CINXE.COM

<!DOCTYPE html> <html class="client-nojs vector-feature-language-in-header-enabled vector-feature-language-in-main-page-header-disabled vector-feature-sticky-header-disabled vector-feature-page-tools-pinned-disabled vector-feature-toc-pinned-clientpref-1 vector-feature-main-menu-pinned-disabled vector-feature-limited-width-clientpref-1 vector-feature-limited-width-content-enabled vector-feature-custom-font-size-clientpref-1 vector-feature-appearance-pinned-clientpref-1 vector-feature-night-mode-enabled skin-theme-clientpref-day vector-toc-available" lang="en" dir="ltr"> <head> <meta charset="UTF-8"> <title>Precision Time Protocol - Wikipedia</title> <script>(function(){var className="client-js vector-feature-language-in-header-enabled vector-feature-language-in-main-page-header-disabled vector-feature-sticky-header-disabled vector-feature-page-tools-pinned-disabled vector-feature-toc-pinned-clientpref-1 vector-feature-main-menu-pinned-disabled vector-feature-limited-width-clientpref-1 vector-feature-limited-width-content-enabled vector-feature-custom-font-size-clientpref-1 vector-feature-appearance-pinned-clientpref-1 vector-feature-night-mode-enabled skin-theme-clientpref-day vector-toc-available";var cookie=document.cookie.match(/(?:^|; )enwikimwclientpreferences=([^;]+)/);if(cookie){cookie[1].split('%2C').forEach(function(pref){className=className.replace(new RegExp('(^| )'+pref.replace(/-clientpref-\w+$|[^\w-]+/g,'')+'-clientpref-\\w+( |$)'),'$1'+pref+'$2');});}document.documentElement.className=className;}());RLCONF={"wgBreakFrames":false,"wgSeparatorTransformTable":["",""],"wgDigitTransformTable":["",""],"wgDefaultDateFormat":"dmy", "wgMonthNames":["","January","February","March","April","May","June","July","August","September","October","November","December"],"wgRequestId":"3ad410ee-87e9-443f-87cf-309e49841294","wgCanonicalNamespace":"","wgCanonicalSpecialPageName":false,"wgNamespaceNumber":0,"wgPageName":"Precision_Time_Protocol","wgTitle":"Precision Time Protocol","wgCurRevisionId":1247519903,"wgRevisionId":1247519903,"wgArticleId":2142269,"wgIsArticle":true,"wgIsRedirect":false,"wgAction":"view","wgUserName":null,"wgUserGroups":["*"],"wgCategories":["All articles with dead external links","Articles with dead external links from February 2022","Articles with short description","Short description matches Wikidata","Use American English from April 2020","All Wikipedia articles written in American English","Use dmy dates from June 2020","All articles with unsourced statements","Articles with unsourced statements from September 2024","Synchronization","IEEE standards","Network time-related software", "Network protocols","Application layer protocols"],"wgPageViewLanguage":"en","wgPageContentLanguage":"en","wgPageContentModel":"wikitext","wgRelevantPageName":"Precision_Time_Protocol","wgRelevantArticleId":2142269,"wgIsProbablyEditable":true,"wgRelevantPageIsProbablyEditable":true,"wgRestrictionEdit":[],"wgRestrictionMove":[],"wgRedirectedFrom":"IEEE_802.1AS","wgNoticeProject":"wikipedia","wgCiteReferencePreviewsActive":false,"wgFlaggedRevsParams":{"tags":{"status":{"levels":1}}},"wgMediaViewerOnClick":true,"wgMediaViewerEnabledByDefault":true,"wgPopupsFlags":0,"wgVisualEditor":{"pageLanguageCode":"en","pageLanguageDir":"ltr","pageVariantFallbacks":"en"},"wgMFDisplayWikibaseDescriptions":{"search":true,"watchlist":true,"tagline":false,"nearby":true},"wgWMESchemaEditAttemptStepOversample":false,"wgWMEPageLength":30000,"wgInternalRedirectTargetUrl":"/wiki/Precision_Time_Protocol","wgRelatedArticlesCompat":[],"wgCentralAuthMobileDomain":false,"wgEditSubmitButtonLabelPublish":true, "wgULSPosition":"interlanguage","wgULSisCompactLinksEnabled":false,"wgVector2022LanguageInHeader":true,"wgULSisLanguageSelectorEmpty":false,"wgWikibaseItemId":"Q1143243","wgCheckUserClientHintsHeadersJsApi":["brands","architecture","bitness","fullVersionList","mobile","model","platform","platformVersion"],"GEHomepageSuggestedEditsEnableTopics":true,"wgGETopicsMatchModeEnabled":false,"wgGEStructuredTaskRejectionReasonTextInputEnabled":false,"wgGELevelingUpEnabledForUser":false};RLSTATE={"ext.globalCssJs.user.styles":"ready","site.styles":"ready","user.styles":"ready","ext.globalCssJs.user":"ready","user":"ready","user.options":"loading","ext.cite.styles":"ready","ext.math.styles":"ready","skins.vector.search.codex.styles":"ready","skins.vector.styles":"ready","skins.vector.icons":"ready","jquery.makeCollapsible.styles":"ready","ext.wikimediamessages.styles":"ready","ext.visualEditor.desktopArticleTarget.noscript":"ready","ext.uls.interlanguage":"ready","wikibase.client.init":"ready", "ext.wikimediaBadges":"ready"};RLPAGEMODULES=["mediawiki.action.view.redirect","ext.cite.ux-enhancements","mediawiki.page.media","site","mediawiki.page.ready","jquery.makeCollapsible","mediawiki.toc","skins.vector.js","ext.centralNotice.geoIP","ext.centralNotice.startUp","ext.gadget.ReferenceTooltips","ext.gadget.switcher","ext.urlShortener.toolbar","ext.centralauth.centralautologin","mmv.bootstrap","ext.popups","ext.visualEditor.desktopArticleTarget.init","ext.visualEditor.targetLoader","ext.echo.centralauth","ext.eventLogging","ext.wikimediaEvents","ext.navigationTiming","ext.uls.interface","ext.cx.eventlogging.campaigns","ext.cx.uls.quick.actions","wikibase.client.vector-2022","ext.checkUser.clientHints","ext.quicksurveys.init","ext.growthExperiments.SuggestedEditSession","wikibase.sidebar.tracking"];</script> <script>(RLQ=window.RLQ||[]).push(function(){mw.loader.impl(function(){return["user.options@12s5i",function($,jQuery,require,module){mw.user.tokens.set({"patrolToken":"+\\","watchToken":"+\\","csrfToken":"+\\"}); }];});});</script> <link rel="stylesheet" href="/w/load.php?lang=en&modules=ext.cite.styles%7Cext.math.styles%7Cext.uls.interlanguage%7Cext.visualEditor.desktopArticleTarget.noscript%7Cext.wikimediaBadges%7Cext.wikimediamessages.styles%7Cjquery.makeCollapsible.styles%7Cskins.vector.icons%2Cstyles%7Cskins.vector.search.codex.styles%7Cwikibase.client.init&only=styles&skin=vector-2022"> <script async="" src="/w/load.php?lang=en&modules=startup&only=scripts&raw=1&skin=vector-2022"></script> <meta name="ResourceLoaderDynamicStyles" content=""> <link rel="stylesheet" href="/w/load.php?lang=en&modules=site.styles&only=styles&skin=vector-2022"> <meta name="generator" content="MediaWiki 1.44.0-wmf.4"> <meta name="referrer" content="origin"> <meta name="referrer" content="origin-when-cross-origin"> <meta name="robots" content="max-image-preview:standard"> <meta name="format-detection" content="telephone=no"> <meta name="viewport" content="width=1120"> <meta property="og:title" content="Precision Time Protocol - Wikipedia"> <meta property="og:type" content="website"> <link rel="preconnect" href="//upload.wikimedia.org"> <link rel="alternate" media="only screen and (max-width: 640px)" href="//en.m.wikipedia.org/wiki/Precision_Time_Protocol"> <link rel="alternate" type="application/x-wiki" title="Edit this page" href="/w/index.php?title=Precision_Time_Protocol&action=edit"> <link rel="apple-touch-icon" href="/static/apple-touch/wikipedia.png"> <link rel="icon" href="/static/favicon/wikipedia.ico"> <link rel="search" type="application/opensearchdescription+xml" href="/w/rest.php/v1/search" title="Wikipedia (en)"> <link rel="EditURI" type="application/rsd+xml" href="//en.wikipedia.org/w/api.php?action=rsd"> <link rel="canonical" href="https://en.wikipedia.org/wiki/Precision_Time_Protocol"> <link rel="license" href="https://creativecommons.org/licenses/by-sa/4.0/deed.en"> <link rel="alternate" type="application/atom+xml" title="Wikipedia Atom feed" href="/w/index.php?title=Special:RecentChanges&feed=atom"> <link rel="dns-prefetch" href="//meta.wikimedia.org" /> <link rel="dns-prefetch" href="//login.wikimedia.org"> </head> <body class="skin--responsive skin-vector skin-vector-search-vue mediawiki ltr sitedir-ltr mw-hide-empty-elt ns-0 ns-subject mw-editable page-Precision_Time_Protocol rootpage-Precision_Time_Protocol skin-vector-2022 action-view"><a class="mw-jump-link" href="#bodyContent">Jump to content</a> <div class="vector-header-container"> <header class="vector-header mw-header"> <div class="vector-header-start"> <nav class="vector-main-menu-landmark" aria-label="Site"> <div id="vector-main-menu-dropdown" class="vector-dropdown vector-main-menu-dropdown vector-button-flush-left vector-button-flush-right" > <input type="checkbox" id="vector-main-menu-dropdown-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-main-menu-dropdown" class="vector-dropdown-checkbox " aria-label="Main menu" > <label id="vector-main-menu-dropdown-label" for="vector-main-menu-dropdown-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" ><span class="vector-icon mw-ui-icon-menu mw-ui-icon-wikimedia-menu"></span> <span class="vector-dropdown-label-text">Main menu</span> </label> <div class="vector-dropdown-content"> <div id="vector-main-menu-unpinned-container" class="vector-unpinned-container"> <div id="vector-main-menu" class="vector-main-menu vector-pinnable-element"> <div class="vector-pinnable-header vector-main-menu-pinnable-header vector-pinnable-header-unpinned" data-feature-name="main-menu-pinned" data-pinnable-element-id="vector-main-menu" data-pinned-container-id="vector-main-menu-pinned-container" data-unpinned-container-id="vector-main-menu-unpinned-container" > <div class="vector-pinnable-header-label">Main menu</div> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-pin-button" data-event-name="pinnable-header.vector-main-menu.pin">move to sidebar</button> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-unpin-button" data-event-name="pinnable-header.vector-main-menu.unpin">hide</button> </div> <div id="p-navigation" class="vector-menu mw-portlet mw-portlet-navigation" > <div class="vector-menu-heading"> Navigation </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="n-mainpage-description" class="mw-list-item"><a href="/wiki/Main_Page" title="Visit the main page [z]" accesskey="z"><span>Main page</span></a></li><li id="n-contents" class="mw-list-item"><a href="/wiki/Wikipedia:Contents" title="Guides to browsing Wikipedia"><span>Contents</span></a></li><li id="n-currentevents" class="mw-list-item"><a href="/wiki/Portal:Current_events" title="Articles related to current events"><span>Current events</span></a></li><li id="n-randompage" class="mw-list-item"><a href="/wiki/Special:Random" title="Visit a randomly selected article [x]" accesskey="x"><span>Random article</span></a></li><li id="n-aboutsite" class="mw-list-item"><a href="/wiki/Wikipedia:About" title="Learn about Wikipedia and how it works"><span>About Wikipedia</span></a></li><li id="n-contactpage" class="mw-list-item"><a href="//en.wikipedia.org/wiki/Wikipedia:Contact_us" title="How to contact Wikipedia"><span>Contact us</span></a></li> </ul> </div> </div> <div id="p-interaction" class="vector-menu mw-portlet mw-portlet-interaction" > <div class="vector-menu-heading"> Contribute </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="n-help" class="mw-list-item"><a href="/wiki/Help:Contents" title="Guidance on how to use and edit Wikipedia"><span>Help</span></a></li><li id="n-introduction" class="mw-list-item"><a href="/wiki/Help:Introduction" title="Learn how to edit Wikipedia"><span>Learn to edit</span></a></li><li id="n-portal" class="mw-list-item"><a href="/wiki/Wikipedia:Community_portal" title="The hub for editors"><span>Community portal</span></a></li><li id="n-recentchanges" class="mw-list-item"><a href="/wiki/Special:RecentChanges" title="A list of recent changes to Wikipedia [r]" accesskey="r"><span>Recent changes</span></a></li><li id="n-upload" class="mw-list-item"><a href="/wiki/Wikipedia:File_upload_wizard" title="Add images or other media for use on Wikipedia"><span>Upload file</span></a></li> </ul> </div> </div> </div> </div> </div> </div> </nav> <a href="/wiki/Main_Page" class="mw-logo"> <img class="mw-logo-icon" src="/static/images/icons/wikipedia.png" alt="" aria-hidden="true" height="50" width="50"> <span class="mw-logo-container skin-invert"> <img class="mw-logo-wordmark" alt="Wikipedia" src="/static/images/mobile/copyright/wikipedia-wordmark-en.svg" style="width: 7.5em; height: 1.125em;"> <img class="mw-logo-tagline" alt="The Free Encyclopedia" src="/static/images/mobile/copyright/wikipedia-tagline-en.svg" width="117" height="13" style="width: 7.3125em; height: 0.8125em;"> </span> </a> </div> <div class="vector-header-end"> <div id="p-search" role="search" class="vector-search-box-vue vector-search-box-collapses vector-search-box-show-thumbnail vector-search-box-auto-expand-width vector-search-box"> <a href="/wiki/Special:Search" class="cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only search-toggle" title="Search Wikipedia [f]" accesskey="f"><span class="vector-icon mw-ui-icon-search mw-ui-icon-wikimedia-search"></span> <span>Search</span> </a> <div class="vector-typeahead-search-container"> <div class="cdx-typeahead-search cdx-typeahead-search--show-thumbnail cdx-typeahead-search--auto-expand-width"> <form action="/w/index.php" id="searchform" class="cdx-search-input cdx-search-input--has-end-button"> <div id="simpleSearch" class="cdx-search-input__input-wrapper" data-search-loc="header-moved"> <div class="cdx-text-input cdx-text-input--has-start-icon"> <input class="cdx-text-input__input" type="search" name="search" placeholder="Search Wikipedia" aria-label="Search Wikipedia" autocapitalize="sentences" title="Search Wikipedia [f]" accesskey="f" id="searchInput" > <span class="cdx-text-input__icon cdx-text-input__start-icon"></span> </div> <input type="hidden" name="title" value="Special:Search"> </div> <button class="cdx-button cdx-search-input__end-button">Search</button> </form> </div> </div> </div> <nav class="vector-user-links vector-user-links-wide" aria-label="Personal tools"> <div class="vector-user-links-main"> <div id="p-vector-user-menu-preferences" class="vector-menu mw-portlet emptyPortlet" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> </ul> </div> </div> <div id="p-vector-user-menu-userpage" class="vector-menu mw-portlet emptyPortlet" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> </ul> </div> </div> <nav class="vector-appearance-landmark" aria-label="Appearance"> <div id="vector-appearance-dropdown" class="vector-dropdown " title="Change the appearance of the page's font size, width, and color" > <input type="checkbox" id="vector-appearance-dropdown-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-appearance-dropdown" class="vector-dropdown-checkbox " aria-label="Appearance" > <label id="vector-appearance-dropdown-label" for="vector-appearance-dropdown-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" ><span class="vector-icon mw-ui-icon-appearance mw-ui-icon-wikimedia-appearance"></span> <span class="vector-dropdown-label-text">Appearance</span> </label> <div class="vector-dropdown-content"> <div id="vector-appearance-unpinned-container" class="vector-unpinned-container"> </div> </div> </div> </nav> <div id="p-vector-user-menu-notifications" class="vector-menu mw-portlet emptyPortlet" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> </ul> </div> </div> <div id="p-vector-user-menu-overflow" class="vector-menu mw-portlet" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="pt-sitesupport-2" class="user-links-collapsible-item mw-list-item user-links-collapsible-item"><a data-mw="interface" href="https://donate.wikimedia.org/wiki/Special:FundraiserRedirector?utm_source=donate&utm_medium=sidebar&utm_campaign=C13_en.wikipedia.org&uselang=en" class=""><span>Donate</span></a> </li> <li id="pt-createaccount-2" class="user-links-collapsible-item mw-list-item user-links-collapsible-item"><a data-mw="interface" href="/w/index.php?title=Special:CreateAccount&returnto=Precision+Time+Protocol" title="You are encouraged to create an account and log in; however, it is not mandatory" class=""><span>Create account</span></a> </li> <li id="pt-login-2" class="user-links-collapsible-item mw-list-item user-links-collapsible-item"><a data-mw="interface" href="/w/index.php?title=Special:UserLogin&returnto=Precision+Time+Protocol" title="You're encouraged to log in; however, it's not mandatory. [o]" accesskey="o" class=""><span>Log in</span></a> </li> </ul> </div> </div> </div> <div id="vector-user-links-dropdown" class="vector-dropdown vector-user-menu vector-button-flush-right vector-user-menu-logged-out" title="Log in and more options" > <input type="checkbox" id="vector-user-links-dropdown-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-user-links-dropdown" class="vector-dropdown-checkbox " aria-label="Personal tools" > <label id="vector-user-links-dropdown-label" for="vector-user-links-dropdown-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" ><span class="vector-icon mw-ui-icon-ellipsis mw-ui-icon-wikimedia-ellipsis"></span> <span class="vector-dropdown-label-text">Personal tools</span> </label> <div class="vector-dropdown-content"> <div id="p-personal" class="vector-menu mw-portlet mw-portlet-personal user-links-collapsible-item" title="User menu" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="pt-sitesupport" class="user-links-collapsible-item mw-list-item"><a href="https://donate.wikimedia.org/wiki/Special:FundraiserRedirector?utm_source=donate&utm_medium=sidebar&utm_campaign=C13_en.wikipedia.org&uselang=en"><span>Donate</span></a></li><li id="pt-createaccount" class="user-links-collapsible-item mw-list-item"><a href="/w/index.php?title=Special:CreateAccount&returnto=Precision+Time+Protocol" title="You are encouraged to create an account and log in; however, it is not mandatory"><span class="vector-icon mw-ui-icon-userAdd mw-ui-icon-wikimedia-userAdd"></span> <span>Create account</span></a></li><li id="pt-login" class="user-links-collapsible-item mw-list-item"><a href="/w/index.php?title=Special:UserLogin&returnto=Precision+Time+Protocol" title="You're encouraged to log in; however, it's not mandatory. [o]" accesskey="o"><span class="vector-icon mw-ui-icon-logIn mw-ui-icon-wikimedia-logIn"></span> <span>Log in</span></a></li> </ul> </div> </div> <div id="p-user-menu-anon-editor" class="vector-menu mw-portlet mw-portlet-user-menu-anon-editor" > <div class="vector-menu-heading"> Pages for logged out editors <a href="/wiki/Help:Introduction" aria-label="Learn more about editing"><span>learn more</span></a> </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="pt-anoncontribs" class="mw-list-item"><a href="/wiki/Special:MyContributions" title="A list of edits made from this IP address [y]" accesskey="y"><span>Contributions</span></a></li><li id="pt-anontalk" class="mw-list-item"><a href="/wiki/Special:MyTalk" title="Discussion about edits from this IP address [n]" accesskey="n"><span>Talk</span></a></li> </ul> </div> </div> </div> </div> </nav> </div> </header> </div> <div class="mw-page-container"> <div class="mw-page-container-inner"> <div class="vector-sitenotice-container"> <div id="siteNotice"></div> </div> <div class="vector-column-start"> <div class="vector-main-menu-container"> <div id="mw-navigation"> <nav id="mw-panel" class="vector-main-menu-landmark" aria-label="Site"> <div id="vector-main-menu-pinned-container" class="vector-pinned-container"> </div> </nav> </div> </div> <div class="vector-sticky-pinned-container"> <nav id="mw-panel-toc" aria-label="Contents" data-event-name="ui.sidebar-toc" class="mw-table-of-contents-container vector-toc-landmark"> <div id="vector-toc-pinned-container" class="vector-pinned-container"> <div id="vector-toc" class="vector-toc vector-pinnable-element"> <div class="vector-pinnable-header vector-toc-pinnable-header vector-pinnable-header-pinned" data-feature-name="toc-pinned" data-pinnable-element-id="vector-toc" > <h2 class="vector-pinnable-header-label">Contents</h2> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-pin-button" data-event-name="pinnable-header.vector-toc.pin">move to sidebar</button> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-unpin-button" data-event-name="pinnable-header.vector-toc.unpin">hide</button> </div> <ul class="vector-toc-contents" id="mw-panel-toc-list"> <li id="toc-mw-content-text" class="vector-toc-list-item vector-toc-level-1"> <a href="#" class="vector-toc-link"> <div class="vector-toc-text">(Top)</div> </a> </li> <li id="toc-History" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#History"> <div class="vector-toc-text"> <span class="vector-toc-numb">1</span> <span>History</span> </div> </a> <ul id="toc-History-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Architecture" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Architecture"> <div class="vector-toc-text"> <span class="vector-toc-numb">2</span> <span>Architecture</span> </div> </a> <ul id="toc-Architecture-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Protocol_details" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Protocol_details"> <div class="vector-toc-text"> <span class="vector-toc-numb">3</span> <span>Protocol details</span> </div> </a> <button aria-controls="toc-Protocol_details-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Protocol details subsection</span> </button> <ul id="toc-Protocol_details-sublist" class="vector-toc-list"> <li id="toc-Message_transport" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Message_transport"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.1</span> <span>Message transport</span> </div> </a> <ul id="toc-Message_transport-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Domains" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Domains"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.2</span> <span>Domains</span> </div> </a> <ul id="toc-Domains-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Best_master_clock_algorithm" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Best_master_clock_algorithm"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>Best master clock algorithm</span> </div> </a> <ul id="toc-Best_master_clock_algorithm-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Synchronization" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Synchronization"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>Synchronization</span> </div> </a> <ul id="toc-Synchronization-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Optional_features" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Optional_features"> <div class="vector-toc-text"> <span class="vector-toc-numb">6</span> <span>Optional features</span> </div> </a> <ul id="toc-Optional_features-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Related_initiatives" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Related_initiatives"> <div class="vector-toc-text"> <span class="vector-toc-numb">7</span> <span>Related initiatives</span> </div> </a> <ul id="toc-Related_initiatives-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-See_also" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#See_also"> <div class="vector-toc-text"> <span class="vector-toc-numb">8</span> <span>See also</span> </div> </a> <ul id="toc-See_also-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Notes" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Notes"> <div class="vector-toc-text"> <span class="vector-toc-numb">9</span> <span>Notes</span> </div> </a> <ul id="toc-Notes-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-References" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#References"> <div class="vector-toc-text"> <span class="vector-toc-numb">10</span> <span>References</span> </div> </a> <ul id="toc-References-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-External_links" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#External_links"> <div class="vector-toc-text"> <span class="vector-toc-numb">11</span> <span>External links</span> </div> </a> <ul id="toc-External_links-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> </nav> </div> </div> <div class="mw-content-container"> <main id="content" class="mw-body"> <header class="mw-body-header vector-page-titlebar"> <nav aria-label="Contents" class="vector-toc-landmark"> <div id="vector-page-titlebar-toc" class="vector-dropdown vector-page-titlebar-toc vector-button-flush-left" > <input type="checkbox" id="vector-page-titlebar-toc-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-titlebar-toc" class="vector-dropdown-checkbox " aria-label="Toggle the table of contents" > <label id="vector-page-titlebar-toc-label" for="vector-page-titlebar-toc-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" ><span class="vector-icon mw-ui-icon-listBullet mw-ui-icon-wikimedia-listBullet"></span> <span class="vector-dropdown-label-text">Toggle the table of contents</span> </label> <div class="vector-dropdown-content"> <div id="vector-page-titlebar-toc-unpinned-container" class="vector-unpinned-container"> </div> </div> </div> </nav> <h1 id="firstHeading" class="firstHeading mw-first-heading"><span class="mw-page-title-main">Precision Time Protocol</span></h1> <div id="p-lang-btn" class="vector-dropdown mw-portlet mw-portlet-lang" > <input type="checkbox" id="p-lang-btn-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-p-lang-btn" class="vector-dropdown-checkbox mw-interlanguage-selector" aria-label="Go to an article in another language. Available in 16 languages" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-16" aria-hidden="true" ><span class="vector-icon mw-ui-icon-language-progressive mw-ui-icon-wikimedia-language-progressive"></span> <span class="vector-dropdown-label-text">16 languages</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-ca mw-list-item"><a href="https://ca.wikipedia.org/wiki/Precision_Time_Protocol" title="Precision Time Protocol – Catalan" lang="ca" hreflang="ca" data-title="Precision Time Protocol" data-language-autonym="Català" data-language-local-name="Catalan" class="interlanguage-link-target"><span>Català</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/Precision_Time_Protocol" title="Precision Time Protocol – German" lang="de" hreflang="de" data-title="Precision Time Protocol" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/Protocolo_de_tiempo_de_precisi%C3%B3n" title="Protocolo de tiempo de precisión – Spanish" lang="es" hreflang="es" data-title="Protocolo de tiempo de precisión" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Precision_Time_Protocol" title="Precision Time Protocol – French" lang="fr" hreflang="fr" data-title="Precision Time Protocol" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/%EC%A0%95%EB%B0%80_%EC%8B%9C%EA%B0%81_%ED%94%84%EB%A1%9C%ED%86%A0%EC%BD%9C" title="정밀 시각 프로토콜 – Korean" lang="ko" hreflang="ko" data-title="정밀 시각 프로토콜" data-language-autonym="한국어" data-language-local-name="Korean" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-id mw-list-item"><a href="https://id.wikipedia.org/wiki/Protokol_Waktu_Presisi_(Precision_Time_Protocol_-_PTP)" title="Protokol Waktu Presisi (Precision Time Protocol - PTP) – Indonesian" lang="id" hreflang="id" data-title="Protokol Waktu Presisi (Precision Time Protocol - PTP)" data-language-autonym="Bahasa Indonesia" data-language-local-name="Indonesian" class="interlanguage-link-target"><span>Bahasa Indonesia</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/Precision_Time_Protocol" title="Precision Time Protocol – Italian" lang="it" hreflang="it" data-title="Precision Time Protocol" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-he mw-list-item"><a href="https://he.wikipedia.org/wiki/Precision_Time_Protocol" title="Precision Time Protocol – Hebrew" lang="he" hreflang="he" data-title="Precision Time Protocol" data-language-autonym="עברית" data-language-local-name="Hebrew" class="interlanguage-link-target"><span>עברית</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/Precision_Time_Protocol" title="Precision Time Protocol – Japanese" lang="ja" hreflang="ja" data-title="Precision Time Protocol" data-language-autonym="日本語" data-language-local-name="Japanese" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/Precision_Time_Protocol" title="Precision Time Protocol – Polish" lang="pl" hreflang="pl" data-title="Precision Time Protocol" data-language-autonym="Polski" data-language-local-name="Polish" class="interlanguage-link-target"><span>Polski</span></a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/Precision_Time_Protocol" title="Precision Time Protocol – Portuguese" lang="pt" hreflang="pt" data-title="Precision Time Protocol" data-language-autonym="Português" data-language-local-name="Portuguese" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/%D0%9F%D1%80%D0%BE%D1%82%D0%BE%D0%BA%D0%BE%D0%BB_%D1%82%D0%BE%D1%87%D0%BD%D0%BE%D0%B3%D0%BE_%D0%B2%D1%80%D0%B5%D0%BC%D0%B5%D0%BD%D0%B8" title="Протокол точного времени – Russian" lang="ru" hreflang="ru" data-title="Протокол точного времени" data-language-autonym="Русский" data-language-local-name="Russian" class="interlanguage-link-target"><span>Русский</span></a></li><li class="interlanguage-link interwiki-fi mw-list-item"><a href="https://fi.wikipedia.org/wiki/Precision_Time_Protocol" title="Precision Time Protocol – Finnish" lang="fi" hreflang="fi" data-title="Precision Time Protocol" data-language-autonym="Suomi" data-language-local-name="Finnish" class="interlanguage-link-target"><span>Suomi</span></a></li><li class="interlanguage-link interwiki-sv mw-list-item"><a href="https://sv.wikipedia.org/wiki/Precision_Time_Protocol" title="Precision Time Protocol – Swedish" lang="sv" hreflang="sv" data-title="Precision Time Protocol" data-language-autonym="Svenska" data-language-local-name="Swedish" class="interlanguage-link-target"><span>Svenska</span></a></li><li class="interlanguage-link interwiki-tr mw-list-item"><a href="https://tr.wikipedia.org/wiki/Hassas_Zaman_Protokol%C3%BC" title="Hassas Zaman Protokolü – Turkish" lang="tr" hreflang="tr" data-title="Hassas Zaman Protokolü" data-language-autonym="Türkçe" data-language-local-name="Turkish" class="interlanguage-link-target"><span>Türkçe</span></a></li><li class="interlanguage-link interwiki-zh mw-list-item"><a href="https://zh.wikipedia.org/wiki/%E7%B2%BE%E7%A2%BA%E6%99%82%E9%96%93%E5%8D%94%E8%AD%B0" title="精確時間協議 – Chinese" lang="zh" hreflang="zh" data-title="精確時間協議" data-language-autonym="中文" data-language-local-name="Chinese" class="interlanguage-link-target"><span>中文</span></a></li> </ul> <div class="after-portlet after-portlet-lang"><span class="wb-langlinks-edit wb-langlinks-link"><a href="https://www.wikidata.org/wiki/Special:EntityPage/Q1143243#sitelinks-wikipedia" title="Edit interlanguage links" class="wbc-editpage">Edit links</a></span></div> </div> </div> </div> </header> <div class="vector-page-toolbar"> <div class="vector-page-toolbar-container"> <div id="left-navigation"> <nav aria-label="Namespaces"> <div id="p-associated-pages" class="vector-menu vector-menu-tabs mw-portlet mw-portlet-associated-pages" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="ca-nstab-main" class="selected vector-tab-noicon mw-list-item"><a href="/wiki/Precision_Time_Protocol" title="View the content page [c]" accesskey="c"><span>Article</span></a></li><li id="ca-talk" class="vector-tab-noicon mw-list-item"><a href="/wiki/Talk:Precision_Time_Protocol" rel="discussion" title="Discuss improvements to the content page [t]" accesskey="t"><span>Talk</span></a></li> </ul> </div> </div> <div id="vector-variants-dropdown" class="vector-dropdown emptyPortlet" > <input type="checkbox" id="vector-variants-dropdown-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-variants-dropdown" class="vector-dropdown-checkbox " aria-label="Change language variant" > <label id="vector-variants-dropdown-label" for="vector-variants-dropdown-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet" aria-hidden="true" ><span class="vector-dropdown-label-text">English</span> </label> <div class="vector-dropdown-content"> <div id="p-variants" class="vector-menu mw-portlet mw-portlet-variants emptyPortlet" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> </ul> </div> </div> </div> </div> </nav> </div> <div id="right-navigation" class="vector-collapsible"> <nav aria-label="Views"> <div id="p-views" class="vector-menu vector-menu-tabs mw-portlet mw-portlet-views" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="ca-view" class="selected vector-tab-noicon mw-list-item"><a href="/wiki/Precision_Time_Protocol"><span>Read</span></a></li><li id="ca-edit" class="vector-tab-noicon mw-list-item"><a href="/w/index.php?title=Precision_Time_Protocol&action=edit" title="Edit this page [e]" accesskey="e"><span>Edit</span></a></li><li id="ca-history" class="vector-tab-noicon mw-list-item"><a href="/w/index.php?title=Precision_Time_Protocol&action=history" title="Past revisions of this page [h]" accesskey="h"><span>View history</span></a></li> </ul> </div> </div> </nav> <nav class="vector-page-tools-landmark" aria-label="Page tools"> <div id="vector-page-tools-dropdown" class="vector-dropdown vector-page-tools-dropdown" > <input type="checkbox" id="vector-page-tools-dropdown-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-tools-dropdown" class="vector-dropdown-checkbox " aria-label="Tools" > <label id="vector-page-tools-dropdown-label" for="vector-page-tools-dropdown-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet" aria-hidden="true" ><span class="vector-dropdown-label-text">Tools</span> </label> <div class="vector-dropdown-content"> <div id="vector-page-tools-unpinned-container" class="vector-unpinned-container"> <div id="vector-page-tools" class="vector-page-tools vector-pinnable-element"> <div class="vector-pinnable-header vector-page-tools-pinnable-header vector-pinnable-header-unpinned" data-feature-name="page-tools-pinned" data-pinnable-element-id="vector-page-tools" data-pinned-container-id="vector-page-tools-pinned-container" data-unpinned-container-id="vector-page-tools-unpinned-container" > <div class="vector-pinnable-header-label">Tools</div> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-pin-button" data-event-name="pinnable-header.vector-page-tools.pin">move to sidebar</button> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-unpin-button" data-event-name="pinnable-header.vector-page-tools.unpin">hide</button> </div> <div id="p-cactions" class="vector-menu mw-portlet mw-portlet-cactions emptyPortlet vector-has-collapsible-items" title="More options" > <div class="vector-menu-heading"> Actions </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="ca-more-view" class="selected vector-more-collapsible-item mw-list-item"><a href="/wiki/Precision_Time_Protocol"><span>Read</span></a></li><li id="ca-more-edit" class="vector-more-collapsible-item mw-list-item"><a href="/w/index.php?title=Precision_Time_Protocol&action=edit" title="Edit this page [e]" accesskey="e"><span>Edit</span></a></li><li id="ca-more-history" class="vector-more-collapsible-item mw-list-item"><a href="/w/index.php?title=Precision_Time_Protocol&action=history"><span>View history</span></a></li> </ul> </div> </div> <div id="p-tb" class="vector-menu mw-portlet mw-portlet-tb" > <div class="vector-menu-heading"> General </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="t-whatlinkshere" class="mw-list-item"><a href="/wiki/Special:WhatLinksHere/Precision_Time_Protocol" title="List of all English Wikipedia pages containing links to this page [j]" accesskey="j"><span>What links here</span></a></li><li id="t-recentchangeslinked" class="mw-list-item"><a href="/wiki/Special:RecentChangesLinked/Precision_Time_Protocol" rel="nofollow" title="Recent changes in pages linked from this page [k]" accesskey="k"><span>Related changes</span></a></li><li id="t-upload" class="mw-list-item"><a href="/wiki/Wikipedia:File_Upload_Wizard" title="Upload files [u]" accesskey="u"><span>Upload file</span></a></li><li id="t-specialpages" class="mw-list-item"><a href="/wiki/Special:SpecialPages" title="A list of all special pages [q]" accesskey="q"><span>Special pages</span></a></li><li id="t-permalink" class="mw-list-item"><a href="/w/index.php?title=Precision_Time_Protocol&oldid=1247519903" title="Permanent link to this revision of this page"><span>Permanent link</span></a></li><li id="t-info" class="mw-list-item"><a href="/w/index.php?title=Precision_Time_Protocol&action=info" title="More information about this page"><span>Page information</span></a></li><li id="t-cite" class="mw-list-item"><a href="/w/index.php?title=Special:CiteThisPage&page=Precision_Time_Protocol&id=1247519903&wpFormIdentifier=titleform" title="Information on how to cite this page"><span>Cite this page</span></a></li><li id="t-urlshortener" class="mw-list-item"><a href="/w/index.php?title=Special:UrlShortener&url=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FPrecision_Time_Protocol"><span>Get shortened URL</span></a></li><li id="t-urlshortener-qrcode" class="mw-list-item"><a href="/w/index.php?title=Special:QrCode&url=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FPrecision_Time_Protocol"><span>Download QR code</span></a></li> </ul> </div> </div> <div id="p-coll-print_export" class="vector-menu mw-portlet mw-portlet-coll-print_export" > <div class="vector-menu-heading"> Print/export </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="coll-download-as-rl" class="mw-list-item"><a href="/w/index.php?title=Special:DownloadAsPdf&page=Precision_Time_Protocol&action=show-download-screen" title="Download this page as a PDF file"><span>Download as PDF</span></a></li><li id="t-print" class="mw-list-item"><a href="/w/index.php?title=Precision_Time_Protocol&printable=yes" title="Printable version of this page [p]" accesskey="p"><span>Printable version</span></a></li> </ul> </div> </div> <div id="p-wikibase-otherprojects" class="vector-menu mw-portlet mw-portlet-wikibase-otherprojects" > <div class="vector-menu-heading"> In other projects </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="t-wikibase" class="wb-otherproject-link wb-otherproject-wikibase-dataitem mw-list-item"><a href="https://www.wikidata.org/wiki/Special:EntityPage/Q1143243" title="Structured data on this page hosted by Wikidata [g]" accesskey="g"><span>Wikidata item</span></a></li> </ul> </div> </div> </div> </div> </div> </div> </nav> </div> </div> </div> <div class="vector-column-end"> <div class="vector-sticky-pinned-container"> <nav class="vector-page-tools-landmark" aria-label="Page tools"> <div id="vector-page-tools-pinned-container" class="vector-pinned-container"> </div> </nav> <nav class="vector-appearance-landmark" aria-label="Appearance"> <div id="vector-appearance-pinned-container" class="vector-pinned-container"> <div id="vector-appearance" class="vector-appearance vector-pinnable-element"> <div class="vector-pinnable-header vector-appearance-pinnable-header vector-pinnable-header-pinned" data-feature-name="appearance-pinned" data-pinnable-element-id="vector-appearance" data-pinned-container-id="vector-appearance-pinned-container" data-unpinned-container-id="vector-appearance-unpinned-container" > <div class="vector-pinnable-header-label">Appearance</div> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-pin-button" data-event-name="pinnable-header.vector-appearance.pin">move to sidebar</button> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-unpin-button" data-event-name="pinnable-header.vector-appearance.unpin">hide</button> </div> </div> </div> </nav> </div> </div> <div id="bodyContent" class="vector-body" aria-labelledby="firstHeading" data-mw-ve-target-container> <div class="vector-body-before-content"> <div class="mw-indicators"> </div> <div id="siteSub" class="noprint">From Wikipedia, the free encyclopedia</div> </div> <div id="contentSub"><div id="mw-content-subtitle"><span class="mw-redirectedfrom">(Redirected from <a href="/w/index.php?title=IEEE_802.1AS&redirect=no" class="mw-redirect" title="IEEE 802.1AS">IEEE 802.1AS</a>)</span></div></div> <div id="mw-content-text" class="mw-body-content"><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none">Network time synchronization protocol</div> <p class="mw-empty-elt"> </p><p>The <b>Precision Time Protocol</b> (<b>PTP</b>) is a <a href="/wiki/Protocol_(computing)" class="mw-redirect" title="Protocol (computing)">protocol</a> for <a href="/wiki/Clock_synchronization" title="Clock synchronization">clock synchronization</a> throughout a <a href="/wiki/Computer_network" title="Computer network">computer network</a> with relatively high <a href="/wiki/Accuracy_and_precision" title="Accuracy and precision">precision</a> and therefore <i>potentially</i> high accuracy. In a <a href="/wiki/Local_area_network" title="Local area network">local area network</a> (LAN), accuracy can be sub-microsecond – making it suitable for measurement and control systems.<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> PTP is used to synchronize <a href="/wiki/Financial_transaction" title="Financial transaction">financial transactions</a>, <a href="/wiki/Mobile_phone_tower" class="mw-redirect" title="Mobile phone tower">mobile phone tower</a> transmissions, sub-sea <a href="/wiki/Acoustic_array" class="mw-redirect" title="Acoustic array">acoustic arrays</a>, and networks that require precise timing but lack access to <a href="/wiki/Satellite_navigation" title="Satellite navigation">satellite navigation</a> signals.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="Seems an overly bold claim that all such systems use PTP or a low value (not notable) claim if only some do (September 2024)">citation needed</span></a></i>]</sup> </p><p>The first version of PTP, <b>IEEE 1588-2002</b>, was published in 2002. <b>IEEE 1588-2008</b>, also known as PTP Version 2, is not <a href="/wiki/Backward_compatible" class="mw-redirect" title="Backward compatible">backward compatible</a> with the 2002 version. <b>IEEE 1588-2019</b> was published in November 2019 and includes backward-compatible improvements to the 2008 publication. IEEE 1588-2008 includes a <i>profile</i> concept defining PTP operating parameters and options. Several profiles have been defined for applications including <a href="/wiki/Telecommunications" title="Telecommunications">telecommunications</a>, <a href="/wiki/Electric_power_distribution" title="Electric power distribution">electric power distribution</a> and <a href="/wiki/Audiovisual" title="Audiovisual">audiovisual</a> uses. <b><style data-mw-deduplicate="TemplateStyles:r1238216509">.mw-parser-output .vanchor>:target~.vanchor-text{background-color:#b1d2ff}@media screen{html.skin-theme-clientpref-night .mw-parser-output .vanchor>:target~.vanchor-text{background-color:#0f4dc9}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .vanchor>:target~.vanchor-text{background-color:#0f4dc9}}</style><span class="vanchor"><span id="IEEE_802.1AS"></span><span class="vanchor-text">IEEE 802.1AS</span></span></b> is an adaptation of PTP, called gPTP, for use with <a href="/wiki/Audio_Video_Bridging" title="Audio Video Bridging">Audio Video Bridging</a> (AVB) and <a href="/wiki/Time-Sensitive_Networking" title="Time-Sensitive Networking">Time-Sensitive Networking</a> (TSN). </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="History">History</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Precision_Time_Protocol&action=edit&section=1" title="Edit section: History"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>According to John Eidson, who led the IEEE 1588-2002 standardization effort, "IEEE 1588 is designed to fill a niche not well served by either of the two dominant protocols, <a href="/wiki/Network_Time_Protocol" title="Network Time Protocol">NTP</a> and <a href="/wiki/GPS" class="mw-redirect" title="GPS">GPS</a>. IEEE 1588 is designed for local systems requiring accuracies beyond those attainable using NTP. It is also designed for applications that cannot bear the cost of a <a href="/wiki/GPS_receiver" class="mw-redirect" title="GPS receiver">GPS receiver</a> at each node, or for which GPS signals are inaccessible."<sup id="cite_ref-Eidson_2-0" class="reference"><a href="#cite_note-Eidson-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> </p><p>PTP was originally defined in the IEEE 1588-2002 standard, officially entitled <i>Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems</i>, and published in 2002. In 2008, IEEE 1588-2008 was released as a revised standard; also known as PTP version 2 (PTPv2), it improves accuracy, precision and robustness but is not <a href="/wiki/Backward_compatible" class="mw-redirect" title="Backward compatible">backward compatible</a> with the original 2002 version.<sup id="cite_ref-Eidson2_3-0" class="reference"><a href="#cite_note-Eidson2-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> IEEE 1588-2019 was published in November 2019,<sup id="cite_ref-4" class="reference"><a href="#cite_note-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> is informally known as <i>PTPv2.1</i> and includes backwards-compatible improvements to the 2008 publication.<sup id="cite_ref-Arnold_2017_5-0" class="reference"><a href="#cite_note-Arnold_2017-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Architecture">Architecture</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Precision_Time_Protocol&action=edit&section=2" title="Edit section: Architecture"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The IEEE 1588 standards describe a <a href="/wiki/Hierarchy" title="Hierarchy">hierarchical</a> <a href="/wiki/Master/slave_(technology)" class="mw-redirect" title="Master/slave (technology)">master–slave architecture</a> for clock <a href="/wiki/Distributed_computing" title="Distributed computing">distribution</a> consisting of one or more <a href="/wiki/Network_segment" title="Network segment">network segments</a> and one or more clocks. An <i>ordinary clock</i> is a device with a single network connection that is either the source of or the destination for a synchronization reference. A source is called a <i>leader</i>, a.k.a. master, and a destination is called a <i>follower</i>, a.k.a. slave. A <i>boundary clock</i> has multiple network connections and synchronizes one network segment to another. A single, synchronization leader is selected, a.k.a. elected, for each network segment. The root timing reference is called the <i>grandmaster</i>.<sup id="cite_ref-6" class="reference"><a href="#cite_note-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> </p><p>A relatively simple PTP architecture consists of ordinary clocks on a single-segment network with no boundary clocks. A grandmaster is elected and all other clocks synchronize to it. </p><p>IEEE 1588-2008 introduces a clock associated with network equipment used to convey PTP messages. The <i>transparent clock</i> modifies PTP messages as they pass through the device.<sup id="cite_ref-TI2013_7-0" class="reference"><a href="#cite_note-TI2013-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> <a href="/wiki/Timestamps" class="mw-redirect" title="Timestamps">Timestamps</a> in the messages are corrected for time spent traversing the network equipment. This scheme improves distribution accuracy by compensating for <a href="/wiki/Packet_delay_variation" title="Packet delay variation">delivery variability</a> across the network. </p><p>PTP typically uses the same <a href="/wiki/Epoch_(computing)" title="Epoch (computing)">epoch</a> as <a href="/wiki/Unix_time" title="Unix time">Unix time</a> (start of 1 January 1970).<sup id="cite_ref-9" class="reference"><a href="#cite_note-9"><span class="cite-bracket">[</span>a<span class="cite-bracket">]</span></a></sup> While the Unix time is based on <a href="/wiki/Coordinated_Universal_Time" title="Coordinated Universal Time">Coordinated Universal Time</a> (UTC) and is subject to <a href="/wiki/Leap_second" title="Leap second">leap seconds</a>, PTP is based on <a href="/wiki/International_Atomic_Time" title="International Atomic Time">International Atomic Time</a> (TAI). The PTP grandmaster communicates the current offset between UTC and TAI, so that UTC can be computed from the received PTP time. </p> <div class="mw-heading mw-heading2"><h2 id="Protocol_details">Protocol details</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Precision_Time_Protocol&action=edit&section=3" title="Edit section: Protocol details"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Synchronization and management of a PTP system is achieved through the exchange of messages across the communications medium. To this end, PTP uses the following message types. </p> <ul><li><i>Sync</i>, <i>Follow_Up</i>, <i>Delay_Req</i> and <i>Delay_Resp</i> messages are used by <i>ordinary</i> and <i>boundary</i> clocks and communicate time-related information used to synchronize clocks across the network.</li> <li><i>Pdelay_Req</i>, <i>Pdelay_Resp</i> and <i>Pdelay_Resp_Follow_Up</i> are used by <i>transparent</i> clocks to measure delays across the communications medium so that they can be compensated for by the system. <i>Transparent</i> clocks and these messages associated with them are not available in original IEEE 1588-2002 PTPv1 standard, and were added in PTPv2.</li> <li><i>Announce</i> messages are used by the <a href="#Best_master_clock_algorithm">best master clock algorithm</a> in IEEE 1588-2008 to build a clock hierarchy and select the <i>grandmaster</i>.<sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite-bracket">[</span>b<span class="cite-bracket">]</span></a></sup></li> <li><i>Management</i> messages are used by <a href="/wiki/Network_management" title="Network management">network management</a> to monitor, configure and maintain a PTP system.</li> <li><i>Signaling</i> messages are used for non-time-critical communications between clocks. Signaling messages were introduced in IEEE 1588-2008.</li></ul> <p>Messages are categorized as <i>event</i> and <i>general</i> messages. <i>Event</i> messages are time-critical in that accuracy in transmission and receipt timestamp accuracy directly affects clock distribution accuracy. <i>Sync</i>, <i>Delay_Req</i>, <i>Pdelay_Req</i> and <i>Pdelay_resp</i> are <i>event</i> messages. <i>General</i> messages are more conventional <a href="/wiki/Protocol_data_units" class="mw-redirect" title="Protocol data units">protocol data units</a> in that the data in these messages is of importance to PTP, but their transmission and receipt timestamps are not. <i>Announce</i>, <i>Follow_Up</i>, <i>Delay_Resp</i>, <i>Pdelay_Resp_Follow_Up</i>, <i>Management</i> and <i>Signaling</i> messages are members of the <i>general</i> message class.<sup id="cite_ref-1588-2008_8-1" class="reference"><a href="#cite_note-1588-2008-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page / location: Clause 6.4">: Clause 6.4 </span></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Message_transport">Message transport</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Precision_Time_Protocol&action=edit&section=4" title="Edit section: Message transport"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>PTP messages may use the <a href="/wiki/User_Datagram_Protocol" title="User Datagram Protocol">User Datagram Protocol</a> over <a href="/wiki/Internet_Protocol" title="Internet Protocol">Internet Protocol</a> (UDP/IP) for transport. IEEE 1588-2002 uses only <a href="/wiki/IPv4" title="IPv4">IPv4</a> transports,<sup id="cite_ref-1588-2002_11-0" class="reference"><a href="#cite_note-1588-2002-11"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page / location: Annex D">: Annex D </span></sup> but this has been extended to include <a href="/wiki/IPv6" title="IPv6">IPv6</a> in IEEE 1588-2008.<sup id="cite_ref-1588-2008_8-2" class="reference"><a href="#cite_note-1588-2008-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page / location: Annex F">: Annex F </span></sup> In IEEE 1588-2002, all PTP messages are sent using <a href="/wiki/Multicast" title="Multicast">multicast</a> messaging, while IEEE 1588-2008 introduced an option for devices to negotiate <a href="/wiki/Unicast" title="Unicast">unicast</a> transmission on a port-by-port basis.<sup id="cite_ref-1588-2008_8-3" class="reference"><a href="#cite_note-1588-2008-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page / location: Clause 16.1">: Clause 16.1 </span></sup> Multicast transmissions use <a href="/wiki/IP_multicast" title="IP multicast">IP multicast</a> addressing, for which multicast group addresses are defined for IPv4 and IPv6 (see table).<sup id="cite_ref-1588-2008_8-4" class="reference"><a href="#cite_note-1588-2008-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page / location: Annex D and E">: Annex D and E </span></sup> Time-critical <i>event</i> messages (Sync, Delay_req, Pdelay_Req and Pdelay_Resp) are sent to <a href="/wiki/Port_number" class="mw-redirect" title="Port number">port number</a> 319. <i>General</i> messages (Announce, Follow_Up, Delay_Resp, Pdelay_Resp_Follow_Up, management and signaling) use port number 320.<sup id="cite_ref-1588-2008_8-5" class="reference"><a href="#cite_note-1588-2008-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page / location: Clause 6.4">: Clause 6.4 </span></sup> </p> <table class="wikitable"> <caption>Multicast group addresses </caption> <tbody><tr> <th>Messages </th> <th>IPv4 </th> <th>IPv6 </th> <th>IEEE 802.3 Ethernet<sup id="cite_ref-1588-2008_8-6" class="reference"><a href="#cite_note-1588-2008-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page / location: Annex F">: Annex F </span></sup><sup id="cite_ref-12" class="reference"><a href="#cite_note-12"><span class="cite-bracket">[</span>c<span class="cite-bracket">]</span></a></sup> </th> <th>Type </th></tr> <tr> <td>All except peer delay messages </td> <td>224.0.1.129<sup id="cite_ref-13" class="reference"><a href="#cite_note-13"><span class="cite-bracket">[</span>d<span class="cite-bracket">]</span></a></sup> </td> <td>FF0x::181<sup id="cite_ref-14" class="reference"><a href="#cite_note-14"><span class="cite-bracket">[</span>e<span class="cite-bracket">]</span></a></sup> </td> <td>01-1B-19-00-00-00<sup id="cite_ref-15" class="reference"><a href="#cite_note-15"><span class="cite-bracket">[</span>f<span class="cite-bracket">]</span></a></sup> </td> <td>Forwardable </td></tr> <tr> <td>Peer delay messages: <i>Pdelay_Req</i>, <i>Pdelay_Resp</i> and <i>Pdelay_Resp_Follow_Up</i><sup id="cite_ref-16" class="reference"><a href="#cite_note-16"><span class="cite-bracket">[</span>g<span class="cite-bracket">]</span></a></sup> </td> <td>224.0.0.107<sup id="cite_ref-17" class="reference"><a href="#cite_note-17"><span class="cite-bracket">[</span>h<span class="cite-bracket">]</span></a></sup> </td> <td>FF02::6B </td> <td>01-80-C2-00-00-0E </td> <td>Non-forwardable </td></tr></tbody></table> <p>In IEEE 1588-2008, encapsulation is also defined for <a href="/wiki/DeviceNet" title="DeviceNet">DeviceNet</a>,<sup id="cite_ref-1588-2008_8-7" class="reference"><a href="#cite_note-1588-2008-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page / location: Annex G">: Annex G </span></sup> <a href="/wiki/ControlNet" title="ControlNet">ControlNet</a><sup id="cite_ref-1588-2008_8-8" class="reference"><a href="#cite_note-1588-2008-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page / location: Annex H">: Annex H </span></sup> and <a href="/wiki/PROFINET" class="mw-redirect" title="PROFINET">PROFINET</a>.<sup id="cite_ref-1588-2008_8-9" class="reference"><a href="#cite_note-1588-2008-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page / location: Annex I">: Annex I </span></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Domains">Domains</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Precision_Time_Protocol&action=edit&section=5" title="Edit section: Domains"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>A domain<sup id="cite_ref-18" class="reference"><a href="#cite_note-18"><span class="cite-bracket">[</span>i<span class="cite-bracket">]</span></a></sup> is an interacting set of clocks that synchronize to one another using PTP. Clocks are assigned to a domain by virtue of the contents of the <i>Subdomain name</i> (IEEE 1588-2002) or the <i>domainNumber</i> (IEEE 1588-2008) fields in PTP messages they receive or generate. Domains allow multiple clock distribution systems to share the same communications medium. </p> <table class="wikitable"> <tbody><tr> <th><i>Subdomain name</i> field contents (<span style="white-space:nowrap">IEEE<span style="margin-left:0.25em">1588-2002</span></span>) </th> <th>IPv4 multicast address<br />(<span style="white-space:nowrap">IEEE<span style="margin-left:0.25em">1588-2002</span></span>)<sup id="cite_ref-19" class="reference"><a href="#cite_note-19"><span class="cite-bracket">[</span>j<span class="cite-bracket">]</span></a></sup> </th> <th><i>domainNumber</i><br />(<span style="white-space:nowrap">IEEE<span style="margin-left:0.25em">1588-2008</span></span>) </th> <th>Notes </th></tr> <tr> <td>_DFLT </td> <td>224.0.1.129 </td> <td>0 </td> <td>Default domain </td></tr> <tr> <td>_ALT1 </td> <td>224.0.1.130 </td> <td>1 </td> <td>Alternate domain 1 </td></tr> <tr> <td>_ALT2 </td> <td>224.0.1.131 </td> <td>2 </td> <td>Alternate domain 2 </td></tr> <tr> <td>_ALT3 </td> <td>224.0.1.132 </td> <td>3 </td> <td>Alternate domain 3 </td></tr> <tr> <td>Application specific up to 15 octets<sup id="cite_ref-1588-2002_11-1" class="reference"><a href="#cite_note-1588-2002-11"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page / location: Clause 6.2.5.1">: Clause 6.2.5.1 </span></sup> </td> <td>224.0.1.130, 131 or 132 as per <a href="/wiki/Hash_function" title="Hash function">hash function</a> on <i>Subdomain name</i><sup id="cite_ref-1588-2002_11-2" class="reference"><a href="#cite_note-1588-2002-11"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page / location: Annex C">: Annex C </span></sup> </td> <td>4 through 127 </td> <td>User-defined domains </td></tr></tbody></table> <div class="mw-heading mw-heading2"><h2 id="Best_master_clock_algorithm">Best master clock algorithm</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Precision_Time_Protocol&action=edit&section=6" title="Edit section: Best master clock algorithm"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The <i>best master clock algorithm</i> (BMCA) performs a distributed selection of the best clock to act as leader based on the following clock properties: </p> <ul><li>Identifier – A universally unique numeric identifier for the clock. This is typically constructed based on a device's <a href="/wiki/MAC_address" title="MAC address">MAC address</a>.</li> <li>Quality – Both versions of IEEE 1588 attempt to quantify clock quality based on expected timing deviation, technology used to implement the clock or location in a <a href="/wiki/Clock_stratum" class="mw-redirect" title="Clock stratum">clock stratum</a> schema, although only V1 (IEEE 1588-2002) knows a data field <i>stratum</i>. PTP V2 (IEEE 1588-2008) defines the overall quality of a clock by using the data fields <i>clockAccuracy</i> and <i>clockClass</i>.</li> <li>Priority – An administratively assigned precedence hint used by the BMCA to help select a <i>grandmaster</i> for the PTP domain. IEEE 1588-2002 used a single <a href="/wiki/Boolean_variable" class="mw-redirect" title="Boolean variable">Boolean variable</a> to indicate precedence. IEEE 1588-2008 features two 8-bit priority fields.</li> <li>Variance – A clock's estimate of its stability based on observation of its performance against the PTP reference.</li></ul> <p>IEEE 1588-2008 uses a hierarchical selection algorithm based on the following properties, in the indicated order:<sup id="cite_ref-1588-2008_8-10" class="reference"><a href="#cite_note-1588-2008-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page / location: Figure 27">: Figure 27 </span></sup> </p> <ol><li>Priority 1 – the user can assign a specific static-designed priority to each clock, preemptively defining a priority among them. Smaller numeric values indicate higher priority.</li> <li>Class – each clock is a member of a given class, each class getting its own priority.</li> <li>Accuracy – precision between clock and UTC, in nanoseconds (ns)</li> <li>Variance – variability of the clock</li> <li>Priority 2 – final-defined priority, defining backup order in case the other criteria were not sufficient. Smaller numeric values indicate higher priority.</li> <li>Unique identifier – MAC address-based selection is used as a tiebreaker when all other properties are equal.</li></ol> <p>IEEE 1588-2002 uses a selection algorithm based on similar properties. </p><p>Clock properties are advertised in IEEE 1588-2002 <i>Sync</i> messages and in IEEE 1588-2008 <i>Announce</i> messages. The current leader transmits this information at regular interval. A clock that considers itself a better leader will transmit this information in order to invoke a change of leader. Once the current leader recognizes the better clock, the current leader stops transmitting <i>Sync</i> messages and associated clock properties (<i>Announce</i> messages in the case of IEEE 1588-2008) and the better clock takes over as leader.<sup id="cite_ref-20" class="reference"><a href="#cite_note-20"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> The BMCA only considers the self-declared quality of clocks and does not take network link quality into consideration.<sup id="cite_ref-21" class="reference"><a href="#cite_note-21"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Synchronization">Synchronization</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Precision_Time_Protocol&action=edit&section=7" title="Edit section: Synchronization"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Via BMCA, PTP selects a source of time for an IEEE 1588 domain and for each network segment in the domain. </p><p>Clocks determine the offset between themselves and their leader.<sup id="cite_ref-IEC_22-0" class="reference"><a href="#cite_note-IEC-22"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> Let the variable <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle t}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>t</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle t}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/65658b7b223af9e1acc877d848888ecdb4466560" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:0.84ex; height:2.009ex;" alt="{\displaystyle t}"></span> represent physical time. For a given follower device, the offset <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle o(t)}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>o</mi> <mo stretchy="false">(</mo> <mi>t</mi> <mo stretchy="false">)</mo> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle o(t)}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/241c8f555002b4df57e79ce53ee57227fafb5f47" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:3.777ex; height:2.843ex;" alt="{\displaystyle o(t)}"></span> at time <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle t}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>t</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle t}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/65658b7b223af9e1acc877d848888ecdb4466560" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:0.84ex; height:2.009ex;" alt="{\displaystyle t}"></span> is defined by: </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \ o(t)=s(t)-m(t)}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mtext> </mtext> <mi>o</mi> <mo stretchy="false">(</mo> <mi>t</mi> <mo stretchy="false">)</mo> <mo>=</mo> <mi>s</mi> <mo stretchy="false">(</mo> <mi>t</mi> <mo stretchy="false">)</mo> <mo>−</mo> <mi>m</mi> <mo stretchy="false">(</mo> <mi>t</mi> <mo stretchy="false">)</mo> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \ o(t)=s(t)-m(t)}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/b31dc1a597e1e906f8dad2dcc855dd632c36d707" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:18.725ex; height:2.843ex;" alt="{\displaystyle \ o(t)=s(t)-m(t)}"></span></dd></dl> <p>where <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle s(t)}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>s</mi> <mo stretchy="false">(</mo> <mi>t</mi> <mo stretchy="false">)</mo> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle s(t)}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/c484de351ba40ccb9a5ad522c29c1aac5686c0df" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:3.739ex; height:2.843ex;" alt="{\displaystyle s(t)}"></span> represents the time measured by the follower clock at physical time <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle t}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>t</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle t}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/65658b7b223af9e1acc877d848888ecdb4466560" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:0.84ex; height:2.009ex;" alt="{\displaystyle t}"></span>, and <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle m(t)}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>m</mi> <mo stretchy="false">(</mo> <mi>t</mi> <mo stretchy="false">)</mo> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle m(t)}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/ea26578dd72bf4dbc3fa391c9feb11eed495699b" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:4.689ex; height:2.843ex;" alt="{\displaystyle m(t)}"></span> represents the time measured by the leader clock at physical time <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle t}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>t</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle t}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/65658b7b223af9e1acc877d848888ecdb4466560" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:0.84ex; height:2.009ex;" alt="{\displaystyle t}"></span>. </p><p>The leader periodically broadcasts the current time as a message to the other clocks. Under IEEE 1588-2002 broadcasts are up to once per second. Under IEEE 1588-2008, up to 10 per second are permitted. </p> <figure class="mw-halign-center" typeof="mw:File/Thumb"><a href="/wiki/File:IEEE1588_1.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/d/db/IEEE1588_1.jpg/549px-IEEE1588_1.jpg" decoding="async" width="549" height="292" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/d/db/IEEE1588_1.jpg 1.5x" data-file-width="620" data-file-height="330" /></a><figcaption>IEEE 1588 synchronization mechanism and delay calculation</figcaption></figure> <p>Each broadcast begins at time <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle T_{1}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>T</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>1</mn> </mrow> </msub> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle T_{1}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/2f304724948a3ef606c4a92459e22b87a954d993" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.412ex; height:2.509ex;" alt="{\displaystyle T_{1}}"></span> with a <i>Sync</i> message sent by the leader to all the clocks in the domain. A clock receiving this message takes note of the local time <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle T_{1}'}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msubsup> <mi>T</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>1</mn> </mrow> <mo>′</mo> </msubsup> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle T_{1}'}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/ac58e22462fc1aeef6a80d3f5649af0a52fcbdc1" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:2.412ex; height:2.843ex;" alt="{\displaystyle T_{1}'}"></span> when this message is received. </p><p>The leader may subsequently send a multicast <i>Follow_Up</i> with accurate <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle T_{1}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>T</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>1</mn> </mrow> </msub> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle T_{1}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/2f304724948a3ef606c4a92459e22b87a954d993" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.412ex; height:2.509ex;" alt="{\displaystyle T_{1}}"></span> timestamp. Not all leaders have the ability to present an accurate timestamp in the <i>Sync</i> message. It is only after the transmission is complete that they are able to retrieve an accurate timestamp for the <i>Sync</i> transmission from their network hardware. Leaders with this limitation use the <i>Follow_Up</i> message to convey <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle T_{1}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>T</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>1</mn> </mrow> </msub> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle T_{1}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/2f304724948a3ef606c4a92459e22b87a954d993" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.412ex; height:2.509ex;" alt="{\displaystyle T_{1}}"></span>. Leaders with PTP capabilities built into their network hardware are able to present an accurate timestamp in the <i>Sync</i> message and do not need to send Follow_Up messages. </p><p>In order to accurately synchronize to their leader, clocks must individually determine the network transit time of the <i>Sync</i> messages. The transit time is determined indirectly by measuring round-trip time from each clock to its leader. The clocks initiate an exchange with their leader designed to measure the transit time <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle d}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>d</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle d}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/e85ff03cbe0c7341af6b982e47e9f90d235c66ab" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.216ex; height:2.176ex;" alt="{\displaystyle d}"></span>. The exchange begins with a clock sending a <i>Delay_Req</i> message at time <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle T_{2}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>T</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> </msub> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle T_{2}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/d1ba5f12fbb0ff766aec6e22148b429373608555" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.412ex; height:2.509ex;" alt="{\displaystyle T_{2}}"></span> to the leader. The leader receives and timestamps the <i>Delay_Req</i> at time <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle T_{2}'}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msubsup> <mi>T</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> <mo>′</mo> </msubsup> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle T_{2}'}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/3be30a7034a4cf80eb1d4f05ac8995d188a5c66e" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:2.412ex; height:2.843ex;" alt="{\displaystyle T_{2}'}"></span> and responds with a <i>Delay_Resp</i> message. The leader includes the timestamp <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle T_{2}'}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msubsup> <mi>T</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> <mo>′</mo> </msubsup> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle T_{2}'}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/3be30a7034a4cf80eb1d4f05ac8995d188a5c66e" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:2.412ex; height:2.843ex;" alt="{\displaystyle T_{2}'}"></span> in the <i>Delay_Resp</i> message. </p><p>Through these exchanges a clock learns <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle T_{1}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>T</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>1</mn> </mrow> </msub> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle T_{1}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/2f304724948a3ef606c4a92459e22b87a954d993" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.412ex; height:2.509ex;" alt="{\displaystyle T_{1}}"></span>, <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle T_{1}'}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msubsup> <mi>T</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>1</mn> </mrow> <mo>′</mo> </msubsup> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle T_{1}'}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/ac58e22462fc1aeef6a80d3f5649af0a52fcbdc1" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:2.412ex; height:2.843ex;" alt="{\displaystyle T_{1}'}"></span>, <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle T_{2}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>T</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> </msub> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle T_{2}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/d1ba5f12fbb0ff766aec6e22148b429373608555" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.412ex; height:2.509ex;" alt="{\displaystyle T_{2}}"></span> and <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle T_{2}'}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msubsup> <mi>T</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> <mo>′</mo> </msubsup> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle T_{2}'}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/3be30a7034a4cf80eb1d4f05ac8995d188a5c66e" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:2.412ex; height:2.843ex;" alt="{\displaystyle T_{2}'}"></span>. </p><p>If <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle d}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mi>d</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle d}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/e85ff03cbe0c7341af6b982e47e9f90d235c66ab" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.216ex; height:2.176ex;" alt="{\displaystyle d}"></span> is the transit time for the <i>Sync</i> message, and <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\tilde {o}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>o</mi> <mo stretchy="false">~</mo> </mover> </mrow> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\tilde {o}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/c204684c345609a5985599bb3961a82744a19023" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.292ex; height:2.176ex;" alt="{\displaystyle {\tilde {o}}}"></span> is the constant offset between leader and follower clocks, then </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \ T_{1}'-T_{1}={\tilde {o}}+d{\text{ and }}\ T_{2}'-T_{2}=-{\tilde {o}}+d}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mtext> </mtext> <msubsup> <mi>T</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>1</mn> </mrow> <mo>′</mo> </msubsup> <mo>−</mo> <msub> <mi>T</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>1</mn> </mrow> </msub> <mo>=</mo> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>o</mi> <mo stretchy="false">~</mo> </mover> </mrow> </mrow> <mo>+</mo> <mi>d</mi> <mrow class="MJX-TeXAtom-ORD"> <mtext> and </mtext> </mrow> <mtext> </mtext> <msubsup> <mi>T</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> <mo>′</mo> </msubsup> <mo>−</mo> <msub> <mi>T</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> </msub> <mo>=</mo> <mo>−</mo> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>o</mi> <mo stretchy="false">~</mo> </mover> </mrow> </mrow> <mo>+</mo> <mi>d</mi> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle \ T_{1}'-T_{1}={\tilde {o}}+d{\text{ and }}\ T_{2}'-T_{2}=-{\tilde {o}}+d}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/bfa91ba13375614a95bf79703b0ff95548ff08e3" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:40.099ex; height:2.843ex;" alt="{\displaystyle \ T_{1}'-T_{1}={\tilde {o}}+d{\text{ and }}\ T_{2}'-T_{2}=-{\tilde {o}}+d}"></span></dd></dl> <p>Combining the above two equations, we find that </p> <dl><dd><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\tilde {o}}={\frac {1}{2}}(T_{1}'-T_{1}-T_{2}'+T_{2})}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>o</mi> <mo stretchy="false">~</mo> </mover> </mrow> </mrow> <mo>=</mo> <mrow class="MJX-TeXAtom-ORD"> <mfrac> <mn>1</mn> <mn>2</mn> </mfrac> </mrow> <mo stretchy="false">(</mo> <msubsup> <mi>T</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>1</mn> </mrow> <mo>′</mo> </msubsup> <mo>−</mo> <msub> <mi>T</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>1</mn> </mrow> </msub> <mo>−</mo> <msubsup> <mi>T</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> <mo>′</mo> </msubsup> <mo>+</mo> <msub> <mi>T</mi> <mrow class="MJX-TeXAtom-ORD"> <mn>2</mn> </mrow> </msub> <mo stretchy="false">)</mo> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\tilde {o}}={\frac {1}{2}}(T_{1}'-T_{1}-T_{2}'+T_{2})}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/018b5557d5e574ab310648a27acad17b2439e0da" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.838ex; width:26.366ex; height:5.176ex;" alt="{\displaystyle {\tilde {o}}={\frac {1}{2}}(T_{1}'-T_{1}-T_{2}'+T_{2})}"></span></dd></dl> <p>The clock now knows the offset <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\tilde {o}}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <mrow class="MJX-TeXAtom-ORD"> <mrow class="MJX-TeXAtom-ORD"> <mover> <mi>o</mi> <mo stretchy="false">~</mo> </mover> </mrow> </mrow> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle {\tilde {o}}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/c204684c345609a5985599bb3961a82744a19023" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.292ex; height:2.176ex;" alt="{\displaystyle {\tilde {o}}}"></span> during this transaction and can correct itself by this amount to bring it into agreement with their leader. </p><p>One assumption is that this exchange of messages happens over a period of time so small that this offset can safely be considered constant over that period. Another assumption is that the transit time of a message going from the leader to a follower is equal to the transit time of a message going from the follower to the leader. Finally, it is assumed that both the leader and follower can accurately measure the time they send or receive a message. The degree to which these assumptions hold true determines the accuracy of the clock at the follower device.<sup id="cite_ref-1588-2008_8-11" class="reference"><a href="#cite_note-1588-2008-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page / location: Clause 6.2">: Clause 6.2 </span></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Optional_features">Optional features</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Precision_Time_Protocol&action=edit&section=8" title="Edit section: Optional features"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>IEEE 1588-2008 standard lists the following set of features that implementations may choose to support: </p> <ul><li>Alternate Time-Scale</li> <li>Grand Master Cluster</li> <li>Unicast Masters</li> <li>Alternate Master</li> <li>Path Trace</li></ul> <p>IEEE 1588-2019 adds additional optional and backward-compatible features:<sup id="cite_ref-Arnold_2017_5-1" class="reference"><a href="#cite_note-Arnold_2017-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> </p> <ul><li>Modular transparent clocks</li> <li>Special PTP ports to interface with transports with built-in time distribution</li> <li>Unicast <i>Delay_Req</i> and <i>Delay_Resp</i> messages</li> <li>Manual port configuration overriding BMCA</li> <li>Asymmetry calibration</li> <li>Ability to utilize a physical layer frequency reference (e.g. <a href="/wiki/Synchronous_Ethernet" title="Synchronous Ethernet">Synchronous Ethernet</a>)</li> <li>Profile isolation</li> <li>Inter-domain interactions</li> <li>Security TLV for integrity checking</li> <li>Standard performance reporting metrics</li> <li>Slave port monitoring</li></ul> <div class="mw-heading mw-heading2"><h2 id="Related_initiatives">Related initiatives</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Precision_Time_Protocol&action=edit&section=9" title="Edit section: Related initiatives"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li>The <i>International IEEE Symposium on Precision Clock Synchronization for Measurement, Control and Communication</i> (ISPCS) is an IEEE-organized annual event that includes a <a href="/wiki/Plugtest" title="Plugtest">plugtest</a> and a conference program with paper and poster presentations, tutorials and discussions covering several aspects of PTP.<sup id="cite_ref-23" class="reference"><a href="#cite_note-23"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup></li> <li>The Institute of Embedded Systems (InES) of the <a href="/wiki/Zurich_University_of_Applied_Sciences/ZHAW" title="Zurich University of Applied Sciences/ZHAW">Zurich University of Applied Sciences/ZHAW</a> is addressing the practical implementation and application of PTP.</li> <li>IEEE 1588 is a key technology in the <a href="/wiki/LXI" class="mw-redirect" title="LXI">LXI</a> Standard for Test and Measurement communication and control.</li> <li>IEEE 802.1AS-2011 is part of the IEEE <a href="/wiki/Audio_Video_Bridging" title="Audio Video Bridging">Audio Video Bridging</a> (AVB) group of standards.<sup id="cite_ref-24" class="reference"><a href="#cite_note-24"><span class="cite-bracket">[</span>k<span class="cite-bracket">]</span></a></sup> It specifies a profile for use of IEEE 1588-2008 for time synchronization over a virtual bridged local area network as defined by <a href="/wiki/IEEE_802.1Q" title="IEEE 802.1Q">IEEE 802.1Q</a>. In particular, 802.1AS defines how <a href="/wiki/IEEE_802.3" title="IEEE 802.3">IEEE 802.3</a> (<a href="/wiki/Ethernet" title="Ethernet">Ethernet</a>), <a href="/wiki/IEEE_802.11" title="IEEE 802.11">IEEE 802.11</a> (<a href="/wiki/Wi-Fi" title="Wi-Fi">Wi-Fi</a>), and <a href="/wiki/Multimedia_over_Coax_Alliance" title="Multimedia over Coax Alliance">MoCA</a> can all be parts of the same PTP timing domain.<sup id="cite_ref-25" class="reference"><a href="#cite_note-25"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup></li> <li><a href="/wiki/SMPTE_2059" title="SMPTE 2059">SMPTE 2059</a>-2 is a PTP profile for use in synchronization of broadcast media systems.<sup id="cite_ref-26" class="reference"><a href="#cite_note-26"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup></li> <li>The <a href="/wiki/AES67" title="AES67">AES67</a> audio networking interoperability standard includes a PTPv2 profile compatible with SMPTE ST2059-2.<sup id="cite_ref-27" class="reference"><a href="#cite_note-27"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup></li> <li><a href="/wiki/Dante_(networking)" title="Dante (networking)">Dante</a> uses PTPv1 for synchronization.<sup id="cite_ref-coveloz2016_28-0" class="reference"><a href="#cite_note-coveloz2016-28"><span class="cite-bracket">[</span>17<span class="cite-bracket">]</span></a></sup></li> <li><a href="/wiki/Q-LAN" title="Q-LAN">Q-LAN</a><sup id="cite_ref-29" class="reference"><a href="#cite_note-29"><span class="cite-bracket">[</span>18<span class="cite-bracket">]</span></a></sup> and <a href="/wiki/Ravenna_(networking)" title="Ravenna (networking)">RAVENNA</a><sup id="cite_ref-coveloz2016_28-1" class="reference"><a href="#cite_note-coveloz2016-28"><span class="cite-bracket">[</span>17<span class="cite-bracket">]</span></a></sup> use PTPv2 for time synchronization.</li> <li><a href="/wiki/The_White_Rabbit_Project" class="mw-redirect" title="The White Rabbit Project">The White Rabbit Project</a> combines <a href="/wiki/Synchronous_Ethernet" title="Synchronous Ethernet">Synchronous Ethernet</a> and PTP.</li> <li><a href="/wiki/Precision_Time_Protocol_Industry_Profile" title="Precision Time Protocol Industry Profile">Precision Time Protocol Industry Profile</a> PTP profiles (L2P2P and L3E2E) for industrial automation in IEC 62439-3</li> <li><a href="/wiki/IEC/IEEE_61850-9-3" title="IEC/IEEE 61850-9-3">IEC/IEEE 61850-9-3</a> PTP profile for substation automation adopted by IEC 61850</li> <li><a href="/wiki/Parallel_Redundancy_Protocol" title="Parallel Redundancy Protocol">Parallel Redundancy Protocol</a> use of PTP profiles (L2P2P and L3E2E) for industrial automation in parallel networks</li> <li>PTP is being studied to be applied as a secure time synchronization protocol in power systems' Wide Area Monitoring<sup id="cite_ref-30" class="reference"><a href="#cite_note-30"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup></li></ul> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Precision_Time_Protocol&action=edit&section=10" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/List_of_PTP_implementations" title="List of PTP implementations">List of PTP implementations</a> – Systems supporting Precision Time Protocol</li> <li><a href="/wiki/Real-time_communication" title="Real-time communication">Real-time communication</a> – Protocols and communication hardware that give real-time guarantees</li></ul> <div class="mw-heading mw-heading2"><h2 id="Notes">Notes</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Precision_Time_Protocol&action=edit&section=11" title="Edit section: Notes"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist reflist-lower-alpha"> <div class="mw-references-wrap mw-references-columns"><ol class="references"> <li id="cite_note-9"><span class="mw-cite-backlink"><b><a href="#cite_ref-9">^</a></b></span> <span class="reference-text">The profile capability under IEEE 1588-2008 allows the use of application-specific epochs.<sup id="cite_ref-1588-2008_8-0" class="reference"><a href="#cite_note-1588-2008-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup><sup class="reference nowrap"><span title="Page / location: Annex B">: Annex B </span></sup></span> </li> <li id="cite_note-10"><span class="mw-cite-backlink"><b><a href="#cite_ref-10">^</a></b></span> <span class="reference-text">In IEEE 1588-2002, information carried by <i>Announce</i> messages is carried in the <i>Sync</i> messages. In IEEE 1588-2008, the <i>Sync</i> message has been optimized and this information is no longer carried here.</span> </li> <li id="cite_note-12"><span class="mw-cite-backlink"><b><a href="#cite_ref-12">^</a></b></span> <span class="reference-text">PTP over bare IEEE 802.3 Ethernet using <a href="/wiki/Ethertype" class="mw-redirect" title="Ethertype">Ethertype</a> 0x88F7</span> </li> <li id="cite_note-13"><span class="mw-cite-backlink"><b><a href="#cite_ref-13">^</a></b></span> <span class="reference-text">IEEE 1588-2002 non-default domains use destination addresses 224.0.1.130 through 224.0.1.132 (see <a href="#Domains">#Domains</a>).</span> </li> <li id="cite_note-14"><span class="mw-cite-backlink"><b><a href="#cite_ref-14">^</a></b></span> <span class="reference-text">Where <i>x</i> is the address scope (2 for link-local) as per RFC 2373 (see <a href="/wiki/Multicast_address#IPv6" title="Multicast address">IPv6 multicast address</a>)</span> </li> <li id="cite_note-15"><span class="mw-cite-backlink"><b><a href="#cite_ref-15">^</a></b></span> <span class="reference-text">In some PTP applications it is permissible to send all PTP messages to 01-1B-19-00-00-00</span> </li> <li id="cite_note-16"><span class="mw-cite-backlink"><b><a href="#cite_ref-16">^</a></b></span> <span class="reference-text">Peer delay messages are intended to propagate to the immediately connected neighbor. The multicast addresses for these messages are designed to be link-local in scope and are not passed through a <a href="/wiki/Router_(computing)" title="Router (computing)">router</a>. IEEE 1588-2008 also recommends setting <a href="/wiki/Time_to_live" title="Time to live">time to live</a> to 1 (IPv4) or hop limit to 0 (IPv6) as further insurance that the messages will not be routed.</span> </li> <li id="cite_note-17"><span class="mw-cite-backlink"><b><a href="#cite_ref-17">^</a></b></span> <span class="reference-text">Peer delay messaging is not present in IEEE 1588-2002</span> </li> <li id="cite_note-18"><span class="mw-cite-backlink"><b><a href="#cite_ref-18">^</a></b></span> <span class="reference-text">IEEE 1588-2002 defines a <i>domain</i> as any interconnected set of clocks (regardless of whether they synchronized to one another) and uses <i>subdomain</i> to refer to what is known as a <i>domain</i> in IEEE 1588-2008.</span> </li> <li id="cite_note-19"><span class="mw-cite-backlink"><b><a href="#cite_ref-19">^</a></b></span> <span class="reference-text">IEEE 1588-2008 uses 224.0.1.129 as the address for all multicast messages.</span> </li> <li id="cite_note-24"><span class="mw-cite-backlink"><b><a href="#cite_ref-24">^</a></b></span> <span class="reference-text">AVB is further extended by the IEEE 802.1 <a href="/wiki/Time-Sensitive_Networking" title="Time-Sensitive Networking">Time-Sensitive Networking</a> (TSN) Task Group.</span> </li> </ol></div></div> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Precision_Time_Protocol&action=edit&section=12" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239543626"><div class="reflist"> <div class="mw-references-wrap mw-references-columns"><ol class="references"> <li id="cite_note-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-1">^</a></b></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><cite id="CITEREFEidson2005" class="citation web cs1">Eidson, John (10 October 2005). <a rel="nofollow" class="external text" href="https://www.nist.gov/document/tutorial-basicpdf">"IEEE-1588 Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems, a Tutorial"</a>. National Institute of Standards and Technology (NIST).</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=IEEE-1588+Standard+for+a+Precision+Clock+Synchronization+Protocol+for+Networked+Measurement+and+Control+Systems%2C+a+Tutorial&rft.pub=National+Institute+of+Standards+and+Technology+%28NIST%29&rft.date=2005-10-10&rft.aulast=Eidson&rft.aufirst=John&rft_id=https%3A%2F%2Fwww.nist.gov%2Fdocument%2Ftutorial-basicpdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3APrecision+Time+Protocol" class="Z3988"></span></span> </li> <li id="cite_note-Eidson-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-Eidson_2-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFEidson2006" class="citation book cs1">Eidson, John C. (April 2006). <i>Measurement, Control and Communication Using IEEE 1588</i>. <a href="/wiki/Springer_Science%2BBusiness_Media" title="Springer Science+Business Media">Springer</a>. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-1-84628-250-8" title="Special:BookSources/978-1-84628-250-8"><bdi>978-1-84628-250-8</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Measurement%2C+Control+and+Communication+Using+IEEE+1588&rft.pub=Springer&rft.date=2006-04&rft.isbn=978-1-84628-250-8&rft.aulast=Eidson&rft.aufirst=John+C.&rfr_id=info%3Asid%2Fen.wikipedia.org%3APrecision+Time+Protocol" class="Z3988"></span></span> </li> <li id="cite_note-Eidson2-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-Eidson2_3-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFEidson2006" class="citation web cs1">Eidson, John (2 October 2006). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20100331083017/http://ieee1588.nist.gov/2006%20IEEE1588%20Agenda/Eidson_1588_Version%202.pdf">"IEEE 1588 Standard Version 2 - A Tutorial"</a> <span class="cs1-format">(PDF)</span>. Archived from <a rel="nofollow" class="external text" href="http://ieee1588.nist.gov/2006%20IEEE1588%20Agenda/Eidson_1588_Version%202.pdf">the original</a> <span class="cs1-format">(PDF)</span> on 31 March 2010<span class="reference-accessdate">. Retrieved <span class="nowrap">12 June</span> 2008</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=IEEE+1588+Standard+Version+2+-+A+Tutorial&rft.date=2006-10-02&rft.aulast=Eidson&rft.aufirst=John&rft_id=http%3A%2F%2Fieee1588.nist.gov%2F2006%2520IEEE1588%2520Agenda%2FEidson_1588_Version%25202.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3APrecision+Time+Protocol" class="Z3988"></span></span> </li> <li id="cite_note-4"><span class="mw-cite-backlink"><b><a href="#cite_ref-4">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://standards.ieee.org/ieee/1588/6825/">"1588-2019 - IEEE Approved Draft Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems"</a>. IEEE<span class="reference-accessdate">. Retrieved <span class="nowrap">15 February</span> 2020</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=1588-2019+-+IEEE+Approved+Draft+Standard+for+a+Precision+Clock+Synchronization+Protocol+for+Networked+Measurement+and+Control+Systems&rft.pub=IEEE&rft_id=https%3A%2F%2Fstandards.ieee.org%2Fieee%2F1588%2F6825%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3APrecision+Time+Protocol" class="Z3988"></span></span> </li> <li id="cite_note-Arnold_2017-5"><span class="mw-cite-backlink">^ <a href="#cite_ref-Arnold_2017_5-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-Arnold_2017_5-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFDouglas_Arnold2017" class="citation web cs1">Douglas Arnold (24 September 2017). <a rel="nofollow" class="external text" href="https://blog.meinbergglobal.com/2017/09/24/whats-coming-next-edition-ieee-1588/">"What's coming In the Next Edition of IEEE 1588?"</a><span class="reference-accessdate">. Retrieved <span class="nowrap">15 February</span> 2020</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=What%27s+coming+In+the+Next+Edition+of+IEEE+1588%3F&rft.date=2017-09-24&rft.au=Douglas+Arnold&rft_id=https%3A%2F%2Fblog.meinbergglobal.com%2F2017%2F09%2F24%2Fwhats-coming-next-edition-ieee-1588%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3APrecision+Time+Protocol" class="Z3988"></span></span> </li> <li id="cite_note-6"><span class="mw-cite-backlink"><b><a href="#cite_ref-6">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20100527161310/http://ieee1588.nist.gov/terms.htm">"Meanings of common terms used in IEEE 1588"</a>. National Institute of Standards and Technology. Archived from <a rel="nofollow" class="external text" href="http://ieee1588.nist.gov/terms.htm">the original</a> on 27 May 2010<span class="reference-accessdate">. Retrieved <span class="nowrap">19 May</span> 2006</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Meanings+of+common+terms+used+in+IEEE+1588&rft.pub=National+Institute+of+Standards+and+Technology&rft_id=http%3A%2F%2Fieee1588.nist.gov%2Fterms.htm&rfr_id=info%3Asid%2Fen.wikipedia.org%3APrecision+Time+Protocol" class="Z3988"></span></span> </li> <li id="cite_note-TI2013-7"><span class="mw-cite-backlink"><b><a href="#cite_ref-TI2013_7-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.ti.com/lit/an/snla104a/snla104a.pdf">"AN-1838 IEEE 1588 Boundary Clock and Transparent Clock Implementation Using the DP83640"</a> <span class="cs1-format">(PDF)</span>. <i>ti.com</i>. Texas Instruments<span class="reference-accessdate">. Retrieved <span class="nowrap">17 July</span> 2019</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=ti.com&rft.atitle=AN-1838+IEEE+1588+Boundary+Clock+and+Transparent+Clock+Implementation+Using+the+DP83640&rft_id=http%3A%2F%2Fwww.ti.com%2Flit%2Fan%2Fsnla104a%2Fsnla104a.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3APrecision+Time+Protocol" class="Z3988"></span></span> </li> <li id="cite_note-1588-2008-8"><span class="mw-cite-backlink">^ <a href="#cite_ref-1588-2008_8-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-1588-2008_8-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-1588-2008_8-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-1588-2008_8-3"><sup><i><b>d</b></i></sup></a> <a href="#cite_ref-1588-2008_8-4"><sup><i><b>e</b></i></sup></a> <a href="#cite_ref-1588-2008_8-5"><sup><i><b>f</b></i></sup></a> <a href="#cite_ref-1588-2008_8-6"><sup><i><b>g</b></i></sup></a> <a href="#cite_ref-1588-2008_8-7"><sup><i><b>h</b></i></sup></a> <a href="#cite_ref-1588-2008_8-8"><sup><i><b>i</b></i></sup></a> <a href="#cite_ref-1588-2008_8-9"><sup><i><b>j</b></i></sup></a> <a href="#cite_ref-1588-2008_8-10"><sup><i><b>k</b></i></sup></a> <a href="#cite_ref-1588-2008_8-11"><sup><i><b>l</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation cs2"><i>IEEE Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems</i>, <a href="/wiki/IEEE" class="mw-redirect" title="IEEE">IEEE</a>, 24 July 2008, <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1109%2FIEEESTD.2008.4579760">10.1109/IEEESTD.2008.4579760</a>, <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-7381-5400-8" title="Special:BookSources/978-0-7381-5400-8"><bdi>978-0-7381-5400-8</bdi></a></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=IEEE+Standard+for+a+Precision+Clock+Synchronization+Protocol+for+Networked+Measurement+and+Control+Systems&rft.pub=IEEE&rft.date=2008-07-24&rft_id=info%3Adoi%2F10.1109%2FIEEESTD.2008.4579760&rft.isbn=978-0-7381-5400-8&rfr_id=info%3Asid%2Fen.wikipedia.org%3APrecision+Time+Protocol" class="Z3988"></span></span> </li> <li id="cite_note-1588-2002-11"><span class="mw-cite-backlink">^ <a href="#cite_ref-1588-2002_11-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-1588-2002_11-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-1588-2002_11-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation cs2"><i>IEEE Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems</i>, <a href="/wiki/IEEE" class="mw-redirect" title="IEEE">IEEE</a>, 8 November 2002, <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1109%2FIEEESTD.2002.94144">10.1109/IEEESTD.2002.94144</a>, <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-7381-3369-0" title="Special:BookSources/978-0-7381-3369-0"><bdi>978-0-7381-3369-0</bdi></a></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=IEEE+Standard+for+a+Precision+Clock+Synchronization+Protocol+for+Networked+Measurement+and+Control+Systems&rft.pub=IEEE&rft.date=2002-11-08&rft_id=info%3Adoi%2F10.1109%2FIEEESTD.2002.94144&rft.isbn=978-0-7381-3369-0&rfr_id=info%3Asid%2Fen.wikipedia.org%3APrecision+Time+Protocol" class="Z3988"></span></span> </li> <li id="cite_note-20"><span class="mw-cite-backlink"><b><a href="#cite_ref-20">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFWattAchantaAbubakariSagen2014" class="citation cs2">Watt, Steve T.; Achanta, Shankar; Abubakari, Hamza; Sagen, Eric (March 2014), <a rel="nofollow" class="external text" href="https://cdn.selinc.com/assets/Literature/Publications/Technical%20Papers/6650_UnderstandingApplying_SA_20140206_Web3.pdf"><i>Understanding and Applying Precision Time Protocol</i></a> <span class="cs1-format">(PDF)</span><span class="reference-accessdate">, retrieved <span class="nowrap">9 September</span> 2017</span></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Understanding+and+Applying+Precision+Time+Protocol&rft.date=2014-03&rft.aulast=Watt&rft.aufirst=Steve+T.&rft.au=Achanta%2C+Shankar&rft.au=Abubakari%2C+Hamza&rft.au=Sagen%2C+Eric&rft_id=https%3A%2F%2Fcdn.selinc.com%2Fassets%2FLiterature%2FPublications%2FTechnical%2520Papers%2F6650_UnderstandingApplying_SA_20140206_Web3.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3APrecision+Time+Protocol" class="Z3988"></span></span> </li> <li id="cite_note-21"><span class="mw-cite-backlink"><b><a href="#cite_ref-21">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFFSMLabs_Technical_Staff2015" class="citation cs2">FSMLabs Technical Staff (September 2015), <a rel="nofollow" class="external text" href="http://www.fsmlabs.com/news/2015/09/18/socalledbestmasterclock.html"><i>Smart and Dumb PTP Client and the "so-called"Best Master Clock Algorithm</i></a><span class="reference-accessdate">, retrieved <span class="nowrap">17 May</span> 2018</span></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Smart+and+Dumb+PTP+Client+and+the+%22so-called%22Best+Master+Clock+Algorithm&rft.date=2015-09&rft.au=FSMLabs+Technical+Staff&rft_id=http%3A%2F%2Fwww.fsmlabs.com%2Fnews%2F2015%2F09%2F18%2Fsocalledbestmasterclock.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3APrecision+Time+Protocol" class="Z3988"></span></span> </li> <li id="cite_note-IEC-22"><span class="mw-cite-backlink"><b><a href="#cite_ref-IEC_22-0">^</a></b></span> <span class="reference-text"><a href="/wiki/International_standard" title="International standard">International standard</a> <a href="/wiki/IEC" class="mw-redirect" title="IEC">IEC</a> 61588: Precision clock synchronization protocol for networked measurement and control systems. 2004.</span> </li> <li id="cite_note-23"><span class="mw-cite-backlink"><b><a href="#cite_ref-23">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://www.ispcs.org">ISPCS website</a></span> </li> <li id="cite_note-25"><span class="mw-cite-backlink"><b><a href="#cite_ref-25">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFGeoffrey_M._Garner2010" class="citation cs2">Geoffrey M. Garner (28 May 2010), <a rel="nofollow" class="external text" href="https://www.itu.int/dms_pub/itu-t/oth/06/38/T06380000040002PDFE.pdf"><i>IEEE 802.1AS and IEEE 1588</i></a> <span class="cs1-format">(PDF)</span></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=IEEE+802.1AS+and+IEEE+1588&rft.date=2010-05-28&rft.au=Geoffrey+M.+Garner&rft_id=https%3A%2F%2Fwww.itu.int%2Fdms_pub%2Fitu-t%2Foth%2F06%2F38%2FT06380000040002PDFE.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3APrecision+Time+Protocol" class="Z3988"></span></span> </li> <li id="cite_note-26"><span class="mw-cite-backlink"><b><a href="#cite_ref-26">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation cs2"><a rel="nofollow" class="external text" href="https://www.smpte.org/news-events/news-releases/smpte%C2%AE-publishes-first-two-parts-standard-enabling-deployment-ptp-timed"><i>SMPTE Publishes First Two Parts of Standard Enabling Deployment of PTP-Timed Equipment in Existing SDI Plants</i></a>, <a href="/wiki/Society_of_Motion_Picture_and_Television_Engineers" title="Society of Motion Picture and Television Engineers">Society of Motion Picture and Television Engineers</a>, 13 April 2015<span class="reference-accessdate">, retrieved <span class="nowrap">21 May</span> 2015</span></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=SMPTE+Publishes+First+Two+Parts+of+Standard+Enabling+Deployment+of+PTP-Timed+Equipment+in+Existing+SDI+Plants&rft.pub=Society+of+Motion+Picture+and+Television+Engineers&rft.date=2015-04-13&rft_id=https%3A%2F%2Fwww.smpte.org%2Fnews-events%2Fnews-releases%2Fsmpte%25C2%25AE-publishes-first-two-parts-standard-enabling-deployment-ptp-timed&rfr_id=info%3Asid%2Fen.wikipedia.org%3APrecision+Time+Protocol" class="Z3988"></span></span> </li> <li id="cite_note-27"><span class="mw-cite-backlink"><b><a href="#cite_ref-27">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation cs2"><a rel="nofollow" class="external text" href="http://www.aes.org/publications/standards/search.cfm?docID=105"><i>AES-R16-2016: AES Standards Report - PTP parameters for AES67 and SMPTE ST 2059-2 interoperability</i></a>, <a href="/wiki/Audio_Engineering_Society" title="Audio Engineering Society">Audio Engineering Society</a>, 2 May 2016</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=AES-R16-2016%3A+AES+Standards+Report+-+PTP+parameters+for+AES67+and+SMPTE+ST+2059-2+interoperability&rft.pub=Audio+Engineering+Society&rft.date=2016-05-02&rft_id=http%3A%2F%2Fwww.aes.org%2Fpublications%2Fstandards%2Fsearch.cfm%3FdocID%3D105&rfr_id=info%3Asid%2Fen.wikipedia.org%3APrecision+Time+Protocol" class="Z3988"></span></span> </li> <li id="cite_note-coveloz2016-28"><span class="mw-cite-backlink">^ <a href="#cite_ref-coveloz2016_28-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-coveloz2016_28-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><a rel="nofollow" class="external free" href="https://www.smpte.org/sites/default/files/users/user27446/AES67%20for%20Audio%20Production-Background%20Applications%20and%20Challenges.pdf">https://www.smpte.org/sites/default/files/users/user27446/AES67%20for%20Audio%20Production-Background%20Applications%20and%20Challenges.pdf</a> <sup class="noprint Inline-Template"><span style="white-space: nowrap;">[<i><a href="/wiki/Wikipedia:Link_rot" title="Wikipedia:Link rot"><span title=" Dead link tagged February 2022">dead link</span></a></i><span style="visibility:hidden; color:transparent; padding-left:2px">‍</span>]</span></sup></span> </li> <li id="cite_note-29"><span class="mw-cite-backlink"><b><a href="#cite_ref-29">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.luminex.be/improve-your-timekeeping-with-ptpv2/">"PTPv2 Timing protocol in AV networks"</a>. Luminex. 6 June 2017. <q>Q-LAN updated to PTPv2 approximately two years ago.</q></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=PTPv2+Timing+protocol+in+AV+networks&rft.pub=Luminex&rft.date=2017-06-06&rft_id=https%3A%2F%2Fwww.luminex.be%2Fimprove-your-timekeeping-with-ptpv2%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3APrecision+Time+Protocol" class="Z3988"></span></span> </li> <li id="cite_note-30"><span class="mw-cite-backlink"><b><a href="#cite_ref-30">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFPepicielloVaccaro2018" class="citation cs2">Pepiciello, Antonio; Vaccaro, Alfredo (17 December 2018), "A reliable architecture based on Precision Time Protocol for WAMPAC synchronization", <i>2018 AEIT International Annual Conference</i>, <a href="/wiki/IEEE" class="mw-redirect" title="IEEE">IEEE</a>, pp. 1–5, <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.23919%2FAEIT.2018.8577414">10.23919/AEIT.2018.8577414</a>, <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-8-8872-3740-5" title="Special:BookSources/978-8-8872-3740-5"><bdi>978-8-8872-3740-5</bdi></a>, <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:58819556">58819556</a></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=bookitem&rft.atitle=A+reliable+architecture+based+on+Precision+Time+Protocol+for+WAMPAC+synchronization&rft.btitle=2018+AEIT+International+Annual+Conference&rft.pages=1-5&rft.pub=IEEE&rft.date=2018-12-17&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A58819556%23id-name%3DS2CID&rft_id=info%3Adoi%2F10.23919%2FAEIT.2018.8577414&rft.isbn=978-8-8872-3740-5&rft.aulast=Pepiciello&rft.aufirst=Antonio&rft.au=Vaccaro%2C+Alfredo&rfr_id=info%3Asid%2Fen.wikipedia.org%3APrecision+Time+Protocol" class="Z3988"></span></span> </li> </ol></div></div> <div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Precision_Time_Protocol&action=edit&section=13" title="Edit section: External links"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a rel="nofollow" class="external text" href="https://www.nist.gov/el/intelligent-systems-division-73500/ieee-1588">NIST IEEE 1588 site</a></li> <li><a rel="nofollow" class="external text" href="https://web.archive.org/web/20131206102327/http://www.zhaw.ch/en/engineering/institutes-centres/ines/downloads/documents.html">PTP documentation at InES</a></li> <li><a rel="nofollow" class="external text" href="https://www.albedotelecom.com/src/lib/WP-Mobile-PTP.pdf">PTP and Synchronization of LTE mobile networks</a></li> <li><a rel="nofollow" class="external text" href="https://www.albedotelecom.com/src/lib/WP-PTP.pdf">PTP explained under the installation / maintenance point of view</a></li> <li><a rel="nofollow" class="external text" href="https://web.archive.org/web/20110818184219/http://www.belden.com/pdfs/Techpprs/Precision_Clock_Synchronization_WP.pdf">Hirschmann PTP Whitepaper</a></li> <li><a rel="nofollow" class="external text" href="https://www.cisco.com/c/en/us/td/docs/switches/connectedgrid/cgs2520/software/release/12_2_58_ey/configuration/cgs_2520_swcg.html#wp1988925">PTP overview in Cisco CGS 2520 Switch Software Configuration Guide</a></li> <li><a rel="nofollow" class="external text" href="https://web.archive.org/web/20160304192052/http://www.bcit.ca/files/appliedresearch/pdf/ruggedcom_industry.pdf">Perspectives and priorities on RuggedCom Smart Grid Research IEC 61850 Technologies</a></li> <li><a rel="nofollow" class="external text" href="https://web.archive.org/web/20120114222001/http://xn--61850-txen0l.xn--p1ai/wp-content/plugins/downloads-manager/upload/Introduction%20of%20Smart%20Subsltation%20Projects.pdf">Projects with Smart Substation Solution</a></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFMcGheeGoraj2010" class="citation cs2">McGhee, Jim; Goraj, Maciej (2010), "Smart High Voltage Substation Based on IEC 61850 Process Bus and IEEE 1588 Time Synchronization", <i>2010 First IEEE International Conference on Smart Grid Communications</i>, pp. 489–494, <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1109%2FSMARTGRID.2010.5622092">10.1109/SMARTGRID.2010.5622092</a>, <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-1-4244-6510-1" title="Special:BookSources/978-1-4244-6510-1"><bdi>978-1-4244-6510-1</bdi></a>, <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:30638718">30638718</a></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=bookitem&rft.atitle=Smart+High+Voltage+Substation+Based+on+IEC+61850+Process+Bus+and+IEEE+1588+Time+Synchronization&rft.btitle=2010+First+IEEE+International+Conference+on+Smart+Grid+Communications&rft.pages=489-494&rft.date=2010&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A30638718%23id-name%3DS2CID&rft_id=info%3Adoi%2F10.1109%2FSMARTGRID.2010.5622092&rft.isbn=978-1-4244-6510-1&rft.aulast=McGhee&rft.aufirst=Jim&rft.au=Goraj%2C+Maciej&rfr_id=info%3Asid%2Fen.wikipedia.org%3APrecision+Time+Protocol" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFIngramCampbellSchaubLedwich2011" class="citation book cs1">Ingram, D.M.E; Campbell, D.A.; Schaub, P.; Ledwich, G.F. (2011). <a rel="nofollow" class="external text" href="https://eprints.qut.edu.au/41257/">"Test and evaluation system for multi-protocol sampled value protection schemes"</a>. <i>2011 IEEE Trondheim PowerTech</i>. Trondheim, Norway: IEEE. pp. 1–7. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1109%2FPTC.2011.6019243">10.1109/PTC.2011.6019243</a>. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-1-4244-8419-5" title="Special:BookSources/978-1-4244-8419-5"><bdi>978-1-4244-8419-5</bdi></a>. <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:42991214">42991214</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=bookitem&rft.atitle=Test+and+evaluation+system+for+multi-protocol+sampled+value+protection+schemes&rft.btitle=2011+IEEE+Trondheim+PowerTech&rft.place=Trondheim%2C+Norway&rft.pages=1-7&rft.pub=IEEE&rft.date=2011&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A42991214%23id-name%3DS2CID&rft_id=info%3Adoi%2F10.1109%2FPTC.2011.6019243&rft.isbn=978-1-4244-8419-5&rft.aulast=Ingram&rft.aufirst=D.M.E&rft.au=Campbell%2C+D.A.&rft.au=Schaub%2C+P.&rft.au=Ledwich%2C+G.F.&rft_id=https%3A%2F%2Feprints.qut.edu.au%2F41257%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3APrecision+Time+Protocol" class="Z3988"></span></li> <li><a rel="nofollow" class="external text" href="https://safran-navigation-timing.com/solution/white-rabbit-solutions/">The White Rabbit Project PTP</a></li> <li><a rel="nofollow" class="external text" href="https://web.archive.org/web/20170205095756/http://lamspeople.epfl.ch/kirrmann/Pubs/IEC_62439-3/PacWorld_038_043_IEC_IEEE_61850-9-3_September_2016_HK.pdf">IEC&IEEE Precision Time Protocol</a><i>, Pacworld, September 2016</i></li> <li><a rel="nofollow" class="external text" href="https://webstore.iec.ch/publication/24447">IEC 62439-3 Annexes A-E Redundant attachment of clocks and network management</a></li> <li><a rel="nofollow" class="external text" href="https://www.luminex.be/improve-your-timekeeping-with-ptpv2/">PTPv2 Timing protocol in AV networks</a></li> <li><a rel="nofollow" class="external text" href="https://www.fsmlabs.com/news/2016/03/31/singlesource.html">FSMLabs: Single source IEEE PTP 1588 cannot meet financial regulatory standards</a></li></ul> <div class="navbox-styles"><style data-mw-deduplicate="TemplateStyles:r1129693374">.mw-parser-output .hlist dl,.mw-parser-output .hlist ol,.mw-parser-output .hlist ul{margin:0;padding:0}.mw-parser-output .hlist dd,.mw-parser-output .hlist dt,.mw-parser-output .hlist li{margin:0;display:inline}.mw-parser-output .hlist.inline,.mw-parser-output .hlist.inline dl,.mw-parser-output .hlist.inline ol,.mw-parser-output .hlist.inline ul,.mw-parser-output .hlist dl dl,.mw-parser-output .hlist dl ol,.mw-parser-output .hlist dl ul,.mw-parser-output .hlist ol dl,.mw-parser-output .hlist ol ol,.mw-parser-output .hlist ol ul,.mw-parser-output .hlist ul dl,.mw-parser-output .hlist ul ol,.mw-parser-output .hlist ul ul{display:inline}.mw-parser-output .hlist .mw-empty-li{display:none}.mw-parser-output .hlist dt::after{content:": "}.mw-parser-output .hlist dd::after,.mw-parser-output .hlist li::after{content:" · ";font-weight:bold}.mw-parser-output .hlist dd:last-child::after,.mw-parser-output .hlist dt:last-child::after,.mw-parser-output .hlist li:last-child::after{content:none}.mw-parser-output .hlist dd dd:first-child::before,.mw-parser-output .hlist dd dt:first-child::before,.mw-parser-output .hlist dd li:first-child::before,.mw-parser-output .hlist dt dd:first-child::before,.mw-parser-output .hlist dt dt:first-child::before,.mw-parser-output .hlist dt li:first-child::before,.mw-parser-output .hlist li dd:first-child::before,.mw-parser-output .hlist li dt:first-child::before,.mw-parser-output .hlist li li:first-child::before{content:" (";font-weight:normal}.mw-parser-output .hlist dd dd:last-child::after,.mw-parser-output .hlist dd dt:last-child::after,.mw-parser-output .hlist dd li:last-child::after,.mw-parser-output .hlist dt dd:last-child::after,.mw-parser-output .hlist dt dt:last-child::after,.mw-parser-output .hlist dt li:last-child::after,.mw-parser-output .hlist li dd:last-child::after,.mw-parser-output .hlist li dt:last-child::after,.mw-parser-output .hlist li li:last-child::after{content:")";font-weight:normal}.mw-parser-output .hlist ol{counter-reset:listitem}.mw-parser-output .hlist ol>li{counter-increment:listitem}.mw-parser-output .hlist ol>li::before{content:" "counter(listitem)"\a0 "}.mw-parser-output .hlist dd ol>li:first-child::before,.mw-parser-output .hlist dt ol>li:first-child::before,.mw-parser-output .hlist li ol>li:first-child::before{content:" ("counter(listitem)"\a0 "}</style><style data-mw-deduplicate="TemplateStyles:r1236075235">.mw-parser-output .navbox{box-sizing:border-box;border:1px solid #a2a9b1;width:100%;clear:both;font-size:88%;text-align:center;padding:1px;margin:1em auto 0}.mw-parser-output .navbox .navbox{margin-top:0}.mw-parser-output .navbox+.navbox,.mw-parser-output .navbox+.navbox-styles+.navbox{margin-top:-1px}.mw-parser-output .navbox-inner,.mw-parser-output .navbox-subgroup{width:100%}.mw-parser-output .navbox-group,.mw-parser-output .navbox-title,.mw-parser-output .navbox-abovebelow{padding:0.25em 1em;line-height:1.5em;text-align:center}.mw-parser-output .navbox-group{white-space:nowrap;text-align:right}.mw-parser-output .navbox,.mw-parser-output .navbox-subgroup{background-color:#fdfdfd}.mw-parser-output .navbox-list{line-height:1.5em;border-color:#fdfdfd}.mw-parser-output .navbox-list-with-group{text-align:left;border-left-width:2px;border-left-style:solid}.mw-parser-output tr+tr>.navbox-abovebelow,.mw-parser-output tr+tr>.navbox-group,.mw-parser-output tr+tr>.navbox-image,.mw-parser-output tr+tr>.navbox-list{border-top:2px solid #fdfdfd}.mw-parser-output .navbox-title{background-color:#ccf}.mw-parser-output .navbox-abovebelow,.mw-parser-output .navbox-group,.mw-parser-output .navbox-subgroup .navbox-title{background-color:#ddf}.mw-parser-output .navbox-subgroup .navbox-group,.mw-parser-output .navbox-subgroup .navbox-abovebelow{background-color:#e6e6ff}.mw-parser-output .navbox-even{background-color:#f7f7f7}.mw-parser-output .navbox-odd{background-color:transparent}.mw-parser-output .navbox .hlist td dl,.mw-parser-output .navbox .hlist td ol,.mw-parser-output .navbox .hlist td ul,.mw-parser-output .navbox td.hlist dl,.mw-parser-output .navbox td.hlist ol,.mw-parser-output .navbox td.hlist ul{padding:0.125em 0}.mw-parser-output .navbox .navbar{display:block;font-size:100%}.mw-parser-output .navbox-title .navbar{float:left;text-align:left;margin-right:0.5em}body.skin--responsive .mw-parser-output .navbox-image img{max-width:none!important}@media print{body.ns-0 .mw-parser-output .navbox{display:none!important}}</style></div><div role="navigation" class="navbox" aria-labelledby="IEEE_standards" style="padding:3px"><table class="nowraplinks hlist mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><style data-mw-deduplicate="TemplateStyles:r1239400231">.mw-parser-output .navbar{display:inline;font-size:88%;font-weight:normal}.mw-parser-output .navbar-collapse{float:left;text-align:left}.mw-parser-output .navbar-boxtext{word-spacing:0}.mw-parser-output .navbar ul{display:inline-block;white-space:nowrap;line-height:inherit}.mw-parser-output .navbar-brackets::before{margin-right:-0.125em;content:"[ "}.mw-parser-output .navbar-brackets::after{margin-left:-0.125em;content:" ]"}.mw-parser-output .navbar li{word-spacing:-0.125em}.mw-parser-output .navbar a>span,.mw-parser-output .navbar a>abbr{text-decoration:inherit}.mw-parser-output .navbar-mini abbr{font-variant:small-caps;border-bottom:none;text-decoration:none;cursor:inherit}.mw-parser-output .navbar-ct-full{font-size:114%;margin:0 7em}.mw-parser-output .navbar-ct-mini{font-size:114%;margin:0 4em}html.skin-theme-clientpref-night .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}@media(prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}}@media print{.mw-parser-output .navbar{display:none!important}}</style><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:IEEE_standards" title="Template:IEEE standards"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:IEEE_standards" title="Template talk:IEEE standards"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:IEEE_standards" title="Special:EditPage/Template:IEEE standards"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="IEEE_standards" style="font-size:114%;margin:0 4em"><a href="/wiki/IEEE_Standards_Association" title="IEEE Standards Association">IEEE standards</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%">Current</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/IEEE-488" class="mw-redirect" title="IEEE-488">488</a></li> <li><a href="/wiki/IEEE_693" title="IEEE 693">693</a></li> <li><a href="/wiki/Software_quality_assurance" title="Software quality assurance">730</a></li> <li><a href="/wiki/IEEE_754" title="IEEE 754">754</a> <ul><li><a href="/wiki/IEEE_754-2008_revision" title="IEEE 754-2008 revision">Revision</a></li></ul></li> <li><a href="/wiki/IEEE_854-1987" title="IEEE 854-1987">854</a></li> <li><a href="/wiki/Software_configuration_management" title="Software configuration management">828</a></li> <li><a href="/wiki/Software_test_documentation" title="Software test documentation">829</a></li> <li><a href="/wiki/Futurebus" title="Futurebus">896</a></li> <li><a href="/wiki/Single_UNIX_Specification" title="Single UNIX Specification">1003</a></li> <li><a href="/wiki/VMEbus" title="VMEbus">1014</a></li> <li><a href="/wiki/Software_design_description" title="Software design description">1016</a></li> <li><a href="/wiki/VHDL" title="VHDL">1076</a></li> <li><a href="/wiki/JTAG" title="JTAG">1149.1</a></li> <li><a href="/wiki/PILOT" title="PILOT">1154</a></li> <li><a href="/wiki/IEEE_1164" title="IEEE 1164">1164</a></li> <li><a href="/wiki/Open_Firmware" title="Open Firmware">1275</a></li> <li><a href="/wiki/Distributed_Interactive_Simulation" title="Distributed Interactive Simulation">1278</a></li> <li><a href="/wiki/IEEE_1284" title="IEEE 1284">1284</a></li> <li><a href="/wiki/IEEE_1355" title="IEEE 1355">1355</a></li> <li><a href="/wiki/IEEE_1394" title="IEEE 1394">1394</a></li> <li><a href="/wiki/IEEE_1451" title="IEEE 1451">1451</a></li> <li><a href="/wiki/Standard_Delay_Format" title="Standard Delay Format">1497</a></li> <li><a href="/wiki/High-level_architecture" class="mw-redirect" title="High-level architecture">1516</a></li> <li><a href="/wiki/IEEE_1541-2002" class="mw-redirect" title="IEEE 1541-2002">1541</a></li> <li><a href="/wiki/IEEE_1547" title="IEEE 1547">1547</a></li> <li><a href="/wiki/IEEE_1584" title="IEEE 1584">1584</a></li> <li><a class="mw-selflink selflink">1588</a></li> <li><a href="/wiki/Scalable_Coherent_Interface" title="Scalable Coherent Interface">1596</a></li> <li><a href="/wiki/Advanced_Library_Format" title="Advanced Library Format">1603</a></li> <li><a href="/wiki/IEEE_1613" title="IEEE 1613">1613</a></li> <li><a href="/wiki/IEEE_1619" class="mw-redirect" title="IEEE 1619">1619</a></li> <li><a href="/wiki/SystemC" title="SystemC">1666</a></li> <li><a href="/wiki/IEEE_1667" title="IEEE 1667">1667</a></li> <li><a href="/wiki/IEEE_1675-2008" title="IEEE 1675-2008">1675</a></li> <li><a href="/wiki/IP-XACT" title="IP-XACT">1685</a></li> <li><a href="/wiki/IEEE_1722" class="mw-redirect" title="IEEE 1722">1722</a></li> <li><a href="/wiki/IEEE_1733" class="mw-redirect" title="IEEE 1733">1733</a></li> <li><a href="/wiki/SystemVerilog" title="SystemVerilog">1800</a></li> <li><a href="/wiki/Unified_Power_Format" title="Unified Power Format">1801</a></li> <li><a href="/wiki/DNP3" title="DNP3">1815</a></li> <li><a href="/wiki/IEEE_1849" title="IEEE 1849">1849</a></li> <li><a href="/wiki/Property_Specification_Language" title="Property Specification Language">1850</a></li> <li><a href="/wiki/IEEE_1855" title="IEEE 1855">1855</a></li> <li><a href="/wiki/DySPAN" title="DySPAN">1900</a></li> <li><a href="/wiki/IEEE_1901" title="IEEE 1901">1901</a></li> <li><a href="/wiki/RuBee" title="RuBee">1902</a></li> <li><a href="/wiki/Service_Interoperability_in_Ethernet_Passive_Optical_Networks" title="Service Interoperability in Ethernet Passive Optical Networks">1904</a></li> <li><a href="/wiki/IEEE_1905" title="IEEE 1905">1905</a></li> <li><a href="/wiki/IEEE_2030" title="IEEE 2030">2030</a></li> <li><a href="/wiki/Micro_T-Kernel" title="Micro T-Kernel">2050</a></li> <li><a href="/wiki/ISO/IEEE_11073" title="ISO/IEEE 11073">11073</a></li> <li><a href="/wiki/ISO/IEC_12207" title="ISO/IEC 12207">12207</a></li> <li><a href="/wiki/Software_maintenance" title="Software maintenance">14764</a></li> <li><a href="/wiki/Risk_management" title="Risk management">16085</a></li> <li><a href="/wiki/Project_management" title="Project management">16326</a></li> <li><a href="/wiki/Requirements_engineering" title="Requirements engineering">29148</a></li> <li><a href="/wiki/ISO/IEC_42010" title="ISO/IEC 42010">42010</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/IEEE_802" title="IEEE 802">802 series</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/IEEE_802" title="IEEE 802">802</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/IEEE_802.2" title="IEEE 802.2">.2</a></li> <li><a href="/wiki/Token_bus_network" title="Token bus network">.4</a></li> <li><a href="/wiki/Token_Ring" title="Token Ring">.5</a></li> <li><a href="/wiki/IEEE_802.6" title="IEEE 802.6">.6</a></li> <li><a href="/wiki/IEEE_802.7" title="IEEE 802.7">.7</a></li> <li><a href="/wiki/IEEE_802.8" title="IEEE 802.8">.8</a></li> <li><a href="/wiki/IEEE_802.9" title="IEEE 802.9">.9</a></li> <li><a href="/wiki/IEEE_802.10" title="IEEE 802.10">.10</a></li> <li><a href="/wiki/100BaseVG" title="100BaseVG">.12</a></li> <li><a href="/wiki/Cable_modem#IEEE_802.14" title="Cable modem">.14</a></li> <li><a href="/wiki/IEEE_802.16" title="IEEE 802.16">.16</a> <ul><li><a href="/wiki/WiMAX" title="WiMAX">WiMAX · d · e</a></li></ul></li> <li><a href="/wiki/Resilient_Packet_Ring" title="Resilient Packet Ring">.17</a></li> <li><a href="/wiki/IEEE_802.18" title="IEEE 802.18">.18</a></li> <li><a href="/wiki/IEEE_802.20" title="IEEE 802.20">.20</a></li> <li><a href="/wiki/IEEE_802.21" title="IEEE 802.21">.21</a></li> <li><a href="/wiki/IEEE_802.22" title="IEEE 802.22">.22</a></li> <li><a href="/w/index.php?title=IEEE_802.24&action=edit&redlink=1" class="new" title="IEEE 802.24 (page does not exist)">.24</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/IEEE_802.1" title="IEEE 802.1">802.1</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/IEEE_802.1D" title="IEEE 802.1D">D</a></li> <li><a href="/wiki/IEEE_P802.1p" title="IEEE P802.1p">p</a></li> <li><a href="/wiki/IEEE_802.1Q" title="IEEE 802.1Q">Q</a></li> <li><a href="/wiki/IEEE_802.1Qav" class="mw-redirect" title="IEEE 802.1Qav">Qav</a></li> <li><a href="/wiki/Stream_Reservation_Protocol" title="Stream Reservation Protocol">Qat</a></li> <li><a href="/wiki/Provider_Backbone_Bridge_Traffic_Engineering" title="Provider Backbone Bridge Traffic Engineering">Qay</a></li> <li><a href="/wiki/Data_center_bridging#IEEE_Task_Group" title="Data center bridging">Qaz</a></li> <li><a href="/wiki/IEEE_802.1Qbb" class="mw-redirect" title="IEEE 802.1Qbb">Qbb</a></li> <li><a href="/wiki/Spanning_Tree_Protocol" title="Spanning Tree Protocol">w</a></li> <li><a href="/wiki/IEEE_802.1X" title="IEEE 802.1X">X</a></li> <li><a href="/wiki/Link_Layer_Discovery_Protocol" title="Link Layer Discovery Protocol">AB</a></li> <li><a href="/wiki/IEEE_802.1ad" title="IEEE 802.1ad">ad</a></li> <li><a href="/wiki/IEEE_802.1AE" title="IEEE 802.1AE">AE</a></li> <li><a href="/wiki/IEEE_802.1ag" title="IEEE 802.1ag">ag</a></li> <li><a href="/wiki/IEEE_802.1ah-2008" class="mw-redirect" title="IEEE 802.1ah-2008">ah</a></li> <li><a href="/wiki/Multiple_Registration_Protocol" title="Multiple Registration Protocol">ak</a></li> <li><a href="/wiki/IEEE_802.1aq" title="IEEE 802.1aq">aq</a></li> <li><a href="/wiki/IEEE_802.1AS" class="mw-redirect" title="IEEE 802.1AS">AS</a></li> <li><a href="/wiki/Link_aggregation" title="Link aggregation">AX</a> (<a href="/wiki/Link_Aggregation_Control_Protocol" class="mw-redirect" title="Link Aggregation Control Protocol">LACP</a>)</li> <li><a href="/wiki/Audio_Video_Bridging" title="Audio Video Bridging">BA</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/IEEE_802.3" title="IEEE 802.3">802.3</a> <br />(<a href="/wiki/Ethernet" title="Ethernet">Ethernet</a>)</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/10BASE5" title="10BASE5">-1983</a></li> <li><a href="/wiki/802.3a" class="mw-redirect" title="802.3a">a</a></li> <li><a href="/wiki/802.3b" class="mw-redirect" title="802.3b">b</a></li> <li><a href="/wiki/802.3d" class="mw-redirect" title="802.3d">d</a></li> <li><a href="/wiki/802.3e" class="mw-redirect" title="802.3e">e</a></li> <li><a href="/wiki/802.3i" class="mw-redirect" title="802.3i">i</a></li> <li><a href="/wiki/802.3j" class="mw-redirect" title="802.3j">j</a></li> <li><a href="/wiki/802.3u" class="mw-redirect" title="802.3u">u</a></li> <li><a href="/wiki/IEEE_802.3x" class="mw-redirect" title="IEEE 802.3x">x</a></li> <li><a href="/wiki/802.3y" class="mw-redirect" title="802.3y">y</a></li> <li><a href="/wiki/802.3z" class="mw-redirect" title="802.3z">z</a></li> <li><a href="/wiki/802.3ab" class="mw-redirect" title="802.3ab">ab</a></li> <li><a href="/wiki/802.3ac" class="mw-redirect" title="802.3ac">ac</a></li> <li><a href="/wiki/802.3ad" class="mw-redirect" title="802.3ad">ad</a></li> <li><a href="/wiki/802.3ae" class="mw-redirect" title="802.3ae">ae</a></li> <li><b><a href="/wiki/802.3af" class="mw-redirect" title="802.3af">af</a></b></li> <li><a href="/wiki/802.3ah" class="mw-redirect" title="802.3ah">ah</a></li> <li><a href="/wiki/802.3ak" class="mw-redirect" title="802.3ak">ak</a></li> <li><a href="/wiki/802.3an" class="mw-redirect" title="802.3an">an</a></li> <li><a href="/wiki/802.3aq" class="mw-redirect" title="802.3aq">aq</a></li> <li><b><a href="/wiki/802.3at" class="mw-redirect" title="802.3at">at</a></b></li> <li><a href="/wiki/802.3au" class="mw-redirect" title="802.3au">au</a></li> <li><a href="/wiki/802.3av" class="mw-redirect" title="802.3av">av</a></li> <li><a href="/wiki/802.3az" class="mw-redirect" title="802.3az">az</a></li> <li><a href="/wiki/802.3ba" class="mw-redirect" title="802.3ba">ba</a></li> <li><b><a href="/wiki/802.3bt" class="mw-redirect" title="802.3bt">bt</a></b></li> <li><a href="/wiki/802.3bu" class="mw-redirect" title="802.3bu">bu</a></li> <li><a href="/wiki/802.3by" class="mw-redirect" title="802.3by">by</a></li> <li><a href="/wiki/802.3bz" class="mw-redirect" title="802.3bz">bz</a></li> <li><a href="/w/index.php?title=802.3ca&action=edit&redlink=1" class="new" title="802.3ca (page does not exist)">ca</a></li> <li><a href="/w/index.php?title=802.3cb&action=edit&redlink=1" class="new" title="802.3cb (page does not exist)">cb</a></li> <li><a href="/w/index.php?title=802.3cc&action=edit&redlink=1" class="new" title="802.3cc (page does not exist)">cc</a></li> <li><a href="/w/index.php?title=802.3cd&action=edit&redlink=1" class="new" title="802.3cd (page does not exist)">cd</a></li> <li><a href="/w/index.php?title=802.3ce&action=edit&redlink=1" class="new" title="802.3ce (page does not exist)">ce</a></li> <li><a href="/wiki/802.3cg" class="mw-redirect" title="802.3cg">cg</a></li> <li><a href="/wiki/802.3ch" class="mw-redirect" title="802.3ch">ch</a></li> <li><a href="/w/index.php?title=802.3ck&action=edit&redlink=1" class="new" title="802.3ck (page does not exist)">ck</a></li> <li><a href="/w/index.php?title=802.3cm&action=edit&redlink=1" class="new" title="802.3cm (page does not exist)">cm</a></li> <li><a href="/w/index.php?title=802.3cn&action=edit&redlink=1" class="new" title="802.3cn (page does not exist)">cn</a></li> <li><a href="/w/index.php?title=802.3cp&action=edit&redlink=1" class="new" title="802.3cp (page does not exist)">cp</a></li> <li><a href="/wiki/802.3cq" class="mw-redirect" title="802.3cq">cq</a></li> <li><a href="/w/index.php?title=802.3cr&action=edit&redlink=1" class="new" title="802.3cr (page does not exist)">cr</a></li> <li><a href="/w/index.php?title=802.3cs&action=edit&redlink=1" class="new" title="802.3cs (page does not exist)">cs</a></li> <li><a href="/w/index.php?title=802.3ct&action=edit&redlink=1" class="new" title="802.3ct (page does not exist)">ct</a></li> <li><a href="/w/index.php?title=802.3cu&action=edit&redlink=1" class="new" title="802.3cu (page does not exist)">cu</a></li> <li><a href="/wiki/802.3cv" class="mw-redirect" title="802.3cv">cv</a></li> <li><a href="/w/index.php?title=802.3cw&action=edit&redlink=1" class="new" title="802.3cw (page does not exist)">cw</a></li> <li><a href="/w/index.php?title=802.3cx&action=edit&redlink=1" class="new" title="802.3cx (page does not exist)">cx</a></li> <li><a href="/w/index.php?title=802.3cy&action=edit&redlink=1" class="new" title="802.3cy (page does not exist)">cy</a></li> <li><a href="/w/index.php?title=802.3cz&action=edit&redlink=1" class="new" title="802.3cz (page does not exist)">cz</a></li> <li><a href="/w/index.php?title=802.3da&action=edit&redlink=1" class="new" title="802.3da (page does not exist)">da</a></li> <li><a href="/w/index.php?title=802.3db&action=edit&redlink=1" class="new" title="802.3db (page does not exist)">db</a></li> <li><a href="/wiki/802.3dd" class="mw-redirect" title="802.3dd">dd</a></li> <li><a href="/w/index.php?title=802.3de&action=edit&redlink=1" class="new" title="802.3de (page does not exist)">de</a></li> <li><a href="/w/index.php?title=802.3df&action=edit&redlink=1" class="new" title="802.3df (page does not exist)">df</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/IEEE_802.11" title="IEEE 802.11">802.11</a> <br />(<a href="/wiki/Wi-Fi" title="Wi-Fi">Wi-Fi</a>)</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/IEEE_802.11-1997" class="mw-redirect" title="IEEE 802.11-1997">-1997</a></li> <li><a href="/wiki/IEEE_802.11_(legacy_mode)" title="IEEE 802.11 (legacy mode)">legacy mode</a></li> <li><a href="/wiki/IEEE_802.11a-1999" title="IEEE 802.11a-1999">a</a></li> <li><a href="/wiki/IEEE_802.11b-1999" title="IEEE 802.11b-1999">b</a></li> <li><a href="/wiki/IEEE_802.11c" title="IEEE 802.11c">c</a></li> <li><a href="/wiki/IEEE_802.11d-2001" title="IEEE 802.11d-2001">d</a></li> <li><a href="/wiki/IEEE_802.11e-2005" title="IEEE 802.11e-2005">e</a></li> <li><a href="/wiki/Inter-Access_Point_Protocol" title="Inter-Access Point Protocol">f</a></li> <li><a href="/wiki/IEEE_802.11g-2003" title="IEEE 802.11g-2003">g</a></li> <li><a href="/wiki/IEEE_802.11h-2003" title="IEEE 802.11h-2003">h</a></li> <li><a href="/wiki/IEEE_802.11i-2004" title="IEEE 802.11i-2004">i</a></li> <li><a href="/wiki/IEEE_802.11j-2004" title="IEEE 802.11j-2004">j</a></li> <li><a href="/wiki/IEEE_802.11k-2008" title="IEEE 802.11k-2008">k</a></li> <li><b><a href="/wiki/IEEE_802.11n-2009" title="IEEE 802.11n-2009">n</a></b> (<a href="/wiki/Wi-Fi_4" class="mw-redirect" title="Wi-Fi 4">Wi-Fi 4</a>)</li> <li><a href="/wiki/IEEE_802.11p" title="IEEE 802.11p">p</a></li> <li><a href="/wiki/IEEE_802.11r-2008" title="IEEE 802.11r-2008">r</a></li> <li><a href="/wiki/IEEE_802.11s" title="IEEE 802.11s">s</a></li> <li><a href="/wiki/IEEE_802.11u" title="IEEE 802.11u">u</a></li> <li><a href="/wiki/IEEE_802.11v" class="mw-redirect" title="IEEE 802.11v">v</a></li> <li><a href="/wiki/IEEE_802.11w-2009" title="IEEE 802.11w-2009">w</a></li> <li><a href="/wiki/IEEE_802.11y-2008" title="IEEE 802.11y-2008">y</a></li> <li><a href="/wiki/IEEE_802.11z" class="mw-redirect" title="IEEE 802.11z">z</a></li> <li>aa</li> <li><b><a href="/wiki/IEEE_802.11ac" class="mw-redirect" title="IEEE 802.11ac">ac</a></b> (<a href="/wiki/Wi-Fi_5" class="mw-redirect" title="Wi-Fi 5">Wi-Fi 5</a>)</li> <li><a href="/wiki/IEEE_802.11ad" title="IEEE 802.11ad">ad</a> (<a href="/wiki/WiGig" title="WiGig">WiGig</a>)</li> <li>ae</li> <li><a href="/wiki/IEEE_802.11af" title="IEEE 802.11af">af</a></li> <li><a href="/wiki/IEEE_802.11ah" title="IEEE 802.11ah">ah</a></li> <li><a href="/wiki/IEEE_802.11ai" title="IEEE 802.11ai">ai</a></li> <li><a href="/wiki/IEEE_802.11aj" class="mw-redirect" title="IEEE 802.11aj">aj</a></li> <li>ak</li> <li>aq</li> <li><b><a href="/wiki/IEEE_802.11ax" class="mw-redirect" title="IEEE 802.11ax">ax</a></b> (<a href="/wiki/Wi-Fi_6" title="Wi-Fi 6">Wi-Fi 6</a>)</li> <li><a href="/wiki/IEEE_802.11ay" title="IEEE 802.11ay">ay</a></li> <li>az</li> <li>ba</li> <li><a href="/wiki/IEEE_802.11bb" title="IEEE 802.11bb">bb</a></li> <li>bc</li> <li>bd</li> <li><b><a href="/wiki/IEEE_802.11be" class="mw-redirect" title="IEEE 802.11be">be</a></b> (<a href="/wiki/Wi-Fi_7" title="Wi-Fi 7">Wi-Fi 7</a>)</li> <li>bf</li> <li>bh</li> <li>bi</li> <li>bk</li> <li><b><a href="/wiki/IEEE_802.11bn" title="IEEE 802.11bn">bn</a></b> (<a href="/w/index.php?title=Wi-Fi_8&action=edit&redlink=1" class="new" title="Wi-Fi 8 (page does not exist)">Wi-Fi 8</a>)</li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/IEEE_802.15" title="IEEE 802.15">802.15</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/IEEE_802.15.1" class="mw-redirect" title="IEEE 802.15.1">.1</a> (<a href="/wiki/Bluetooth" title="Bluetooth">Bluetooth</a>)</li> <li><a href="/wiki/IEEE_802.15.2" class="mw-redirect" title="IEEE 802.15.2">.2</a></li> <li><a href="/wiki/IEEE_802.15.3" class="mw-redirect" title="IEEE 802.15.3">.3</a></li> <li><a href="/wiki/IEEE_802.15.4" title="IEEE 802.15.4">.4</a> (<a href="/wiki/Zigbee" title="Zigbee">Zigbee</a>)</li> <li><a href="/wiki/IEEE_802.15.4a" title="IEEE 802.15.4a">.4a</a></li> <li><a href="/w/index.php?title=IEEE_802.15.4b&action=edit&redlink=1" class="new" title="IEEE 802.15.4b (page does not exist)">.4b</a></li> <li><a href="/w/index.php?title=IEEE_802.15.4c&action=edit&redlink=1" class="new" title="IEEE 802.15.4c (page does not exist)">.4c</a></li> <li><a href="/w/index.php?title=IEEE_802.15.4d&action=edit&redlink=1" class="new" title="IEEE 802.15.4d (page does not exist)">.4d</a></li> <li><a href="/w/index.php?title=IEEE_802.15.4e&action=edit&redlink=1" class="new" title="IEEE 802.15.4e (page does not exist)">.4e</a></li> <li><a href="/w/index.php?title=IEEE_802.15.4f&action=edit&redlink=1" class="new" title="IEEE 802.15.4f (page does not exist)">.4f</a></li> <li><a href="/w/index.php?title=IEEE_802.15.4g&action=edit&redlink=1" class="new" title="IEEE 802.15.4g (page does not exist)">.4g</a></li> <li><a href="/w/index.php?title=IEEE_802.15.4z&action=edit&redlink=1" class="new" title="IEEE 802.15.4z (page does not exist)">.4z</a></li> <li><a href="/wiki/IEEE_802.15.5" class="mw-redirect" title="IEEE 802.15.5">.5</a></li> <li><a href="/wiki/IEEE_802.15.6" title="IEEE 802.15.6">.6</a></li> <li><a href="/wiki/IEEE_802.15.7" class="mw-redirect" title="IEEE 802.15.7">.7</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Proposed</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/IEEE_P1363" title="IEEE P1363">P1363</a></li> <li><a href="/wiki/IEEE_P1619" title="IEEE P1619">P1619</a></li> <li><a href="/wiki/Rosetta-lang" title="Rosetta-lang">P1699</a></li> <li><a href="/wiki/Universal_Power_Adapter_for_Mobile_Devices" title="Universal Power Adapter for Mobile Devices">P1823</a></li> <li><a href="/wiki/IEEE_P1906.1" title="IEEE P1906.1">P1906.1</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Superseded</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/IEEE_754-1985" title="IEEE 754-1985">754-1985</a></li> <li><a href="/wiki/Software_requirements_specification" title="Software requirements specification">830</a></li> <li><a href="/wiki/IEEE_1219" class="mw-redirect" title="IEEE 1219">1219</a></li> <li><a href="/wiki/Software_requirements_specification" title="Software requirements specification">1233</a></li> <li><a href="/wiki/Concept_of_operations" title="Concept of operations">1362</a></li> <li><a href="/wiki/Verilog" title="Verilog">1364</a></li> <li><a href="/wiki/IEEE_1471" title="IEEE 1471">1471</a></li></ul> </div></td></tr><tr><td class="navbox-abovebelow" colspan="2"><div> <dl><dt><i>See also</i></dt> <dd><a href="/wiki/IEEE_Standards_Association" title="IEEE Standards Association">IEEE Standards Association</a></dd> <dd><a href="/wiki/Category:IEEE_standards" title="Category:IEEE standards">Category:IEEE standards</a></dd></dl> </div></td></tr></tbody></table></div>    </div><noscript><img src="https://login.wikimedia.org/wiki/Special:CentralAutoLogin/start?type=1x1" alt="" width="1" height="1" style="border: none; position: absolute;"></noscript> <div class="printfooter" data-nosnippet="">Retrieved from "<a dir="ltr" href="https://en.wikipedia.org/w/index.php?title=Precision_Time_Protocol&oldid=1247519903">https://en.wikipedia.org/w/index.php?title=Precision_Time_Protocol&oldid=1247519903</a>"</div></div> <div id="catlinks" class="catlinks" data-mw="interface"><div id="mw-normal-catlinks" class="mw-normal-catlinks"><a href="/wiki/Help:Category" title="Help:Category">Categories</a>: <ul><li><a href="/wiki/Category:Synchronization" title="Category:Synchronization">Synchronization</a></li><li><a href="/wiki/Category:IEEE_standards" title="Category:IEEE standards">IEEE standards</a></li><li><a href="/wiki/Category:Network_time-related_software" title="Category:Network time-related software">Network time-related software</a></li><li><a href="/wiki/Category:Network_protocols" title="Category:Network protocols">Network protocols</a></li><li><a href="/wiki/Category:Application_layer_protocols" title="Category:Application layer protocols">Application layer protocols</a></li></ul></div><div id="mw-hidden-catlinks" class="mw-hidden-catlinks mw-hidden-cats-hidden">Hidden categories: <ul><li><a href="/wiki/Category:All_articles_with_dead_external_links" title="Category:All articles with dead external links">All articles with dead external links</a></li><li><a href="/wiki/Category:Articles_with_dead_external_links_from_February_2022" title="Category:Articles with dead external links from February 2022">Articles with dead external links from February 2022</a></li><li><a href="/wiki/Category:Articles_with_short_description" title="Category:Articles with short description">Articles with short description</a></li><li><a href="/wiki/Category:Short_description_matches_Wikidata" title="Category:Short description matches Wikidata">Short description matches Wikidata</a></li><li><a href="/wiki/Category:Use_American_English_from_April_2020" title="Category:Use American English from April 2020">Use American English from April 2020</a></li><li><a href="/wiki/Category:All_Wikipedia_articles_written_in_American_English" title="Category:All Wikipedia articles written in American English">All Wikipedia articles written in American English</a></li><li><a href="/wiki/Category:Use_dmy_dates_from_June_2020" title="Category:Use dmy dates from June 2020">Use dmy dates from June 2020</a></li><li><a href="/wiki/Category:All_articles_with_unsourced_statements" title="Category:All articles with unsourced statements">All articles with unsourced statements</a></li><li><a href="/wiki/Category:Articles_with_unsourced_statements_from_September_2024" title="Category:Articles with unsourced statements from September 2024">Articles with unsourced statements from September 2024</a></li></ul></div></div> </div> </main> </div> <div class="mw-footer-container"> <footer id="footer" class="mw-footer" > <ul id="footer-info"> <li id="footer-info-lastmod"> This page was last edited on 24 September 2024, at 17:20<span class="anonymous-show"> (UTC)</span>.</li> <li id="footer-info-copyright">Text is available under the <a href="/wiki/Wikipedia:Text_of_the_Creative_Commons_Attribution-ShareAlike_4.0_International_License" title="Wikipedia:Text of the Creative Commons Attribution-ShareAlike 4.0 International License">Creative Commons Attribution-ShareAlike 4.0 License</a>; additional terms may apply. By using this site, you agree to the <a href="https://foundation.wikimedia.org/wiki/Special:MyLanguage/Policy:Terms_of_Use" class="extiw" title="foundation:Special:MyLanguage/Policy:Terms of Use">Terms of Use</a> and <a href="https://foundation.wikimedia.org/wiki/Special:MyLanguage/Policy:Privacy_policy" class="extiw" title="foundation:Special:MyLanguage/Policy:Privacy policy">Privacy Policy</a>. Wikipedia® is a registered trademark of the <a rel="nofollow" class="external text" href="https://wikimediafoundation.org/">Wikimedia Foundation, Inc.</a>, a non-profit organization.</li> </ul> <ul id="footer-places"> <li id="footer-places-privacy"><a href="https://foundation.wikimedia.org/wiki/Special:MyLanguage/Policy:Privacy_policy">Privacy policy</a></li> <li id="footer-places-about"><a href="/wiki/Wikipedia:About">About Wikipedia</a></li> <li id="footer-places-disclaimers"><a href="/wiki/Wikipedia:General_disclaimer">Disclaimers</a></li> <li id="footer-places-contact"><a href="//en.wikipedia.org/wiki/Wikipedia:Contact_us">Contact Wikipedia</a></li> <li id="footer-places-wm-codeofconduct"><a href="https://foundation.wikimedia.org/wiki/Special:MyLanguage/Policy:Universal_Code_of_Conduct">Code of Conduct</a></li> <li id="footer-places-developers"><a href="https://developer.wikimedia.org">Developers</a></li> <li id="footer-places-statslink"><a href="https://stats.wikimedia.org/#/en.wikipedia.org">Statistics</a></li> <li id="footer-places-cookiestatement"><a href="https://foundation.wikimedia.org/wiki/Special:MyLanguage/Policy:Cookie_statement">Cookie statement</a></li> <li id="footer-places-mobileview"><a href="//en.m.wikipedia.org/w/index.php?title=Precision_Time_Protocol&mobileaction=toggle_view_mobile" class="noprint stopMobileRedirectToggle">Mobile view</a></li> </ul> <ul id="footer-icons" class="noprint"> <li id="footer-copyrightico"><a href="https://wikimediafoundation.org/" class="cdx-button cdx-button--fake-button cdx-button--size-large cdx-button--fake-button--enabled"><img src="/static/images/footer/wikimedia-button.svg" width="84" height="29" alt="Wikimedia Foundation" loading="lazy"></a></li> <li id="footer-poweredbyico"><a href="https://www.mediawiki.org/" class="cdx-button cdx-button--fake-button cdx-button--size-large cdx-button--fake-button--enabled"><img src="/w/resources/assets/poweredby_mediawiki.svg" alt="Powered by MediaWiki" width="88" height="31" loading="lazy"></a></li> </ul> </footer> </div> </div> </div> <div class="vector-settings" id="p-dock-bottom"> <ul></ul> </div><script>(RLQ=window.RLQ||[]).push(function(){mw.config.set({"wgHostname":"mw-web.codfw.main-6df7948d6c-kr5z4","wgBackendResponseTime":162,"wgPageParseReport":{"limitreport":{"cputime":"0.551","walltime":"0.741","ppvisitednodes":{"value":6467,"limit":1000000},"postexpandincludesize":{"value":88330,"limit":2097152},"templateargumentsize":{"value":6213,"limit":2097152},"expansiondepth":{"value":20,"limit":100},"expensivefunctioncount":{"value":5,"limit":500},"unstrip-depth":{"value":1,"limit":20},"unstrip-size":{"value":81270,"limit":5000000},"entityaccesscount":{"value":0,"limit":400},"timingprofile":["100.00% 552.667 1 -total"," 27.94% 154.403 2 Template:Reflist"," 16.47% 91.038 2 Template:Annotated_link"," 16.04% 88.664 7 Template:Cite_web"," 13.89% 76.769 15 Template:Rp"," 13.00% 71.871 1 Template:IEEE_standards"," 12.85% 71.043 15 Template:R/superscript"," 12.69% 70.129 2 Template:Navbox"," 10.22% 56.486 1 Template:Short_description"," 6.52% 36.032 2 Template:Pagetype"]},"scribunto":{"limitreport-timeusage":{"value":"0.298","limit":"10.000"},"limitreport-memusage":{"value":19733107,"limit":52428800}},"cachereport":{"origin":"mw-web.codfw.main-6df7948d6c-djcv5","timestamp":"20241127201625","ttl":2592000,"transientcontent":false}}});});</script> <script type="application/ld+json">{"@context":"https:\/\/schema.org","@type":"Article","name":"Precision Time Protocol","url":"https:\/\/en.wikipedia.org\/wiki\/Precision_Time_Protocol","sameAs":"http:\/\/www.wikidata.org\/entity\/Q1143243","mainEntity":"http:\/\/www.wikidata.org\/entity\/Q1143243","author":{"@type":"Organization","name":"Contributors to Wikimedia projects"},"publisher":{"@type":"Organization","name":"Wikimedia Foundation, Inc.","logo":{"@type":"ImageObject","url":"https:\/\/www.wikimedia.org\/static\/images\/wmf-hor-googpub.png"}},"datePublished":"2005-06-30T07:57:02Z","dateModified":"2024-09-24T17:20:45Z","headline":"network time synchronization protocol"}</script> </body> </html>