hannels of the same cable, broadband LAN technology can co-exist with currently existing services. Bandwidth The speed of a cable LAN is described by the bit rate of the modems used to send data over it. As this technology improves, cable LAN speeds may change, but at the time of this writing, cable modems range in speed from 500 Kbps to 10 Mbps, or roughly 17 to 340 times the bit rate of the familiar 28.8 Kbps telephone modem. This speed represents the peak rate at which a subscriber can send and receive data, during the periods of time when the medium is allocated to that subscriber. It does not imply that every subscriber can transfer data at that rate simultaneously. The effective average bandwidth seen by each subscriber depends on how busy the LAN is. Therefore, a cable LAN will appear to provide a variable bandwidth connection to the Internet Full-time connections Cable LAN bandwidth is allocated dynamically to a subscriber only when he has traffic to send. When he is not transferring traffic, he does not consume transmission resources. Consequently, he can always be connected to the Internet Point of Presence without requiring an expensive dedication of transmission resources. 4.2 Internet Access Via Telephone Company In contrast to the shared-bus architecture of a cable LAN, the telephone network requires the residential Internet provider to maintain multiple connection ports in order to serve multiple customers simultaneously. Thus, the residential Internet provider faces problems of multiplexing and concentration of individual subscriber lines very similar to those faced in telephone Central Offices. The point-to-point telephone network gives the residential Internet provider an architecture to work with that is fundamentally different from the cable plant. Instead of multiplexing the use of LAN transmission bandwidth as it is needed, subscribers multiplex the use of dedicated connections to the Internet provider over much lo...
