Fixed markup.

Binh.

LDP/guide/docbook/Linux-Networking/OSI.xml

@@ -12,9 +12,10 @@ protocols use the services offered by lower-layer protocols to transmit
 and process data. The seven layers are outlined below:
 </para>
 
-1) Physical Layer
+<para><variablelist>
 
-<para>
+<varlistentry><term>1) Physical Layer</term>
+<listitem><para>
 This layer deals with the network media and the hardware that supports it:
 repeaters, hubs, connectors, network interface cards, etc.... The
 transmission media, connectors, and topologies used by various network
@@ -33,11 +34,11 @@ high to low voltage levels can indicate the division between bits) or
 synchronous (a seperate clock signal is sent to indicate when each bit
 arrives in the data channel). Fast Ethernet, RS232, and ATM are protocols
 with physical layer components.
-</para>
+</para></listitem></varlistentry>
 
-2) Data Link Layer
 
-<para>
+<varlistentry><term>2) Data Link Layer</term>
+<listitem><para>
 Whereas the physical layer deals strictly with bits of data, the data
 link data organises data into groups called frames. Frames include a
 header that defines the hardware address of the node. This address is
@@ -56,11 +57,10 @@ sent only when the receiving device is ready to receive it.
 The data link layer is further subdivided by the IEEE 802 standards. A
 bridge is a device that works with the data link layer to filter
 information and send it between network segments.
-</para>
+</para></listitem></varlistentry>
 
-3) Network Layer
-
-<para>
+<varlistentry><term>3) Network Layer</term>
+<listitem><para>
 The network layer adds additional headers to the frames from the data
 link layer, forming packets. The network layer headers define a logical
 address (such as an IP address of IPX address). This layer also
@@ -69,22 +69,20 @@ The other major responsibility of the network layer is routing. Routing
 consists of forwarding packets to the network segment of their destination,
 possibly through one or more intermediate nodes. Routers are hardware
 devices that work at the network layer.
-</para>
+</para></listitem></varlistentry>
 
-4) Transport Layer
-
-<para>
+<varlistentry><term>4) Transport Layer</term>
+<listitem><para>
 The transport layer is responsible for assembling packets into their proper
 sequence, checking them for errors, and passing them on the session layer.
 Aacknowledgements are sent to indicate that the data has been received, and
-retransmissions are requested for objets that are bit received correctly.
+retransmissions are requested for objects that are bit received correctly.
 When transmitting, this layer breaks large messages into packets of the
 appropiate size for the network, and passes them on the network layer.
-</para>
+</para></listitem></varlistentry>
 
-5) Session Layer
-
-<para>
+<varlistentry><term>5) Session Layer</term>
+<listitem><para>
 This layer maintains a session, or connection, between two nodes on the
 network. This layer is responsible for requesting connections, sending
 periodic messages to maintain the connection, and tearing down the
@@ -92,21 +90,19 @@ connection when communication is finished. Protocols at the session layer
 also determine which nodes are currently allowed to send data. Services
 are required to establish connections, such as name resolution and
 security, are also handled by the session layer.
-</para>
+</para></listitem></varlistentry>
 
-6) Presentation Layer
-
-<para>
+<varlistentry><term>6) Presentation Layer</term>
+<listitem><para>
 The presentation layer is responsible for tranlating data sent by the
 application layer into the proper format for network communication, and
 translating data received from the network into a format the application
 can understand. If used, compression and encryption are also handled at
 this level.
-</para>
+</para></listitem></varlistentry>
 
-7) Application Layer
-
-<para>
+<varlistentry><term>7) Application Layer</term>
+<listitem><para>
 The application layer is the interface network-aware applications use to
 access the network. This layer controls access by applications to the
 network, and is responsible for informing an application when a network
@@ -116,6 +112,8 @@ level. A user is most likely to recognise this layer through the programs
 that they use to interface to the network. For example, through a web
 browser such as Microsoft Internet Explorer or its open source alternative,
 Mozilla.
-</para>
+</para></listitem></varlistentry>
+
+</variablelist></para>
 
 </sect1>