There are many types of connection media for computer networks, which can be "wired" media such as cables, optical cables, twisted pairs, or "wireless" media such as satellite microwaves. This is the same as the transmission used in communication networks. The medium is basically the same.
On the basis of the connection medium, the computer network must realize the communication between computers and the sharing of computer resources. Therefore, its structure can be divided into two parts: communication subnet and resource subnet according to its functions. Of course, depending on the hardware, it is correct to divide it into two parts: the host and the communication subnet.