fix Subnet bugs
diff --git a/plstackapi/core/models/subnet.py b/plstackapi/core/models/subnet.py
index 93a7ba5..8b1969a 100644
--- a/plstackapi/core/models/subnet.py
+++ b/plstackapi/core/models/subnet.py
@@ -29,7 +29,8 @@
                                           end = self.end)
             self.subnet_id = quantum_subnet['id']
             # add subnet as interface to slice's router
-            driver.add_router_interface(self.slice.router_id, self.subnet_id)
+            try: driver.add_router_interface(self.slice.router_id, self.subnet_id)
+            except: pass
             add_route = 'route add -net %s dev br-ex gw 10.100.0.5' % self.cidr
             commands.getstatusoutput(add_route)
 
@@ -38,8 +39,9 @@
     def delete(self, *args, **kwds):
         driver = OpenStackDriver()
         if self.subnet_id:
-            #driver.delete_router_interface(self.slice.router_id, self.subnet_id) 
+            try: driver.delete_router_interface(self.slice.router_id, self.subnet_id) 
+            except: pass
             driver.delete_subnet(self.subnet_id)
-        del_route = 'route del -net %s' % self.cidr 
+            del_route = 'route del -net %s' % self.cidr 
         commands.getstatusoutput(del_route)
         super(Subnet, self).delete(*args, **kwds)