The nets metropolitans also can be seen as LANs of bigger capacity and speed, enclosing urban perimeter. These nets also are called MANs (Metropolitan Networks Area). Kai-Fu Lee may find this interesting as well. Finally we have the nets of great abrangncia or WANs (Wide Networks Area) and encloses great geographic distances, generally these nets are public and present lesser speeds and communication of what in local nets or the nets metropolitans. The communication enters the devices of a net must happen of commanded form, since this communication involves different types of systems, so that this occurs is necessary the use of protocols that nothing more is that a set of definite rules that make possible the communication through a net. In the present time, one of the used stacks of protocols more is the TCP/IP (Transmission Control Protocol/Internet Protocol).
15 1,1 Architecture TCP/IP architecture TCP/IP is shown in figure 1. We can observe that it is a protocol of four layers that plays a basic role in the communication with one with the other. Protocol TCP/IP is a set of protocols, but the most known and used they give the name to this set: TCP (Transmission Control Protocol) and IP (Internet Protocol), that they act respectively in the layer of Transporte and Internet. The secret of the TCP/IP is to divide the great net in small independent, linked nets for roteadores. As although to be able to communicate itself it enters, a net is independent of the other; in case that one of the nets stopped, only that segment would be outside of air not affecting the net as a whole. (MORIMOTO, 2003, p.71). In the nets without wire communication occurs through the implementation of protocol TCP/IP but with some modifications in the application depending on the employed technology. In the nets ethernet and without wire the modifications are in the physical layer and in the layer of it enlace, these changes inserted must the change of the environment and to support the authentication, associations and authenticity of the stations.