 We have been discussing the transport stratum after the service stratum and we have looked at different functional entities. Now we are going to get a little more into detail on various other aspects of the transport management. In this module we are going to look at the transport location management functional entity, the authentication and authorization functional entity and lastly the user profile entity. Let's recap what we have been seeing over the last couple of modules. Here you can see that within the transport stratum we have the transport location management, the transport authentication and authorization functional entity, the transport user profile functional entity. We are going to go into a little more detail on how these entities are used. The location management is one of the most important functions which is executed at the transport stratum. It is essentially the translation or mapping of the IP address onto the physical identifier of the customer premises equipment. It could also include mapping between the information which is provided by the network attachment and control functional entity which is given to the transport stratum in order to know which devices are connected in the transport plane. So the identifiers which are required for this particular location management are provided by the transport authentication and authorization functional entity. It means that the location management is carried out by the transport location management functional entity but the information which it requires could either come from network attachment control functional entity or by the authentication and authorization functional entity. There are broadly speaking two roles which are ascribed to this particular management. Number one it is the local management of the transport location management or the home location management. It could be possible that both the local and home location management are implemented in this case both would be applicable. Just to recall we can remember that when we were discussing network attachment and control functional entity we recalled mobile IP and we talked about the home agent and the foreign agent. So you can see that here also local is similar to what the home agent looks like and the home is what the home agent looks like and local is what the foreign agent looks like. Let's look at these in a little more detail. For a given user within a certain end terminal equipment the transport location management functional entity is responsible to look for the closest device from which it is going to extract the location information and it is going to bind it to the IP address. So this process involves discovering the nearest device and associating the identifier of that device with an IP address since this activity is local so it is given the name local. The home transport location management functional entity for the same user performs basically a macro referencing that is it maintains a pointer to the device which is currently the access or the attachment point for the user equipment. It means when the user equipment changes its own customer premises equipment or the gateway then correspondingly this home transport location management functional entity is going to update its pointer. Usually the scope of the home is usually a single domain. It means that as long as the user is within a single domain the home transport location management functional entity is going to maintain and update the current local of the user equipment for as long as the user is moving within a single administrative domain. But when a user moves outside of a specific domain then definitely it has to obtain a new temporary IP address. It means that now the home will have to look for and discover the local in the other domain. It is quite similar to how the mobile IP works as in home agent and the foreign agent. Now how this transport location management functional entity provides services to the querying entities. Number one the service control function which is there in the service stratum if it queries the transport location management functional entity and for example the proxy call service coordination or service control function in the IP multimedia subsystem. If it is looking for the let's say location of a certain device that is to which network device is the user equipment connected then the transport location management functional entity either as in local or home is going to respond to that. Then it is also useful to support mobility because within one NGN different administrative domains can be traversed. In that case the home or I would say the native service control function in the service stratum may contact the functional entity in the visited network to know where is what are the current whereabouts of the mobile device. Now the next important entity that we initially discussed that we are going to cover it is the transport authentication and authorization management functional entity. Now this is of course related to the allowing a device to enter into a network and utilize certain services so it means that there is a requirement to get some kind of user profile for that the transport user profile functional entity is queried and corresponding user data is retrieved. There is a consequence to that this authentication and authorization module or this functional entity can also be tasked to either permit a device have the access to the network or be denied for that IP address allocation role can be additionally assigned to it or it can suggest or it can alternately request the network attachment control functional entity to allocate an IP address to the customer equipment or the user equipment. This transport authentication and authorization functional entity can exist in the form of either a centralized server if the scope is limited of or it is if it is let's a large network in that case a proxy could be created of a centralized transport authentication and authorization functional entity and that proxy can work on behalf of the centralized server. Lastly the transport user profile functional entity is essentially a database that keeps record at the transport stratum related to user subscription. This subscription could be the authentication data which is required for subscribing a certain user to certain network or services or the transport subscription information. In the authentication data it could be the IDs of user the supported authentication mechanisms and in the transport subscription profile it could be the IP address or the IP prefix which are then used by different entities which query the user profile database.