link href="https://dx.doi.org/10.17487/rfc8867" rel="alternate">
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<table class="ears">
<thead><tr>
<td class="left">RFC 8867</td>
<td class="center">Test Scenarios for RMCAT</td>
<td class="right">January 2021</td>
</tr></thead>
<tfoot><tr>
<td class="left">Sarker, et al.</td>
<td class="center">Informational</td>
<td class="right">[Page]</td>
</tr></tfoot>
</table>
<div id="external-metadata" class="document-information"></div>
<div id="internal-metadata" class="document-information">
<dl id="identifiers">
<dt class="label-stream">Stream:</dt>
<dd class="stream">Internet Engineering Task Force (IETF)</dd>
<dt class="label-rfc">RFC:</dt>
<dd class="rfc"><a href="https://www.rfc-editor.org/rfc/rfc8867" class="eref">8867</a></dd>
<dt class="label-category">Category:</dt>
<dd class="category">Informational</dd>
<dt class="label-published">Published:</dt>
<dd class="published">
<time datetime="2021-01" class="published">January 2021</time>
    </dd>
<dt class="label-issn">ISSN:</dt>
<dd class="issn">2070-1721</dd>
<dt class="label-authors">Authors:</dt>
<dd class="authors">
<div class="author">
      <div class="author-name">Z. Sarker</div>
<div class="org">Ericsson AB</div>
</div>
<div class="author">
      <div class="author-name">V. Singh</div>
<div class="org">callstats.io</div>
</div>
<div class="author">
      <div class="author-name">X. Zhu</div>
<div class="org">Cisco Systems</div>
</div>
<div class="author">
      <div class="author-name">M. Ramalho</div>
<div class="org">AcousticComms</div>
</div>
</dd>
</dl>
</div>
<h1 id="rfcnum">RFC 8867</h1>
<h1 id="title">Test Cases for Evaluating Congestion Control for Interactive Real-Time Media</h1>
<section id="section-abstract">
      <h2 id="abstract"><a href="#abstract" class="selfRef">Abstract</a></h2>
<p id="section-abstract-1">The Real-time Transport Protocol (RTP) is used to transmit media in
      multimedia telephony applications. These applications are typically
      required to implement congestion control. This document describes the
      test cases to be used in the performance evaluation of such congestion
      control algorithms in a controlled environment.<a href="#section-abstract-1" class="pilcrow">¶</a></p>
</section>
<div id="status-of-memo">
<section id="section-boilerplate.1">
        <h2 id="name-status-of-this-memo">
<a href="#name-status-of-this-memo" class="section-name selfRef">Status of This Memo</a>
        </h2>
<p id="section-boilerplate.1-1">
            This document is not an Internet Standards Track specification; it is
            published for informational purposes.<a href="#section-boilerplate.1-1" class="pilcrow">¶</a></p>
<p id="section-boilerplate.1-2">
            This document is a product of the Internet Engineering Task Force
            (IETF).  It represents the consensus of the IETF community.  It has
            received public review and has been approved for publication by the
            Internet Engineering Steering Group (IESG).  Not all documents
            approved by the IESG are candidates for any level of Internet
            Standard; see Section 2 of RFC 7841.<a href="#section-boilerplate.1-2" class="pilcrow">¶</a></p>
<p id="section-boilerplate.1-3">
            Information about the current status of this document, any
            errata, and how to provide feedback on it may be obtained at
            <span><a href="https://www.rfc-editor.org/info/rfc8867">https://www.rfc-editor.org/info/rfc8867</a></span>.<a href="#section-boilerplate.1-3" class="pilcrow">¶</a></p>
</section>
</div>
<div id="copyright">
<section id="section-boilerplate.2">
        <h2 id="name-copyright-notice">
<a href="#name-copyright-notice" class="section-name selfRef">Copyright Notice</a>
        </h2>
<p id="section-boilerplate.2-1">
            Copyright (c) 2021 IETF Trust and the persons identified as the
            document authors. All rights reserved.<a href="#section-boilerplate.2-1" class="pilcrow">¶</a></p>
<p id="section-boilerplate.2-2">
            This document is subject to BCP 78 and the IETF Trust's Legal
            Provisions Relating to IETF Documents
            (<span><a href="https://trustee.ietf.org/license-info">https://trustee.ietf.org/license-info</a></span>) 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.<a href="#section-boilerplate.2-2" class="pilcrow">¶</a></p>
</section>
</div>
<div id="toc">
<section id="section-toc.1">
        <a href="#" onclick="scroll(0,0)" class="toplink">▲</a><h2 id="name-table-of-contents">
<a href="#name-table-of-contents" class="section-name selfRef">Table of Contents</a>
        </h2>
<nav class="toc"><ul class="compact toc ulEmpty">
<li class="compact toc ulEmpty" id="section-toc.1-1.1">
            <p id="section-toc.1-1.1.1" class="keepWithNext"><a href="#section-1" class="xref">1</a>.  <a href="#name-introduction" class="xref">Introduction</a><a href="#section-toc.1-1.1.1" class="pilcrow">¶</a></p>
</li>
          <li class="compact toc ulEmpty" id="section-toc.1-1.2">
            <p id="section-toc.1-1.2.1" class="keepWithNext"><a href="#section-2" class="xref">2</a>.  <a href="#name-terminology" class="xref">Terminology</a><a href="#section-toc.1-1.2.1" class="pilcrow">¶</a></p>
</li>
          <li class="compact toc ulEmpty" id="section-toc.1-1.3">
            <p id="section-toc.1-1.3.1" class="keepWithNext"><a href="#section-3" class="xref">3</a>.  <a href="#name-structure-of-test-cases" class="xref">Structure of Test Cases</a><a href="#section-toc.1-1.3.1" class="pilcrow">¶</a></p>
</li>
          <li class="compact toc ulEmpty" id="section-toc.1-1.4">
            <p id="section-toc.1-1.4.1"><a href="#section-4" class="xref">4</a>.  <a href="#name-recommended-evaluation-sett" class="xref">Recommended Evaluation Settings</a><a href="#section-toc.1-1.4.1" class="pilcrow">¶</a></p>
<ul class="toc compact ulEmpty">
<li class="toc compact ulEmpty" id="section-toc.1-1.4.2.1">
                <p id="section-toc.1-1.4.2.1.1"><a href="#section-4.1" class="xref">4.1</a>.  <a href="#name-evaluation-metrics" class="xref">Evaluation Metrics</a><a href="#section-toc.1-1.4.2.1.1" class="pilcrow">¶</a></p>
</li>
              <li class="toc compact ulEmpty" id="section-toc.1-1.4.2.2">
                <p id="section-toc.1-1.4.2.2.1"><a href="#section-4.2" class="xref">4.2</a>.  <a href="#name-path-characteristics" class="xref">Path Characteristics</a><a href="#section-toc.1-1.4.2.2.1" class="pilcrow">¶</a></p>
</li>
              <li class="toc compact ulEmpty" id="section-toc.1-1.4.2.3">
                <p id="section-toc.1-1.4.2.3.1"><a href="#section-4.3" class="xref">4.3</a>.  <a href="#name-media-source" class="xref">Media Source</a><a href="#section-toc.1-1.4.2.3.1" class="pilcrow">¶</a></p>
</li>
            </ul>
</li>
          <li class="compact toc ulEmpty" id="section-toc.1-1.5">
            <p id="section-toc.1-1.5.1"><a href="#section-5" class="xref">5</a>.  <a href="#name-basic-test-cases" class="xref">Basic Test Cases</a><a href="#section-toc.1-1.5.1" class="pilcrow">¶</a></p>
<ul class="toc compact ulEmpty">
<li class="toc compact ulEmpty" id="section-toc.1-1.5.2.1">
                <p id="section-toc.1-1.5.2.1.1"><a href="#section-5.1" class="xref">5.1</a>.  <a href="#name-variable-available-capacity" class="xref">Variable Available Capacity with a Single Flow</a><a href="#section-toc.1-1.5.2.1.1" class="pilcrow">¶</a></p>
</li>
              <li class="toc compact ulEmpty" id="section-toc.1-1.5.2.2">
                <p id="section-toc.1-1.5.2.2.1"><a href="#section-5.2" class="xref">5.2</a>.  <a href="#name-variable-available-capacity-" class="xref">Variable Available Capacity with Multiple Flows</a><a href="#section-toc.1-1.5.2.2.1" class="pilcrow">¶</a></p>
</li>
              <li class="toc compact ulEmpty" id="section-toc.1-1.5.2.3">
                <p id="section-toc.1-1.5.2.3.1"><a href="#section-5.3" class="xref">5.3</a>.  <a href="#name-congested-feedback-link-wit" class="xref">Congested Feedback Link with Bi-directional Media Flows</a><a href="#section-toc.1-1.5.2.3.1" class="pilcrow">¶</a></p>
</li>
              <li class="toc compact ulEmpty" id="section-toc.1-1.5.2.4">
                <p id="section-toc.1-1.5.2.4.1"><a href="#section-5.4" class="xref">5.4</a>.  <a href="#name-competing-media-flows-with-" class="xref">Competing Media Flows with the Same Congestion Control Algorithm</a><a href="#section-toc.1-1.5.2.4.1" class="pilcrow">¶</a></p>
</li>
              <li class="toc compact ulEmpty" id="section-toc.1-1.5.2.5">
                <p id="section-toc.1-1.5.2.5.1"><a href="#section-5.5" class="xref">5.5</a>.  <a href="#name-round-trip-time-fairness" class="xref">Round Trip Time Fairness</a><a href="#section-toc.1-1.5.2.5.1" class="pilcrow">¶</a></p>
</li>
              <li class="toc compact ulEmpty" id="section-toc.1-1.5.2.6">
                <p id="section-toc.1-1.5.2.6.1"><a href="#section-5.6" class="xref">5.6</a>.  <a href="#name-media-flow-competing-with-a" class="xref">Media Flow Competing with a Long TCP Flow</a><a href="#section-toc.1-1.5.2.6.1" class="pilcrow">¶</a></p>
</li>
              <li class="toc compact ulEmpty" id="section-toc.1-1.5.2.7">
                <p id="section-toc.1-1.5.2.7.1"><a href="#section-5.7" class="xref">5.7</a>.  <a href="#name-media-flow-competing-with-s" class="xref">Media Flow Competing with Short TCP Flows</a><a href="#section-toc.1-1.5.2.7.1" class="pilcrow">¶</a></p>
</li>
              <li class="toc compact ulEmpty" id="section-toc.1-1.5.2.8">
                <p id="section-toc.1-1.5.2.8.1"><a href="#section-5.8" class="xref">5.8</a>.  <a href="#name-media-pause-and-resume" class="xref">Media Pause and Resume</a><a href="#section-toc.1-1.5.2.8.1" class="pilcrow">¶</a></p>
</li>
            </ul>
</li>
          <li class="compact toc ulEmpty" id="section-toc.1-1.6">
            <p id="section-toc.1-1.6.1"><a href="#section-6" class="xref">6</a>.  <a href="#name-other-potential-test-cases" class="xref">Other Potential Test Cases</a><a href="#section-toc.1-1.6.1" class="pilcrow">¶</a></p>
<ul class="toc compact ulEmpty">
<li class="toc compact ulEmpty" id="section-toc.1-1.6.2.1">
                <p id="section-toc.1-1.6.2.1.1"><a href="#section-6.1" class="xref">6.1</a>.  <a href="#name-media-flows-with-priority" class="xref">Media Flows with Priority</a><a href="#section-toc.1-1.6.2.1.1" class="pilcrow">¶</a></p>
</li>
              <li class="toc compact ulEmpty" id="section-toc.1-1.6.2.2">
                <p id="section-toc.1-1.6.2.2.1"><a href="#section-6.2" class="xref">6.2</a>.  <a href="#name-explicit-congestion-notific" class="xref">Explicit Congestion Notification Usage</a><a href="#section-toc.1-1.6.2.2.1" class="pilcrow">¶</a></p>
</li>
              <li class="toc compact ulEmpty" id="section-toc.1-1.6.2.3">
                <p id="section-toc.1-1.6.2.3.1"><a href="#section-6.3" class="xref">6.3</a>.  <a href="#name-multiple-bottlenecks" class="xref">Multiple Bottlenecks</a><a href="#section-toc.1-1.6.2.3.1" class="pilcrow">¶</a></p>
</li>
            </ul>
</li>
          <li class="compact toc ulEmpty" id="section-toc.1-1.7">
            <p id="section-toc.1-1.7.1"><a href="#section-7" class="xref">7</a>.  <a href="#name-wireless-access-links" class="xref">Wireless Access Links</a><a href="#section-toc.1-1.7.1" class="pilcrow">¶</a></p>
</li>
          <li class="compact toc ulEmpty" id="section-toc.1-1.8">
            <p id="section-toc.1-1.8.1"><a href="#section-8" class="xref">8</a>.  <a href="#name-security-considerations" class="xref">Security Considerations</a><a href="#section-toc.1-1.8.1" class="pilcrow">¶</a></p>
</li>
          <li class="compact toc ulEmpty" id="section-toc.1-1.9">
            <p id="section-toc.1-1.9.1"><a href="#section-9" class="xref">9</a>.  <a href="#name-iana-considerations" class="xref">IANA Considerations</a><a href="#section-toc.1-1.9.1" class="pilcrow">¶</a></p>
</li>
          <li class="compact toc ulEmpty" id="section-toc.1-1.10">
            <p id="section-toc.1-1.10.1"><a href="#section-10" class="xref">10</a>. <a href="#name-references" class="xref">References</a><a href="#section-toc.1-1.10.1" class="pilcrow">¶</a></p>
<ul class="toc compact ulEmpty">
<li class="toc compact ulEmpty" id="section-toc.1-1.10.2.1">
                <p id="section-toc.1-1.10.2.1.1"><a href="#section-10.1" class="xref">10.1</a>.  <a href="#name-normative-references" class="xref">Normative References</a><a href="#section-toc.1-1.10.2.1.1" class="pilcrow">¶</a></p>
</li>
              <li class="toc compact ulEmpty" id="section-toc.1-1.10.2.2">
                <p id="section-toc.1-1.10.2.2.1"><a href="#section-10.2" class="xref">10.2</a>.  <a href="#name-informative-references" class="xref">Informative References</a><a href="#section-toc.1-1.10.2.2.1" class="pilcrow">¶</a></p>
</li>
            </ul>
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          <li class="compact toc ulEmpty" id="section-toc.1-1.11">
            <p id="section-toc.1-1.11.1"><a href="#section-appendix.a" class="xref"></a><a href="#name-acknowledgments" class="xref">Acknowledgments</a><a href="#section-toc.1-1.11.1" class="pilcrow">¶</a></p>
</li>
          <li class="compact toc ulEmpty" id="section-toc.1-1.12">
            <p id="section-toc.1-1.12.1"><a href="#section-appendix.b" class="xref"></a><a href="#name-authors-addresses" class="xref">Authors' Addresses</a><a href="#section-toc.1-1.12.1" class="pilcrow">¶</a></p>
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        </ul>
</nav>
</section>
</div>
<section id="section-1">
      <h2 id="name-introduction">
<a href="#section-1" class="section-number selfRef">1. </a><a href="#name-introduction" class="section-name selfRef">Introduction</a>
      </h2>
<p id="section-1-1">This memo describes a set of test cases for evaluating congestion
      control algorithm proposals in controlled environments for real-time
      interactive media. It is based on the guidelines enumerated in <span>[<a href="#RFC8868" class="xref">RFC8868</a>]</span> and the requirements discussed
      in <span>[<a href="#RFC8836" class="xref">RFC8836</a>]</span>. The test cases cover
      basic usage scenarios and are described using a common structure, which
      allows for additional test cases to be added to those described herein
      to accommodate other topologies and/or the  modeling of different path
      characteristics. The described test cases in this memo should be used to
      evaluate any proposed congestion control algorithm for real-time
      interactive media.<a href="#section-1-1" class="pilcrow">¶</a></p>
</section>
<div id="sec-terminology">
<section id="section-2">
      <h2 id="name-terminology">
<a href="#section-2" class="section-number selfRef">2. </a><a href="#name-terminology" class="section-name selfRef">Terminology</a>
      </h2>
<p id="section-2-1">The terminology defined in <span><a href="#RFC3550" class="xref">RTP</a> [<a href="#RFC3550" class="xref">RFC3550</a>]</span>, 
      <span><a href="#RFC3551" class="xref">RTP Profile for Audio and Video Conferences with
      Minimal Control</a> [<a href="#RFC3551" class="xref">RFC3551</a>]</span>, <span><a href="#RFC3611" class="xref">RTCP Extended Report
      (XR)</a> [<a href="#RFC3611" class="xref">RFC3611</a>]</span>, <span><a href="#RFC4585" class="xref">Extended RTP Profile for RTCP-based
      Feedback (RTP/AVPF)</a> [<a href="#RFC4585" class="xref">RFC4585</a>]</span>, and <span><a href="#RFC5506" class="xref">Support for
      Reduced-Size RTCP</a> [<a href="#RFC5506" class="xref">RFC5506</a>]</span> applies.<a href="#section-2-1" class="pilcrow">¶</a></p>
</section>
</div>
<div id="TS">
<section id="section-3">
      <h2 id="name-structure-of-test-cases">
<a href="#section-3" class="section-number selfRef">3. </a><a href="#name-structure-of-test-cases" class="section-name selfRef">Structure of Test Cases</a>
      </h2>
<p id="section-3-1">All the test cases in this document follow a basic structure allowing
      implementers to describe a new test scenario without repeatedly
      explaining common attributes. The structure includes a general
      description section that describes the test case and its motivation.
      Additionally the test case defines a set of attributes that characterize
      the testbed, for example, the network path between communicating peers
      and the diverse traffic sources.<a href="#section-3-1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-3-2">
        <dt id="section-3-2.1">Define the test case:</dt>
        <dd style="margin-left: 1.5em" id="section-3-2.2">
          <p id="section-3-2.2.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-3-2.2.2">
            <dt id="section-3-2.2.2.1">General description:</dt>
            <dd style="margin-left: 1.5em" id="section-3-2.2.2.2">describes the motivation and the goals
              of the test case.<a href="#section-3-2.2.2.2" class="pilcrow">¶</a>
</dd>
            <dd class="break"></dd>
<dt id="section-3-2.2.2.3">Expected behavior:</dt>
            <dd style="margin-left: 1.5em" id="section-3-2.2.2.4">describes the desired rate adaptation
              behavior.<a href="#section-3-2.2.2.4" class="pilcrow">¶</a>
</dd>
            <dd class="break"></dd>
<dt id="section-3-2.2.2.5">List of metrics to evaluate the desired behavior:</dt>
            <dd style="margin-left: 1.5em" id="section-3-2.2.2.6">
              this indicates the minimum set of metrics (e.g., link
              utilization, media sending rate) that a proposed algorithm needs
              to measure to validate the expected rate adaptation behavior. It
              should also indicate the time granularity (e.g., averaged over
              10 ms, 100 ms, or 1 s) for measuring certain metrics. Typical
              measurement interval is 200 ms.<a href="#section-3-2.2.2.6" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
</dl>
</dd>
        <dd class="break"></dd>
<dt id="section-3-2.3">Define testbed topology:</dt>
        <dd style="margin-left: 1.5em" id="section-3-2.4">
          <p id="section-3-2.4.1"><br></p>
<p id="section-3-2.4.2">Every test case needs to define an
          evaluation testbed topology. <a href="#fig-eval-topo" class="xref">Figure 1</a> shows
          such an evaluation topology. In this evaluation topology, S1..Sn are
          traffic sources. These sources generate media traffic and use the
          congestion control algorithm(s) under investigation. R1..Rn are the
          corresponding receivers. A test case can have one or more such
          traffic sources (S) and their corresponding receivers (R). The path
          from the source to destination is denoted as "forward", and the path
          from a destination to a source is denoted as "backward". The
          following basic structure of the test case has been described from
          the perspective of media-generating endpoints attached on the
          left-hand side of <a href="#fig-eval-topo" class="xref">Figure 1</a>. In this setup, the
          media flows are transported in the forward direction, and the corresponding
          feedback/control messages are transported in the backward direction.
          However, it is also possible to set up the test with media in both
          forward and backward directions. In that case, unless otherwise
          specified by the test case, it is expected that the backward path
          does not introduce any congestion-related impairments and has enough
          capacity to accommodate both media and feedback/control messages. It
          should be noted that, depending on the test cases, it is possible to
          have different path characteristics in either of the
          directions.<a href="#section-3-2.4.2" class="pilcrow">¶</a></p>
<span id="name-example-of-a-testbed-topolo"></span><div id="fig-eval-topo">
<figure id="figure-1">
            <div class="artwork art-text alignLeft" id="section-3-2.4.3.1">
<pre>
+---+                                                        +---+
|S1 |====== \               Forward --&gt;             / =======|R1 |
+---+       \\                                     //        +---+
             \\                                   //
+---+       +-----+                            +-----+       +---+
|S2 |=======|  A  |---------------------------&gt;|  B  |=======|R2 |
+---+       |     |&lt;---------------------------|     |       +---+
            +-----+                            +-----+
(...)         //                                  \\         (...)
             //          &lt;-- Backward              \\
+---+       //                                      \\       +---+
|Sn |====== /                                        \ ======|Rn |
+---+                                                        +---+
</pre>
</div>
<figcaption><a href="#figure-1" class="selfRef">Figure 1</a>:
<a href="#name-example-of-a-testbed-topolo" class="selfRef">Example of a Testbed Topology</a>
            </figcaption></figure>
</div>
<p id="section-3-2.4.4">In a testbed environment with real equipment, there may
          exist a significant amount of unwanted traffic on the portions of
          the network path between the endpoints. Some of this traffic may be
          generated by other processes on the endpoints themselves (e.g.,
          discovery protocols) or by other endpoints not presently under test.
          Such unwanted traffic should be removed or avoided to the greatest
          extent possible.<a href="#section-3-2.4.4" class="pilcrow">¶</a></p>
</dd>
        <dd class="break"></dd>
<dt id="section-3-2.5">Define testbed attributes:</dt>
        <dd style="margin-left: 1.5em" id="section-3-2.6">
          <p id="section-3-2.6.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-3-2.6.2">
            <dt id="section-3-2.6.2.1">Duration:</dt>
            <dd style="margin-left: 1.5em" id="section-3-2.6.2.2">defines the duration of the test in seconds.<a href="#section-3-2.6.2.2" class="pilcrow">¶</a>
</dd>
            <dd class="break"></dd>
<dt id="section-3-2.6.2.3">Path characteristics:</dt>
            <dd style="margin-left: 1.5em" id="section-3-2.6.2.4">
              <p id="section-3-2.6.2.4.1">defines the end-to-end transport level
              path characteristics of the testbed for a particular test case.
              Two sets of attributes describe the path characteristics, one
              for the forward path and the other for the backward path. The
              path characteristics for a particular path direction are
              applicable to all the sources "S" sending traffic on that path.
              If only one attribute is specified, it is used for both path
              directions; however, unless specified the reverse path has no
              capacity restrictions and no path loss.<a href="#section-3-2.6.2.4.1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-3-2.6.2.4.2">
                <dt id="section-3-2.6.2.4.2.1">Path direction:</dt>
                <dd style="margin-left: 1.5em" id="section-3-2.6.2.4.2.2">forward or backward.<a href="#section-3-2.6.2.4.2.2" class="pilcrow">¶</a>
</dd>
                <dd class="break"></dd>
<dt id="section-3-2.6.2.4.2.3">Minimum bottleneck-link capacity:</dt>
                <dd style="margin-left: 1.5em" id="section-3-2.6.2.4.2.4">defines the minimum capacity of the
                  end-to-end path.<a href="#section-3-2.6.2.4.2.4" class="pilcrow">¶</a>
</dd>
                <dd class="break"></dd>
<dt id="section-3-2.6.2.4.2.5">Reference bottleneck capacity:</dt>
                <dd style="margin-left: 1.5em" id="section-3-2.6.2.4.2.6">defines a reference value
                  for the bottleneck capacity for test cases with time-varying
                  bottleneck capacities. All bottleneck capacities will be
                  specified as a ratio with respect to the reference capacity
                  value.<a href="#section-3-2.6.2.4.2.6" class="pilcrow">¶</a>
</dd>
                <dd class="break"></dd>
<dt id="section-3-2.6.2.4.2.7">One-way propagation delay:</dt>
                <dd style="margin-left: 1.5em" id="section-3-2.6.2.4.2.8">describes the end-to-end
                  latency along the path when network queues are empty, i.e.,
                  the time it takes for a packet to go from the sender to the
                  receiver without encountering any queuing delay.<a href="#section-3-2.6.2.4.2.8" class="pilcrow">¶</a>
</dd>
                <dd class="break"></dd>
<dt id="section-3-2.6.2.4.2.9">Maximum end-to-end jitter:</dt>
                <dd style="margin-left: 1.5em" id="section-3-2.6.2.4.2.10">defines the maximum jitter
                  that can be observed along the path.<a href="#section-3-2.6.2.4.2.10" class="pilcrow">¶</a>
</dd>
                <dd class="break"></dd>
<dt id="section-3-2.6.2.4.2.11">Bottleneck queue type:</dt>
                <dd style="margin-left: 1.5em" id="section-3-2.6.2.4.2.12">for example, "tail drop" <span>[<a href="#RFC7567" class="xref">RFC7567</a>]</span>, 
                  Flow Queue Controlled Delay (FQ-CoDel) <span>[<a href="#RFC8290" class="xref">RFC8290</a>]</span>, 
                  or Proportional Integral controller Enhanced (PIE) 
                  <span>[<a href="#RFC8033" class="xref">RFC8033</a>]</span>.<a href="#section-3-2.6.2.4.2.12" class="pilcrow">¶</a>
</dd>
                <dd class="break"></dd>
<dt id="section-3-2.6.2.4.2.13">Bottleneck queue size:</dt>
                <dd style="margin-left: 1.5em" id="section-3-2.6.2.4.2.14">defines the size of queue in terms
                  of queuing time when the queue is full (in
                  milliseconds).<a href="#section-3-2.6.2.4.2.14" class="pilcrow">¶</a>
</dd>
                <dd class="break"></dd>
<dt id="section-3-2.6.2.4.2.15">Path loss ratio:</dt>
                <dd style="margin-left: 1.5em" id="section-3-2.6.2.4.2.16">characterizes the non-congested,
                  additive losses to be generated on the end-to-end path.
                  This must describe the loss pattern or loss model used to
                  generate the losses.<a href="#section-3-2.6.2.4.2.16" class="pilcrow">¶</a>
</dd>
              <dd class="break"></dd>
</dl>
</dd>
            <dd class="break"></dd>
<dt id="section-3-2.6.2.5">Application-related:</dt>
            <dd style="margin-left: 1.5em" id="section-3-2.6.2.6">
              <p id="section-3-2.6.2.6.1">defines the traffic source behavior for
              implementing the test case:<a href="#section-3-2.6.2.6.1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-3-2.6.2.6.2">
                <dt id="section-3-2.6.2.6.2.1">Media traffic source:</dt>
                <dd style="margin-left: 1.5em" id="section-3-2.6.2.6.2.2">
                  <p id="section-3-2.6.2.6.2.2.1">defines the characteristics of the
                  media sources. When using more than one media source, the
                  different attributes are enumerated separately for each
                  different media source.<a href="#section-3-2.6.2.6.2.2.1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-3-2.6.2.6.2.2.2">
                    <dt id="section-3-2.6.2.6.2.2.2.1">Media type:</dt>
                    <dd style="margin-left: 1.5em" id="section-3-2.6.2.6.2.2.2.2">Video/Voice.<a href="#section-3-2.6.2.6.2.2.2.2" class="pilcrow">¶</a>
</dd>
                    <dd class="break"></dd>
<dt id="section-3-2.6.2.6.2.2.2.3">Media flow direction:</dt>
                    <dd style="margin-left: 1.5em" id="section-3-2.6.2.6.2.2.2.4">forward, backward, or both.<a href="#section-3-2.6.2.6.2.2.2.4" class="pilcrow">¶</a>
</dd>
                    <dd class="break"></dd>
<dt id="section-3-2.6.2.6.2.2.2.5">Number of media sources:</dt>
                    <dd style="margin-left: 1.5em" id="section-3-2.6.2.6.2.2.2.6">defines the total number of
                      media sources.<a href="#section-3-2.6.2.6.2.2.2.6" class="pilcrow">¶</a>
</dd>
                    <dd class="break"></dd>
<dt id="section-3-2.6.2.6.2.2.2.7">Media codec:</dt>
                    <dd style="margin-left: 1.5em" id="section-3-2.6.2.6.2.2.2.8">Constant Bit Rate (CBR) or Variable Bit
                      Rate (VBR).<a href="#section-3-2.6.2.6.2.2.2.8" class="pilcrow">¶</a>
</dd>
                    <dd class="break"></dd>
<dt id="section-3-2.6.2.6.2.2.2.9">Media source behavior:</dt>
                    <dd style="margin-left: 1.5em" id="section-3-2.6.2.6.2.2.2.10">
                      <p id="section-3-2.6.2.6.2.2.2.10.1">describes the media encoder
                      behavior. It defines the main parameters that affect the
                      adaptation behavior. This may include but is not limited
                      to the following:<a href="#section-3-2.6.2.6.2.2.2.10.1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-3-2.6.2.6.2.2.2.10.2">
                        <dt id="section-3-2.6.2.6.2.2.2.10.2.1">Adaptability:</dt>
                        <dd style="margin-left: 1.5em" id="section-3-2.6.2.6.2.2.2.10.2.2">describes the adaptation options.
                          For example, in the case of video, it defines the
                          following ranges of adaptation: bit rate, frame
                          rate, and video resolution. Similarly, in the case of
                          voice, it defines the range of bit rate adaptation,
                          the sampling rate variation, and the variation in
                          packetization interval.<a href="#section-3-2.6.2.6.2.2.2.10.2.2" class="pilcrow">¶</a>
</dd>
                        <dd class="break"></dd>
<dt id="section-3-2.6.2.6.2.2.2.10.2.3">Output variation:</dt>
                        <dd style="margin-left: 1.5em" id="section-3-2.6.2.6.2.2.2.10.2.4">for a VBR encoder, it defines
                          the encoder output variation from the average target
                          rate over a particular measurement interval. For
                          example, on average the encoder output may vary
                          between 5% to 15% above or below the average target
                          bit rate when measured over a 100 ms time window.
                          The time interval over which the variation is
                          specified must be provided.<a href="#section-3-2.6.2.6.2.2.2.10.2.4" class="pilcrow">¶</a>
</dd>
                        <dd class="break"></dd>
<dt id="section-3-2.6.2.6.2.2.2.10.2.5">Responsiveness to a new bit rate request:</dt>
                        <dd style="margin-left: 1.5em" id="section-3-2.6.2.6.2.2.2.10.2.6">the lag
                          in time between a new bit rate request from the
                          congestion control algorithm and actual rate changes
                          in encoder output. Depending on the encoder, this
                          value may be specified in absolute time (e.g., 10 ms
                          to 1000 ms) or other appropriate metric (e.g., next
                          frame interval time).<a href="#section-3-2.6.2.6.2.2.2.10.2.6" class="pilcrow">¶</a>
</dd>
                      <dd class="break"></dd>
</dl>
<p id="section-3-2.6.2.6.2.2.2.10.3"> More detailed discussions on expected media
                      source behavior, including those from synthetic video
                      traffic sources, can be found in <span>[<a href="#RFC8593" class="xref">RFC8593</a>]</span>.<a href="#section-3-2.6.2.6.2.2.2.10.3" class="pilcrow">¶</a></p>
</dd>
                    <dd class="break"></dd>
<dt id="section-3-2.6.2.6.2.2.2.11">Media content:</dt>
                    <dd style="margin-left: 1.5em" id="section-3-2.6.2.6.2.2.2.12">describes the chosen video scenario.
                      For example, video test sequences are available at
                      <span>[<a href="#xiph-seq" class="xref">xiph-seq</a>]</span> and <span>[<a href="#HEVC-seq" class="xref">HEVC-seq</a>]</span>.
                      Different video scenarios give different distributions of
                      video frames produced by the video encoder. Hence, it is
                      important to specify the media content used in a
                      particular test. If a synthetic video traffic source
                      <span>[<a href="#RFC8593" class="xref">RFC8593</a>]</span> is
                      used, then the synthetic video traffic source needs to
                      be configured according to the characteristics of the media
                      content specified.<a href="#section-3-2.6.2.6.2.2.2.12" class="pilcrow">¶</a>
</dd>
                    <dd class="break"></dd>
<dt id="section-3-2.6.2.6.2.2.2.13">Media timeline:</dt>
                    <dd style="margin-left: 1.5em" id="section-3-2.6.2.6.2.2.2.14">describes the point when the media
                      source is introduced and removed from the testbed. For
                      example, the media source may start transmitting
                      immediately when the test case begins, or after a few
                      seconds.<a href="#section-3-2.6.2.6.2.2.2.14" class="pilcrow">¶</a>
</dd>
                    <dd class="break"></dd>
<dt id="section-3-2.6.2.6.2.2.2.15">Startup behavior:</dt>
                    <dd style="margin-left: 1.5em" id="section-3-2.6.2.6.2.2.2.16">the media starts at a defined bit
                      rate, which may be the minimum, maximum bit rate, or a
                      value in between (in Kbps).<a href="#section-3-2.6.2.6.2.2.2.16" class="pilcrow">¶</a>
</dd>
                  <dd class="break"></dd>
</dl>
</dd>
                <dd class="break"></dd>
<dt id="section-3-2.6.2.6.2.3">Competing traffic source:</dt>
                <dd style="margin-left: 1.5em" id="section-3-2.6.2.6.2.4">
                  <p id="section-3-2.6.2.6.2.4.1">describes the characteristics
                  of the competing traffic source, the different types of
                  competing flows are enumerated in <span>[<a href="#RFC8868" class="xref">RFC8868</a>]</span>.<a href="#section-3-2.6.2.6.2.4.1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-3-2.6.2.6.2.4.2">
                    <dt id="section-3-2.6.2.6.2.4.2.1">Traffic direction:</dt>
                    <dd style="margin-left: 1.5em" id="section-3-2.6.2.6.2.4.2.2">forward, backward, or both.<a href="#section-3-2.6.2.6.2.4.2.2" class="pilcrow">¶</a>
</dd>
                    <dd class="break"></dd>
<dt id="section-3-2.6.2.6.2.4.2.3">Type of sources:</dt>
                    <dd style="margin-left: 1.5em" id="section-3-2.6.2.6.2.4.2.4">defines the types of competing
                      traffic sources. Types of competing traffic flows are
                      listed in <span>[<a href="#RFC8868" class="xref">RFC8868</a>]</span>.
                      For example, the number of TCP flows connected to a web
                      browser, the mean size and distribution of the content
                      downloaded.<a href="#section-3-2.6.2.6.2.4.2.4" class="pilcrow">¶</a>
</dd>
                    <dd class="break"></dd>
<dt id="section-3-2.6.2.6.2.4.2.5">Number of sources:</dt>
                    <dd style="margin-left: 1.5em" id="section-3-2.6.2.6.2.4.2.6">defines the total number of
                      competing sources of each media type per traffic
                      direction.<a href="#section-3-2.6.2.6.2.4.2.6" class="pilcrow">¶</a>
</dd>
                    <dd class="break"></dd>
<dt id="section-3-2.6.2.6.2.4.2.7">Congestion control:</dt>
                    <dd style="margin-left: 1.5em" id="section-3-2.6.2.6.2.4.2.8">enumerates the congestion control
                      used by each type of competing traffic.<a href="#section-3-2.6.2.6.2.4.2.8" class="pilcrow">¶</a>
</dd>
                    <dd class="break"></dd>
<dt id="section-3-2.6.2.6.2.4.2.9">Traffic timeline:</dt>
                    <dd style="margin-left: 1.5em" id="section-3-2.6.2.6.2.4.2.10">describes when the competing
                      traffic starts and ends in the test case.<a href="#section-3-2.6.2.6.2.4.2.10" class="pilcrow">¶</a>
</dd>
                  <dd class="break"></dd>
</dl>
</dd>
              <dd class="break"></dd>
</dl>
</dd>
            <dd class="break"></dd>
<dt id="section-3-2.6.2.7">Additional attributes:</dt>
            <dd style="margin-left: 1.5em" id="section-3-2.6.2.8">describes attributes essential for
              implementing a test case that are not included in the above
              structure. These attributes must be well defined, so that the
              other implementers of that particular test case are able to
              implement it easily.<a href="#section-3-2.6.2.8" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
</dl>
</dd>
      <dd class="break"></dd>
</dl>
<p id="section-3-3">Any attribute can have a set of values (enclosed within "[]"). Each
      member value of such a set must be treated as different value for the
      same attribute. It is desired to run separate tests for each such
      attribute value.<a href="#section-3-3" class="pilcrow">¶</a></p>
<p id="section-3-4">The test cases described in this document follow the above
      structure.<a href="#section-3-4" class="pilcrow">¶</a></p>
</section>
</div>
<div id="sec-rec-eval">
<section id="section-4">
      <h2 id="name-recommended-evaluation-sett">
<a href="#section-4" class="section-number selfRef">4. </a><a href="#name-recommended-evaluation-sett" class="section-name selfRef">Recommended Evaluation Settings</a>
      </h2>
<p id="section-4-1">This section describes recommended test case settings and could be
      overwritten by the respective test cases.<a href="#section-4-1" class="pilcrow">¶</a></p>
<div id="EM">
<section id="section-4.1">
        <h3 id="name-evaluation-metrics">
<a href="#section-4.1" class="section-number selfRef">4.1. </a><a href="#name-evaluation-metrics" class="section-name selfRef">Evaluation Metrics</a>
        </h3>
<p id="section-4.1-1">To evaluate the performance of the candidate algorithms, the
        implementers must log enough information to visualize the following
        metrics at a fine enough time granularity:<a href="#section-4.1-1" class="pilcrow">¶</a></p>
<ol start="1" type="1" class="normal type-1" id="section-4.1-2">
          <li id="section-4.1-2.1">
            <p id="section-4.1-2.1.1">Flow level:<a href="#section-4.1-2.1.1" class="pilcrow">¶</a></p>
<ol start="1" type="A" class="normal type-A" id="section-4.1-2.1.2">
              <li id="section-4.1-2.1.2.1">End-to-end delay for the congestion-controlled media
                flow(s). For example, end-to-end delay observed on the IP packet
                level and the video frame level.<a href="#section-4.1-2.1.2.1" class="pilcrow">¶</a>
</li>
              <li id="section-4.1-2.1.2.2">Variation in sending bit rate and throughput. Mainly
                observing the frequency and magnitude of oscillations.<a href="#section-4.1-2.1.2.2" class="pilcrow">¶</a>
</li>
              <li id="section-4.1-2.1.2.3">Packet losses observed at the receiving endpoint.<a href="#section-4.1-2.1.2.3" class="pilcrow">¶</a>
</li>
              <li id="section-4.1-2.1.2.4">Feedback message overhead.<a href="#section-4.1-2.1.2.4" class="pilcrow">¶</a>
</li>
              <li id="section-4.1-2.1.2.5">Convergence time. Time to reach steady state for the
                congestion-controlled media flow(s). Each occurrence of
                convergence during the test period needs to be presented.<a href="#section-4.1-2.1.2.5" class="pilcrow">¶</a>
</li>
            </ol>
</li>
          <li id="section-4.1-2.2">
            <p id="section-4.1-2.2.1">Transport level:<a href="#section-4.1-2.2.1" class="pilcrow">¶</a></p>
<ol start="1" type="A" class="normal type-A" id="section-4.1-2.2.2">
              <li id="section-4.1-2.2.2.1">Bandwidth utilization.<a href="#section-4.1-2.2.2.1" class="pilcrow">¶</a>
</li>
              <li id="section-4.1-2.2.2.2">Queue length (milliseconds at specified path capacity).<a href="#section-4.1-2.2.2.2" class="pilcrow">¶</a>
</li>
            </ol>
</li>
        </ol>
</section>
</div>
<div id="PC">
<section id="section-4.2">
        <h3 id="name-path-characteristics">
<a href="#section-4.2" class="section-number selfRef">4.2. </a><a href="#name-path-characteristics" class="section-name selfRef">Path Characteristics</a>
        </h3>
<p id="section-4.2-1">Each path between a sender and receiver as described in 
<a href="#fig-eval-topo" class="xref">Figure 1</a> has the following characteristics unless
        otherwise specified in the test case:<a href="#section-4.2-1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-4.2-2">
          <dt id="section-4.2-2.1">Path direction: </dt>
          <dd style="margin-left: 1.5em" id="section-4.2-2.2">forward and backward.<a href="#section-4.2-2.2" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-4.2-2.3">Reference bottleneck capacity: </dt>
          <dd style="margin-left: 1.5em" id="section-4.2-2.4">1 Mbps.<a href="#section-4.2-2.4" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-4.2-2.5">One-way propagation delay: </dt>
          <dd style="margin-left: 1.5em" id="section-4.2-2.6">50 ms. Implementers are encouraged to
            run the experiment with additional propagation delays mentioned in
            <span>[<a href="#RFC8868" class="xref">RFC8868</a>]</span>.<a href="#section-4.2-2.6" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-4.2-2.7">Maximum end-to-end jitter: </dt>
          <dd style="margin-left: 1.5em" id="section-4.2-2.8">30 ms. Jitter models are described in
            <span>[<a href="#RFC8868" class="xref">RFC8868</a>]</span>.<a href="#section-4.2-2.8" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-4.2-2.9">Bottleneck queue type: </dt>
          <dd style="margin-left: 1.5em" id="section-4.2-2.10">"tail drop". Implementers are encouraged
            to run the experiment with other Active Queue Management (AQM) schemes, such as FQ-CoDel and
            PIE.<a href="#section-4.2-2.10" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-4.2-2.11">Bottleneck queue size: </dt>
          <dd style="margin-left: 1.5em" id="section-4.2-2.12">300 ms.<a href="#section-4.2-2.12" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-4.2-2.13">Path loss ratio: </dt>
          <dd style="margin-left: 1.5em" id="section-4.2-2.14">0%.<a href="#section-4.2-2.14" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
</dl>
<p id="section-4.2-3">Examples of additional network parameters are discussed in <span>[<a href="#RFC8868" class="xref">RFC8868</a>]</span>.<a href="#section-4.2-3" class="pilcrow">¶</a></p>
<p id="section-4.2-4">For test cases involving time-varying bottleneck capacity, all
        capacity values are specified as a ratio with respect to a reference
        capacity value, so as to allow flexible scaling of capacity values
        along with media source rate range. There exist two different
        mechanisms for inducing path capacity variation: a) by explicitly
        modifying the value of physical link capacity, or b) by introducing
        background non-adaptive UDP traffic with time-varying traffic rate.
        Implementers are encouraged to run the experiments with both
        mechanisms for test cases specified in <a href="#VACS" class="xref">Section 5.1</a>, <a href="#VACM" class="xref">Section 5.2</a>, and <a href="#CFL" class="xref">Section 5.3</a>.<a href="#section-4.2-4" class="pilcrow">¶</a></p>
</section>
</div>
<div id="MS">
<section id="section-4.3">
        <h3 id="name-media-source">
<a href="#section-4.3" class="section-number selfRef">4.3. </a><a href="#name-media-source" class="section-name selfRef">Media Source</a>
        </h3>
<p id="section-4.3-1">Unless otherwise specified, each test case will include one or more
        media sources as described below:<a href="#section-4.3-1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-4.3-2">
          <dt id="section-4.3-2.1">Media type:</dt>
          <dd style="margin-left: 1.5em" id="section-4.3-2.2">
            <p id="section-4.3-2.2.1">Video<a href="#section-4.3-2.2.1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-4.3-2.2.2">
              <dt id="section-4.3-2.2.2.1">Media codec:</dt>
              <dd style="margin-left: 1.5em" id="section-4.3-2.2.2.2">VBR<a href="#section-4.3-2.2.2.2" class="pilcrow">¶</a>
</dd>
              <dd class="break"></dd>
<dt id="section-4.3-2.2.2.3">Media source behavior:</dt>
              <dd style="margin-left: 1.5em" id="section-4.3-2.2.2.4">
                <p id="section-4.3-2.2.2.4.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-4.3-2.2.2.4.2">
                  <dt id="section-4.3-2.2.2.4.2.1">Adaptability:</dt>
                  <dd style="margin-left: 1.5em" id="section-4.3-2.2.2.4.2.2">
                    <p id="section-4.3-2.2.2.4.2.2.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-4.3-2.2.2.4.2.2.2">
                      <dt id="section-4.3-2.2.2.4.2.2.2.1">Bit rate range:</dt>
                      <dd style="margin-left: 1.5em" id="section-4.3-2.2.2.4.2.2.2.2">
                        150 Kbps - 1.5 Mbps. In real-life
                        applications, the bit rate range can vary a lot
                        depending on the provided service; for example, the
                        maximum bit rate can be up to 4 Mbps. However, for
                        running tests to evaluate the congestion control
                        algorithms, it is more important to have a look at how
                        they react to a certain amount of bandwidth
                        change. Also it is possible that the media traffic
                        generator used in a particular simulator or testbed is
                        not capable of generating a higher bit rate. Hence, we
                        have selected a suitable bit rate range typical of
                        consumer-grade video conferencing applications in
                        designing the test case. If a different bit rate range
                        is used in the test cases, then the end-to-end path
                        capacity values will also need to be scaled
                        accordingly.<a href="#section-4.3-2.2.2.4.2.2.2.2" class="pilcrow">¶</a>
</dd>
                      <dd class="break"></dd>
<dt id="section-4.3-2.2.2.4.2.2.2.3">Frame resolution: </dt>
                      <dd style="margin-left: 1.5em" id="section-4.3-2.2.2.4.2.2.2.4">144p - 720p (or 1080p). This
                        resolution range is selected based on the bit rate
                        range. If a different bit rate range is used in the
                        test cases, then a suitable frame resolution range also needs
                        to be selected.<a href="#section-4.3-2.2.2.4.2.2.2.4" class="pilcrow">¶</a>
</dd>
                      <dd class="break"></dd>
<dt id="section-4.3-2.2.2.4.2.2.2.5">Frame rate: </dt>
                      <dd style="margin-left: 1.5em" id="section-4.3-2.2.2.4.2.2.2.6">10 fps - 30 fps. This frame rate range is
                        selected based on the bit rate range. If a different
                        bit rate range is used in the test cases, then the
                        frame rate range also needs to be suitably adjusted.<a href="#section-4.3-2.2.2.4.2.2.2.6" class="pilcrow">¶</a>
</dd>
                    <dd class="break"></dd>
</dl>
</dd>
                  <dd class="break"></dd>
<dt id="section-4.3-2.2.2.4.2.3">Variation from target bit rate: </dt>
                  <dd style="margin-left: 1.5em" id="section-4.3-2.2.2.4.2.4">+/-5%. Unless otherwise
                    specified in the test case(s), bit rate variation should
                    be calculated over a one (1) second period of time.<a href="#section-4.3-2.2.2.4.2.4" class="pilcrow">¶</a>
</dd>
                  <dd class="break"></dd>
<dt id="section-4.3-2.2.2.4.2.5">Responsiveness to new bit rate request: </dt>
                  <dd style="margin-left: 1.5em" id="section-4.3-2.2.2.4.2.6">100 ms<a href="#section-4.3-2.2.2.4.2.6" class="pilcrow">¶</a>
</dd>
                <dd class="break"></dd>
</dl>
</dd>
              <dd class="break"></dd>
<dt id="section-4.3-2.2.2.5">Media content:</dt>
              <dd style="margin-left: 1.5em" id="section-4.3-2.2.2.6">The media content should represent a typical
                video conversational scenario with head and shoulder movement.
                We recommend using the Foreman video sequence <span>[<a href="#xiph-seq" class="xref">xiph-seq</a>]</span>.<a href="#section-4.3-2.2.2.6" class="pilcrow">¶</a>
</dd>
              <dd class="break"></dd>
<dt id="section-4.3-2.2.2.7">Media startup behavior:</dt>
              <dd style="margin-left: 1.5em" id="section-4.3-2.2.2.8">150 Kbps. It should be noted that
                applications can use smart ways to select an optimal startup
                bit rate value for a certain network condition. In such cases,
                the candidate proposals may show the effectiveness of such a
                smart approach as additional information for the evaluation
                process.<a href="#section-4.3-2.2.2.8" class="pilcrow">¶</a>
</dd>
            <dd class="break"></dd>
</dl>
</dd>
          <dd class="break"></dd>
<dt id="section-4.3-2.3">Media type:</dt>
          <dd style="margin-left: 1.5em" id="section-4.3-2.4">
            <p id="section-4.3-2.4.1">Audio<a href="#section-4.3-2.4.1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-4.3-2.4.2">
              <dt id="section-4.3-2.4.2.1">Media codec:   </dt>
              <dd style="margin-left: 1.5em" id="section-4.3-2.4.2.2">CBR<a href="#section-4.3-2.4.2.2" class="pilcrow">¶</a>
</dd>
              <dd class="break"></dd>
<dt id="section-4.3-2.4.2.3">Media bit rate:</dt>
              <dd style="margin-left: 1.5em" id="section-4.3-2.4.2.4">20 Kbps<a href="#section-4.3-2.4.2.4" class="pilcrow">¶</a>
</dd>
            <dd class="break"></dd>
</dl>
</dd>
        <dd class="break"></dd>
</dl>
</section>
</div>
</section>
</div>
<div id="TC">
<section id="section-5">
      <h2 id="name-basic-test-cases">
<a href="#section-5" class="section-number selfRef">5. </a><a href="#name-basic-test-cases" class="section-name selfRef">Basic Test Cases</a>
      </h2>
<div id="VACS">
<section id="section-5.1">
        <h3 id="name-variable-available-capacity">
<a href="#section-5.1" class="section-number selfRef">5.1. </a><a href="#name-variable-available-capacity" class="section-name selfRef">Variable Available Capacity with a Single Flow</a>
        </h3>
<p id="section-5.1-1">In this test case, the minimum bottleneck-link capacity between the two
        endpoints varies over time. This test is designed to measure the
        responsiveness of the candidate algorithm. This test tries to address
        the requirements in <span>[<a href="#RFC8836" class="xref">RFC8836</a>]</span>,
        which requires the algorithm to adapt the flow(s) and provide lower
        end-to-end latency when there exists:<a href="#section-5.1-1" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-5.1-2.1">an intermediate bottleneck<a href="#section-5.1-2.1" class="pilcrow">¶</a>
</li>
          <li class="normal" id="section-5.1-2.2">change in available capacity (e.g., due to interface change,
            routing change, abrupt arrival/departure of background
            non-adaptive traffic)<a href="#section-5.1-2.2" class="pilcrow">¶</a>
</li>
          <li class="normal" id="section-5.1-2.3">maximum media bit rate is greater than link capacity. In this
            case, when the application tries to ramp up to its maximum bit
            rate, since the link capacity is limited to a lower value, the
            congestion control scheme is expected to stabilize the sending bit
            rate close to the available bottleneck capacity.<a href="#section-5.1-2.3" class="pilcrow">¶</a>
</li>
        </ul>
<p id="section-5.1-3">It should be noted that the exact variation in available
        capacity due to any of the above depends on the underlying
        technologies. Hence, we describe a set of known factors, which may be
        extended to devise a more specific test case targeting certain
        behaviors in a certain network environment.<a href="#section-5.1-3" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-5.1-4">
          <dt id="section-5.1-4.1">Expected behavior:</dt>
          <dd style="margin-left: 1.5em" id="section-5.1-4.2">The candidate algorithm is expected to detect
        the path capacity constraint, converge to the bottleneck link's
        capacity, and adapt the flow to avoid unwanted media rate oscillation
        when the sending bit rate is approaching the bottleneck link's
        capacity. Such oscillations might occur when the media flow(s)
        attempts to reach its maximum bit rate but overshoots the usage of the
        available bottleneck capacity, then to rectify, it reduces the bit rate
        and starts to ramp up again.<a href="#section-5.1-4.2" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-5.1-4.3">Evaluation metrics:</dt>
          <dd style="margin-left: 1.5em" id="section-5.1-4.4">As described in <a href="#EM" class="xref">Section 4.1</a>.<a href="#section-5.1-4.4" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-5.1-4.5">Testbed topology:</dt>
          <dd style="margin-left: 1.5em" id="section-5.1-4.6">One media source S1 is connected to the
        corresponding R1. The media traffic is transported over the forward
        path and corresponding feedback/control traffic is transported over
        the backward path.<a href="#section-5.1-4.6" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
</dl>
<span id="name-testbed-topology-for-limite"></span><div id="fig-eval-topo-4-2">
<figure id="figure-2">
          <div class="artwork art-text alignLeft" id="section-5.1-5.1">
<pre>
                             Forward --&gt;
+---+       +-----+                               +-----+       +---+
|S1 |=======|  A  |------------------------------&gt;|  B  |=======|R1 |
+---+       |     |&lt;------------------------------|     |       +---+
            +-----+                               +-----+
                          &lt;-- Backward
</pre>
</div>
<figcaption><a href="#figure-2" class="selfRef">Figure 2</a>:
<a href="#name-testbed-topology-for-limite" class="selfRef">Testbed Topology for Limited Link Capacity</a>
          </figcaption></figure>
</div>
<span class="break"></span><dl class="dlParallel" id="section-5.1-6">
          <dt id="section-5.1-6.1">Testbed attributes:</dt>
          <dd style="margin-left: 1.5em" id="section-5.1-6.2">
            <p id="section-5.1-6.2.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.1-6.2.2">
              <dt id="section-5.1-6.2.2.1">Test duration:</dt>
              <dd style="margin-left: 1.5em" id="section-5.1-6.2.2.2">100 s<a href="#section-5.1-6.2.2.2" class="pilcrow">¶</a>
</dd>
              <dd class="break"></dd>
<dt id="section-5.1-6.2.2.3">Path characteristics:</dt>
              <dd style="margin-left: 1.5em" id="section-5.1-6.2.2.4">as described in <a href="#PC" class="xref">Section 4.2</a><a href="#section-5.1-6.2.2.4" class="pilcrow">¶</a>
</dd>
              <dd class="break"></dd>
<dt id="section-5.1-6.2.2.5">Application-related:</dt>
              <dd style="margin-left: 1.5em" id="section-5.1-6.2.2.6">
                <p id="section-5.1-6.2.2.6.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.1-6.2.2.6.2">
                  <dt id="section-5.1-6.2.2.6.2.1">Media Traffic:</dt>
                  <dd style="margin-left: 1.5em" id="section-5.1-6.2.2.6.2.2">
                    <p id="section-5.1-6.2.2.6.2.2.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.1-6.2.2.6.2.2.2">
                      <dt id="section-5.1-6.2.2.6.2.2.2.1">Media type:</dt>
                      <dd style="margin-left: 1.5em" id="section-5.1-6.2.2.6.2.2.2.2">
                        <p id="section-5.1-6.2.2.6.2.2.2.2.1">Video<a href="#section-5.1-6.2.2.6.2.2.2.2.1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-5.1-6.2.2.6.2.2.2.2.2">
                          <dt id="section-5.1-6.2.2.6.2.2.2.2.2.1">Media direction:</dt>
                          <dd style="margin-left: 1.5em" id="section-5.1-6.2.2.6.2.2.2.2.2.2">forward<a href="#section-5.1-6.2.2.6.2.2.2.2.2.2" class="pilcrow">¶</a>
</dd>
                          <dd class="break"></dd>
<dt id="section-5.1-6.2.2.6.2.2.2.2.2.3">Number of media sources:</dt>
                          <dd style="margin-left: 1.5em" id="section-5.1-6.2.2.6.2.2.2.2.2.4">one (1)<a href="#section-5.1-6.2.2.6.2.2.2.2.2.4" class="pilcrow">¶</a>
</dd>
                          <dd class="break"></dd>
<dt id="section-5.1-6.2.2.6.2.2.2.2.2.5">Media timeline:</dt>
                          <dd style="margin-left: 1.5em" id="section-5.1-6.2.2.6.2.2.2.2.2.6">
                            <p id="section-5.1-6.2.2.6.2.2.2.2.2.6.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.1-6.2.2.6.2.2.2.2.2.6.2">
                              <dt id="section-5.1-6.2.2.6.2.2.2.2.2.6.2.1">Start time:</dt>
                              <dd style="margin-left: 1.5em" id="section-5.1-6.2.2.6.2.2.2.2.2.6.2.2">0 s<a href="#section-5.1-6.2.2.6.2.2.2.2.2.6.2.2" class="pilcrow">¶</a>
</dd>
                              <dd class="break"></dd>
<dt id="section-5.1-6.2.2.6.2.2.2.2.2.6.2.3">End time:</dt>
                              <dd style="margin-left: 1.5em" id="section-5.1-6.2.2.6.2.2.2.2.2.6.2.4">99 s<a href="#section-5.1-6.2.2.6.2.2.2.2.2.6.2.4" class="pilcrow">¶</a>
</dd>
                            <dd class="break"></dd>
</dl>
</dd>
                        <dd class="break"></dd>
</dl>
</dd>
                      <dd class="break"></dd>
<dt id="section-5.1-6.2.2.6.2.2.2.3">Media type:</dt>
                      <dd style="margin-left: 1.5em" id="section-5.1-6.2.2.6.2.2.2.4">
                        <p id="section-5.1-6.2.2.6.2.2.2.4.1">Audio<a href="#section-5.1-6.2.2.6.2.2.2.4.1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-5.1-6.2.2.6.2.2.2.4.2">
                          <dt id="section-5.1-6.2.2.6.2.2.2.4.2.1">Media direction:</dt>
                          <dd style="margin-left: 1.5em" id="section-5.1-6.2.2.6.2.2.2.4.2.2">forward<a href="#section-5.1-6.2.2.6.2.2.2.4.2.2" class="pilcrow">¶</a>
</dd>
                          <dd class="break"></dd>
<dt id="section-5.1-6.2.2.6.2.2.2.4.2.3">Number of media sources:</dt>
                          <dd style="margin-left: 1.5em" id="section-5.1-6.2.2.6.2.2.2.4.2.4">one (1)<a href="#section-5.1-6.2.2.6.2.2.2.4.2.4" class="pilcrow">¶</a>
</dd>
                          <dd class="break"></dd>
<dt id="section-5.1-6.2.2.6.2.2.2.4.2.5">Media timeline:</dt>
                          <dd style="margin-left: 1.5em" id="section-5.1-6.2.2.6.2.2.2.4.2.6">
                            <p id="section-5.1-6.2.2.6.2.2.2.4.2.6.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.1-6.2.2.6.2.2.2.4.2.6.2">
                              <dt id="section-5.1-6.2.2.6.2.2.2.4.2.6.2.1">Start time:</dt>
                              <dd style="margin-left: 1.5em" id="section-5.1-6.2.2.6.2.2.2.4.2.6.2.2">0 s<a href="#section-5.1-6.2.2.6.2.2.2.4.2.6.2.2" class="pilcrow">¶</a>
</dd>
                              <dd class="break"></dd>
<dt id="section-5.1-6.2.2.6.2.2.2.4.2.6.2.3">End time:</dt>
                              <dd style="margin-left: 1.5em" id="section-5.1-6.2.2.6.2.2.2.4.2.6.2.4">99 s<a href="#section-5.1-6.2.2.6.2.2.2.4.2.6.2.4" class="pilcrow">¶</a>
</dd>
                            <dd class="break"></dd>
</dl>
</dd>
                        <dd class="break"></dd>
</dl>
</dd>
                    <dd class="break"></dd>
</dl>
</dd>
                  <dd class="break"></dd>
<dt id="section-5.1-6.2.2.6.2.3">Competing traffic:</dt>
                  <dd style="margin-left: 1.5em" id="section-5.1-6.2.2.6.2.4">
                    <p id="section-5.1-6.2.2.6.2.4.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.1-6.2.2.6.2.4.2">
                      <dt id="section-5.1-6.2.2.6.2.4.2.1">Number of sources:</dt>
                      <dd style="margin-left: 1.5em" id="section-5.1-6.2.2.6.2.4.2.2">zero (0)<a href="#section-5.1-6.2.2.6.2.4.2.2" class="pilcrow">¶</a>
</dd>
                    <dd class="break"></dd>
</dl>
</dd>
                <dd class="break"></dd>
</dl>
</dd>
            <dd class="break"></dd>
</dl>
</dd>
          <dd class="break"></dd>
<dt id="section-5.1-6.3">Test-specific information:</dt>
          <dd style="margin-left: 1.5em" id="section-5.1-6.4">
            <p id="section-5.1-6.4.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.1-6.4.2">
              <dt id="section-5.1-6.4.2.1">One-way propagation delay:</dt>
              <dd style="margin-left: 1.5em" id="section-5.1-6.4.2.2">[50 ms, 100 ms]. On the forward path direction.<a href="#section-5.1-6.4.2.2" class="pilcrow">¶</a>
</dd>
            <dd class="break"></dd>
</dl>
<p id="section-5.1-6.4.3">This test uses bottleneck path capacity variation as listed
                    in <a href="#VACS_US" class="xref">Table 1</a>.<a href="#section-5.1-6.4.3" class="pilcrow">¶</a></p>
<p id="section-5.1-6.4.4">When using background non-adaptive UDP traffic to induce a
                    time-varying bottleneck, the physical path capacity remains
                    at 4 Mbps, and the UDP traffic source rate changes over time as
                    (4 - (Y x r)), where r is the Reference bottleneck capacity in
                    Mbps, and Y is the path capacity ratio specified in 
                    <a href="#VACS_US" class="xref">Table 1</a>.<a href="#section-5.1-6.4.4" class="pilcrow">¶</a></p>
</dd>
        <dd class="break"></dd>
</dl>
<span id="name-path-capacity-variation-pat"></span><div id="VACS_US">
<table class="center" id="table-1">
          <caption>
<a href="#table-1" class="selfRef">Table 1</a>:
<a href="#name-path-capacity-variation-pat" class="selfRef">Path Capacity Variation Pattern for the Forward Direction</a>
          </caption>
<thead>
            <tr>
              <th class="text-left" rowspan="1" colspan="1">Variation pattern index</th>
              <th class="text-left" rowspan="1" colspan="1">Path direction</th>
              <th class="text-left" rowspan="1" colspan="1">Start time</th>
              <th class="text-left" rowspan="1" colspan="1">Path capacity ratio</th>
            </tr>
          </thead>
          <tbody>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">One</td>
              <td class="text-left" rowspan="1" colspan="1">Forward</td>
              <td class="text-left" rowspan="1" colspan="1">0 s</td>
              <td class="text-left" rowspan="1" colspan="1">1.0</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">Two</td>
              <td class="text-left" rowspan="1" colspan="1">Forward</td>
              <td class="text-left" rowspan="1" colspan="1">40 s</td>
              <td class="text-left" rowspan="1" colspan="1">2.5</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">Three</td>
              <td class="text-left" rowspan="1" colspan="1">Forward</td>
              <td class="text-left" rowspan="1" colspan="1">60 s</td>
              <td class="text-left" rowspan="1" colspan="1">0.6</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">Four</td>
              <td class="text-left" rowspan="1" colspan="1">Forward</td>
              <td class="text-left" rowspan="1" colspan="1">80 s</td>
              <td class="text-left" rowspan="1" colspan="1">1.0</td>
            </tr>
          </tbody>
        </table>
</div>
<p id="section-5.1-8"></p>
</section>
</div>
<div id="VACM">
<section id="section-5.2">
        <h3 id="name-variable-available-capacity-">
<a href="#section-5.2" class="section-number selfRef">5.2. </a><a href="#name-variable-available-capacity-" class="section-name selfRef">Variable Available Capacity with Multiple Flows</a>
        </h3>
<p id="section-5.2-1">This test case is similar to <a href="#VACS" class="xref">Section 5.1</a>. However,
        this test will also consider persistent network load due to
        competing traffic.<a href="#section-5.2-1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-5.2-2">
          <dt id="section-5.2-2.1">Expected behavior:</dt>
          <dd style="margin-left: 1.5em" id="section-5.2-2.2">The candidate algorithm is expected to detect
        the variation in available capacity and adapt the media stream(s)
        accordingly. The flows stabilize around their maximum bit rate as the
        maximum link capacity is large enough to accommodate the flows. When
        the available capacity drops, the flows adapt by decreasing their
        sending bit rate, and when congestion disappears, the flows are again
        expected to ramp up.<a href="#section-5.2-2.2" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-5.2-2.3">Evaluation metrics:</dt>
          <dd style="margin-left: 1.5em" id="section-5.2-2.4">As described in <a href="#EM" class="xref">Section 4.1</a>.<a href="#section-5.2-2.4" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-5.2-2.5">Testbed topology:</dt>
          <dd style="margin-left: 1.5em" id="section-5.2-2.6">Two (2) media sources S1 and S2 are connected to
        their corresponding destinations R1 and R2. The media traffic is
        transported over the forward path and corresponding feedback/control
        traffic is transported over the backward path.<a href="#section-5.2-2.6" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
</dl>
<span id="name-testbed-topology-for-variab"></span><div id="fig-eval-topo-4-1">
<figure id="figure-3">
          <div class="artwork art-text alignLeft" id="section-5.2-3.1">
<pre>
+---+                                                         +---+
|S1 |===== \                                         / =======|R1 |
+---+      \\             Forward --&gt;               //        +---+
            \\                                     //
            +-----+                               +-----+
            |  A  |------------------------------&gt;|  B  |
            |     |&lt;------------------------------|     |
            +-----+                               +-----+
              //                                    \\
             //          &lt;-- Backward                \\
+---+       //                                        \\       +---+
|S2 |====== /                                          \ ======|R2 |
+---+                                                          +---+
</pre>
</div>
<figcaption><a href="#figure-3" class="selfRef">Figure 3</a>:
<a href="#name-testbed-topology-for-variab" class="selfRef">Testbed Topology for Variable Available Capacity</a>
          </figcaption></figure>
</div>
<span class="break"></span><dl class="dlParallel" id="section-5.2-4">
          <dt id="section-5.2-4.1">Testbed attributes:</dt>
          <dd style="margin-left: 1.5em" id="section-5.2-4.2">Testbed attributes are similar to those described in <a href="#VACS" class="xref">Section 5.1</a>, 
        except for the test-specific capacity variation setup.<a href="#section-5.2-4.2" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-5.2-4.3">Test-specific information:</dt>
          <dd style="margin-left: 1.5em" id="section-5.2-4.4">This test uses path capacity variation
        as listed in <a href="#VACM_US" class="xref">Table 2</a> with a corresponding end time of
        125 seconds. The reference bottleneck capacity is 2 Mbps. When using
        background non-adaptive UDP traffic to induce time-varying bottleneck
        for congestion-controlled media flows, the physical path capacity is
        4 Mbps, and the UDP traffic source rate changes over time as (4 - (Y x
        r)), where r is the Reference bottleneck capacity in Mbps, and Y is the
        path capacity ratio specified in <a href="#VACM_US" class="xref">Table 2</a>.<a href="#section-5.2-4.4" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
</dl>
<span id="name-path-capacity-variation-patt"></span><div id="VACM_US">
<table class="center" id="table-2">
          <caption>
<a href="#table-2" class="selfRef">Table 2</a>:
<a href="#name-path-capacity-variation-patt" class="selfRef">Path Capacity Variation Pattern for the Forward Direction</a>
          </caption>
<thead>
            <tr>
              <th class="text-left" rowspan="1" colspan="1">Variation pattern index</th>
              <th class="text-left" rowspan="1" colspan="1">Path direction</th>
              <th class="text-left" rowspan="1" colspan="1">Start time</th>
              <th class="text-left" rowspan="1" colspan="1">Path capacity ratio</th>
            </tr>
          </thead>
          <tbody>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">One</td>
              <td class="text-left" rowspan="1" colspan="1">Forward</td>
              <td class="text-left" rowspan="1" colspan="1">0 s</td>
              <td class="text-left" rowspan="1" colspan="1">2.0</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">Two</td>
              <td class="text-left" rowspan="1" colspan="1">Forward</td>
              <td class="text-left" rowspan="1" colspan="1">25 s</td>
              <td class="text-left" rowspan="1" colspan="1">1.0</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">Three</td>
              <td class="text-left" rowspan="1" colspan="1">Forward</td>
              <td class="text-left" rowspan="1" colspan="1">50 s</td>
              <td class="text-left" rowspan="1" colspan="1">1.75</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">Four</td>
              <td class="text-left" rowspan="1" colspan="1">Forward</td>
              <td class="text-left" rowspan="1" colspan="1">75 s</td>
              <td class="text-left" rowspan="1" colspan="1">0.5</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">Five</td>
              <td class="text-left" rowspan="1" colspan="1">Forward</td>
              <td class="text-left" rowspan="1" colspan="1">100 s</td>
              <td class="text-left" rowspan="1" colspan="1">1.0</td>
            </tr>
          </tbody>
        </table>
</div>
</section>
</div>
<div id="CFL">
<section id="section-5.3">
        <h3 id="name-congested-feedback-link-wit">
<a href="#section-5.3" class="section-number selfRef">5.3. </a><a href="#name-congested-feedback-link-wit" class="section-name selfRef">Congested Feedback Link with Bi-directional Media Flows</a>
        </h3>
<p id="section-5.3-1">Real-time interactive media uses RTP; hence it is assumed that RTCP,
        RTP header extension, or such would be used by the congestion control
        algorithm in the back channel. Due to the asymmetric nature of the link
        between communicating peers, it is possible for a participating peer to
        not receive such feedback information due to an impaired or congested
        back channel (even when the forward channel might not be impaired).
        This test case is designed to observe the candidate congestion control
        behavior in such an event.<a href="#section-5.3-1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-5.3-2">
          <dt id="section-5.3-2.1">Expected behavior:</dt>
          <dd style="margin-left: 1.5em" id="section-5.3-2.2">
            <p id="section-5.3-2.2.1">It is expected that the candidate algorithms are
        able to cope with the lack of feedback information and to adapt to
        minimize the performance degradation of media flows in the forward
        channel.<a href="#section-5.3-2.2.1" class="pilcrow">¶</a></p>
<p id="section-5.3-2.2.2">It should be noted that for this test case, logs are compared with
        the reference case, i.e., when the backward channel has no
        impairments.<a href="#section-5.3-2.2.2" class="pilcrow">¶</a></p>
</dd>
          <dd class="break"></dd>
<dt id="section-5.3-2.3">Evaluation metrics:</dt>
          <dd style="margin-left: 1.5em" id="section-5.3-2.4">As described in <a href="#EM" class="xref">Section 4.1</a>.<a href="#section-5.3-2.4" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-5.3-2.5">Testbed topology:</dt>
          <dd style="margin-left: 1.5em" id="section-5.3-2.6">One (1) media source S1 is connected to
        corresponding R1, but both endpoints are additionally receiving and
        sending data, respectively. The media traffic (S1-&gt;R1) is
        transported over the forward path, and the corresponding feedback/control
        traffic is transported over the backward path. Likewise, media traffic
        (S2-&gt;R2) is transported over the backward path, and the corresponding
        feedback/control traffic is transported over the forward path.<a href="#section-5.3-2.6" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
</dl>
<span id="name-testbed-topology-for-conges"></span><div id="fig-eval-topo-4-6">
<figure id="figure-4">
          <div class="artwork art-text alignLeft" id="section-5.3-3.1">
<pre>
+---+                                                          +---+
|S1 |====== \                Forward --&gt;              / =======|R1 |
+---+       \\                                       //        +---+
             \\                                     //
          +-----+                               +-----+
          |  A  |------------------------------&gt;|  B  |
          |     |&lt;------------------------------|     |
          +-----+                               +-----+
             //                                     \\
            //            &lt;-- Backward               \\
+---+      //                                         \\       +---+
|R2 |===== /                                           \ ======|S2 |
+---+                                                          +---+
</pre>
</div>
<figcaption><a href="#figure-4" class="selfRef">Figure 4</a>:
<a href="#name-testbed-topology-for-conges" class="selfRef">Testbed Topology for Congested Feedback Link</a>
          </figcaption></figure>
</div>
<span class="break"></span><dl class="dlParallel" id="section-5.3-4">
          <dt id="section-5.3-4.1">Testbed attributes:</dt>
          <dd style="margin-left: 1.5em" id="section-5.3-4.2">
            <p id="section-5.3-4.2.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.3-4.2.2">
              <dt id="section-5.3-4.2.2.1">Test duration:</dt>
              <dd style="margin-left: 1.5em" id="section-5.3-4.2.2.2">100 s<a href="#section-5.3-4.2.2.2" class="pilcrow">¶</a>
</dd>
              <dd class="break"></dd>
<dt id="section-5.3-4.2.2.3">Path characteristics:</dt>
              <dd style="margin-left: 1.5em" id="section-5.3-4.2.2.4">
                <p id="section-5.3-4.2.2.4.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.3-4.2.2.4.2">
                  <dt id="section-5.3-4.2.2.4.2.1">Reference bottleneck capacity:</dt>
                  <dd style="margin-left: 1.5em" id="section-5.3-4.2.2.4.2.2">1 Mbps<a href="#section-5.3-4.2.2.4.2.2" class="pilcrow">¶</a>
</dd>
                <dd class="break"></dd>
</dl>
</dd>
              <dd class="break"></dd>
<dt id="section-5.3-4.2.2.5">Application-related:</dt>
              <dd style="margin-left: 1.5em" id="section-5.3-4.2.2.6">
                <p id="section-5.3-4.2.2.6.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.3-4.2.2.6.2">
                  <dt id="section-5.3-4.2.2.6.2.1">Media source:</dt>
                  <dd style="margin-left: 1.5em" id="section-5.3-4.2.2.6.2.2">
                    <p id="section-5.3-4.2.2.6.2.2.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.3-4.2.2.6.2.2.2">
                      <dt id="section-5.3-4.2.2.6.2.2.2.1">Media type:</dt>
                      <dd style="margin-left: 1.5em" id="section-5.3-4.2.2.6.2.2.2.2">
                        <p id="section-5.3-4.2.2.6.2.2.2.2.1">Video<a href="#section-5.3-4.2.2.6.2.2.2.2.1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-5.3-4.2.2.6.2.2.2.2.2">
                          <dt id="section-5.3-4.2.2.6.2.2.2.2.2.1">Media direction:</dt>
                          <dd style="margin-left: 1.5em" id="section-5.3-4.2.2.6.2.2.2.2.2.2">forward and backward<a href="#section-5.3-4.2.2.6.2.2.2.2.2.2" class="pilcrow">¶</a>
</dd>
                          <dd class="break"></dd>
<dt id="section-5.3-4.2.2.6.2.2.2.2.2.3">Number of media sources:</dt>
                          <dd style="margin-left: 1.5em" id="section-5.3-4.2.2.6.2.2.2.2.2.4">two (2)<a href="#section-5.3-4.2.2.6.2.2.2.2.2.4" class="pilcrow">¶</a>
</dd>
                          <dd class="break"></dd>
<dt id="section-5.3-4.2.2.6.2.2.2.2.2.5">Media timeline:</dt>
                          <dd style="margin-left: 1.5em" id="section-5.3-4.2.2.6.2.2.2.2.2.6">
                            <p id="section-5.3-4.2.2.6.2.2.2.2.2.6.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.3-4.2.2.6.2.2.2.2.2.6.2">
                              <dt id="section-5.3-4.2.2.6.2.2.2.2.2.6.2.1">Start time:</dt>
                              <dd style="margin-left: 1.5em" id="section-5.3-4.2.2.6.2.2.2.2.2.6.2.2">0 s<a href="#section-5.3-4.2.2.6.2.2.2.2.2.6.2.2" class="pilcrow">¶</a>
</dd>
                              <dd class="break"></dd>
<dt id="section-5.3-4.2.2.6.2.2.2.2.2.6.2.3">End time:</dt>
                              <dd style="margin-left: 1.5em" id="section-5.3-4.2.2.6.2.2.2.2.2.6.2.4">99 s<a href="#section-5.3-4.2.2.6.2.2.2.2.2.6.2.4" class="pilcrow">¶</a>
</dd>
                            <dd class="break"></dd>
</dl>
</dd>
                        <dd class="break"></dd>
</dl>
</dd>
                      <dd class="break"></dd>
<dt id="section-5.3-4.2.2.6.2.2.2.3">Media type:</dt>
                      <dd style="margin-left: 1.5em" id="section-5.3-4.2.2.6.2.2.2.4">
                        <p id="section-5.3-4.2.2.6.2.2.2.4.1">Audio<a href="#section-5.3-4.2.2.6.2.2.2.4.1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-5.3-4.2.2.6.2.2.2.4.2">
                          <dt id="section-5.3-4.2.2.6.2.2.2.4.2.1">Media direction:</dt>
                          <dd style="margin-left: 1.5em" id="section-5.3-4.2.2.6.2.2.2.4.2.2">forward and backward<a href="#section-5.3-4.2.2.6.2.2.2.4.2.2" class="pilcrow">¶</a>
</dd>
                          <dd class="break"></dd>
<dt id="section-5.3-4.2.2.6.2.2.2.4.2.3">Number of media sources:</dt>
                          <dd style="margin-left: 1.5em" id="section-5.3-4.2.2.6.2.2.2.4.2.4">two (2)<a href="#section-5.3-4.2.2.6.2.2.2.4.2.4" class="pilcrow">¶</a>
</dd>
                          <dd class="break"></dd>
<dt id="section-5.3-4.2.2.6.2.2.2.4.2.5">Media timeline: </dt>
                          <dd style="margin-left: 1.5em" id="section-5.3-4.2.2.6.2.2.2.4.2.6">
                            <p id="section-5.3-4.2.2.6.2.2.2.4.2.6.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.3-4.2.2.6.2.2.2.4.2.6.2">
                              <dt id="section-5.3-4.2.2.6.2.2.2.4.2.6.2.1">Start time:</dt>
                              <dd style="margin-left: 1.5em" id="section-5.3-4.2.2.6.2.2.2.4.2.6.2.2">0 s<a href="#section-5.3-4.2.2.6.2.2.2.4.2.6.2.2" class="pilcrow">¶</a>
</dd>
                              <dd class="break"></dd>
<dt id="section-5.3-4.2.2.6.2.2.2.4.2.6.2.3">End time:</dt>
                              <dd style="margin-left: 1.5em" id="section-5.3-4.2.2.6.2.2.2.4.2.6.2.4">99 s<a href="#section-5.3-4.2.2.6.2.2.2.4.2.6.2.4" class="pilcrow">¶</a>
</dd>
                            <dd class="break"></dd>
</dl>
</dd>
                        <dd class="break"></dd>
</dl>
</dd>
                    <dd class="break"></dd>
</dl>
</dd>
                  <dd class="break"></dd>
<dt id="section-5.3-4.2.2.6.2.3">Competing traffic: </dt>
                  <dd style="margin-left: 1.5em" id="section-5.3-4.2.2.6.2.4">
                    <p id="section-5.3-4.2.2.6.2.4.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.3-4.2.2.6.2.4.2">
                      <dt id="section-5.3-4.2.2.6.2.4.2.1">Number of sources:</dt>
                      <dd style="margin-left: 1.5em" id="section-5.3-4.2.2.6.2.4.2.2">zero (0)<a href="#section-5.3-4.2.2.6.2.4.2.2" class="pilcrow">¶</a>
</dd>
                    <dd class="break"></dd>
</dl>
</dd>
                <dd class="break"></dd>
</dl>
</dd>
            <dd class="break"></dd>
</dl>
</dd>
          <dd class="break"></dd>
<dt id="section-5.3-4.3">Test-specific information:</dt>
          <dd style="margin-left: 1.5em" id="section-5.3-4.4">This test uses path capacity
            variations to create a congested feedback link. <a href="#CFL_US" class="xref">Table 3</a> 
            lists the variation patterns applied to
            the forward path, and <a href="#CFL_DS" class="xref">Table 4</a> lists the variation
            patterns applied to the backward path. When using background
            non-adaptive UDP traffic to induce a time-varying bottleneck for
            congestion-controlled media flows, the physical path capacity is
            4 Mbps for both directions, and the UDP traffic source rate changes
            over time as (4-x) Mbps in each direction, where x is the
            bottleneck capacity specified in <a href="#CFL_DS" class="xref">Table 4</a>.<a href="#section-5.3-4.4" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
</dl>
<span id="name-path-capacity-variation-patte"></span><div id="CFL_US">
<table class="center" id="table-3">
          <caption>
<a href="#table-3" class="selfRef">Table 3</a>:
<a href="#name-path-capacity-variation-patte" class="selfRef">Path Capacity Variation Pattern for the Forward Direction</a>
          </caption>
<thead>
            <tr>
              <th class="text-left" rowspan="1" colspan="1">Variation pattern index</th>
              <th class="text-left" rowspan="1" colspan="1">Path direction</th>
              <th class="text-left" rowspan="1" colspan="1">Start time</th>
              <th class="text-left" rowspan="1" colspan="1">Path capacity ratio</th>
            </tr>
          </thead>
          <tbody>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">One</td>
              <td class="text-left" rowspan="1" colspan="1">Forward</td>
              <td class="text-left" rowspan="1" colspan="1">0 s</td>
              <td class="text-left" rowspan="1" colspan="1">2.0</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">Two</td>
              <td class="text-left" rowspan="1" colspan="1">Forward</td>
              <td class="text-left" rowspan="1" colspan="1">20 s</td>
              <td class="text-left" rowspan="1" colspan="1">1.0</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">Three</td>
              <td class="text-left" rowspan="1" colspan="1">Forward</td>
              <td class="text-left" rowspan="1" colspan="1">40 s</td>
              <td class="text-left" rowspan="1" colspan="1">0.5</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">Four</td>
              <td class="text-left" rowspan="1" colspan="1">Forward</td>
              <td class="text-left" rowspan="1" colspan="1">60 s</td>
              <td class="text-left" rowspan="1" colspan="1">2.0</td>
            </tr>
          </tbody>
        </table>
</div>
<p id="section-5.3-6"></p>
<span id="name-path-capacity-variation-patter"></span><div id="CFL_DS">
<table class="center" id="table-4">
          <caption>
<a href="#table-4" class="selfRef">Table 4</a>:
<a href="#name-path-capacity-variation-patter" class="selfRef">Path Capacity Variation Pattern for the Backward Direction</a>
          </caption>
<thead>
            <tr>
              <th class="text-left" rowspan="1" colspan="1">Variation pattern index</th>
              <th class="text-left" rowspan="1" colspan="1">Path direction</th>
              <th class="text-left" rowspan="1" colspan="1">Start time</th>
              <th class="text-left" rowspan="1" colspan="1">Path capacity ratio</th>
            </tr>
          </thead>
          <tbody>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">One</td>
              <td class="text-left" rowspan="1" colspan="1">Backward</td>
              <td class="text-left" rowspan="1" colspan="1">0 s</td>
              <td class="text-left" rowspan="1" colspan="1">2.0</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">Two</td>
              <td class="text-left" rowspan="1" colspan="1">Backward</td>
              <td class="text-left" rowspan="1" colspan="1">35 s</td>
              <td class="text-left" rowspan="1" colspan="1">0.8</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">Three</td>
              <td class="text-left" rowspan="1" colspan="1">Backward</td>
              <td class="text-left" rowspan="1" colspan="1">70 s</td>
              <td class="text-left" rowspan="1" colspan="1">2.0</td>
            </tr>
          </tbody>
        </table>
</div>
</section>
</div>
<div id="competing-rmcat-flow">
<section id="section-5.4">
        <h3 id="name-competing-media-flows-with-">
<a href="#section-5.4" class="section-number selfRef">5.4. </a><a href="#name-competing-media-flows-with-" class="section-name selfRef">Competing Media Flows with the Same Congestion Control Algorithm</a>
        </h3>
<p id="section-5.4-1">In this test case, more than one media flow share the bottleneck
        link, and each of them uses the same congestion control algorithm. This
        is a typical scenario where a real-time interactive application sends
        more than one media flow to the same destination, and these flows are
        multiplexed over the same port. In such a scenario, it is likely that
        the flows will be routed via the same path and need to share the
        available bandwidth amongst themselves. For the sake of simplicity, it
        is assumed that there are no other competing traffic sources in the
        bottleneck link and that there is sufficient capacity to accommodate
        all the flows individually. While this appears to be a variant of the
        test case defined in <a href="#VACM" class="xref">Section 5.2</a>, it focuses 
        on the capacity-sharing aspect of the candidate algorithm. The previous test case, on
        the other hand, measures adaptability, stability, and responsiveness
        of the candidate algorithm.<a href="#section-5.4-1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-5.4-2">
          <dt id="section-5.4-2.1">Expected behavior:</dt>
          <dd style="margin-left: 1.5em" id="section-5.4-2.2">It is expected that the competing flows will
        converge to an optimum bit rate to accommodate all the flows with
        minimum possible latency and loss. Specifically, the test introduces
        three media flows at different time instances. When the second flow
        appears, there should still be room to accommodate another flow on the
        bottleneck link. Lastly, when the third flow appears, the bottleneck
        link should be saturated.<a href="#section-5.4-2.2" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-5.4-2.3">Evaluation metrics:</dt>
          <dd style="margin-left: 1.5em" id="section-5.4-2.4">As described in <a href="#EM" class="xref">Section 4.1</a>.<a href="#section-5.4-2.4" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-5.4-2.5">Testbed topology: </dt>
          <dd style="margin-left: 1.5em" id="section-5.4-2.6">Three media sources S1, S2, and S3 are connected to
        R1, R2, and R3, respectively. The media traffic is transported over the
        forward path, and the corresponding feedback/control traffic is transported
        over the backward path.<a href="#section-5.4-2.6" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
</dl>
<span id="name-testbed-topology-for-multip"></span><div id="fig-eval-topo-4-3">
<figure id="figure-5">
          <div class="artwork art-text alignLeft" id="section-5.4-3.1">
<pre>
+---+                                                         +---+
|S1 |===== \                Forward --&gt;              / =======|R1 |
+---+      \\                                       //        +---+
            \\                                     //
+---+       +-----+                               +-----+       +---+
|S2 |=======|  A  |------------------------------&gt;|  B  |=======|R2 |
+---+       |     |&lt;------------------------------|     |       +---+
            +-----+                               +-----+
            //          &lt;-- Backward               \\
+---+      //                                       \\       +---+
|S3 |===== /                                         \ ======|R3 |
+---+                                                        +---+
</pre>
</div>
<figcaption><a href="#figure-5" class="selfRef">Figure 5</a>:
<a href="#name-testbed-topology-for-multip" class="selfRef">Testbed Topology for Multiple Congestion-Controlled Media Flows</a>
          </figcaption></figure>
</div>
<span class="break"></span><dl class="dlParallel" id="section-5.4-4">
          <dt id="section-5.4-4.1">Testbed attributes:</dt>
          <dd style="margin-left: 1.5em" id="section-5.4-4.2">
            <p id="section-5.4-4.2.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.4-4.2.2">
              <dt id="section-5.4-4.2.2.1">Test duration:</dt>
              <dd style="margin-left: 1.5em" id="section-5.4-4.2.2.2">120 s<a href="#section-5.4-4.2.2.2" class="pilcrow">¶</a>
</dd>
              <dd class="break"></dd>
<dt id="section-5.4-4.2.2.3">Path characteristics:</dt>
              <dd style="margin-left: 1.5em" id="section-5.4-4.2.2.4">
                <p id="section-5.4-4.2.2.4.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.4-4.2.2.4.2">
                  <dt id="section-5.4-4.2.2.4.2.1">Reference bottleneck capacity:</dt>
                  <dd style="margin-left: 1.5em" id="section-5.4-4.2.2.4.2.2">3.5 Mbps<a href="#section-5.4-4.2.2.4.2.2" class="pilcrow">¶</a>
</dd>
                  <dd class="break"></dd>
<dt id="section-5.4-4.2.2.4.2.3">Path capacity ratio:</dt>
                  <dd style="margin-left: 1.5em" id="section-5.4-4.2.2.4.2.4">1.0<a href="#section-5.4-4.2.2.4.2.4" class="pilcrow">¶</a>
</dd>
                <dd class="break"></dd>
</dl>
</dd>
              <dd class="break"></dd>
<dt id="section-5.4-4.2.2.5">Application-related: </dt>
              <dd style="margin-left: 1.5em" id="section-5.4-4.2.2.6">
                <p id="section-5.4-4.2.2.6.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.4-4.2.2.6.2">
                  <dt id="section-5.4-4.2.2.6.2.1">Media Source: </dt>
                  <dd style="margin-left: 1.5em" id="section-5.4-4.2.2.6.2.2">
                    <p id="section-5.4-4.2.2.6.2.2.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.4-4.2.2.6.2.2.2">
                      <dt id="section-5.4-4.2.2.6.2.2.2.1">Media type:</dt>
                      <dd style="margin-left: 1.5em" id="section-5.4-4.2.2.6.2.2.2.2">
                        <p id="section-5.4-4.2.2.6.2.2.2.2.1">Video<a href="#section-5.4-4.2.2.6.2.2.2.2.1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-5.4-4.2.2.6.2.2.2.2.2">
                          <dt id="section-5.4-4.2.2.6.2.2.2.2.2.1">Media direction:</dt>
                          <dd style="margin-left: 1.5em" id="section-5.4-4.2.2.6.2.2.2.2.2.2">forward<a href="#section-5.4-4.2.2.6.2.2.2.2.2.2" class="pilcrow">¶</a>
</dd>
                          <dd class="break"></dd>
<dt id="section-5.4-4.2.2.6.2.2.2.2.2.3">Number of media sources:</dt>
                          <dd style="margin-left: 1.5em" id="section-5.4-4.2.2.6.2.2.2.2.2.4">three (3)<a href="#section-5.4-4.2.2.6.2.2.2.2.2.4" class="pilcrow">¶</a>
</dd>
                          <dd class="break"></dd>
<dt id="section-5.4-4.2.2.6.2.2.2.2.2.5">Media timeline:</dt>
                          <dd style="margin-left: 1.5em" id="section-5.4-4.2.2.6.2.2.2.2.2.6">New media flows are added
                        sequentially, at short time intervals. See the 
                        test-specific setup below.<a href="#section-5.4-4.2.2.6.2.2.2.2.2.6" class="pilcrow">¶</a>
</dd>
                        <dd class="break"></dd>
</dl>
</dd>
                      <dd class="break"></dd>
<dt id="section-5.4-4.2.2.6.2.2.2.3">Media type:</dt>
                      <dd style="margin-left: 1.5em" id="section-5.4-4.2.2.6.2.2.2.4">
                        <p id="section-5.4-4.2.2.6.2.2.2.4.1">Audio<a href="#section-5.4-4.2.2.6.2.2.2.4.1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-5.4-4.2.2.6.2.2.2.4.2">
                          <dt id="section-5.4-4.2.2.6.2.2.2.4.2.1">Media direction:</dt>
                          <dd style="margin-left: 1.5em" id="section-5.4-4.2.2.6.2.2.2.4.2.2">forward<a href="#section-5.4-4.2.2.6.2.2.2.4.2.2" class="pilcrow">¶</a>
</dd>
                          <dd class="break"></dd>
<dt id="section-5.4-4.2.2.6.2.2.2.4.2.3">Number of media sources:</dt>
                          <dd style="margin-left: 1.5em" id="section-5.4-4.2.2.6.2.2.2.4.2.4">three (3)<a href="#section-5.4-4.2.2.6.2.2.2.4.2.4" class="pilcrow">¶</a>
</dd>
                          <dd class="break"></dd>
<dt id="section-5.4-4.2.2.6.2.2.2.4.2.5">Media timeline:</dt>
                          <dd style="margin-left: 1.5em" id="section-5.4-4.2.2.6.2.2.2.4.2.6">New media flows are added
                        sequentially, at short time intervals. See the test-specific setup below.<a href="#section-5.4-4.2.2.6.2.2.2.4.2.6" class="pilcrow">¶</a>
</dd>
                        <dd class="break"></dd>
</dl>
</dd>
                    <dd class="break"></dd>
</dl>
</dd>
                  <dd class="break"></dd>
<dt id="section-5.4-4.2.2.6.2.3">Competing traffic: </dt>
                  <dd style="margin-left: 1.5em" id="section-5.4-4.2.2.6.2.4">
                    <p id="section-5.4-4.2.2.6.2.4.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.4-4.2.2.6.2.4.2">
                      <dt id="section-5.4-4.2.2.6.2.4.2.1">Number of sources:</dt>
                      <dd style="margin-left: 1.5em" id="section-5.4-4.2.2.6.2.4.2.2">zero (0)<a href="#section-5.4-4.2.2.6.2.4.2.2" class="pilcrow">¶</a>
</dd>
                    <dd class="break"></dd>
</dl>
</dd>
                <dd class="break"></dd>
</dl>
</dd>
            <dd class="break"></dd>
</dl>
</dd>
          <dd class="break"></dd>
<dt id="section-5.4-4.3">Test-specific information:</dt>
          <dd style="margin-left: 1.5em" id="section-5.4-4.4">
            <a href="#MTL_CF" class="xref">Table 5</a> defines the
            media timeline for both media types.<a href="#section-5.4-4.4" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
</dl>
<span id="name-media-timelines-for-video-a"></span><div id="MTL_CF">
<table class="center" id="table-5">
          <caption>
<a href="#table-5" class="selfRef">Table 5</a>:
<a href="#name-media-timelines-for-video-a" class="selfRef">Media Timelines for Video and Audio Media Sources</a>
          </caption>
<thead>
            <tr>
              <th class="text-left" rowspan="1" colspan="1">Flow ID</th>
              <th class="text-left" rowspan="1" colspan="1">Media type</th>
              <th class="text-left" rowspan="1" colspan="1">Start time</th>
              <th class="text-left" rowspan="1" colspan="1">End time</th>
            </tr>
          </thead>
          <tbody>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">1</td>
              <td class="text-left" rowspan="1" colspan="1">Video</td>
              <td class="text-left" rowspan="1" colspan="1">0 s</td>
              <td class="text-left" rowspan="1" colspan="1">119 s</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">2</td>
              <td class="text-left" rowspan="1" colspan="1">Video</td>
              <td class="text-left" rowspan="1" colspan="1">20 s</td>
              <td class="text-left" rowspan="1" colspan="1">119 s</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">3</td>
              <td class="text-left" rowspan="1" colspan="1">Video</td>
              <td class="text-left" rowspan="1" colspan="1">40 s</td>
              <td class="text-left" rowspan="1" colspan="1">119 s</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">4</td>
              <td class="text-left" rowspan="1" colspan="1">Audio</td>
              <td class="text-left" rowspan="1" colspan="1">0 s</td>
              <td class="text-left" rowspan="1" colspan="1">119 s</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">5</td>
              <td class="text-left" rowspan="1" colspan="1">Audio</td>
              <td class="text-left" rowspan="1" colspan="1">20 s</td>
              <td class="text-left" rowspan="1" colspan="1">119 s</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">6</td>
              <td class="text-left" rowspan="1" colspan="1">Audio</td>
              <td class="text-left" rowspan="1" colspan="1">40 s</td>
              <td class="text-left" rowspan="1" colspan="1">119 s</td>
            </tr>
          </tbody>
        </table>
</div>
</section>
</div>
<section id="section-5.5">
        <h3 id="name-round-trip-time-fairness">
<a href="#section-5.5" class="section-number selfRef">5.5. </a><a href="#name-round-trip-time-fairness" class="section-name selfRef">Round Trip Time Fairness</a>
        </h3>
<p id="section-5.5-1">In this test case, multiple media flows share the bottleneck link,
        but the one-way propagation delay for each flow is different. For the
        sake of simplicity, it is assumed that there are no other competing
        traffic sources in the bottleneck link and that there is sufficient
        capacity to accommodate all the flows. While this appears to be a
        variant of test case 5.2 (<a href="#VACM" class="xref">Section 5.2</a>), 
        it focuses on the capacity-sharing aspect of
        the candidate algorithm under different RTTs.<a href="#section-5.5-1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-5.5-2">
          <dt id="section-5.5-2.1">Expected behavior:</dt>
          <dd style="margin-left: 1.5em" id="section-5.5-2.2">It is expected that the competing flows will
        converge to bit rates to accommodate all the flows with minimum
        possible latency and loss. The effectiveness of the algorithm depends
        on how fast and fairly the competing flows converge to their steady
        states irrespective of the RTT observed.<a href="#section-5.5-2.2" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-5.5-2.3">Evaluation metrics:</dt>
          <dd style="margin-left: 1.5em" id="section-5.5-2.4">As described in <a href="#EM" class="xref">Section 4.1</a>.<a href="#section-5.5-2.4" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-5.5-2.5">Testbed topology: </dt>
          <dd style="margin-left: 1.5em" id="section-5.5-2.6">Five (5) media sources S1..S5 are connected
        to their corresponding media sinks R1..R5. The media traffic is
        transported over the forward path, and the corresponding feedback/control
        traffic is transported over the backward path. The topology is the
        same as in <a href="#competing-rmcat-flow" class="xref">Section 5.4</a>.<a href="#section-5.5-2.6" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-5.5-2.7">Testbed attributes: </dt>
          <dd style="margin-left: 1.5em" id="section-5.5-2.8">
            <p id="section-5.5-2.8.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.5-2.8.2">
              <dt id="section-5.5-2.8.2.1">Test duration:</dt>
              <dd style="margin-left: 1.5em" id="section-5.5-2.8.2.2">300 s<a href="#section-5.5-2.8.2.2" class="pilcrow">¶</a>
</dd>
              <dd class="break"></dd>
<dt id="section-5.5-2.8.2.3">Path characteristics: </dt>
              <dd style="margin-left: 1.5em" id="section-5.5-2.8.2.4">
                <p id="section-5.5-2.8.2.4.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.5-2.8.2.4.2">
                  <dt id="section-5.5-2.8.2.4.2.1">Reference bottleneck capacity:</dt>
                  <dd style="margin-left: 1.5em" id="section-5.5-2.8.2.4.2.2">4 Mbps<a href="#section-5.5-2.8.2.4.2.2" class="pilcrow">¶</a>
</dd>
                  <dd class="break"></dd>
<dt id="section-5.5-2.8.2.4.2.3">Path capacity ratio:</dt>
                  <dd style="margin-left: 1.5em" id="section-5.5-2.8.2.4.2.4">1.0<a href="#section-5.5-2.8.2.4.2.4" class="pilcrow">¶</a>
</dd>
                  <dd class="break"></dd>
<dt id="section-5.5-2.8.2.4.2.5">One-way propagation delay for each flow:</dt>
                  <dd style="margin-left: 1.5em" id="section-5.5-2.8.2.4.2.6">10 ms for S1-R1,
                25 ms for S2-R2, 50 ms for S3-R3, 100 ms for S4-R4, and 150 ms
                S5-R5.<a href="#section-5.5-2.8.2.4.2.6" class="pilcrow">¶</a>
</dd>
                <dd class="break"></dd>
</dl>
</dd>
              <dd class="break"></dd>
<dt id="section-5.5-2.8.2.5">Application-related: </dt>
              <dd style="margin-left: 1.5em" id="section-5.5-2.8.2.6">
                <p id="section-5.5-2.8.2.6.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.5-2.8.2.6.2">
                  <dt id="section-5.5-2.8.2.6.2.1">Media source: </dt>
                  <dd style="margin-left: 1.5em" id="section-5.5-2.8.2.6.2.2">
                    <p id="section-5.5-2.8.2.6.2.2.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.5-2.8.2.6.2.2.2">
                      <dt id="section-5.5-2.8.2.6.2.2.2.1">Media type:</dt>
                      <dd style="margin-left: 1.5em" id="section-5.5-2.8.2.6.2.2.2.2">
                        <p id="section-5.5-2.8.2.6.2.2.2.2.1">Video<a href="#section-5.5-2.8.2.6.2.2.2.2.1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-5.5-2.8.2.6.2.2.2.2.2">
                          <dt id="section-5.5-2.8.2.6.2.2.2.2.2.1">Media direction:</dt>
                          <dd style="margin-left: 1.5em" id="section-5.5-2.8.2.6.2.2.2.2.2.2">forward<a href="#section-5.5-2.8.2.6.2.2.2.2.2.2" class="pilcrow">¶</a>
</dd>
                          <dd class="break"></dd>
<dt id="section-5.5-2.8.2.6.2.2.2.2.2.3">Number of media sources:</dt>
                          <dd style="margin-left: 1.5em" id="section-5.5-2.8.2.6.2.2.2.2.2.4">five (5)<a href="#section-5.5-2.8.2.6.2.2.2.2.2.4" class="pilcrow">¶</a>
</dd>
                          <dd class="break"></dd>
<dt id="section-5.5-2.8.2.6.2.2.2.2.2.5">Media timeline:</dt>
                          <dd style="margin-left: 1.5em" id="section-5.5-2.8.2.6.2.2.2.2.2.6">New media flows are added
                        sequentially, at short time intervals. See the 
                        test-specific setup below.<a href="#section-5.5-2.8.2.6.2.2.2.2.2.6" class="pilcrow">¶</a>
</dd>
                        <dd class="break"></dd>
</dl>
</dd>
                      <dd class="break"></dd>
<dt id="section-5.5-2.8.2.6.2.2.2.3">Media type:</dt>
                      <dd style="margin-left: 1.5em" id="section-5.5-2.8.2.6.2.2.2.4">
                        <p id="section-5.5-2.8.2.6.2.2.2.4.1">Audio<a href="#section-5.5-2.8.2.6.2.2.2.4.1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-5.5-2.8.2.6.2.2.2.4.2">
                          <dt id="section-5.5-2.8.2.6.2.2.2.4.2.1">Media direction:</dt>
                          <dd style="margin-left: 1.5em" id="section-5.5-2.8.2.6.2.2.2.4.2.2">forward<a href="#section-5.5-2.8.2.6.2.2.2.4.2.2" class="pilcrow">¶</a>
</dd>
                          <dd class="break"></dd>
<dt id="section-5.5-2.8.2.6.2.2.2.4.2.3">Number of media sources:</dt>
                          <dd style="margin-left: 1.5em" id="section-5.5-2.8.2.6.2.2.2.4.2.4"> five (5)<a href="#section-5.5-2.8.2.6.2.2.2.4.2.4" class="pilcrow">¶</a>
</dd>
                          <dd class="break"></dd>
<dt id="section-5.5-2.8.2.6.2.2.2.4.2.5">Media timeline:</dt>
                          <dd style="margin-left: 1.5em" id="section-5.5-2.8.2.6.2.2.2.4.2.6">New media flows are added
                        sequentially, at short time intervals. See the
                        test-specific setup below.<a href="#section-5.5-2.8.2.6.2.2.2.4.2.6" class="pilcrow">¶</a>
</dd>
                        <dd class="break"></dd>
</dl>
</dd>
                    <dd class="break"></dd>
</dl>
</dd>
                  <dd class="break"></dd>
<dt id="section-5.5-2.8.2.6.2.3">Competing traffic: </dt>
                  <dd style="margin-left: 1.5em" id="section-5.5-2.8.2.6.2.4">
                    <p id="section-5.5-2.8.2.6.2.4.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.5-2.8.2.6.2.4.2">
                      <dt id="section-5.5-2.8.2.6.2.4.2.1">Number of sources:</dt>
                      <dd style="margin-left: 1.5em" id="section-5.5-2.8.2.6.2.4.2.2">zero (0)<a href="#section-5.5-2.8.2.6.2.4.2.2" class="pilcrow">¶</a>
</dd>
                    <dd class="break"></dd>
</dl>
</dd>
                <dd class="break"></dd>
</dl>
</dd>
            <dd class="break"></dd>
</dl>
</dd>
          <dd class="break"></dd>
<dt id="section-5.5-2.9">Test-specific information: </dt>
          <dd style="margin-left: 1.5em" id="section-5.5-2.10">
            <a href="#MTL_RTT" class="xref">Table 6</a> defines the
            media timeline for both media types.<a href="#section-5.5-2.10" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
</dl>
<span id="name-media-timeline-for-video-an"></span><div id="MTL_RTT">
<table class="center" id="table-6">
          <caption>
<a href="#table-6" class="selfRef">Table 6</a>:
<a href="#name-media-timeline-for-video-an" class="selfRef">Media Timeline for Video and Audio Media Sources</a>
          </caption>
<thead>
            <tr>
              <th class="text-left" rowspan="1" colspan="1">Flow ID</th>
              <th class="text-left" rowspan="1" colspan="1">Media type</th>
              <th class="text-left" rowspan="1" colspan="1">Start time</th>
              <th class="text-left" rowspan="1" colspan="1">End time</th>
            </tr>
          </thead>
          <tbody>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">1</td>
              <td class="text-left" rowspan="1" colspan="1">Video</td>
              <td class="text-left" rowspan="1" colspan="1">0 s</td>
              <td class="text-left" rowspan="1" colspan="1">299 s</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">2</td>
              <td class="text-left" rowspan="1" colspan="1">Video</td>
              <td class="text-left" rowspan="1" colspan="1">10 s</td>
              <td class="text-left" rowspan="1" colspan="1">299 s</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">3</td>
              <td class="text-left" rowspan="1" colspan="1">Video</td>
              <td class="text-left" rowspan="1" colspan="1">20 s</td>
              <td class="text-left" rowspan="1" colspan="1">299 s</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">4</td>
              <td class="text-left" rowspan="1" colspan="1">Video</td>
              <td class="text-left" rowspan="1" colspan="1">30 s</td>
              <td class="text-left" rowspan="1" colspan="1">299 s</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">5</td>
              <td class="text-left" rowspan="1" colspan="1">Video</td>
              <td class="text-left" rowspan="1" colspan="1">40 s</td>
              <td class="text-left" rowspan="1" colspan="1">299 s</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">6</td>
              <td class="text-left" rowspan="1" colspan="1">Audio</td>
              <td class="text-left" rowspan="1" colspan="1">0 s</td>
              <td class="text-left" rowspan="1" colspan="1">299 s</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">7</td>
              <td class="text-left" rowspan="1" colspan="1">Audio</td>
              <td class="text-left" rowspan="1" colspan="1">10 s</td>
              <td class="text-left" rowspan="1" colspan="1">299 s</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">8</td>
              <td class="text-left" rowspan="1" colspan="1">Audio</td>
              <td class="text-left" rowspan="1" colspan="1">20 s</td>
              <td class="text-left" rowspan="1" colspan="1">299 s</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">9</td>
              <td class="text-left" rowspan="1" colspan="1">Audio</td>
              <td class="text-left" rowspan="1" colspan="1">30 s</td>
              <td class="text-left" rowspan="1" colspan="1">299 s</td>
            </tr>
            <tr>
              <td class="text-left" rowspan="1" colspan="1">10</td>
              <td class="text-left" rowspan="1" colspan="1">Audio</td>
              <td class="text-left" rowspan="1" colspan="1">40 s</td>
              <td class="text-left" rowspan="1" colspan="1">299 s</td>
            </tr>
          </tbody>
        </table>
</div>
</section>
<section id="section-5.6">
        <h3 id="name-media-flow-competing-with-a">
<a href="#section-5.6" class="section-number selfRef">5.6. </a><a href="#name-media-flow-competing-with-a" class="section-name selfRef">Media Flow Competing with a Long TCP Flow</a>
        </h3>
<p id="section-5.6-1">In this test case, one or more media flows share the bottleneck
        link with at least one long-lived TCP flow. Long-lived TCP flows
        download data throughout the session and are expected to have infinite
        amount of data to send and receive. This is a scenario where a
        multimedia application coexists with a large file download. The test
        case measures the adaptivity of the candidate algorithm to competing
        traffic. It addresses requirement 3 in <span><a href="https://www.rfc-editor.org/rfc/rfc8836#section-2" class="relref">Section 2</a> of [<a href="#RFC8836" class="xref">RFC8836</a>]</span>.<a href="#section-5.6-1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-5.6-2">
          <dt id="section-5.6-2.1">Expected behavior:</dt>
          <dd style="margin-left: 1.5em" id="section-5.6-2.2">Depending on the convergence observed in test
        cases 5.1 and 5.2, the candidate algorithm may be able to avoid
        congestion collapse. In the worst case, the media stream will fall to
        the minimum media bit rate.<a href="#section-5.6-2.2" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-5.6-2.3">Evaluation metrics:</dt>
          <dd style="margin-left: 1.5em" id="section-5.6-2.4">
            <p id="section-5.6-2.4.1">Includes the following metrics in addition to those described
        in <a href="#EM" class="xref">Section 4.1</a>:<a href="#section-5.6-2.4.1" class="pilcrow">¶</a></p>
<ol start="1" type="1" class="normal type-1" id="section-5.6-2.4.2">
              <li id="section-5.6-2.4.2.1">
                <p id="section-5.6-2.4.2.1.1">Flow level:<a href="#section-5.6-2.4.2.1.1" class="pilcrow">¶</a></p>
<ol start="1" type="a" class="normal type-a" id="section-5.6-2.4.2.1.2">
                   <li id="section-5.6-2.4.2.1.2.1">TCP throughput<a href="#section-5.6-2.4.2.1.2.1" class="pilcrow">¶</a>
</li>
                  <li id="section-5.6-2.4.2.1.2.2">Loss for the TCP flow<a href="#section-5.6-2.4.2.1.2.2" class="pilcrow">¶</a>
</li>
                </ol>
</li>
            </ol>
</dd>
          <dd class="break"></dd>
<dt id="section-5.6-2.5">Testbed topology:</dt>
          <dd style="margin-left: 1.5em" id="section-5.6-2.6">One (1) media source S1 is connected to the
        corresponding media sink, R1. In addition, there is a long-lived TCP
        flow sharing the same bottleneck link. The media traffic is
        transported over the forward path, and the corresponding feedback/control
        traffic is transported over the backward path. The TCP traffic goes
        over the forward path from S_tcp with acknowledgment packets going over
        the backward path from R_tcp.<a href="#section-5.6-2.6" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
</dl>
<span id="name-testbed-topology-for-tcp-vs"></span><div id="fig-eval-topo-4-4">
<figure id="figure-6">
          <div class="artwork art-text alignLeft" id="section-5.6-3.1">
<pre>
 +--+                                                     +--+
 |S1|===== \              Forward --&gt;              / =====|R1|
 +--+      \\                                     //      +--+
            \\                                   //
            +-----+                             +-----+
            |  A  |----------------------------&gt;|  B  |
            |     |&lt;----------------------------|     |
            +-----+                             +-----+
            //        &lt;-- Backward               \\
+-----+    //                                     \\    +-----+
|S_tcp|=== /                                       \ ===|R_tcp|
+-----+                                                 +-----+
</pre>
</div>
<figcaption><a href="#figure-6" class="selfRef">Figure 6</a>:
<a href="#name-testbed-topology-for-tcp-vs" class="selfRef">Testbed Topology for TCP vs Congestion-Controlled Media Flows</a>
          </figcaption></figure>
</div>
<span class="break"></span><dl class="dlParallel" id="section-5.6-4">
          <dt id="section-5.6-4.1">Testbed attributes:</dt>
          <dd style="margin-left: 1.5em" id="section-5.6-4.2">
            <p id="section-5.6-4.2.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.6-4.2.2">
              <dt id="section-5.6-4.2.2.1">Test duration:</dt>
              <dd style="margin-left: 1.5em" id="section-5.6-4.2.2.2">120 s<a href="#section-5.6-4.2.2.2" class="pilcrow">¶</a>
</dd>
              <dd class="break"></dd>
<dt id="section-5.6-4.2.2.3">Path characteristics:</dt>
              <dd style="margin-left: 1.5em" id="section-5.6-4.2.2.4">
                <p id="section-5.6-4.2.2.4.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.6-4.2.2.4.2">
                  <dt id="section-5.6-4.2.2.4.2.1">Reference bottleneck capacity:</dt>
                  <dd style="margin-left: 1.5em" id="section-5.6-4.2.2.4.2.2">2 Mbps<a href="#section-5.6-4.2.2.4.2.2" class="pilcrow">¶</a>
</dd>
                  <dd class="break"></dd>
<dt id="section-5.6-4.2.2.4.2.3">Path capacity ratio:</dt>
                  <dd style="margin-left: 1.5em" id="section-5.6-4.2.2.4.2.4">1.0<a href="#section-5.6-4.2.2.4.2.4" class="pilcrow">¶</a>
</dd>
                  <dd class="break"></dd>
<dt id="section-5.6-4.2.2.4.2.5">Bottleneck queue size:</dt>
                  <dd style="margin-left: 1.5em" id="section-5.6-4.2.2.4.2.6">[300 ms, 1000 ms]<a href="#section-5.6-4.2.2.4.2.6" class="pilcrow">¶</a>
</dd>
                <dd class="break"></dd>
</dl>
</dd>
              <dd class="break"></dd>
<dt id="section-5.6-4.2.2.5">Application-related:</dt>
              <dd style="margin-left: 1.5em" id="section-5.6-4.2.2.6">
                <p id="section-5.6-4.2.2.6.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.6-4.2.2.6.2">
                  <dt id="section-5.6-4.2.2.6.2.1">Media source:</dt>
                  <dd style="margin-left: 1.5em" id="section-5.6-4.2.2.6.2.2">
                    <p id="section-5.6-4.2.2.6.2.2.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.6-4.2.2.6.2.2.2">
                      <dt id="section-5.6-4.2.2.6.2.2.2.1">Media type:</dt>
                      <dd style="margin-left: 1.5em" id="section-5.6-4.2.2.6.2.2.2.2">
                        <p id="section-5.6-4.2.2.6.2.2.2.2.1">Video<a href="#section-5.6-4.2.2.6.2.2.2.2.1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-5.6-4.2.2.6.2.2.2.2.2">
                          <dt id="section-5.6-4.2.2.6.2.2.2.2.2.1">Media direction:</dt>
                          <dd style="margin-left: 1.5em" id="section-5.6-4.2.2.6.2.2.2.2.2.2">forward<a href="#section-5.6-4.2.2.6.2.2.2.2.2.2" class="pilcrow">¶</a>
</dd>
                          <dd class="break"></dd>
<dt id="section-5.6-4.2.2.6.2.2.2.2.2.3">Number of media sources:</dt>
                          <dd style="margin-left: 1.5em" id="section-5.6-4.2.2.6.2.2.2.2.2.4">one (1)<a href="#section-5.6-4.2.2.6.2.2.2.2.2.4" class="pilcrow">¶</a>
</dd>
                          <dd class="break"></dd>
<dt id="section-5.6-4.2.2.6.2.2.2.2.2.5">Media timeline:</dt>
                          <dd style="margin-left: 1.5em" id="section-5.6-4.2.2.6.2.2.2.2.2.6">
                            <p id="section-5.6-4.2.2.6.2.2.2.2.2.6.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.6-4.2.2.6.2.2.2.2.2.6.2">
                              <dt id="section-5.6-4.2.2.6.2.2.2.2.2.6.2.1">Start time:</dt>
                              <dd style="margin-left: 1.5em" id="section-5.6-4.2.2.6.2.2.2.2.2.6.2.2">5 s<a href="#section-5.6-4.2.2.6.2.2.2.2.2.6.2.2" class="pilcrow">¶</a>
</dd>
                              <dd class="break"></dd>
<dt id="section-5.6-4.2.2.6.2.2.2.2.2.6.2.3">End time:</dt>
                              <dd style="margin-left: 1.5em" id="section-5.6-4.2.2.6.2.2.2.2.2.6.2.4">119 s<a href="#section-5.6-4.2.2.6.2.2.2.2.2.6.2.4" class="pilcrow">¶</a>
</dd>
                            <dd class="break"></dd>
</dl>
</dd>
                        <dd class="break"></dd>
</dl>
</dd>
                      <dd class="break"></dd>
<dt id="section-5.6-4.2.2.6.2.2.2.3">Media type:</dt>
                      <dd style="margin-left: 1.5em" id="section-5.6-4.2.2.6.2.2.2.4">
                        <p id="section-5.6-4.2.2.6.2.2.2.4.1">Audio<a href="#section-5.6-4.2.2.6.2.2.2.4.1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-5.6-4.2.2.6.2.2.2.4.2">
                          <dt id="section-5.6-4.2.2.6.2.2.2.4.2.1">Media direction:</dt>
                          <dd style="margin-left: 1.5em" id="section-5.6-4.2.2.6.2.2.2.4.2.2">forward<a href="#section-5.6-4.2.2.6.2.2.2.4.2.2" class="pilcrow">¶</a>
</dd>
                          <dd class="break"></dd>
<dt id="section-5.6-4.2.2.6.2.2.2.4.2.3">Number of media sources:</dt>
                          <dd style="margin-left: 1.5em" id="section-5.6-4.2.2.6.2.2.2.4.2.4">one (1)<a href="#section-5.6-4.2.2.6.2.2.2.4.2.4" class="pilcrow">¶</a>
</dd>
                          <dd class="break"></dd>
<dt id="section-5.6-4.2.2.6.2.2.2.4.2.5">Media timeline:</dt>
                          <dd style="margin-left: 1.5em" id="section-5.6-4.2.2.6.2.2.2.4.2.6">
                            <p id="section-5.6-4.2.2.6.2.2.2.4.2.6.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.6-4.2.2.6.2.2.2.4.2.6.2">
                              <dt id="section-5.6-4.2.2.6.2.2.2.4.2.6.2.1">Start time:</dt>
                              <dd style="margin-left: 1.5em" id="section-5.6-4.2.2.6.2.2.2.4.2.6.2.2">5 s<a href="#section-5.6-4.2.2.6.2.2.2.4.2.6.2.2" class="pilcrow">¶</a>
</dd>
                              <dd class="break"></dd>
<dt id="section-5.6-4.2.2.6.2.2.2.4.2.6.2.3">End time:</dt>
                              <dd style="margin-left: 1.5em" id="section-5.6-4.2.2.6.2.2.2.4.2.6.2.4">119 s<a href="#section-5.6-4.2.2.6.2.2.2.4.2.6.2.4" class="pilcrow">¶</a>
</dd>
                            <dd class="break"></dd>
</dl>
</dd>
                        <dd class="break"></dd>
</dl>
</dd>
                    <dd class="break"></dd>
</dl>
<p id="section-5.6-4.2.2.6.2.2.3">Additionally, implementers are encouraged to run the
                experiment with multiple media sources.<a href="#section-5.6-4.2.2.6.2.2.3" class="pilcrow">¶</a></p>
</dd>
                  <dd class="break"></dd>
<dt id="section-5.6-4.2.2.6.2.3">Competing traffic:</dt>
                  <dd style="margin-left: 1.5em" id="section-5.6-4.2.2.6.2.4">
                    <p id="section-5.6-4.2.2.6.2.4.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.6-4.2.2.6.2.4.2">
                      <dt id="section-5.6-4.2.2.6.2.4.2.1">Number and types of sources:</dt>
                      <dd style="margin-left: 1.5em" id="section-5.6-4.2.2.6.2.4.2.2">one (1) and long-lived TCP<a href="#section-5.6-4.2.2.6.2.4.2.2" class="pilcrow">¶</a>
</dd>
                      <dd class="break"></dd>
<dt id="section-5.6-4.2.2.6.2.4.2.3">Traffic direction:</dt>
                      <dd style="margin-left: 1.5em" id="section-5.6-4.2.2.6.2.4.2.4">forward<a href="#section-5.6-4.2.2.6.2.4.2.4" class="pilcrow">¶</a>
</dd>
                      <dd class="break"></dd>
<dt id="section-5.6-4.2.2.6.2.4.2.5">Congestion control:</dt>
                      <dd style="margin-left: 1.5em" id="section-5.6-4.2.2.6.2.4.2.6">default TCP congestion control 
                       <span>[<a href="#RFC5681" class="xref">RFC5681</a>]</span>. Implementers are also encouraged to
                       run the experiment with alternative TCP congestion control algorithms.<a href="#section-5.6-4.2.2.6.2.4.2.6" class="pilcrow">¶</a>
</dd>
                      <dd class="break"></dd>
<dt id="section-5.6-4.2.2.6.2.4.2.7">Traffic timeline: </dt>
                      <dd style="margin-left: 1.5em" id="section-5.6-4.2.2.6.2.4.2.8">
                        <p id="section-5.6-4.2.2.6.2.4.2.8.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.6-4.2.2.6.2.4.2.8.2">
                          <dt id="section-5.6-4.2.2.6.2.4.2.8.2.1">Start time:</dt>
                          <dd style="margin-left: 1.5em" id="section-5.6-4.2.2.6.2.4.2.8.2.2">0 s<a href="#section-5.6-4.2.2.6.2.4.2.8.2.2" class="pilcrow">¶</a>
</dd>
                          <dd class="break"></dd>
<dt id="section-5.6-4.2.2.6.2.4.2.8.2.3">End time:</dt>
                          <dd style="margin-left: 1.5em" id="section-5.6-4.2.2.6.2.4.2.8.2.4">119 s<a href="#section-5.6-4.2.2.6.2.4.2.8.2.4" class="pilcrow">¶</a>
</dd>
                        <dd class="break"></dd>
</dl>
</dd>
                    <dd class="break"></dd>
</dl>
</dd>
                <dd class="break"></dd>
</dl>
</dd>
            <dd class="break"></dd>
</dl>
</dd>
          <dd class="break"></dd>
<dt id="section-5.6-4.3">Test-specific information:</dt>
          <dd style="margin-left: 1.5em" id="section-5.6-4.4">none<a href="#section-5.6-4.4" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
</dl>
</section>
<section id="section-5.7">
        <h3 id="name-media-flow-competing-with-s">
<a href="#section-5.7" class="section-number selfRef">5.7. </a><a href="#name-media-flow-competing-with-s" class="section-name selfRef">Media Flow Competing with Short TCP Flows</a>
        </h3>
<p id="section-5.7-1">In this test case, one or more congestion-controlled media flows
        share the bottleneck link with multiple short-lived TCP flows.
        Short-lived TCP flows resemble the on/off pattern observed in web
        traffic, wherein clients (for example, browsers) connect to a server
        and download a resource (typically a web page, few images, text files,
        etc.) using several TCP connections. This scenario shows the
        performance of a multimedia application when several browser windows
        are active. The test case measures the adaptivity of the candidate
        algorithm to competing web traffic, and it addresses requirement 1.E
        in <span><a href="https://www.rfc-editor.org/rfc/rfc8836#section-2" class="relref">Section 2</a> of [<a href="#RFC8836" class="xref">RFC8836</a>]</span>.<a href="#section-5.7-1" class="pilcrow">¶</a></p>
<p id="section-5.7-2">Depending on the number of short TCP flows, the cross traffic
        either appears as a short burst flow or resembles a long-lived TCP flow. The
        intention of this test is to observe the impact of a short-term burst on
        the behavior of the candidate algorithm.<a href="#section-5.7-2" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-5.7-3">
          <dt id="section-5.7-3.1">Expected behavior:</dt>
          <dd style="margin-left: 1.5em" id="section-5.7-3.2"> The candidate algorithm is expected to avoid
        flow starvation during the presence of short and bursty competing TCP
        flows, streaming at least at the minimum media bit rate. After
        competing TCP flows terminate, the media streams are expected to be
        robust enough to eventually recover to previous steady state behavior,
        and at the very least, avoid persistent starvation.<a href="#section-5.7-3.2" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-5.7-3.3">Evaluation metrics:</dt>
          <dd style="margin-left: 1.5em" id="section-5.7-3.4">
            <p id="section-5.7-3.4.1">Includes the following metrics in addition to those described
        in <a href="#EM" class="xref">Section 4.1</a>:<a href="#section-5.7-3.4.1" class="pilcrow">¶</a></p>
<ol start="1" type="1" class="normal type-1" id="section-5.7-3.4.2">
        <li id="section-5.7-3.4.2.1">
                <p id="section-5.7-3.4.2.1.1">Flow level:<a href="#section-5.7-3.4.2.1.1" class="pilcrow">¶</a></p>
<ol start="1" type="A" class="normal type-A" id="section-5.7-3.4.2.1.2">
             <li id="section-5.7-3.4.2.1.2.1">Variation in the sending rate of the TCP flow<a href="#section-5.7-3.4.2.1.2.1" class="pilcrow">¶</a>
</li>
                  <li id="section-5.7-3.4.2.1.2.2">TCP throughput<a href="#section-5.7-3.4.2.1.2.2" class="pilcrow">¶</a>
</li>
                </ol>
</li>
            </ol>
</dd>
          <dd class="break"></dd>
<dt id="section-5.7-3.5">Testbed topology:</dt>
          <dd style="margin-left: 1.5em" id="section-5.7-3.6">The topology described here is the same as the one
        described in <a href="#fig-eval-topo-4-4" class="xref">Figure 6</a>.<a href="#section-5.7-3.6" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-5.7-3.7">Testbed attributes:</dt>
          <dd style="margin-left: 1.5em" id="section-5.7-3.8">
            <p id="section-5.7-3.8.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.7-3.8.2">
              <dt id="section-5.7-3.8.2.1">Test duration:</dt>
              <dd style="margin-left: 1.5em" id="section-5.7-3.8.2.2">300 s<a href="#section-5.7-3.8.2.2" class="pilcrow">¶</a>
</dd>
              <dd class="break"></dd>
<dt id="section-5.7-3.8.2.3">Path characteristics:</dt>
              <dd style="margin-left: 1.5em" id="section-5.7-3.8.2.4">
                <p id="section-5.7-3.8.2.4.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.7-3.8.2.4.2">
                  <dt id="section-5.7-3.8.2.4.2.1">Reference bottleneck capacity:</dt>
                  <dd style="margin-left: 1.5em" id="section-5.7-3.8.2.4.2.2">2.0 Mbps<a href="#section-5.7-3.8.2.4.2.2" class="pilcrow">¶</a>
</dd>
                  <dd class="break"></dd>
<dt id="section-5.7-3.8.2.4.2.3">Path capacity ratio:</dt>
                  <dd style="margin-left: 1.5em" id="section-5.7-3.8.2.4.2.4">1.0<a href="#section-5.7-3.8.2.4.2.4" class="pilcrow">¶</a>
</dd>
                <dd class="break"></dd>
</dl>
</dd>
              <dd class="break"></dd>
<dt id="section-5.7-3.8.2.5">Application-related: </dt>
              <dd style="margin-left: 1.5em" id="section-5.7-3.8.2.6">
                <p id="section-5.7-3.8.2.6.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.7-3.8.2.6.2">
                  <dt id="section-5.7-3.8.2.6.2.1">Media source: </dt>
                  <dd style="margin-left: 1.5em" id="section-5.7-3.8.2.6.2.2">
                    <p id="section-5.7-3.8.2.6.2.2.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.7-3.8.2.6.2.2.2">
                      <dt id="section-5.7-3.8.2.6.2.2.2.1">Media type:</dt>
                      <dd style="margin-left: 1.5em" id="section-5.7-3.8.2.6.2.2.2.2">
                        <p id="section-5.7-3.8.2.6.2.2.2.2.1">Video<a href="#section-5.7-3.8.2.6.2.2.2.2.1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-5.7-3.8.2.6.2.2.2.2.2">
                          <dt id="section-5.7-3.8.2.6.2.2.2.2.2.1">Media direction:</dt>
                          <dd style="margin-left: 1.5em" id="section-5.7-3.8.2.6.2.2.2.2.2.2">forward<a href="#section-5.7-3.8.2.6.2.2.2.2.2.2" class="pilcrow">¶</a>
</dd>
                          <dd class="break"></dd>
<dt id="section-5.7-3.8.2.6.2.2.2.2.2.3">Number of media sources:</dt>
                          <dd style="margin-left: 1.5em" id="section-5.7-3.8.2.6.2.2.2.2.2.4">two (2)<a href="#section-5.7-3.8.2.6.2.2.2.2.2.4" class="pilcrow">¶</a>
</dd>
                          <dd class="break"></dd>
<dt id="section-5.7-3.8.2.6.2.2.2.2.2.5">Media timeline: </dt>
                          <dd style="margin-left: 1.5em" id="section-5.7-3.8.2.6.2.2.2.2.2.6">
                            <p id="section-5.7-3.8.2.6.2.2.2.2.2.6.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.7-3.8.2.6.2.2.2.2.2.6.2">
                              <dt id="section-5.7-3.8.2.6.2.2.2.2.2.6.2.1">Start time:</dt>
                              <dd style="margin-left: 1.5em" id="section-5.7-3.8.2.6.2.2.2.2.2.6.2.2">5 s<a href="#section-5.7-3.8.2.6.2.2.2.2.2.6.2.2" class="pilcrow">¶</a>
</dd>
                              <dd class="break"></dd>
<dt id="section-5.7-3.8.2.6.2.2.2.2.2.6.2.3">End time:</dt>
                              <dd style="margin-left: 1.5em" id="section-5.7-3.8.2.6.2.2.2.2.2.6.2.4">299 s<a href="#section-5.7-3.8.2.6.2.2.2.2.2.6.2.4" class="pilcrow">¶</a>
</dd>
                            <dd class="break"></dd>
</dl>
</dd>
                        <dd class="break"></dd>
</dl>
</dd>
                      <dd class="break"></dd>
<dt id="section-5.7-3.8.2.6.2.2.2.3">Media type:</dt>
                      <dd style="margin-left: 1.5em" id="section-5.7-3.8.2.6.2.2.2.4">
                        <p id="section-5.7-3.8.2.6.2.2.2.4.1">Audio<a href="#section-5.7-3.8.2.6.2.2.2.4.1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-5.7-3.8.2.6.2.2.2.4.2">
                          <dt id="section-5.7-3.8.2.6.2.2.2.4.2.1">Media direction:</dt>
                          <dd style="margin-left: 1.5em" id="section-5.7-3.8.2.6.2.2.2.4.2.2">forward<a href="#section-5.7-3.8.2.6.2.2.2.4.2.2" class="pilcrow">¶</a>
</dd>
                          <dd class="break"></dd>
<dt id="section-5.7-3.8.2.6.2.2.2.4.2.3">Number of media sources:</dt>
                          <dd style="margin-left: 1.5em" id="section-5.7-3.8.2.6.2.2.2.4.2.4"> two (2)<a href="#section-5.7-3.8.2.6.2.2.2.4.2.4" class="pilcrow">¶</a>
</dd>
                          <dd class="break"></dd>
<dt id="section-5.7-3.8.2.6.2.2.2.4.2.5">Media timeline: </dt>
                          <dd style="margin-left: 1.5em" id="section-5.7-3.8.2.6.2.2.2.4.2.6">
                            <p id="section-5.7-3.8.2.6.2.2.2.4.2.6.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.7-3.8.2.6.2.2.2.4.2.6.2">
                              <dt id="section-5.7-3.8.2.6.2.2.2.4.2.6.2.1">Start time:</dt>
                              <dd style="margin-left: 1.5em" id="section-5.7-3.8.2.6.2.2.2.4.2.6.2.2"> 5 s<a href="#section-5.7-3.8.2.6.2.2.2.4.2.6.2.2" class="pilcrow">¶</a>
</dd>
                              <dd class="break"></dd>
<dt id="section-5.7-3.8.2.6.2.2.2.4.2.6.2.3">End time: </dt>
                              <dd style="margin-left: 1.5em" id="section-5.7-3.8.2.6.2.2.2.4.2.6.2.4">299 s<a href="#section-5.7-3.8.2.6.2.2.2.4.2.6.2.4" class="pilcrow">¶</a>
</dd>
                            <dd class="break"></dd>
</dl>
</dd>
                        <dd class="break"></dd>
</dl>
</dd>
                    <dd class="break"></dd>
</dl>
</dd>
                  <dd class="break"></dd>
<dt id="section-5.7-3.8.2.6.2.3">Competing traffic: </dt>
                  <dd style="margin-left: 1.5em" id="section-5.7-3.8.2.6.2.4">
                    <p id="section-5.7-3.8.2.6.2.4.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.7-3.8.2.6.2.4.2">
                      <dt id="section-5.7-3.8.2.6.2.4.2.1">Number and types of sources:</dt>
                      <dd style="margin-left: 1.5em" id="section-5.7-3.8.2.6.2.4.2.2"> ten (10), short-lived TCP flows.<a href="#section-5.7-3.8.2.6.2.4.2.2" class="pilcrow">¶</a>
</dd>
                      <dd class="break"></dd>
<dt id="section-5.7-3.8.2.6.2.4.2.3">Traffic direction: </dt>
                      <dd style="margin-left: 1.5em" id="section-5.7-3.8.2.6.2.4.2.4">forward<a href="#section-5.7-3.8.2.6.2.4.2.4" class="pilcrow">¶</a>
</dd>
                      <dd class="break"></dd>
<dt id="section-5.7-3.8.2.6.2.4.2.5">Congestion algorithm:</dt>
                      <dd style="margin-left: 1.5em" id="section-5.7-3.8.2.6.2.4.2.6"> default TCP congestion control
                    <span>[<a href="#RFC5681" class="xref">RFC5681</a>]</span>. Implementers are also encouraged
                    to run the experiment with an alternative TCP congestion
                    control algorithm.<a href="#section-5.7-3.8.2.6.2.4.2.6" class="pilcrow">¶</a>
</dd>
                      <dd class="break"></dd>
<dt id="section-5.7-3.8.2.6.2.4.2.7">Traffic timeline: </dt>
                      <dd style="margin-left: 1.5em" id="section-5.7-3.8.2.6.2.4.2.8">Each short TCP flow is modeled as a
                    sequence of file downloads interleaved with idle periods.
                    Not all short TCP flows start at the same time, two of them
                    start in the ON state, while rest of the eight flows start in
                    an OFF state. For a description of the short TCP flow model, see
                    test-specific information below.<a href="#section-5.7-3.8.2.6.2.4.2.8" class="pilcrow">¶</a>
</dd>
                    <dd class="break"></dd>
</dl>
</dd>
                <dd class="break"></dd>
</dl>
</dd>
            <dd class="break"></dd>
</dl>
</dd>
          <dd class="break"></dd>
<dt id="section-5.7-3.9">Test-specific information: </dt>
          <dd style="margin-left: 1.5em" id="section-5.7-3.10">
            <p id="section-5.7-3.10.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.7-3.10.2">
              <dt id="section-5.7-3.10.2.1">Short TCP traffic model:</dt>
              <dd style="margin-left: 1.5em" id="section-5.7-3.10.2.2">The short TCP model to be used in
            this test is described in <span>[<a href="#RFC8868" class="xref">RFC8868</a>]</span>.<a href="#section-5.7-3.10.2.2" class="pilcrow">¶</a>
</dd>
            <dd class="break"></dd>
</dl>
</dd>
        <dd class="break"></dd>
</dl>
</section>
<section id="section-5.8">
        <h3 id="name-media-pause-and-resume">
<a href="#section-5.8" class="section-number selfRef">5.8. </a><a href="#name-media-pause-and-resume" class="section-name selfRef">Media Pause and Resume</a>
        </h3>
<p id="section-5.8-1">In this test case, more than one real-time interactive media flow
        share the link bandwidth, and all flows reach to a steady state by
        utilizing the link capacity in an optimum way. At this stage, one of
        the media flows is paused for a moment. This event will result in more
        available bandwidth for the rest of the flows as they are on a shared
        link. When the paused media flow resumes, it no longer has the
        same bandwidth share on the link. It has to make its way through the
        other existing flows in the link to achieve a fair share of the link
        capacity. This test case is important specially for real-time
        interactive media, which consists of more than one media flows and can
        pause/resume media flows at any point of time during the session. This
        test case directly addresses requirement 5 in 
        <span><a href="https://www.rfc-editor.org/rfc/rfc8836#section-2" class="relref">Section 2</a> of [<a href="#RFC8836" class="xref">RFC8836</a>]</span>. One can think of it as a
        variation of the test case defined in 
        <a href="#competing-rmcat-flow" class="xref">Section 5.4</a>. 
        However, it is different as the
        candidate algorithms can use different strategies to increase 
        efficiency, for example, in terms of fairness, convergence time,
        oscillation reduction, etc., by capitalizing on the fact that they have previous
        information of the link.<a href="#section-5.8-1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-5.8-2">
          <dt id="section-5.8-2.1">Expected behavior:</dt>
          <dd style="margin-left: 1.5em" id="section-5.8-2.2">During the period where the third stream is
        paused, the two remaining flows are expected to increase their rates
        and reach the maximum media bit rate. When the third stream resumes,
        all three flows are expected to converge to the same original fair
        share of rates prior to the media pause/resume event.<a href="#section-5.8-2.2" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-5.8-2.3">Evaluation metrics:</dt>
          <dd style="margin-left: 1.5em" id="section-5.8-2.4">
            <p id="section-5.8-2.4.1">Includes the following metrics in addition to those described
        in <a href="#EM" class="xref">Section 4.1</a>:<a href="#section-5.8-2.4.1" class="pilcrow">¶</a></p>
<ol start="1" type="1" class="normal type-1" id="section-5.8-2.4.2">
          <li id="section-5.8-2.4.2.1">
                <p id="section-5.8-2.4.2.1.1">Flow level:<a href="#section-5.8-2.4.2.1.1" class="pilcrow">¶</a></p>
<ol start="1" type="A" class="normal type-A" id="section-5.8-2.4.2.1.2">
              <li id="section-5.8-2.4.2.1.2.1">Variation in sending bit rate and throughput. Mainly
                observing the frequency and magnitude of oscillations.<a href="#section-5.8-2.4.2.1.2.1" class="pilcrow">¶</a>
</li>
                </ol>
</li>
            </ol>
</dd>
          <dd class="break"></dd>
<dt id="section-5.8-2.5">Testbed topology:</dt>
          <dd style="margin-left: 1.5em" id="section-5.8-2.6">Same as the test case defined in <a href="#competing-rmcat-flow" class="xref">Section 5.4</a>.<a href="#section-5.8-2.6" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-5.8-2.7">Testbed attributes:</dt>
          <dd style="margin-left: 1.5em" id="section-5.8-2.8">
            <p id="section-5.8-2.8.1">The general description of the testbed parameters are 
        the same as <a href="#competing-rmcat-flow" class="xref">Section 5.4</a> 
        with changes in the test-specific setup as below:<a href="#section-5.8-2.8.1" class="pilcrow">¶</a></p>
<p id="section-5.8-2.8.2">Other test-specific setup:<a href="#section-5.8-2.8.2" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-5.8-2.8.3">
              <dt id="section-5.8-2.8.3.1">Media flow timeline: </dt>
              <dd style="margin-left: 1.5em" id="section-5.8-2.8.3.2">
                <p id="section-5.8-2.8.3.2.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.8-2.8.3.2.2">
                  <dt id="section-5.8-2.8.3.2.2.1">Flow ID: </dt>
                  <dd style="margin-left: 1.5em" id="section-5.8-2.8.3.2.2.2">one (1)<a href="#section-5.8-2.8.3.2.2.2" class="pilcrow">¶</a>
</dd>
                  <dd class="break"></dd>
<dt id="section-5.8-2.8.3.2.2.3">Start time: </dt>
                  <dd style="margin-left: 1.5em" id="section-5.8-2.8.3.2.2.4">0 s<a href="#section-5.8-2.8.3.2.2.4" class="pilcrow">¶</a>
</dd>
                  <dd class="break"></dd>
<dt id="section-5.8-2.8.3.2.2.5">Flow duration: </dt>
                  <dd style="margin-left: 1.5em" id="section-5.8-2.8.3.2.2.6">119 s<a href="#section-5.8-2.8.3.2.2.6" class="pilcrow">¶</a>
</dd>
                  <dd class="break"></dd>
<dt id="section-5.8-2.8.3.2.2.7">Pause time: </dt>
                  <dd style="margin-left: 1.5em" id="section-5.8-2.8.3.2.2.8">not required<a href="#section-5.8-2.8.3.2.2.8" class="pilcrow">¶</a>
</dd>
                  <dd class="break"></dd>
<dt id="section-5.8-2.8.3.2.2.9">Resume time: </dt>
                  <dd style="margin-left: 1.5em" id="section-5.8-2.8.3.2.2.10">not required<a href="#section-5.8-2.8.3.2.2.10" class="pilcrow">¶</a>
</dd>
                <dd class="break"></dd>
</dl>
</dd>
              <dd class="break"></dd>
<dt id="section-5.8-2.8.3.3">Media flow timeline: </dt>
              <dd style="margin-left: 1.5em" id="section-5.8-2.8.3.4">
                <p id="section-5.8-2.8.3.4.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.8-2.8.3.4.2">
                  <dt id="section-5.8-2.8.3.4.2.1">Flow ID: </dt>
                  <dd style="margin-left: 1.5em" id="section-5.8-2.8.3.4.2.2">two (2)<a href="#section-5.8-2.8.3.4.2.2" class="pilcrow">¶</a>
</dd>
                  <dd class="break"></dd>
<dt id="section-5.8-2.8.3.4.2.3">Start time: </dt>
                  <dd style="margin-left: 1.5em" id="section-5.8-2.8.3.4.2.4">0 s<a href="#section-5.8-2.8.3.4.2.4" class="pilcrow">¶</a>
</dd>
                  <dd class="break"></dd>
<dt id="section-5.8-2.8.3.4.2.5">Flow duration: </dt>
                  <dd style="margin-left: 1.5em" id="section-5.8-2.8.3.4.2.6">119 s<a href="#section-5.8-2.8.3.4.2.6" class="pilcrow">¶</a>
</dd>
                  <dd class="break"></dd>
<dt id="section-5.8-2.8.3.4.2.7">Pause time: </dt>
                  <dd style="margin-left: 1.5em" id="section-5.8-2.8.3.4.2.8">at 40 s<a href="#section-5.8-2.8.3.4.2.8" class="pilcrow">¶</a>
</dd>
                  <dd class="break"></dd>
<dt id="section-5.8-2.8.3.4.2.9">Resume time: </dt>
                  <dd style="margin-left: 1.5em" id="section-5.8-2.8.3.4.2.10">at 60 s<a href="#section-5.8-2.8.3.4.2.10" class="pilcrow">¶</a>
</dd>
                <dd class="break"></dd>
</dl>
</dd>
              <dd class="break"></dd>
<dt id="section-5.8-2.8.3.5">Media flow timeline: </dt>
              <dd style="margin-left: 1.5em" id="section-5.8-2.8.3.6">
                <p id="section-5.8-2.8.3.6.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-5.8-2.8.3.6.2">
                  <dt id="section-5.8-2.8.3.6.2.1">Flow ID:</dt>
                  <dd style="margin-left: 1.5em" id="section-5.8-2.8.3.6.2.2">three (3)<a href="#section-5.8-2.8.3.6.2.2" class="pilcrow">¶</a>
</dd>
                  <dd class="break"></dd>
<dt id="section-5.8-2.8.3.6.2.3">Start time:</dt>
                  <dd style="margin-left: 1.5em" id="section-5.8-2.8.3.6.2.4">0 s<a href="#section-5.8-2.8.3.6.2.4" class="pilcrow">¶</a>
</dd>
                  <dd class="break"></dd>
<dt id="section-5.8-2.8.3.6.2.5">Flow duration:</dt>
                  <dd style="margin-left: 1.5em" id="section-5.8-2.8.3.6.2.6">119 s<a href="#section-5.8-2.8.3.6.2.6" class="pilcrow">¶</a>
</dd>
                  <dd class="break"></dd>
<dt id="section-5.8-2.8.3.6.2.7">Pause time:</dt>
                  <dd style="margin-left: 1.5em" id="section-5.8-2.8.3.6.2.8">not required<a href="#section-5.8-2.8.3.6.2.8" class="pilcrow">¶</a>
</dd>
                  <dd class="break"></dd>
<dt id="section-5.8-2.8.3.6.2.9">Resume time:</dt>
                  <dd style="margin-left: 1.5em" id="section-5.8-2.8.3.6.2.10">not required<a href="#section-5.8-2.8.3.6.2.10" class="pilcrow">¶</a>
</dd>
                <dd class="break"></dd>
</dl>
</dd>
            <dd class="break"></dd>
</dl>
</dd>
        <dd class="break"></dd>
</dl>
</section>
</section>
</div>
<section id="section-6">
      <h2 id="name-other-potential-test-cases">
<a href="#section-6" class="section-number selfRef">6. </a><a href="#name-other-potential-test-cases" class="section-name selfRef">Other Potential Test Cases</a>
      </h2>
<p id="section-6-1">It has been noticed that there are other interesting test cases
      besides the basic test cases listed above. In many aspects, these
      additional test cases can help further evaluation of the candidate
      algorithm. They are listed below.<a href="#section-6-1" class="pilcrow">¶</a></p>
<section id="section-6.1">
        <h3 id="name-media-flows-with-priority">
<a href="#section-6.1" class="section-number selfRef">6.1. </a><a href="#name-media-flows-with-priority" class="section-name selfRef">Media Flows with Priority</a>
        </h3>
<p id="section-6.1-1">In this test case, media flows will have different priority levels.
        This is an extension of <a href="#competing-rmcat-flow" class="xref">Section 5.4</a>
        where the same test is run with different priority levels imposed
        on each of the media flows. For example, the first flow (S1) is
        assigned a priority of 2, whereas the remaining two flows (S2 and S3)
        are assigned a priority of 1. The candidate algorithm must reflect the
        relative priorities assigned to each media flow. In this case, the
        first flow (S1) must arrive at a steady-state rate approximately twice
        that of the other two flows (S2 and S3).<a href="#section-6.1-1" class="pilcrow">¶</a></p>
<p id="section-6.1-2">The candidate algorithm can use a coupled congestion control
        mechanism <span>[<a href="#RFC8699" class="xref">RFC8699</a>]</span> or use a weighted
        priority scheduler for the bandwidth distribution according to the
        respective media flow priority or use.<a href="#section-6.1-2" class="pilcrow">¶</a></p>
</section>
<section id="section-6.2">
        <h3 id="name-explicit-congestion-notific">
<a href="#section-6.2" class="section-number selfRef">6.2. </a><a href="#name-explicit-congestion-notific" class="section-name selfRef">Explicit Congestion Notification Usage</a>
        </h3>
<p id="section-6.2-1">This test case requires running all the basic test cases with the
        availability of Explicit Congestion Notification (ECN) 
        <span>[<a href="#RFC6679" class="xref">RFC6679</a>]</span> feature enabled. The goal of this test is to
        exhibit that the candidate algorithms do not fail when ECN signals are
        available. With ECN signals enabled, the algorithms are expected to
        perform better than their delay-based variants.<a href="#section-6.2-1" class="pilcrow">¶</a></p>
</section>
<section id="section-6.3">
        <h3 id="name-multiple-bottlenecks">
<a href="#section-6.3" class="section-number selfRef">6.3. </a><a href="#name-multiple-bottlenecks" class="section-name selfRef">Multiple Bottlenecks</a>
        </h3>
<p id="section-6.3-1">In this test case, one congestion-controlled media flow, S1-&gt;R1,
        traverses a path with multiple bottlenecks. As illustrated in 
        <a href="#fig-eval-topo-6-2" class="xref">Figure 7</a>, the first flow (S1-&gt;R1) competes with
        the second congestion-controlled media flow (S2-&gt;R2) over the link
        between A and B, which is close to the sender side. Again, that flow
        (S1-&gt;R1) competes with the third congestion-controlled media flow
        (S3-&gt;R3) over the link between C and D, which is close to the
        receiver side. The goal of this test is to ensure that the candidate
        algorithms work properly in the presence of multiple bottleneck links
        on the end-to-end path.<a href="#section-6.3-1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-6.3-2">
          <dt id="section-6.3-2.1">Expected behavior:</dt>
          <dd style="margin-left: 1.5em" id="section-6.3-2.2"> The candidate algorithm is expected to achieve
        full utilization at both bottleneck links without starving any of the
        three congestion-controlled media flows and ensuring fair share of the
        available bandwidth at each bottleneck.<a href="#section-6.3-2.2" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
</dl>
<span id="name-testbed-topology-for-multipl"></span><div id="fig-eval-topo-6-2">
<figure id="figure-7">
          <div class="artwork art-text alignLeft" id="section-6.3-3.1">
<pre>
                             Forward ----&gt;

            +---+          +---+        +---+      +---+
            |S2 |          |R2 |        |S3 |      |R3 |
            +---+          +---+        +---+      +---+
              |              |            |          |
              |              |            |          |
+---+      +-----+       +-----+      +-----+     +-----+      +---+
|S1 |======|  A  |------&gt;|  B  |-----&gt;|  C  |----&gt;|  D  |======|R1 |
+---+      |     |&lt;------|     |&lt;-----|     |&lt;----|     |      +---+
           +-----+       +-----+      +-----+     +-----+

                    1st                       2nd
             Bottleneck (A-&gt;B)          Bottleneck (C-&gt;D)

                          &lt;------ Backward
</pre>
</div>
<figcaption><a href="#figure-7" class="selfRef">Figure 7</a>:
<a href="#name-testbed-topology-for-multipl" class="selfRef">Testbed Topology for Multiple Bottlenecks</a>
          </figcaption></figure>
</div>
<span class="break"></span><dl class="dlParallel" id="section-6.3-4">
          <dt id="section-6.3-4.1">Testbed topology:</dt>
          <dd style="margin-left: 1.5em" id="section-6.3-4.2">Three media sources S1, S2, and S3 are connected
      to respective destinations R1, R2, and R3. For all three flows, the
      media traffic is transported over the forward path, and the corresponding
      feedback/control traffic is transported over the backward path.<a href="#section-6.3-4.2" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt id="section-6.3-4.3">Testbed attributes:</dt>
          <dd style="margin-left: 1.5em" id="section-6.3-4.4">
            <p id="section-6.3-4.4.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-6.3-4.4.2">
              <dt id="section-6.3-4.4.2.1">Test duration:</dt>
              <dd style="margin-left: 1.5em" id="section-6.3-4.4.2.2"> 300 s<a href="#section-6.3-4.4.2.2" class="pilcrow">¶</a>
</dd>
              <dd class="break"></dd>
<dt id="section-6.3-4.4.2.3">Path characteristics: </dt>
              <dd style="margin-left: 1.5em" id="section-6.3-4.4.2.4">
                <p id="section-6.3-4.4.2.4.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-6.3-4.4.2.4.2">
                  <dt id="section-6.3-4.4.2.4.2.1">Reference bottleneck capacity:</dt>
                  <dd style="margin-left: 1.5em" id="section-6.3-4.4.2.4.2.2">2 Mbps<a href="#section-6.3-4.4.2.4.2.2" class="pilcrow">¶</a>
</dd>
                  <dd class="break"></dd>
<dt id="section-6.3-4.4.2.4.2.3">Path capacity ratio between A and B:</dt>
                  <dd style="margin-left: 1.5em" id="section-6.3-4.4.2.4.2.4">1.0<a href="#section-6.3-4.4.2.4.2.4" class="pilcrow">¶</a>
</dd>
                  <dd class="break"></dd>
<dt id="section-6.3-4.4.2.4.2.5">Path capacity ratio between B and C:</dt>
                  <dd style="margin-left: 1.5em" id="section-6.3-4.4.2.4.2.6">4.0<a href="#section-6.3-4.4.2.4.2.6" class="pilcrow">¶</a>
</dd>
                  <dd class="break"></dd>
<dt id="section-6.3-4.4.2.4.2.7">Path capacity ratio between C and D:</dt>
                  <dd style="margin-left: 1.5em" id="section-6.3-4.4.2.4.2.8">0.75<a href="#section-6.3-4.4.2.4.2.8" class="pilcrow">¶</a>
</dd>
                  <dd class="break"></dd>
<dt id="section-6.3-4.4.2.4.2.9">One-way propagation delay: </dt>
                  <dd style="margin-left: 1.5em" id="section-6.3-4.4.2.4.2.10">
                    <p id="section-6.3-4.4.2.4.2.10.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-6.3-4.4.2.4.2.10.2">
                      <dt id="section-6.3-4.4.2.4.2.10.2.1">Between S1 and R1:</dt>
                      <dd style="margin-left: 1.5em" id="section-6.3-4.4.2.4.2.10.2.2">100 ms<a href="#section-6.3-4.4.2.4.2.10.2.2" class="pilcrow">¶</a>
</dd>
                      <dd class="break"></dd>
<dt id="section-6.3-4.4.2.4.2.10.2.3">Between S2 and R2:</dt>
                      <dd style="margin-left: 1.5em" id="section-6.3-4.4.2.4.2.10.2.4">40 ms<a href="#section-6.3-4.4.2.4.2.10.2.4" class="pilcrow">¶</a>
</dd>
                      <dd class="break"></dd>
<dt id="section-6.3-4.4.2.4.2.10.2.5">Between S3 and R3:</dt>
                      <dd style="margin-left: 1.5em" id="section-6.3-4.4.2.4.2.10.2.6">40 ms<a href="#section-6.3-4.4.2.4.2.10.2.6" class="pilcrow">¶</a>
</dd>
                    <dd class="break"></dd>
</dl>
</dd>
                <dd class="break"></dd>
</dl>
</dd>
              <dd class="break"></dd>
<dt id="section-6.3-4.4.2.5">Application-related: </dt>
              <dd style="margin-left: 1.5em" id="section-6.3-4.4.2.6">
                <p id="section-6.3-4.4.2.6.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-6.3-4.4.2.6.2">
                  <dt id="section-6.3-4.4.2.6.2.1">Media source:</dt>
                  <dd style="margin-left: 1.5em" id="section-6.3-4.4.2.6.2.2">
                    <p id="section-6.3-4.4.2.6.2.2.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-6.3-4.4.2.6.2.2.2">
                      <dt id="section-6.3-4.4.2.6.2.2.2.1">Media type:</dt>
                      <dd style="margin-left: 1.5em" id="section-6.3-4.4.2.6.2.2.2.2">
                        <p id="section-6.3-4.4.2.6.2.2.2.2.1">Video<a href="#section-6.3-4.4.2.6.2.2.2.2.1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-6.3-4.4.2.6.2.2.2.2.2">
                          <dt id="section-6.3-4.4.2.6.2.2.2.2.2.1">Media direction:</dt>
                          <dd style="margin-left: 1.5em" id="section-6.3-4.4.2.6.2.2.2.2.2.2">Forward<a href="#section-6.3-4.4.2.6.2.2.2.2.2.2" class="pilcrow">¶</a>
</dd>
                          <dd class="break"></dd>
<dt id="section-6.3-4.4.2.6.2.2.2.2.2.3">Number of media sources:</dt>
                          <dd style="margin-left: 1.5em" id="section-6.3-4.4.2.6.2.2.2.2.2.4">Three (3)<a href="#section-6.3-4.4.2.6.2.2.2.2.2.4" class="pilcrow">¶</a>
</dd>
                          <dd class="break"></dd>
<dt id="section-6.3-4.4.2.6.2.2.2.2.2.5">Media timeline: </dt>
                          <dd style="margin-left: 1.5em" id="section-6.3-4.4.2.6.2.2.2.2.2.6">
                            <p id="section-6.3-4.4.2.6.2.2.2.2.2.6.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-6.3-4.4.2.6.2.2.2.2.2.6.2">
                              <dt id="section-6.3-4.4.2.6.2.2.2.2.2.6.2.1">Start time:</dt>
                              <dd style="margin-left: 1.5em" id="section-6.3-4.4.2.6.2.2.2.2.2.6.2.2"> 0 s<a href="#section-6.3-4.4.2.6.2.2.2.2.2.6.2.2" class="pilcrow">¶</a>
</dd>
                              <dd class="break"></dd>
<dt id="section-6.3-4.4.2.6.2.2.2.2.2.6.2.3">End time: </dt>
                              <dd style="margin-left: 1.5em" id="section-6.3-4.4.2.6.2.2.2.2.2.6.2.4">299 s<a href="#section-6.3-4.4.2.6.2.2.2.2.2.6.2.4" class="pilcrow">¶</a>
</dd>
                            <dd class="break"></dd>
</dl>
</dd>
                        <dd class="break"></dd>
</dl>
</dd>
                      <dd class="break"></dd>
<dt id="section-6.3-4.4.2.6.2.2.2.3">Media type:</dt>
                      <dd style="margin-left: 1.5em" id="section-6.3-4.4.2.6.2.2.2.4">
                        <p id="section-6.3-4.4.2.6.2.2.2.4.1">Audio<a href="#section-6.3-4.4.2.6.2.2.2.4.1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-6.3-4.4.2.6.2.2.2.4.2">
                          <dt id="section-6.3-4.4.2.6.2.2.2.4.2.1">Media direction:</dt>
                          <dd style="margin-left: 1.5em" id="section-6.3-4.4.2.6.2.2.2.4.2.2">Forward<a href="#section-6.3-4.4.2.6.2.2.2.4.2.2" class="pilcrow">¶</a>
</dd>
                          <dd class="break"></dd>
<dt id="section-6.3-4.4.2.6.2.2.2.4.2.3">Number of media sources:</dt>
                          <dd style="margin-left: 1.5em" id="section-6.3-4.4.2.6.2.2.2.4.2.4">Three (3)<a href="#section-6.3-4.4.2.6.2.2.2.4.2.4" class="pilcrow">¶</a>
</dd>
                          <dd class="break"></dd>
<dt id="section-6.3-4.4.2.6.2.2.2.4.2.5">Media timeline: </dt>
                          <dd style="margin-left: 1.5em" id="section-6.3-4.4.2.6.2.2.2.4.2.6">
                            <p id="section-6.3-4.4.2.6.2.2.2.4.2.6.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-6.3-4.4.2.6.2.2.2.4.2.6.2">
                              <dt id="section-6.3-4.4.2.6.2.2.2.4.2.6.2.1">Start time:</dt>
                              <dd style="margin-left: 1.5em" id="section-6.3-4.4.2.6.2.2.2.4.2.6.2.2">0 s<a href="#section-6.3-4.4.2.6.2.2.2.4.2.6.2.2" class="pilcrow">¶</a>
</dd>
                              <dd class="break"></dd>
<dt id="section-6.3-4.4.2.6.2.2.2.4.2.6.2.3">End time:</dt>
                              <dd style="margin-left: 1.5em" id="section-6.3-4.4.2.6.2.2.2.4.2.6.2.4">299 s<a href="#section-6.3-4.4.2.6.2.2.2.4.2.6.2.4" class="pilcrow">¶</a>
</dd>
                            <dd class="break"></dd>
</dl>
</dd>
                        <dd class="break"></dd>
</dl>
</dd>
                    <dd class="break"></dd>
</dl>
</dd>
                  <dd class="break"></dd>
<dt id="section-6.3-4.4.2.6.2.3">Competing traffic: </dt>
                  <dd style="margin-left: 1.5em" id="section-6.3-4.4.2.6.2.4">
                    <p id="section-6.3-4.4.2.6.2.4.1"><br></p>
<span class="break"></span><dl class="dlParallel" id="section-6.3-4.4.2.6.2.4.2">
                      <dt id="section-6.3-4.4.2.6.2.4.2.1">Number of sources:</dt>
                      <dd style="margin-left: 1.5em" id="section-6.3-4.4.2.6.2.4.2.2">Zero (0)<a href="#section-6.3-4.4.2.6.2.4.2.2" class="pilcrow">¶</a>
</dd>
                    <dd class="break"></dd>
</dl>
</dd>
                <dd class="break"></dd>
</dl>
</dd>
            <dd class="break"></dd>
</dl>
</dd>
        <dd class="break"></dd>
</dl>
</section>
</section>
<section id="section-7">
      <h2 id="name-wireless-access-links">
<a href="#section-7" class="section-number selfRef">7. </a><a href="#name-wireless-access-links" class="section-name selfRef">Wireless Access Links</a>
      </h2>
<p id="section-7-1">Additional wireless network (both cellular network and Wi-Fi network)
      specific test cases are defined in <span>[<a href="#RFC8869" class="xref">RFC8869</a>]</span>.<a href="#section-7-1" class="pilcrow">¶</a></p>
</section>
<section id="section-8">
      <h2 id="name-security-considerations">
<a href="#section-8" class="section-number selfRef">8. </a><a href="#name-security-considerations" class="section-name selfRef">Security Considerations</a>
      </h2>
<p id="section-8-1">The security considerations in <span><a href="https://www.rfc-editor.org/rfc/rfc8868#section-6" class="relref">Section 6</a> of [<a href="#RFC8868" class="xref">RFC8868</a>]</span> and the relevant congestion
      control algorithms apply. The principles for congestion control are
      described in <span>[<a href="#RFC2914" class="xref">RFC2914</a>]</span>, and in particular any new method
      must implement safeguards to avoid congestion collapse of the
      Internet.<a href="#section-8-1" class="pilcrow">¶</a></p>
<p id="section-8-2">The evaluation of the test cases are intended to be run in a
      controlled lab environment. Hence, the applications, simulators, and
      network nodes ought to be well-behaved and should not impact the desired
      results. Moreover, proper measures must be taken to avoid leaking
      nonresponsive traffic from unproven congestion avoidance techniques
      onto the open Internet.<a href="#section-8-2" class="pilcrow">¶</a></p>
</section>
<section id="section-9">
      <h2 id="name-iana-considerations">
<a href="#section-9" class="section-number selfRef">9. </a><a href="#name-iana-considerations" class="section-name selfRef">IANA Considerations</a>
      </h2>
<p id="section-9-1">This document has no IANA actions.<a href="#section-9-1" class="pilcrow">¶</a></p>
</section>
<section id="section-10">
      <h2 id="name-references">
<a href="#section-10" class="section-number selfRef">10. </a><a href="#name-references" class="section-name selfRef">References</a>
      </h2>
<section id="section-10.1">
        <h3 id="name-normative-references">
<a href="#section-10.1" class="section-number selfRef">10.1. </a><a href="#name-normative-references" class="section-name selfRef">Normative References</a>
        </h3>
<dl class="references">
<dt id="RFC3550">[RFC3550]</dt>
        <dd>
<span class="refAuthor">Schulzrinne, H.</span><span class="refAuthor">, Casner, S.</span><span class="refAuthor">, Frederick, R.</span><span class="refAuthor">, and V. Jacobson</span>, <span class="refTitle">"RTP: A Transport Protocol for Real-Time Applications"</span>, <span class="seriesInfo">STD 64</span>, <span class="seriesInfo">RFC 3550</span>, <span class="seriesInfo">DOI 10.17487/RFC3550</span>, <time datetime="2003-07" class="refDate">July 2003</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc3550">https://www.rfc-editor.org/info/rfc3550</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC3551">[RFC3551]</dt>
        <dd>
<span class="refAuthor">Schulzrinne, H.</span><span class="refAuthor"> and S. Casner</span>, <span class="refTitle">"RTP Profile for Audio and Video Conferences with Minimal Control"</span>, <span class="seriesInfo">STD 65</span>, <span class="seriesInfo">RFC 3551</span>, <span class="seriesInfo">DOI 10.17487/RFC3551</span>, <time datetime="2003-07" class="refDate">July 2003</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc3551">https://www.rfc-editor.org/info/rfc3551</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC3611">[RFC3611]</dt>
        <dd>
<span class="refAuthor">Friedman, T., Ed.</span><span class="refAuthor">, Caceres, R., Ed.</span><span class="refAuthor">, and A. Clark, Ed.</span>, <span class="refTitle">"RTP Control Protocol Extended Reports (RTCP XR)"</span>, <span class="seriesInfo">RFC 3611</span>, <span class="seriesInfo">DOI 10.17487/RFC3611</span>, <time datetime="2003-11" class="refDate">November 2003</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc3611">https://www.rfc-editor.org/info/rfc3611</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC4585">[RFC4585]</dt>
        <dd>
<span class="refAuthor">Ott, J.</span><span class="refAuthor">, Wenger, S.</span><span class="refAuthor">, Sato, N.</span><span class="refAuthor">, Burmeister, C.</span><span class="refAuthor">, and J. Rey</span>, <span class="refTitle">"Extended RTP Profile for Real-time Transport Control Protocol (RTCP)-Based Feedback (RTP/AVPF)"</span>, <span class="seriesInfo">RFC 4585</span>, <span class="seriesInfo">DOI 10.17487/RFC4585</span>, <time datetime="2006-07" class="refDate">July 2006</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc4585">https://www.rfc-editor.org/info/rfc4585</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC5506">[RFC5506]</dt>
        <dd>
<span class="refAuthor">Johansson, I.</span><span class="refAuthor"> and M. Westerlund</span>, <span class="refTitle">"Support for Reduced-Size Real-Time Transport Control Protocol (RTCP): Opportunities and Consequences"</span>, <span class="seriesInfo">RFC 5506</span>, <span class="seriesInfo">DOI 10.17487/RFC5506</span>, <time datetime="2009-04" class="refDate">April 2009</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc5506">https://www.rfc-editor.org/info/rfc5506</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC5681">[RFC5681]</dt>
        <dd>
<span class="refAuthor">Allman, M.</span><span class="refAuthor">, Paxson, V.</span><span class="refAuthor">, and E. Blanton</span>, <span class="refTitle">"TCP Congestion Control"</span>, <span class="seriesInfo">RFC 5681</span>, <span class="seriesInfo">DOI 10.17487/RFC5681</span>, <time datetime="2009-09" class="refDate">September 2009</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc5681">https://www.rfc-editor.org/info/rfc5681</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC6679">[RFC6679]</dt>
        <dd>
<span class="refAuthor">Westerlund, M.</span><span class="refAuthor">, Johansson, I.</span><span class="refAuthor">, Perkins, C.</span><span class="refAuthor">, O'Hanlon, P.</span><span class="refAuthor">, and K. Carlberg</span>, <span class="refTitle">"Explicit Congestion Notification (ECN) for RTP over UDP"</span>, <span class="seriesInfo">RFC 6679</span>, <span class="seriesInfo">DOI 10.17487/RFC6679</span>, <time datetime="2012-08" class="refDate">August 2012</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc6679">https://www.rfc-editor.org/info/rfc6679</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8593">[RFC8593]</dt>
        <dd>
<span class="refAuthor">Zhu, X.</span><span class="refAuthor">, Mena, S.</span><span class="refAuthor">, and Z. Sarker</span>, <span class="refTitle">"Video Traffic Models for RTP Congestion Control Evaluations"</span>, <span class="seriesInfo">RFC 8593</span>, <span class="seriesInfo">DOI 10.17487/RFC8593</span>, <time datetime="2019-05" class="refDate">May 2019</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8593">https://www.rfc-editor.org/info/rfc8593</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8836">[RFC8836]</dt>
        <dd>
<span class="refAuthor">Jesup, R.</span><span class="refAuthor"> and Z. Sarker, Ed.</span>, <span class="refTitle">"Congestion Control Requirements for Interactive Real-Time Media"</span>, <span class="seriesInfo">RFC 8836</span>, <span class="seriesInfo">DOI 10.17487/RFC8836</span>, <time datetime="2021-01" class="refDate">January 2021</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8836">https://www.rfc-editor.org/info/rfc8836</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8868">[RFC8868]</dt>
        <dd>
<span class="refAuthor">Singh, V.</span><span class="refAuthor">, Ott, J.</span><span class="refAuthor">, and S. Holmer</span>, <span class="refTitle">"Evaluating Congestion Control for Interactive Real-Time Media"</span>, <span class="seriesInfo">RFC 8868</span>, <span class="seriesInfo">DOI 10.17487/RFC8868</span>, <time datetime="2021-01" class="refDate">January 2021</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8868">https://www.rfc-editor.org/info/rfc8868</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8869">[RFC8869]</dt>
      <dd>
<span class="refAuthor">Sarker, Z.</span><span class="refAuthor">, Zhu, X.</span><span class="refAuthor">, and J. Fu</span>, <span class="refTitle">"Evaluation Test Cases for Interactive Real-Time Media over Wireless Networks"</span>, <span class="seriesInfo">RFC 8869</span>, <span class="seriesInfo">DOI 10.17487/RFC8869</span>, <time datetime="2021-01" class="refDate">January 2021</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8869">https://www.rfc-editor.org/info/rfc8869</a>&gt;</span>. </dd>
<dd class="break"></dd>
</dl>
</section>
<section id="section-10.2">
        <h3 id="name-informative-references">
<a href="#section-10.2" class="section-number selfRef">10.2. </a><a href="#name-informative-references" class="section-name selfRef">Informative References</a>
        </h3>
<dl class="references">
<dt id="HEVC-seq">[HEVC-seq]</dt>
        <dd>
<span class="refAuthor">HEVC</span>, <span class="refTitle">"Test Sequences"</span>, <span>&lt;<a href="http://www.netlab.tkk.fi/~varun/test_sequences/">http://www.netlab.tkk.fi/~varun/test_sequences/</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC2914">[RFC2914]</dt>
        <dd>
<span class="refAuthor">Floyd, S.</span>, <span class="refTitle">"Congestion Control Principles"</span>, <span class="seriesInfo">BCP 41</span>, <span class="seriesInfo">RFC 2914</span>, <span class="seriesInfo">DOI 10.17487/RFC2914</span>, <time datetime="2000-09" class="refDate">September 2000</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc2914">https://www.rfc-editor.org/info/rfc2914</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC7567">[RFC7567]</dt>
        <dd>
<span class="refAuthor">Baker, F., Ed.</span><span class="refAuthor"> and G. Fairhurst, Ed.</span>, <span class="refTitle">"IETF Recommendations Regarding Active Queue Management"</span>, <span class="seriesInfo">BCP 197</span>, <span class="seriesInfo">RFC 7567</span>, <span class="seriesInfo">DOI 10.17487/RFC7567</span>, <time datetime="2015-07" class="refDate">July 2015</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc7567">https://www.rfc-editor.org/info/rfc7567</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8033">[RFC8033]</dt>
        <dd>
<span class="refAuthor">Pan, R.</span><span class="refAuthor">, Natarajan, P.</span><span class="refAuthor">, Baker, F.</span><span class="refAuthor">, and G. White</span>, <span class="refTitle">"Proportional Integral Controller Enhanced (PIE): A Lightweight Control Scheme to Address the Bufferbloat Problem"</span>, <span class="seriesInfo">RFC 8033</span>, <span class="seriesInfo">DOI 10.17487/RFC8033</span>, <time datetime="2017-02" class="refDate">February 2017</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8033">https://www.rfc-editor.org/info/rfc8033</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8290">[RFC8290]</dt>
        <dd>
<span class="refAuthor">Hoeiland-Joergensen, T.</span><span class="refAuthor">, McKenney, P.</span><span class="refAuthor">, Taht, D.</span><span class="refAuthor">, Gettys, J.</span><span class="refAuthor">, and E. Dumazet</span>, <span class="refTitle">"The Flow Queue CoDel Packet Scheduler and Active Queue Management Algorithm"</span>, <span class="seriesInfo">RFC 8290</span>, <span class="seriesInfo">DOI 10.17487/RFC8290</span>, <time datetime="2018-01" class="refDate">January 2018</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8290">https://www.rfc-editor.org/info/rfc8290</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8699">[RFC8699]</dt>
        <dd>
<span class="refAuthor">Islam, S.</span><span class="refAuthor">, Welzl, M.</span><span class="refAuthor">, and S. Gjessing</span>, <span class="refTitle">"Coupled Congestion Control for RTP Media"</span>, <span class="seriesInfo">RFC 8699</span>, <span class="seriesInfo">DOI 10.17487/RFC8699</span>, <time datetime="2020-01" class="refDate">January 2020</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8699">https://www.rfc-editor.org/info/rfc8699</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="xiph-seq">[xiph-seq]</dt>
      <dd>
<span class="refAuthor">Xiph.org</span>, <span class="refTitle">"Video Test Media"</span>, <span>&lt;<a href="http://media.xiph.org/video/derf/">http://media.xiph.org/video/derf/</a>&gt;</span>. </dd>
<dd class="break"></dd>
</dl>
</section>
</section>
<section id="section-appendix.a">
      <h2 id="name-acknowledgments">
<a href="#name-acknowledgments" class="section-name selfRef">Acknowledgments</a>
      </h2>
<p id="section-appendix.a-1">Much of this document is derived from previous work on congestion
      control at the IETF.<a href="#section-appendix.a-1" class="pilcrow">¶</a></p>
<p id="section-appendix.a-2">The content and concepts within this document are a product of the
      discussion carried out within the Design Team.<a href="#section-appendix.a-2" class="pilcrow">¶</a></p>
</section>
<div id="authors-addresses">
<section id="section-appendix.b">
      <h2 id="name-authors-addresses">
<a href="#name-authors-addresses" class="section-name selfRef">Authors' Addresses</a>
      </h2>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">Zaheduzzaman Sarker</span></div>
<div dir="auto" class="left"><span class="org">Ericsson AB</span></div>
<div dir="auto" class="left"><span class="street-address">Torshamnsgatan 23</span></div>
<div dir="auto" class="left">SE-<span class="postal-code">164 83</span> <span class="locality">Stockholm</span>
</div>
<div dir="auto" class="left"><span class="country-name">Sweden</span></div>
<div class="tel">
<span>Phone:</span>
<a href="tel:+46%2010%20717%2037%2043" class="tel">+46 10 717 37 43</a>
</div>
<div class="email">
<span>Email:</span>
<a href="mailto:zaheduzzaman.sarker@ericsson.com" class="email">zaheduzzaman.sarker@ericsson.com</a>
</div>
</address>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">Varun Singh</span></div>
<div dir="auto" class="left"><span class="org">CALLSTATS I/O Oy</span></div>
<div dir="auto" class="left"><span class="street-address">Rauhankatu 11 C</span></div>
<div dir="auto" class="left">FI-<span class="postal-code">00100</span> <span class="locality">Helsinki</span>
</div>
<div dir="auto" class="left"><span class="country-name">Finland</span></div>
<div class="email">
<span>Email:</span>
<a href="mailto:varun.singh@iki.fi" class="email">varun.singh@iki.fi</a>
</div>
<div class="url">
<span>URI:</span>
<a href="http://www.callstats.io/" class="url">http://www.callstats.io/</a>
</div>
</address>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">Xiaoqing Zhu</span></div>
<div dir="auto" class="left"><span class="org">Cisco Systems</span></div>
<div dir="auto" class="left"><span class="street-address">12515 Research Blvd</span></div>
<div dir="auto" class="left">
<span class="locality">Austin</span>, <span class="region">TX</span> <span class="postal-code">78759</span>
</div>
<div dir="auto" class="left"><span class="country-name">United States of America</span></div>
<div class="email">
<span>Email:</span>
<a href="mailto:xiaoqzhu@cisco.com" class="email">xiaoqzhu@cisco.com</a>
</div>
</address>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">Michael A. Ramalho</span></div>
<div dir="auto" class="left"><span class="org">AcousticComms Consulting</span></div>
<div dir="auto" class="left"><span class="street-address">6310 Watercrest Way Unit 203</span></div>
<div dir="auto" class="left">
<span class="locality">Lakewood Ranch</span>, <span class="region">FL</span> <span class="postal-code">34202-5211</span>
</div>
<div dir="auto" class="left"><span class="country-name">United States of America</span></div>
<div class="tel">
<span>Phone:</span>
<a href="tel:+1%20732%20832%209723" class="tel">+1 732 832 9723</a>
</div>
<div class="email">
<span>Email:</span>
<a href="mailto:mar42@cornell.edu" class="email">mar42@cornell.edu</a>
</div>
<div class="url">
<span>URI:</span>
<a href="http://ramalho.webhop.info/" class="url">http://ramalho.webhop.info/</a>
</div>
</address>
</section>
</div>
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