SHA256
1
0
AnnNet/README.html
2025-08-28 07:47:33 -04:00

2878 lines
149 KiB
HTML

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta name="generator" content="Asciidoctor 2.0.23">
<meta name="author" content="Brent Saner">
<title>AnnNet Specification</title>
<link rel="stylesheet" href="https://fonts.googleapis.com/css?family=Open+Sans:300,300italic,400,400italic,600,600italic%7CNoto+Serif:400,400italic,700,700italic%7CDroid+Sans+Mono:400,700">
<style>
/*! Asciidoctor default stylesheet | MIT License | https://asciidoctor.org */
/* Uncomment the following line when using as a custom stylesheet */
/* @import "https://fonts.googleapis.com/css?family=Open+Sans:300,300italic,400,400italic,600,600italic%7CNoto+Serif:400,400italic,700,700italic%7CDroid+Sans+Mono:400,700"; */
html{font-family:sans-serif;-webkit-text-size-adjust:100%}
a{background:none}
a:focus{outline:thin dotted}
a:active,a:hover{outline:0}
h1{font-size:2em;margin:.67em 0}
b,strong{font-weight:bold}
abbr{font-size:.9em}
abbr[title]{cursor:help;border-bottom:1px dotted #dddddf;text-decoration:none}
dfn{font-style:italic}
hr{height:0}
mark{background:#ff0;color:#000}
code,kbd,pre,samp{font-family:monospace;font-size:1em}
pre{white-space:pre-wrap}
q{quotes:"\201C" "\201D" "\2018" "\2019"}
small{font-size:80%}
sub,sup{font-size:75%;line-height:0;position:relative;vertical-align:baseline}
sup{top:-.5em}
sub{bottom:-.25em}
img{border:0}
svg:not(:root){overflow:hidden}
figure{margin:0}
audio,video{display:inline-block}
audio:not([controls]){display:none;height:0}
fieldset{border:1px solid silver;margin:0 2px;padding:.35em .625em .75em}
legend{border:0;padding:0}
button,input,select,textarea{font-family:inherit;font-size:100%;margin:0}
button,input{line-height:normal}
button,select{text-transform:none}
button,html input[type=button],input[type=reset],input[type=submit]{-webkit-appearance:button;cursor:pointer}
button[disabled],html input[disabled]{cursor:default}
input[type=checkbox],input[type=radio]{padding:0}
button::-moz-focus-inner,input::-moz-focus-inner{border:0;padding:0}
textarea{overflow:auto;vertical-align:top}
table{border-collapse:collapse;border-spacing:0}
*,::before,::after{box-sizing:border-box}
html,body{font-size:100%}
body{background:#fff;color:rgba(0,0,0,.8);padding:0;margin:0;font-family:"Noto Serif","DejaVu Serif",serif;line-height:1;position:relative;cursor:auto;-moz-tab-size:4;-o-tab-size:4;tab-size:4;word-wrap:anywhere;-moz-osx-font-smoothing:grayscale;-webkit-font-smoothing:antialiased}
a:hover{cursor:pointer}
img,object,embed{max-width:100%;height:auto}
object,embed{height:100%}
img{-ms-interpolation-mode:bicubic}
.left{float:left!important}
.right{float:right!important}
.text-left{text-align:left!important}
.text-right{text-align:right!important}
.text-center{text-align:center!important}
.text-justify{text-align:justify!important}
.hide{display:none}
img,object,svg{display:inline-block;vertical-align:middle}
textarea{height:auto;min-height:50px}
select{width:100%}
.subheader,.admonitionblock td.content>.title,.audioblock>.title,.exampleblock>.title,.imageblock>.title,.listingblock>.title,.literalblock>.title,.stemblock>.title,.openblock>.title,.paragraph>.title,.quoteblock>.title,table.tableblock>.title,.verseblock>.title,.videoblock>.title,.dlist>.title,.olist>.title,.ulist>.title,.qlist>.title,.hdlist>.title{line-height:1.45;color:#7a2518;font-weight:400;margin-top:0;margin-bottom:.25em}
div,dl,dt,dd,ul,ol,li,h1,h2,h3,#toctitle,.sidebarblock>.content>.title,h4,h5,h6,pre,form,p,blockquote,th,td{margin:0;padding:0}
a{color:#2156a5;text-decoration:underline;line-height:inherit}
a:hover,a:focus{color:#1d4b8f}
a img{border:0}
p{line-height:1.6;margin-bottom:1.25em;text-rendering:optimizeLegibility}
p aside{font-size:.875em;line-height:1.35;font-style:italic}
h1,h2,h3,#toctitle,.sidebarblock>.content>.title,h4,h5,h6{font-family:"Open Sans","DejaVu Sans",sans-serif;font-weight:300;font-style:normal;color:#ba3925;text-rendering:optimizeLegibility;margin-top:1em;margin-bottom:.5em;line-height:1.0125em}
h1 small,h2 small,h3 small,#toctitle small,.sidebarblock>.content>.title small,h4 small,h5 small,h6 small{font-size:60%;color:#e99b8f;line-height:0}
h1{font-size:2.125em}
h2{font-size:1.6875em}
h3,#toctitle,.sidebarblock>.content>.title{font-size:1.375em}
h4,h5{font-size:1.125em}
h6{font-size:1em}
hr{border:solid #dddddf;border-width:1px 0 0;clear:both;margin:1.25em 0 1.1875em}
em,i{font-style:italic;line-height:inherit}
strong,b{font-weight:bold;line-height:inherit}
small{font-size:60%;line-height:inherit}
code{font-family:"Droid Sans Mono","DejaVu Sans Mono",monospace;font-weight:400;color:rgba(0,0,0,.9)}
ul,ol,dl{line-height:1.6;margin-bottom:1.25em;list-style-position:outside;font-family:inherit}
ul,ol{margin-left:1.5em}
ul li ul,ul li ol{margin-left:1.25em;margin-bottom:0}
ul.circle{list-style-type:circle}
ul.disc{list-style-type:disc}
ul.square{list-style-type:square}
ul.circle ul:not([class]),ul.disc ul:not([class]),ul.square ul:not([class]){list-style:inherit}
ol li ul,ol li ol{margin-left:1.25em;margin-bottom:0}
dl dt{margin-bottom:.3125em;font-weight:bold}
dl dd{margin-bottom:1.25em}
blockquote{margin:0 0 1.25em;padding:.5625em 1.25em 0 1.1875em;border-left:1px solid #ddd}
blockquote,blockquote p{line-height:1.6;color:rgba(0,0,0,.85)}
@media screen and (min-width:768px){h1,h2,h3,#toctitle,.sidebarblock>.content>.title,h4,h5,h6{line-height:1.2}
h1{font-size:2.75em}
h2{font-size:2.3125em}
h3,#toctitle,.sidebarblock>.content>.title{font-size:1.6875em}
h4{font-size:1.4375em}}
table{background:#fff;margin-bottom:1.25em;border:1px solid #dedede;word-wrap:normal}
table thead,table tfoot{background:#f7f8f7}
table thead tr th,table thead tr td,table tfoot tr th,table tfoot tr td{padding:.5em .625em .625em;font-size:inherit;color:rgba(0,0,0,.8);text-align:left}
table tr th,table tr td{padding:.5625em .625em;font-size:inherit;color:rgba(0,0,0,.8)}
table tr.even,table tr.alt{background:#f8f8f7}
table thead tr th,table tfoot tr th,table tbody tr td,table tr td,table tfoot tr td{line-height:1.6}
h1,h2,h3,#toctitle,.sidebarblock>.content>.title,h4,h5,h6{line-height:1.2;word-spacing:-.05em}
h1 strong,h2 strong,h3 strong,#toctitle strong,.sidebarblock>.content>.title strong,h4 strong,h5 strong,h6 strong{font-weight:400}
.center{margin-left:auto;margin-right:auto}
.stretch{width:100%}
.clearfix::before,.clearfix::after,.float-group::before,.float-group::after{content:" ";display:table}
.clearfix::after,.float-group::after{clear:both}
:not(pre).nobreak{word-wrap:normal}
:not(pre).nowrap{white-space:nowrap}
:not(pre).pre-wrap{white-space:pre-wrap}
:not(pre):not([class^=L])>code{font-size:.9375em;font-style:normal!important;letter-spacing:0;padding:.1em .5ex;word-spacing:-.15em;background:#f7f7f8;border-radius:4px;line-height:1.45;text-rendering:optimizeSpeed}
pre{color:rgba(0,0,0,.9);font-family:"Droid Sans Mono","DejaVu Sans Mono",monospace;line-height:1.45;text-rendering:optimizeSpeed}
pre code,pre pre{color:inherit;font-size:inherit;line-height:inherit}
pre>code{display:block}
pre.nowrap,pre.nowrap pre{white-space:pre;word-wrap:normal}
em em{font-style:normal}
strong strong{font-weight:400}
.keyseq{color:rgba(51,51,51,.8)}
kbd{font-family:"Droid Sans Mono","DejaVu Sans Mono",monospace;display:inline-block;color:rgba(0,0,0,.8);font-size:.65em;line-height:1.45;background:#f7f7f7;border:1px solid #ccc;border-radius:3px;box-shadow:0 1px 0 rgba(0,0,0,.2),inset 0 0 0 .1em #fff;margin:0 .15em;padding:.2em .5em;vertical-align:middle;position:relative;top:-.1em;white-space:nowrap}
.keyseq kbd:first-child{margin-left:0}
.keyseq kbd:last-child{margin-right:0}
.menuseq,.menuref{color:#000}
.menuseq b:not(.caret),.menuref{font-weight:inherit}
.menuseq{word-spacing:-.02em}
.menuseq b.caret{font-size:1.25em;line-height:.8}
.menuseq i.caret{font-weight:bold;text-align:center;width:.45em}
b.button::before,b.button::after{position:relative;top:-1px;font-weight:400}
b.button::before{content:"[";padding:0 3px 0 2px}
b.button::after{content:"]";padding:0 2px 0 3px}
p a>code:hover{color:rgba(0,0,0,.9)}
#header,#content,#footnotes,#footer{width:100%;margin:0 auto;max-width:62.5em;*zoom:1;position:relative;padding-left:.9375em;padding-right:.9375em}
#header::before,#header::after,#content::before,#content::after,#footnotes::before,#footnotes::after,#footer::before,#footer::after{content:" ";display:table}
#header::after,#content::after,#footnotes::after,#footer::after{clear:both}
#content{margin-top:1.25em}
#content::before{content:none}
#header>h1:first-child{color:rgba(0,0,0,.85);margin-top:2.25rem;margin-bottom:0}
#header>h1:first-child+#toc{margin-top:8px;border-top:1px solid #dddddf}
#header>h1:only-child{border-bottom:1px solid #dddddf;padding-bottom:8px}
#header .details{border-bottom:1px solid #dddddf;line-height:1.45;padding-top:.25em;padding-bottom:.25em;padding-left:.25em;color:rgba(0,0,0,.6);display:flex;flex-flow:row wrap}
#header .details span:first-child{margin-left:-.125em}
#header .details span.email a{color:rgba(0,0,0,.85)}
#header .details br{display:none}
#header .details br+span::before{content:"\00a0\2013\00a0"}
#header .details br+span.author::before{content:"\00a0\22c5\00a0";color:rgba(0,0,0,.85)}
#header .details br+span#revremark::before{content:"\00a0|\00a0"}
#header #revnumber{text-transform:capitalize}
#header #revnumber::after{content:"\00a0"}
#content>h1:first-child:not([class]){color:rgba(0,0,0,.85);border-bottom:1px solid #dddddf;padding-bottom:8px;margin-top:0;padding-top:1rem;margin-bottom:1.25rem}
#toc{border-bottom:1px solid #e7e7e9;padding-bottom:.5em}
#toc>ul{margin-left:.125em}
#toc ul.sectlevel0>li>a{font-style:italic}
#toc ul.sectlevel0 ul.sectlevel1{margin:.5em 0}
#toc ul{font-family:"Open Sans","DejaVu Sans",sans-serif;list-style-type:none}
#toc li{line-height:1.3334;margin-top:.3334em}
#toc a{text-decoration:none}
#toc a:active{text-decoration:underline}
#toctitle{color:#7a2518;font-size:1.2em}
@media screen and (min-width:768px){#toctitle{font-size:1.375em}
body.toc2{padding-left:15em;padding-right:0}
body.toc2 #header>h1:nth-last-child(2){border-bottom:1px solid #dddddf;padding-bottom:8px}
#toc.toc2{margin-top:0!important;background:#f8f8f7;position:fixed;width:15em;left:0;top:0;border-right:1px solid #e7e7e9;border-top-width:0!important;border-bottom-width:0!important;z-index:1000;padding:1.25em 1em;height:100%;overflow:auto}
#toc.toc2 #toctitle{margin-top:0;margin-bottom:.8rem;font-size:1.2em}
#toc.toc2>ul{font-size:.9em;margin-bottom:0}
#toc.toc2 ul ul{margin-left:0;padding-left:1em}
#toc.toc2 ul.sectlevel0 ul.sectlevel1{padding-left:0;margin-top:.5em;margin-bottom:.5em}
body.toc2.toc-right{padding-left:0;padding-right:15em}
body.toc2.toc-right #toc.toc2{border-right-width:0;border-left:1px solid #e7e7e9;left:auto;right:0}}
@media screen and (min-width:1280px){body.toc2{padding-left:20em;padding-right:0}
#toc.toc2{width:20em}
#toc.toc2 #toctitle{font-size:1.375em}
#toc.toc2>ul{font-size:.95em}
#toc.toc2 ul ul{padding-left:1.25em}
body.toc2.toc-right{padding-left:0;padding-right:20em}}
#content #toc{border:1px solid #e0e0dc;margin-bottom:1.25em;padding:1.25em;background:#f8f8f7;border-radius:4px}
#content #toc>:first-child{margin-top:0}
#content #toc>:last-child{margin-bottom:0}
#footer{max-width:none;background:rgba(0,0,0,.8);padding:1.25em}
#footer-text{color:hsla(0,0%,100%,.8);line-height:1.44}
#content{margin-bottom:.625em}
.sect1{padding-bottom:.625em}
@media screen and (min-width:768px){#content{margin-bottom:1.25em}
.sect1{padding-bottom:1.25em}}
.sect1:last-child{padding-bottom:0}
.sect1+.sect1{border-top:1px solid #e7e7e9}
#content h1>a.anchor,h2>a.anchor,h3>a.anchor,#toctitle>a.anchor,.sidebarblock>.content>.title>a.anchor,h4>a.anchor,h5>a.anchor,h6>a.anchor{position:absolute;z-index:1001;width:1.5ex;margin-left:-1.5ex;display:block;text-decoration:none!important;visibility:hidden;text-align:center;font-weight:400}
#content h1>a.anchor::before,h2>a.anchor::before,h3>a.anchor::before,#toctitle>a.anchor::before,.sidebarblock>.content>.title>a.anchor::before,h4>a.anchor::before,h5>a.anchor::before,h6>a.anchor::before{content:"\00A7";font-size:.85em;display:block;padding-top:.1em}
#content h1:hover>a.anchor,#content h1>a.anchor:hover,h2:hover>a.anchor,h2>a.anchor:hover,h3:hover>a.anchor,#toctitle:hover>a.anchor,.sidebarblock>.content>.title:hover>a.anchor,h3>a.anchor:hover,#toctitle>a.anchor:hover,.sidebarblock>.content>.title>a.anchor:hover,h4:hover>a.anchor,h4>a.anchor:hover,h5:hover>a.anchor,h5>a.anchor:hover,h6:hover>a.anchor,h6>a.anchor:hover{visibility:visible}
#content h1>a.link,h2>a.link,h3>a.link,#toctitle>a.link,.sidebarblock>.content>.title>a.link,h4>a.link,h5>a.link,h6>a.link{color:#ba3925;text-decoration:none}
#content h1>a.link:hover,h2>a.link:hover,h3>a.link:hover,#toctitle>a.link:hover,.sidebarblock>.content>.title>a.link:hover,h4>a.link:hover,h5>a.link:hover,h6>a.link:hover{color:#a53221}
details,.audioblock,.imageblock,.literalblock,.listingblock,.stemblock,.videoblock{margin-bottom:1.25em}
details{margin-left:1.25rem}
details>summary{cursor:pointer;display:block;position:relative;line-height:1.6;margin-bottom:.625rem;outline:none;-webkit-tap-highlight-color:transparent}
details>summary::-webkit-details-marker{display:none}
details>summary::before{content:"";border:solid transparent;border-left:solid;border-width:.3em 0 .3em .5em;position:absolute;top:.5em;left:-1.25rem;transform:translateX(15%)}
details[open]>summary::before{border:solid transparent;border-top:solid;border-width:.5em .3em 0;transform:translateY(15%)}
details>summary::after{content:"";width:1.25rem;height:1em;position:absolute;top:.3em;left:-1.25rem}
.admonitionblock td.content>.title,.audioblock>.title,.exampleblock>.title,.imageblock>.title,.listingblock>.title,.literalblock>.title,.stemblock>.title,.openblock>.title,.paragraph>.title,.quoteblock>.title,table.tableblock>.title,.verseblock>.title,.videoblock>.title,.dlist>.title,.olist>.title,.ulist>.title,.qlist>.title,.hdlist>.title{text-rendering:optimizeLegibility;text-align:left;font-family:"Noto Serif","DejaVu Serif",serif;font-size:1rem;font-style:italic}
table.tableblock.fit-content>caption.title{white-space:nowrap;width:0}
.paragraph.lead>p,#preamble>.sectionbody>[class=paragraph]:first-of-type p{font-size:1.21875em;line-height:1.6;color:rgba(0,0,0,.85)}
.admonitionblock>table{border-collapse:separate;border:0;background:none;width:100%}
.admonitionblock>table td.icon{text-align:center;width:80px}
.admonitionblock>table td.icon img{max-width:none}
.admonitionblock>table td.icon .title{font-weight:bold;font-family:"Open Sans","DejaVu Sans",sans-serif;text-transform:uppercase}
.admonitionblock>table td.content{padding-left:1.125em;padding-right:1.25em;border-left:1px solid #dddddf;color:rgba(0,0,0,.6);word-wrap:anywhere}
.admonitionblock>table td.content>:last-child>:last-child{margin-bottom:0}
.exampleblock>.content{border:1px solid #e6e6e6;margin-bottom:1.25em;padding:1.25em;background:#fff;border-radius:4px}
.sidebarblock{border:1px solid #dbdbd6;margin-bottom:1.25em;padding:1.25em;background:#f3f3f2;border-radius:4px}
.sidebarblock>.content>.title{color:#7a2518;margin-top:0;text-align:center}
.exampleblock>.content>:first-child,.sidebarblock>.content>:first-child{margin-top:0}
.exampleblock>.content>:last-child,.exampleblock>.content>:last-child>:last-child,.exampleblock>.content .olist>ol>li:last-child>:last-child,.exampleblock>.content .ulist>ul>li:last-child>:last-child,.exampleblock>.content .qlist>ol>li:last-child>:last-child,.sidebarblock>.content>:last-child,.sidebarblock>.content>:last-child>:last-child,.sidebarblock>.content .olist>ol>li:last-child>:last-child,.sidebarblock>.content .ulist>ul>li:last-child>:last-child,.sidebarblock>.content .qlist>ol>li:last-child>:last-child{margin-bottom:0}
.literalblock pre,.listingblock>.content>pre{border-radius:4px;overflow-x:auto;padding:1em;font-size:.8125em}
@media screen and (min-width:768px){.literalblock pre,.listingblock>.content>pre{font-size:.90625em}}
@media screen and (min-width:1280px){.literalblock pre,.listingblock>.content>pre{font-size:1em}}
.literalblock pre,.listingblock>.content>pre:not(.highlight),.listingblock>.content>pre[class=highlight],.listingblock>.content>pre[class^="highlight "]{background:#f7f7f8}
.literalblock.output pre{color:#f7f7f8;background:rgba(0,0,0,.9)}
.listingblock>.content{position:relative}
.listingblock code[data-lang]::before{display:none;content:attr(data-lang);position:absolute;font-size:.75em;top:.425rem;right:.5rem;line-height:1;text-transform:uppercase;color:inherit;opacity:.5}
.listingblock:hover code[data-lang]::before{display:block}
.listingblock.terminal pre .command::before{content:attr(data-prompt);padding-right:.5em;color:inherit;opacity:.5}
.listingblock.terminal pre .command:not([data-prompt])::before{content:"$"}
.listingblock pre.highlightjs{padding:0}
.listingblock pre.highlightjs>code{padding:1em;border-radius:4px}
.listingblock pre.prettyprint{border-width:0}
.prettyprint{background:#f7f7f8}
pre.prettyprint .linenums{line-height:1.45;margin-left:2em}
pre.prettyprint li{background:none;list-style-type:inherit;padding-left:0}
pre.prettyprint li code[data-lang]::before{opacity:1}
pre.prettyprint li:not(:first-child) code[data-lang]::before{display:none}
table.linenotable{border-collapse:separate;border:0;margin-bottom:0;background:none}
table.linenotable td[class]{color:inherit;vertical-align:top;padding:0;line-height:inherit;white-space:normal}
table.linenotable td.code{padding-left:.75em}
table.linenotable td.linenos,pre.pygments .linenos{border-right:1px solid;opacity:.35;padding-right:.5em;-webkit-user-select:none;-moz-user-select:none;-ms-user-select:none;user-select:none}
pre.pygments span.linenos{display:inline-block;margin-right:.75em}
.quoteblock{margin:0 1em 1.25em 1.5em;display:table}
.quoteblock:not(.excerpt)>.title{margin-left:-1.5em;margin-bottom:.75em}
.quoteblock blockquote,.quoteblock p{color:rgba(0,0,0,.85);font-size:1.15rem;line-height:1.75;word-spacing:.1em;letter-spacing:0;font-style:italic;text-align:justify}
.quoteblock blockquote{margin:0;padding:0;border:0}
.quoteblock blockquote::before{content:"\201c";float:left;font-size:2.75em;font-weight:bold;line-height:.6em;margin-left:-.6em;color:#7a2518;text-shadow:0 1px 2px rgba(0,0,0,.1)}
.quoteblock blockquote>.paragraph:last-child p{margin-bottom:0}
.quoteblock .attribution{margin-top:.75em;margin-right:.5ex;text-align:right}
.verseblock{margin:0 1em 1.25em}
.verseblock pre{font-family:"Open Sans","DejaVu Sans",sans-serif;font-size:1.15rem;color:rgba(0,0,0,.85);font-weight:300;text-rendering:optimizeLegibility}
.verseblock pre strong{font-weight:400}
.verseblock .attribution{margin-top:1.25rem;margin-left:.5ex}
.quoteblock .attribution,.verseblock .attribution{font-size:.9375em;line-height:1.45;font-style:italic}
.quoteblock .attribution br,.verseblock .attribution br{display:none}
.quoteblock .attribution cite,.verseblock .attribution cite{display:block;letter-spacing:-.025em;color:rgba(0,0,0,.6)}
.quoteblock.abstract blockquote::before,.quoteblock.excerpt blockquote::before,.quoteblock .quoteblock blockquote::before{display:none}
.quoteblock.abstract blockquote,.quoteblock.abstract p,.quoteblock.excerpt blockquote,.quoteblock.excerpt p,.quoteblock .quoteblock blockquote,.quoteblock .quoteblock p{line-height:1.6;word-spacing:0}
.quoteblock.abstract{margin:0 1em 1.25em;display:block}
.quoteblock.abstract>.title{margin:0 0 .375em;font-size:1.15em;text-align:center}
.quoteblock.excerpt>blockquote,.quoteblock .quoteblock{padding:0 0 .25em 1em;border-left:.25em solid #dddddf}
.quoteblock.excerpt,.quoteblock .quoteblock{margin-left:0}
.quoteblock.excerpt blockquote,.quoteblock.excerpt p,.quoteblock .quoteblock blockquote,.quoteblock .quoteblock p{color:inherit;font-size:1.0625rem}
.quoteblock.excerpt .attribution,.quoteblock .quoteblock .attribution{color:inherit;font-size:.85rem;text-align:left;margin-right:0}
p.tableblock:last-child{margin-bottom:0}
td.tableblock>.content{margin-bottom:1.25em;word-wrap:anywhere}
td.tableblock>.content>:last-child{margin-bottom:-1.25em}
table.tableblock,th.tableblock,td.tableblock{border:0 solid #dedede}
table.grid-all>*>tr>*{border-width:1px}
table.grid-cols>*>tr>*{border-width:0 1px}
table.grid-rows>*>tr>*{border-width:1px 0}
table.frame-all{border-width:1px}
table.frame-ends{border-width:1px 0}
table.frame-sides{border-width:0 1px}
table.frame-none>colgroup+*>:first-child>*,table.frame-sides>colgroup+*>:first-child>*{border-top-width:0}
table.frame-none>:last-child>:last-child>*,table.frame-sides>:last-child>:last-child>*{border-bottom-width:0}
table.frame-none>*>tr>:first-child,table.frame-ends>*>tr>:first-child{border-left-width:0}
table.frame-none>*>tr>:last-child,table.frame-ends>*>tr>:last-child{border-right-width:0}
table.stripes-all>*>tr,table.stripes-odd>*>tr:nth-of-type(odd),table.stripes-even>*>tr:nth-of-type(even),table.stripes-hover>*>tr:hover{background:#f8f8f7}
th.halign-left,td.halign-left{text-align:left}
th.halign-right,td.halign-right{text-align:right}
th.halign-center,td.halign-center{text-align:center}
th.valign-top,td.valign-top{vertical-align:top}
th.valign-bottom,td.valign-bottom{vertical-align:bottom}
th.valign-middle,td.valign-middle{vertical-align:middle}
table thead th,table tfoot th{font-weight:bold}
tbody tr th{background:#f7f8f7}
tbody tr th,tbody tr th p,tfoot tr th,tfoot tr th p{color:rgba(0,0,0,.8);font-weight:bold}
p.tableblock>code:only-child{background:none;padding:0}
p.tableblock{font-size:1em}
ol{margin-left:1.75em}
ul li ol{margin-left:1.5em}
dl dd{margin-left:1.125em}
dl dd:last-child,dl dd:last-child>:last-child{margin-bottom:0}
li p,ul dd,ol dd,.olist .olist,.ulist .ulist,.ulist .olist,.olist .ulist{margin-bottom:.625em}
ul.checklist,ul.none,ol.none,ul.no-bullet,ol.no-bullet,ol.unnumbered,ul.unstyled,ol.unstyled{list-style-type:none}
ul.no-bullet,ol.no-bullet,ol.unnumbered{margin-left:.625em}
ul.unstyled,ol.unstyled{margin-left:0}
li>p:empty:only-child::before{content:"";display:inline-block}
ul.checklist>li>p:first-child{margin-left:-1em}
ul.checklist>li>p:first-child>.fa-square-o:first-child,ul.checklist>li>p:first-child>.fa-check-square-o:first-child{width:1.25em;font-size:.8em;position:relative;bottom:.125em}
ul.checklist>li>p:first-child>input[type=checkbox]:first-child{margin-right:.25em}
ul.inline{display:flex;flex-flow:row wrap;list-style:none;margin:0 0 .625em -1.25em}
ul.inline>li{margin-left:1.25em}
.unstyled dl dt{font-weight:400;font-style:normal}
ol.arabic{list-style-type:decimal}
ol.decimal{list-style-type:decimal-leading-zero}
ol.loweralpha{list-style-type:lower-alpha}
ol.upperalpha{list-style-type:upper-alpha}
ol.lowerroman{list-style-type:lower-roman}
ol.upperroman{list-style-type:upper-roman}
ol.lowergreek{list-style-type:lower-greek}
.hdlist>table,.colist>table{border:0;background:none}
.hdlist>table>tbody>tr,.colist>table>tbody>tr{background:none}
td.hdlist1,td.hdlist2{vertical-align:top;padding:0 .625em}
td.hdlist1{font-weight:bold;padding-bottom:1.25em}
td.hdlist2{word-wrap:anywhere}
.literalblock+.colist,.listingblock+.colist{margin-top:-.5em}
.colist td:not([class]):first-child{padding:.4em .75em 0;line-height:1;vertical-align:top}
.colist td:not([class]):first-child img{max-width:none}
.colist td:not([class]):last-child{padding:.25em 0}
.thumb,.th{line-height:0;display:inline-block;border:4px solid #fff;box-shadow:0 0 0 1px #ddd}
.imageblock.left{margin:.25em .625em 1.25em 0}
.imageblock.right{margin:.25em 0 1.25em .625em}
.imageblock>.title{margin-bottom:0}
.imageblock.thumb,.imageblock.th{border-width:6px}
.imageblock.thumb>.title,.imageblock.th>.title{padding:0 .125em}
.image.left,.image.right{margin-top:.25em;margin-bottom:.25em;display:inline-block;line-height:0}
.image.left{margin-right:.625em}
.image.right{margin-left:.625em}
a.image{text-decoration:none;display:inline-block}
a.image object{pointer-events:none}
sup.footnote,sup.footnoteref{font-size:.875em;position:static;vertical-align:super}
sup.footnote a,sup.footnoteref a{text-decoration:none}
sup.footnote a:active,sup.footnoteref a:active,#footnotes .footnote a:first-of-type:active{text-decoration:underline}
#footnotes{padding-top:.75em;padding-bottom:.75em;margin-bottom:.625em}
#footnotes hr{width:20%;min-width:6.25em;margin:-.25em 0 .75em;border-width:1px 0 0}
#footnotes .footnote{padding:0 .375em 0 .225em;line-height:1.3334;font-size:.875em;margin-left:1.2em;margin-bottom:.2em}
#footnotes .footnote a:first-of-type{font-weight:bold;text-decoration:none;margin-left:-1.05em}
#footnotes .footnote:last-of-type{margin-bottom:0}
#content #footnotes{margin-top:-.625em;margin-bottom:0;padding:.75em 0}
div.unbreakable{page-break-inside:avoid}
.big{font-size:larger}
.small{font-size:smaller}
.underline{text-decoration:underline}
.overline{text-decoration:overline}
.line-through{text-decoration:line-through}
.aqua{color:#00bfbf}
.aqua-background{background:#00fafa}
.black{color:#000}
.black-background{background:#000}
.blue{color:#0000bf}
.blue-background{background:#0000fa}
.fuchsia{color:#bf00bf}
.fuchsia-background{background:#fa00fa}
.gray{color:#606060}
.gray-background{background:#7d7d7d}
.green{color:#006000}
.green-background{background:#007d00}
.lime{color:#00bf00}
.lime-background{background:#00fa00}
.maroon{color:#600000}
.maroon-background{background:#7d0000}
.navy{color:#000060}
.navy-background{background:#00007d}
.olive{color:#606000}
.olive-background{background:#7d7d00}
.purple{color:#600060}
.purple-background{background:#7d007d}
.red{color:#bf0000}
.red-background{background:#fa0000}
.silver{color:#909090}
.silver-background{background:#bcbcbc}
.teal{color:#006060}
.teal-background{background:#007d7d}
.white{color:#bfbfbf}
.white-background{background:#fafafa}
.yellow{color:#bfbf00}
.yellow-background{background:#fafa00}
span.icon>.fa{cursor:default}
a span.icon>.fa{cursor:inherit}
.admonitionblock td.icon [class^="fa icon-"]{font-size:2.5em;text-shadow:1px 1px 2px rgba(0,0,0,.5);cursor:default}
.admonitionblock td.icon .icon-note::before{content:"\f05a";color:#19407c}
.admonitionblock td.icon .icon-tip::before{content:"\f0eb";text-shadow:1px 1px 2px rgba(155,155,0,.8);color:#111}
.admonitionblock td.icon .icon-warning::before{content:"\f071";color:#bf6900}
.admonitionblock td.icon .icon-caution::before{content:"\f06d";color:#bf3400}
.admonitionblock td.icon .icon-important::before{content:"\f06a";color:#bf0000}
.conum[data-value]{display:inline-block;color:#fff!important;background:rgba(0,0,0,.8);border-radius:50%;text-align:center;font-size:.75em;width:1.67em;height:1.67em;line-height:1.67em;font-family:"Open Sans","DejaVu Sans",sans-serif;font-style:normal;font-weight:bold}
.conum[data-value] *{color:#fff!important}
.conum[data-value]+b{display:none}
.conum[data-value]::after{content:attr(data-value)}
pre .conum[data-value]{position:relative;top:-.125em}
b.conum *{color:inherit!important}
.conum:not([data-value]):empty{display:none}
dt,th.tableblock,td.content,div.footnote{text-rendering:optimizeLegibility}
h1,h2,p,td.content,span.alt,summary{letter-spacing:-.01em}
p strong,td.content strong,div.footnote strong{letter-spacing:-.005em}
p,blockquote,dt,td.content,td.hdlist1,span.alt,summary{font-size:1.0625rem}
p{margin-bottom:1.25rem}
.sidebarblock p,.sidebarblock dt,.sidebarblock td.content,p.tableblock{font-size:1em}
.exampleblock>.content{background:#fffef7;border-color:#e0e0dc;box-shadow:0 1px 4px #e0e0dc}
.print-only{display:none!important}
@page{margin:1.25cm .75cm}
@media print{*{box-shadow:none!important;text-shadow:none!important}
html{font-size:80%}
a{color:inherit!important;text-decoration:underline!important}
a.bare,a[href^="#"],a[href^="mailto:"]{text-decoration:none!important}
a[href^="http:"]:not(.bare)::after,a[href^="https:"]:not(.bare)::after{content:"(" attr(href) ")";display:inline-block;font-size:.875em;padding-left:.25em}
abbr[title]{border-bottom:1px dotted}
abbr[title]::after{content:" (" attr(title) ")"}
pre,blockquote,tr,img,object,svg{page-break-inside:avoid}
thead{display:table-header-group}
svg{max-width:100%}
p,blockquote,dt,td.content{font-size:1em;orphans:3;widows:3}
h2,h3,#toctitle,.sidebarblock>.content>.title{page-break-after:avoid}
#header,#content,#footnotes,#footer{max-width:none}
#toc,.sidebarblock,.exampleblock>.content{background:none!important}
#toc{border-bottom:1px solid #dddddf!important;padding-bottom:0!important}
body.book #header{text-align:center}
body.book #header>h1:first-child{border:0!important;margin:2.5em 0 1em}
body.book #header .details{border:0!important;display:block;padding:0!important}
body.book #header .details span:first-child{margin-left:0!important}
body.book #header .details br{display:block}
body.book #header .details br+span::before{content:none!important}
body.book #toc{border:0!important;text-align:left!important;padding:0!important;margin:0!important}
body.book #toc,body.book #preamble,body.book h1.sect0,body.book .sect1>h2{page-break-before:always}
.listingblock code[data-lang]::before{display:block}
#footer{padding:0 .9375em}
.hide-on-print{display:none!important}
.print-only{display:block!important}
.hide-for-print{display:none!important}
.show-for-print{display:inherit!important}}
@media amzn-kf8,print{#header>h1:first-child{margin-top:1.25rem}
.sect1{padding:0!important}
.sect1+.sect1{border:0}
#footer{background:none}
#footer-text{color:rgba(0,0,0,.6);font-size:.9em}}
@media amzn-kf8{#header,#content,#footnotes,#footer{padding:0}}
</style>
<style>
pre.rouge table td { padding: 5px; }
pre.rouge table pre { margin: 0; }
pre.rouge, pre.rouge .w {
color: #24292f;
background-color: #f6f8fa;
}
pre.rouge .k, pre.rouge .kd, pre.rouge .kn, pre.rouge .kp, pre.rouge .kr, pre.rouge .kt, pre.rouge .kv {
color: #cf222e;
}
pre.rouge .gr {
color: #f6f8fa;
}
pre.rouge .gd {
color: #82071e;
background-color: #ffebe9;
}
pre.rouge .nb {
color: #953800;
}
pre.rouge .nc {
color: #953800;
}
pre.rouge .no {
color: #953800;
}
pre.rouge .nn {
color: #953800;
}
pre.rouge .sr {
color: #116329;
}
pre.rouge .na {
color: #116329;
}
pre.rouge .nt {
color: #116329;
}
pre.rouge .gi {
color: #116329;
background-color: #dafbe1;
}
pre.rouge .ges {
font-weight: bold;
font-style: italic;
}
pre.rouge .kc {
color: #0550ae;
}
pre.rouge .l, pre.rouge .ld, pre.rouge .m, pre.rouge .mb, pre.rouge .mf, pre.rouge .mh, pre.rouge .mi, pre.rouge .il, pre.rouge .mo, pre.rouge .mx {
color: #0550ae;
}
pre.rouge .sb {
color: #0550ae;
}
pre.rouge .bp {
color: #0550ae;
}
pre.rouge .ne {
color: #0550ae;
}
pre.rouge .nl {
color: #0550ae;
}
pre.rouge .py {
color: #0550ae;
}
pre.rouge .nv, pre.rouge .vc, pre.rouge .vg, pre.rouge .vi, pre.rouge .vm {
color: #0550ae;
}
pre.rouge .o, pre.rouge .ow {
color: #0550ae;
}
pre.rouge .gh {
color: #0550ae;
font-weight: bold;
}
pre.rouge .gu {
color: #0550ae;
font-weight: bold;
}
pre.rouge .s, pre.rouge .sa, pre.rouge .sc, pre.rouge .dl, pre.rouge .sd, pre.rouge .s2, pre.rouge .se, pre.rouge .sh, pre.rouge .sx, pre.rouge .s1, pre.rouge .ss {
color: #0a3069;
}
pre.rouge .nd {
color: #8250df;
}
pre.rouge .nf, pre.rouge .fm {
color: #8250df;
}
pre.rouge .err {
color: #f6f8fa;
background-color: #82071e;
}
pre.rouge .c, pre.rouge .ch, pre.rouge .cd, pre.rouge .cm, pre.rouge .cp, pre.rouge .cpf, pre.rouge .c1, pre.rouge .cs {
color: #6e7781;
}
pre.rouge .gl {
color: #6e7781;
}
pre.rouge .gt {
color: #6e7781;
}
pre.rouge .ni {
color: #24292f;
}
pre.rouge .si {
color: #24292f;
}
pre.rouge .ge {
color: #24292f;
font-style: italic;
}
pre.rouge .gs {
color: #24292f;
font-weight: bold;
}
</style>
</head>
<body class="book toc2 toc-left">
<div id="header">
<h1>AnnNet Specification</h1>
<div class="details">
<span id="author" class="author">Brent Saner</span><br>
<span id="email" class="email"><a href="mailto:bts@square-r00t.net">bts@square-r00t.net</a></span><br>
<span id="revdate">Last rendered 2025-08-28 07:46:15 -0400</span>
</div>
<div id="toc" class="toc2">
<div id="toctitle">Table of Contents</div>
<ul class="sectlevel1">
<li><a href="#license">1. License</a></li>
<li><a href="#lib">2. Reference Library</a></li>
<li><a href="#disclaimer">3. Disclaimer</a>
<ul class="sectlevel2">
<li><a href="#disc_proto">3.1. The AnnNet Protocol</a></li>
<li><a href="#disc_ref">3.2. References</a></li>
</ul>
</li>
<li><a href="#proto">4. Protocol</a></li>
<li><a href="#spec">5. Specification</a>
<ul class="sectlevel2">
<li><a href="#spec_msg">5.1. AnnNet Message Format</a>
<ul class="sectlevel3">
<li><a href="#spec_msg_pfx">5.1.1. Standard Prefix</a>
<ul class="sectlevel4">
<li><a href="#spec_msg_pfx_ver">5.1.1.1. Version</a>
<ul class="sectlevel5">
<li><a href="#spec_msg_pfx_ver_maj">5.1.1.1.1. Major</a></li>
<li><a href="#spec_msg_pfx_ver_min">5.1.1.1.2. Minor</a></li>
<li><a href="#spec_msg_pfx_ver_patch">5.1.1.1.3. Patch</a></li>
<li><a href="#spec_msg_pfx_ver_flags">5.1.1.1.4. Release Flag(s)</a></li>
</ul>
</li>
<li><a href="#spec_msg_pfx_len">5.1.1.2. Payload Length</a></li>
</ul>
</li>
<li><a href="#spec_msg_payload">5.1.2. Payload</a></li>
</ul>
</li>
<li><a href="#spec_link">5.2. AnnNet Link</a></li>
<li><a href="#spec_bcast">5.3. AnnNet Broadcast</a>
<ul class="sectlevel3">
<li><a href="#spec_bcast_v4">5.3.1. IPv4</a>
<ul class="sectlevel4">
<li><a href="#spec_bcast_v4_msg">5.3.1.1. Message Format</a></li>
</ul>
</li>
<li><a href="#spec_bcast_v6">5.3.2. IPv6</a>
<ul class="sectlevel4">
<li><a href="#spec_bcast_v6_msg">5.3.2.1. Message Format</a></li>
</ul>
</li>
<li><a href="#spec_bcast_protonum">5.3.3. Internet Protocol Number</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="#limits">6. Limitations</a></li>
<li><a href="#fq">7. (F)AQ/FUQ (Anticipated, Frequently Asked/Anticipated/Unasked Questions)</a>
<ul class="sectlevel2">
<li><a href="#fq_tcpip">7.1. Why do you reference the OSI model instead of the TCP/IP model? It&#8217;s old/outdated/inaccurate.</a></li>
<li><a href="#fq_proto">7.2. Why Shouldn&#8217;t I Use AnnNet for Regular Traffic?</a></li>
</ul>
</li>
<li><a href="#xtra">8. Addendum/Errata/Administrivia</a>
<ul class="sectlevel2">
<li><a href="#xtra_bitpacked">8.1. Bitpacked Fields</a>
<ul class="sectlevel3">
<li><a href="#xtra_bitpacked_vihl">8.1.1. IP Version, IHL (IPv4)</a></li>
<li><a href="#xtra_bitpacked_de">8.1.2. DSCP, ECN (IPv4)</a></li>
<li><a href="#xtra_bitpacked_frag">8.1.3. Flags, Fragmentation Offset (IPv4)</a></li>
<li><a href="#xtra_bitpacked_vtf">8.1.4. IP Version, Traffic Class, Flow Label (IPv6)</a></li>
</ul>
</li>
</ul>
</li>
</ul>
</div>
</div>
<div id="content">
<div class="sect1">
<h2 id="license"><a class="link" href="#license">1. License</a></h2>
<div class="sectionbody">
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>AnnNet Specification License</title>
<!-- <link rel="stylesheet" href="style.css"> -->
<!-- <script src="script.js"></script> -->
</head>
<body>
<p>
<a property="dct:title"
rel="cc:attributionURL"
href="https://annnet.io">
AnnNet Specification
</a> by
<a rel="cc:attributionURL dct:creator"
property="cc:attributionName"
href="https://r00t2.io">
Brent Saner
</a> is licensed under:
<br />
<br />
<a href="https://creativecommons.org/licenses/by-sa/4.0/?ref=chooser-v1"
target="_blank"
rel="license noopener noreferrer"
style="display:inline-block;">
Creative Commons Attribution-ShareAlike 4.0 International
<br />
<img style="height:22px!important;margin-left:3px;vertical-align:text-bottom;"
src="https://mirrors.creativecommons.org/presskit/icons/cc.svg?ref=chooser-v1"
alt="">
<img style="height:22px!important;margin-left:3px;vertical-align:text-bottom;"
src="https://mirrors.creativecommons.org/presskit/icons/by.svg?ref=chooser-v1"
alt="">
<img style="height:22px!important;margin-left:3px;vertical-align:text-bottom;"
src="https://mirrors.creativecommons.org/presskit/icons/sa.svg?ref=chooser-v1"
alt=""></a>
</p>
<p>
<details>
<summary>(License in full)</summary>
<pre>
Attribution-ShareAlike 4.0 International
=======================================================================
Creative Commons Corporation ("Creative Commons") is not a law firm and
does not provide legal services or legal advice. Distribution of
Creative Commons public licenses does not create a lawyer-client or
other relationship. Creative Commons makes its licenses and related
information available on an "as-is" basis. Creative Commons gives no
warranties regarding its licenses, any material licensed under their
terms and conditions, or any related information. Creative Commons
disclaims all liability for damages resulting from their use to the
fullest extent possible.
Using Creative Commons Public Licenses
Creative Commons public licenses provide a standard set of terms and
conditions that creators and other rights holders may use to share
original works of authorship and other material subject to copyright
and certain other rights specified in the public license below. The
following considerations are for informational purposes only, are not
exhaustive, and do not form part of our licenses.
Considerations for licensors: Our public licenses are
intended for use by those authorized to give the public
permission to use material in ways otherwise restricted by
copyright and certain other rights. Our licenses are
irrevocable. Licensors should read and understand the terms
and conditions of the license they choose before applying it.
Licensors should also secure all rights necessary before
applying our licenses so that the public can reuse the
material as expected. Licensors should clearly mark any
material not subject to the license. This includes other CC-
licensed material, or material used under an exception or
limitation to copyright. More considerations for licensors:
wiki.creativecommons.org/Considerations_for_licensors
Considerations for the public: By using one of our public
licenses, a licensor grants the public permission to use the
licensed material under specified terms and conditions. If
the licensor's permission is not necessary for any reason--for
example, because of any applicable exception or limitation to
copyright--then that use is not regulated by the license. Our
licenses grant only permissions under copyright and certain
other rights that a licensor has authority to grant. Use of
the licensed material may still be restricted for other
reasons, including because others have copyright or other
rights in the material. A licensor may make special requests,
such as asking that all changes be marked or described.
Although not required by our licenses, you are encouraged to
respect those requests where reasonable. More considerations
for the public:
wiki.creativecommons.org/Considerations_for_licensees
=======================================================================
Creative Commons Attribution-ShareAlike 4.0 International Public
License
By exercising the Licensed Rights (defined below), You accept and agree
to be bound by the terms and conditions of this Creative Commons
Attribution-ShareAlike 4.0 International Public License ("Public
License"). To the extent this Public License may be interpreted as a
contract, You are granted the Licensed Rights in consideration of Your
acceptance of these terms and conditions, and the Licensor grants You
such rights in consideration of benefits the Licensor receives from
making the Licensed Material available under these terms and
conditions.
Section 1 -- Definitions.
a. Adapted Material means material subject to Copyright and Similar
Rights that is derived from or based upon the Licensed Material
and in which the Licensed Material is translated, altered,
arranged, transformed, or otherwise modified in a manner requiring
permission under the Copyright and Similar Rights held by the
Licensor. For purposes of this Public License, where the Licensed
Material is a musical work, performance, or sound recording,
Adapted Material is always produced where the Licensed Material is
synched in timed relation with a moving image.
b. Adapter's License means the license You apply to Your Copyright
and Similar Rights in Your contributions to Adapted Material in
accordance with the terms and conditions of this Public License.
c. BY-SA Compatible License means a license listed at
creativecommons.org/compatiblelicenses, approved by Creative
Commons as essentially the equivalent of this Public License.
d. Copyright and Similar Rights means copyright and/or similar rights
closely related to copyright including, without limitation,
performance, broadcast, sound recording, and Sui Generis Database
Rights, without regard to how the rights are labeled or
categorized. For purposes of this Public License, the rights
specified in Section 2(b)(1)-(2) are not Copyright and Similar
Rights.
e. Effective Technological Measures means those measures that, in the
absence of proper authority, may not be circumvented under laws
fulfilling obligations under Article 11 of the WIPO Copyright
Treaty adopted on December 20, 1996, and/or similar international
agreements.
f. Exceptions and Limitations means fair use, fair dealing, and/or
any other exception or limitation to Copyright and Similar Rights
that applies to Your use of the Licensed Material.
g. License Elements means the license attributes listed in the name
of a Creative Commons Public License. The License Elements of this
Public License are Attribution and ShareAlike.
h. Licensed Material means the artistic or literary work, database,
or other material to which the Licensor applied this Public
License.
i. Licensed Rights means the rights granted to You subject to the
terms and conditions of this Public License, which are limited to
all Copyright and Similar Rights that apply to Your use of the
Licensed Material and that the Licensor has authority to license.
j. Licensor means the individual(s) or entity(ies) granting rights
under this Public License.
k. Share means to provide material to the public by any means or
process that requires permission under the Licensed Rights, such
as reproduction, public display, public performance, distribution,
dissemination, communication, or importation, and to make material
available to the public including in ways that members of the
public may access the material from a place and at a time
individually chosen by them.
l. Sui Generis Database Rights means rights other than copyright
resulting from Directive 96/9/EC of the European Parliament and of
the Council of 11 March 1996 on the legal protection of databases,
as amended and/or succeeded, as well as other essentially
equivalent rights anywhere in the world.
m. You means the individual or entity exercising the Licensed Rights
under this Public License. Your has a corresponding meaning.
Section 2 -- Scope.
a. License grant.
1. Subject to the terms and conditions of this Public License,
the Licensor hereby grants You a worldwide, royalty-free,
non-sublicensable, non-exclusive, irrevocable license to
exercise the Licensed Rights in the Licensed Material to:
a. reproduce and Share the Licensed Material, in whole or
in part; and
b. produce, reproduce, and Share Adapted Material.
2. Exceptions and Limitations. For the avoidance of doubt, where
Exceptions and Limitations apply to Your use, this Public
License does not apply, and You do not need to comply with
its terms and conditions.
3. Term. The term of this Public License is specified in Section
6(a).
4. Media and formats; technical modifications allowed. The
Licensor authorizes You to exercise the Licensed Rights in
all media and formats whether now known or hereafter created,
and to make technical modifications necessary to do so. The
Licensor waives and/or agrees not to assert any right or
authority to forbid You from making technical modifications
necessary to exercise the Licensed Rights, including
technical modifications necessary to circumvent Effective
Technological Measures. For purposes of this Public License,
simply making modifications authorized by this Section 2(a)
(4) never produces Adapted Material.
5. Downstream recipients.
a. Offer from the Licensor -- Licensed Material. Every
recipient of the Licensed Material automatically
receives an offer from the Licensor to exercise the
Licensed Rights under the terms and conditions of this
Public License.
b. Additional offer from the Licensor -- Adapted Material.
Every recipient of Adapted Material from You
automatically receives an offer from the Licensor to
exercise the Licensed Rights in the Adapted Material
under the conditions of the Adapter's License You apply.
c. No downstream restrictions. You may not offer or impose
any additional or different terms or conditions on, or
apply any Effective Technological Measures to, the
Licensed Material if doing so restricts exercise of the
Licensed Rights by any recipient of the Licensed
Material.
6. No endorsement. Nothing in this Public License constitutes or
may be construed as permission to assert or imply that You
are, or that Your use of the Licensed Material is, connected
with, or sponsored, endorsed, or granted official status by,
the Licensor or others designated to receive attribution as
provided in Section 3(a)(1)(A)(i).
b. Other rights.
1. Moral rights, such as the right of integrity, are not
licensed under this Public License, nor are publicity,
privacy, and/or other similar personality rights; however, to
the extent possible, the Licensor waives and/or agrees not to
assert any such rights held by the Licensor to the limited
extent necessary to allow You to exercise the Licensed
Rights, but not otherwise.
2. Patent and trademark rights are not licensed under this
Public License.
3. To the extent possible, the Licensor waives any right to
collect royalties from You for the exercise of the Licensed
Rights, whether directly or through a collecting society
under any voluntary or waivable statutory or compulsory
licensing scheme. In all other cases the Licensor expressly
reserves any right to collect such royalties.
Section 3 -- License Conditions.
Your exercise of the Licensed Rights is expressly made subject to the
following conditions.
a. Attribution.
1. If You Share the Licensed Material (including in modified
form), You must:
a. retain the following if it is supplied by the Licensor
with the Licensed Material:
i. identification of the creator(s) of the Licensed
Material and any others designated to receive
attribution, in any reasonable manner requested by
the Licensor (including by pseudonym if
designated);
ii. a copyright notice;
iii. a notice that refers to this Public License;
iv. a notice that refers to the disclaimer of
warranties;
v. a URI or hyperlink to the Licensed Material to the
extent reasonably practicable;
b. indicate if You modified the Licensed Material and
retain an indication of any previous modifications; and
c. indicate the Licensed Material is licensed under this
Public License, and include the text of, or the URI or
hyperlink to, this Public License.
2. You may satisfy the conditions in Section 3(a)(1) in any
reasonable manner based on the medium, means, and context in
which You Share the Licensed Material. For example, it may be
reasonable to satisfy the conditions by providing a URI or
hyperlink to a resource that includes the required
information.
3. If requested by the Licensor, You must remove any of the
information required by Section 3(a)(1)(A) to the extent
reasonably practicable.
b. ShareAlike.
In addition to the conditions in Section 3(a), if You Share
Adapted Material You produce, the following conditions also apply.
1. The Adapter's License You apply must be a Creative Commons
license with the same License Elements, this version or
later, or a BY-SA Compatible License.
2. You must include the text of, or the URI or hyperlink to, the
Adapter's License You apply. You may satisfy this condition
in any reasonable manner based on the medium, means, and
context in which You Share Adapted Material.
3. You may not offer or impose any additional or different terms
or conditions on, or apply any Effective Technological
Measures to, Adapted Material that restrict exercise of the
rights granted under the Adapter's License You apply.
Section 4 -- Sui Generis Database Rights.
Where the Licensed Rights include Sui Generis Database Rights that
apply to Your use of the Licensed Material:
a. for the avoidance of doubt, Section 2(a)(1) grants You the right
to extract, reuse, reproduce, and Share all or a substantial
portion of the contents of the database;
b. if You include all or a substantial portion of the database
contents in a database in which You have Sui Generis Database
Rights, then the database in which You have Sui Generis Database
Rights (but not its individual contents) is Adapted Material,
including for purposes of Section 3(b); and
c. You must comply with the conditions in Section 3(a) if You Share
all or a substantial portion of the contents of the database.
For the avoidance of doubt, this Section 4 supplements and does not
replace Your obligations under this Public License where the Licensed
Rights include other Copyright and Similar Rights.
Section 5 -- Disclaimer of Warranties and Limitation of Liability.
a. UNLESS OTHERWISE SEPARATELY UNDERTAKEN BY THE LICENSOR, TO THE
EXTENT POSSIBLE, THE LICENSOR OFFERS THE LICENSED MATERIAL AS-IS
AND AS-AVAILABLE, AND MAKES NO REPRESENTATIONS OR WARRANTIES OF
ANY KIND CONCERNING THE LICENSED MATERIAL, WHETHER EXPRESS,
IMPLIED, STATUTORY, OR OTHER. THIS INCLUDES, WITHOUT LIMITATION,
WARRANTIES OF TITLE, MERCHANTABILITY, FITNESS FOR A PARTICULAR
PURPOSE, NON-INFRINGEMENT, ABSENCE OF LATENT OR OTHER DEFECTS,
ACCURACY, OR THE PRESENCE OR ABSENCE OF ERRORS, WHETHER OR NOT
KNOWN OR DISCOVERABLE. WHERE DISCLAIMERS OF WARRANTIES ARE NOT
ALLOWED IN FULL OR IN PART, THIS DISCLAIMER MAY NOT APPLY TO YOU.
b. TO THE EXTENT POSSIBLE, IN NO EVENT WILL THE LICENSOR BE LIABLE
TO YOU ON ANY LEGAL THEORY (INCLUDING, WITHOUT LIMITATION,
NEGLIGENCE) OR OTHERWISE FOR ANY DIRECT, SPECIAL, INDIRECT,
INCIDENTAL, CONSEQUENTIAL, PUNITIVE, EXEMPLARY, OR OTHER LOSSES,
COSTS, EXPENSES, OR DAMAGES ARISING OUT OF THIS PUBLIC LICENSE OR
USE OF THE LICENSED MATERIAL, EVEN IF THE LICENSOR HAS BEEN
ADVISED OF THE POSSIBILITY OF SUCH LOSSES, COSTS, EXPENSES, OR
DAMAGES. WHERE A LIMITATION OF LIABILITY IS NOT ALLOWED IN FULL OR
IN PART, THIS LIMITATION MAY NOT APPLY TO YOU.
c. The disclaimer of warranties and limitation of liability provided
above shall be interpreted in a manner that, to the extent
possible, most closely approximates an absolute disclaimer and
waiver of all liability.
Section 6 -- Term and Termination.
a. This Public License applies for the term of the Copyright and
Similar Rights licensed here. However, if You fail to comply with
this Public License, then Your rights under this Public License
terminate automatically.
b. Where Your right to use the Licensed Material has terminated under
Section 6(a), it reinstates:
1. automatically as of the date the violation is cured, provided
it is cured within 30 days of Your discovery of the
violation; or
2. upon express reinstatement by the Licensor.
For the avoidance of doubt, this Section 6(b) does not affect any
right the Licensor may have to seek remedies for Your violations
of this Public License.
c. For the avoidance of doubt, the Licensor may also offer the
Licensed Material under separate terms or conditions or stop
distributing the Licensed Material at any time; however, doing so
will not terminate this Public License.
d. Sections 1, 5, 6, 7, and 8 survive termination of this Public
License.
Section 7 -- Other Terms and Conditions.
a. The Licensor shall not be bound by any additional or different
terms or conditions communicated by You unless expressly agreed.
b. Any arrangements, understandings, or agreements regarding the
Licensed Material not stated herein are separate from and
independent of the terms and conditions of this Public License.
Section 8 -- Interpretation.
a. For the avoidance of doubt, this Public License does not, and
shall not be interpreted to, reduce, limit, restrict, or impose
conditions on any use of the Licensed Material that could lawfully
be made without permission under this Public License.
b. To the extent possible, if any provision of this Public License is
deemed unenforceable, it shall be automatically reformed to the
minimum extent necessary to make it enforceable. If the provision
cannot be reformed, it shall be severed from this Public License
without affecting the enforceability of the remaining terms and
conditions.
c. No term or condition of this Public License will be waived and no
failure to comply consented to unless expressly agreed to by the
Licensor.
d. Nothing in this Public License constitutes or may be interpreted
as a limitation upon, or waiver of, any privileges and immunities
that apply to the Licensor or You, including from the legal
processes of any jurisdiction or authority.
=======================================================================
Creative Commons is not a party to its public
licenses. Notwithstanding, Creative Commons may elect to apply one of
its public licenses to material it publishes and in those instances
will be considered the “Licensor.” The text of the Creative Commons
public licenses is dedicated to the public domain under the CC0 Public
Domain Dedication. Except for the limited purpose of indicating that
material is shared under a Creative Commons public license or as
otherwise permitted by the Creative Commons policies published at
creativecommons.org/policies, Creative Commons does not authorize the
use of the trademark "Creative Commons" or any other trademark or logo
of Creative Commons without its prior written consent including,
without limitation, in connection with any unauthorized modifications
to any of its public licenses or any other arrangements,
understandings, or agreements concerning use of licensed material. For
the avoidance of doubt, this paragraph does not form part of the
public licenses.
Creative Commons may be contacted at creativecommons.org.
</pre>
</details>
</p>
</body>
</html>
<div class="paragraph">
<p>In a nutshell, this means any may:</p>
</div>
<div class="ulist">
<ul>
<li>
<p>Use it in commercial/proprietary/internal works&#8230;&#8203;</p>
</li>
<li>
<p>Expand upon/change the specification&#8230;&#8203;</p>
<div class="ulist">
<ul>
<li>
<p>(As long as it is released under the same Creative Commons license)</p>
</li>
</ul>
</div>
</li>
</ul>
</div>
<div class="paragraph">
<p>As long as you attribute the original (this document). This can be as simple as something like:</p>
</div>
<div class="exampleblock">
<div class="content">
<div class="paragraph">
<p>Based on AnnNet version &lt;protocol version&gt; as found at <a href="https://annnet.io/" class="bare">https://annnet.io/</a>.</p>
</div>
</div>
</div>
<div class="paragraph">
<p>More details certainly helps, though; you may want to mention the exact date you "forked" it, etc.</p>
</div>
<div class="paragraph">
<p>Please see the full text as collapsed above or <a href="https://creativecommons.org/licenses/by-sa/4.0/legalcode.en" target="_blank" rel="noopener">the online version</a> of the license for full legal copy.</p>
</div>
<div class="admonitionblock note">
<table>
<tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">
In the event of the embedded text in this document differing from the online version, the online version is assumed to take precedence as the valid license applicable to this work.
</td>
</tr>
</table>
</div>
</div>
</div>
<div class="sect1">
<h2 id="lib"><a class="link" href="#lib">2. Reference Library</a></h2>
<div class="sectionbody">
<div class="paragraph">
<p>The AnnNet Protocol is accompanied by a reference library for Golang, <a href="https://pkg.go.dev/r00t2.io/annnet" target="_blank" rel="noopener">"AnnNet"</a> (<a href="https://git.r00t2.io/r00t2/go_annnet" target="_blank" rel="noopener"><em>source</em></a>):</p>
</div>
<a href="https://pkg.go.dev/go.pkg.dev/r00t2.io/annnet">
<img src="https://pkg.go.dev/badge/go.pkg.dev/r00t2.io/annnet.svg"
alt="Go Reference">
</a>
<br />
<br />
<div class="paragraph">
<p>It contains a reference "client" (listener), <a href="https://pkg.go.dev/r00t2.io/annnet/annie" target="_blank" rel="noopener"><code>annie</code></a> (<a href="https://git.r00t2.io/r00t2/go_annnet/src/branch/master/cmd/annie" target="_blank" rel="noopener"><em>source</em></a>), and a reference "server" (announcer), <a href="https://pkg.go.dev/r00t2.io/annnet/anna" target="_blank" rel="noopener"><code>anna</code></a> (<a href="https://git.r00t2.io/r00t2/go_annnet/src/branch/master/cmd/annie" target="_blank" rel="noopener"><em>source</em></a>).</p>
</div>
<div class="paragraph">
<p>Additional reference libraries may be available in the future.</p>
</div>
</div>
</div>
<div class="sect1">
<h2 id="disclaimer"><a class="link" href="#disclaimer">3. Disclaimer</a></h2>
<div class="sectionbody">
<div class="sect2">
<h3 id="disc_proto"><a class="link" href="#disc_proto">3.1. The AnnNet Protocol</a></h3>
<div class="paragraph">
<p>This specification is provided as-is with no guarantees or obligations from this specification&#8217;s author(s).</p>
</div>
<div class="paragraph">
<p>The author(s) is/are not held liable for any damages caused by implementation/use of this protocol.</p>
</div>
<div class="paragraph">
<p>The AnnNet specification is subject to change, but changes are not considered definitive nor effective until/unless tied with/to a specific released version.</p>
</div>
</div>
<div class="sect2">
<h3 id="disc_ref"><a class="link" href="#disc_ref">3.2. References</a></h3>
<div class="paragraph">
<p>Many outside references are made throughout this document.</p>
</div>
<div class="ulist">
<ul>
<li>
<p>The author(s) is/are not sponsored by, contribute to, nor condone any of the resources mentioned unless otherwise specified.</p>
</li>
<li>
<p>The author(s) is/are not sponsored by, nor member(s),contributor(s), or sponsor of, nor condone any organizations or other entities listed or their actions unless otherwise specified.</p>
</li>
</ul>
</div>
<div class="paragraph">
<p>References are suggested as-is with no guarantees or obligations from this specification&#8217;s author(s).</p>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="proto"><a class="link" href="#proto">4. Protocol</a></h2>
<div class="sectionbody">
<div class="paragraph">
<p>The AnnNet (pronounced like the woman&#8217;s name "Annette") protocol is an announcement/query protocol designed for unspecified hosts on a local network. It is a shorthand for <em>"the <strong>Ann</strong>ouncement <strong>Net</strong>work Protocol"</em>.</p>
</div>
<div class="paragraph">
<p>AnnNet is designed to operate with or without IP addressing being available, as it can operate on layer 2, layer 3, or both to unknown/unspecified destinations.</p>
</div>
<div class="paragraph">
<p>It is intended as a sort of "announcement" mechanism for sending messages to all hosts on a <strong>locally-linked</strong> (or <strong>single-organization-controlled</strong>) network (such as bootstrapping large-scale layer 3 services/clusters). It was designed with service/implementation-specific host discovery in mind, though other uses are possible.</p>
</div>
<div class="paragraph">
<p>It is recommended that it is only used <strong>sparingly</strong> for <strong>small</strong> messages (such as cluster <strong>bootstrapping</strong> for new members or initial cluster assembly). <em>Operational</em> messages should occur on a well-defined transport layer (e.g. TCP).<br>
It is important to avoid the temptation of simply implementing ALL of a service&#8217;s communication via AnnNet, as this can quite easily overwhelm the physical network&#8217;s limitations as hosts participating in its communication grows. See the FAQ/FUQ entry <a href="#fq_proto">Why Shouldn&#8217;t I Use AnnNet for Regular Traffic?</a> for suggestions on how to manage actual service communication instead.</p>
</div>
<div class="admonitionblock note">
<table>
<tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">
<div class="paragraph">
<p>The <a href="https://en.wikipedia.org/wiki/OSI_model" target="_blank" rel="noopener">OSI (Open Systems Interconnection) model</a> is going to be referenced a fair bit in this document.</p>
</div>
<div class="paragraph">
<p>The linked Wikipedia article is a fantastic primer on it with a plethora of useful links, but if you&#8217;d like to read the authoritative material that&#8217;d be <a href="https://www.iso.org/standard/20269.html" target="_blank" rel="noopener">ISO/IEC 7498-1:1994</a>.</p>
</div>
<div class="paragraph">
<p>ISO/IEC 7498-1:1994 is one of the free-as-in-beer-for-digital-copy ISO/IEC standards available, provided you have an ISO account&#8201;&#8212;&#8201;which is also free to create and use. You can use the <em>Register</em> link at the bottom of <a href="https://www.iso.org/webstore/login" target="_blank" rel="noopener">ISO&#8217;s Webstore login</a> to create a new purchasing account.</p>
</div>
<div class="paragraph">
<p><a id="tcpip_guide"></a>Another fantastic reference for the OSI model (and all things networking) is <a href="http://www.tcpipguide.com/" target="_blank" rel="noopener">the TCP/IP Guide</a> by Charles M. Kozierok. <em>(I am not sponsored by nor condone the material found in that re)</em></p>
</div>
<div class="paragraph">
<p>It is available:</p>
</div>
<div class="ulist">
<ul>
<li>
<p>In its entirety for free (-as-in-beer) <a href="http://www.tcpipguide.com/free/index.htm" target="_blank" rel="noopener">online</a> (if you don&#8217;t mind the large amount of ads)</p>
<div class="ulist">
<ul>
<li>
<p>Note that the online version may not map perfectly to the print/PDF versions, and may have different wording.</p>
</li>
<li>
<p>I (Brent) highly recommend supporting the author by either using the donation links at the bottom of that page or purchasing/licensing a donwloaded PDF or print copy, see below.</p>
</li>
</ul>
</div>
</li>
<li>
<p>By purchasing a PDF download <a href="http://www.tcpipguide.com/la.htm" target="_blank" rel="noopener">directly from the author</a></p>
<div class="ulist">
<ul>
<li>
<p>Which also allows for <a href="http://www.tcpipguide.com/pricing.htm" target="_blank" rel="noopener">bulk licensing</a> of the e-book for orginaztional use.</p>
</li>
</ul>
</div>
</li>
<li>
<p>By purchasing a print and/or PDF copy <a href="https://nostarch.com/tcpip.htm" target="_blank" rel="noopener">from No Starch Press</a></p>
<div class="ulist">
<ul>
<li>
<p>As expected with all other No Starch Press book purchases, a print copy comes with a free digital/e-book copy.</p>
</li>
</ul>
</div>
</li>
</ul>
</div>
<div class="paragraph">
<p>I (Brent) have a physical copy from No Starch Press. I find myself referencing the PDF much more often, as it has some very useful document linking within it, but moreso because the print copy is a <strong>behemoth</strong> and is very bulky for anything but a bookshelf and seated-at-a-table reading/research!</p>
</div>
<div class="paragraph">
<p>The OSI model is covered in the <strong>TCP/IP Guide</strong> in <em>Part I-2</em> (chapters <strong>5</strong> to <strong>7</strong> inclusive), starting on <em>p.79</em>.<br>
If using the online version, <em>Part I-2</em> is summarized/starts <a href="http://www.tcpipguide.com/free/t_TheOpenSystemInterconnectionOSIReferenceModel.htm" target="_blank" rel="noopener">here</a>.</p>
</div>
</td>
</tr>
</table>
</div>
</div>
</div>
<div class="sect1">
<h2 id="spec"><a class="link" href="#spec">5. Specification</a></h2>
<div class="sectionbody">
<div class="paragraph">
<p>AnnNet supports two "sub-protocols":</p>
</div>
<div class="ulist">
<ul>
<li>
<p><a href="#spec_link">AnnNet Link</a></p>
</li>
<li>
<p><a href="#spec_bcast">AnnNet Broadcast</a></p>
</li>
</ul>
</div>
<div class="paragraph">
<p>Both make use of the <a href="#spec_msg_pfx">Standard Prefix</a>, though in different places of the frame/packet depending on their implementation. See each sub-protocol below for details.</p>
</div>
<div class="sect2">
<h3 id="spec_msg"><a class="link" href="#spec_msg">5.1. AnnNet Message Format</a></h3>
<div class="paragraph">
<p>The general format of an AnnNet message (excluding leading/surrounding/trailing frames, headers, etc.) is:</p>
</div>
<table class="tableblock frame-all grid-all stretch">
<caption class="title">Table 1. AnnNet Message</caption>
<colgroup>
<col style="width: 33.3333%;">
<col style="width: 66.6667%;">
</colgroup>
<tbody>
<tr>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong><a href="#spec_msg_pfx">Standard Prefix</a> (5 Bytes)</strong></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong><a href="#spec_msg_payload">Payload</a></strong></p></td>
</tr>
</tbody>
</table>
<div class="sect3">
<h4 id="spec_msg_pfx"><a class="link" href="#spec_msg_pfx">5.1.1. Standard Prefix</a></h4>
<div class="paragraph">
<p>AnnNet defines a specific prefix that must be added before a message. While AnnNet does not dictate the contents of the <strong>payload</strong> in any way, all AnnNet messages must contain this prefix.</p>
</div>
<div class="paragraph">
<p>In <a href="#spec_link">AnnNet Link</a>, it immediately follows the EtherType value.</p>
</div>
<div class="paragraph">
<p>In <a href="#spec_bcast">AnnNet Broadcast</a>, it immediately follows the IPv4/IPv6 header.</p>
</div>
<div class="paragraph">
<p>In its current form, this is:</p>
</div>
<table class="tableblock frame-all grid-all stretch">
<caption class="title">Table 2. AnnNet Prefix</caption>
<colgroup>
<col style="width: 20%;">
<col style="width: 20%;">
<col style="width: 20%;">
<col style="width: 20%;">
<col style="width: 20%;">
</colgroup>
<tbody>
<tr>
<td class="tableblock halign-center valign-middle" colspan="4"><p class="tableblock"><strong><a href="#spec_msg_pfx_ver">Version</a></strong></p></td>
<td class="tableblock halign-center valign-middle"></td>
</tr>
<tr>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong><a href="#spec_msg_pfx_ver_maj">Major</a></strong></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong><a href="#spec_msg_pfx_ver_min">Minor</a></strong></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong><a href="#spec_msg_pfx_ver_patch">Patch</a></strong></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong><a href="#spec_msg_pfx_ver_flags">Release Flag(s)</a></strong></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong><a href="#spec_msg_pfx_len">Payload Length</a></strong></p></td>
</tr>
</tbody>
</table>
<div class="sect4">
<h5 id="spec_msg_pfx_ver"><a class="link" href="#spec_msg_pfx_ver">5.1.1.1. Version</a></h5>
<table class="tableblock frame-all grid-all stretch">
<colgroup>
<col style="width: 25%;">
<col style="width: 75%;">
</colgroup>
<thead>
<tr>
<th class="tableblock halign-center valign-middle">Length (Octets/Bytes)</th>
<th class="tableblock halign-center valign-middle">Type</th>
</tr>
</thead>
<tbody>
<tr>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><code>4</code></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock">Big-Endian Unsigned 32-Bit Integer/Container</p></td>
</tr>
</tbody>
</table>
<div class="paragraph">
<p>The <strong>Version</strong> field matches the version of AnnNet being used.</p>
</div>
<div class="paragraph">
<p>Because AnnNet follows <a href="https://semver.org/" target="_blank" rel="noopener">Semantic Versioning</a> (v2.0.0) for its specification, this can either be treated as an abstract container (hereafter a "byte-slice version" in this spec) of individual bytes indicating each version sub-field or treated as a whole (hereafter a "single-value version" in this spec).</p>
</div>
<div class="paragraph">
<p>Thus for example, when determing how to parse the following fields from an AnnNet message if incompatible structuring changes are introduced, one can either:</p>
</div>
<div class="ulist">
<ul>
<li>
<p>Perform a version comparison sequentially (e.g. via first parsing and comparing the <a href="#spec_msg_pfx_ver_maj">Major</a>, and then moving on to the <a href="#spec_msg_pfx_ver_min">Minor</a>, and so forth) for a byte-slice version</p>
</li>
<li>
<p>Or for a single-value version, a direct integer comparison&#8201;&#8212;&#8201;for example, if a single-value <strong>Version</strong> is greater than or equal to <code>16777216</code> to check if it is greater than or equal to version <code>1.0.0</code> of AnnNet (<code>16777216</code> being equal to <code>0x01</code>, <code>0x00</code>, <code>0x00</code>, <code>0x00</code>, or more properly <code>0x01000000</code>, when big-endian decoded).</p>
</li>
</ul>
</div>
<div class="admonitionblock tip">
<table>
<tr>
<td class="icon">
<div class="title">Tip</div>
</td>
<td class="content">
<div class="paragraph">
<p>Bit-shifting can be used to extract individual version fields from a single-value version.</p>
</div>
<details>
<summary class="title">Example in Go</summary>
<div class="content">
<div class="listingblock">
<div class="title"><code>examples/extractversion.go</code></div>
<div class="content">
<pre class="rouge highlight"><code data-lang="go"><span class="k">package</span> <span class="n">main</span>
<span class="k">import</span> <span class="p">(</span>
<span class="s">"encoding/binary"</span>
<span class="s">"fmt"</span>
<span class="p">)</span>
<span class="k">const</span> <span class="p">(</span>
<span class="n">posMajor</span> <span class="kt">int</span> <span class="o">=</span> <span class="m">1</span> <span class="o">+</span> <span class="no">iota</span>
<span class="n">posMinor</span>
<span class="n">posPatch</span>
<span class="n">posRelFlag</span>
<span class="p">)</span>
<span class="k">var</span> <span class="p">(</span>
<span class="n">singleValVer</span> <span class="kt">uint32</span>
<span class="n">singleValVerBytes</span> <span class="p">[]</span><span class="kt">byte</span> <span class="o">=</span> <span class="p">[]</span><span class="kt">byte</span><span class="p">{</span>
<span class="m">0x01</span><span class="p">,</span> <span class="m">0x02</span><span class="p">,</span> <span class="m">0x03</span><span class="p">,</span> <span class="m">0x01</span><span class="p">,</span> <span class="c">// A version of 1.2.3 with the PreRelease release flag enabled</span>
<span class="p">}</span>
<span class="n">ord</span> <span class="n">binary</span><span class="o">.</span><span class="n">ByteOrder</span> <span class="o">=</span> <span class="n">binary</span><span class="o">.</span><span class="n">BigEndian</span>
<span class="p">)</span>
<span class="k">func</span> <span class="n">main</span><span class="p">()</span> <span class="p">{</span>
<span class="k">var</span> <span class="n">verVal</span> <span class="kt">uint8</span>
<span class="n">singleValVer</span> <span class="o">=</span> <span class="n">ord</span><span class="o">.</span><span class="n">Uint32</span><span class="p">(</span><span class="n">singleValVerBytes</span><span class="p">)</span>
<span class="c">// fmt's Printf, for some silly reason, strips leading 0's from hex formatting unless you explicitly pad or align precision.</span>
<span class="n">fmt</span><span class="o">.</span><span class="n">Printf</span><span class="p">(</span><span class="s">"%d</span><span class="se">\n</span><span class="s">%#.8x</span><span class="se">\n</span><span class="s">"</span><span class="p">,</span> <span class="n">singleValVer</span><span class="p">,</span> <span class="n">singleValVer</span><span class="p">)</span>
<span class="c">// Prints:</span>
<span class="c">/*
16909057
0x01020301
*/</span>
<span class="c">/*
The individual versions can be fetched by the following. This comment is an explanation of the condensed form below in code.
1. n = 8 * i // i is the version component you want. See the pos* constants at the top. 8 to align to a byte (8 bits).
2. offset = 32 - n // 32 because singleValVar is a uint32 (and thus 4 bytes, or 32 bits, in memory).
3. cmp = singleValVer &gt;&gt; offset // Shift to the bit offset we're interested in.
4. val32 = cmp &amp; 0xff // It's then AND'd with 0xff (256) to get the set bits -- but still a uint32, so
5. verVal = uint8(val32)
*/</span>
<span class="c">// For example:</span>
<span class="k">for</span> <span class="n">i</span><span class="p">,</span> <span class="n">verNm</span> <span class="o">:=</span> <span class="k">range</span> <span class="k">map</span><span class="p">[</span><span class="kt">int</span><span class="p">]</span><span class="kt">string</span><span class="p">{</span>
<span class="n">posMajor</span><span class="o">:</span> <span class="s">"Major"</span><span class="p">,</span>
<span class="n">posMinor</span><span class="o">:</span> <span class="s">"Minor"</span><span class="p">,</span>
<span class="n">posPatch</span><span class="o">:</span> <span class="s">"Patch"</span><span class="p">,</span>
<span class="n">posRelFlag</span><span class="o">:</span> <span class="s">"Release Flag(s)"</span><span class="p">,</span>
<span class="p">}</span> <span class="p">{</span>
<span class="n">verVal</span> <span class="o">=</span> <span class="kt">uint8</span><span class="p">((</span><span class="n">singleValVer</span> <span class="o">&gt;&gt;</span> <span class="p">(</span><span class="m">32</span> <span class="o">-</span> <span class="p">(</span><span class="m">8</span> <span class="o">*</span> <span class="n">i</span><span class="p">)))</span> <span class="o">&amp;</span> <span class="m">0xff</span><span class="p">)</span>
<span class="n">fmt</span><span class="o">.</span><span class="n">Printf</span><span class="p">(</span><span class="s">"%s: %d (%#02x)</span><span class="se">\n</span><span class="s">"</span><span class="p">,</span> <span class="n">verNm</span><span class="p">,</span> <span class="n">verVal</span><span class="p">,</span> <span class="n">verVal</span><span class="p">)</span>
<span class="p">}</span>
<span class="c">// Prints:</span>
<span class="c">/*
Major: 1 (0x01)
Minor: 2 (0x02)
Patch: 3 (0x03)
Release Flag(s): 1 (0x01)
*/</span>
<span class="p">}</span></code></pre>
</div>
</div>
</div>
</details>
</td>
</tr>
</table>
</div>
<div class="sect5">
<h6 id="spec_msg_pfx_ver_maj"><a class="link" href="#spec_msg_pfx_ver_maj">5.1.1.1.1. Major</a></h6>
<table class="tableblock frame-all grid-all stretch">
<colgroup>
<col style="width: 25%;">
<col style="width: 75%;">
</colgroup>
<thead>
<tr>
<th class="tableblock halign-center valign-middle">Length (Octets/Bytes)</th>
<th class="tableblock halign-center valign-middle">Type</th>
</tr>
</thead>
<tbody>
<tr>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><code>1</code></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock">Unsigned 8-Bit Integer</p></td>
</tr>
</tbody>
</table>
<div class="paragraph">
<p>The <strong>Major</strong> is the first byte in <strong>Version</strong> (if interpreted as a byte slice and not a big-endian unsigned 32-bit integer).</p>
</div>
</div>
<div class="sect5">
<h6 id="spec_msg_pfx_ver_min"><a class="link" href="#spec_msg_pfx_ver_min">5.1.1.1.2. Minor</a></h6>
<table class="tableblock frame-all grid-all stretch">
<colgroup>
<col style="width: 25%;">
<col style="width: 75%;">
</colgroup>
<thead>
<tr>
<th class="tableblock halign-center valign-middle">Length (Octets/Bytes)</th>
<th class="tableblock halign-center valign-middle">Type</th>
</tr>
</thead>
<tbody>
<tr>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><code>1</code></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock">Unsigned 8-Bit Integer</p></td>
</tr>
</tbody>
</table>
<div class="paragraph">
<p>The <strong>Minor</strong> is the second byte in <strong>Version</strong> (if interpreted as a byte slice and not a big-endian unsigned 32-bit integer).</p>
</div>
</div>
<div class="sect5">
<h6 id="spec_msg_pfx_ver_patch"><a class="link" href="#spec_msg_pfx_ver_patch">5.1.1.1.3. Patch</a></h6>
<table class="tableblock frame-all grid-all stretch">
<colgroup>
<col style="width: 25%;">
<col style="width: 75%;">
</colgroup>
<thead>
<tr>
<th class="tableblock halign-center valign-middle">Length (Octets/Bytes)</th>
<th class="tableblock halign-center valign-middle">Type</th>
</tr>
</thead>
<tbody>
<tr>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><code>1</code></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock">Unsigned 8-Bit Integer</p></td>
</tr>
</tbody>
</table>
<div class="paragraph">
<p>The <strong>Patch</strong> is the third byte in <strong>Version</strong> (if interpreted as a byte slice and not a big-endian unsigned 32-bit integer).</p>
</div>
<div class="admonitionblock note">
<table>
<tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">
<div class="paragraph">
<p>The "patch" in SemVer may be more accurate to think of it as a "revision" than a "patch", but the term "revision" means something else in Semantic Version specification so "patch" is used here instead.</p>
</div>
</td>
</tr>
</table>
</div>
</div>
<div class="sect5">
<h6 id="spec_msg_pfx_ver_flags"><a class="link" href="#spec_msg_pfx_ver_flags">5.1.1.1.4. Release Flag(s)</a></h6>
<table class="tableblock frame-all grid-all stretch">
<colgroup>
<col style="width: 25%;">
<col style="width: 75%;">
</colgroup>
<thead>
<tr>
<th class="tableblock halign-center valign-middle">Length (Octets/Bytes)</th>
<th class="tableblock halign-center valign-middle">Type</th>
</tr>
</thead>
<tbody>
<tr>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><code>1</code></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock">Byte/8-Bit Length Bitmask</p></td>
</tr>
</tbody>
</table>
<div class="paragraph">
<p>The <strong>Release Flag(s)</strong> field is the fourth byte in <strong>Version</strong>. It is not intended as an unsigned 8-bit integer but rather a <a href="https://en.wikipedia.org/wiki/Mask_(computing)" target="_blank" rel="noopener">bitmasked</a> byte.</p>
</div>
<div class="paragraph">
<p>The collection of all flags is coalesced into a single byte on the wire&#8201;&#8212;&#8201;an unsigned 8-bit integer&#8201;&#8212;&#8201;with each flag occupying a single bit.</p>
</div>
<div class="paragraph">
<p>The following flags are currently defined:</p>
</div>
<table class="tableblock frame-all grid-all stretch">
<caption class="title">Table 3. AnnNet Flags</caption>
<colgroup>
<col style="width: 25%;">
<col style="width: 25%;">
<col style="width: 50%;">
</colgroup>
<thead>
<tr>
<th class="tableblock halign-center valign-middle">Integer</th>
<th class="tableblock halign-center valign-middle">Flag</th>
<th class="tableblock halign-center valign-middle">Name</th>
</tr>
</thead>
<tbody>
<tr>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><code>0</code></p></td>
<td class="tableblock halign-left valign-middle"><p class="tableblock"><code>ANET_NONE</code></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock">None; stable release.</p></td>
</tr>
<tr>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><code>1</code></p></td>
<td class="tableblock halign-left valign-middle"><p class="tableblock"><code>ANET_PREREL</code></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock">Pre-release</p></td>
</tr>
<tr>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><code>2</code></p></td>
<td class="tableblock halign-left valign-middle"><p class="tableblock"><code>ANET_UNSTABLE</code></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock">Unstable</p></td>
</tr>
<tr>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><code>4</code></p></td>
<td class="tableblock halign-left valign-middle"><p class="tableblock"><code>ANET_EXPERIMENT</code></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock">Experimental</p></td>
</tr>
</tbody>
</table>
<div class="paragraph">
<p>Additionally, several "shorthand" flags are explicitly defined by the bit-wise <code>OR</code>'d combination of other flags:</p>
</div>
<table class="tableblock frame-all grid-all stretch">
<caption class="title">Table 4. AnnNet Combined Flags</caption>
<colgroup>
<col style="width: 14.2857%;">
<col style="width: 14.2857%;">
<col style="width: 42.8571%;">
<col style="width: 28.5715%;">
</colgroup>
<thead>
<tr>
<th class="tableblock halign-center valign-middle">Integer</th>
<th class="tableblock halign-center valign-middle">Flag</th>
<th class="tableblock halign-center valign-middle">Expression</th>
<th class="tableblock halign-center valign-middle">Name</th>
</tr>
</thead>
<tbody>
<tr>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><code>3</code></p></td>
<td class="tableblock halign-left valign-middle"><p class="tableblock"><code>ANET_BETA</code></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><code>ANET_PREREL | ANET_UNSTABLE</code></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock">Beta release</p></td>
</tr>
<tr>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><code>7</code></p></td>
<td class="tableblock halign-left valign-middle"><p class="tableblock"><code>ANET_ALPHA</code></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><code>ANET_BETA | ANET_EXPERIMENT</code></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock">Alpha release</p></td>
</tr>
</tbody>
</table>
<div class="paragraph">
<p>A flag&#8217;s presence can be checked via a bit-wise <code>AND</code> against <em>flag</em> being equal to <em>flag</em>.</p>
</div>
<details>
<summary class="title">Example in Go</summary>
<div class="content">
<div class="listingblock">
<div class="title"><code>hasflag.go</code></div>
<div class="content">
<pre class="rouge highlight"><code data-lang="go"><span class="k">package</span> <span class="n">main</span>
<span class="k">import</span> <span class="p">(</span>
<span class="s">"fmt"</span>
<span class="p">)</span>
<span class="k">const</span> <span class="n">anetNone</span> <span class="kt">uint8</span> <span class="o">=</span> <span class="m">0</span>
<span class="k">const</span> <span class="p">(</span>
<span class="n">anetPreRel</span> <span class="kt">uint8</span> <span class="o">=</span> <span class="m">1</span> <span class="o">&lt;&lt;</span> <span class="no">iota</span>
<span class="n">anetUnstable</span>
<span class="n">anetExperiment</span>
<span class="n">anetBeta</span> <span class="o">=</span> <span class="n">anetPreRel</span> <span class="o">|</span> <span class="n">anetUnstable</span>
<span class="n">anetAlpha</span> <span class="o">=</span> <span class="n">anetBeta</span> <span class="o">|</span> <span class="n">anetExperiment</span>
<span class="p">)</span>
<span class="k">var</span> <span class="p">(</span>
<span class="c">// In Golang, a byte is exactly equivalent to a uint8.</span>
<span class="c">// Use the same value extracted in the example `extractversion.go`.</span>
<span class="c">// A value of 0x01 (1) indicates Pre-Release flag is set, with no other myFlags set.</span>
<span class="n">myFlags</span> <span class="kt">byte</span> <span class="o">=</span> <span class="m">0x01</span>
<span class="p">)</span>
<span class="k">func</span> <span class="n">main</span><span class="p">()</span> <span class="p">{</span>
<span class="n">fmt</span><span class="o">.</span><span class="n">Printf</span><span class="p">(</span><span class="s">"Flags:</span><span class="se">\t</span><span class="s">%d</span><span class="se">\t</span><span class="s">%#02x</span><span class="se">\n\n</span><span class="s">"</span><span class="p">,</span> <span class="n">myFlags</span><span class="p">,</span> <span class="n">myFlags</span><span class="p">)</span>
<span class="c">// Prints:</span>
<span class="c">/*
Flags: 1 0x01
*/</span>
<span class="k">for</span> <span class="n">flag</span><span class="p">,</span> <span class="n">flagNm</span> <span class="o">:=</span> <span class="k">range</span> <span class="k">map</span><span class="p">[</span><span class="kt">uint8</span><span class="p">]</span><span class="kt">string</span><span class="p">{</span>
<span class="n">anetPreRel</span><span class="o">:</span> <span class="s">"Pre-release"</span><span class="p">,</span>
<span class="n">anetUnstable</span><span class="o">:</span> <span class="s">"Unstable"</span><span class="p">,</span>
<span class="n">anetExperiment</span><span class="o">:</span> <span class="s">"Experimental"</span><span class="p">,</span>
<span class="n">anetBeta</span><span class="o">:</span> <span class="s">"Beta release"</span><span class="p">,</span>
<span class="n">anetAlpha</span><span class="o">:</span> <span class="s">"Alpha release"</span><span class="p">,</span>
<span class="p">}</span> <span class="p">{</span>
<span class="n">fmt</span><span class="o">.</span><span class="n">Printf</span><span class="p">(</span>
<span class="s">"Has flag '%s' (%d, %#02x):</span><span class="se">\t</span><span class="s">%v</span><span class="se">\n\n</span><span class="s">"</span><span class="p">,</span>
<span class="n">flagNm</span><span class="p">,</span> <span class="n">flag</span><span class="p">,</span> <span class="n">flag</span><span class="p">,</span> <span class="n">myFlags</span><span class="o">&amp;</span><span class="n">flag</span> <span class="o">==</span> <span class="n">flag</span><span class="p">,</span>
<span class="p">)</span>
<span class="p">}</span>
<span class="c">// Prints:</span>
<span class="c">/*
Flags: 1 0x01
Has flag 'Pre-release' (1, 0x01): true
Has flag 'Unstable' (2, 0x02): false
Has flag 'Experimental' (4, 0x04): false
Has flag 'Beta release' (3, 0x03): false
Has flag 'Alpha release' (7, 0x07): false
*/</span>
<span class="p">}</span></code></pre>
</div>
</div>
</div>
</details>
</div>
</div>
<div class="sect4">
<h5 id="spec_msg_pfx_len"><a class="link" href="#spec_msg_pfx_len">5.1.1.2. Payload Length</a></h5>
<table class="tableblock frame-all grid-all stretch">
<colgroup>
<col style="width: 25%;">
<col style="width: 75%;">
</colgroup>
<thead>
<tr>
<th class="tableblock halign-center valign-middle">Length (Octets/Bytes)</th>
<th class="tableblock halign-center valign-middle">Type</th>
</tr>
</thead>
<tbody>
<tr>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><code>4</code></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock">Big-Endian Unsigned 32-Bit Integer</p></td>
</tr>
</tbody>
</table>
<div class="paragraph">
<p>The <strong>Payload Length</strong> indicates the length of the <a href="#spec_msg_payload">Payload</a>, which is the arbitrary/implementation-specific data that follows the <a href="#spec_msg_pfx">Standard Prefix</a> (and thus the Payload Length is the last field in the Prefix).</p>
</div>
<div class="paragraph">
<p>It <strong>must</strong> be the length of the entirety of the payload that follows (but <strong>not</strong> including the size of the Prefix).</p>
</div>
<div class="admonitionblock note">
<table>
<tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">
<div class="paragraph">
<p><code>0</code> is a valid Payload Length, as is an empty <a href="#spec_msg_payload">Payload</a>. However, if Payload Length is specified as <code>0</code> but there <strong>is</strong> Payload data, that data must be considered <strong>invalid</strong> by listening implementations and <em>should not</em> be read/<em>should be</em> discarded (with the exception of <strong>validation, testing, or abuse mitigation purposes</strong>).</p>
</div>
</td>
</tr>
</table>
</div>
</div>
</div>
<div class="sect3">
<h4 id="spec_msg_payload"><a class="link" href="#spec_msg_payload">5.1.2. Payload</a></h4>
<div class="paragraph">
<p>The <strong>Payload</strong> is the arbitrary data that follows the <a href="#spec_msg_pfx">Standard Prefix</a> in the <a href="#spec_msg">AnnNet Message Format</a>.</p>
</div>
<div class="paragraph">
<p>It is an arbitrary length (specified/bounded by <a href="#spec_msg_pfx_len">Payload Length</a>) of payload data.</p>
</div>
</div>
</div>
<div class="sect2">
<h3 id="spec_link"><a class="link" href="#spec_link">5.2. AnnNet Link</a></h3>
<div class="paragraph">
<p><strong>AnnNet Link</strong> operates on OSI layer 2 as an <a href="https://en.wikipedia.org/wiki/EtherType" target="_blank" rel="noopener">EtherType</a> protocol.</p>
</div>
<div class="admonitionblock warning">
<table>
<tr>
<td class="icon">
<div class="title">Warning</div>
</td>
<td class="content">
<div class="paragraph">
<p>For obvious reasons, this is not going to play well with other EtherTypes (e.g. VLAN/802.1Q tagging).</p>
</div>
<div class="paragraph">
<p>Future versions of AnnNet may implement VLAN support.</p>
</div>
<div class="paragraph">
<p>If VLAN support is added, it will be done so in a dedicated major release.</p>
</div>
</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>It <em>may</em> send to either a directed MAC/physical address of a host <strong>or</strong> to the broadcast MAC/PHY<em>(sical)</em> address <code>ff:ff:ff:ff:ff:ff</code>.
Its source <em>must</em> be the MAC/PHYS address of the network interface it is sending from.</p>
</div>
<div class="paragraph">
<p>It <strong>must not</strong> traverse physical network boundaries (can&#8217;t, really, since it&#8217;s layer 2).</p>
</div>
<div class="paragraph">
<p>It currently uses the <code>0x88b5</code> EtherType by default, as AnnNet is still in experimental stages and this EtherType is <a href="https://standards-oui.ieee.org/ethertype/eth.txt" target="_blank" rel="noopener">reserved for prototyping</a> per IEEE Std 802. (<code>0x88b6</code> is another viable option for your implementation, as it too is reserved by IEEE Std 802 for prototyping.) See also <a href="https://www.iana.org/assignments/ieee-802-numbers/ieee-802-numbers.xhtml#ieee-802-numbers-1" target="_blank" rel="noopener">IANA&#8217;s registration list</a>.</p>
</div>
<div class="paragraph">
<p>If AnnNet is allocated a dedicated IEEE/IANA-registered EtherType, it will be implemented in a new major version release.</p>
</div>
<div class="paragraph">
<p>The <a href="#spec_msg">AnnNet Message</a> follows the EtherType value immediately:</p>
</div>
<table class="tableblock frame-all grid-all stretch">
<caption class="title">Table 5. AnnNet Link Packet</caption>
<colgroup>
<col style="width: 20%;">
<col style="width: 20%;">
<col style="width: 20%;">
<col style="width: 40%;">
</colgroup>
<tbody>
<tr>
<td class="tableblock halign-center valign-middle" colspan="3"><p class="tableblock"><strong>Ethernet II Header (14 Bytes)</strong></p></td>
<td class="tableblock halign-center valign-middle"></td>
</tr>
<tr>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong>E:D</strong></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong>E:S</strong></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong>E:T</strong></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong><a href="#spec_msg">AnnNet Message</a></strong></p></td>
</tr>
</tbody>
</table>
<div class="paragraph">
<p>Where:</p>
</div>
<div class="dlist">
<dl>
<dt class="hdlist1">E:D</dt>
<dd>
<p>Destination MAC/PHY<em>(sical)</em> Address <em>(6 Bytes)</em></p>
</dd>
<dt class="hdlist1">E:S</dt>
<dd>
<p>Source MAC/PHY<em>(sical)</em> Address <em>(6 Bytes)</em></p>
</dd>
<dt class="hdlist1">E:T</dt>
<dd>
<p>EtherType (<code>0x88b5</code> or <code>0x88b6</code>) <em>(2 Bytes)</em></p>
</dd>
</dl>
</div>
</div>
<div class="sect2">
<h3 id="spec_bcast"><a class="link" href="#spec_bcast">5.3. AnnNet Broadcast</a></h3>
<div class="paragraph">
<p>AnnNet Broadcast operates on layer 3, making use of <a href="#spec_bcast_v4">IPv4</a> (EtherType <code>0x0800</code>) and/or <a href="#spec_bcast_v6">IPv6</a> (EtherType <code>0x86dd</code>).</p>
</div>
<div class="sect3">
<h4 id="spec_bcast_v4"><a class="link" href="#spec_bcast_v4">5.3.1. IPv4</a></h4>
<div class="paragraph">
<p>If IPv4, the AnnNet Broadcast sender <em>may</em> send to:</p>
</div>
<div class="ulist">
<ul>
<li>
<p>The IPv4 limited broadcast address <code>255.255.255.255/32</code> (RFC <a href="https://datatracker.ietf.org/doc/html/rfc6890#section-2.2.2" target="_blank" rel="noopener">6890 § 2.2.2</a>, <a href="https://datatracker.ietf.org/doc/html/rfc8190#section-2.2" target="_blank" rel="noopener">8190 § 2.2</a>)</p>
</li>
<li>
<p>Or a direct address of a host, IPv4 link-local (also known as <em>Automatic Private IP Addressing/APIPA</em>, <a href="https://datatracker.ietf.org/doc/html/rfc3927" target="_blank" rel="noopener">RFC 3927</a>) or not.</p>
<div class="ulist">
<ul>
<li>
<p>The target host/network <strong>must</strong> not traverse organization boundary (e.g. <strong>must not</strong> be routed directly across the Internet).</p>
</li>
</ul>
</div>
</li>
</ul>
</div>
<div class="paragraph">
<p>If using the <code>255.255.255.255/32</code> broadcast address, the source address <strong>must</strong> be a network-reachable address of the interface the message is sending from.</p>
</div>
<div class="paragraph">
<p>If using any other address, the source address <strong>must</strong> be an address reachable by the network/host the message is being sent to.</p>
</div>
<div class="sect4">
<h5 id="spec_bcast_v4_msg"><a class="link" href="#spec_bcast_v4_msg">5.3.1.1. Message Format</a></h5>
<div class="paragraph">
<p>The <a href="#spec_msg">AnnNet Message</a> follows the Options value immediately:</p>
</div>
<table class="tableblock frame-all grid-all stretch">
<caption class="title">Table 6. AnnNet Broadcast Packet, IPv4</caption>
<colgroup>
<col style="width: 5.2631%;">
<col style="width: 5.2631%;">
<col style="width: 5.2631%;">
<col style="width: 5.2631%;">
<col style="width: 5.2631%;">
<col style="width: 5.2631%;">
<col style="width: 5.2631%;">
<col style="width: 5.2631%;">
<col style="width: 5.2631%;">
<col style="width: 5.2631%;">
<col style="width: 5.2631%;">
<col style="width: 5.2631%;">
<col style="width: 5.2631%;">
<col style="width: 5.2631%;">
<col style="width: 5.2631%;">
<col style="width: 5.2631%;">
<col style="width: 5.2631%;">
<col style="width: 10.5273%;">
</colgroup>
<tbody>
<tr>
<td class="tableblock halign-center valign-middle" colspan="3"><p class="tableblock"><strong>Ethernet II Header<br>
(&gt;= 14 Bytes)</strong></p></td>
<td class="tableblock halign-center valign-middle" colspan="14"><p class="tableblock"><strong>IP Header (20-60 Bytes)</strong></p></td>
<td class="tableblock halign-center valign-middle"></td>
</tr>
<tr>
<td class="tableblock halign-center valign-middle" colspan="3"></td>
<td class="tableblock halign-center valign-middle" colspan="2"><p class="tableblock"><strong>V/IHL<br>
(1 Byte)</strong></p></td>
<td class="tableblock halign-center valign-middle" colspan="2"><p class="tableblock"><strong>D/E<br>
(1 Byte)</strong></p></td>
<td class="tableblock halign-center valign-middle"></td>
<td class="tableblock halign-center valign-middle"></td>
<td class="tableblock halign-center valign-middle" colspan="2"><p class="tableblock"><strong>Fragmentation<br>
(1 Byte)</strong></p></td>
<td class="tableblock halign-center valign-middle"></td>
<td class="tableblock halign-center valign-middle"></td>
<td class="tableblock halign-center valign-middle"></td>
<td class="tableblock halign-center valign-middle"></td>
<td class="tableblock halign-center valign-middle"></td>
<td class="tableblock halign-center valign-middle"></td>
<td class="tableblock halign-center valign-middle"></td>
</tr>
<tr>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong>E:D</strong></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong>E:S</strong></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong>E:T</strong></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong>VI:V</strong></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong>VI:I</strong></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong>DE:D</strong></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong>DE:E</strong></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong>IP:L</strong></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong>IP:I</strong></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong>IP:F</strong></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong>IP:R</strong></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong>IP:T</strong></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong>IP:P</strong></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong>IP:C</strong></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong>IP:S</strong></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong>IP:D</strong></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong>IP:O</strong></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong><a href="#spec_msg">AnnNet Message</a></strong></p></td>
</tr>
</tbody>
</table>
<div class="paragraph">
<p>Where:</p>
</div>
<div class="dlist">
<dl>
<dt class="hdlist1">E:D</dt>
<dd>
<p>Destination MAC/PHY<em>(sical)</em> Address <em>(6 Bytes)</em></p>
</dd>
<dt class="hdlist1">E:S</dt>
<dd>
<p>Source MAC/PHY<em>(sical)</em> Address <em>(6 Bytes)</em></p>
</dd>
<dt class="hdlist1">E:T</dt>
<dd>
<p>EtherType (<code>0x86dd</code>) <em>(&gt;= 2 Bytes; may be prefixed with VLAN information etc.)</em></p>
</dd>
<dt class="hdlist1">VI:V</dt>
<dd>
<p>Version <em>(4 Bits; see <a href="#xtra_bitpacked_vihl">Addendum</a>)</em></p>
</dd>
<dt class="hdlist1">VI:I</dt>
<dd>
<p>Internet Header Length <em>(4 Bits; see <a href="#xtra_bitpacked_vihl">Addendum</a>)</em></p>
</dd>
<dt class="hdlist1">DE:D</dt>
<dd>
<p>DSCP (Differentiated Services Code Point; QoS/traffic class) <em>(6 Bits; see <a href="#xtra_bitpacked_de">Addendum</a>)</em></p>
</dd>
<dt class="hdlist1">DE:E</dt>
<dd>
<p>ECN (Explicit Congestion Notification) <em>(2 Bits; see <a href="#xtra_bitpacked_de">Addendum</a>)</em></p>
</dd>
<dt class="hdlist1">IP:L</dt>
<dd>
<p>Total size of IP header + payload (not to be confused with <a href="#spec_msg_pfx_len">Payload Length</a>) <em>(2 Bytes)</em></p>
</dd>
<dt class="hdlist1">IP:I</dt>
<dd>
<p>Identification (used in fragmentation) <em>(2 Bytes)</em></p>
</dd>
<dt class="hdlist1">IP:F</dt>
<dd>
<p>IP Flags <em>(3 bits; see <a href="#xtra_bitpacked_frag">Addendum</a>)</em></p>
</dd>
<dt class="hdlist1">IP:R</dt>
<dd>
<p>Fragmentation Offset <em>(13 Bits; see <a href="#xtra_bitpacked_frag">Addendum</a>)</em></p>
</dd>
<dt class="hdlist1">IP:T</dt>
<dd>
<p>TTL <em>(1 Byte)</em></p>
</dd>
<dt class="hdlist1">IP:P</dt>
<dd>
<p><a href="#spec_bcast_protonum">IP/Transport Protocol Number</a> <em>(1 Byte)</em></p>
</dd>
<dt class="hdlist1">IP:C</dt>
<dd>
<p>Header Checksum (RFC <a href="https://datatracker.ietf.org/doc/html/rfc1071" target="_blank" rel="noopener">1071</a>, <a href="https://datatracker.ietf.org/doc/html/rfc1071" target="_blank" rel="noopener">1141</a>, <a href="https://datatracker.ietf.org/doc/html/rfc1624" target="_blank" rel="noopener">1624</a>) <em>(2 Bytes)</em></p>
</dd>
<dt class="hdlist1">IP:S</dt>
<dd>
<p>Source IPv4 Address <em>(32 Bits/4 Bytes)</em></p>
</dd>
<dt class="hdlist1">IP:D</dt>
<dd>
<p>Destination IPv4 Address <em>(32 Bits/4 Bytes)</em></p>
</dd>
<dt class="hdlist1">IP:O</dt>
<dd>
<p>Options (Optional) (See the <a href="https://www.iana.org/assignments/ip-parameters/ip-parameters.xhtml" target="_blank" rel="noopener">IANA Registered IP Parameters</a> for details) <em>(Variable Length)</em></p>
</dd>
</dl>
</div>
</div>
</div>
<div class="sect3">
<h4 id="spec_bcast_v6"><a class="link" href="#spec_bcast_v6">5.3.2. IPv6</a></h4>
<div class="paragraph">
<p>If IPv6, the AnnNet Broadcast sender <em>may</em> send to:</p>
</div>
<div class="ulist">
<ul>
<li>
<p>The multicast addresses (<code>ff0<em>x</em></code>) with the following scopes (<code>scop</code>) (RFC <a href="https://datatracker.ietf.org/doc/html/rfc3513#section-2.7" target="_blank" rel="noopener">3513 § 2.7</a>, <a href="https://datatracker.ietf.org/doc/html/rfc4291#section-2.7" target="_blank" rel="noopener">4291 § 2.7</a>, <a href="https://datatracker.ietf.org/doc/html/rfc7346#section-2">7346 § 2</a>, see also <a href="https://www.iana.org/assignments/ipv6-multicast-addresses/ipv6-multicast-addresses.xhtml" target="_blank" rel="noopener">IANA IPv6 Multicast Registry</a>)</p>
<div class="ulist">
<ul>
<li>
<p><strong>except</strong> as reserved by other IANA/IETF/IESG-recognized protocols (i.e. <code>OSPFIGP</code>, <code>NDP</code>, et. al.):</p>
<div class="ulist">
<ul>
<li>
<p>Scope <code>1</code> (<code>0x0001</code>), <em>Interface-Local</em></p>
</li>
<li>
<p>Scope <code>2</code> (<code>0x0002</code>), <em>Link-Local</em></p>
</li>
<li>
<p>Scope <code>4</code> (<code>0x0004</code>), <em>Admin-Local</em></p>
</li>
<li>
<p>Scope <code>5</code> (<code>0x0005</code>), <em>Site-Local</em></p>
</li>
<li>
<p>Scope <code>8</code> (<code>0x0008</code>), <em>Organization-Local</em></p>
</li>
</ul>
</div>
</li>
<li>
<p>A generally safe address would be <code>ff02::1</code> (<em>All Nodes, Link-Local</em>) but refer to <a href="https://www.iana.org/assignments/ipv6-multicast-addresses/ipv6-multicast-addresses.xhtml" target="_blank" rel="noopener">the IANA registry</a> to select the most appropriate multicast address(es).</p>
</li>
</ul>
</div>
</li>
<li>
<p>Or a direct IPv6 Link-Local Address (LLA) of a host (RFC <a href="https://datatracker.ietf.org/doc/html/rfc3513#section-2.5.6" target="_blank" rel="noopener">3513 § 2.5.6</a>, <a href="https://datatracker.ietf.org/doc/html/rfc3927" target="_blank" rel="noopener">3927</a>, <a href="https://datatracker.ietf.org/doc/html/rfc4291#section-2.5.6" target="_blank" rel="noopener">4291 § 2.5.6</a>, <a href="https://datatracker.ietf.org/doc/html/rfc7404" target="_blank" rel="noopener">7404</a> <em>(tangentially)</em>)</p>
</li>
<li>
<p>Or a direct IPv6 Unique Local Address (ULA) of a host (<a href="https://datatracker.ietf.org/doc/html/rfc4193" target="_blank" rel="noopener">RFC 4193</a>)</p>
</li>
</ul>
</div>
<div class="paragraph">
<p>If using a multicast address, the source address <strong>must</strong> be a network-reachable address of the interface the message is sending from.</p>
</div>
<div class="paragraph">
<p>If using any other address, the source address <strong>must</strong> be an address reachable by the network/host the message is being sent to.</p>
</div>
<div class="sect4">
<h5 id="spec_bcast_v6_msg"><a class="link" href="#spec_bcast_v6_msg">5.3.2.1. Message Format</a></h5>
<div class="paragraph">
<p>The <a href="#spec_msg">AnnNet Message</a> follows the Destination Address value immediately:</p>
</div>
<table class="tableblock frame-all grid-all stretch">
<caption class="title">Table 7. AnnNet Broadcast Packet, IPv6</caption>
<colgroup>
<col style="width: 7.6923%;">
<col style="width: 7.6923%;">
<col style="width: 7.6923%;">
<col style="width: 7.6923%;">
<col style="width: 7.6923%;">
<col style="width: 7.6923%;">
<col style="width: 7.6923%;">
<col style="width: 7.6923%;">
<col style="width: 7.6923%;">
<col style="width: 7.6923%;">
<col style="width: 7.6923%;">
<col style="width: 15.3847%;">
</colgroup>
<tbody>
<tr>
<td class="tableblock halign-center valign-middle" colspan="3"><p class="tableblock"><strong>Ethernet II Header<br>
(&gt;= 14 Bytes)</strong></p></td>
<td class="tableblock halign-center valign-middle" colspan="8"><p class="tableblock"><strong>IP Header (40 Bytes)</strong></p></td>
<td class="tableblock halign-center valign-middle"></td>
</tr>
<tr>
<td class="tableblock halign-center valign-middle" colspan="3"></td>
<td class="tableblock halign-center valign-middle" colspan="3"><p class="tableblock"><strong>V/TC/Flow (4 Bytes)</strong></p></td>
<td class="tableblock halign-center valign-middle" colspan="6"></td>
</tr>
<tr>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong>E:D</strong></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong>E:S</strong></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong>E:T</strong></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong>VTF:V</strong></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong>VTF:T</strong></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong>VTF:F</strong></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong>IP:L</strong></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong>IP:N</strong></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong>IP:H</strong></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong>IP:S</strong></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong>IP:D</strong></p></td>
<td class="tableblock halign-center valign-middle"><p class="tableblock"><strong><a href="#spec_msg">AnnNet Message</a></strong></p></td>
</tr>
</tbody>
</table>
<div class="paragraph">
<p>Where:</p>
</div>
<div class="dlist">
<dl>
<dt class="hdlist1">E:D</dt>
<dd>
<p>Destination MAC/PHY<em>(sical)</em> Address <em>(6 Bytes)</em></p>
</dd>
<dt class="hdlist1">E:S</dt>
<dd>
<p>Source MAC/PHY<em>(sical)</em> Address <em>(6 Bytes)</em></p>
</dd>
<dt class="hdlist1">E:T</dt>
<dd>
<p>EtherType (<code>0x86dd</code>) <em>(&gt;= 2 Bytes; may be prefixed with VLAN information etc.)</em></p>
</dd>
<dt class="hdlist1">VTF:V</dt>
<dd>
<p>Version <em>(4 Bits; see <a href="#xtra_bitpacked_vtf">Addendum</a>)</em></p>
</dd>
<dt class="hdlist1">VTF:T</dt>
<dd>
<p>Traffic Class <em>(8 Bits)</em> <em>(<strong>not</strong> 1 Byte; see <a href="#xtra_bitpacked_vtf">Addendum</a>)</em></p>
</dd>
<dt class="hdlist1">VTF:F</dt>
<dd>
<p>Flow Label <em>(20 bits; see <a href="#xtra_bitpacked">Addendum</a>)</em></p>
</dd>
<dt class="hdlist1">IP:L</dt>
<dd>
<p>IP Payload Length (not to be confused with <a href="#spec_msg_pfx_len">Payload Length</a>) <em>(2 Bytes)</em></p>
</dd>
<dt class="hdlist1">IP:N</dt>
<dd>
<p><a href="#spec_bcast_protonum">Next Header</a> (transport protocol number) <em>(1 Byte)</em></p>
</dd>
<dt class="hdlist1">IP:H</dt>
<dd>
<p>Hop Limit <em>(1 Byte)</em></p>
</dd>
<dt class="hdlist1">IP:S</dt>
<dd>
<p>Source IPv6 Address <em>(128 Bits/16 Bytes)</em></p>
</dd>
<dt class="hdlist1">IP:D</dt>
<dd>
<p>Destination IPv6 Address <em>(128 Bits/16 Bytes)</em></p>
</dd>
</dl>
</div>
</div>
</div>
<div class="sect3">
<h4 id="spec_bcast_protonum"><a class="link" href="#spec_bcast_protonum">5.3.3. Internet Protocol Number</a></h4>
<div class="paragraph">
<p>AnnNet currently uses the <em>IPv4 protocol</em>/<em>IPv6 Next Header</em> protocol number <code>253</code> (<code>0xfd</code>) by default, as AnnNet is still in experimental stages and this protocol is <a href="https://www.iana.org/assignments/protocol-numbers/protocol-numbers.xhtml" target="_blank" rel="noopener">reserved for experimentation</a> per IANA. (<code>254</code>, <code>0xfe</code>, is another viable option for your implementation as it too is reserved by IANA for experimentation.)</p>
</div>
<div class="paragraph">
<p>If AnnNet is allocated a dedicated IANA-registered Protocol/Next Header, it will be implemented in a new major version release.</p>
</div>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="limits"><a class="link" href="#limits">6. Limitations</a></h2>
<div class="sectionbody">
<div class="olist arabic">
<ol class="arabic">
<li>
<p>AnnNet messages <strong>must</strong> fit into a single frame on the network it is being sent/received on. If message continuation or longer messages are wanted/desired, then it is up to the implementer to add a mechanism for this within their implementation&#8217;s payload.</p>
<div class="olist loweralpha">
<ol class="loweralpha" type="a">
<li>
<p>Likewise for checksumming; while most NICs will automatically handle the standard CRC32 <a href="https://en.wikipedia.org/wiki/Frame_check_sequence" target="_blank" rel="noopener">Frame Check Sequence</a> at the end of the entire frame (AnnNet Link is still Ethernet II), if you require checksumming within your application for <strong>payloads</strong> it must be accounted for by your application. If you are using hardware that doesn&#8217;t automatically append/strip the FCS, your application must also account for that as well.</p>
</li>
<li>
<p>For AnnNet Broadcast over IPv4, ensure that you are including the 16-bit <a href="https://en.wikipedia.org/wiki/Internet_checksum" target="_blank" rel="noopener">"Internet checksum"</a> of the header (see RFCs <a href="https://datatracker.ietf.org/doc/html/rfc1071" target="_blank" rel="noopener">1071</a>, <a href="https://datatracker.ietf.org/doc/html/rfc1141" target="_blank" rel="noopener">1141</a>, and <a href="https://datatracker.ietf.org/doc/html/rfc1624" target="_blank" rel="noopener">1624</a>).<br>
Most kernels can/will automatically insert this (e.g. on Linux, with <code>IPPROTO_RAW</code>/raw sockets with the <code>IP_HDRINCL</code> option, see <a href="https://man7.org/linux/man-pages/man7/raw.7.html" target="_blank" rel="noopener"><code>raw(7)</code></a>), but if your implementation doesn&#8217;t/can&#8217;t use such a mechanism then you must do so yourself.<br>
IPv6 does not require a header checksum.</p>
</li>
</ol>
</div>
</li>
</ol>
</div>
</div>
</div>
<div class="sect1">
<h2 id="fq"><a class="link" href="#fq">7. (F)AQ/FUQ (Anticipated, Frequently Asked/Anticipated/Unasked Questions)</a></h2>
<div class="sectionbody">
<div class="sect2">
<h3 id="fq_tcpip"><a class="link" href="#fq_tcpip">7.1. Why do you reference the OSI model instead of the TCP/IP model? It&#8217;s old/outdated/inaccurate.</a></h3>
<div class="paragraph">
<p>Hold onto your seat.</p>
</div>
<div class="paragraph">
<p>Several reasons:</p>
</div>
<div class="olist arabic">
<ol class="arabic">
<li>
<p>The OSI model is standardized. There is only a <strong>single</strong>, <strong>canonical</strong>, <strong>authoritative</strong> "OSI model" when it comes to network models.</p>
<div class="paragraph">
<p>References are unambiguous. Boundaries between layers and their definitions are <strong>mostly</strong> clear. (And the ISO/IEC provides supplementals for any ambiguities that arise over the years.)</p>
</div>
<div class="paragraph">
<p>As for "the TCP/IP model", <a href="https://en.wikipedia.org/wiki/Internet_protocol_suite#Layering_evolution_and_representations_in_the_literature" target="_blank" rel="noopener">which one are you referring to</a>?</p>
</div>
<div class="paragraph">
<p>There&#8217;s no less than <strong>seven different models</strong> that are referred to as "<em><strong>the</strong> TCP/IP model</em>". (The linked-to article doesn&#8217;t even mention e.g. the DoD model.) And they&#8217;re all different in ways enough to make this confusing.</p>
</div>
</li>
<li>
<p>The OSI model is more nuanced and detailed.</p>
<div class="paragraph">
<p>When one is talking about <strong>IP protocols</strong> and <strong>service protocols</strong> in the <em>same context</em>, things get very confusing very quickly. One can say "protocol" and it can apply to either ambiguously.</p>
</div>
<div class="paragraph">
<p>If instead one says "L2 protocol" or "layer 2 protocol" it&#8217;s immediately clear that it operates without (IP) addressing, or "L3 protocol"/"layer 3 protocol" and it&#8217;s immediately clear that a protocol that DOES use (IP) addressing is being referenced.</p>
</div>
</li>
</ol>
</div>
</div>
<div class="sect2">
<h3 id="fq_proto"><a class="link" href="#fq_proto">7.2. Why Shouldn&#8217;t I Use AnnNet for Regular Traffic?</a></h3>
<div class="paragraph">
<p>On a purely technical level, there&#8217;s nothing <strong>stopping</strong> you from doing so (aside from MTU windows, so you&#8217;d need to find some way of implementing message continuation, ordering, checksumming, etc.&#8201;&#8212;&#8201;at that point, just use UDP multicast or something else).</p>
</div>
<div class="paragraph">
<p>But AnnNet is designed to be a lightweight announcement protocol for a <em>local</em> (i.e. within the same subnet/link system) network.</p>
</div>
<div class="paragraph">
<p>It is designed to act like e.g.:</p>
</div>
<div class="ulist">
<ul>
<li>
<p><a href="https://datatracker.ietf.org/doc/html/rfc826" target="_blank" rel="noopener"><em>An Ethernet Address Resolution Protocol &#8230;&#8203;</em></a> (<code>ARP</code>)</p>
</li>
<li>
<p><a href="https://datatracker.ietf.org/doc/html/rfc4861" target="_blank" rel="noopener"><em>Neighbor Discovery for IP version 6 (IPv6)</em></a> (<code>ND</code>)</p>
</li>
<li>
<p>Lease requests for:</p>
<div class="ulist">
<ul>
<li>
<p><a href="https://datatracker.ietf.org/doc/html/rfc2131" target="_blank" rel="noopener"><em>Dynamic Host Configuration Protocol</em></a> (<code>DHCP</code>)</p>
</li>
<li>
<p><a href="https://datatracker.ietf.org/doc/html/rfc8415" target="_blank" rel="noopener"><em>Dynamic Host Configuration Protocol for IPv6</em> (<code>DHCPv6</code>)</a></p>
</li>
</ul>
</div>
</li>
</ul>
</div>
<div class="paragraph">
<p>etc., but with (very small amounts of) <strong>arbitrary data</strong> making it "plug-and-play" with &gt;= L3 protocols/services' configuration.</p>
</div>
<div class="paragraph">
<p>It explicitly avoids defining any formation of payloads, message format, or the like&#8201;&#8212;&#8201;because it is designed to be entirely agnostic of whatever use case it is implemented for.</p>
</div>
<div class="paragraph">
<p>However, AnnNet <strong>strongly encourages</strong> the use of <a href="https://wireproto.io/" target="_blank" rel="noopener">WireProto</a> for payload packing due to its minimal overhead, its strong hierarchical structuring, and its flexibility.</p>
</div>
<div class="admonitionblock warning">
<table>
<tr>
<td class="icon">
<div class="title">Warning</div>
</td>
<td class="content">
<div class="paragraph">
<p>Future versions of AnnNet <strong>may <em>require</em></strong> use of WireProto (but WireProto itself is a very loose and flexible format, and would not add much overhead).</p>
</div>
<div class="paragraph">
<p>If this requirement is put in place, it will be in its own major revision.</p>
</div>
</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>If one needs a much more robust solution for anything <strong>beyond</strong> e.g. announcement messages, <a href="https://nats.io/" target="_blank" rel="noopener">NATS</a> may be useful for actual messaging between <strong>known</strong> members. (AnnNet would then be used in this case to provide a mechanism for <em>making members known/discovered</em> with no explicit configuration.)<br></p>
</div>
<div class="admonitionblock note">
<table>
<tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">
<div class="paragraph">
<p>NATS also does not define any sort of payload format in its <strong>encapsulated</strong> payloads; most implementations tend to use <a href="https://protobuf.dev/" target="_blank" rel="noopener">ProtoBuf/Protocol Buffers</a>, <a href="https://msgpack.org/index.html" target="_blank" rel="noopener">MessagePack</a>, JSON, or the like.</p>
</div>
</td>
</tr>
</table>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="xtra"><a class="link" href="#xtra">8. Addendum/Errata/Administrivia</a></h2>
<div class="sectionbody">
<div class="sect2">
<h3 id="xtra_bitpacked"><a class="link" href="#xtra_bitpacked">8.1. Bitpacked Fields</a></h3>
<div class="paragraph">
<p>Certain fields in IP headers are less than 1 byte or don&#8217;t align to a clean byte boundary on their own, and therefore generally require bitwise operations to read/encapsulate meaningful values within them.</p>
</div>
<div class="sect3">
<h4 id="xtra_bitpacked_vihl"><a class="link" href="#xtra_bitpacked_vihl">8.1.1. IP Version, IHL (IPv4)</a></h4>
<div class="paragraph">
<p>The IP version and IHL combined make up a single byte, with four-byte "nibbles" each.</p>
</div>
<div class="admonitionblock note">
<table>
<tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">
<div class="paragraph">
<p>The IHL is calculated as the number of "32-bit words" in the IP header.</p>
</div>
<div class="paragraph">
<p>In other words, <code>IHL = (B * 8) / 32</code> (where <code>B</code> is the size of the IP header&#8201;&#8212;&#8201;everything from "VI:V" to "IP:O" inclusive in <a href="#spec_bcast_v4_msg">Message Format</a>&#8201;&#8212;&#8201;in <strong>bytes</strong>).</p>
</div>
<div class="paragraph">
<p>Or, alternatively, <code>IHL = b / 32</code> (where <code>b</code> is the size of the IP header&#8201;&#8212;&#8201;everything from "VI:V" to "IP:O" inclusive in <a href="#spec_bcast_v4_msg">Message Format</a>&#8201;&#8212;&#8201;in <strong>bits</strong>).</p>
</div>
<div class="paragraph">
<p>Since the V/IHL is a fixed size, this does <strong>not</strong> cause a recursion/chicken-egg problem.</p>
</div>
</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>To <strong>create</strong> the Version/IHL value, the Version (<strong>always</strong> <code>4</code> because IPv4) is packed as a big-endian 8-bit unsigned integer, and is then bit-shifted to the left by 4 bits and bitwise-<code>OR</code>'d with the IHL (as a big-endian 8-bit unsigned integer bitwise-<code>AND</code>-masked to the lower bits via <code>0x0f</code>/<code>15</code>).</p>
</div>
<div class="paragraph">
<p>To <strong>retrieve</strong> the Version and IHL, the value is bit-shifted to the <strong>right</strong> by 4 bits and cast as an 8-bit unsigned integer (this is the Version, <code>4</code>), and the original value is also bitwise-<code>AND</code>'d with the lower bits via <code>0x0f</code> (<code>15</code>) and cast as an unsigned 8-bit integer to get the IHL.</p>
</div>
<details>
<summary class="title">Example in Go</summary>
<div class="content">
<div class="listingblock">
<div class="content">
<pre class="rouge highlight"><code data-lang="go"><span class="k">package</span> <span class="n">main</span>
<span class="k">import</span> <span class="p">(</span>
<span class="s">`fmt`</span>
<span class="s">`log`</span>
<span class="s">"strconv"</span>
<span class="p">)</span>
<span class="k">const</span> <span class="p">(</span>
<span class="n">vihlBits</span> <span class="kt">string</span> <span class="o">=</span> <span class="s">"01000101"</span> <span class="c">// [0100 0101], or 69 (0x45)</span>
<span class="n">ipVer</span> <span class="kt">uint8</span> <span class="o">=</span> <span class="m">0x04</span> <span class="c">// 4; unused in this program, but represented for completion's sake.</span>
<span class="p">)</span>
<span class="k">var</span> <span class="p">(</span>
<span class="n">vihlLowerMask</span> <span class="kt">uint8</span> <span class="o">=</span> <span class="m">0x0f</span> <span class="c">// 15</span>
<span class="p">)</span>
<span class="k">func</span> <span class="n">ToVIHL</span><span class="p">(</span><span class="n">ver</span><span class="p">,</span> <span class="n">ihl</span> <span class="kt">uint8</span><span class="p">)</span> <span class="p">(</span><span class="n">vihl</span> <span class="kt">byte</span><span class="p">)</span> <span class="p">{</span>
<span class="c">// In Go, a byte is exactly equal to a uint8</span>
<span class="c">// so type casting/conversion is unnecessary here.</span>
<span class="n">vihl</span> <span class="o">=</span> <span class="p">(</span><span class="n">ver</span> <span class="o">&lt;&lt;</span> <span class="m">4</span><span class="p">)</span> <span class="o">|</span> <span class="p">(</span><span class="n">ihl</span> <span class="o">&amp;</span> <span class="n">vihlLowerMask</span><span class="p">)</span>
<span class="k">return</span>
<span class="p">}</span>
<span class="k">func</span> <span class="n">FromVIHL</span><span class="p">(</span><span class="n">vihl</span> <span class="kt">byte</span><span class="p">)</span> <span class="p">(</span><span class="n">ver</span><span class="p">,</span> <span class="n">ihl</span> <span class="kt">uint8</span><span class="p">)</span> <span class="p">{</span>
<span class="n">ver</span> <span class="o">=</span> <span class="n">vihl</span> <span class="o">&gt;&gt;</span> <span class="m">4</span>
<span class="n">ihl</span> <span class="o">=</span> <span class="n">vihl</span> <span class="o">&amp;</span> <span class="n">vihlLowerMask</span>
<span class="k">return</span>
<span class="p">}</span>
<span class="k">func</span> <span class="n">main</span><span class="p">()</span> <span class="p">{</span>
<span class="k">var</span> <span class="n">err</span> <span class="kt">error</span>
<span class="k">var</span> <span class="n">u64</span> <span class="kt">uint64</span>
<span class="k">var</span> <span class="n">vihl</span> <span class="kt">byte</span>
<span class="k">var</span> <span class="n">ver</span> <span class="kt">uint8</span>
<span class="k">var</span> <span class="n">ihl</span> <span class="kt">uint8</span>
<span class="c">// Given a V/IHL of vihlBits (see const at top)...</span>
<span class="k">if</span> <span class="n">u64</span><span class="p">,</span> <span class="n">err</span> <span class="o">=</span> <span class="n">strconv</span><span class="o">.</span><span class="n">ParseUint</span><span class="p">(</span><span class="n">vihlBits</span><span class="p">,</span> <span class="m">2</span><span class="p">,</span> <span class="m">8</span><span class="p">);</span> <span class="n">err</span> <span class="o">!=</span> <span class="no">nil</span> <span class="p">{</span>
<span class="n">log</span><span class="o">.</span><span class="n">Panicln</span><span class="p">(</span><span class="n">err</span><span class="p">)</span>
<span class="p">}</span>
<span class="n">vihl</span> <span class="o">=</span> <span class="kt">uint8</span><span class="p">(</span><span class="n">u64</span><span class="p">)</span>
<span class="c">// Prints:</span>
<span class="c">/*
V/IHL is: 69 (0x45)
*/</span>
<span class="n">fmt</span><span class="o">.</span><span class="n">Printf</span><span class="p">(</span><span class="s">"V/IHL is:</span><span class="se">\t\t</span><span class="s">%d (%#02x)</span><span class="se">\n</span><span class="s">"</span><span class="p">,</span> <span class="n">vihl</span><span class="p">,</span> <span class="n">vihl</span><span class="p">)</span>
<span class="n">ver</span><span class="p">,</span> <span class="n">ihl</span> <span class="o">=</span> <span class="n">FromVIHL</span><span class="p">(</span><span class="n">vihl</span><span class="p">)</span>
<span class="c">// Prints:</span>
<span class="c">/*
Version: 4 (0x04)
IHL: 5 (0x05)
*/</span>
<span class="n">fmt</span><span class="o">.</span><span class="n">Printf</span><span class="p">(</span>
<span class="s">"Version:</span><span class="se">\t\t</span><span class="s">%d (%#02x)</span><span class="se">\n</span><span class="s">"</span><span class="o">+</span>
<span class="s">"IHL:</span><span class="se">\t\t\t</span><span class="s">%d (%#02x)</span><span class="se">\n</span><span class="s">"</span><span class="p">,</span>
<span class="n">ver</span><span class="p">,</span> <span class="n">ver</span><span class="p">,</span>
<span class="n">ihl</span><span class="p">,</span> <span class="n">ihl</span><span class="p">,</span>
<span class="p">)</span>
<span class="n">vihl</span> <span class="o">=</span> <span class="n">ToVIHL</span><span class="p">(</span><span class="n">ver</span><span class="p">,</span> <span class="n">ihl</span><span class="p">)</span>
<span class="c">// Prints:</span>
<span class="c">/*
Confirmed V/IHL: 69 (0x45)
*/</span>
<span class="n">fmt</span><span class="o">.</span><span class="n">Printf</span><span class="p">(</span><span class="s">"Confirmed V/IHL:</span><span class="se">\t</span><span class="s">%d (%#02x)</span><span class="se">\n</span><span class="s">"</span><span class="p">,</span> <span class="n">vihl</span><span class="p">,</span> <span class="n">vihl</span><span class="p">)</span>
<span class="p">}</span></code></pre>
</div>
</div>
</div>
</details>
</div>
<div class="sect3">
<h4 id="xtra_bitpacked_de"><a class="link" href="#xtra_bitpacked_de">8.1.2. DSCP, ECN (IPv4)</a></h4>
<div class="paragraph">
<p>The DSCP and ECN fields are combined to make up a single byte with a 6-bit and 2-bit "nibble" each, respectively.</p>
</div>
<div class="admonitionblock note">
<table>
<tr>
<td class="icon">
<div class="title">Note</div>
</td>
<td class="content">
<div class="paragraph">
<p>The actual values for DSCP and ECN are sort of scattered about through several different RFCs.</p>
</div>
<div class="paragraph">
<p>Notable DSCP mentions are:</p>
</div>
<div class="ulist">
<ul>
<li>
<p><a href="https://datatracker.ietf.org/doc/html/rfc2474#section-4.2.2.1" target="_blank" rel="noopener">RFC 2474 § 4.2.2.1</a></p>
</li>
<li>
<p><a href="https://datatracker.ietf.org/doc/html/rfc2475" target="_blank" rel="noopener">RFC 2475</a></p>
</li>
<li>
<p><a href="https://datatracker.ietf.org/doc/html/rfc8837#section-5" target="_blank" rel="noopener">RFC 8837 § 5</a></p>
</li>
</ul>
</div>
<div class="paragraph">
<p>Notable ECN mentions are:</p>
</div>
<div class="ulist">
<ul>
<li>
<p><a href="https://datatracker.ietf.org/doc/html/rfc3168" target="_blank" rel="noopener">RFC 3168</a></p>
</li>
<li>
<p><a href="https://datatracker.ietf.org/doc/html/rfc6040" target="_blank" rel="noopener">RFC 6040</a></p>
</li>
<li>
<p><a href="https://datatracker.ietf.org/doc/html/rfc8311" target="_blank" rel="noopener">RFC 8311</a></p>
</li>
</ul>
</div>
</td>
</tr>
</table>
</div>
<details>
<summary class="title">Example in Go</summary>
<div class="content">
<div class="listingblock">
<div class="content">
<pre class="rouge highlight"><code data-lang="go"><span class="k">package</span> <span class="n">main</span>
<span class="k">import</span> <span class="p">(</span>
<span class="s">`fmt`</span>
<span class="s">`log`</span>
<span class="s">"strconv"</span>
<span class="p">)</span>
<span class="k">const</span> <span class="p">(</span>
<span class="c">/*
This is a nonsensical example.
The actual values are sort of scattered around a multitude of RFCs.
*/</span>
<span class="n">deBits</span> <span class="kt">string</span> <span class="o">=</span> <span class="s">"01010101"</span> <span class="c">// [0101 0101], or 85 (0x55)</span>
<span class="p">)</span>
<span class="k">var</span> <span class="p">(</span>
<span class="n">deLowerMask</span> <span class="kt">uint8</span> <span class="o">=</span> <span class="m">0x03</span> <span class="c">// 3</span>
<span class="p">)</span>
<span class="k">func</span> <span class="n">ToDE</span><span class="p">(</span><span class="n">dscp</span><span class="p">,</span> <span class="n">ecn</span> <span class="kt">uint8</span><span class="p">)</span> <span class="p">(</span><span class="n">de</span> <span class="kt">byte</span><span class="p">)</span> <span class="p">{</span>
<span class="n">de</span> <span class="o">=</span> <span class="p">(</span><span class="n">dscp</span> <span class="o">&lt;&lt;</span> <span class="m">2</span><span class="p">)</span> <span class="o">|</span> <span class="p">(</span><span class="n">ecn</span> <span class="o">&amp;</span> <span class="n">deLowerMask</span><span class="p">)</span>
<span class="k">return</span>
<span class="p">}</span>
<span class="k">func</span> <span class="n">FromDE</span><span class="p">(</span><span class="n">de</span> <span class="kt">byte</span><span class="p">)</span> <span class="p">(</span><span class="n">dscp</span><span class="p">,</span> <span class="n">ecn</span> <span class="kt">uint8</span><span class="p">)</span> <span class="p">{</span>
<span class="n">dscp</span> <span class="o">=</span> <span class="n">de</span> <span class="o">&gt;&gt;</span> <span class="m">2</span>
<span class="n">ecn</span> <span class="o">=</span> <span class="n">de</span> <span class="o">&amp;</span> <span class="n">deLowerMask</span>
<span class="k">return</span>
<span class="p">}</span>
<span class="k">func</span> <span class="n">main</span><span class="p">()</span> <span class="p">{</span>
<span class="k">var</span> <span class="n">err</span> <span class="kt">error</span>
<span class="k">var</span> <span class="n">u64</span> <span class="kt">uint64</span>
<span class="k">var</span> <span class="n">de</span> <span class="kt">byte</span>
<span class="k">var</span> <span class="n">dscp</span> <span class="kt">uint8</span>
<span class="k">var</span> <span class="n">ecn</span> <span class="kt">uint8</span>
<span class="c">// Given a D/E of deBits (see const at top)...</span>
<span class="k">if</span> <span class="n">u64</span><span class="p">,</span> <span class="n">err</span> <span class="o">=</span> <span class="n">strconv</span><span class="o">.</span><span class="n">ParseUint</span><span class="p">(</span><span class="n">deBits</span><span class="p">,</span> <span class="m">2</span><span class="p">,</span> <span class="m">8</span><span class="p">);</span> <span class="n">err</span> <span class="o">!=</span> <span class="no">nil</span> <span class="p">{</span>
<span class="n">log</span><span class="o">.</span><span class="n">Panicln</span><span class="p">(</span><span class="n">err</span><span class="p">)</span>
<span class="p">}</span>
<span class="n">de</span> <span class="o">=</span> <span class="kt">uint8</span><span class="p">(</span><span class="n">u64</span><span class="p">)</span>
<span class="c">// Prints:</span>
<span class="c">/*
D/E is: 85 (0x55)
*/</span>
<span class="n">fmt</span><span class="o">.</span><span class="n">Printf</span><span class="p">(</span><span class="s">"D/E is:</span><span class="se">\t\t</span><span class="s">%d (%#02x)</span><span class="se">\n</span><span class="s">"</span><span class="p">,</span> <span class="n">de</span><span class="p">,</span> <span class="n">de</span><span class="p">)</span>
<span class="n">dscp</span><span class="p">,</span> <span class="n">ecn</span> <span class="o">=</span> <span class="n">FromDE</span><span class="p">(</span><span class="n">de</span><span class="p">)</span>
<span class="c">// Prints:</span>
<span class="c">/*
DSCP: 21 (0x15)
ECN: 1 (0x01)
*/</span>
<span class="n">fmt</span><span class="o">.</span><span class="n">Printf</span><span class="p">(</span>
<span class="s">"DSCP:</span><span class="se">\t\t</span><span class="s">%d (%#02x)</span><span class="se">\n</span><span class="s">"</span><span class="o">+</span>
<span class="s">"ECN:</span><span class="se">\t\t</span><span class="s">%d (%#02x)</span><span class="se">\n</span><span class="s">"</span><span class="p">,</span>
<span class="n">dscp</span><span class="p">,</span> <span class="n">dscp</span><span class="p">,</span>
<span class="n">ecn</span><span class="p">,</span> <span class="n">ecn</span><span class="p">,</span>
<span class="p">)</span>
<span class="n">de</span> <span class="o">=</span> <span class="n">ToDE</span><span class="p">(</span><span class="n">dscp</span><span class="p">,</span> <span class="n">ecn</span><span class="p">)</span>
<span class="c">// Prints:</span>
<span class="c">/*
Confirmed D/E: 85 (0x55)
*/</span>
<span class="n">fmt</span><span class="o">.</span><span class="n">Printf</span><span class="p">(</span><span class="s">"Confirmed D/E:</span><span class="se">\t</span><span class="s">%d (%#02x)</span><span class="se">\n</span><span class="s">"</span><span class="p">,</span> <span class="n">de</span><span class="p">,</span> <span class="n">de</span><span class="p">)</span>
<span class="p">}</span></code></pre>
</div>
</div>
</div>
</details>
</div>
<div class="sect3">
<h4 id="xtra_bitpacked_frag"><a class="link" href="#xtra_bitpacked_frag">8.1.3. Flags, Fragmentation Offset (IPv4)</a></h4>
<div class="paragraph">
<p>The (Fragmentation) Flags and Fragmentation Offset fields are combined to make up 2 bytes with a 3-bit and 13-bit "nibble"/"word" each, respectively.</p>
</div>
<div class="paragraph">
<p>The Fragmentation Flags and Offset are defined in <a href="https://datatracker.ietf.org/doc/html/rfc791#section-3.1" target="_blank" rel="noopener">RFC 791 § 3.1</a> and part of <a href="https://datatracker.ietf.org/doc/html/rfc815" target="_blank" rel="noopener">RFC 815</a>.</p>
</div>
<details>
<summary class="title">Example in Go</summary>
<div class="content">
<div class="listingblock">
<div class="content">
<pre class="rouge highlight"><code data-lang="go"><span class="k">package</span> <span class="n">main</span>
<span class="k">import</span> <span class="p">(</span>
<span class="s">`fmt`</span>
<span class="s">`log`</span>
<span class="s">"strconv"</span>
<span class="p">)</span>
<span class="k">const</span> <span class="p">(</span>
<span class="c">/*
This is a nonsensical example.
*/</span>
<span class="n">fragBits</span> <span class="kt">string</span> <span class="o">=</span> <span class="s">"0101010101000100"</span> <span class="c">// [0101 0101 0100 0100], or 21828 (0x5544)</span>
<span class="p">)</span>
<span class="k">var</span> <span class="p">(</span>
<span class="n">fragOffset</span> <span class="kt">uint16</span> <span class="o">=</span> <span class="m">0x000d</span> <span class="c">// 13</span>
<span class="n">fragFlagMask</span> <span class="kt">uint16</span> <span class="o">=</span> <span class="m">0x07</span> <span class="c">// 0b0000111 to mask 3 bits</span>
<span class="n">fragOffsetMask</span> <span class="kt">uint16</span> <span class="o">=</span> <span class="m">0x1fff</span> <span class="c">// 8191, a 13-bit mask</span>
<span class="p">)</span>
<span class="k">func</span> <span class="n">ToFrag</span><span class="p">(</span><span class="n">flags</span><span class="p">,</span> <span class="n">fo</span> <span class="kt">uint16</span><span class="p">)</span> <span class="p">(</span><span class="n">frag</span> <span class="kt">uint16</span><span class="p">)</span> <span class="p">{</span>
<span class="n">frag</span> <span class="o">=</span> <span class="p">(</span><span class="n">flags</span> <span class="o">&lt;&lt;</span> <span class="n">fragOffset</span><span class="p">)</span> <span class="o">|</span> <span class="p">(</span><span class="n">fo</span> <span class="o">&amp;</span> <span class="n">fragOffsetMask</span><span class="p">)</span>
<span class="k">return</span>
<span class="p">}</span>
<span class="k">func</span> <span class="n">FromFrag</span><span class="p">(</span><span class="n">frag</span> <span class="kt">uint16</span><span class="p">)</span> <span class="p">(</span><span class="n">flags</span><span class="p">,</span> <span class="n">fo</span> <span class="kt">uint16</span><span class="p">)</span> <span class="p">{</span>
<span class="n">flags</span> <span class="o">=</span> <span class="p">(</span><span class="n">frag</span> <span class="o">&gt;&gt;</span> <span class="n">fragOffset</span><span class="p">)</span> <span class="o">&amp;</span> <span class="n">fragFlagMask</span>
<span class="n">fo</span> <span class="o">=</span> <span class="n">frag</span> <span class="o">&amp;</span> <span class="n">fragOffsetMask</span>
<span class="k">return</span>
<span class="p">}</span>
<span class="k">func</span> <span class="n">main</span><span class="p">()</span> <span class="p">{</span>
<span class="k">var</span> <span class="n">err</span> <span class="kt">error</span>
<span class="k">var</span> <span class="n">u64</span> <span class="kt">uint64</span>
<span class="k">var</span> <span class="n">frag</span> <span class="kt">uint16</span>
<span class="k">var</span> <span class="n">flags</span> <span class="kt">uint16</span>
<span class="k">var</span> <span class="n">fo</span> <span class="kt">uint16</span>
<span class="c">// Given a fragmentation configuration of fragBits (see const at top)...</span>
<span class="k">if</span> <span class="n">u64</span><span class="p">,</span> <span class="n">err</span> <span class="o">=</span> <span class="n">strconv</span><span class="o">.</span><span class="n">ParseUint</span><span class="p">(</span><span class="n">fragBits</span><span class="p">,</span> <span class="m">2</span><span class="p">,</span> <span class="m">16</span><span class="p">);</span> <span class="n">err</span> <span class="o">!=</span> <span class="no">nil</span> <span class="p">{</span>
<span class="n">log</span><span class="o">.</span><span class="n">Panicln</span><span class="p">(</span><span class="n">err</span><span class="p">)</span>
<span class="p">}</span>
<span class="n">frag</span> <span class="o">=</span> <span class="kt">uint16</span><span class="p">(</span><span class="n">u64</span><span class="p">)</span>
<span class="c">// Prints:</span>
<span class="c">/*
Frag is: 21828 (0x5544)
*/</span>
<span class="n">fmt</span><span class="o">.</span><span class="n">Printf</span><span class="p">(</span><span class="s">"Frag is:</span><span class="se">\t\t</span><span class="s">%d (%#04x)</span><span class="se">\n</span><span class="s">"</span><span class="p">,</span> <span class="n">frag</span><span class="p">,</span> <span class="n">frag</span><span class="p">)</span>
<span class="n">flags</span><span class="p">,</span> <span class="n">fo</span> <span class="o">=</span> <span class="n">FromFrag</span><span class="p">(</span><span class="n">frag</span><span class="p">)</span>
<span class="c">// Prints:</span>
<span class="c">/*
Flags: 2 (0x0002)
Fragmentation Offset: 5444 (0x1544)
*/</span>
<span class="n">fmt</span><span class="o">.</span><span class="n">Printf</span><span class="p">(</span>
<span class="s">"Flags:</span><span class="se">\t\t\t</span><span class="s">%d (%#04x)</span><span class="se">\n</span><span class="s">"</span><span class="o">+</span>
<span class="s">"Fragmentation Offset:</span><span class="se">\t</span><span class="s">%d (%#04x)</span><span class="se">\n</span><span class="s">"</span><span class="p">,</span>
<span class="n">flags</span><span class="p">,</span> <span class="n">flags</span><span class="p">,</span>
<span class="n">fo</span><span class="p">,</span> <span class="n">fo</span><span class="p">,</span>
<span class="p">)</span>
<span class="n">frag</span> <span class="o">=</span> <span class="n">ToFrag</span><span class="p">(</span><span class="n">flags</span><span class="p">,</span> <span class="n">fo</span><span class="p">)</span>
<span class="c">// Prints:</span>
<span class="c">/*
Confirmed Frag: 21828 (0x5544)
*/</span>
<span class="n">fmt</span><span class="o">.</span><span class="n">Printf</span><span class="p">(</span><span class="s">"Confirmed Frag:</span><span class="se">\t\t</span><span class="s">%d (%#02x)</span><span class="se">\n</span><span class="s">"</span><span class="p">,</span> <span class="n">frag</span><span class="p">,</span> <span class="n">frag</span><span class="p">)</span>
<span class="p">}</span></code></pre>
</div>
</div>
</div>
</details>
</div>
<div class="sect3">
<h4 id="xtra_bitpacked_vtf"><a class="link" href="#xtra_bitpacked_vtf">8.1.4. IP Version, Traffic Class, Flow Label (IPv6)</a></h4>
<div class="paragraph">
<p>IPv6 thankfully only has one bitpacking in the header. Unfortunately, it&#8217;s a triple-whammy.</p>
</div>
<div class="paragraph">
<p>These are mostly defined in:</p>
</div>
<div class="ulist">
<ul>
<li>
<p><a href="https://datatracker.ietf.org/doc/html/rfc8200#section-3" target="_blank" rel="noopener">RFC 8200 § 3</a> for the header format</p>
</li>
<li>
<p><a href="https://datatracker.ietf.org/doc/html/rfc8200#section-7" target="_blank" rel="noopener">RFC 8200 § 7</a> for the Traffic Class field</p>
</li>
<li>
<p><a href="https://datatracker.ietf.org/doc/html/rfc8200#section-6" target="_blank" rel="noopener">RFC 8200 § 6</a> for the Flow Label field</p>
</li>
</ul>
</div>
<div class="paragraph">
<p>The IP Version takes up 4 bits (just as in IPv4, except it will always be <code>6</code> this time), the Traffic Class field takes up 8 bits, and Flow Labels takes up 20 bits for a total of 32 bits (4 bytes).</p>
</div>
<details>
<summary class="title">Example in Go</summary>
<div class="content">
<div class="listingblock">
<div class="content">
<pre class="rouge highlight"><code data-lang="go"><span class="k">package</span> <span class="n">main</span>
<span class="k">import</span> <span class="p">(</span>
<span class="s">`fmt`</span>
<span class="s">`log`</span>
<span class="s">"strconv"</span>
<span class="p">)</span>
<span class="k">const</span> <span class="p">(</span>
<span class="c">/*
This is a nonsensical example.
*/</span>
<span class="n">vtfBits</span> <span class="kt">string</span> <span class="o">=</span> <span class="s">"01100000000000000000000000000000"</span> <span class="c">// [0110 0000 0000 0000 0000 0000 0000 0000], or 1610612736 (0x60000000)</span>
<span class="p">)</span>
<span class="k">var</span> <span class="p">(</span>
<span class="n">vtfVOffset</span> <span class="kt">uint32</span> <span class="o">=</span> <span class="m">0x0000001c</span> <span class="c">// 28</span>
<span class="n">vtfVFlagMask</span> <span class="kt">uint32</span> <span class="o">=</span> <span class="m">0x0000000f</span> <span class="c">// Mask to 4 bits</span>
<span class="n">vtfTOffset</span> <span class="kt">uint32</span> <span class="o">=</span> <span class="m">0x00000014</span> <span class="c">// 20</span>
<span class="n">vtfTFlagMask</span> <span class="kt">uint32</span> <span class="o">=</span> <span class="m">0x000000ff</span> <span class="c">// mask to 8 bits</span>
<span class="n">vtfFlowMask</span> <span class="kt">uint32</span> <span class="o">=</span> <span class="m">0x0000ffff</span>
<span class="p">)</span>
<span class="k">func</span> <span class="n">ToVTF</span><span class="p">(</span><span class="n">ver</span><span class="p">,</span> <span class="n">tc</span><span class="p">,</span> <span class="n">flow</span> <span class="kt">uint32</span><span class="p">)</span> <span class="p">(</span><span class="n">vtf</span> <span class="kt">uint32</span><span class="p">)</span> <span class="p">{</span>
<span class="n">vtf</span> <span class="o">=</span> <span class="p">(</span><span class="n">ver</span> <span class="o">&lt;&lt;</span> <span class="n">vtfVOffset</span><span class="p">)</span> <span class="o">|</span> <span class="p">(</span><span class="n">tc</span> <span class="o">&lt;&lt;</span> <span class="n">vtfTOffset</span><span class="p">)</span> <span class="o">|</span> <span class="p">(</span><span class="n">flow</span> <span class="o">&amp;</span> <span class="n">vtfFlowMask</span><span class="p">)</span>
<span class="k">return</span>
<span class="p">}</span>
<span class="k">func</span> <span class="n">FromVTF</span><span class="p">(</span><span class="n">vtf</span> <span class="kt">uint32</span><span class="p">)</span> <span class="p">(</span><span class="n">ver</span><span class="p">,</span> <span class="n">tc</span><span class="p">,</span> <span class="n">flow</span> <span class="kt">uint32</span><span class="p">)</span> <span class="p">{</span>
<span class="n">ver</span> <span class="o">=</span> <span class="p">(</span><span class="n">vtf</span> <span class="o">&gt;&gt;</span> <span class="n">vtfVOffset</span><span class="p">)</span> <span class="o">&amp;</span> <span class="n">vtfVFlagMask</span>
<span class="n">tc</span> <span class="o">=</span> <span class="p">(</span><span class="n">vtf</span> <span class="o">&gt;&gt;</span> <span class="n">vtfTOffset</span><span class="p">)</span> <span class="o">&amp;</span> <span class="n">vtfTFlagMask</span>
<span class="n">flow</span> <span class="o">=</span> <span class="n">vtf</span> <span class="o">&amp;</span> <span class="n">vtfFlowMask</span>
<span class="k">return</span>
<span class="p">}</span>
<span class="k">func</span> <span class="n">main</span><span class="p">()</span> <span class="p">{</span>
<span class="k">var</span> <span class="n">err</span> <span class="kt">error</span>
<span class="k">var</span> <span class="n">u64</span> <span class="kt">uint64</span>
<span class="k">var</span> <span class="n">vtf</span> <span class="kt">uint32</span>
<span class="k">var</span> <span class="n">ver</span> <span class="kt">uint32</span>
<span class="k">var</span> <span class="n">tc</span> <span class="kt">uint32</span>
<span class="k">var</span> <span class="n">flow</span> <span class="kt">uint32</span>
<span class="c">// Given a fragmentation configuration of vtfBits (see const at top)...</span>
<span class="k">if</span> <span class="n">u64</span><span class="p">,</span> <span class="n">err</span> <span class="o">=</span> <span class="n">strconv</span><span class="o">.</span><span class="n">ParseUint</span><span class="p">(</span><span class="n">vtfBits</span><span class="p">,</span> <span class="m">2</span><span class="p">,</span> <span class="m">32</span><span class="p">);</span> <span class="n">err</span> <span class="o">!=</span> <span class="no">nil</span> <span class="p">{</span>
<span class="n">log</span><span class="o">.</span><span class="n">Panicln</span><span class="p">(</span><span class="n">err</span><span class="p">)</span>
<span class="p">}</span>
<span class="n">vtf</span> <span class="o">=</span> <span class="kt">uint32</span><span class="p">(</span><span class="n">u64</span><span class="p">)</span>
<span class="c">// Prints:</span>
<span class="c">/*
VTF is: 1610612736 (0x60000000)
*/</span>
<span class="n">fmt</span><span class="o">.</span><span class="n">Printf</span><span class="p">(</span><span class="s">"VTF is:</span><span class="se">\t\t\t</span><span class="s">%d (%#04x)</span><span class="se">\n</span><span class="s">"</span><span class="p">,</span> <span class="n">vtf</span><span class="p">,</span> <span class="n">vtf</span><span class="p">)</span>
<span class="n">ver</span><span class="p">,</span> <span class="n">tc</span><span class="p">,</span> <span class="n">flow</span> <span class="o">=</span> <span class="n">FromVTF</span><span class="p">(</span><span class="n">vtf</span><span class="p">)</span>
<span class="c">// Prints:</span>
<span class="c">/*
VTF is: 1610612736 (0x60000000)
Version: 6 (0x0006)
Traffic Class: 0 (0x0000)
Flow Label: 0 (0x0000)
*/</span>
<span class="n">fmt</span><span class="o">.</span><span class="n">Printf</span><span class="p">(</span>
<span class="s">"Version:</span><span class="se">\t\t</span><span class="s">%d (%#04x)</span><span class="se">\n</span><span class="s">"</span><span class="o">+</span>
<span class="s">"Traffic Class:</span><span class="se">\t\t</span><span class="s">%d (%#04x)</span><span class="se">\n</span><span class="s">"</span><span class="o">+</span>
<span class="s">"Flow Label:</span><span class="se">\t\t</span><span class="s">%d (%#04x)</span><span class="se">\n</span><span class="s">"</span><span class="p">,</span>
<span class="n">ver</span><span class="p">,</span> <span class="n">ver</span><span class="p">,</span>
<span class="n">tc</span><span class="p">,</span> <span class="n">tc</span><span class="p">,</span>
<span class="n">flow</span><span class="p">,</span> <span class="n">flow</span><span class="p">,</span>
<span class="p">)</span>
<span class="n">vtf</span> <span class="o">=</span> <span class="n">ToVTF</span><span class="p">(</span><span class="n">ver</span><span class="p">,</span> <span class="n">tc</span><span class="p">,</span> <span class="n">flow</span><span class="p">)</span>
<span class="c">// Prints:</span>
<span class="c">/*
Confirmed V/T/F: 1610612736 (0x60000000)
*/</span>
<span class="n">fmt</span><span class="o">.</span><span class="n">Printf</span><span class="p">(</span><span class="s">"Confirmed V/T/F:</span><span class="se">\t</span><span class="s">%d (%#02x)</span><span class="se">\n</span><span class="s">"</span><span class="p">,</span> <span class="n">vtf</span><span class="p">,</span> <span class="n">vtf</span><span class="p">)</span>
<span class="p">}</span></code></pre>
</div>
</div>
</div>
</details>
</div>
</div>
</div>
</div>
</div>
<div id="footer">
<div id="footer-text">
Last updated 2025-08-28 07:15:54 -0400
</div>
</div>
</body>
</html>