The Telnet is a protocol for the remote access from terminal in interactive modality allowing a user to connect to a remote host by becoming, precisely, virtual terminal, i.e. as if it were really local connected. The left figure shows the normal case where N.3 terminals are directly connected, through serial interface, to a host. The right figure shows the situation where the same performances are obtained through the Telnet protocol with host and PC in terminal emulation, set in remote points between them.