Add tunnel for more interesting example.

protogeni/test/sharedlink-v2.rspec

@@ -8,14 +8,25 @@ http://www.protogeni.net/resources/rspec/2/request.xsd"
         exclusive="false">
     <sliver_type name="emulab-openvz" />
     <interface client_id="left:if0" />
+    <interface client_id="left:tun0">
+      <ip address="192.168.44.5" netmask="255.255.255.0" type="ipv4"/>
+    </interface>
   </node>
   <node client_id="right"
         exclusive="false">
     <sliver_type name="emulab-openvz" />
     <interface client_id="right:if0" />
+    <interface client_id="right:tun0">
+      <ip address="192.168.44.3" netmask="255.255.255.0" type="ipv4"/>
+    </interface>
   </node>
   <link client_id="center">
     <interface_ref client_id="left:if0" />
     <interface_ref client_id="right:if0" />
   </link>
+  <link client_id="mytun">
+    <link_type name="gre-tunnel" />
+    <interface_ref client_id="left:tun0" />
+    <interface_ref client_id="right:tun0" />
+  </link>
 </rspec>