From 020029ea5bac1aa1266db45c56d28c2b163788a0 Mon Sep 17 00:00:00 2001
From: Brad Davis <brd@FreeBSD.org>
Date: Sun, 14 Aug 2016 16:06:03 +0000
Subject: [PATCH] Add a section on how to configure VLANs.

---
 .../handbook/advanced-networking/chapter.xml  | 57 +++++++++++++++++++
 1 file changed, 57 insertions(+)

diff --git a/en_US.ISO8859-1/books/handbook/advanced-networking/chapter.xml b/en_US.ISO8859-1/books/handbook/advanced-networking/chapter.xml
index f9b312009b..b455c61708 100644
--- a/en_US.ISO8859-1/books/handbook/advanced-networking/chapter.xml
+++ b/en_US.ISO8859-1/books/handbook/advanced-networking/chapter.xml
@@ -50,6 +50,11 @@
 	  Address Redundancy Protocol (<acronym>CARP</acronym>) in
 	  &os;.</para>
       </listitem>
+
+      <listitem>
+	<para>How to configure multiple <acronym>VLANs</acronym> on
+	  &os;.</para>
+      </listitem>
     </itemizedlist>
 
     <para>Before reading this chapter, you should:</para>
@@ -5201,4 +5206,56 @@ ifconfig_carp1="vhid <replaceable>2</replaceable> advskew <replaceable>100</repl
 	enabled.</para>
     </sect2>
   </sect1>
+  <sect1 xml:id="network-vlan">
+    <info>
+      <title>VLANs</title>
+    </info>
+
+    <indexterm>
+      <primary><acronym>VLANs</acronym></primary>
+    </indexterm>
+    <indexterm>
+      <primary>Virtual LANs</primary>
+    </indexterm>
+
+    <para><acronym>VLANs</acronym> are a way of virtually dividing up a
+      network into many different subnetworks.  Each will have its own
+      broadcast domain and be isolated from the rest of the
+      <acronym>VLANs</acronym>.</para>
+
+    <para>On &os;, <acronym>VLANs</acronym> must be supported by the network
+      card driver.  To see which drivers support vlans, refer to the
+      &man.vlan.4; manual page.</para>
+
+    <para>When configuring a <acronym>VLAN</acronym>, a couple pieces of
+      information must be known.  First, which network interface?  Second,
+      what is the <acronym>VLAN</acronym> tag?</para>
+
+    <para>To configure <acronym>VLANs</acronym> at run time, with a
+      <acronym>NIC</acronym> of <literal>em0</literal> and a
+      <acronym>VLAN</acronym> tag of <systemitem>5</systemitem>.  The command
+      would look like this:</para>
+
+    <screen>&prompt.root; <userinput>ifconfig <replaceable>em0.5</replaceable> create vlan <replaceable>5</replaceable> vlandev <replaceable>em0</replaceable> inet 192.168.20.20/24</userinput></screen>
+
+    <note>
+      <para>See how the interface name includes the <acronym>NIC</acronym>
+	driver name and the <acronym>VLAN</acronym> tag, separated by a
+	period?  This is a best practice to make maintaining the
+	<acronym>VLAN</acronym> configuration easy when many
+	<acronym>VLANs</acronym> are present on a machine.</para>
+    </note>
+
+    <para>To configure <acronym>VLANs</acronym> at boot time,
+      <filename>/etc/rc.conf</filename> must be updated.  To duplicate the
+      configuration above, the following will need to be added:</para>
+
+    <programlisting>vlans_<replaceable>em0</replaceable>="<replaceable>5</replaceable>"
+vlans_<replaceable>em0</replaceable>_<replaceable>5</replaceable>="inet 192.168.20.20/24"</programlisting>
+
+    <para>Additional <acronym>VLANs</acronym> may be added, by simply adding
+      the tag to the <literal>vlans_<replaceable>em0</replaceable></literal>
+      field and adding an additional line configuring the network on that
+      <acronym>VLAN</acronym> tag's interface.</para>
+  </sect1>
 </chapter>