Any telecommunications technology that provides both a permanent, dedicated connection and the capability of quickly increasing bandwidth when needed by users.
Many telecommunications devices incorporate bandwidth-on-demand features of various types. For example, some Integrated Services Digital Network (ISDN) devices used for Basic Rate Interface ISDN (BRI-ISDN) can be configured to use the second ISDN B channel only when the utilization of the first channel exceeds a certain threshold. If this threshold is exceeded for a specified period of time, the second B channel automatically opens up to facilitate and speed data transfer.
Once the data rate has dropped below the threshold, the second B channel shuts down until it is needed again. The ISDN technology for accomplishing this combining of channels is called bonding. Many Asynchronous Transfer Mode (ATM) products also support various bandwidth-on-demand features.
Bandwidth-on-demand technologies are typically used in bursty networking situations in which high transmission speeds and capacities are required for transporting video, voice, and data on common networking circuits. Bandwidth-on-demand configurations often involve a mix of leased-line services and circuit-switched telecommunications services, and they can save users money by opening additional circuits only on an as-needed basis. Networks that make use of bandwidth on demand can be designed to supply additional bandwidth under conditions such as: