svn commit: r44141 - head/en_US.ISO8859-1/books/handbook/advanced-networking

Dru Lavigne dru at FreeBSD.org
Wed Mar 5 21:39:21 UTC 2014


Author: dru
Date: Wed Mar  5 21:39:21 2014
New Revision: 44141
URL: http://svnweb.freebsd.org/changeset/doc/44141

Log:
  Initial shuffle in prep for technical review of this chapter.
  More commits to come.
  
  Sponsored by: iXsystems

Modified:
  head/en_US.ISO8859-1/books/handbook/advanced-networking/chapter.xml

Modified: head/en_US.ISO8859-1/books/handbook/advanced-networking/chapter.xml
==============================================================================
--- head/en_US.ISO8859-1/books/handbook/advanced-networking/chapter.xml	Wed Mar  5 20:29:33 2014	(r44140)
+++ head/en_US.ISO8859-1/books/handbook/advanced-networking/chapter.xml	Wed Mar  5 21:39:21 2014	(r44141)
@@ -103,73 +103,91 @@
       <primary>subnet</primary>
     </indexterm>
 
-    <para>For one machine to be able to find another over a network,
-      there must be a mechanism in place to describe how to get from
-      one to the other.  This is called
-      <firstterm>routing</firstterm>.  A <quote>route</quote> is a
-      defined pair of addresses: a <quote>destination</quote> and a
-      <quote>gateway</quote>.  The pair indicates that when trying
-      to get to this <emphasis>destination</emphasis>, communicate
-      through this <emphasis>gateway</emphasis>.  There are three
+    <para><firstterm>Routing</firstterm> is the mechanism that allows
+      a system to find the network path to another system.
+      A <firstterm>route</firstterm> is a
+      defined pair of addresses which represent the <quote>destination</quote> and a
+      <quote>gateway</quote>.  The route indicates that when trying
+      to get to the specified destination, send the packets
+      through the specified gateway.  There are three
       types of destinations: individual hosts, subnets, and
       <quote>default</quote>.  The <quote>default route</quote> is
-      used if none of the other routes apply.  There are also three
-      types of gateways: individual hosts, interfaces (also called
-      <quote>links</quote>), and Ethernet hardware
-      (<acronym>MAC</acronym>) addresses.</para>
+      used if no other routes apply.  There are also three
+      types of gateways: individual hosts, interfaces, also called
+      links, and Ethernet hardware
+      (<acronym>MAC</acronym>) addresses.  Known routes are stored in
+      a routing table.</para>
+      
+    <para>This section provides an overview of routing basics.  It
+      then demonstrates how to configure a &os; system as a router and
+      offers some troubleshooting tips.</para>
 
-    <sect2>
-      <title>An Example</title>
+    <sect2 xml:id="network-routing-default">
+      <title>Routing Basics</title>
 
-      <para>This example &man.netstat.1; output illustrates several
-	aspects of routing:</para>
+      <para>To view the routing table of a &os; system, use &man.netstat.1;:</para>
 
       <screen>&prompt.user; <userinput>netstat -r</userinput>
 Routing tables
 
+Internet:
 Destination      Gateway            Flags     Refs     Use     Netif Expire
-
-default          outside-gw         UGSc       37      418      ppp0
+default          outside-gw         UGSc       37      418       em0
 localhost        localhost          UH          0      181       lo0
-test0            0:e0:b5:36:cf:4f   UHLW        5    63288       ed0     77
+test0            0:e0:b5:36:cf:4f   UHLW        5    63288       re0     77
 10.20.30.255     link#1             UHLW        1     2421
 example.com      link#1             UC          0        0
 host1            0:e0:a8:37:8:1e    UHLW        3     4601       lo0
 host2            0:e0:a8:37:8:1e    UHLW        0        5       lo0 =>
-host2.example.com link#1             UC          0        0
+host2.example.com link#1            UC          0        0
 224              link#1             UC          0        0</screen>
 
-      <indexterm>
-	<primary>default route</primary>
-      </indexterm>
+      <para>The entries in this example are as follows:</para>
 
-      <para>The first two lines specify the default route, described
-	in more detail in <xref linkend="network-routing-default"/>,
-	and the <systemitem>localhost</systemitem> route.</para>
+      <variablelist>
+	<varlistentry>
+	  <term>default</term>
+	  <listitem>
+      <para>The first line specifies the <literal></literal>
+	route.  When the local system needs to make a connection to a
+	remote host, it checks the routing table to determine if a
+	known path exists.  If the remote host falls into a subnet
+	that it knows how to reach, the system checks to see if it
+	can connect using that interface.</para>
 
-      <indexterm>
-	<primary>loopback device</primary>
-      </indexterm>
+      <para>If all known paths fail, the system has one last option:
+	the <quote>default</quote> route.  This route is a special
+	type of gateway route (usually the only one present in the
+	system), and is always marked with a <literal>c</literal> in
+	the flags field.  For hosts on a local area network, this
+	gateway is set to the system which has a direct connection to
+	the Internet.</para>
+
+      </listitem>
+    </varlistentry>
 
-      <para>The interface (<literal>Netif</literal> column) that this
+      <varlistentry>
+	<term>localhost</term>
+	<listitem>
+      <para>The second line is the <literal>localhost</literal> route.
+	The interface (<literal>Netif</literal> column) that this
 	routing table specifies to use for
 	<literal>localhost</literal> is <filename>lo0</filename>,
 	also known as the loopback device.  This says to keep all
 	traffic for this destination internal, rather than sending it
 	out over the network.</para>
+      </listitem>
+    </varlistentry>
 
-      <indexterm>
-	<primary>Ethernet</primary>
-	<secondary>MAC address</secondary>
-      </indexterm>
-
+      <varlistentry>
+	<term>MAC address</term>
+	<listitem>
       <para>The addresses beginning with <systemitem
-	  class="etheraddress">0:e0:</systemitem> are Ethernet
-	hardware addresses, also known as <acronym>MAC</acronym>
+	  class="etheraddress">0:e0:</systemitem> are <acronym>MAC</acronym>
 	addresses.  &os; will automatically identify any hosts,
 	<systemitem>test0</systemitem> in the example, on the local
 	Ethernet and add a route for that host over the Ethernet
-	interface, <filename>ed0</filename>.  This type of route has a
+	interface, <filename>re0</filename>.  This type of route has a
 	timeout, seen in the <literal>Expire</literal> column, which
 	is used if the host does not respond in a specific amount of
 	time.  When this happens, the route to this host will be
@@ -177,11 +195,12 @@ host2.example.com link#1             UC 
 	Routing Information Protocol (<acronym>RIP</acronym>), which
 	calculates routes to local hosts based upon a shortest path
 	determination.</para>
+      </listitem>
+    </varlistentry>
 
-      <indexterm>
-	<primary>subnet</primary>
-      </indexterm>
-
+      <varlistentry>
+	<term>subnet</term>
+	<listitem>
       <para>&os; will add subnet routes for the local subnet.
 	<systemitem class="ipaddress">10.20.30.255</systemitem> is the
 	broadcast address for the subnet <systemitem
@@ -195,7 +214,12 @@ host2.example.com link#1             UC 
 	automatically configured by a daemon called &man.routed.8;.
 	If it is not running, only routes which are statically defined
 	by the administrator will exist.</para>
+      </listitem>
+    </varlistentry>
 
+      <varlistentry>
+	<term>host</term>
+	<listitem>
       <para>The <literal>host1</literal> line refers to the host
 	by its Ethernet address.  Since it is the sending host, &os;
 	knows to use the loopback interface
@@ -210,12 +234,20 @@ host2.example.com link#1             UC 
 	show up on the host that supports the alias; all other hosts
 	on the local network will have a
 	<literal>link#1</literal> line for such routes.</para>
+      </listitem>
+    </varlistentry>
 
+      <varlistentry>
+	<term>224</term>
+	<listitem>
       <para>The final line (destination subnet <systemitem
 	  class="ipaddress">224</systemitem>) deals with
 	multicasting.</para>
+      </listitem>
+    </varlistentry>
+  </variablelist>
 
-      <para>Finally, various attributes of each route can be seen in
+      <para>Various attributes of each route can be seen in
 	the <literal>Flags</literal> column.  Below is a short table
 	of some of these flags and their meanings:</para>
 
@@ -271,30 +303,8 @@ host2.example.com link#1             UC 
 	  </tbody>
 	</tgroup>
       </informaltable>
-    </sect2>
-
-    <sect2 xml:id="network-routing-default">
-      <title>Default Routes</title>
-
-      <indexterm>
-	<primary>default route</primary>
-      </indexterm>
-
-      <para>When the local system needs to make a connection to a
-	remote host, it checks the routing table to determine if a
-	known path exists.  If the remote host falls into a subnet
-	that it knows how to reach, the system checks to see if it
-	can connect using that interface.</para>
-
-      <para>If all known paths fail, the system has one last option:
-	the <quote>default</quote> route.  This route is a special
-	type of gateway route (usually the only one present in the
-	system), and is always marked with a <literal>c</literal> in
-	the flags field.  For hosts on a local area network, this
-	gateway is set to the system which has a direct connection to
-	the Internet.</para>
-
-      <para>The default route for a machine which itself is
+      
+       <para>The default route for a machine which itself is
 	functioning as the gateway to the outside world, will be the
 	gateway machine at the Internet Service Provider
 	(<acronym>ISP</acronym>).</para>
@@ -409,11 +419,24 @@ host2.example.com link#1             UC 
       <screen>&prompt.root; <userinput>route add default 10.20.30.1</userinput></screen>
 
       <para>For more information on manual manipulation of network
-	routing tables, refer to &man.route.8;.</para>
+	routing tables, refer to &man.route.8;.</para>     
     </sect2>
 
-    <sect2 xml:id="network-dual-homed-hosts">
-      <title>Dual Homed Hosts</title>
+    <sect2 xml:id="network-static-routes">
+      <info>
+	<title>Configuring a Router with Static Routes</title>
+
+	<authorgroup>
+	  <author>
+	    <personname>
+	      <firstname>Al</firstname>
+	      <surname>Hoang</surname>
+	    </personname>
+	    <contrib>Contributed by </contrib>
+	  </author>
+	</authorgroup>
+      </info>
+      <!-- Feb 2004 -->
 
       <indexterm>
 	<primary>dual homed hosts</primary>
@@ -440,10 +463,6 @@ host2.example.com link#1             UC 
       <para>For this machine to forward packets between the two
 	interfaces, &os; must be configured as a router, as
 	demonstrated in the next section.</para>
-    </sect2>
-
-    <sect2 xml:id="network-dedicated-router">
-      <title>Building a Router</title>
 
       <indexterm>
 	<primary>router</primary>
@@ -482,26 +501,6 @@ host2.example.com link#1             UC 
 	sophisticated routing protocols is available with the
 	<package>net/zebra</package> package or
 	port.</para>
-    </sect2>
-
-    <sect2 xml:id="network-static-routes">
-      <info>
-	<title>Setting Up Static Routes</title>
-
-	<authorgroup>
-	  <author>
-	    <personname>
-	      <firstname>Al</firstname>
-	      <surname>Hoang</surname>
-	    </personname>
-	    <contrib>Contributed by </contrib>
-	  </author>
-	</authorgroup>
-      </info>
-      <!-- Feb 2004 -->
-
-      <sect3>
-	<title>Manual Configuration</title>
 
 	<para>Consider the following network:</para>
 
@@ -575,7 +574,6 @@ default            10.0.0.1           UG
 	  on the <systemitem
 	    class="ipaddress">192.168.2.0/24</systemitem>
 	  network.</para>
-      </sect3>
 
       <sect3>
 	<title>Persistent Configuration</title>


More information about the svn-doc-all mailing list