Set-top box each module in the Internet high-speed access, work together. The user first requests a URL by sending a command. During a transaction using a PPP Point-to-Point protocol, the command eventually arrives on the modem common rack of the Internet business provider. The user then obtains the IP address used in this transaction and sends the request to the Internet through the dynamic allocation method. When the content of the Internet is found, it is then sent to the Internet business provider (ISP), and the ISP's router is responsible for sending it to the cable TV network and finally back to the user's set-top box. In cable TV set-top box, information content is intercepted. Set-top box completes a gateway task between TV and cable network. Its task is to manage the traffic of IP, with the ability to control the user in and out of the network once the IP packet arrives at the set-top box, separates the video signal from the packet, decodes the data, and then sends it to the browser for display on the TV.
Because cable modem requires users to configure a computer to access the Internet, affecting the user level of the expansion, and the use of set-top boxes do not need a computer, a TV machine is enough, so the market prospects of set-top boxes may be optimistic. Information users from the enterprise to the family transition, network bandwidth from narrowband to broadband transition, user network equipment from PC to set-top box (STB) TV transition, using the interface from Windows to the TV Remote Control key interface transition, information content from service for the enterprise to the People's Life services, is the general direction of network services development, set-top box (STB) is clearly a stage in this direction.