Added support for dual-homed hosts (on "classic" topo).

Change-Id: I47f4b3bf5756928452cbf99c4be2e3e1d6c8fa92
(cherry picked from commit 12c79edc912cce20596aa0cadc653ccd4d557cd8)
diff --git a/tools/test/topos/dual-onos.py b/tools/test/topos/dual-onos.py
new file mode 100644
index 0000000..b0b92ed
--- /dev/null
+++ b/tools/test/topos/dual-onos.py
@@ -0,0 +1,6 @@
+#!/usr/bin/python
+
+from onosnet import run
+from dual import DualTopo
+
+run( DualTopo() )
diff --git a/tools/test/topos/dual.json b/tools/test/topos/dual.json
new file mode 100644
index 0000000..fa86e0e
--- /dev/null
+++ b/tools/test/topos/dual.json
@@ -0,0 +1,21 @@
+{
+  "devices": {
+    "of:0000000000000001": { "basic": { "name": "SW-A" }},
+    "of:0000000000000002": { "basic": { "name": "SW-B" }}
+  },
+
+  "hosts": {
+    "00:00:00:00:00:01/-1": {
+      "basic": {
+        "locations": [
+          "of:0000000000000001/1",
+          "of:0000000000000002/1"
+        ],
+        "ips": [
+          "10.0.0.1"
+        ],
+        "name": "Host-X"
+      }
+    }
+  }
+}
diff --git a/tools/test/topos/dual.py b/tools/test/topos/dual.py
new file mode 100644
index 0000000..f0d7524
--- /dev/null
+++ b/tools/test/topos/dual.py
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+#!/usr/bin/env python
+
+"""
+"""
+from mininet.topo import Topo
+
+class DualTopo( Topo ):
+    """Switches and Dual-homed host"""
+
+    def __init__( self ):
+        """Create a topology."""
+
+        # Initialize Topology
+        Topo.__init__( self )
+
+        # add nodes, switches first...
+        LONDON = self.addSwitch( 's1' )
+        BRISTL = self.addSwitch( 's2' )
+
+        # ... and now hosts
+        LONDON_host = self.addHost( 'h1' )
+
+        # add edges between switch and corresponding host
+        self.addLink( LONDON, LONDON_host )
+        self.addLink( BRISTL, LONDON_host )
+
+        # add edges between switches
+        self.addLink( LONDON, BRISTL, bw=10, delay='1.0ms')
+
+
+topos = { 'dual': ( lambda: DualTopo() ) }
+
+if __name__ == '__main__':
+    from onosnet import run
+    run( DualTopo() )
diff --git a/tools/test/topos/dual.recipe b/tools/test/topos/dual.recipe
new file mode 100644
index 0000000..99dded7
--- /dev/null
+++ b/tools/test/topos/dual.recipe
@@ -0,0 +1,4 @@
+# Simple Dual topology recipe
+export OTD=2
+export OTL=1
+export OTH=1