Referencing - ACS responsibility

TR-069 based data models can become complex with referencing. Some examples of references are:

• internetGatewayDevice.Layer2Bridging.Filter.{i}.FilterInterface takes value of 'AvailableInterfaceKey' of table internetGatewayDevice.Layer2Briding.AvailableInterface.{i}
• internetGatewayDevice.Layer2Bridging.Marking.{i}.MarkingInterface takes value of 'AvailableInterfaceKey' of table internetGatewayDevice.Layer2Briding.AvailableInterface.{i}
• internetGatewayDevice.QueueManagement.Classification.{i}.ClassInterface takes one of the values from WANPPPConnection instances, WANIPConnection instances, Ethernet interface instances of LANDevices, USB interface instances of LANDevice, Wireless LAN interfaces instances of LANDevices or VLAN interface instances.
  

ACS implementation considerations:

• Must to have for interoperability:
  
• ACS must send referred instances first before sending referencing instances to the device. That is, if WANPPPConnection instance is referred by QueueManagement.Classification table, then WANPPPConnection instance creation and configuration must happen before Classification table instance is created and configured. Device may fail to accept the configuration if Classification instance is configured before configuring the referred WANPPPConnection. Hence, ACS must keep this ordering in mind while sending configuration to the devices.
• Note: Data model standard developers must never do the bidirectional cross referencing between two tables.
  
• ACS must not allow administrators to remove instances if they are being referred by others. Going by above example, ACS must not allow removal of WANPPPConnection instance if it is being referred by Classification instance. It should allow this operation only if WANPPPConnection instance reference is removed from the classification instance. Yet times, same instance is being referred from multiple places. Unless all the references are removed, it should not allow removal.
  
• Nice to have features
• ACS may display all possible places where a particular instance object is being referenced. For example, all references of WANPPPConnection instance can be displayed to the administrator so that he/she can remove references.