SEBA-108 acquire_service_instance and validate_links methods

Change-Id: Ie63de0fd7beb0aa50d4f482f7c1c9000ebb2cb34
diff --git a/xos/synchronizer/models/fabric-crossconnect.xproto b/xos/synchronizer/models/fabric-crossconnect.xproto
index d0d78e4..bbcfa66 100644
--- a/xos/synchronizer/models/fabric-crossconnect.xproto
+++ b/xos/synchronizer/models/fabric-crossconnect.xproto
@@ -11,9 +11,9 @@
     option verbose_name = "Fabric Crossconnect Service Instance";
     option owner_class_name="FabricCrossconnectService";
 
-    optional int32 s_tag = 1 [help_text = "s-tag"];
-    optional string switch_datapath_id = 2 [help_text = "switch datapath id"];
-    optional int32 source_port = 3 [help_text = "source port of fabric crossconnect"];
+    required int32 s_tag = 1 [help_text = "s-tag"];
+    required string switch_datapath_id = 2 [help_text = "switch datapath id"];
+    required int32 source_port = 3 [help_text = "source port of fabric crossconnect"];
 }
 
 message BNGPortMapping (XOSBase) {