SEBA-89 Finish sync steps, add unit tests

Change-Id: I39495e6167fceffa4c86ad5e6c4d238271ecbcc7
diff --git a/xos/synchronizer/models/fabric-crossconnect.xproto b/xos/synchronizer/models/fabric-crossconnect.xproto
index 29b90e1..4a7e8dc 100644
--- a/xos/synchronizer/models/fabric-crossconnect.xproto
+++ b/xos/synchronizer/models/fabric-crossconnect.xproto
@@ -6,8 +6,12 @@
     option description="Fabric Crossconnect implementation";
 }
 
-
 message FabricCrossconnectServiceInstance (ServiceInstance){
     option verbose_name = "Fabric Crossconnect Service Instance";
     option owner_class_name="FabricCrossconnectService";
 }
+
+message BNGPortMapping (XOSBase) {
+    required int32 s_tag = 1 [help_text = "S Tag", null = False, db_index = False, blank = False, unique=True, tosca_key=True];
+    required int32 switch_port = 2 [help_text = "Port Number", null = False, db_index = False, blank = False];
+}