Fix ping pong desc generation error

Signed-off-by: Philip Joseph <philip.joseph@riftio.com>
diff --git a/examples/ping_pong_ns/rift/mano/examples/ping_pong_nsd.py b/examples/ping_pong_ns/rift/mano/examples/ping_pong_nsd.py
index d254cff..f047e5c 100755
--- a/examples/ping_pong_ns/rift/mano/examples/ping_pong_nsd.py
+++ b/examples/ping_pong_ns/rift/mano/examples/ping_pong_nsd.py
@@ -761,7 +761,7 @@
                 member.vnfd_id_ref = member_vnfd.descriptor.vnfd[0].id
                 member.member_vnf_index_ref = vnfd_index_map[member_vnfd]
 
-        # self.create_mon_params(vnfd_list)
+        self.create_mon_params(vnfd_list)
 
     def write_config(self, outdir, vnfds):
 
diff --git a/models/plugins/yang/nsd.yang b/models/plugins/yang/nsd.yang
index 1b62881..80b01a8 100644
--- a/models/plugins/yang/nsd.yang
+++ b/models/plugins/yang/nsd.yang
@@ -218,10 +218,12 @@
           }
         }
 
-        leaf-list member-vnf-index-ref {
+        leaf member-vnf-index-ref {
           description
             "Optional reference to member-vnf within constituent-vnfds";
-          type uint64;
+          type leafref {
+            path "../../../constituent-vnfd/member-vnf-index";
+          }
         }
       }
     }
diff --git a/models/plugins/yang/project-nsd.yang b/models/plugins/yang/project-nsd.yang
index e2be49d..1cf36af 100644
--- a/models/plugins/yang/project-nsd.yang
+++ b/models/plugins/yang/project-nsd.yang
@@ -357,10 +357,12 @@
           }
         }
 
-        leaf-list member-vnf-index-ref {
+        leaf member-vnf-index-ref {
           description
             "Optional reference to member-vnf within constituent-vnfds";
-          type uint64;
+          type leafref {
+            path "../../../constituent-vnfd/member-vnf-index";
+          }
         }
       }
     }
@@ -401,10 +403,12 @@
           }
         }
 
-        leaf-list member-vnf-index-ref {
+        leaf member-vnf-index-ref {
           description
             "Optional reference to member-vnf within constituent-vnfds";
-          type uint64;
+          type leafref {
+            path "../../../constituent-vnfd/member-vnf-index";
+          }
         }
       }
     }