From 1282c75d0686b2b3d1403fb0869ce1ea3e6a4c39 Mon Sep 17 00:00:00 2001
From: Sevan Janiyan <sevan@FreeBSD.org>
Date: Sun, 10 Jun 2018 18:31:35 +0000
Subject: [PATCH] Cover using symbolic names for interfaces in VLAN article.

PR:		228231
Submitted by:	Brian Haug <haug.bsd6114 AT yahoo dot com>
Approved by:	bcr (mentor)
Differential Revision:	https://reviews.freebsd.org/D15586
---
 .../handbook/advanced-networking/chapter.xml  | 40 +++++++++++++++++--
 1 file changed, 37 insertions(+), 3 deletions(-)

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 2fd7d14c6b..4324388b05 100644
--- a/en_US.ISO8859-1/books/handbook/advanced-networking/chapter.xml
+++ b/en_US.ISO8859-1/books/handbook/advanced-networking/chapter.xml
@@ -5225,8 +5225,9 @@ ifconfig_carp1="vhid <replaceable>2</replaceable> advskew <replaceable>100</repl
     </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
+      a network into many different subnetworks, also referred
+      to as segmenting.  Each segment will have its
+      own broadcast domain and be isolated from other
       <acronym>VLANs</acronym>.</para>
 
     <para>On &os;, <acronym>VLANs</acronym> must be supported by the
@@ -5239,7 +5240,7 @@ ifconfig_carp1="vhid <replaceable>2</replaceable> advskew <replaceable>100</repl
 
     <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
+      <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>
@@ -5266,5 +5267,38 @@ ifconfig_<replaceable>em0</replaceable>_<replaceable>5</replaceable>="inet 192.1
       <literal>vlans_<replaceable>em0</replaceable></literal>
       field and adding an additional line configuring the network on
       that <acronym>VLAN</acronym> tag's interface.</para>
+
+    <para>It is useful to assign a symbolic name to an interface so
+      that when the associated hardware is changed, only a few
+      configuration variables need to be updated.  For example,
+      security cameras need to be run over VLAN 1 on
+      <literal>em0</literal>.  Later, if the <literal>em0</literal>
+      card is replaced with a card that uses the &man.ixgb.4; driver,
+      all references to <literal>em0.1</literal> will not have to
+      change to <literal>ixgb0.1</literal>.</para>
+
+    <para>To configure <acronym>VLAN</acronym>
+      <systemitem>5</systemitem>, on the
+      <acronym>NIC</acronym> <literal>em0</literal>, assign the
+      interface name <literal>cameras</literal>, and assign the
+      interface an IP address of <systemitem
+      class="ipaddress"><replaceable>192.168.20.20</replaceable></systemitem>
+      with a <systemitem class="netmask">24</systemitem>-bit prefix,
+      use this command:</para>
+
+    <screen>&prompt.root; <userinput>ifconfig <replaceable>em0.5</replaceable> create vlan <replaceable>5</replaceable> vlandev <replaceable>em0</replaceable> name <replaceable>cameras</replaceable> inet <replaceable>192.168.20.20/24</replaceable></userinput></screen>
+
+    <para>For an interface named <literal>video</literal>, use the
+    following:</para>
+
+    <screen>&prompt.root; <userinput>ifconfig <replaceable>video.5</replaceable> create vlan <replaceable>5</replaceable> vlandev <replaceable>video</replaceable> name <replaceable>cameras inet 192.168.20.20/24</replaceable></userinput></screen>
+
+  <para>To apply the changes at boot time, add the following lines to
+  <filename>/etc/rc.conf</filename>:</para>
+
+  <programlisting>vlans_<replaceable>video</replaceable>="<replaceable>camera</replaceable>"
+create_args_<replaceable>camera</replaceable>="vlan <replaceable>5</replaceable>"
+ifconfig_<replaceable>camera</replaceable>="inet <replaceable>192.168.20.20/24</replaceable>"</programlisting>
+
   </sect1>
 </chapter>