 In the previous module, as I started, I said that the first and most important module in understanding the network and access control functions is to understand how the access management function is implemented. But then in the due course, I started off with network access and configuration functional entity. And there was a reason to that. The reason is that although to begin with, we see that network access configuration functional entity is what is related to the IP address because the IP address is the most important entity in the overall engine architecture. So IP address assignment was an important concern. But as you can see in this diagram that the access management functional entity is the first entity that interacts with the customer equipment. So it means that with the understanding of access management functional entity, we shall be able to know how exactly an equipment is connected to the network. After an equipment is connected to the network and it's an access is granted to it, then the IP address assignment takes place. So naturally IP address assignment is a mechanism that follows the access management, the access process. So we are going to look at what is the basic role of access management first and then what are the access mechanisms available. So the basic role of the access management is to make sure that the layer two connectivity is established. Now as you can see, we have just seen in the diagram that the location of the access management functional entity or the module is between the customer premises equipment and the network access configuration functional entity. So it is basically a layer two connection from the customer premises equipment to the network access and configuration functional and vice versa. It is more of a logical connection because different access technologies could be used. For instance, the point to point protocol, the Ethernet passive optical network, any layer two technology could be utilized. So it is more of a logical implementation. After having understood that a technology at layer two is implemented, then the next natural step is to ensure that an authorized customer premises equipment is allowed to access the network access and configuration. For that AAA is performed. The AAA is performed by using various technologies. The options are but not limited to the remote authentication dial-in user service. It's the radius which is quite old now. These days either diameter is used or any other proprietary standard is used. Even these technologies like 3G, PPP, 4G, LTE, they have their own layer two authentication authorization and accounting mechanisms. So depending on the overall access technology, its own AAA mechanisms can be initiated. So it means that the access management is done or is completed after the authentication is performed. And now the customer premises equipment or the user equipment is all set to get an IP address.