 The successful execution of an application or a service, for a certain user, is essentially related to the overall management of all the functions. It means NGN recognizes this particular reality and earmarks or allocates a specific module that implements all the management-related functionality. The management functions are primarily executed by the management function modules, but there is also a provision of integrating management in the service and transport stratum per se. But in this module, we are going to specifically look at how the management of resources and the overall execution of an application is done in the NGN. For that, we shall see how specifically quality, that we may call as quality of service, is overseen, how the security is managed and how the reliability is managed. The management functions are implemented in the NGN framework through proper functional entities, that is, we have management function performing entities. What these entities are? These could be simple network devices, these could be end servers or these could be agents which are installed on any network or host device. The management functionality is implemented in both the stratum, that is, the service stratum and the transport stratum. After all, management is such an important activity that it has to be performed at both these stratums. The scope of management is the entire network, that is, regarding the service provisioning, the application provisioning and whatever it takes. So specifically, the network management, the network element management, now what is the difference between the two? The network element management means the management of individual modules or the network element such as a host, a router, a bridge or a server. That's the network element. But once that network element management individually is concerned, it's called the network element management. But once the parts are integrated into a whole, then the network management issue comes up. So management functions essentially address both. Then there's also the service management, that is, how exactly is the service provisioned. Regarding the service provisioning, we have a metric, we all know it's called the quality of service. So the quality of service is defined in the form of some kind of contract or service level agreement. Then it is implemented in the form of how exactly the network is going to implement it. It's called the quality of network. The quality of network is how capable or how ready a certain network is to provide quality of service that was initially contracted between the end user and the NGN. And while a certain network achieves a part or whole of the quality of service is determined by the end user itself, that's called the quality of experience. Now these are the dimensions, of course not limited to these only, which come under the umbrella of the quality management. Then there's another aspect that the management functions implement, although the other modules in the transport and service stratum are also responsible for partly implementing the security. But security management as independent management functional modules are also deployed in the management functions. And why is that? Because the overall NGN is providing the open access to the services. Any user from any network can activate or request a certain application or a certain service. So it means there is some kind of openness to it. That's a concern because with this openness comes vulnerability as well. Then the internet by default is open. It means internet does not prevent anyone to access the NGN, be it a legitimate end user or it could even be a hacker. So it means the security mechanism has to be in place to check or to manage any kind of threat or vulnerability. Then we have the reliability management. Reliability is a very broad term because it can be understood with regards to the hardware infrastructure or it could be seen as how a certain application or a service is reliable or how long does it continue. It has so many aspects to it but for now we shall keep our scope limited by looking at certain aspects of reliability. The first one is of course the application or the service. How long is an application or service provided? Was it intermittent? Was it smooth? Was it on the schedule time? Was it delayed? Was it of certain quality? This all comes under the umbrella of reliability. Then if the service outage was observed, how quickly it was recovered? So all these come under the umbrella of the notion of the uptime, down time, repair time, availability etc. Now while designing the functional modules that implement reliability management of the overall NGN services, applications and the infrastructure, it is always a goal that is desired. It is an ideal goal that whatever is to be implemented, it has to be implemented on the benchmark or the gold standard of the public switch telephone networks and the well-known legacy systems which were providing individual services to their users. With NGN, since there is a lot of diversity and a lot of overlap in the kinds of services provided, so the complexity also correspondingly increases.