-.. hidden-code-block:: xml
- :starthidden: True
- :label: See the XML platform description file...
-
- <?xml version='1.0'?>
- <!DOCTYPE platform SYSTEM "http://simgrid.gforge.inria.fr/simgrid/simgrid.dtd">
- <platform version="4.1">
- <zone id="AS0" routing="Full">
- <host id="host0" speed="1Gf"/>
- <host id="host1" speed="2Gf"/>
- <host id="host2" speed="40Gf"/>
- <link id="link0" bandwidth="125MBps" latency="100us"/>
- <link id="link1" bandwidth="50MBps" latency="150us"/>
- <link id="link2" bandwidth="250MBps" latency="50us"/>
- <route src="host0" dst="host1"><link_ctn id="link0"/><link_ctn id="link1"/></route>
- <route src="host1" dst="host2"><link_ctn id="link1"/><link_ctn id="link2"/></route>
- <route src="host0" dst="host2"><link_ctn id="link0"/><link_ctn id="link2"/></route>
- </zone>
- </platform>
-
-In this XML, note the way in which hosts, links, and routes are
-defined. All hosts are defined with a power (i.e., compute speed in
-Gflops), and links with a latency (in us) and bandwidth (in MBytes per
-second). Other units are possible and written as expected. By default,
-routes are symmetrical.
+.. literalinclude:: /tuto_smpi/3hosts.xml
+ :language: xml
+
+Note the way in which hosts, links, and routes are defined in
+this XML. All hosts are defined with a speed (in Gflops), and links
+with a latency (in us) and bandwidth (in MBytes per second). Other
+units are possible and written as expected. Routes specify the list of
+links encountered from one route to another. Routes are symmetrical by
+default.
+
+Cluster with a Crossbar
+^^^^^^^^^^^^^^^^^^^^^^^
+
+A very common parallel computing platform is a homogeneous cluster in
+which hosts are interconnected via a crossbar switch with as many
+ports as hosts, so that any disjoint pairs of hosts can communicate
+concurrently at full speed. For instance:
+
+Cluster with a Shared Backbone
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Another popular model for a parallel platform is that of a set of
+homogeneous hosts connected to a shared communication medium, a
+backbone, with some finite bandwidth capacity and on which
+communicating host pairs can experience contention. For instance:
