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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 8892: Guidelines and Registration Procedures for Interface Types and Tunnel Types</title>
<meta content="Dave Thaler" name="author">
<meta content="Dan Romascanu" name="author">
<meta content='
       This document provides guidelines and procedures for those who are defining, registering, 
or evaluating definitions of new interface types ("ifType" values) and tunnel types.
The original definition of the IANA interface type registry predated
the use of IANA Considerations sections and YANG modules, so some confusion arose
over time. Tunnel types were added later, with the same requirements and allocation policy as
interface types. This document updates RFC 2863 and provides updated guidance for
these registries. 
    ' name="description">
<meta content="xml2rfc 2.47.0" name="generator">
<meta content="ifType" name="keyword">
<meta content="tunnelType" name="keyword">
<meta content="Transmission Number" name="keyword">
<meta content="8892" name="rfc.number">
<link href="rfc8892.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;
  font-family: 'Noto Sans', Arial, Helvetica, sans-serif;
  line-height: 1.6;
  scroll-behavior: smooth;
}
.ears {
  display: none;
}

/* headings */
#title, h1, h2, h3, h4, h5, h6 {
  margin: 1em 0 0.5em;
  font-weight: bold;
  line-height: 1.3;
}
#title {
  clear: both;
  border-bottom: 1px solid #ddd;
  margin: 0 0 0.5em 0;
  padding: 1em 0 0.5em;
}
.author {
  padding-bottom: 4px;
}
h1 {
  font-size: 26px;
  margin: 1em 0;
}
h2 {
  font-size: 22px;
  margin-top: -20px;  /* provide offset for in-page anchors */
  padding-top: 33px;
}
h3 {
  font-size: 18px;
  margin-top: -36px;  /* provide offset for in-page anchors */
  padding-top: 42px;
}
h4 {
  font-size: 16px;
  margin-top: -36px;  /* provide offset for in-page anchors */
  padding-top: 42px;
}
h5, h6 {
  font-size: 14px;
}
#n-copyright-notice {
  border-bottom: 1px solid #ddd;
  padding-bottom: 1em;
  margin-bottom: 1em;
}
/* general structure */
p {
  padding: 0;
  margin: 0 0 1em 0;
  text-align: left;
}
div, span {
  position: relative;
}
div {
  margin: 0;
}
.alignRight.art-text {
  background-color: #f9f9f9;
  border: 1px solid #eee;
  border-radius: 3px;
  padding: 1em 1em 0;
  margin-bottom: 1.5em;
}
.alignRight.art-text pre {
  padding: 0;
}
.alignRight {
  margin: 1em 0;
}
.alignRight > *:first-child {
  border: none;
  margin: 0;
  float: right;
  clear: both;
}
.alignRight > *:nth-child(2) {
  clear: both;
  display: block;
  border: none;
}
svg {
  display: block;
}
.alignCenter.art-text {
  background-color: #f9f9f9;
  border: 1px solid #eee;
  border-radius: 3px;
  padding: 1em 1em 0;
  margin-bottom: 1.5em;
}
.alignCenter.art-text pre {
  padding: 0;
}
.alignCenter {
  margin: 1em 0;
}
.alignCenter > *:first-child {
  border: none;
  /* this isn't optimal, but it's an existence proof.  PrinceXML doesn't
     support flexbox yet.
  */
  display: table;
  margin: 0 auto;
}

/* lists */
ol, ul {
  padding: 0;
  margin: 0 0 1em 2em;
}
ol ol, ul ul, ol ul, ul ol {
  margin-left: 1em;
}
li {
  margin: 0 0 0.25em 0;
}
.ulCompact li {
  margin: 0;
}
ul.empty, .ulEmpty {
  list-style-type: none;
}
ul.empty li, .ulEmpty li {
  margin-top: 0.5em;
}
ul.compact, .ulCompact,
ol.compact, .olCompact {
  line-height: 100%;
  margin: 0 0 0 2em;
}

/* definition lists */
dl {
}
dl > dt {
  float: left;
  margin-right: 1em;
}
/* 
dl.nohang > dt {
  float: none;
}
*/
dl > dd {
  margin-bottom: .8em;
  min-height: 1.3em;
}
dl.compact > dd, .dlCompact > dd {
  margin-bottom: 0em;
}
dl > dd > dl {
  margin-top: 0.5em;
  margin-bottom: 0em;
}

/* links */
a {
  text-decoration: none;
}
a[href] {
  color: #22e; /* Arlen: WCAG 2019 */
}
a[href]:hover {
  background-color: #f2f2f2;
}
figcaption a[href],
a[href].selfRef {
  color: #222;
}
/* XXX probably not this:
a.selfRef:hover {
  background-color: transparent;
  cursor: default;
} */

/* Figures */
tt, code, pre, code {
  background-color: #f9f9f9;
  font-family: 'Roboto Mono', monospace;
}
pre {
  border: 1px solid #eee;
  margin: 0;
  padding: 1em;
}
img {
  max-width: 100%;
}
figure {
  margin: 0;
}
figure blockquote {
  margin: 0.8em 0.4em 0.4em;
}
figcaption {
  font-style: italic;
  margin: 0 0 1em 0;
}
@media screen {
  pre {
    overflow-x: auto;
    max-width: 100%;
    max-width: calc(100% - 22px);
  }
}

/* aside, blockquote */
aside, blockquote {
  margin-left: 0;
  padding: 1.2em 2em;
}
blockquote {
  background-color: #f9f9f9;
  color: #111; /* Arlen: WCAG 2019 */
  border: 1px solid #ddd;
  border-radius: 3px;
  margin: 1em 0;
}
cite {
  display: block;
  text-align: right;
  font-style: italic;
}

/* tables */
table {
  width: 100%;
  margin: 0 0 1em;
  border-collapse: collapse;
  border: 1px solid #eee;
}
th, td {
  text-align: left;
  vertical-align: top;
  padding: 0.5em 0.75em;
}
th {
  text-align: left;
  background-color: #e9e9e9;
}
tr:nth-child(2n+1) > td {
  background-color: #f5f5f5;
}
table caption {
  font-style: italic;
  margin: 0;
  padding: 0;
  text-align: left;
}
table p {
  /* XXX to avoid bottom margin on table row signifiers. If paragraphs should
     be allowed within tables more generally, it would be far better to select on a class. */
  margin: 0;
}

/* pilcrow */
a.pilcrow {
  color: #666; /* Arlen: AHDJ 2019 */
  text-decoration: none;
  visibility: hidden;
  user-select: none;
  -ms-user-select: none;
  -o-user-select:none;
  -moz-user-select: none;
  -khtml-user-select: none;
  -webkit-user-select: none;
  -webkit-touch-callout: none;
}
@media screen {
  aside:hover > a.pilcrow,
  p:hover > a.pilcrow,
  blockquote:hover > a.pilcrow,
  div:hover > a.pilcrow,
  li:hover > a.pilcrow,
  pre:hover > a.pilcrow {
    visibility: visible;
  }
  a.pilcrow:hover {
    background-color: transparent;
  }
}

/* misc */
hr {
  border: 0;
  border-top: 1px solid #eee;
}
.bcp14 {
  font-variant: small-caps;
}

.role {
  font-variant: all-small-caps;
}

/* info block */
#identifiers {
  margin: 0;
  font-size: 0.9em;
}
#identifiers dt {
  width: 3em;
  clear: left;
}
#identifiers dd {
  float: left;
  margin-bottom: 0;
}
#identifiers .authors .author {
  display: inline-block;
  margin-right: 1.5em;
}
#identifiers .authors .org {
  font-style: italic;
}

/* The prepared/rendered info at the very bottom of the page */
.docInfo {
  color: #666; /* Arlen: WCAG 2019 */
  font-size: 0.9em;
  font-style: italic;
  margin-top: 2em;
}
.docInfo .prepared {
  float: left;
}
.docInfo .prepared {
  float: right;
}

/* table of contents */
#toc  {
  padding: 0.75em 0 2em 0;
  margin-bottom: 1em;
}
nav.toc ul {
  margin: 0 0.5em 0 0;
  padding: 0;
  list-style: none;
}
nav.toc li {
  line-height: 1.3em;
  margin: 0.75em 0;
  padding-left: 1.2em;
  text-indent: -1.2em;
}
/* references */
.references dt {
  text-align: right;
  font-weight: bold;
  min-width: 7em;
}
.references dd {
  margin-left: 8em;
  overflow: auto;
}

.refInstance {
  margin-bottom: 1.25em;
}

.references .ascii {
  margin-bottom: 0.25em;
}

/* index */
.index ul {
  margin: 0 0 0 1em;
  padding: 0;
  list-style: none;
}
.index ul ul {
  margin: 0;
}
.index li {
  margin: 0;
  text-indent: -2em;
  padding-left: 2em;
  padding-bottom: 5px;
}
.indexIndex {
  margin: 0.5em 0 1em;
}
.index a {
  font-weight: 700;
}
/* make the index two-column on all but the smallest screens */
@media (min-width: 600px) {
  .index ul {
    -moz-column-count: 2;
    -moz-column-gap: 20px;
  }
  .index ul ul {
    -moz-column-count: 1;
    -moz-column-gap: 0;
  }
}

/* authors */
address.vcard {
  font-style: normal;
  margin: 1em 0;
}

address.vcard .nameRole {
  font-weight: 700;
  margin-left: 0;
}
address.vcard .label {
  font-family: "Noto Sans",Arial,Helvetica,sans-serif;
  margin: 0.5em 0;
}
address.vcard .type {
  display: none;
}
.alternative-contact {
  margin: 1.5em 0 1em;
}
hr.addr {
  border-top: 1px dashed;
  margin: 0;
  color: #ddd;
  max-width: calc(100% - 16px);
}

/* temporary notes */
.rfcEditorRemove::before {
  position: absolute;
  top: 0.2em;
  right: 0.2em;
  padding: 0.2em;
  content: "The RFC Editor will remove this note";
  color: #9e2a00; /* Arlen: WCAG 2019 */
  background-color: #ffd; /* Arlen: WCAG 2019 */
}
.rfcEditorRemove {
  position: relative;
  padding-top: 1.8em;
  background-color: #ffd; /* Arlen: WCAG 2019 */
  border-radius: 3px;
}
.cref {
  background-color: #ffd; /* Arlen: WCAG 2019 */
  padding: 2px 4px;
}
.crefSource {
  font-style: italic;
}
/* alternative layout for smaller screens */
@media screen and (max-width: 1023px) {
  body {
    padding-top: 2em;
  }
  #title {
    padding: 1em 0;
  }
  h1 {
    font-size: 24px;
  }
  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;
    border-bottom: 1px solid #ccc;
  }
  #toc h2 {
    margin: -1px 0 0 0;
    padding: 4px 0 4px 6px;
    padding-right: 1em;
    min-width: 190px;
    font-size: 1.1em;
    text-align: right;
    background-color: #444;
    color: white;
    cursor: pointer;
  }
  #toc h2::before { /* css hamburger */
    float: right;
    position: relative;
    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 {
    display: none;
    padding: 0.5em 1em 1em;
    overflow: auto;
    height: calc(100vh - 48px);
    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 {
  body {

    width: 100%;
  }
  p {
    orphans: 3;
    widows: 3;
  }
  #n-copyright-notice {
    border-bottom: none;
  }
  #toc, #n-introduction {
    page-break-before: always;
  }
  #toc {
    border-top: none;
    padding-top: 0;
  }
  figure, pre {
    page-break-inside: avoid;
  }
  figure {
    overflow: scroll;
  }
  h1, h2, h3, h4, h5, h6 {
    page-break-after: avoid;
  }
  h2+*, h3+*, h4+*, h5+*, h6+* {
    page-break-before: avoid;
  }
  pre {
    white-space: pre-wrap;
    word-wrap: break-word;
    font-size: 10pt;
  }
  table {
    border: 1px solid #ddd;
  }
  td {
    border-top: 1px solid #ddd;
  }
}

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

.ears thead .center {
  string-set: ears-top-center content();
}

.ears thead .right {
  string-set: ears-top-right content();
}

.ears tfoot .left {
  string-set: ears-bottom-left content();
}

.ears tfoot .center {
  string-set: ears-bottom-center content();
}

.ears tfoot .right {
  string-set: ears-bottom-right content();
}
*/

@page :first {
  padding-top: 0;
  @top-left {
    content: normal;
    border: none;
  }
  @top-center {
    content: normal;
    border: none;
  }
  @top-right {
    content: normal;
    border: none;
  }
}

@page {
  size: A4;
  margin-bottom: 45mm;
  padding-top: 20px;
  /* The follwing is commented out here, but set appropriately by in code, as
     the content depends on the document */
  /*
  @top-left {
    content: 'Internet-Draft';
    vertical-align: bottom;
    border-bottom: solid 1px #ccc;
  }
  @top-left {
    content: string(ears-top-left);
    vertical-align: bottom;
    border-bottom: solid 1px #ccc;
  }
  @top-center {
    content: string(ears-top-center);
    vertical-align: bottom;
    border-bottom: solid 1px #ccc;
  }
  @top-right {
    content: string(ears-top-right);
    vertical-align: bottom;
    border-bottom: solid 1px #ccc;
  }
  @bottom-left {
    content: string(ears-bottom-left);
    vertical-align: top;
    border-top: solid 1px #ccc;
  }
  @bottom-center {
    content: string(ears-bottom-center);
    vertical-align: top;
    border-top: solid 1px #ccc;
  }
  @bottom-right {
      content: '[Page ' counter(page) ']';
      vertical-align: top;
      border-top: solid 1px #ccc;
  }
  */

}

/* 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 {
  padding-right: 0.5em;
}

/* prevent monospace from becoming overly large */
tt, code, pre, code {
  font-size: 95%;
}

/* 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;
  padding: 0.5em;
  margin-bottom: 0.5em;
  display: none;
}
div#internal-metadata {
  padding: 0.5em;                       /* to match the external-metadata padding */
}
/* Styling for title RFC Number */
h1#rfcnum {
  clear: both;
  margin: 0 0 -1em;
  padding: 1em 0 0 0;
}
/* Make .olPercent look the same as <ol><li> */
dl.olPercent > dd {
  margin-bottom: 0.25em;
  min-height: initial;
}
/* Give aside some styling to set it apart */
aside {
  border-left: 1px solid #ddd;
  margin: 1em 0 1em 2em;
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<table class="ears">
<thead><tr>
<td class="left">RFC 8892</td>
<td class="center">ifType Guidelines</td>
<td class="right">August 2020</td>
</tr></thead>
<tfoot><tr>
<td class="left">Thaler &amp; Romascanu</td>
<td class="center">Standards Track</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/rfc8892" class="eref">8892</a></dd>
<dt class="label-updates">Updates:</dt>
<dd class="updates">
<a href="https://www.rfc-editor.org/rfc/rfc2863" class="eref">2863</a> </dd>
<dt class="label-category">Category:</dt>
<dd class="category">Standards Track</dd>
<dt class="label-published">Published:</dt>
<dd class="published">
<time datetime="2020-08" class="published">August 2020</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">D. Thaler</div>
<div class="org">Microsoft</div>
</div>
<div class="author">
      <div class="author-name">D. Romascanu</div>
<div class="org">Independent</div>
</div>
</dd>
</dl>
</div>
<h1 id="rfcnum">RFC 8892</h1>
<h1 id="title">Guidelines and Registration Procedures for Interface Types and Tunnel Types</h1>
<section id="section-abstract">
      <h2 id="abstract"><a href="#abstract" class="selfRef">Abstract</a></h2>
<p id="section-abstract-1">This document provides guidelines and procedures for those who are defining, registering, 
or evaluating definitions of new interface types ("ifType" values) and tunnel types.
The original definition of the IANA interface type registry predated
the use of IANA Considerations sections and YANG modules, so some confusion arose
over time. Tunnel types were added later, with the same requirements and allocation policy as
interface types. This document updates RFC 2863 and provides updated guidance for
these registries.<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 is an Internet Standards Track document.<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).  Further
            information on Internet Standards is available in 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/rfc8892">https://www.rfc-editor.org/info/rfc8892</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) 2020 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="ulEmpty toc compact">
<li class="ulEmpty toc compact" 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="ulEmpty toc compact" 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="ulEmpty toc compact" 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-problems" class="xref">Problems</a><a href="#section-toc.1-1.3.1" class="pilcrow">¶</a></p>
</li>
          <li class="ulEmpty toc compact" 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-interface-sub-layers-and-su" class="xref">Interface Sub-layers and Sub-types</a><a href="#section-toc.1-1.4.1" class="pilcrow">¶</a></p>
<ul class="ulEmpty toc compact">
<li class="ulEmpty toc compact" 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-alternate-values" class="xref">Alternate Values</a><a href="#section-toc.1-1.4.2.1.1" class="pilcrow">¶</a></p>
</li>
            </ul>
</li>
          <li class="ulEmpty toc compact" 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-available-formats" class="xref">Available Formats</a><a href="#section-toc.1-1.5.1" class="pilcrow">¶</a></p>
</li>
          <li class="ulEmpty toc compact" 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-registration" class="xref">Registration</a><a href="#section-toc.1-1.6.1" class="pilcrow">¶</a></p>
<ul class="ulEmpty toc compact">
<li class="ulEmpty toc compact" 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-procedures" class="xref">Procedures</a><a href="#section-toc.1-1.6.2.1.1" class="pilcrow">¶</a></p>
</li>
              <li class="ulEmpty toc compact" 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-media-specific-oid-subtree-" class="xref">Media-Specific OID-Subtree Assignments</a><a href="#section-toc.1-1.6.2.2.1" class="pilcrow">¶</a></p>
</li>
              <li class="ulEmpty toc compact" 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-registration-template" class="xref">Registration Template</a><a href="#section-toc.1-1.6.2.3.1" class="pilcrow">¶</a></p>
<ul class="ulEmpty toc compact">
<li class="ulEmpty toc compact" id="section-toc.1-1.6.2.3.2.1">
                    <p id="section-toc.1-1.6.2.3.2.1.1"><a href="#section-6.3.1" class="xref">6.3.1</a>.  <a href="#name-iftype" class="xref">ifType</a><a href="#section-toc.1-1.6.2.3.2.1.1" class="pilcrow">¶</a></p>
</li>
                  <li class="ulEmpty toc compact" id="section-toc.1-1.6.2.3.2.2">
                    <p id="section-toc.1-1.6.2.3.2.2.1"><a href="#section-6.3.2" class="xref">6.3.2</a>.  <a href="#name-tunneltype" class="xref">tunnelType</a><a href="#section-toc.1-1.6.2.3.2.2.1" class="pilcrow">¶</a></p>
</li>
                </ul>
</li>
            </ul>
</li>
          <li class="ulEmpty toc compact" 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-iana-considerations" class="xref">IANA Considerations</a><a href="#section-toc.1-1.7.1" class="pilcrow">¶</a></p>
<ul class="ulEmpty toc compact">
<li class="ulEmpty toc compact" id="section-toc.1-1.7.2.1">
                <p id="section-toc.1-1.7.2.1.1"><a href="#section-7.1" class="xref">7.1</a>.  <a href="#name-mib-and-yang-modules" class="xref">MIB and YANG Modules</a><a href="#section-toc.1-1.7.2.1.1" class="pilcrow">¶</a></p>
</li>
              <li class="ulEmpty toc compact" id="section-toc.1-1.7.2.2">
                <p id="section-toc.1-1.7.2.2.1"><a href="#section-7.2" class="xref">7.2</a>.  <a href="#name-transmission-number-assignm" class="xref">Transmission Number Assignments</a><a href="#section-toc.1-1.7.2.2.1" class="pilcrow">¶</a></p>
</li>
            </ul>
</li>
          <li class="ulEmpty toc compact" 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="ulEmpty toc compact" 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-references" class="xref">References</a><a href="#section-toc.1-1.9.1" class="pilcrow">¶</a></p>
<ul class="ulEmpty toc compact">
<li class="ulEmpty toc compact" id="section-toc.1-1.9.2.1">
                <p id="section-toc.1-1.9.2.1.1"><a href="#section-9.1" class="xref">9.1</a>.  <a href="#name-normative-references" class="xref">Normative References</a><a href="#section-toc.1-1.9.2.1.1" class="pilcrow">¶</a></p>
</li>
              <li class="ulEmpty toc compact" id="section-toc.1-1.9.2.2">
                <p id="section-toc.1-1.9.2.2.1"><a href="#section-9.2" class="xref">9.2</a>.  <a href="#name-informative-references" class="xref">Informative References</a><a href="#section-toc.1-1.9.2.2.1" class="pilcrow">¶</a></p>
</li>
            </ul>
</li>
          <li class="ulEmpty toc compact" id="section-toc.1-1.10">
            <p id="section-toc.1-1.10.1"><a href="#section-appendix.a" class="xref"></a><a href="#name-authors-addresses" class="xref">Authors' Addresses</a><a href="#section-toc.1-1.10.1" class="pilcrow">¶</a></p>
</li>
        </ul>
</nav>
</section>
</div>
<div id="intro">
<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">The IANA IfType-MIB, which contains the list of interface type (ifType) values,
was originally defined in <span>[<a href="#RFC1573" class="xref">RFC1573</a>]</span> as a separate MIB
module together with the Interfaces Group MIB (IF-MIB) module.  The IF-MIB module was
subsequently updated and is currently specified in <span>[<a href="#RFC2863" class="xref">RFC2863</a>]</span>, but the latest IF-MIB
RFC no longer contains the IANA IfType-MIB. Instead, the IANA IfType-MIB is
maintained by IANA as a separate module.  Similarly, <span>[<a href="#RFC7224" class="xref">RFC7224</a>]</span> created an initial
IANA Interface Type YANG Module, and the current version is maintained by IANA.<a href="#section-1-1" class="pilcrow">¶</a></p>
<p id="section-1-2">The current IANA IfType registry is at <span>[<a href="#ifType-registry" class="xref">ifType-registry</a>]</span>, with the same values also
appearing in both <span>[<a href="#yang-if-type" class="xref">yang-if-type</a>]</span> and the
      IANAifType textual convention at <span>[<a href="#IANAifType-MIB" class="xref">IANAifType-MIB</a>]</span>.<a href="#section-1-2" class="pilcrow">¶</a></p>
<p id="section-1-3">Although the ifType registry was originally defined in a MIB module,
the assignment and use of interface type values are not tied to MIB modules
or any other management mechanism.  An interface type value can be used
as the value of a data model object (MIB object, YANG object, etc.),
as part of a unique identifier of a data model for a given
interface type (e.g., in an OID), or simply as a value exposed by local
APIs or UIs on a device.<a href="#section-1-3" class="pilcrow">¶</a></p>
<p id="section-1-4">The TUNNEL-MIB was defined in <span>[<a href="#RFC2667" class="xref">RFC2667</a>]</span> (now obsoleted by <span>[<a href="#RFC4087" class="xref">RFC4087</a>]</span>),
which created a tunnelType registry (<span>[<a href="#tunnelType-registry" class="xref">tunnelType-registry</a>]</span> and the IANAtunnelType textual
convention at <span>[<a href="#IANAifType-MIB" class="xref">IANAifType-MIB</a>]</span>), and it
defined the assignment policy for tunnelType values to always be identical to the policy for assigning
      ifType values.<a href="#section-1-4" class="pilcrow">¶</a></p>
</section>
</div>
<div id="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 key words "<span class="bcp14">MUST</span>", "<span class="bcp14">MUST NOT</span>", "<span class="bcp14">REQUIRED</span>", "<span class="bcp14">SHALL</span>", "<span class="bcp14">SHALL NOT</span>",
"<span class="bcp14">SHOULD</span>", "<span class="bcp14">SHOULD NOT</span>", "<span class="bcp14">RECOMMENDED</span>", "<span class="bcp14">NOT RECOMMENDED</span>", "<span class="bcp14">MAY</span>",
and "<span class="bcp14">OPTIONAL</span>" in this document are to be interpreted as described
in BCP 14 <span>[<a href="#RFC2119" class="xref">RFC2119</a>]</span> <span>[<a href="#RFC8174" class="xref">RFC8174</a>]</span> when, and only when, they appear
in all capitals, as shown here.<a href="#section-2-1" class="pilcrow">¶</a></p>
</section>
</div>
<div id="problems">
<section id="section-3">
      <h2 id="name-problems">
<a href="#section-3" class="section-number selfRef">3. </a><a href="#name-problems" class="section-name selfRef">Problems</a>
      </h2>
<p id="section-3-1">This document addresses the following issues:<a href="#section-3-1" class="pilcrow">¶</a></p>
<ol start="1" type="1" class="normal type-1" id="section-3-2">
        <li id="section-3-2.1">As noted in <a href="#intro" class="xref">Section 1</a>, the original guidance was written with wording
specific to MIB modules; accordingly, some confusion has resulted
when using YANG modules.  This document clarifies that ifTypes and tunnelTypes are
independent from the type of, or even existence of, a data model.<a href="#section-3-2.1" class="pilcrow">¶</a>
</li>
        <li id="section-3-2.2">The use of and requirements around sub-layers and sub-types
were not well understood, but good examples of both now exist.
This is discussed in <a href="#sublayers" class="xref">Section 4</a>.<a href="#section-3-2.2" class="pilcrow">¶</a>
</li>
        <li id="section-3-2.3">Since the "Interface Types (ifType)" and "Tunnel Types
 (tunnelType)" registries were originally defined, and are
still retrievable, in the format of MIB modules (in addition to other formats),
confusion arose when adding YANG modules as another format as to whether
each is a separate registry.  This is discussed in <a href="#formats" class="xref">Section 5</a>.<a href="#section-3-2.3" class="pilcrow">¶</a>
</li>
        <li id="section-3-2.4">The registries are retrievable in the format of MIB and YANG modules, but
there was previously no process guidance written to check that those formats were
syntactically correct as updates were made, which led to the registry having syntax errors
that broke tools.  <a href="#procedures" class="xref">Section 6.1</a> adds a validation step to the
documented assignment procedure.<a href="#section-3-2.4" class="pilcrow">¶</a>
</li>
        <li id="section-3-2.5">Various documents and registries previously said to submit requests via email,
but a web form exists for submitting requests, which caused
some confusion around which was to be used.  This is addressed
in <a href="#procedures" class="xref">Section 6.1</a>.<a href="#section-3-2.5" class="pilcrow">¶</a>
</li>
        <li id="section-3-2.6">Transmission values <span>[<a href="#transmission-registry" class="xref">transmission-registry</a>]</span> have generally been allocated as part
of ifType allocation, but no guidance existed as to whether a requester
must ask for it or not, and the request form had no such required field.
As a result, IANA has asked the designated expert to decide for each
allocation, but no relevant guidance for the designated expert has been
documented. This is remedied in <a href="#transmission-discussion" class="xref">Section 6.2</a>.<a href="#section-3-2.6" class="pilcrow">¶</a>
</li>
      </ol>
</section>
</div>
<div id="sublayers">
<section id="section-4">
      <h2 id="name-interface-sub-layers-and-su">
<a href="#section-4" class="section-number selfRef">4. </a><a href="#name-interface-sub-layers-and-su" class="section-name selfRef">Interface Sub-layers and Sub-types</a>
      </h2>
<p id="section-4-1">When multiple sub-layers exist below the network layer,
each sub-layer can be represented by its own
row in the ifTable with its own ifType, with the ifStackTable being used to identify the
upward and downward multiplexing relationships between rows. <span><a href="https://www.rfc-editor.org/rfc/rfc2863#section-3.1.1" class="relref">Section 3.1.1</a> of [<a href="#RFC2863" class="xref">RFC2863</a>]</span> provides more
discussion, and <a href="https://www.rfc-editor.org/rfc/rfc2863#section-3.1.2" class="relref">3.1.2</a> provides guidance for defining interface
sub-layers. More recent experience shows that those guidelines were
phrased in a way that is now too restrictive, since at the time
<span>[<a href="#RFC2863" class="xref">RFC2863</a>]</span> was written, MIB modules were the dominant data model.<a href="#section-4-1" class="pilcrow">¶</a></p>
<p id="section-4-2">This document clarifies that the same guidance also applies to YANG
      modules.<a href="#section-4-2" class="pilcrow">¶</a></p>
<p id="section-4-3">Some ifTypes may define sub-types.  For example, the tunnel(131)
      ifType defines sub-types known as "tunnelTypes", where each tunnelType can have its own MIB and/or YANG
module with protocol-specific information, but there is enough in common
that some information is exposed in a generic IP Tunnel MIB corresponding
to the tunnel(131) ifType.<a href="#section-4-3" class="pilcrow">¶</a></p>
<p id="section-4-4">For requests that involve multiple sub-layers below the network layer,
requests <span class="bcp14">MUST</span> include (or reference) a discussion of the multiplexing relationships
between sub-layers, ideally with a diagram. Various well-written examples exist of
such definitions, including <span><a href="https://www.rfc-editor.org/rfc/rfc3637#section-3.4.1" class="relref">Section 3.4.1</a> of [<a href="#RFC3637" class="xref">RFC3637</a>]</span>, <span><a href="https://www.rfc-editor.org/rfc/rfc4087#section-3.1.1" class="relref">Section 3.1.1</a> of [<a href="#RFC4087" class="xref">RFC4087</a>]</span>,
and <span><a href="https://www.rfc-editor.org/rfc/rfc5066#section-3.1.1" class="relref">Section 3.1.1</a> of [<a href="#RFC5066" class="xref">RFC5066</a>]</span>.<a href="#section-4-4" class="pilcrow">¶</a></p>
<p id="section-4-5">Definers of sub-layers and sub-types should consider which model is more
appropriate for their needs. A sub-layer is generally used whenever either a
dynamic relationship exists (i.e., when the set of instances above or below a
given instance can change over time) or a multiplexing relationship exists
with another sub-layer. A sub-type can be used when neither of these is true
but where one interface type is conceptually a subclass of another interface type, as far
as a management data model is concerned.<a href="#section-4-5" class="pilcrow">¶</a></p>
<p id="section-4-6">In general, the intent of an interface type or sub-type is that its definition should
be sufficient to identify an interoperable protocol.   In some cases, however,
a protocol might be defined in a way that is not sufficient to provide
interoperability with other compliant implementations of that protocol.
In such a case, an ifType definition should discuss whether specific
instantiations (or profiles) of behavior should use a sub-layer model
(e.g., each vendor might layer the protocol over its own sub-layer
that provides the missing details) or a sub-type model (i.e., each
vendor might subclass the protocol without any layering relationship).
If a sub-type model is more appropriate, then the data model for the
protocol might include a sub-type identifier so that management software
can discover objects specific to the sub-type.  In either case, such
discussion is important to guide definers of a data model for the more
specific information (i.e., a lower sub-layer or a sub-type), as well
as the designated expert, who must review requests for any such
ifTypes or sub-types.<a href="#section-4-6" class="pilcrow">¶</a></p>
<div id="alternate-values">
<section id="section-4.1">
        <h3 id="name-alternate-values">
<a href="#section-4.1" class="section-number selfRef">4.1. </a><a href="#name-alternate-values" class="section-name selfRef">Alternate Values</a>
        </h3>
<p id="section-4.1-1">Another design decision is whether to reuse an existing ifType or tunnelType
value, possibly using a sub-type or sub-layer model for refinements, or
to use a different value for a new mechanism.<a href="#section-4.1-1" class="pilcrow">¶</a></p>
<p id="section-4.1-2">If there is already an entry that could easily satisfy the modeling and functional
requirements for the requested entry, it should be reused so that
applications and tools that use the existing value can be used without changes.
If, however, the modeling and functional requirements are significantly different
enough such that having existing applications and tools use the existing value
would be seen as a problem, a new value should be used.<a href="#section-4.1-2" class="pilcrow">¶</a></p>
<p id="section-4.1-3">For example, originally different ifType values were used for different
flavors of Ethernet (ethernetCsmacd(6), iso88023Csmacd(7), fastEther(62), etc.),
typically because they were registered by different vendors. Using different values
was, however, seen as problematic because all were functionally similar, so <span>[<a href="#RFC3635" class="xref">RFC3635</a>]</span> then deprecated all but
 ethernetCsmacd(6).<a href="#section-4.1-3" class="pilcrow">¶</a></p>
<p id="section-4.1-4">As another example, a udp(8) tunnelType value was defined in <span>[<a href="#RFC2667" class="xref">RFC2667</a>]</span>
with the description "The value UDP indicates that the payload packet is 
encapsulated within a normal UDP packet (e.g., RFC 1234)." The Teredo tunnel
protocol <span>[<a href="#RFC4380" class="xref">RFC4380</a>]</span> was later defined and encapsulates packets over UDP, but the
protocol model is quite different between <span>[<a href="#RFC1234" class="xref">RFC1234</a>]</span> and Teredo.  For
example, <span>[<a href="#RFC1234" class="xref">RFC1234</a>]</span> supports encapsulation of multicast/broadcast traffic,
whereas Teredo does not.  As such, it would be more confusing to applications
and tools to represent them using the same tunnel type, and so <span>[<a href="#RFC4087" class="xref">RFC4087</a>]</span>
defined a new value for Teredo.<a href="#section-4.1-4" class="pilcrow">¶</a></p>
<p id="section-4.1-5">In summary, definers of new interface or tunnel mechanisms should use a new ifType or
tunnelType value rather than reuse an existing value when key aspects such
as the header format or the link model (point-to-point, non-broadcast multi-access,
broadcast-capable multi-access, unidirectional broadcast, etc.) are significantly 
different from existing values, but they should reuse the same value when the differences
can be expressed in terms of differing values of existing objects other than 
ifType/tunnelType in the standard YANG or MIB module.<a href="#section-4.1-5" class="pilcrow">¶</a></p>
</section>
</div>
</section>
</div>
<div id="formats">
<section id="section-5">
      <h2 id="name-available-formats">
<a href="#section-5" class="section-number selfRef">5. </a><a href="#name-available-formats" class="section-name selfRef">Available Formats</a>
      </h2>
<p id="section-5-1">Many registries are available in multiple formats.  For example,
XML, HTML, CSV, and plain text are common formats in which many registries
are available.  This document clarifies that the <span>[<a href="#IANAifType-MIB" class="xref">IANAifType-MIB</a>]</span>,
<span>[<a href="#yang-if-type" class="xref">yang-if-type</a>]</span>, and <span>[<a href="#yang-tunnel-type" class="xref">yang-tunnel-type</a>]</span> MIB and YANG modules
are merely additional formats in which the "Interface Types (ifType)" and "Tunnel Types (tunnelType)"
registries are available.  The MIB and YANG modules are not separate registries, and the same
values are always present in all formats of the same registry.<a href="#section-5-1" class="pilcrow">¶</a></p>
<p id="section-5-2">The confusion stemmed in part from the fact that the IANA "Protocol Registries"
<span>[<a href="#protocol-registries" class="xref">protocol-registries</a>]</span> listed the YANG and MIB module formats separately,
as if they were separate registries. However, the entries for the
yang-if-type and iana-tunnel-type YANG modules said "See ifType definitions registry"
and "See tunnelType registry (mib-2.interface.ifTable.ifEntry.ifType.tunnelType)"
respectively, although the entry for the IANAifType-MIB had no such note.
<a href="#module-formats" class="xref">Section 7.1</a> addresses this.<a href="#section-5-2" class="pilcrow">¶</a></p>
</section>
</div>
<div id="registration">
<section id="section-6">
      <h2 id="name-registration">
<a href="#section-6" class="section-number selfRef">6. </a><a href="#name-registration" class="section-name selfRef">Registration</a>
      </h2>
<p id="section-6-1">The IANA policy (using terms defined in <span>[<a href="#RFC8126" class="xref">RFC8126</a>]</span>) for registration is
Expert Review for both interface types and tunnel types.  The role of the 
designated expert in the procedure is to
raise possible concerns about wider implications of proposals for use and
deployment of interface types.  While it is recommended that the responsible
Area Director and the IESG take into consideration the designated
expert opinions, nothing in the procedure empowers the
designated expert to override properly arrived-at IETF or working group
consensus.<a href="#section-6-1" class="pilcrow">¶</a></p>
<div id="procedures">
<section id="section-6.1">
        <h3 id="name-procedures">
<a href="#section-6.1" class="section-number selfRef">6.1. </a><a href="#name-procedures" class="section-name selfRef">Procedures</a>
        </h3>
<p id="section-6.1-1">Someone wishing to register a new ifType or tunnelType value <span class="bcp14">MUST</span>:<a href="#section-6.1-1" class="pilcrow">¶</a></p>
<ol start="1" type="1" class="normal type-1" id="section-6.1-2">
          <li id="section-6.1-2.1">Check the IANA registry to see whether there is already an entry that could
easily satisfy the modeling and functional requirements for the requested entry.
If there is already such an entry, use it or update the existing specification.
Text in an Internet-Draft or part of some permanently
available, stable specification may be written to clarify the usage of an
existing entry or entries for the desired purpose.<a href="#section-6.1-2.1" class="pilcrow">¶</a>
</li>
          <li id="section-6.1-2.2">Check the IANA registry to see whether there is already some other entry with
the desired name.  If there is already an unrelated entry under the desired name, choose
a different name.<a href="#section-6.1-2.2" class="pilcrow">¶</a>
</li>
          <li id="section-6.1-2.3">Prepare a registration request using the template specified in <a href="#template" class="xref">Section 6.3</a>.
The registration request can be contained in an Internet-Draft, submitted
alone, or submitted as part of some permanently available, stable specification. The registration request can also be submitted in some
other form (as part of another document or as a stand-alone document),
but the registration request will be treated as an "IETF Contribution"
under the guidelines of <span>[<a href="#RFC5378" class="xref">RFC5378</a>]</span>.<a href="#section-6.1-2.3" class="pilcrow">¶</a>
</li>
          <li id="section-6.1-2.4">Submit the registration request (or pointer to a document containing it)
to IANA at iana@iana.org or (if requesting an ifType) via the web form
at <span>&lt;<a href="https://www.iana.org/form/iftype">https://www.iana.org/form/iftype</a>&gt;</span>.<a href="#section-6.1-2.4" class="pilcrow">¶</a>
</li>
        </ol>
<p id="section-6.1-3">Upon receipt of a registration request, the following steps <span class="bcp14">MUST</span> be followed:<a href="#section-6.1-3" class="pilcrow">¶</a></p>
<ol start="1" type="1" class="normal type-1" id="section-6.1-4">
          <li id="section-6.1-4.1">IANA checks the submission for completeness; if required information is
missing or any citations are not correct, IANA will reject the registration
request.  A registrant can resubmit a corrected request if desired.<a href="#section-6.1-4.1" class="pilcrow">¶</a>
</li>
          <li id="section-6.1-4.2">IANA requests Expert Review of the registration request against the
corresponding guidelines from this document.<a href="#section-6.1-4.2" class="pilcrow">¶</a>
</li>
          <li id="section-6.1-4.3">The designated expert will evaluate the request against the criteria.<a href="#section-6.1-4.3" class="pilcrow">¶</a>
</li>
          <li id="section-6.1-4.4">Once the designated expert approves a registration, IANA updates <span>[<a href="#ifType-registry" class="xref">ifType-registry</a>]</span>,
<span>[<a href="#IANAifType-MIB" class="xref">IANAifType-MIB</a>]</span>, and <span>[<a href="#yang-if-type" class="xref">yang-if-type</a>]</span> to show the registration for an interface type,
or <span>[<a href="#tunnelType-registry" class="xref">tunnelType-registry</a>]</span>, <span>[<a href="#IANAifType-MIB" class="xref">IANAifType-MIB</a>]</span>, and <span>[<a href="#yang-tunnel-type" class="xref">yang-tunnel-type</a>]</span> to show the registration
for a tunnel type.
When adding values, IANA should verify that the updated
MIB module and YANG module formats are syntactically correct before publishing the update.  There are
various existing tools or websites that can be used to do this verification.<a href="#section-6.1-4.4" class="pilcrow">¶</a>
</li>
          <li id="section-6.1-4.5">If instead the designated expert
does not approve registration (e.g., for any of the reasons in
<span>[<a href="#RFC8126" class="xref">RFC8126</a>], <a href="https://www.rfc-editor.org/rfc/rfc8126#section-5" class="relref">Section 5</a></span>), a registrant can resubmit a corrected request
if desired, or the IESG can override the designated expert and approve
it per the process in <span><a href="https://www.rfc-editor.org/rfc/rfc8126#section-3.3" class="relref">Section 3.3</a> of [<a href="#RFC8126" class="xref">RFC8126</a>]</span>.<a href="#section-6.1-4.5" class="pilcrow">¶</a>
</li>
        </ol>
</section>
</div>
<div id="transmission-discussion">
<section id="section-6.2">
        <h3 id="name-media-specific-oid-subtree-">
<a href="#section-6.2" class="section-number selfRef">6.2. </a><a href="#name-media-specific-oid-subtree-" class="section-name selfRef">Media-Specific OID-Subtree Assignments</a>
        </h3>
<p id="section-6.2-1"><span>[<a href="#IANAifType-MIB" class="xref">IANAifType-MIB</a>]</span> notes:<a href="#section-6.2-1" class="pilcrow">¶</a></p>
<blockquote id="section-6.2-2">The relationship between the assignment of ifType
  values and of OIDs to particular media-specific MIBs
  is solely the purview of IANA and is subject to change
  without notice.  Quite often, a media-specific MIB's
  OID-subtree assignment within MIB-II's 'transmission'
  subtree will be the same as its ifType value.
  However, in some circumstances this will not be the
  case, and implementors must not pre-assume any
  specific relationship between ifType values and
  transmission subtree OIDs.<a href="#section-6.2-2" class="pilcrow">¶</a>
</blockquote>
<p id="section-6.2-3">The advice above remains unchanged, but this document changes the allocation procedure
to streamline the process, so that an ifType value and a transmission number value
with the same value will be assigned at the same time.<a href="#section-6.2-3" class="pilcrow">¶</a></p>
<p id="section-6.2-4">Rationale:<a href="#section-6.2-4" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="olPercent" id="section-6.2-5">
          <dt>(1)</dt>
<dd id="section-6.2-5.1"> This saves future effort if a
transmission number is later deemed necessary, since no IANA request is
needed that would then require another Expert Review.<a href="#section-6.2-5.1" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt>(2)</dt>
<dd id="section-6.2-5.2">The transmission numbering space is not scarce, so there seems to be little need to reserve the number for a different purpose than what the ifType
is for.<a href="#section-6.2-5.2" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt>(3)</dt>
<dd id="section-6.2-5.3">The designated expert need not review whether a transmission
number value should be registered when processing each ifType request, thus
reducing the possibility of delaying assignment of ifType values.<a href="#section-6.2-5.3" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
<dt>(4)</dt>
<dd id="section-6.2-5.4">There is no case on record where allocating the same value could have
caused any problems.<a href="#section-6.2-5.4" class="pilcrow">¶</a>
</dd>
        <dd class="break"></dd>
</dl>
</section>
</div>
<div id="template">
<section id="section-6.3">
        <h3 id="name-registration-template">
<a href="#section-6.3" class="section-number selfRef">6.3. </a><a href="#name-registration-template" class="section-name selfRef">Registration Template</a>
        </h3>
<div id="iftype-template">
<section id="section-6.3.1">
          <h4 id="name-iftype">
<a href="#section-6.3.1" class="section-number selfRef">6.3.1. </a><a href="#name-iftype" class="section-name selfRef">ifType</a>
          </h4>
<p id="section-6.3.1-1">The following template describes the fields that <span class="bcp14">MUST</span> be supplied in a registration request
suitable for adding to the "Interface Types (ifType)" registry:<a href="#section-6.3.1-1" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-6.3.1-2">
            <dt id="section-6.3.1-2.1">Label for IANA ifType requested:</dt>
            <dd id="section-6.3.1-2.2">
  As explained in <span><a href="https://www.rfc-editor.org/rfc/rfc2578#section-7.1.1" class="relref">Section 7.1.1</a> of [<a href="#RFC2578" class="xref">RFC2578</a>]</span>, a label for a named-number enumeration
must consist of one or more letters or digits, up to a maximum of 64 characters, and 
the initial character must be a lowercase letter. (However, labels longer than 32 
characters are not recommended.) Note that hyphens are not allowed.<a href="#section-6.3.1-2.2" class="pilcrow">¶</a>
</dd>
            <dd class="break"></dd>
<dt id="section-6.3.1-2.3">Name of IANA ifType requested:</dt>
            <dd id="section-6.3.1-2.4">
  A short description (e.g., a protocol name) suitable to appear in a comment in the registry.<a href="#section-6.3.1-2.4" class="pilcrow">¶</a>
</dd>
            <dd class="break"></dd>
<dt id="section-6.3.1-2.5">Description of the proposed use of the IANA ifType:</dt>
            <dd id="section-6.3.1-2.6">
              <p id="section-6.3.1-2.6.1">
  Requesters <span class="bcp14">MUST</span> include answers, either directly or via a link to a document
with the answers, to the following questions in the explanation
of the proposed use of the IANA IfType:<a href="#section-6.3.1-2.6.1" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-6.3.1-2.6.2.1">How would IP run over your ifType?<a href="#section-6.3.1-2.6.2.1" class="pilcrow">¶</a>
</li>
                <li class="normal" id="section-6.3.1-2.6.2.2">Would there be another interface sub-layer between your
 ifType and IP?<a href="#section-6.3.1-2.6.2.2" class="pilcrow">¶</a>
</li>
                <li class="normal" id="section-6.3.1-2.6.2.3">Would your ifType be vendor specific / proprietary? (If so, the label
<span class="bcp14">MUST</span> start with a string that shows that. For example, if your company's
name or acronym is xxx, then the ifType label would be something like
xxxSomeIfTypeLabel.)<a href="#section-6.3.1-2.6.2.3" class="pilcrow">¶</a>
</li>
                <li class="normal" id="section-6.3.1-2.6.2.4">Would your ifType require or allow vendor-specific extensions?  If so,
would the vendor use their own ifType in a sub-layer below the requested ifType,
a sub-type of the ifType, or some other mechanism?<a href="#section-6.3.1-2.6.2.4" class="pilcrow">¶</a>
</li>
              </ul>
</dd>
            <dd class="break"></dd>
<dt id="section-6.3.1-2.7">Reference, Internet-Draft, or Specification:</dt>
            <dd id="section-6.3.1-2.8">
  A link to a document is required.<a href="#section-6.3.1-2.8" class="pilcrow">¶</a>
</dd>
            <dd class="break"></dd>
<dt id="section-6.3.1-2.9">Additional information or comments:</dt>
            <dd id="section-6.3.1-2.10">
  Optional; any additional comments for IANA or the designated expert.<a href="#section-6.3.1-2.10" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
</dl>
</section>
</div>
<div id="tunneltype-template">
<section id="section-6.3.2">
          <h4 id="name-tunneltype">
<a href="#section-6.3.2" class="section-number selfRef">6.3.2. </a><a href="#name-tunneltype" class="section-name selfRef">tunnelType</a>
          </h4>
<p id="section-6.3.2-1">Prior to this document, no form existed for tunnelType (and new tunnelType requests did not
need to use the ifType form that did exist). This document therefore specifies a tunnelType
form.<a href="#section-6.3.2-1" class="pilcrow">¶</a></p>
<p id="section-6.3.2-2">The following template describes the fields that <span class="bcp14">MUST</span> be supplied in a 
registration request suitable for adding to the "Tunnel Types (tunnelType)" registry:<a href="#section-6.3.2-2" class="pilcrow">¶</a></p>
<span class="break"></span><dl class="dlParallel" id="section-6.3.2-3">
            <dt id="section-6.3.2-3.1">Label for IANA tunnelType requested:</dt>
            <dd id="section-6.3.2-3.2">
  As explained in <span><a href="https://www.rfc-editor.org/rfc/rfc2578#section-7.1.1" class="relref">Section 7.1.1</a> of [<a href="#RFC2578" class="xref">RFC2578</a>]</span>, a label for a named-number enumeration
must consist of one or more letters or digits, up to a maximum of 64 characters, and
the initial character must be a lowercase letter. (However, labels longer than 32
characters are not recommended.) Note that hyphens are not allowed.<a href="#section-6.3.2-3.2" class="pilcrow">¶</a>
</dd>
            <dd class="break"></dd>
<dt id="section-6.3.2-3.3">Name of IANA tunnelType requested:</dt>
            <dd id="section-6.3.2-3.4">
  A short description (e.g., a protocol name) suitable to appear in a comment in the registry.<a href="#section-6.3.2-3.4" class="pilcrow">¶</a>
</dd>
            <dd class="break"></dd>
<dt id="section-6.3.2-3.5">Description of the proposed use of the IANA tunnelType:</dt>
            <dd id="section-6.3.2-3.6">
              <p id="section-6.3.2-3.6.1">
  Requesters <span class="bcp14">MUST</span> include answers, either directly or via a link to a document
with the answers, to the following questions in the explanation
of the proposed use of the IANA tunnelType:<a href="#section-6.3.2-3.6.1" class="pilcrow">¶</a></p>
<ul class="normal">
<li class="normal" id="section-6.3.2-3.6.2.1">How would IP run over your tunnelType?<a href="#section-6.3.2-3.6.2.1" class="pilcrow">¶</a>
</li>
                <li class="normal" id="section-6.3.2-3.6.2.2">Would there be another interface sub-layer between your tunnelType and IP?<a href="#section-6.3.2-3.6.2.2" class="pilcrow">¶</a>
</li>
                <li class="normal" id="section-6.3.2-3.6.2.3">Would your tunnelType be vendor-specific or proprietary? (If so, the label
<span class="bcp14">MUST</span> start with a string that shows that. For example, if your company's
name or acronym is xxx, then the tunnelType label would be something like
xxxSomeTunnelTypeLabel.)<a href="#section-6.3.2-3.6.2.3" class="pilcrow">¶</a>
</li>
                <li class="normal" id="section-6.3.2-3.6.2.4">Would your tunnelType require or allow vendor-specific extensions?  If so,
would the vendor use their own tunnelType in a sub-layer below the requested tunnelType,
or some sort of sub-type of the tunnelType, or some other mechanism?<a href="#section-6.3.2-3.6.2.4" class="pilcrow">¶</a>
</li>
              </ul>
</dd>
            <dd class="break"></dd>
<dt id="section-6.3.2-3.7">Reference, Internet-Draft, or Specification:</dt>
            <dd id="section-6.3.2-3.8">
  A link to a document is required.<a href="#section-6.3.2-3.8" class="pilcrow">¶</a>
</dd>
            <dd class="break"></dd>
<dt id="section-6.3.2-3.9">Additional information or comments:</dt>
            <dd id="section-6.3.2-3.10">
  Optionally any additional comments for IANA or the designated expert.<a href="#section-6.3.2-3.10" class="pilcrow">¶</a>
</dd>
          <dd class="break"></dd>
</dl>
</section>
</div>
</section>
</div>
</section>
</div>
<div id="iana-considerations">
<section id="section-7">
      <h2 id="name-iana-considerations">
<a href="#section-7" class="section-number selfRef">7. </a><a href="#name-iana-considerations" class="section-name selfRef">IANA Considerations</a>
      </h2>
<p id="section-7-1">This entire document is about IANA considerations, but this section
      discusses actions taken by and to be taken by IANA. 
There are three registries affected:<a href="#section-7-1" class="pilcrow">¶</a></p>
<ol start="1" type="1" class="normal type-1" id="section-7-2">
        <li id="section-7-2.1">Interface Types (ifType) <span>[<a href="#ifType-registry" class="xref">ifType-registry</a>]</span>: The registration process
 is updated in <a href="#procedures" class="xref">Section 6.1</a>, and the template is updated in <a href="#iftype-template" class="xref">Section 6.3.1</a>.<a href="#section-7-2.1" class="pilcrow">¶</a>
</li>
        <li id="section-7-2.2">Tunnel Types (tunnelType) <span>[<a href="#tunnelType-registry" class="xref">tunnelType-registry</a>]</span>: The registration
 process is updated in <a href="#procedures" class="xref">Section 6.1</a>, and the template is updated in <a href="#tunneltype-template" class="xref">Section 6.3.2</a>.<a href="#section-7-2.2" class="pilcrow">¶</a>
</li>
        <li id="section-7-2.3">Transmission Number Values <span>[<a href="#transmission-registry" class="xref">transmission-registry</a>]</span>: 
 The assignment process is updated in <a href="#transmission-discussion" class="xref">Section 6.2</a>.<a href="#section-7-2.3" class="pilcrow">¶</a>
</li>
      </ol>
<p id="section-7-3">At the time of publication of this document, IANA is unable to
perform some of the actions requested below due to limitations of their current
platform and toolset. In such cases, IANA is requested to perform these actions
as and when the migration to a new platform that would enable 
these actions is complete.<a href="#section-7-3" class="pilcrow">¶</a></p>
<div id="module-formats">
<section id="section-7.1">
        <h3 id="name-mib-and-yang-modules">
<a href="#section-7.1" class="section-number selfRef">7.1. </a><a href="#name-mib-and-yang-modules" class="section-name selfRef">MIB and YANG Modules</a>
        </h3>
<p id="section-7.1-1">
   IANA is to complete the following to clarify the relationship
   between MIB modules, YANG modules, and the relevant registries.<a href="#section-7.1-1" class="pilcrow">¶</a></p>
<ol start="1" type="1" class="normal type-1" id="section-7.1-2">
          <li id="section-7.1-2.1">
            <p id="section-7.1-2.1.1">The following note has been added to the IANAifType-MIB at
   <span>[<a href="#protocol-registries" class="xref">protocol-registries</a>]</span>: 
          "This is one of the available formats of the Interface Types
   (ifType) and Tunnel Types (tunnelType) registries."<a href="#section-7.1-2.1.1" class="pilcrow">¶</a></p>
</li>
          <li id="section-7.1-2.2">
            <p id="section-7.1-2.2.1">The note for the iana-if-type YANG module 
   at <span>[<a href="#protocol-registries" class="xref">protocol-registries</a>]</span> has been
   updated to read:
   "This is one of the available formats of the Interface Types (ifType) registry."<a href="#section-7.1-2.2.1" class="pilcrow">¶</a></p>
</li>
          <li id="section-7.1-2.3">
            <p id="section-7.1-2.3.1">The note for the iana-tunnel-type YANG
   module at <span>[<a href="#protocol-registries" class="xref">protocol-registries</a>]</span> has
   been updated to read:
   "This is one of the available formats of the Tunnel Types (tunnelType) registry."<a href="#section-7.1-2.3.1" class="pilcrow">¶</a></p>
</li>
          <li id="section-7.1-2.4">The new "Interface Parameters" category at <span>[<a href="#protocol-registries" class="xref">protocol-registries</a>]</span> includes entries for
   "Interface Types (ifType)" <span>[<a href="#ifType-registry" class="xref">ifType-registry</a>]</span>, "Tunnel Types (tunnelType)" <span>[<a href="#tunnelType-registry" class="xref">tunnelType-registry</a>]</span>, and "Transmission
   Number Values" <span>[<a href="#transmission-registry" class="xref">transmission-registry</a>]</span>.<a href="#section-7.1-2.4" class="pilcrow">¶</a>
</li>
          <li id="section-7.1-2.5">Update the "Interface Types (ifType)" registry <span>[<a href="#ifType-registry" class="xref">ifType-registry</a>]</span> to list MIB <span>[<a href="#IANAifType-MIB" class="xref">IANAifType-MIB</a>]</span> and YANG <span>[<a href="#yang-if-type" class="xref">yang-if-type</a>]</span> as Available Formats.<a href="#section-7.1-2.5" class="pilcrow">¶</a>
</li>
          <li id="section-7.1-2.6">Update the "Tunnel Types (tunnelType)" registry <span>[<a href="#tunnelType-registry" class="xref">tunnelType-registry</a>]</span> to list MIB <span>[<a href="#IANAifType-MIB" class="xref">IANAifType-MIB</a>]</span> and YANG <span>[<a href="#yang-tunnel-type" class="xref">yang-tunnel-type</a>]</span> as Available
   Formats.<a href="#section-7.1-2.6" class="pilcrow">¶</a>
</li>
          <li id="section-7.1-2.7">Replace the <span>[<a href="#yang-if-type" class="xref">yang-if-type</a>]</span> page
   with the YANG module content rather than having a page that claims
   to have multiple Available Formats.<a href="#section-7.1-2.7" class="pilcrow">¶</a>
</li>
          <li id="section-7.1-2.8">Replace the <span>[<a href="#yang-tunnel-type" class="xref">yang-tunnel-type</a>]</span>
   page with the YANG module content rather than having a page that
   claims to have multiple Available Formats.<a href="#section-7.1-2.8" class="pilcrow">¶</a>
</li>
          <li id="section-7.1-2.9">
            <p id="section-7.1-2.9.1">In addition, <span>[<a href="#IANAifType-MIB" class="xref">IANAifType-MIB</a>]</span> is to
 be updated as follows:<a href="#section-7.1-2.9.1" class="pilcrow">¶</a></p>
<p id="section-7.1-2.9.2">OLD:<a href="#section-7.1-2.9.2" class="pilcrow">¶</a></p>
<blockquote id="section-7.1-2.9.3"> 
Requests for new values should be made to IANA via email (iana@iana.org).<a href="#section-7.1-2.9.3" class="pilcrow">¶</a>
</blockquote>
<p id="section-7.1-2.9.4">NEW:<a href="#section-7.1-2.9.4" class="pilcrow">¶</a></p>
<blockquote id="section-7.1-2.9.5">
Interface types must not be directly added to the IANAifType-MIB MIB module.
They must instead be added to the "Interface Types (ifType)" registry at
<span>[<a href="#ifType-registry" class="xref">ifType-registry</a>]</span>.<a href="#section-7.1-2.9.5" class="pilcrow">¶</a>
</blockquote>
<p id="section-7.1-2.9.6">(Note that <span>[<a href="#yang-if-type" class="xref">yang-if-type</a>]</span> was
 previously updated with this language.)<a href="#section-7.1-2.9.6" class="pilcrow">¶</a></p>
</li>
          <li id="section-7.1-2.10">IANA has added this document as a reference in the "Interface Types
 (ifType)", "Tunnel Types (tunnelType)", and "Transmission Number
 Values" registries, as well as the iana-if-type
 YANG Module, iana-tunnel-type YANG Module, and IANAifType-MIB.<a href="#section-7.1-2.10" class="pilcrow">¶</a>
</li>
        </ol>
</section>
</div>
<div id="transmission-number-assignments">
<section id="section-7.2">
        <h3 id="name-transmission-number-assignm">
<a href="#section-7.2" class="section-number selfRef">7.2. </a><a href="#name-transmission-number-assignm" class="section-name selfRef">Transmission Number Assignments</a>
        </h3>
<p id="section-7.2-1">Per the discussion in <a href="#transmission-discussion" class="xref">Section 6.2</a>, <span>[<a href="#ifType-registry" class="xref">ifType-registry</a>]</span>
 has been updated as follows:<a href="#section-7.2-1" class="pilcrow">¶</a></p>
<p id="section-7.2-2">OLD:<a href="#section-7.2-2" class="pilcrow">¶</a></p>
<blockquote id="section-7.2-3">
For every ifType registration, the corresponding transmission 
number value should be registered or marked "Reserved".<a href="#section-7.2-3" class="pilcrow">¶</a>
</blockquote>
<p id="section-7.2-4">NEW:<a href="#section-7.2-4" class="pilcrow">¶</a></p>
<blockquote id="section-7.2-5">
For future ifType assignments, an OID-subtree assignment MIB-II's
'transmission' subtree will be made with the same value.<a href="#section-7.2-5" class="pilcrow">¶</a>
</blockquote>
<p id="section-7.2-6">Similarly, the following change has been made to <span>[<a href="#transmission-registry" class="xref">transmission-registry</a>]</span>:<a href="#section-7.2-6" class="pilcrow">¶</a></p>
<p id="section-7.2-7">OLD:<a href="#section-7.2-7" class="pilcrow">¶</a></p>
<blockquote id="section-7.2-8">
For every transmission number registration, the corresponding
ifType value should be registered or marked "Reserved".<a href="#section-7.2-8" class="pilcrow">¶</a>
</blockquote>
<p id="section-7.2-9">NEW:<a href="#section-7.2-9" class="pilcrow">¶</a></p>
<blockquote id="section-7.2-10">For future transmission number assignments, an 'ifType' will be made with the same value.<a href="#section-7.2-10" class="pilcrow">¶</a>
</blockquote>
</section>
</div>
</section>
</div>
<div id="security-considerations">
<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">Since this document does not introduce any technology or protocol,
there are no security issues to be considered for this document
itself.<a href="#section-8-1" class="pilcrow">¶</a></p>
<p id="section-8-2">For security considerations related to MIB and YANG modules that
expose these values, see <span><a href="https://www.rfc-editor.org/rfc/rfc2863#section-9" class="relref">Section 9</a> of [<a href="#RFC2863" class="xref">RFC2863</a>]</span>, <span><a href="https://www.rfc-editor.org/rfc/rfc4087#section-6" class="relref">Section 6</a> of [<a href="#RFC4087" class="xref">RFC4087</a>]</span>, 
and <span><a href="https://www.rfc-editor.org/rfc/rfc8675#section-3" class="relref">Section 3</a> of [<a href="#RFC8675" class="xref">RFC8675</a>]</span>.<a href="#section-8-2" class="pilcrow">¶</a></p>
</section>
</div>
<section id="section-9">
      <h2 id="name-references">
<a href="#section-9" class="section-number selfRef">9. </a><a href="#name-references" class="section-name selfRef">References</a>
      </h2>
<section id="section-9.1">
        <h3 id="name-normative-references">
<a href="#section-9.1" class="section-number selfRef">9.1. </a><a href="#name-normative-references" class="section-name selfRef">Normative References</a>
        </h3>
<dl class="references">
<dt id="RFC2119">[RFC2119]</dt>
        <dd>
<span class="refAuthor">Bradner, S.</span>, <span class="refTitle">"Key words for use in RFCs to Indicate Requirement Levels"</span>, <span class="seriesInfo">BCP 14</span>, <span class="seriesInfo">RFC 2119</span>, <span class="seriesInfo">DOI 10.17487/RFC2119</span>, <time datetime="1997-03" class="refDate">March 1997</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc2119">https://www.rfc-editor.org/info/rfc2119</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC2578">[RFC2578]</dt>
        <dd>
<span class="refAuthor">McCloghrie, K., Ed.</span><span class="refAuthor">, Perkins, D., Ed.</span><span class="refAuthor">, and J. Schoenwaelder, Ed.</span>, <span class="refTitle">"Structure of Management Information Version 2 (SMIv2)"</span>, <span class="seriesInfo">STD 58</span>, <span class="seriesInfo">RFC 2578</span>, <span class="seriesInfo">DOI 10.17487/RFC2578</span>, <time datetime="1999-04" class="refDate">April 1999</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc2578">https://www.rfc-editor.org/info/rfc2578</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC2863">[RFC2863]</dt>
        <dd>
<span class="refAuthor">McCloghrie, K.</span><span class="refAuthor"> and F. Kastenholz</span>, <span class="refTitle">"The Interfaces Group MIB"</span>, <span class="seriesInfo">RFC 2863</span>, <span class="seriesInfo">DOI 10.17487/RFC2863</span>, <time datetime="2000-06" class="refDate">June 2000</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc2863">https://www.rfc-editor.org/info/rfc2863</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC5378">[RFC5378]</dt>
        <dd>
<span class="refAuthor">Bradner, S., Ed.</span><span class="refAuthor"> and J. Contreras, Ed.</span>, <span class="refTitle">"Rights Contributors Provide to the IETF Trust"</span>, <span class="seriesInfo">BCP 78</span>, <span class="seriesInfo">RFC 5378</span>, <span class="seriesInfo">DOI 10.17487/RFC5378</span>, <time datetime="2008-11" class="refDate">November 2008</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc5378">https://www.rfc-editor.org/info/rfc5378</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8126">[RFC8126]</dt>
        <dd>
<span class="refAuthor">Cotton, M.</span><span class="refAuthor">, Leiba, B.</span><span class="refAuthor">, and T. Narten</span>, <span class="refTitle">"Guidelines for Writing an IANA Considerations Section in RFCs"</span>, <span class="seriesInfo">BCP 26</span>, <span class="seriesInfo">RFC 8126</span>, <span class="seriesInfo">DOI 10.17487/RFC8126</span>, <time datetime="2017-06" class="refDate">June 2017</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8126">https://www.rfc-editor.org/info/rfc8126</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8174">[RFC8174]</dt>
      <dd>
<span class="refAuthor">Leiba, B.</span>, <span class="refTitle">"Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words"</span>, <span class="seriesInfo">BCP 14</span>, <span class="seriesInfo">RFC 8174</span>, <span class="seriesInfo">DOI 10.17487/RFC8174</span>, <time datetime="2017-05" class="refDate">May 2017</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8174">https://www.rfc-editor.org/info/rfc8174</a>&gt;</span>. </dd>
<dd class="break"></dd>
</dl>
</section>
<section id="section-9.2">
        <h3 id="name-informative-references">
<a href="#section-9.2" class="section-number selfRef">9.2. </a><a href="#name-informative-references" class="section-name selfRef">Informative References</a>
        </h3>
<dl class="references">
<dt id="IANAifType-MIB">[IANAifType-MIB]</dt>
        <dd>
<span class="refAuthor">IANA</span>, <span class="refTitle">"IANAifType-MIB Definitions"</span>, <span>&lt;<a href="http://www.iana.org/assignments/ianaiftype-mib">http://www.iana.org/assignments/ianaiftype-mib</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="ifType-registry">[ifType-registry]</dt>
        <dd>
<span class="refAuthor">IANA</span>, <span class="refTitle">"Interface Types (ifType)"</span>, <span>&lt;<a href="https://www.iana.org/assignments/smi-numbers">https://www.iana.org/assignments/smi-numbers</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="protocol-registries">[protocol-registries]</dt>
        <dd>
<span class="refAuthor">IANA</span>, <span class="refTitle">"Protocol Registries"</span>, <span>&lt;<a href="https://www.iana.org/protocols">https://www.iana.org/protocols</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC1234">[RFC1234]</dt>
        <dd>
<span class="refAuthor">Provan, D.</span>, <span class="refTitle">"Tunneling IPX traffic through IP networks"</span>, <span class="seriesInfo">RFC 1234</span>, <span class="seriesInfo">DOI 10.17487/RFC1234</span>, <time datetime="1991-06" class="refDate">June 1991</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc1234">https://www.rfc-editor.org/info/rfc1234</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC1573">[RFC1573]</dt>
        <dd>
<span class="refAuthor">McCloghrie, K.</span><span class="refAuthor"> and F. Kastenholz</span>, <span class="refTitle">"Evolution of the Interfaces Group of MIB-II"</span>, <span class="seriesInfo">RFC 1573</span>, <span class="seriesInfo">DOI 10.17487/RFC1573</span>, <time datetime="1994-01" class="refDate">January 1994</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc1573">https://www.rfc-editor.org/info/rfc1573</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC2667">[RFC2667]</dt>
        <dd>
<span class="refAuthor">Thaler, D.</span>, <span class="refTitle">"IP Tunnel MIB"</span>, <span class="seriesInfo">RFC 2667</span>, <span class="seriesInfo">DOI 10.17487/RFC2667</span>, <time datetime="1999-08" class="refDate">August 1999</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc2667">https://www.rfc-editor.org/info/rfc2667</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC3635">[RFC3635]</dt>
        <dd>
<span class="refAuthor">Flick, J.</span>, <span class="refTitle">"Definitions of Managed Objects for the Ethernet-like Interface Types"</span>, <span class="seriesInfo">RFC 3635</span>, <span class="seriesInfo">DOI 10.17487/RFC3635</span>, <time datetime="2003-09" class="refDate">September 2003</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc3635">https://www.rfc-editor.org/info/rfc3635</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC3637">[RFC3637]</dt>
        <dd>
<span class="refAuthor">Heard, C.M., Ed.</span>, <span class="refTitle">"Definitions of Managed Objects for the Ethernet WAN Interface Sublayer"</span>, <span class="seriesInfo">RFC 3637</span>, <span class="seriesInfo">DOI 10.17487/RFC3637</span>, <time datetime="2003-09" class="refDate">September 2003</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc3637">https://www.rfc-editor.org/info/rfc3637</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC4087">[RFC4087]</dt>
        <dd>
<span class="refAuthor">Thaler, D.</span>, <span class="refTitle">"IP Tunnel MIB"</span>, <span class="seriesInfo">RFC 4087</span>, <span class="seriesInfo">DOI 10.17487/RFC4087</span>, <time datetime="2005-06" class="refDate">June 2005</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc4087">https://www.rfc-editor.org/info/rfc4087</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC4380">[RFC4380]</dt>
        <dd>
<span class="refAuthor">Huitema, C.</span>, <span class="refTitle">"Teredo: Tunneling IPv6 over UDP through Network Address Translations (NATs)"</span>, <span class="seriesInfo">RFC 4380</span>, <span class="seriesInfo">DOI 10.17487/RFC4380</span>, <time datetime="2006-02" class="refDate">February 2006</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc4380">https://www.rfc-editor.org/info/rfc4380</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC5066">[RFC5066]</dt>
        <dd>
<span class="refAuthor">Beili, E.</span>, <span class="refTitle">"Ethernet in the First Mile Copper (EFMCu) Interfaces MIB"</span>, <span class="seriesInfo">RFC 5066</span>, <span class="seriesInfo">DOI 10.17487/RFC5066</span>, <time datetime="2007-11" class="refDate">November 2007</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc5066">https://www.rfc-editor.org/info/rfc5066</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC7224">[RFC7224]</dt>
        <dd>
<span class="refAuthor">Bjorklund, M.</span>, <span class="refTitle">"IANA Interface Type YANG Module"</span>, <span class="seriesInfo">RFC 7224</span>, <span class="seriesInfo">DOI 10.17487/RFC7224</span>, <time datetime="2014-05" class="refDate">May 2014</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc7224">https://www.rfc-editor.org/info/rfc7224</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="RFC8675">[RFC8675]</dt>
        <dd>
<span class="refAuthor">Boucadair, M.</span><span class="refAuthor">, Farrer, I.</span><span class="refAuthor">, and R. Asati</span>, <span class="refTitle">"A YANG Data Model for Tunnel Interface Types"</span>, <span class="seriesInfo">RFC 8675</span>, <span class="seriesInfo">DOI 10.17487/RFC8675</span>, <time datetime="2019-11" class="refDate">November 2019</time>, <span>&lt;<a href="https://www.rfc-editor.org/info/rfc8675">https://www.rfc-editor.org/info/rfc8675</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="transmission-registry">[transmission-registry]</dt>
        <dd>
<span class="refAuthor">IANA</span>, <span class="refTitle">"Transmission Number Values"</span>, <span>&lt;<a href="https://www.iana.org/assignments/smi-numbers">https://www.iana.org/assignments/smi-numbers</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="tunnelType-registry">[tunnelType-registry]</dt>
        <dd>
<span class="refAuthor">IANA</span>, <span class="refTitle">"Tunnel Types (tunnelType)"</span>, <span>&lt;<a href="https://www.iana.org/assignments/smi-numbers">https://www.iana.org/assignments/smi-numbers</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="yang-if-type">[yang-if-type]</dt>
        <dd>
<span class="refAuthor">IANA</span>, <span class="refTitle">"iana-if-type YANG Module"</span>, <span>&lt;<a href="http://www.iana.org/assignments/iana-if-type">http://www.iana.org/assignments/iana-if-type</a>&gt;</span>. </dd>
<dd class="break"></dd>
<dt id="yang-tunnel-type">[yang-tunnel-type]</dt>
      <dd>
<span class="refAuthor">IANA</span>, <span class="refTitle">"iana-tunnel-type YANG Module"</span>, <span>&lt;<a href="https://www.iana.org/assignments/iana-tunnel-type">https://www.iana.org/assignments/iana-tunnel-type</a>&gt;</span>. </dd>
<dd class="break"></dd>
</dl>
</section>
</section>
<div id="authors-addresses">
<section id="section-appendix.a">
      <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">Dave Thaler</span></div>
<div dir="auto" class="left"><span class="org">Microsoft</span></div>
<div class="email">
<span>Email:</span>
<a href="mailto:dthaler@microsoft.com" class="email">dthaler@microsoft.com</a>
</div>
</address>
<address class="vcard">
        <div dir="auto" class="left"><span class="fn nameRole">Dan Romascanu</span></div>
<div dir="auto" class="left"><span class="org">Independent</span></div>
<div class="email">
<span>Email:</span>
<a href="mailto:dromasca@gmail.com" class="email">dromasca@gmail.com</a>
</div>
</address>
</section>
</div>
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