 Now, let's get another step ahead and let's understand when we talk about NGN, what exactly are the set of services and functionalities provided by the service stratum and the transport stratum and if there are other important modules in the overall NGN reference architecture. This figure is central to the overall understanding of NGN. If you look at it macroscopically, that is, if you look at the bird's eye view of it, you will see we have the applications which are connected through the application to network interface to the service stratum. Under the service stratum, we have the transport stratum. Under the service stratum and the transport stratum, we have certain functions. On the left hand side, we have the management functions including but not limited to the end user functions, the identity management or the identification management functions. We'll quickly run over these in this module and we'll go into respective detail once we are on a certain service stratum, transport stratum or any other modular description. Let's look at the service description at the service stratum in more detail. In the services stratum, we have the service control and content delivery, very importantly because when we talk about the service, the service has to be invoked, service has to be revoked, so it means service control has to be in place. What kind of content, what is the encoded format, what is the medium of it are all covered by the service control and content delivery. Then we also have the application and service support function. The application is our classical understanding in NGN that we have previously discussed, the services that we have seen, how these are supported by some additional or we can say VAS value added services functions. Then we have the transport stratum. The transport stratum is essentially related to number one, obviously the transport functions and the transport control functions. The transport control means to start transport, to end transport, to manage transport. The management aspect of the overall NGN reference model talks about what is not limited to the identity management which relates to the addressing, opening of a certain session, closing a certain session, the end user functionality. For instance, if a certain user is interested in knowing the log or the session related information of it, the overall how the performance is taking place, what have been the QoS benchmarks like NGN configuration and topology. It means how is the NGN initially configured? Is it configured for real time services or for non real time services? What is the underlying topology and is that topology best suited to the application that or the service that is being provided by the NGN? The control architecture that is the IMS IP multimedia subsystem architecture that provides control and call handling features to the NGN is another important management dimension. And of course, finally, there are a lot more details but we concluded for now that what is the kind of addressing scheme, the numbering naming like the IP addresses, the DNS, the telephone numbering used and as in SS7, how are all these integrated into the NGN is the scope of the management description as well. Let's look at this figure once more and we'll see that overall NGN architecture is so comprehensive that using appropriate interfaces, the NGN architecture is all tethered into a workable network. We'll go into all these details once we have the appropriate time.