diff --git a/custom/README b/custom/README
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+++ b/custom/README
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+This directory should hold configuration files for custom mininets.
+
+See custom_example.py, which loads the default minimal topology.  The advantage of defining a mininet in a separate file is that you then use the --custom option in mn to run the CLI or specific tests with it.
+
+To start up a mininet with the provided custom topology, do:
+  sudo mn --custom custom_example.py --topo mytopo
diff --git a/custom/carlos-topo.py b/custom/carlos-topo.py
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+"""Custom topology example
+
+Two directly connected switches plus a host for each switch:
+
+   host --- switch --- switch --- host
+
+Adding the 'topos' dict with a key/value pair to generate our newly defined
+topology enables one to pass in '--topo=mytopo' from the command line.
+"""
+
+from mininet.topo import Topo
+
+class MyTopo( Topo ):
+    "Simple topology example."
+
+    def __init__( self ):
+        "Create custom topo."
+
+        # Initialize topology
+        Topo.__init__( self )
+
+        # Add hosts and switches
+        client = self.addHost( 'h1' )
+	client.setIP('1.0.0.1')
+        router = self.addHost( 'h2' )
+	client.setIP('1.0.1.1',intf='h1-eth0')
+	client.setIP('2.0.1.2',intf='h1-eth1')
+	server = self.addHost( 'h3' )
+	client.setIP('2.0.0.1')
+
+        #leftSwitch = self.addSwitch( 's3' )
+        #rightSwitch = self.addSwitch( 's4' )
+
+        # Add links
+        #self.addLink( leftHost, leftSwitch )
+	#self.addLink( leftHost, rightSwitch)
+        #self.addLink( leftSwitch, rightSwitch )
+        #self.addLink( rightSwitch, rightHost )
+	self.addLink( client, router )
+	self.addLink( server, router )
+
+
+topos = { 'mytopo': ( lambda: MyTopo() ) }
diff --git a/custom/topo-2sw-2host.py b/custom/topo-2sw-2host.py
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+++ b/custom/topo-2sw-2host.py
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+"""Custom topology example
+
+Two directly connected switches plus a host for each switch:
+
+   host --- switch --- switch --- host
+
+Adding the 'topos' dict with a key/value pair to generate our newly defined
+topology enables one to pass in '--topo=mytopo' from the command line.
+"""
+
+from mininet.topo import Topo
+
+class MyTopo( Topo ):
+    "Simple topology example."
+
+    def __init__( self ):
+        "Create custom topo."
+
+        # Initialize topology
+        Topo.__init__( self )
+
+        # Add hosts and switches
+        leftHost = self.addHost( 'h1' )
+        rightHost = self.addHost( 'h2' )
+        leftSwitch = self.addSwitch( 's3' )
+        rightSwitch = self.addSwitch( 's4' )
+
+        # Add links
+        self.addLink( leftHost, leftSwitch )
+        self.addLink( leftSwitch, rightSwitch )
+        self.addLink( rightSwitch, rightHost )
+
+
+topos = { 'mytopo': ( lambda: MyTopo() ) }